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linux/kernel/bpf/btf.c
Menglong Dong c317ab71fa bpf: Compute map_btf_id during build time 
For now, the field 'map_btf_id' in 'struct bpf_map_ops' for all map
types are computed during vmlinux-btf init:

  btf_parse_vmlinux() -> btf_vmlinux_map_ids_init()

It will lookup the btf_type according to the 'map_btf_name' field in
'struct bpf_map_ops'. This process can be done during build time,
thanks to Jiri's resolve_btfids.

selftest of map_ptr has passed:

  $96 map_ptr:OK
  Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-04-26 11:35:21 -07:00

7789 lines
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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2018 Facebook */
#include <uapi/linux/btf.h>
#include <uapi/linux/bpf.h>
#include <uapi/linux/bpf_perf_event.h>
#include <uapi/linux/types.h>
#include <linux/seq_file.h>
#include <linux/compiler.h>
#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/anon_inodes.h>
#include <linux/file.h>
#include <linux/uaccess.h>
#include <linux/kernel.h>
#include <linux/idr.h>
#include <linux/sort.h>
#include <linux/bpf_verifier.h>
#include <linux/btf.h>
#include <linux/btf_ids.h>
#include <linux/skmsg.h>
#include <linux/perf_event.h>
#include <linux/bsearch.h>
#include <linux/kobject.h>
#include <linux/sysfs.h>
#include <net/sock.h>
#include "../tools/lib/bpf/relo_core.h"
/* BTF (BPF Type Format) is the meta data format which describes
* the data types of BPF program/map. Hence, it basically focus
* on the C programming language which the modern BPF is primary
* using.
*
* ELF Section:
* ~~~~~~~~~~~
* The BTF data is stored under the ".BTF" ELF section
*
* struct btf_type:
* ~~~~~~~~~~~~~~~
* Each 'struct btf_type' object describes a C data type.
* Depending on the type it is describing, a 'struct btf_type'
* object may be followed by more data. F.e.
* To describe an array, 'struct btf_type' is followed by
* 'struct btf_array'.
*
* 'struct btf_type' and any extra data following it are
* 4 bytes aligned.
*
* Type section:
* ~~~~~~~~~~~~~
* The BTF type section contains a list of 'struct btf_type' objects.
* Each one describes a C type. Recall from the above section
* that a 'struct btf_type' object could be immediately followed by extra
* data in order to describe some particular C types.
*
* type_id:
* ~~~~~~~
* Each btf_type object is identified by a type_id. The type_id
* is implicitly implied by the location of the btf_type object in
* the BTF type section. The first one has type_id 1. The second
* one has type_id 2...etc. Hence, an earlier btf_type has
* a smaller type_id.
*
* A btf_type object may refer to another btf_type object by using
* type_id (i.e. the "type" in the "struct btf_type").
*
* NOTE that we cannot assume any reference-order.
* A btf_type object can refer to an earlier btf_type object
* but it can also refer to a later btf_type object.
*
* For example, to describe "const void *". A btf_type
* object describing "const" may refer to another btf_type
* object describing "void *". This type-reference is done
* by specifying type_id:
*
* [1] CONST (anon) type_id=2
* [2] PTR (anon) type_id=0
*
* The above is the btf_verifier debug log:
* - Each line started with "[?]" is a btf_type object
* - [?] is the type_id of the btf_type object.
* - CONST/PTR is the BTF_KIND_XXX
* - "(anon)" is the name of the type. It just
* happens that CONST and PTR has no name.
* - type_id=XXX is the 'u32 type' in btf_type
*
* NOTE: "void" has type_id 0
*
* String section:
* ~~~~~~~~~~~~~~
* The BTF string section contains the names used by the type section.
* Each string is referred by an "offset" from the beginning of the
* string section.
*
* Each string is '\0' terminated.
*
* The first character in the string section must be '\0'
* which is used to mean 'anonymous'. Some btf_type may not
* have a name.
*/
/* BTF verification:
*
* To verify BTF data, two passes are needed.
*
* Pass #1
* ~~~~~~~
* The first pass is to collect all btf_type objects to
* an array: "btf->types".
*
* Depending on the C type that a btf_type is describing,
* a btf_type may be followed by extra data. We don't know
* how many btf_type is there, and more importantly we don't
* know where each btf_type is located in the type section.
*
* Without knowing the location of each type_id, most verifications
* cannot be done. e.g. an earlier btf_type may refer to a later
* btf_type (recall the "const void *" above), so we cannot
* check this type-reference in the first pass.
*
* In the first pass, it still does some verifications (e.g.
* checking the name is a valid offset to the string section).
*
* Pass #2
* ~~~~~~~
* The main focus is to resolve a btf_type that is referring
* to another type.
*
* We have to ensure the referring type:
* 1) does exist in the BTF (i.e. in btf->types[])
* 2) does not cause a loop:
* struct A {
* struct B b;
* };
*
* struct B {
* struct A a;
* };
*
* btf_type_needs_resolve() decides if a btf_type needs
* to be resolved.
*
* The needs_resolve type implements the "resolve()" ops which
* essentially does a DFS and detects backedge.
*
* During resolve (or DFS), different C types have different
* "RESOLVED" conditions.
*
* When resolving a BTF_KIND_STRUCT, we need to resolve all its
* members because a member is always referring to another
* type. A struct's member can be treated as "RESOLVED" if
* it is referring to a BTF_KIND_PTR. Otherwise, the
* following valid C struct would be rejected:
*
* struct A {
* int m;
* struct A *a;
* };
*
* When resolving a BTF_KIND_PTR, it needs to keep resolving if
* it is referring to another BTF_KIND_PTR. Otherwise, we cannot
* detect a pointer loop, e.g.:
* BTF_KIND_CONST -> BTF_KIND_PTR -> BTF_KIND_CONST -> BTF_KIND_PTR +
* ^ |
* +-----------------------------------------+
*
*/
#define BITS_PER_U128 (sizeof(u64) * BITS_PER_BYTE * 2)
#define BITS_PER_BYTE_MASK (BITS_PER_BYTE - 1)
#define BITS_PER_BYTE_MASKED(bits) ((bits) & BITS_PER_BYTE_MASK)
#define BITS_ROUNDDOWN_BYTES(bits) ((bits) >> 3)
#define BITS_ROUNDUP_BYTES(bits) \
(BITS_ROUNDDOWN_BYTES(bits) + !!BITS_PER_BYTE_MASKED(bits))
#define BTF_INFO_MASK 0x9f00ffff
#define BTF_INT_MASK 0x0fffffff
#define BTF_TYPE_ID_VALID(type_id) ((type_id) <= BTF_MAX_TYPE)
#define BTF_STR_OFFSET_VALID(name_off) ((name_off) <= BTF_MAX_NAME_OFFSET)
/* 16MB for 64k structs and each has 16 members and
* a few MB spaces for the string section.
* The hard limit is S32_MAX.
*/
#define BTF_MAX_SIZE (16 * 1024 * 1024)
#define for_each_member_from(i, from, struct_type, member) \
for (i = from, member = btf_type_member(struct_type) + from; \
i < btf_type_vlen(struct_type); \
i++, member++)
#define for_each_vsi_from(i, from, struct_type, member) \
for (i = from, member = btf_type_var_secinfo(struct_type) + from; \
i < btf_type_vlen(struct_type); \
i++, member++)
DEFINE_IDR(btf_idr);
DEFINE_SPINLOCK(btf_idr_lock);
enum btf_kfunc_hook {
BTF_KFUNC_HOOK_XDP,
BTF_KFUNC_HOOK_TC,
BTF_KFUNC_HOOK_STRUCT_OPS,
BTF_KFUNC_HOOK_MAX,
};
enum {
BTF_KFUNC_SET_MAX_CNT = 32,
BTF_DTOR_KFUNC_MAX_CNT = 256,
};
struct btf_kfunc_set_tab {
struct btf_id_set *sets[BTF_KFUNC_HOOK_MAX][BTF_KFUNC_TYPE_MAX];
};
struct btf_id_dtor_kfunc_tab {
u32 cnt;
struct btf_id_dtor_kfunc dtors[];
};
struct btf {
void *data;
struct btf_type **types;
u32 *resolved_ids;
u32 *resolved_sizes;
const char *strings;
void *nohdr_data;
struct btf_header hdr;
u32 nr_types; /* includes VOID for base BTF */
u32 types_size;
u32 data_size;
refcount_t refcnt;
u32 id;
struct rcu_head rcu;
struct btf_kfunc_set_tab *kfunc_set_tab;
struct btf_id_dtor_kfunc_tab *dtor_kfunc_tab;
/* split BTF support */
struct btf *base_btf;
u32 start_id; /* first type ID in this BTF (0 for base BTF) */
u32 start_str_off; /* first string offset (0 for base BTF) */
char name[MODULE_NAME_LEN];
bool kernel_btf;
};
enum verifier_phase {
CHECK_META,
CHECK_TYPE,
};
struct resolve_vertex {
const struct btf_type *t;
u32 type_id;
u16 next_member;
};
enum visit_state {
NOT_VISITED,
VISITED,
RESOLVED,
};
enum resolve_mode {
RESOLVE_TBD, /* To Be Determined */
RESOLVE_PTR, /* Resolving for Pointer */
RESOLVE_STRUCT_OR_ARRAY, /* Resolving for struct/union
* or array
*/
};
#define MAX_RESOLVE_DEPTH 32
struct btf_sec_info {
u32 off;
u32 len;
};
struct btf_verifier_env {
struct btf *btf;
u8 *visit_states;
struct resolve_vertex stack[MAX_RESOLVE_DEPTH];
struct bpf_verifier_log log;
u32 log_type_id;
u32 top_stack;
enum verifier_phase phase;
enum resolve_mode resolve_mode;
};
static const char * const btf_kind_str[NR_BTF_KINDS] = {
[BTF_KIND_UNKN] = "UNKNOWN",
[BTF_KIND_INT] = "INT",
[BTF_KIND_PTR] = "PTR",
[BTF_KIND_ARRAY] = "ARRAY",
[BTF_KIND_STRUCT] = "STRUCT",
[BTF_KIND_UNION] = "UNION",
[BTF_KIND_ENUM] = "ENUM",
[BTF_KIND_FWD] = "FWD",
[BTF_KIND_TYPEDEF] = "TYPEDEF",
[BTF_KIND_VOLATILE] = "VOLATILE",
[BTF_KIND_CONST] = "CONST",
[BTF_KIND_RESTRICT] = "RESTRICT",
[BTF_KIND_FUNC] = "FUNC",
[BTF_KIND_FUNC_PROTO] = "FUNC_PROTO",
[BTF_KIND_VAR] = "VAR",
[BTF_KIND_DATASEC] = "DATASEC",
[BTF_KIND_FLOAT] = "FLOAT",
[BTF_KIND_DECL_TAG] = "DECL_TAG",
[BTF_KIND_TYPE_TAG] = "TYPE_TAG",
};
const char *btf_type_str(const struct btf_type *t)
{
return btf_kind_str[BTF_INFO_KIND(t->info)];
}
/* Chunk size we use in safe copy of data to be shown. */
#define BTF_SHOW_OBJ_SAFE_SIZE 32
/*
* This is the maximum size of a base type value (equivalent to a
* 128-bit int); if we are at the end of our safe buffer and have
* less than 16 bytes space we can't be assured of being able
* to copy the next type safely, so in such cases we will initiate
* a new copy.
*/
#define BTF_SHOW_OBJ_BASE_TYPE_SIZE 16
/* Type name size */
#define BTF_SHOW_NAME_SIZE 80
/*
* Common data to all BTF show operations. Private show functions can add
* their own data to a structure containing a struct btf_show and consult it
* in the show callback. See btf_type_show() below.
*
* One challenge with showing nested data is we want to skip 0-valued
* data, but in order to figure out whether a nested object is all zeros
* we need to walk through it. As a result, we need to make two passes
* when handling structs, unions and arrays; the first path simply looks
* for nonzero data, while the second actually does the display. The first
* pass is signalled by show->state.depth_check being set, and if we
* encounter a non-zero value we set show->state.depth_to_show to
* the depth at which we encountered it. When we have completed the
* first pass, we will know if anything needs to be displayed if
* depth_to_show > depth. See btf_[struct,array]_show() for the
* implementation of this.
*
* Another problem is we want to ensure the data for display is safe to
* access. To support this, the anonymous "struct {} obj" tracks the data
* object and our safe copy of it. We copy portions of the data needed
* to the object "copy" buffer, but because its size is limited to
* BTF_SHOW_OBJ_COPY_LEN bytes, multiple copies may be required as we
* traverse larger objects for display.
*
* The various data type show functions all start with a call to
* btf_show_start_type() which returns a pointer to the safe copy
* of the data needed (or if BTF_SHOW_UNSAFE is specified, to the
* raw data itself). btf_show_obj_safe() is responsible for
* using copy_from_kernel_nofault() to update the safe data if necessary
* as we traverse the object's data. skbuff-like semantics are
* used:
*
* - obj.head points to the start of the toplevel object for display
* - obj.size is the size of the toplevel object
* - obj.data points to the current point in the original data at
* which our safe data starts. obj.data will advance as we copy
* portions of the data.
*
* In most cases a single copy will suffice, but larger data structures
* such as "struct task_struct" will require many copies. The logic in
* btf_show_obj_safe() handles the logic that determines if a new
* copy_from_kernel_nofault() is needed.
*/
struct btf_show {
u64 flags;
void *target; /* target of show operation (seq file, buffer) */
void (*showfn)(struct btf_show *show, const char *fmt, va_list args);
const struct btf *btf;
/* below are used during iteration */
struct {
u8 depth;
u8 depth_to_show;
u8 depth_check;
u8 array_member:1,
array_terminated:1;
u16 array_encoding;
u32 type_id;
int status; /* non-zero for error */
const struct btf_type *type;
const struct btf_member *member;
char name[BTF_SHOW_NAME_SIZE]; /* space for member name/type */
} state;
struct {
u32 size;
void *head;
void *data;
u8 safe[BTF_SHOW_OBJ_SAFE_SIZE];
} obj;
};
struct btf_kind_operations {
s32 (*check_meta)(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left);
int (*resolve)(struct btf_verifier_env *env,
const struct resolve_vertex *v);
int (*check_member)(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type);
int (*check_kflag_member)(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type);
void (*log_details)(struct btf_verifier_env *env,
const struct btf_type *t);
void (*show)(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offsets,
struct btf_show *show);
};
static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS];
static struct btf_type btf_void;
static int btf_resolve(struct btf_verifier_env *env,
const struct btf_type *t, u32 type_id);
static int btf_func_check(struct btf_verifier_env *env,
const struct btf_type *t);
static bool btf_type_is_modifier(const struct btf_type *t)
{
/* Some of them is not strictly a C modifier
* but they are grouped into the same bucket
* for BTF concern:
* A type (t) that refers to another
* type through t->type AND its size cannot
* be determined without following the t->type.
*
* ptr does not fall into this bucket
* because its size is always sizeof(void *).
*/
switch (BTF_INFO_KIND(t->info)) {
case BTF_KIND_TYPEDEF:
case BTF_KIND_VOLATILE:
case BTF_KIND_CONST:
case BTF_KIND_RESTRICT:
case BTF_KIND_TYPE_TAG:
return true;
}
return false;
}
bool btf_type_is_void(const struct btf_type *t)
{
return t == &btf_void;
}
static bool btf_type_is_fwd(const struct btf_type *t)
{
return BTF_INFO_KIND(t->info) == BTF_KIND_FWD;
}
static bool btf_type_nosize(const struct btf_type *t)
{
return btf_type_is_void(t) || btf_type_is_fwd(t) ||
btf_type_is_func(t) || btf_type_is_func_proto(t);
}
static bool btf_type_nosize_or_null(const struct btf_type *t)
{
return !t || btf_type_nosize(t);
}
static bool __btf_type_is_struct(const struct btf_type *t)
{
return BTF_INFO_KIND(t->info) == BTF_KIND_STRUCT;
}
static bool btf_type_is_array(const struct btf_type *t)
{
return BTF_INFO_KIND(t->info) == BTF_KIND_ARRAY;
}
static bool btf_type_is_datasec(const struct btf_type *t)
{
return BTF_INFO_KIND(t->info) == BTF_KIND_DATASEC;
}
static bool btf_type_is_decl_tag(const struct btf_type *t)
{
return BTF_INFO_KIND(t->info) == BTF_KIND_DECL_TAG;
}
static bool btf_type_is_decl_tag_target(const struct btf_type *t)
{
return btf_type_is_func(t) || btf_type_is_struct(t) ||
btf_type_is_var(t) || btf_type_is_typedef(t);
}
u32 btf_nr_types(const struct btf *btf)
{
u32 total = 0;
while (btf) {
total += btf->nr_types;
btf = btf->base_btf;
}
return total;
}
s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind)
{
const struct btf_type *t;
const char *tname;
u32 i, total;
total = btf_nr_types(btf);
for (i = 1; i < total; i++) {
t = btf_type_by_id(btf, i);
if (BTF_INFO_KIND(t->info) != kind)
continue;
tname = btf_name_by_offset(btf, t->name_off);
if (!strcmp(tname, name))
return i;
}
return -ENOENT;
}
static s32 bpf_find_btf_id(const char *name, u32 kind, struct btf **btf_p)
{
struct btf *btf;
s32 ret;
int id;
btf = bpf_get_btf_vmlinux();
if (IS_ERR(btf))
return PTR_ERR(btf);
if (!btf)
return -EINVAL;
ret = btf_find_by_name_kind(btf, name, kind);
/* ret is never zero, since btf_find_by_name_kind returns
* positive btf_id or negative error.
*/
if (ret > 0) {
btf_get(btf);
*btf_p = btf;
return ret;
}
/* If name is not found in vmlinux's BTF then search in module's BTFs */
spin_lock_bh(&btf_idr_lock);
idr_for_each_entry(&btf_idr, btf, id) {
if (!btf_is_module(btf))
continue;
/* linear search could be slow hence unlock/lock
* the IDR to avoiding holding it for too long
*/
btf_get(btf);
spin_unlock_bh(&btf_idr_lock);
ret = btf_find_by_name_kind(btf, name, kind);
if (ret > 0) {
*btf_p = btf;
return ret;
}
spin_lock_bh(&btf_idr_lock);
btf_put(btf);
}
spin_unlock_bh(&btf_idr_lock);
return ret;
}
const struct btf_type *btf_type_skip_modifiers(const struct btf *btf,
u32 id, u32 *res_id)
{
const struct btf_type *t = btf_type_by_id(btf, id);
while (btf_type_is_modifier(t)) {
id = t->type;
t = btf_type_by_id(btf, t->type);
}
if (res_id)
*res_id = id;
return t;
}
const struct btf_type *btf_type_resolve_ptr(const struct btf *btf,
u32 id, u32 *res_id)
{
const struct btf_type *t;
t = btf_type_skip_modifiers(btf, id, NULL);
if (!btf_type_is_ptr(t))
return NULL;
return btf_type_skip_modifiers(btf, t->type, res_id);
}
const struct btf_type *btf_type_resolve_func_ptr(const struct btf *btf,
u32 id, u32 *res_id)
{
const struct btf_type *ptype;
ptype = btf_type_resolve_ptr(btf, id, res_id);
if (ptype && btf_type_is_func_proto(ptype))
return ptype;
return NULL;
}
/* Types that act only as a source, not sink or intermediate
* type when resolving.
*/
static bool btf_type_is_resolve_source_only(const struct btf_type *t)
{
return btf_type_is_var(t) ||
btf_type_is_decl_tag(t) ||
btf_type_is_datasec(t);
}
/* What types need to be resolved?
*
* btf_type_is_modifier() is an obvious one.
*
* btf_type_is_struct() because its member refers to
* another type (through member->type).
*
* btf_type_is_var() because the variable refers to
* another type. btf_type_is_datasec() holds multiple
* btf_type_is_var() types that need resolving.
*
* btf_type_is_array() because its element (array->type)
* refers to another type. Array can be thought of a
* special case of struct while array just has the same
* member-type repeated by array->nelems of times.
*/
static bool btf_type_needs_resolve(const struct btf_type *t)
{
return btf_type_is_modifier(t) ||
btf_type_is_ptr(t) ||
btf_type_is_struct(t) ||
btf_type_is_array(t) ||
btf_type_is_var(t) ||
btf_type_is_func(t) ||
btf_type_is_decl_tag(t) ||
btf_type_is_datasec(t);
}
/* t->size can be used */
static bool btf_type_has_size(const struct btf_type *t)
{
switch (BTF_INFO_KIND(t->info)) {
case BTF_KIND_INT:
case BTF_KIND_STRUCT:
case BTF_KIND_UNION:
case BTF_KIND_ENUM:
case BTF_KIND_DATASEC:
case BTF_KIND_FLOAT:
return true;
}
return false;
}
static const char *btf_int_encoding_str(u8 encoding)
{
if (encoding == 0)
return "(none)";
else if (encoding == BTF_INT_SIGNED)
return "SIGNED";
else if (encoding == BTF_INT_CHAR)
return "CHAR";
else if (encoding == BTF_INT_BOOL)
return "BOOL";
else
return "UNKN";
}
static u32 btf_type_int(const struct btf_type *t)
{
return *(u32 *)(t + 1);
}
static const struct btf_array *btf_type_array(const struct btf_type *t)
{
return (const struct btf_array *)(t + 1);
}
static const struct btf_enum *btf_type_enum(const struct btf_type *t)
{
return (const struct btf_enum *)(t + 1);
}
static const struct btf_var *btf_type_var(const struct btf_type *t)
{
return (const struct btf_var *)(t + 1);
}
static const struct btf_decl_tag *btf_type_decl_tag(const struct btf_type *t)
{
return (const struct btf_decl_tag *)(t + 1);
}
static const struct btf_kind_operations *btf_type_ops(const struct btf_type *t)
{
return kind_ops[BTF_INFO_KIND(t->info)];
}
static bool btf_name_offset_valid(const struct btf *btf, u32 offset)
{
if (!BTF_STR_OFFSET_VALID(offset))
return false;
while (offset < btf->start_str_off)
btf = btf->base_btf;
offset -= btf->start_str_off;
return offset < btf->hdr.str_len;
}
static bool __btf_name_char_ok(char c, bool first, bool dot_ok)
{
if ((first ? !isalpha(c) :
!isalnum(c)) &&
c != '_' &&
((c == '.' && !dot_ok) ||
c != '.'))
return false;
return true;
}
static const char *btf_str_by_offset(const struct btf *btf, u32 offset)
{
while (offset < btf->start_str_off)
btf = btf->base_btf;
offset -= btf->start_str_off;
if (offset < btf->hdr.str_len)
return &btf->strings[offset];
return NULL;
}
static bool __btf_name_valid(const struct btf *btf, u32 offset, bool dot_ok)
{
/* offset must be valid */
const char *src = btf_str_by_offset(btf, offset);
const char *src_limit;
if (!__btf_name_char_ok(*src, true, dot_ok))
return false;
/* set a limit on identifier length */
src_limit = src + KSYM_NAME_LEN;
src++;
while (*src && src < src_limit) {
if (!__btf_name_char_ok(*src, false, dot_ok))
return false;
src++;
}
return !*src;
}
/* Only C-style identifier is permitted. This can be relaxed if
* necessary.
*/
static bool btf_name_valid_identifier(const struct btf *btf, u32 offset)
{
return __btf_name_valid(btf, offset, false);
}
static bool btf_name_valid_section(const struct btf *btf, u32 offset)
{
return __btf_name_valid(btf, offset, true);
}
static const char *__btf_name_by_offset(const struct btf *btf, u32 offset)
{
const char *name;
if (!offset)
return "(anon)";
name = btf_str_by_offset(btf, offset);
return name ?: "(invalid-name-offset)";
}
const char *btf_name_by_offset(const struct btf *btf, u32 offset)
{
return btf_str_by_offset(btf, offset);
}
const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id)
{
while (type_id < btf->start_id)
btf = btf->base_btf;
type_id -= btf->start_id;
if (type_id >= btf->nr_types)
return NULL;
return btf->types[type_id];
}
/*
* Regular int is not a bit field and it must be either
* u8/u16/u32/u64 or __int128.
*/
static bool btf_type_int_is_regular(const struct btf_type *t)
{
u8 nr_bits, nr_bytes;
u32 int_data;
int_data = btf_type_int(t);
nr_bits = BTF_INT_BITS(int_data);
nr_bytes = BITS_ROUNDUP_BYTES(nr_bits);
if (BITS_PER_BYTE_MASKED(nr_bits) ||
BTF_INT_OFFSET(int_data) ||
(nr_bytes != sizeof(u8) && nr_bytes != sizeof(u16) &&
nr_bytes != sizeof(u32) && nr_bytes != sizeof(u64) &&
nr_bytes != (2 * sizeof(u64)))) {
return false;
}
return true;
}
/*
* Check that given struct member is a regular int with expected
* offset and size.
*/
bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
const struct btf_member *m,
u32 expected_offset, u32 expected_size)
{
const struct btf_type *t;
u32 id, int_data;
u8 nr_bits;
id = m->type;
t = btf_type_id_size(btf, &id, NULL);
if (!t || !btf_type_is_int(t))
return false;
int_data = btf_type_int(t);
nr_bits = BTF_INT_BITS(int_data);
if (btf_type_kflag(s)) {
u32 bitfield_size = BTF_MEMBER_BITFIELD_SIZE(m->offset);
u32 bit_offset = BTF_MEMBER_BIT_OFFSET(m->offset);
/* if kflag set, int should be a regular int and
* bit offset should be at byte boundary.
*/
return !bitfield_size &&
BITS_ROUNDUP_BYTES(bit_offset) == expected_offset &&
BITS_ROUNDUP_BYTES(nr_bits) == expected_size;
}
if (BTF_INT_OFFSET(int_data) ||
BITS_PER_BYTE_MASKED(m->offset) ||
BITS_ROUNDUP_BYTES(m->offset) != expected_offset ||
BITS_PER_BYTE_MASKED(nr_bits) ||
BITS_ROUNDUP_BYTES(nr_bits) != expected_size)
return false;
return true;
}
/* Similar to btf_type_skip_modifiers() but does not skip typedefs. */
static const struct btf_type *btf_type_skip_qualifiers(const struct btf *btf,
u32 id)
{
const struct btf_type *t = btf_type_by_id(btf, id);
while (btf_type_is_modifier(t) &&
BTF_INFO_KIND(t->info) != BTF_KIND_TYPEDEF) {
t = btf_type_by_id(btf, t->type);
}
return t;
}
#define BTF_SHOW_MAX_ITER 10
#define BTF_KIND_BIT(kind) (1ULL << kind)
/*
* Populate show->state.name with type name information.
* Format of type name is
*
* [.member_name = ] (type_name)
*/
static const char *btf_show_name(struct btf_show *show)
{
/* BTF_MAX_ITER array suffixes "[]" */
const char *array_suffixes = "[][][][][][][][][][]";
const char *array_suffix = &array_suffixes[strlen(array_suffixes)];
/* BTF_MAX_ITER pointer suffixes "*" */
const char *ptr_suffixes = "**********";
const char *ptr_suffix = &ptr_suffixes[strlen(ptr_suffixes)];
const char *name = NULL, *prefix = "", *parens = "";
const struct btf_member *m = show->state.member;
const struct btf_type *t;
const struct btf_array *array;
u32 id = show->state.type_id;
const char *member = NULL;
bool show_member = false;
u64 kinds = 0;
int i;
show->state.name[0] = '\0';
/*
* Don't show type name if we're showing an array member;
* in that case we show the array type so don't need to repeat
* ourselves for each member.
*/
if (show->state.array_member)
return "";
/* Retrieve member name, if any. */
if (m) {
member = btf_name_by_offset(show->btf, m->name_off);
show_member = strlen(member) > 0;
id = m->type;
}
/*
* Start with type_id, as we have resolved the struct btf_type *
* via btf_modifier_show() past the parent typedef to the child
* struct, int etc it is defined as. In such cases, the type_id
* still represents the starting type while the struct btf_type *
* in our show->state points at the resolved type of the typedef.
*/
t = btf_type_by_id(show->btf, id);
if (!t)
return "";
/*
* The goal here is to build up the right number of pointer and
* array suffixes while ensuring the type name for a typedef
* is represented. Along the way we accumulate a list of
* BTF kinds we have encountered, since these will inform later
* display; for example, pointer types will not require an
* opening "{" for struct, we will just display the pointer value.
*
* We also want to accumulate the right number of pointer or array
* indices in the format string while iterating until we get to
* the typedef/pointee/array member target type.
*
* We start by pointing at the end of pointer and array suffix
* strings; as we accumulate pointers and arrays we move the pointer
* or array string backwards so it will show the expected number of
* '*' or '[]' for the type. BTF_SHOW_MAX_ITER of nesting of pointers
* and/or arrays and typedefs are supported as a precaution.
*
* We also want to get typedef name while proceeding to resolve
* type it points to so that we can add parentheses if it is a
* "typedef struct" etc.
*/
for (i = 0; i < BTF_SHOW_MAX_ITER; i++) {
switch (BTF_INFO_KIND(t->info)) {
case BTF_KIND_TYPEDEF:
if (!name)
name = btf_name_by_offset(show->btf,
t->name_off);
kinds |= BTF_KIND_BIT(BTF_KIND_TYPEDEF);
id = t->type;
break;
case BTF_KIND_ARRAY:
kinds |= BTF_KIND_BIT(BTF_KIND_ARRAY);
parens = "[";
if (!t)
return "";
array = btf_type_array(t);
if (array_suffix > array_suffixes)
array_suffix -= 2;
id = array->type;
break;
case BTF_KIND_PTR:
kinds |= BTF_KIND_BIT(BTF_KIND_PTR);
if (ptr_suffix > ptr_suffixes)
ptr_suffix -= 1;
id = t->type;
break;
default:
id = 0;
break;
}
if (!id)
break;
t = btf_type_skip_qualifiers(show->btf, id);
}
/* We may not be able to represent this type; bail to be safe */
if (i == BTF_SHOW_MAX_ITER)
return "";
if (!name)
name = btf_name_by_offset(show->btf, t->name_off);
switch (BTF_INFO_KIND(t->info)) {
case BTF_KIND_STRUCT:
case BTF_KIND_UNION:
prefix = BTF_INFO_KIND(t->info) == BTF_KIND_STRUCT ?
"struct" : "union";
/* if it's an array of struct/union, parens is already set */
if (!(kinds & (BTF_KIND_BIT(BTF_KIND_ARRAY))))
parens = "{";
break;
case BTF_KIND_ENUM:
prefix = "enum";
break;
default:
break;
}
/* pointer does not require parens */
if (kinds & BTF_KIND_BIT(BTF_KIND_PTR))
parens = "";
/* typedef does not require struct/union/enum prefix */
if (kinds & BTF_KIND_BIT(BTF_KIND_TYPEDEF))
prefix = "";
if (!name)
name = "";
/* Even if we don't want type name info, we want parentheses etc */
if (show->flags & BTF_SHOW_NONAME)
snprintf(show->state.name, sizeof(show->state.name), "%s",
parens);
else
snprintf(show->state.name, sizeof(show->state.name),
"%s%s%s(%s%s%s%s%s%s)%s",
/* first 3 strings comprise ".member = " */
show_member ? "." : "",
show_member ? member : "",
show_member ? " = " : "",
/* ...next is our prefix (struct, enum, etc) */
prefix,
strlen(prefix) > 0 && strlen(name) > 0 ? " " : "",
/* ...this is the type name itself */
name,
/* ...suffixed by the appropriate '*', '[]' suffixes */
strlen(ptr_suffix) > 0 ? " " : "", ptr_suffix,
array_suffix, parens);
return show->state.name;
}
static const char *__btf_show_indent(struct btf_show *show)
{
const char *indents = " ";
const char *indent = &indents[strlen(indents)];
if ((indent - show->state.depth) >= indents)
return indent - show->state.depth;
return indents;
}
static const char *btf_show_indent(struct btf_show *show)
{
return show->flags & BTF_SHOW_COMPACT ? "" : __btf_show_indent(show);
}
static const char *btf_show_newline(struct btf_show *show)
{
return show->flags & BTF_SHOW_COMPACT ? "" : "\n";
}
static const char *btf_show_delim(struct btf_show *show)
{
if (show->state.depth == 0)
return "";
if ((show->flags & BTF_SHOW_COMPACT) && show->state.type &&
BTF_INFO_KIND(show->state.type->info) == BTF_KIND_UNION)
return "|";
return ",";
}
__printf(2, 3) static void btf_show(struct btf_show *show, const char *fmt, ...)
{
va_list args;
if (!show->state.depth_check) {
va_start(args, fmt);
show->showfn(show, fmt, args);
va_end(args);
}
}
/* Macros are used here as btf_show_type_value[s]() prepends and appends
* format specifiers to the format specifier passed in; these do the work of
* adding indentation, delimiters etc while the caller simply has to specify
* the type value(s) in the format specifier + value(s).
*/
#define btf_show_type_value(show, fmt, value) \
do { \
if ((value) != 0 || (show->flags & BTF_SHOW_ZERO) || \
show->state.depth == 0) { \
btf_show(show, "%s%s" fmt "%s%s", \
btf_show_indent(show), \
btf_show_name(show), \
value, btf_show_delim(show), \
btf_show_newline(show)); \
if (show->state.depth > show->state.depth_to_show) \
show->state.depth_to_show = show->state.depth; \
} \
} while (0)
#define btf_show_type_values(show, fmt, ...) \
do { \
btf_show(show, "%s%s" fmt "%s%s", btf_show_indent(show), \
btf_show_name(show), \
__VA_ARGS__, btf_show_delim(show), \
btf_show_newline(show)); \
if (show->state.depth > show->state.depth_to_show) \
show->state.depth_to_show = show->state.depth; \
} while (0)
/* How much is left to copy to safe buffer after @data? */
static int btf_show_obj_size_left(struct btf_show *show, void *data)
{
return show->obj.head + show->obj.size - data;
}
/* Is object pointed to by @data of @size already copied to our safe buffer? */
static bool btf_show_obj_is_safe(struct btf_show *show, void *data, int size)
{
return data >= show->obj.data &&
(data + size) < (show->obj.data + BTF_SHOW_OBJ_SAFE_SIZE);
}
/*
* If object pointed to by @data of @size falls within our safe buffer, return
* the equivalent pointer to the same safe data. Assumes
* copy_from_kernel_nofault() has already happened and our safe buffer is
* populated.
*/
static void *__btf_show_obj_safe(struct btf_show *show, void *data, int size)
{
if (btf_show_obj_is_safe(show, data, size))
return show->obj.safe + (data - show->obj.data);
return NULL;
}
/*
* Return a safe-to-access version of data pointed to by @data.
* We do this by copying the relevant amount of information
* to the struct btf_show obj.safe buffer using copy_from_kernel_nofault().
*
* If BTF_SHOW_UNSAFE is specified, just return data as-is; no
* safe copy is needed.
*
* Otherwise we need to determine if we have the required amount
* of data (determined by the @data pointer and the size of the
* largest base type we can encounter (represented by
* BTF_SHOW_OBJ_BASE_TYPE_SIZE). Having that much data ensures
* that we will be able to print some of the current object,
* and if more is needed a copy will be triggered.
* Some objects such as structs will not fit into the buffer;
* in such cases additional copies when we iterate over their
* members may be needed.
*
* btf_show_obj_safe() is used to return a safe buffer for
* btf_show_start_type(); this ensures that as we recurse into
* nested types we always have safe data for the given type.
* This approach is somewhat wasteful; it's possible for example
* that when iterating over a large union we'll end up copying the
* same data repeatedly, but the goal is safety not performance.
* We use stack data as opposed to per-CPU buffers because the
* iteration over a type can take some time, and preemption handling
* would greatly complicate use of the safe buffer.
*/
static void *btf_show_obj_safe(struct btf_show *show,
const struct btf_type *t,
void *data)
{
const struct btf_type *rt;
int size_left, size;
void *safe = NULL;
if (show->flags & BTF_SHOW_UNSAFE)
return data;
rt = btf_resolve_size(show->btf, t, &size);
if (IS_ERR(rt)) {
show->state.status = PTR_ERR(rt);
return NULL;
}
/*
* Is this toplevel object? If so, set total object size and
* initialize pointers. Otherwise check if we still fall within
* our safe object data.
*/
if (show->state.depth == 0) {
show->obj.size = size;
show->obj.head = data;
} else {
/*
* If the size of the current object is > our remaining
* safe buffer we _may_ need to do a new copy. However
* consider the case of a nested struct; it's size pushes
* us over the safe buffer limit, but showing any individual
* struct members does not. In such cases, we don't need
* to initiate a fresh copy yet; however we definitely need
* at least BTF_SHOW_OBJ_BASE_TYPE_SIZE bytes left
* in our buffer, regardless of the current object size.
* The logic here is that as we resolve types we will
* hit a base type at some point, and we need to be sure
* the next chunk of data is safely available to display
* that type info safely. We cannot rely on the size of
* the current object here because it may be much larger
* than our current buffer (e.g. task_struct is 8k).
* All we want to do here is ensure that we can print the
* next basic type, which we can if either
* - the current type size is within the safe buffer; or
* - at least BTF_SHOW_OBJ_BASE_TYPE_SIZE bytes are left in
* the safe buffer.
*/
safe = __btf_show_obj_safe(show, data,
min(size,
BTF_SHOW_OBJ_BASE_TYPE_SIZE));
}
/*
* We need a new copy to our safe object, either because we haven't
* yet copied and are initializing safe data, or because the data
* we want falls outside the boundaries of the safe object.
*/
if (!safe) {
size_left = btf_show_obj_size_left(show, data);
if (size_left > BTF_SHOW_OBJ_SAFE_SIZE)
size_left = BTF_SHOW_OBJ_SAFE_SIZE;
show->state.status = copy_from_kernel_nofault(show->obj.safe,
data, size_left);
if (!show->state.status) {
show->obj.data = data;
safe = show->obj.safe;
}
}
return safe;
}
/*
* Set the type we are starting to show and return a safe data pointer
* to be used for showing the associated data.
*/
static void *btf_show_start_type(struct btf_show *show,
const struct btf_type *t,
u32 type_id, void *data)
{
show->state.type = t;
show->state.type_id = type_id;
show->state.name[0] = '\0';
return btf_show_obj_safe(show, t, data);
}
static void btf_show_end_type(struct btf_show *show)
{
show->state.type = NULL;
show->state.type_id = 0;
show->state.name[0] = '\0';
}
static void *btf_show_start_aggr_type(struct btf_show *show,
const struct btf_type *t,
u32 type_id, void *data)
{
void *safe_data = btf_show_start_type(show, t, type_id, data);
if (!safe_data)
return safe_data;
btf_show(show, "%s%s%s", btf_show_indent(show),
btf_show_name(show),
btf_show_newline(show));
show->state.depth++;
return safe_data;
}
static void btf_show_end_aggr_type(struct btf_show *show,
const char *suffix)
{
show->state.depth--;
btf_show(show, "%s%s%s%s", btf_show_indent(show), suffix,
btf_show_delim(show), btf_show_newline(show));
btf_show_end_type(show);
}
static void btf_show_start_member(struct btf_show *show,
const struct btf_member *m)
{
show->state.member = m;
}
static void btf_show_start_array_member(struct btf_show *show)
{
show->state.array_member = 1;
btf_show_start_member(show, NULL);
}
static void btf_show_end_member(struct btf_show *show)
{
show->state.member = NULL;
}
static void btf_show_end_array_member(struct btf_show *show)
{
show->state.array_member = 0;
btf_show_end_member(show);
}
static void *btf_show_start_array_type(struct btf_show *show,
const struct btf_type *t,
u32 type_id,
u16 array_encoding,
void *data)
{
show->state.array_encoding = array_encoding;
show->state.array_terminated = 0;
return btf_show_start_aggr_type(show, t, type_id, data);
}
static void btf_show_end_array_type(struct btf_show *show)
{
show->state.array_encoding = 0;
show->state.array_terminated = 0;
btf_show_end_aggr_type(show, "]");
}
static void *btf_show_start_struct_type(struct btf_show *show,
const struct btf_type *t,
u32 type_id,
void *data)
{
return btf_show_start_aggr_type(show, t, type_id, data);
}
static void btf_show_end_struct_type(struct btf_show *show)
{
btf_show_end_aggr_type(show, "}");
}
__printf(2, 3) static void __btf_verifier_log(struct bpf_verifier_log *log,
const char *fmt, ...)
{
va_list args;
va_start(args, fmt);
bpf_verifier_vlog(log, fmt, args);
va_end(args);
}
__printf(2, 3) static void btf_verifier_log(struct btf_verifier_env *env,
const char *fmt, ...)
{
struct bpf_verifier_log *log = &env->log;
va_list args;
if (!bpf_verifier_log_needed(log))
return;
va_start(args, fmt);
bpf_verifier_vlog(log, fmt, args);
va_end(args);
}
__printf(4, 5) static void __btf_verifier_log_type(struct btf_verifier_env *env,
const struct btf_type *t,
bool log_details,
const char *fmt, ...)
{
struct bpf_verifier_log *log = &env->log;
u8 kind = BTF_INFO_KIND(t->info);
struct btf *btf = env->btf;
va_list args;
if (!bpf_verifier_log_needed(log))
return;
/* btf verifier prints all types it is processing via
* btf_verifier_log_type(..., fmt = NULL).
* Skip those prints for in-kernel BTF verification.
*/
if (log->level == BPF_LOG_KERNEL && !fmt)
return;
__btf_verifier_log(log, "[%u] %s %s%s",
env->log_type_id,
btf_kind_str[kind],
__btf_name_by_offset(btf, t->name_off),
log_details ? " " : "");
if (log_details)
btf_type_ops(t)->log_details(env, t);
if (fmt && *fmt) {
__btf_verifier_log(log, " ");
va_start(args, fmt);
bpf_verifier_vlog(log, fmt, args);
va_end(args);
}
__btf_verifier_log(log, "\n");
}
#define btf_verifier_log_type(env, t, ...) \
__btf_verifier_log_type((env), (t), true, __VA_ARGS__)
#define btf_verifier_log_basic(env, t, ...) \
__btf_verifier_log_type((env), (t), false, __VA_ARGS__)
__printf(4, 5)
static void btf_verifier_log_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const char *fmt, ...)
{
struct bpf_verifier_log *log = &env->log;
struct btf *btf = env->btf;
va_list args;
if (!bpf_verifier_log_needed(log))
return;
if (log->level == BPF_LOG_KERNEL && !fmt)
return;
/* The CHECK_META phase already did a btf dump.
*
* If member is logged again, it must hit an error in
* parsing this member. It is useful to print out which
* struct this member belongs to.
*/
if (env->phase != CHECK_META)
btf_verifier_log_type(env, struct_type, NULL);
if (btf_type_kflag(struct_type))
__btf_verifier_log(log,
"\t%s type_id=%u bitfield_size=%u bits_offset=%u",
__btf_name_by_offset(btf, member->name_off),
member->type,
BTF_MEMBER_BITFIELD_SIZE(member->offset),
BTF_MEMBER_BIT_OFFSET(member->offset));
else
__btf_verifier_log(log, "\t%s type_id=%u bits_offset=%u",
__btf_name_by_offset(btf, member->name_off),
member->type, member->offset);
if (fmt && *fmt) {
__btf_verifier_log(log, " ");
va_start(args, fmt);
bpf_verifier_vlog(log, fmt, args);
va_end(args);
}
__btf_verifier_log(log, "\n");
}
__printf(4, 5)
static void btf_verifier_log_vsi(struct btf_verifier_env *env,
const struct btf_type *datasec_type,
const struct btf_var_secinfo *vsi,
const char *fmt, ...)
{
struct bpf_verifier_log *log = &env->log;
va_list args;
if (!bpf_verifier_log_needed(log))
return;
if (log->level == BPF_LOG_KERNEL && !fmt)
return;
if (env->phase != CHECK_META)
btf_verifier_log_type(env, datasec_type, NULL);
__btf_verifier_log(log, "\t type_id=%u offset=%u size=%u",
vsi->type, vsi->offset, vsi->size);
if (fmt && *fmt) {
__btf_verifier_log(log, " ");
va_start(args, fmt);
bpf_verifier_vlog(log, fmt, args);
va_end(args);
}
__btf_verifier_log(log, "\n");
}
static void btf_verifier_log_hdr(struct btf_verifier_env *env,
u32 btf_data_size)
{
struct bpf_verifier_log *log = &env->log;
const struct btf *btf = env->btf;
const struct btf_header *hdr;
if (!bpf_verifier_log_needed(log))
return;
if (log->level == BPF_LOG_KERNEL)
return;
hdr = &btf->hdr;
__btf_verifier_log(log, "magic: 0x%x\n", hdr->magic);
__btf_verifier_log(log, "version: %u\n", hdr->version);
__btf_verifier_log(log, "flags: 0x%x\n", hdr->flags);
__btf_verifier_log(log, "hdr_len: %u\n", hdr->hdr_len);
__btf_verifier_log(log, "type_off: %u\n", hdr->type_off);
__btf_verifier_log(log, "type_len: %u\n", hdr->type_len);
__btf_verifier_log(log, "str_off: %u\n", hdr->str_off);
__btf_verifier_log(log, "str_len: %u\n", hdr->str_len);
__btf_verifier_log(log, "btf_total_size: %u\n", btf_data_size);
}
static int btf_add_type(struct btf_verifier_env *env, struct btf_type *t)
{
struct btf *btf = env->btf;
if (btf->types_size == btf->nr_types) {
/* Expand 'types' array */
struct btf_type **new_types;
u32 expand_by, new_size;
if (btf->start_id + btf->types_size == BTF_MAX_TYPE) {
btf_verifier_log(env, "Exceeded max num of types");
return -E2BIG;
}
expand_by = max_t(u32, btf->types_size >> 2, 16);
new_size = min_t(u32, BTF_MAX_TYPE,
btf->types_size + expand_by);
new_types = kvcalloc(new_size, sizeof(*new_types),
GFP_KERNEL | __GFP_NOWARN);
if (!new_types)
return -ENOMEM;
if (btf->nr_types == 0) {
if (!btf->base_btf) {
/* lazily init VOID type */
new_types[0] = &btf_void;
btf->nr_types++;
}
} else {
memcpy(new_types, btf->types,
sizeof(*btf->types) * btf->nr_types);
}
kvfree(btf->types);
btf->types = new_types;
btf->types_size = new_size;
}
btf->types[btf->nr_types++] = t;
return 0;
}
static int btf_alloc_id(struct btf *btf)
{
int id;
idr_preload(GFP_KERNEL);
spin_lock_bh(&btf_idr_lock);
id = idr_alloc_cyclic(&btf_idr, btf, 1, INT_MAX, GFP_ATOMIC);
if (id > 0)
btf->id = id;
spin_unlock_bh(&btf_idr_lock);
idr_preload_end();
if (WARN_ON_ONCE(!id))
return -ENOSPC;
return id > 0 ? 0 : id;
}
static void btf_free_id(struct btf *btf)
{
unsigned long flags;
/*
* In map-in-map, calling map_delete_elem() on outer
* map will call bpf_map_put on the inner map.
* It will then eventually call btf_free_id()
* on the inner map. Some of the map_delete_elem()
* implementation may have irq disabled, so
* we need to use the _irqsave() version instead
* of the _bh() version.
*/
spin_lock_irqsave(&btf_idr_lock, flags);
idr_remove(&btf_idr, btf->id);
spin_unlock_irqrestore(&btf_idr_lock, flags);
}
static void btf_free_kfunc_set_tab(struct btf *btf)
{
struct btf_kfunc_set_tab *tab = btf->kfunc_set_tab;
int hook, type;
if (!tab)
return;
/* For module BTF, we directly assign the sets being registered, so
* there is nothing to free except kfunc_set_tab.
*/
if (btf_is_module(btf))
goto free_tab;
for (hook = 0; hook < ARRAY_SIZE(tab->sets); hook++) {
for (type = 0; type < ARRAY_SIZE(tab->sets[0]); type++)
kfree(tab->sets[hook][type]);
}
free_tab:
kfree(tab);
btf->kfunc_set_tab = NULL;
}
static void btf_free_dtor_kfunc_tab(struct btf *btf)
{
struct btf_id_dtor_kfunc_tab *tab = btf->dtor_kfunc_tab;
if (!tab)
return;
kfree(tab);
btf->dtor_kfunc_tab = NULL;
}
static void btf_free(struct btf *btf)
{
btf_free_dtor_kfunc_tab(btf);
btf_free_kfunc_set_tab(btf);
kvfree(btf->types);
kvfree(btf->resolved_sizes);
kvfree(btf->resolved_ids);
kvfree(btf->data);
kfree(btf);
}
static void btf_free_rcu(struct rcu_head *rcu)
{
struct btf *btf = container_of(rcu, struct btf, rcu);
btf_free(btf);
}
void btf_get(struct btf *btf)
{
refcount_inc(&btf->refcnt);
}
void btf_put(struct btf *btf)
{
if (btf && refcount_dec_and_test(&btf->refcnt)) {
btf_free_id(btf);
call_rcu(&btf->rcu, btf_free_rcu);
}
}
static int env_resolve_init(struct btf_verifier_env *env)
{
struct btf *btf = env->btf;
u32 nr_types = btf->nr_types;
u32 *resolved_sizes = NULL;
u32 *resolved_ids = NULL;
u8 *visit_states = NULL;
resolved_sizes = kvcalloc(nr_types, sizeof(*resolved_sizes),
GFP_KERNEL | __GFP_NOWARN);
if (!resolved_sizes)
goto nomem;
resolved_ids = kvcalloc(nr_types, sizeof(*resolved_ids),
GFP_KERNEL | __GFP_NOWARN);
if (!resolved_ids)
goto nomem;
visit_states = kvcalloc(nr_types, sizeof(*visit_states),
GFP_KERNEL | __GFP_NOWARN);
if (!visit_states)
goto nomem;
btf->resolved_sizes = resolved_sizes;
btf->resolved_ids = resolved_ids;
env->visit_states = visit_states;
return 0;
nomem:
kvfree(resolved_sizes);
kvfree(resolved_ids);
kvfree(visit_states);
return -ENOMEM;
}
static void btf_verifier_env_free(struct btf_verifier_env *env)
{
kvfree(env->visit_states);
kfree(env);
}
static bool env_type_is_resolve_sink(const struct btf_verifier_env *env,
const struct btf_type *next_type)
{
switch (env->resolve_mode) {
case RESOLVE_TBD:
/* int, enum or void is a sink */
return !btf_type_needs_resolve(next_type);
case RESOLVE_PTR:
/* int, enum, void, struct, array, func or func_proto is a sink
* for ptr
*/
return !btf_type_is_modifier(next_type) &&
!btf_type_is_ptr(next_type);
case RESOLVE_STRUCT_OR_ARRAY:
/* int, enum, void, ptr, func or func_proto is a sink
* for struct and array
*/
return !btf_type_is_modifier(next_type) &&
!btf_type_is_array(next_type) &&
!btf_type_is_struct(next_type);
default:
BUG();
}
}
static bool env_type_is_resolved(const struct btf_verifier_env *env,
u32 type_id)
{
/* base BTF types should be resolved by now */
if (type_id < env->btf->start_id)
return true;
return env->visit_states[type_id - env->btf->start_id] == RESOLVED;
}
static int env_stack_push(struct btf_verifier_env *env,
const struct btf_type *t, u32 type_id)
{
const struct btf *btf = env->btf;
struct resolve_vertex *v;
if (env->top_stack == MAX_RESOLVE_DEPTH)
return -E2BIG;
if (type_id < btf->start_id
|| env->visit_states[type_id - btf->start_id] != NOT_VISITED)
return -EEXIST;
env->visit_states[type_id - btf->start_id] = VISITED;
v = &env->stack[env->top_stack++];
v->t = t;
v->type_id = type_id;
v->next_member = 0;
if (env->resolve_mode == RESOLVE_TBD) {
if (btf_type_is_ptr(t))
env->resolve_mode = RESOLVE_PTR;
else if (btf_type_is_struct(t) || btf_type_is_array(t))
env->resolve_mode = RESOLVE_STRUCT_OR_ARRAY;
}
return 0;
}
static void env_stack_set_next_member(struct btf_verifier_env *env,
u16 next_member)
{
env->stack[env->top_stack - 1].next_member = next_member;
}
static void env_stack_pop_resolved(struct btf_verifier_env *env,
u32 resolved_type_id,
u32 resolved_size)
{
u32 type_id = env->stack[--(env->top_stack)].type_id;
struct btf *btf = env->btf;
type_id -= btf->start_id; /* adjust to local type id */
btf->resolved_sizes[type_id] = resolved_size;
btf->resolved_ids[type_id] = resolved_type_id;
env->visit_states[type_id] = RESOLVED;
}
static const struct resolve_vertex *env_stack_peak(struct btf_verifier_env *env)
{
return env->top_stack ? &env->stack[env->top_stack - 1] : NULL;
}
/* Resolve the size of a passed-in "type"
*
* type: is an array (e.g. u32 array[x][y])
* return type: type "u32[x][y]", i.e. BTF_KIND_ARRAY,
* *type_size: (x * y * sizeof(u32)). Hence, *type_size always
* corresponds to the return type.
* *elem_type: u32
* *elem_id: id of u32
* *total_nelems: (x * y). Hence, individual elem size is
* (*type_size / *total_nelems)
* *type_id: id of type if it's changed within the function, 0 if not
*
* type: is not an array (e.g. const struct X)
* return type: type "struct X"
* *type_size: sizeof(struct X)
* *elem_type: same as return type ("struct X")
* *elem_id: 0
* *total_nelems: 1
* *type_id: id of type if it's changed within the function, 0 if not
*/
static const struct btf_type *
__btf_resolve_size(const struct btf *btf, const struct btf_type *type,
u32 *type_size, const struct btf_type **elem_type,
u32 *elem_id, u32 *total_nelems, u32 *type_id)
{
const struct btf_type *array_type = NULL;
const struct btf_array *array = NULL;
u32 i, size, nelems = 1, id = 0;
for (i = 0; i < MAX_RESOLVE_DEPTH; i++) {
switch (BTF_INFO_KIND(type->info)) {
/* type->size can be used */
case BTF_KIND_INT:
case BTF_KIND_STRUCT:
case BTF_KIND_UNION:
case BTF_KIND_ENUM:
case BTF_KIND_FLOAT:
size = type->size;
goto resolved;
case BTF_KIND_PTR:
size = sizeof(void *);
goto resolved;
/* Modifiers */
case BTF_KIND_TYPEDEF:
case BTF_KIND_VOLATILE:
case BTF_KIND_CONST:
case BTF_KIND_RESTRICT:
case BTF_KIND_TYPE_TAG:
id = type->type;
type = btf_type_by_id(btf, type->type);
break;
case BTF_KIND_ARRAY:
if (!array_type)
array_type = type;
array = btf_type_array(type);
if (nelems && array->nelems > U32_MAX / nelems)
return ERR_PTR(-EINVAL);
nelems *= array->nelems;
type = btf_type_by_id(btf, array->type);
break;
/* type without size */
default:
return ERR_PTR(-EINVAL);
}
}
return ERR_PTR(-EINVAL);
resolved:
if (nelems && size > U32_MAX / nelems)
return ERR_PTR(-EINVAL);
*type_size = nelems * size;
if (total_nelems)
*total_nelems = nelems;
if (elem_type)
*elem_type = type;
if (elem_id)
*elem_id = array ? array->type : 0;
if (type_id && id)
*type_id = id;
return array_type ? : type;
}
const struct btf_type *
btf_resolve_size(const struct btf *btf, const struct btf_type *type,
u32 *type_size)
{
return __btf_resolve_size(btf, type, type_size, NULL, NULL, NULL, NULL);
}
static u32 btf_resolved_type_id(const struct btf *btf, u32 type_id)
{
while (type_id < btf->start_id)
btf = btf->base_btf;
return btf->resolved_ids[type_id - btf->start_id];
}
/* The input param "type_id" must point to a needs_resolve type */
static const struct btf_type *btf_type_id_resolve(const struct btf *btf,
u32 *type_id)
{
*type_id = btf_resolved_type_id(btf, *type_id);
return btf_type_by_id(btf, *type_id);
}
static u32 btf_resolved_type_size(const struct btf *btf, u32 type_id)
{
while (type_id < btf->start_id)
btf = btf->base_btf;
return btf->resolved_sizes[type_id - btf->start_id];
}
const struct btf_type *btf_type_id_size(const struct btf *btf,
u32 *type_id, u32 *ret_size)
{
const struct btf_type *size_type;
u32 size_type_id = *type_id;
u32 size = 0;
size_type = btf_type_by_id(btf, size_type_id);
if (btf_type_nosize_or_null(size_type))
return NULL;
if (btf_type_has_size(size_type)) {
size = size_type->size;
} else if (btf_type_is_array(size_type)) {
size = btf_resolved_type_size(btf, size_type_id);
} else if (btf_type_is_ptr(size_type)) {
size = sizeof(void *);
} else {
if (WARN_ON_ONCE(!btf_type_is_modifier(size_type) &&
!btf_type_is_var(size_type)))
return NULL;
size_type_id = btf_resolved_type_id(btf, size_type_id);
size_type = btf_type_by_id(btf, size_type_id);
if (btf_type_nosize_or_null(size_type))
return NULL;
else if (btf_type_has_size(size_type))
size = size_type->size;
else if (btf_type_is_array(size_type))
size = btf_resolved_type_size(btf, size_type_id);
else if (btf_type_is_ptr(size_type))
size = sizeof(void *);
else
return NULL;
}
*type_id = size_type_id;
if (ret_size)
*ret_size = size;
return size_type;
}
static int btf_df_check_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
btf_verifier_log_basic(env, struct_type,
"Unsupported check_member");
return -EINVAL;
}
static int btf_df_check_kflag_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
btf_verifier_log_basic(env, struct_type,
"Unsupported check_kflag_member");
return -EINVAL;
}
/* Used for ptr, array struct/union and float type members.
* int, enum and modifier types have their specific callback functions.
*/
static int btf_generic_check_kflag_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
if (BTF_MEMBER_BITFIELD_SIZE(member->offset)) {
btf_verifier_log_member(env, struct_type, member,
"Invalid member bitfield_size");
return -EINVAL;
}
/* bitfield size is 0, so member->offset represents bit offset only.
* It is safe to call non kflag check_member variants.
*/
return btf_type_ops(member_type)->check_member(env, struct_type,
member,
member_type);
}
static int btf_df_resolve(struct btf_verifier_env *env,
const struct resolve_vertex *v)
{
btf_verifier_log_basic(env, v->t, "Unsupported resolve");
return -EINVAL;
}
static void btf_df_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offsets,
struct btf_show *show)
{
btf_show(show, "<unsupported kind:%u>", BTF_INFO_KIND(t->info));
}
static int btf_int_check_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
u32 int_data = btf_type_int(member_type);
u32 struct_bits_off = member->offset;
u32 struct_size = struct_type->size;
u32 nr_copy_bits;
u32 bytes_offset;
if (U32_MAX - struct_bits_off < BTF_INT_OFFSET(int_data)) {
btf_verifier_log_member(env, struct_type, member,
"bits_offset exceeds U32_MAX");
return -EINVAL;
}
struct_bits_off += BTF_INT_OFFSET(int_data);
bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
nr_copy_bits = BTF_INT_BITS(int_data) +
BITS_PER_BYTE_MASKED(struct_bits_off);
if (nr_copy_bits > BITS_PER_U128) {
btf_verifier_log_member(env, struct_type, member,
"nr_copy_bits exceeds 128");
return -EINVAL;
}
if (struct_size < bytes_offset ||
struct_size - bytes_offset < BITS_ROUNDUP_BYTES(nr_copy_bits)) {
btf_verifier_log_member(env, struct_type, member,
"Member exceeds struct_size");
return -EINVAL;
}
return 0;
}
static int btf_int_check_kflag_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
u32 struct_bits_off, nr_bits, nr_int_data_bits, bytes_offset;
u32 int_data = btf_type_int(member_type);
u32 struct_size = struct_type->size;
u32 nr_copy_bits;
/* a regular int type is required for the kflag int member */
if (!btf_type_int_is_regular(member_type)) {
btf_verifier_log_member(env, struct_type, member,
"Invalid member base type");
return -EINVAL;
}
/* check sanity of bitfield size */
nr_bits = BTF_MEMBER_BITFIELD_SIZE(member->offset);
struct_bits_off = BTF_MEMBER_BIT_OFFSET(member->offset);
nr_int_data_bits = BTF_INT_BITS(int_data);
if (!nr_bits) {
/* Not a bitfield member, member offset must be at byte
* boundary.
*/
if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
btf_verifier_log_member(env, struct_type, member,
"Invalid member offset");
return -EINVAL;
}
nr_bits = nr_int_data_bits;
} else if (nr_bits > nr_int_data_bits) {
btf_verifier_log_member(env, struct_type, member,
"Invalid member bitfield_size");
return -EINVAL;
}
bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
nr_copy_bits = nr_bits + BITS_PER_BYTE_MASKED(struct_bits_off);
if (nr_copy_bits > BITS_PER_U128) {
btf_verifier_log_member(env, struct_type, member,
"nr_copy_bits exceeds 128");
return -EINVAL;
}
if (struct_size < bytes_offset ||
struct_size - bytes_offset < BITS_ROUNDUP_BYTES(nr_copy_bits)) {
btf_verifier_log_member(env, struct_type, member,
"Member exceeds struct_size");
return -EINVAL;
}
return 0;
}
static s32 btf_int_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
u32 int_data, nr_bits, meta_needed = sizeof(int_data);
u16 encoding;
if (meta_left < meta_needed) {
btf_verifier_log_basic(env, t,
"meta_left:%u meta_needed:%u",
meta_left, meta_needed);
return -EINVAL;
}
if (btf_type_vlen(t)) {
btf_verifier_log_type(env, t, "vlen != 0");
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
int_data = btf_type_int(t);
if (int_data & ~BTF_INT_MASK) {
btf_verifier_log_basic(env, t, "Invalid int_data:%x",
int_data);
return -EINVAL;
}
nr_bits = BTF_INT_BITS(int_data) + BTF_INT_OFFSET(int_data);
if (nr_bits > BITS_PER_U128) {
btf_verifier_log_type(env, t, "nr_bits exceeds %zu",
BITS_PER_U128);
return -EINVAL;
}
if (BITS_ROUNDUP_BYTES(nr_bits) > t->size) {
btf_verifier_log_type(env, t, "nr_bits exceeds type_size");
return -EINVAL;
}
/*
* Only one of the encoding bits is allowed and it
* should be sufficient for the pretty print purpose (i.e. decoding).
* Multiple bits can be allowed later if it is found
* to be insufficient.
*/
encoding = BTF_INT_ENCODING(int_data);
if (encoding &&
encoding != BTF_INT_SIGNED &&
encoding != BTF_INT_CHAR &&
encoding != BTF_INT_BOOL) {
btf_verifier_log_type(env, t, "Unsupported encoding");
return -ENOTSUPP;
}
btf_verifier_log_type(env, t, NULL);
return meta_needed;
}
static void btf_int_log(struct btf_verifier_env *env,
const struct btf_type *t)
{
int int_data = btf_type_int(t);
btf_verifier_log(env,
"size=%u bits_offset=%u nr_bits=%u encoding=%s",
t->size, BTF_INT_OFFSET(int_data),
BTF_INT_BITS(int_data),
btf_int_encoding_str(BTF_INT_ENCODING(int_data)));
}
static void btf_int128_print(struct btf_show *show, void *data)
{
/* data points to a __int128 number.
* Suppose
* int128_num = *(__int128 *)data;
* The below formulas shows what upper_num and lower_num represents:
* upper_num = int128_num >> 64;
* lower_num = int128_num & 0xffffffffFFFFFFFFULL;
*/
u64 upper_num, lower_num;
#ifdef __BIG_ENDIAN_BITFIELD
upper_num = *(u64 *)data;
lower_num = *(u64 *)(data + 8);
#else
upper_num = *(u64 *)(data + 8);
lower_num = *(u64 *)data;
#endif
if (upper_num == 0)
btf_show_type_value(show, "0x%llx", lower_num);
else
btf_show_type_values(show, "0x%llx%016llx", upper_num,
lower_num);
}
static void btf_int128_shift(u64 *print_num, u16 left_shift_bits,
u16 right_shift_bits)
{
u64 upper_num, lower_num;
#ifdef __BIG_ENDIAN_BITFIELD
upper_num = print_num[0];
lower_num = print_num[1];
#else
upper_num = print_num[1];
lower_num = print_num[0];
#endif
/* shake out un-needed bits by shift/or operations */
if (left_shift_bits >= 64) {
upper_num = lower_num << (left_shift_bits - 64);
lower_num = 0;
} else {
upper_num = (upper_num << left_shift_bits) |
(lower_num >> (64 - left_shift_bits));
lower_num = lower_num << left_shift_bits;
}
if (right_shift_bits >= 64) {
lower_num = upper_num >> (right_shift_bits - 64);
upper_num = 0;
} else {
lower_num = (lower_num >> right_shift_bits) |
(upper_num << (64 - right_shift_bits));
upper_num = upper_num >> right_shift_bits;
}
#ifdef __BIG_ENDIAN_BITFIELD
print_num[0] = upper_num;
print_num[1] = lower_num;
#else
print_num[0] = lower_num;
print_num[1] = upper_num;
#endif
}
static void btf_bitfield_show(void *data, u8 bits_offset,
u8 nr_bits, struct btf_show *show)
{
u16 left_shift_bits, right_shift_bits;
u8 nr_copy_bytes;
u8 nr_copy_bits;
u64 print_num[2] = {};
nr_copy_bits = nr_bits + bits_offset;
nr_copy_bytes = BITS_ROUNDUP_BYTES(nr_copy_bits);
memcpy(print_num, data, nr_copy_bytes);
#ifdef __BIG_ENDIAN_BITFIELD
left_shift_bits = bits_offset;
#else
left_shift_bits = BITS_PER_U128 - nr_copy_bits;
#endif
right_shift_bits = BITS_PER_U128 - nr_bits;
btf_int128_shift(print_num, left_shift_bits, right_shift_bits);
btf_int128_print(show, print_num);
}
static void btf_int_bits_show(const struct btf *btf,
const struct btf_type *t,
void *data, u8 bits_offset,
struct btf_show *show)
{
u32 int_data = btf_type_int(t);
u8 nr_bits = BTF_INT_BITS(int_data);
u8 total_bits_offset;
/*
* bits_offset is at most 7.
* BTF_INT_OFFSET() cannot exceed 128 bits.
*/
total_bits_offset = bits_offset + BTF_INT_OFFSET(int_data);
data += BITS_ROUNDDOWN_BYTES(total_bits_offset);
bits_offset = BITS_PER_BYTE_MASKED(total_bits_offset);
btf_bitfield_show(data, bits_offset, nr_bits, show);
}
static void btf_int_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
{
u32 int_data = btf_type_int(t);
u8 encoding = BTF_INT_ENCODING(int_data);
bool sign = encoding & BTF_INT_SIGNED;
u8 nr_bits = BTF_INT_BITS(int_data);
void *safe_data;
safe_data = btf_show_start_type(show, t, type_id, data);
if (!safe_data)
return;
if (bits_offset || BTF_INT_OFFSET(int_data) ||
BITS_PER_BYTE_MASKED(nr_bits)) {
btf_int_bits_show(btf, t, safe_data, bits_offset, show);
goto out;
}
switch (nr_bits) {
case 128:
btf_int128_print(show, safe_data);
break;
case 64:
if (sign)
btf_show_type_value(show, "%lld", *(s64 *)safe_data);
else
btf_show_type_value(show, "%llu", *(u64 *)safe_data);
break;
case 32:
if (sign)
btf_show_type_value(show, "%d", *(s32 *)safe_data);
else
btf_show_type_value(show, "%u", *(u32 *)safe_data);
break;
case 16:
if (sign)
btf_show_type_value(show, "%d", *(s16 *)safe_data);
else
btf_show_type_value(show, "%u", *(u16 *)safe_data);
break;
case 8:
if (show->state.array_encoding == BTF_INT_CHAR) {
/* check for null terminator */
if (show->state.array_terminated)
break;
if (*(char *)data == '\0') {
show->state.array_terminated = 1;
break;
}
if (isprint(*(char *)data)) {
btf_show_type_value(show, "'%c'",
*(char *)safe_data);
break;
}
}
if (sign)
btf_show_type_value(show, "%d", *(s8 *)safe_data);
else
btf_show_type_value(show, "%u", *(u8 *)safe_data);
break;
default:
btf_int_bits_show(btf, t, safe_data, bits_offset, show);
break;
}
out:
btf_show_end_type(show);
}
static const struct btf_kind_operations int_ops = {
.check_meta = btf_int_check_meta,
.resolve = btf_df_resolve,
.check_member = btf_int_check_member,
.check_kflag_member = btf_int_check_kflag_member,
.log_details = btf_int_log,
.show = btf_int_show,
};
static int btf_modifier_check_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
const struct btf_type *resolved_type;
u32 resolved_type_id = member->type;
struct btf_member resolved_member;
struct btf *btf = env->btf;
resolved_type = btf_type_id_size(btf, &resolved_type_id, NULL);
if (!resolved_type) {
btf_verifier_log_member(env, struct_type, member,
"Invalid member");
return -EINVAL;
}
resolved_member = *member;
resolved_member.type = resolved_type_id;
return btf_type_ops(resolved_type)->check_member(env, struct_type,
&resolved_member,
resolved_type);
}
static int btf_modifier_check_kflag_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
const struct btf_type *resolved_type;
u32 resolved_type_id = member->type;
struct btf_member resolved_member;
struct btf *btf = env->btf;
resolved_type = btf_type_id_size(btf, &resolved_type_id, NULL);
if (!resolved_type) {
btf_verifier_log_member(env, struct_type, member,
"Invalid member");
return -EINVAL;
}
resolved_member = *member;
resolved_member.type = resolved_type_id;
return btf_type_ops(resolved_type)->check_kflag_member(env, struct_type,
&resolved_member,
resolved_type);
}
static int btf_ptr_check_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
u32 struct_size, struct_bits_off, bytes_offset;
struct_size = struct_type->size;
struct_bits_off = member->offset;
bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
btf_verifier_log_member(env, struct_type, member,
"Member is not byte aligned");
return -EINVAL;
}
if (struct_size - bytes_offset < sizeof(void *)) {
btf_verifier_log_member(env, struct_type, member,
"Member exceeds struct_size");
return -EINVAL;
}
return 0;
}
static int btf_ref_type_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
const char *value;
if (btf_type_vlen(t)) {
btf_verifier_log_type(env, t, "vlen != 0");
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
if (!BTF_TYPE_ID_VALID(t->type)) {
btf_verifier_log_type(env, t, "Invalid type_id");
return -EINVAL;
}
/* typedef/type_tag type must have a valid name, and other ref types,
* volatile, const, restrict, should have a null name.
*/
if (BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF) {
if (!t->name_off ||
!btf_name_valid_identifier(env->btf, t->name_off)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
} else if (BTF_INFO_KIND(t->info) == BTF_KIND_TYPE_TAG) {
value = btf_name_by_offset(env->btf, t->name_off);
if (!value || !value[0]) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
} else {
if (t->name_off) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
}
btf_verifier_log_type(env, t, NULL);
return 0;
}
static int btf_modifier_resolve(struct btf_verifier_env *env,
const struct resolve_vertex *v)
{
const struct btf_type *t = v->t;
const struct btf_type *next_type;
u32 next_type_id = t->type;
struct btf *btf = env->btf;
next_type = btf_type_by_id(btf, next_type_id);
if (!next_type || btf_type_is_resolve_source_only(next_type)) {
btf_verifier_log_type(env, v->t, "Invalid type_id");
return -EINVAL;
}
if (!env_type_is_resolve_sink(env, next_type) &&
!env_type_is_resolved(env, next_type_id))
return env_stack_push(env, next_type, next_type_id);
/* Figure out the resolved next_type_id with size.
* They will be stored in the current modifier's
* resolved_ids and resolved_sizes such that it can
* save us a few type-following when we use it later (e.g. in
* pretty print).
*/
if (!btf_type_id_size(btf, &next_type_id, NULL)) {
if (env_type_is_resolved(env, next_type_id))
next_type = btf_type_id_resolve(btf, &next_type_id);
/* "typedef void new_void", "const void"...etc */
if (!btf_type_is_void(next_type) &&
!btf_type_is_fwd(next_type) &&
!btf_type_is_func_proto(next_type)) {
btf_verifier_log_type(env, v->t, "Invalid type_id");
return -EINVAL;
}
}
env_stack_pop_resolved(env, next_type_id, 0);
return 0;
}
static int btf_var_resolve(struct btf_verifier_env *env,
const struct resolve_vertex *v)
{
const struct btf_type *next_type;
const struct btf_type *t = v->t;
u32 next_type_id = t->type;
struct btf *btf = env->btf;
next_type = btf_type_by_id(btf, next_type_id);
if (!next_type || btf_type_is_resolve_source_only(next_type)) {
btf_verifier_log_type(env, v->t, "Invalid type_id");
return -EINVAL;
}
if (!env_type_is_resolve_sink(env, next_type) &&
!env_type_is_resolved(env, next_type_id))
return env_stack_push(env, next_type, next_type_id);
if (btf_type_is_modifier(next_type)) {
const struct btf_type *resolved_type;
u32 resolved_type_id;
resolved_type_id = next_type_id;
resolved_type = btf_type_id_resolve(btf, &resolved_type_id);
if (btf_type_is_ptr(resolved_type) &&
!env_type_is_resolve_sink(env, resolved_type) &&
!env_type_is_resolved(env, resolved_type_id))
return env_stack_push(env, resolved_type,
resolved_type_id);
}
/* We must resolve to something concrete at this point, no
* forward types or similar that would resolve to size of
* zero is allowed.
*/
if (!btf_type_id_size(btf, &next_type_id, NULL)) {
btf_verifier_log_type(env, v->t, "Invalid type_id");
return -EINVAL;
}
env_stack_pop_resolved(env, next_type_id, 0);
return 0;
}
static int btf_ptr_resolve(struct btf_verifier_env *env,
const struct resolve_vertex *v)
{
const struct btf_type *next_type;
const struct btf_type *t = v->t;
u32 next_type_id = t->type;
struct btf *btf = env->btf;
next_type = btf_type_by_id(btf, next_type_id);
if (!next_type || btf_type_is_resolve_source_only(next_type)) {
btf_verifier_log_type(env, v->t, "Invalid type_id");
return -EINVAL;
}
if (!env_type_is_resolve_sink(env, next_type) &&
!env_type_is_resolved(env, next_type_id))
return env_stack_push(env, next_type, next_type_id);
/* If the modifier was RESOLVED during RESOLVE_STRUCT_OR_ARRAY,
* the modifier may have stopped resolving when it was resolved
* to a ptr (last-resolved-ptr).
*
* We now need to continue from the last-resolved-ptr to
* ensure the last-resolved-ptr will not referring back to
* the current ptr (t).
*/
if (btf_type_is_modifier(next_type)) {
const struct btf_type *resolved_type;
u32 resolved_type_id;
resolved_type_id = next_type_id;
resolved_type = btf_type_id_resolve(btf, &resolved_type_id);
if (btf_type_is_ptr(resolved_type) &&
!env_type_is_resolve_sink(env, resolved_type) &&
!env_type_is_resolved(env, resolved_type_id))
return env_stack_push(env, resolved_type,
resolved_type_id);
}
if (!btf_type_id_size(btf, &next_type_id, NULL)) {
if (env_type_is_resolved(env, next_type_id))
next_type = btf_type_id_resolve(btf, &next_type_id);
if (!btf_type_is_void(next_type) &&
!btf_type_is_fwd(next_type) &&
!btf_type_is_func_proto(next_type)) {
btf_verifier_log_type(env, v->t, "Invalid type_id");
return -EINVAL;
}
}
env_stack_pop_resolved(env, next_type_id, 0);
return 0;
}
static void btf_modifier_show(const struct btf *btf,
const struct btf_type *t,
u32 type_id, void *data,
u8 bits_offset, struct btf_show *show)
{
if (btf->resolved_ids)
t = btf_type_id_resolve(btf, &type_id);
else
t = btf_type_skip_modifiers(btf, type_id, NULL);
btf_type_ops(t)->show(btf, t, type_id, data, bits_offset, show);
}
static void btf_var_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
{
t = btf_type_id_resolve(btf, &type_id);
btf_type_ops(t)->show(btf, t, type_id, data, bits_offset, show);
}
static void btf_ptr_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
{
void *safe_data;
safe_data = btf_show_start_type(show, t, type_id, data);
if (!safe_data)
return;
/* It is a hashed value unless BTF_SHOW_PTR_RAW is specified */
if (show->flags & BTF_SHOW_PTR_RAW)
btf_show_type_value(show, "0x%px", *(void **)safe_data);
else
btf_show_type_value(show, "0x%p", *(void **)safe_data);
btf_show_end_type(show);
}
static void btf_ref_type_log(struct btf_verifier_env *env,
const struct btf_type *t)
{
btf_verifier_log(env, "type_id=%u", t->type);
}
static struct btf_kind_operations modifier_ops = {
.check_meta = btf_ref_type_check_meta,
.resolve = btf_modifier_resolve,
.check_member = btf_modifier_check_member,
.check_kflag_member = btf_modifier_check_kflag_member,
.log_details = btf_ref_type_log,
.show = btf_modifier_show,
};
static struct btf_kind_operations ptr_ops = {
.check_meta = btf_ref_type_check_meta,
.resolve = btf_ptr_resolve,
.check_member = btf_ptr_check_member,
.check_kflag_member = btf_generic_check_kflag_member,
.log_details = btf_ref_type_log,
.show = btf_ptr_show,
};
static s32 btf_fwd_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
if (btf_type_vlen(t)) {
btf_verifier_log_type(env, t, "vlen != 0");
return -EINVAL;
}
if (t->type) {
btf_verifier_log_type(env, t, "type != 0");
return -EINVAL;
}
/* fwd type must have a valid name */
if (!t->name_off ||
!btf_name_valid_identifier(env->btf, t->name_off)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
return 0;
}
static void btf_fwd_type_log(struct btf_verifier_env *env,
const struct btf_type *t)
{
btf_verifier_log(env, "%s", btf_type_kflag(t) ? "union" : "struct");
}
static struct btf_kind_operations fwd_ops = {
.check_meta = btf_fwd_check_meta,
.resolve = btf_df_resolve,
.check_member = btf_df_check_member,
.check_kflag_member = btf_df_check_kflag_member,
.log_details = btf_fwd_type_log,
.show = btf_df_show,
};
static int btf_array_check_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
u32 struct_bits_off = member->offset;
u32 struct_size, bytes_offset;
u32 array_type_id, array_size;
struct btf *btf = env->btf;
if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
btf_verifier_log_member(env, struct_type, member,
"Member is not byte aligned");
return -EINVAL;
}
array_type_id = member->type;
btf_type_id_size(btf, &array_type_id, &array_size);
struct_size = struct_type->size;
bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
if (struct_size - bytes_offset < array_size) {
btf_verifier_log_member(env, struct_type, member,
"Member exceeds struct_size");
return -EINVAL;
}
return 0;
}
static s32 btf_array_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
const struct btf_array *array = btf_type_array(t);
u32 meta_needed = sizeof(*array);
if (meta_left < meta_needed) {
btf_verifier_log_basic(env, t,
"meta_left:%u meta_needed:%u",
meta_left, meta_needed);
return -EINVAL;
}
/* array type should not have a name */
if (t->name_off) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
if (btf_type_vlen(t)) {
btf_verifier_log_type(env, t, "vlen != 0");
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
if (t->size) {
btf_verifier_log_type(env, t, "size != 0");
return -EINVAL;
}
/* Array elem type and index type cannot be in type void,
* so !array->type and !array->index_type are not allowed.
*/
if (!array->type || !BTF_TYPE_ID_VALID(array->type)) {
btf_verifier_log_type(env, t, "Invalid elem");
return -EINVAL;
}
if (!array->index_type || !BTF_TYPE_ID_VALID(array->index_type)) {
btf_verifier_log_type(env, t, "Invalid index");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
return meta_needed;
}
static int btf_array_resolve(struct btf_verifier_env *env,
const struct resolve_vertex *v)
{
const struct btf_array *array = btf_type_array(v->t);
const struct btf_type *elem_type, *index_type;
u32 elem_type_id, index_type_id;
struct btf *btf = env->btf;
u32 elem_size;
/* Check array->index_type */
index_type_id = array->index_type;
index_type = btf_type_by_id(btf, index_type_id);
if (btf_type_nosize_or_null(index_type) ||
btf_type_is_resolve_source_only(index_type)) {
btf_verifier_log_type(env, v->t, "Invalid index");
return -EINVAL;
}
if (!env_type_is_resolve_sink(env, index_type) &&
!env_type_is_resolved(env, index_type_id))
return env_stack_push(env, index_type, index_type_id);
index_type = btf_type_id_size(btf, &index_type_id, NULL);
if (!index_type || !btf_type_is_int(index_type) ||
!btf_type_int_is_regular(index_type)) {
btf_verifier_log_type(env, v->t, "Invalid index");
return -EINVAL;
}
/* Check array->type */
elem_type_id = array->type;
elem_type = btf_type_by_id(btf, elem_type_id);
if (btf_type_nosize_or_null(elem_type) ||
btf_type_is_resolve_source_only(elem_type)) {
btf_verifier_log_type(env, v->t,
"Invalid elem");
return -EINVAL;
}
if (!env_type_is_resolve_sink(env, elem_type) &&
!env_type_is_resolved(env, elem_type_id))
return env_stack_push(env, elem_type, elem_type_id);
elem_type = btf_type_id_size(btf, &elem_type_id, &elem_size);
if (!elem_type) {
btf_verifier_log_type(env, v->t, "Invalid elem");
return -EINVAL;
}
if (btf_type_is_int(elem_type) && !btf_type_int_is_regular(elem_type)) {
btf_verifier_log_type(env, v->t, "Invalid array of int");
return -EINVAL;
}
if (array->nelems && elem_size > U32_MAX / array->nelems) {
btf_verifier_log_type(env, v->t,
"Array size overflows U32_MAX");
return -EINVAL;
}
env_stack_pop_resolved(env, elem_type_id, elem_size * array->nelems);
return 0;
}
static void btf_array_log(struct btf_verifier_env *env,
const struct btf_type *t)
{
const struct btf_array *array = btf_type_array(t);
btf_verifier_log(env, "type_id=%u index_type_id=%u nr_elems=%u",
array->type, array->index_type, array->nelems);
}
static void __btf_array_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
{
const struct btf_array *array = btf_type_array(t);
const struct btf_kind_operations *elem_ops;
const struct btf_type *elem_type;
u32 i, elem_size = 0, elem_type_id;
u16 encoding = 0;
elem_type_id = array->type;
elem_type = btf_type_skip_modifiers(btf, elem_type_id, NULL);
if (elem_type && btf_type_has_size(elem_type))
elem_size = elem_type->size;
if (elem_type && btf_type_is_int(elem_type)) {
u32 int_type = btf_type_int(elem_type);
encoding = BTF_INT_ENCODING(int_type);
/*
* BTF_INT_CHAR encoding never seems to be set for
* char arrays, so if size is 1 and element is
* printable as a char, we'll do that.
*/
if (elem_size == 1)
encoding = BTF_INT_CHAR;
}
if (!btf_show_start_array_type(show, t, type_id, encoding, data))
return;
if (!elem_type)
goto out;
elem_ops = btf_type_ops(elem_type);
for (i = 0; i < array->nelems; i++) {
btf_show_start_array_member(show);
elem_ops->show(btf, elem_type, elem_type_id, data,
bits_offset, show);
data += elem_size;
btf_show_end_array_member(show);
if (show->state.array_terminated)
break;
}
out:
btf_show_end_array_type(show);
}
static void btf_array_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
{
const struct btf_member *m = show->state.member;
/*
* First check if any members would be shown (are non-zero).
* See comments above "struct btf_show" definition for more
* details on how this works at a high-level.
*/
if (show->state.depth > 0 && !(show->flags & BTF_SHOW_ZERO)) {
if (!show->state.depth_check) {
show->state.depth_check = show->state.depth + 1;
show->state.depth_to_show = 0;
}
__btf_array_show(btf, t, type_id, data, bits_offset, show);
show->state.member = m;
if (show->state.depth_check != show->state.depth + 1)
return;
show->state.depth_check = 0;
if (show->state.depth_to_show <= show->state.depth)
return;
/*
* Reaching here indicates we have recursed and found
* non-zero array member(s).
*/
}
__btf_array_show(btf, t, type_id, data, bits_offset, show);
}
static struct btf_kind_operations array_ops = {
.check_meta = btf_array_check_meta,
.resolve = btf_array_resolve,
.check_member = btf_array_check_member,
.check_kflag_member = btf_generic_check_kflag_member,
.log_details = btf_array_log,
.show = btf_array_show,
};
static int btf_struct_check_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
u32 struct_bits_off = member->offset;
u32 struct_size, bytes_offset;
if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
btf_verifier_log_member(env, struct_type, member,
"Member is not byte aligned");
return -EINVAL;
}
struct_size = struct_type->size;
bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
if (struct_size - bytes_offset < member_type->size) {
btf_verifier_log_member(env, struct_type, member,
"Member exceeds struct_size");
return -EINVAL;
}
return 0;
}
static s32 btf_struct_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
bool is_union = BTF_INFO_KIND(t->info) == BTF_KIND_UNION;
const struct btf_member *member;
u32 meta_needed, last_offset;
struct btf *btf = env->btf;
u32 struct_size = t->size;
u32 offset;
u16 i;
meta_needed = btf_type_vlen(t) * sizeof(*member);
if (meta_left < meta_needed) {
btf_verifier_log_basic(env, t,
"meta_left:%u meta_needed:%u",
meta_left, meta_needed);
return -EINVAL;
}
/* struct type either no name or a valid one */
if (t->name_off &&
!btf_name_valid_identifier(env->btf, t->name_off)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
last_offset = 0;
for_each_member(i, t, member) {
if (!btf_name_offset_valid(btf, member->name_off)) {
btf_verifier_log_member(env, t, member,
"Invalid member name_offset:%u",
member->name_off);
return -EINVAL;
}
/* struct member either no name or a valid one */
if (member->name_off &&
!btf_name_valid_identifier(btf, member->name_off)) {
btf_verifier_log_member(env, t, member, "Invalid name");
return -EINVAL;
}
/* A member cannot be in type void */
if (!member->type || !BTF_TYPE_ID_VALID(member->type)) {
btf_verifier_log_member(env, t, member,
"Invalid type_id");
return -EINVAL;
}
offset = __btf_member_bit_offset(t, member);
if (is_union && offset) {
btf_verifier_log_member(env, t, member,
"Invalid member bits_offset");
return -EINVAL;
}
/*
* ">" instead of ">=" because the last member could be
* "char a[0];"
*/
if (last_offset > offset) {
btf_verifier_log_member(env, t, member,
"Invalid member bits_offset");
return -EINVAL;
}
if (BITS_ROUNDUP_BYTES(offset) > struct_size) {
btf_verifier_log_member(env, t, member,
"Member bits_offset exceeds its struct size");
return -EINVAL;
}
btf_verifier_log_member(env, t, member, NULL);
last_offset = offset;
}
return meta_needed;
}
static int btf_struct_resolve(struct btf_verifier_env *env,
const struct resolve_vertex *v)
{
const struct btf_member *member;
int err;
u16 i;
/* Before continue resolving the next_member,
* ensure the last member is indeed resolved to a
* type with size info.
*/
if (v->next_member) {
const struct btf_type *last_member_type;
const struct btf_member *last_member;
u16 last_member_type_id;
last_member = btf_type_member(v->t) + v->next_member - 1;
last_member_type_id = last_member->type;
if (WARN_ON_ONCE(!env_type_is_resolved(env,
last_member_type_id)))
return -EINVAL;
last_member_type = btf_type_by_id(env->btf,
last_member_type_id);
if (btf_type_kflag(v->t))
err = btf_type_ops(last_member_type)->check_kflag_member(env, v->t,
last_member,
last_member_type);
else
err = btf_type_ops(last_member_type)->check_member(env, v->t,
last_member,
last_member_type);
if (err)
return err;
}
for_each_member_from(i, v->next_member, v->t, member) {
u32 member_type_id = member->type;
const struct btf_type *member_type = btf_type_by_id(env->btf,
member_type_id);
if (btf_type_nosize_or_null(member_type) ||
btf_type_is_resolve_source_only(member_type)) {
btf_verifier_log_member(env, v->t, member,
"Invalid member");
return -EINVAL;
}
if (!env_type_is_resolve_sink(env, member_type) &&
!env_type_is_resolved(env, member_type_id)) {
env_stack_set_next_member(env, i + 1);
return env_stack_push(env, member_type, member_type_id);
}
if (btf_type_kflag(v->t))
err = btf_type_ops(member_type)->check_kflag_member(env, v->t,
member,
member_type);
else
err = btf_type_ops(member_type)->check_member(env, v->t,
member,
member_type);
if (err)
return err;
}
env_stack_pop_resolved(env, 0, 0);
return 0;
}
static void btf_struct_log(struct btf_verifier_env *env,
const struct btf_type *t)
{
btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
}
enum btf_field_type {
BTF_FIELD_SPIN_LOCK,
BTF_FIELD_TIMER,
BTF_FIELD_KPTR,
};
enum {
BTF_FIELD_IGNORE = 0,
BTF_FIELD_FOUND = 1,
};
struct btf_field_info {
u32 type_id;
u32 off;
enum bpf_kptr_type type;
};
static int btf_find_struct(const struct btf *btf, const struct btf_type *t,
u32 off, int sz, struct btf_field_info *info)
{
if (!__btf_type_is_struct(t))
return BTF_FIELD_IGNORE;
if (t->size != sz)
return BTF_FIELD_IGNORE;
info->off = off;
return BTF_FIELD_FOUND;
}
static int btf_find_kptr(const struct btf *btf, const struct btf_type *t,
u32 off, int sz, struct btf_field_info *info)
{
enum bpf_kptr_type type;
u32 res_id;
/* For PTR, sz is always == 8 */
if (!btf_type_is_ptr(t))
return BTF_FIELD_IGNORE;
t = btf_type_by_id(btf, t->type);
if (!btf_type_is_type_tag(t))
return BTF_FIELD_IGNORE;
/* Reject extra tags */
if (btf_type_is_type_tag(btf_type_by_id(btf, t->type)))
return -EINVAL;
if (!strcmp("kptr", __btf_name_by_offset(btf, t->name_off)))
type = BPF_KPTR_UNREF;
else if (!strcmp("kptr_ref", __btf_name_by_offset(btf, t->name_off)))
type = BPF_KPTR_REF;
else
return -EINVAL;
/* Get the base type */
t = btf_type_skip_modifiers(btf, t->type, &res_id);
/* Only pointer to struct is allowed */
if (!__btf_type_is_struct(t))
return -EINVAL;
info->type_id = res_id;
info->off = off;
info->type = type;
return BTF_FIELD_FOUND;
}
static int btf_find_struct_field(const struct btf *btf, const struct btf_type *t,
const char *name, int sz, int align,
enum btf_field_type field_type,
struct btf_field_info *info, int info_cnt)
{
const struct btf_member *member;
struct btf_field_info tmp;
int ret, idx = 0;
u32 i, off;
for_each_member(i, t, member) {
const struct btf_type *member_type = btf_type_by_id(btf,
member->type);
if (name && strcmp(__btf_name_by_offset(btf, member_type->name_off), name))
continue;
off = __btf_member_bit_offset(t, member);
if (off % 8)
/* valid C code cannot generate such BTF */
return -EINVAL;
off /= 8;
if (off % align)
return -EINVAL;
switch (field_type) {
case BTF_FIELD_SPIN_LOCK:
case BTF_FIELD_TIMER:
ret = btf_find_struct(btf, member_type, off, sz,
idx < info_cnt ? &info[idx] : &tmp);
if (ret < 0)
return ret;
break;
case BTF_FIELD_KPTR:
ret = btf_find_kptr(btf, member_type, off, sz,
idx < info_cnt ? &info[idx] : &tmp);
if (ret < 0)
return ret;
break;
default:
return -EFAULT;
}
if (ret == BTF_FIELD_IGNORE)
continue;
if (idx >= info_cnt)
return -E2BIG;
++idx;
}
return idx;
}
static int btf_find_datasec_var(const struct btf *btf, const struct btf_type *t,
const char *name, int sz, int align,
enum btf_field_type field_type,
struct btf_field_info *info, int info_cnt)
{
const struct btf_var_secinfo *vsi;
struct btf_field_info tmp;
int ret, idx = 0;
u32 i, off;
for_each_vsi(i, t, vsi) {
const struct btf_type *var = btf_type_by_id(btf, vsi->type);
const struct btf_type *var_type = btf_type_by_id(btf, var->type);
off = vsi->offset;
if (name && strcmp(__btf_name_by_offset(btf, var_type->name_off), name))
continue;
if (vsi->size != sz)
continue;
if (off % align)
return -EINVAL;
switch (field_type) {
case BTF_FIELD_SPIN_LOCK:
case BTF_FIELD_TIMER:
ret = btf_find_struct(btf, var_type, off, sz,
idx < info_cnt ? &info[idx] : &tmp);
if (ret < 0)
return ret;
break;
case BTF_FIELD_KPTR:
ret = btf_find_kptr(btf, var_type, off, sz,
idx < info_cnt ? &info[idx] : &tmp);
if (ret < 0)
return ret;
break;
default:
return -EFAULT;
}
if (ret == BTF_FIELD_IGNORE)
continue;
if (idx >= info_cnt)
return -E2BIG;
++idx;
}
return idx;
}
static int btf_find_field(const struct btf *btf, const struct btf_type *t,
enum btf_field_type field_type,
struct btf_field_info *info, int info_cnt)
{
const char *name;
int sz, align;
switch (field_type) {
case BTF_FIELD_SPIN_LOCK:
name = "bpf_spin_lock";
sz = sizeof(struct bpf_spin_lock);
align = __alignof__(struct bpf_spin_lock);
break;
case BTF_FIELD_TIMER:
name = "bpf_timer";
sz = sizeof(struct bpf_timer);
align = __alignof__(struct bpf_timer);
break;
case BTF_FIELD_KPTR:
name = NULL;
sz = sizeof(u64);
align = 8;
break;
default:
return -EFAULT;
}
if (__btf_type_is_struct(t))
return btf_find_struct_field(btf, t, name, sz, align, field_type, info, info_cnt);
else if (btf_type_is_datasec(t))
return btf_find_datasec_var(btf, t, name, sz, align, field_type, info, info_cnt);
return -EINVAL;
}
/* find 'struct bpf_spin_lock' in map value.
* return >= 0 offset if found
* and < 0 in case of error
*/
int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t)
{
struct btf_field_info info;
int ret;
ret = btf_find_field(btf, t, BTF_FIELD_SPIN_LOCK, &info, 1);
if (ret < 0)
return ret;
if (!ret)
return -ENOENT;
return info.off;
}
int btf_find_timer(const struct btf *btf, const struct btf_type *t)
{
struct btf_field_info info;
int ret;
ret = btf_find_field(btf, t, BTF_FIELD_TIMER, &info, 1);
if (ret < 0)
return ret;
if (!ret)
return -ENOENT;
return info.off;
}
struct bpf_map_value_off *btf_parse_kptrs(const struct btf *btf,
const struct btf_type *t)
{
struct btf_field_info info_arr[BPF_MAP_VALUE_OFF_MAX];
struct bpf_map_value_off *tab;
struct btf *kernel_btf = NULL;
struct module *mod = NULL;
int ret, i, nr_off;
ret = btf_find_field(btf, t, BTF_FIELD_KPTR, info_arr, ARRAY_SIZE(info_arr));
if (ret < 0)
return ERR_PTR(ret);
if (!ret)
return NULL;
nr_off = ret;
tab = kzalloc(offsetof(struct bpf_map_value_off, off[nr_off]), GFP_KERNEL | __GFP_NOWARN);
if (!tab)
return ERR_PTR(-ENOMEM);
for (i = 0; i < nr_off; i++) {
const struct btf_type *t;
s32 id;
/* Find type in map BTF, and use it to look up the matching type
* in vmlinux or module BTFs, by name and kind.
*/
t = btf_type_by_id(btf, info_arr[i].type_id);
id = bpf_find_btf_id(__btf_name_by_offset(btf, t->name_off), BTF_INFO_KIND(t->info),
&kernel_btf);
if (id < 0) {
ret = id;
goto end;
}
/* Find and stash the function pointer for the destruction function that
* needs to be eventually invoked from the map free path.
*/
if (info_arr[i].type == BPF_KPTR_REF) {
const struct btf_type *dtor_func;
const char *dtor_func_name;
unsigned long addr;
s32 dtor_btf_id;
/* This call also serves as a whitelist of allowed objects that
* can be used as a referenced pointer and be stored in a map at
* the same time.
*/
dtor_btf_id = btf_find_dtor_kfunc(kernel_btf, id);
if (dtor_btf_id < 0) {
ret = dtor_btf_id;
goto end_btf;
}
dtor_func = btf_type_by_id(kernel_btf, dtor_btf_id);
if (!dtor_func) {
ret = -ENOENT;
goto end_btf;
}
if (btf_is_module(kernel_btf)) {
mod = btf_try_get_module(kernel_btf);
if (!mod) {
ret = -ENXIO;
goto end_btf;
}
}
/* We already verified dtor_func to be btf_type_is_func
* in register_btf_id_dtor_kfuncs.
*/
dtor_func_name = __btf_name_by_offset(kernel_btf, dtor_func->name_off);
addr = kallsyms_lookup_name(dtor_func_name);
if (!addr) {
ret = -EINVAL;
goto end_mod;
}
tab->off[i].kptr.dtor = (void *)addr;
}
tab->off[i].offset = info_arr[i].off;
tab->off[i].type = info_arr[i].type;
tab->off[i].kptr.btf_id = id;
tab->off[i].kptr.btf = kernel_btf;
tab->off[i].kptr.module = mod;
}
tab->nr_off = nr_off;
return tab;
end_mod:
module_put(mod);
end_btf:
btf_put(kernel_btf);
end:
while (i--) {
btf_put(tab->off[i].kptr.btf);
if (tab->off[i].kptr.module)
module_put(tab->off[i].kptr.module);
}
kfree(tab);
return ERR_PTR(ret);
}
static void __btf_struct_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
{
const struct btf_member *member;
void *safe_data;
u32 i;
safe_data = btf_show_start_struct_type(show, t, type_id, data);
if (!safe_data)
return;
for_each_member(i, t, member) {
const struct btf_type *member_type = btf_type_by_id(btf,
member->type);
const struct btf_kind_operations *ops;
u32 member_offset, bitfield_size;
u32 bytes_offset;
u8 bits8_offset;
btf_show_start_member(show, member);
member_offset = __btf_member_bit_offset(t, member);
bitfield_size = __btf_member_bitfield_size(t, member);
bytes_offset = BITS_ROUNDDOWN_BYTES(member_offset);
bits8_offset = BITS_PER_BYTE_MASKED(member_offset);
if (bitfield_size) {
safe_data = btf_show_start_type(show, member_type,
member->type,
data + bytes_offset);
if (safe_data)
btf_bitfield_show(safe_data,
bits8_offset,
bitfield_size, show);
btf_show_end_type(show);
} else {
ops = btf_type_ops(member_type);
ops->show(btf, member_type, member->type,
data + bytes_offset, bits8_offset, show);
}
btf_show_end_member(show);
}
btf_show_end_struct_type(show);
}
static void btf_struct_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
{
const struct btf_member *m = show->state.member;
/*
* First check if any members would be shown (are non-zero).
* See comments above "struct btf_show" definition for more
* details on how this works at a high-level.
*/
if (show->state.depth > 0 && !(show->flags & BTF_SHOW_ZERO)) {
if (!show->state.depth_check) {
show->state.depth_check = show->state.depth + 1;
show->state.depth_to_show = 0;
}
__btf_struct_show(btf, t, type_id, data, bits_offset, show);
/* Restore saved member data here */
show->state.member = m;
if (show->state.depth_check != show->state.depth + 1)
return;
show->state.depth_check = 0;
if (show->state.depth_to_show <= show->state.depth)
return;
/*
* Reaching here indicates we have recursed and found
* non-zero child values.
*/
}
__btf_struct_show(btf, t, type_id, data, bits_offset, show);
}
static struct btf_kind_operations struct_ops = {
.check_meta = btf_struct_check_meta,
.resolve = btf_struct_resolve,
.check_member = btf_struct_check_member,
.check_kflag_member = btf_generic_check_kflag_member,
.log_details = btf_struct_log,
.show = btf_struct_show,
};
static int btf_enum_check_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
u32 struct_bits_off = member->offset;
u32 struct_size, bytes_offset;
if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
btf_verifier_log_member(env, struct_type, member,
"Member is not byte aligned");
return -EINVAL;
}
struct_size = struct_type->size;
bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
if (struct_size - bytes_offset < member_type->size) {
btf_verifier_log_member(env, struct_type, member,
"Member exceeds struct_size");
return -EINVAL;
}
return 0;
}
static int btf_enum_check_kflag_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
u32 struct_bits_off, nr_bits, bytes_end, struct_size;
u32 int_bitsize = sizeof(int) * BITS_PER_BYTE;
struct_bits_off = BTF_MEMBER_BIT_OFFSET(member->offset);
nr_bits = BTF_MEMBER_BITFIELD_SIZE(member->offset);
if (!nr_bits) {
if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
btf_verifier_log_member(env, struct_type, member,
"Member is not byte aligned");
return -EINVAL;
}
nr_bits = int_bitsize;
} else if (nr_bits > int_bitsize) {
btf_verifier_log_member(env, struct_type, member,
"Invalid member bitfield_size");
return -EINVAL;
}
struct_size = struct_type->size;
bytes_end = BITS_ROUNDUP_BYTES(struct_bits_off + nr_bits);
if (struct_size < bytes_end) {
btf_verifier_log_member(env, struct_type, member,
"Member exceeds struct_size");
return -EINVAL;
}
return 0;
}
static s32 btf_enum_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
const struct btf_enum *enums = btf_type_enum(t);
struct btf *btf = env->btf;
u16 i, nr_enums;
u32 meta_needed;
nr_enums = btf_type_vlen(t);
meta_needed = nr_enums * sizeof(*enums);
if (meta_left < meta_needed) {
btf_verifier_log_basic(env, t,
"meta_left:%u meta_needed:%u",
meta_left, meta_needed);
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
if (t->size > 8 || !is_power_of_2(t->size)) {
btf_verifier_log_type(env, t, "Unexpected size");
return -EINVAL;
}
/* enum type either no name or a valid one */
if (t->name_off &&
!btf_name_valid_identifier(env->btf, t->name_off)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
for (i = 0; i < nr_enums; i++) {
if (!btf_name_offset_valid(btf, enums[i].name_off)) {
btf_verifier_log(env, "\tInvalid name_offset:%u",
enums[i].name_off);
return -EINVAL;
}
/* enum member must have a valid name */
if (!enums[i].name_off ||
!btf_name_valid_identifier(btf, enums[i].name_off)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
if (env->log.level == BPF_LOG_KERNEL)
continue;
btf_verifier_log(env, "\t%s val=%d\n",
__btf_name_by_offset(btf, enums[i].name_off),
enums[i].val);
}
return meta_needed;
}
static void btf_enum_log(struct btf_verifier_env *env,
const struct btf_type *t)
{
btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
}
static void btf_enum_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
{
const struct btf_enum *enums = btf_type_enum(t);
u32 i, nr_enums = btf_type_vlen(t);
void *safe_data;
int v;
safe_data = btf_show_start_type(show, t, type_id, data);
if (!safe_data)
return;
v = *(int *)safe_data;
for (i = 0; i < nr_enums; i++) {
if (v != enums[i].val)
continue;
btf_show_type_value(show, "%s",
__btf_name_by_offset(btf,
enums[i].name_off));
btf_show_end_type(show);
return;
}
btf_show_type_value(show, "%d", v);
btf_show_end_type(show);
}
static struct btf_kind_operations enum_ops = {
.check_meta = btf_enum_check_meta,
.resolve = btf_df_resolve,
.check_member = btf_enum_check_member,
.check_kflag_member = btf_enum_check_kflag_member,
.log_details = btf_enum_log,
.show = btf_enum_show,
};
static s32 btf_func_proto_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
u32 meta_needed = btf_type_vlen(t) * sizeof(struct btf_param);
if (meta_left < meta_needed) {
btf_verifier_log_basic(env, t,
"meta_left:%u meta_needed:%u",
meta_left, meta_needed);
return -EINVAL;
}
if (t->name_off) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
return meta_needed;
}
static void btf_func_proto_log(struct btf_verifier_env *env,
const struct btf_type *t)
{
const struct btf_param *args = (const struct btf_param *)(t + 1);
u16 nr_args = btf_type_vlen(t), i;
btf_verifier_log(env, "return=%u args=(", t->type);
if (!nr_args) {
btf_verifier_log(env, "void");
goto done;
}
if (nr_args == 1 && !args[0].type) {
/* Only one vararg */
btf_verifier_log(env, "vararg");
goto done;
}
btf_verifier_log(env, "%u %s", args[0].type,
__btf_name_by_offset(env->btf,
args[0].name_off));
for (i = 1; i < nr_args - 1; i++)
btf_verifier_log(env, ", %u %s", args[i].type,
__btf_name_by_offset(env->btf,
args[i].name_off));
if (nr_args > 1) {
const struct btf_param *last_arg = &args[nr_args - 1];
if (last_arg->type)
btf_verifier_log(env, ", %u %s", last_arg->type,
__btf_name_by_offset(env->btf,
last_arg->name_off));
else
btf_verifier_log(env, ", vararg");
}
done:
btf_verifier_log(env, ")");
}
static struct btf_kind_operations func_proto_ops = {
.check_meta = btf_func_proto_check_meta,
.resolve = btf_df_resolve,
/*
* BTF_KIND_FUNC_PROTO cannot be directly referred by
* a struct's member.
*
* It should be a function pointer instead.
* (i.e. struct's member -> BTF_KIND_PTR -> BTF_KIND_FUNC_PROTO)
*
* Hence, there is no btf_func_check_member().
*/
.check_member = btf_df_check_member,
.check_kflag_member = btf_df_check_kflag_member,
.log_details = btf_func_proto_log,
.show = btf_df_show,
};
static s32 btf_func_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
if (!t->name_off ||
!btf_name_valid_identifier(env->btf, t->name_off)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
if (btf_type_vlen(t) > BTF_FUNC_GLOBAL) {
btf_verifier_log_type(env, t, "Invalid func linkage");
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
return 0;
}
static int btf_func_resolve(struct btf_verifier_env *env,
const struct resolve_vertex *v)
{
const struct btf_type *t = v->t;
u32 next_type_id = t->type;
int err;
err = btf_func_check(env, t);
if (err)
return err;
env_stack_pop_resolved(env, next_type_id, 0);
return 0;
}
static struct btf_kind_operations func_ops = {
.check_meta = btf_func_check_meta,
.resolve = btf_func_resolve,
.check_member = btf_df_check_member,
.check_kflag_member = btf_df_check_kflag_member,
.log_details = btf_ref_type_log,
.show = btf_df_show,
};
static s32 btf_var_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
const struct btf_var *var;
u32 meta_needed = sizeof(*var);
if (meta_left < meta_needed) {
btf_verifier_log_basic(env, t,
"meta_left:%u meta_needed:%u",
meta_left, meta_needed);
return -EINVAL;
}
if (btf_type_vlen(t)) {
btf_verifier_log_type(env, t, "vlen != 0");
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
if (!t->name_off ||
!__btf_name_valid(env->btf, t->name_off, true)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
/* A var cannot be in type void */
if (!t->type || !BTF_TYPE_ID_VALID(t->type)) {
btf_verifier_log_type(env, t, "Invalid type_id");
return -EINVAL;
}
var = btf_type_var(t);
if (var->linkage != BTF_VAR_STATIC &&
var->linkage != BTF_VAR_GLOBAL_ALLOCATED) {
btf_verifier_log_type(env, t, "Linkage not supported");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
return meta_needed;
}
static void btf_var_log(struct btf_verifier_env *env, const struct btf_type *t)
{
const struct btf_var *var = btf_type_var(t);
btf_verifier_log(env, "type_id=%u linkage=%u", t->type, var->linkage);
}
static const struct btf_kind_operations var_ops = {
.check_meta = btf_var_check_meta,
.resolve = btf_var_resolve,
.check_member = btf_df_check_member,
.check_kflag_member = btf_df_check_kflag_member,
.log_details = btf_var_log,
.show = btf_var_show,
};
static s32 btf_datasec_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
const struct btf_var_secinfo *vsi;
u64 last_vsi_end_off = 0, sum = 0;
u32 i, meta_needed;
meta_needed = btf_type_vlen(t) * sizeof(*vsi);
if (meta_left < meta_needed) {
btf_verifier_log_basic(env, t,
"meta_left:%u meta_needed:%u",
meta_left, meta_needed);
return -EINVAL;
}
if (!t->size) {
btf_verifier_log_type(env, t, "size == 0");
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
if (!t->name_off ||
!btf_name_valid_section(env->btf, t->name_off)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
for_each_vsi(i, t, vsi) {
/* A var cannot be in type void */
if (!vsi->type || !BTF_TYPE_ID_VALID(vsi->type)) {
btf_verifier_log_vsi(env, t, vsi,
"Invalid type_id");
return -EINVAL;
}
if (vsi->offset < last_vsi_end_off || vsi->offset >= t->size) {
btf_verifier_log_vsi(env, t, vsi,
"Invalid offset");
return -EINVAL;
}
if (!vsi->size || vsi->size > t->size) {
btf_verifier_log_vsi(env, t, vsi,
"Invalid size");
return -EINVAL;
}
last_vsi_end_off = vsi->offset + vsi->size;
if (last_vsi_end_off > t->size) {
btf_verifier_log_vsi(env, t, vsi,
"Invalid offset+size");
return -EINVAL;
}
btf_verifier_log_vsi(env, t, vsi, NULL);
sum += vsi->size;
}
if (t->size < sum) {
btf_verifier_log_type(env, t, "Invalid btf_info size");
return -EINVAL;
}
return meta_needed;
}
static int btf_datasec_resolve(struct btf_verifier_env *env,
const struct resolve_vertex *v)
{
const struct btf_var_secinfo *vsi;
struct btf *btf = env->btf;
u16 i;
for_each_vsi_from(i, v->next_member, v->t, vsi) {
u32 var_type_id = vsi->type, type_id, type_size = 0;
const struct btf_type *var_type = btf_type_by_id(env->btf,
var_type_id);
if (!var_type || !btf_type_is_var(var_type)) {
btf_verifier_log_vsi(env, v->t, vsi,
"Not a VAR kind member");
return -EINVAL;
}
if (!env_type_is_resolve_sink(env, var_type) &&
!env_type_is_resolved(env, var_type_id)) {
env_stack_set_next_member(env, i + 1);
return env_stack_push(env, var_type, var_type_id);
}
type_id = var_type->type;
if (!btf_type_id_size(btf, &type_id, &type_size)) {
btf_verifier_log_vsi(env, v->t, vsi, "Invalid type");
return -EINVAL;
}
if (vsi->size < type_size) {
btf_verifier_log_vsi(env, v->t, vsi, "Invalid size");
return -EINVAL;
}
}
env_stack_pop_resolved(env, 0, 0);
return 0;
}
static void btf_datasec_log(struct btf_verifier_env *env,
const struct btf_type *t)
{
btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
}
static void btf_datasec_show(const struct btf *btf,
const struct btf_type *t, u32 type_id,
void *data, u8 bits_offset,
struct btf_show *show)
{
const struct btf_var_secinfo *vsi;
const struct btf_type *var;
u32 i;
if (!btf_show_start_type(show, t, type_id, data))
return;
btf_show_type_value(show, "section (\"%s\") = {",
__btf_name_by_offset(btf, t->name_off));
for_each_vsi(i, t, vsi) {
var = btf_type_by_id(btf, vsi->type);
if (i)
btf_show(show, ",");
btf_type_ops(var)->show(btf, var, vsi->type,
data + vsi->offset, bits_offset, show);
}
btf_show_end_type(show);
}
static const struct btf_kind_operations datasec_ops = {
.check_meta = btf_datasec_check_meta,
.resolve = btf_datasec_resolve,
.check_member = btf_df_check_member,
.check_kflag_member = btf_df_check_kflag_member,
.log_details = btf_datasec_log,
.show = btf_datasec_show,
};
static s32 btf_float_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
if (btf_type_vlen(t)) {
btf_verifier_log_type(env, t, "vlen != 0");
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
if (t->size != 2 && t->size != 4 && t->size != 8 && t->size != 12 &&
t->size != 16) {
btf_verifier_log_type(env, t, "Invalid type_size");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
return 0;
}
static int btf_float_check_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
u64 start_offset_bytes;
u64 end_offset_bytes;
u64 misalign_bits;
u64 align_bytes;
u64 align_bits;
/* Different architectures have different alignment requirements, so
* here we check only for the reasonable minimum. This way we ensure
* that types after CO-RE can pass the kernel BTF verifier.
*/
align_bytes = min_t(u64, sizeof(void *), member_type->size);
align_bits = align_bytes * BITS_PER_BYTE;
div64_u64_rem(member->offset, align_bits, &misalign_bits);
if (misalign_bits) {
btf_verifier_log_member(env, struct_type, member,
"Member is not properly aligned");
return -EINVAL;
}
start_offset_bytes = member->offset / BITS_PER_BYTE;
end_offset_bytes = start_offset_bytes + member_type->size;
if (end_offset_bytes > struct_type->size) {
btf_verifier_log_member(env, struct_type, member,
"Member exceeds struct_size");
return -EINVAL;
}
return 0;
}
static void btf_float_log(struct btf_verifier_env *env,
const struct btf_type *t)
{
btf_verifier_log(env, "size=%u", t->size);
}
static const struct btf_kind_operations float_ops = {
.check_meta = btf_float_check_meta,
.resolve = btf_df_resolve,
.check_member = btf_float_check_member,
.check_kflag_member = btf_generic_check_kflag_member,
.log_details = btf_float_log,
.show = btf_df_show,
};
static s32 btf_decl_tag_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
const struct btf_decl_tag *tag;
u32 meta_needed = sizeof(*tag);
s32 component_idx;
const char *value;
if (meta_left < meta_needed) {
btf_verifier_log_basic(env, t,
"meta_left:%u meta_needed:%u",
meta_left, meta_needed);
return -EINVAL;
}
value = btf_name_by_offset(env->btf, t->name_off);
if (!value || !value[0]) {
btf_verifier_log_type(env, t, "Invalid value");
return -EINVAL;
}
if (btf_type_vlen(t)) {
btf_verifier_log_type(env, t, "vlen != 0");
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
component_idx = btf_type_decl_tag(t)->component_idx;
if (component_idx < -1) {
btf_verifier_log_type(env, t, "Invalid component_idx");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
return meta_needed;
}
static int btf_decl_tag_resolve(struct btf_verifier_env *env,
const struct resolve_vertex *v)
{
const struct btf_type *next_type;
const struct btf_type *t = v->t;
u32 next_type_id = t->type;
struct btf *btf = env->btf;
s32 component_idx;
u32 vlen;
next_type = btf_type_by_id(btf, next_type_id);
if (!next_type || !btf_type_is_decl_tag_target(next_type)) {
btf_verifier_log_type(env, v->t, "Invalid type_id");
return -EINVAL;
}
if (!env_type_is_resolve_sink(env, next_type) &&
!env_type_is_resolved(env, next_type_id))
return env_stack_push(env, next_type, next_type_id);
component_idx = btf_type_decl_tag(t)->component_idx;
if (component_idx != -1) {
if (btf_type_is_var(next_type) || btf_type_is_typedef(next_type)) {
btf_verifier_log_type(env, v->t, "Invalid component_idx");
return -EINVAL;
}
if (btf_type_is_struct(next_type)) {
vlen = btf_type_vlen(next_type);
} else {
/* next_type should be a function */
next_type = btf_type_by_id(btf, next_type->type);
vlen = btf_type_vlen(next_type);
}
if ((u32)component_idx >= vlen) {
btf_verifier_log_type(env, v->t, "Invalid component_idx");
return -EINVAL;
}
}
env_stack_pop_resolved(env, next_type_id, 0);
return 0;
}
static void btf_decl_tag_log(struct btf_verifier_env *env, const struct btf_type *t)
{
btf_verifier_log(env, "type=%u component_idx=%d", t->type,
btf_type_decl_tag(t)->component_idx);
}
static const struct btf_kind_operations decl_tag_ops = {
.check_meta = btf_decl_tag_check_meta,
.resolve = btf_decl_tag_resolve,
.check_member = btf_df_check_member,
.check_kflag_member = btf_df_check_kflag_member,
.log_details = btf_decl_tag_log,
.show = btf_df_show,
};
static int btf_func_proto_check(struct btf_verifier_env *env,
const struct btf_type *t)
{
const struct btf_type *ret_type;
const struct btf_param *args;
const struct btf *btf;
u16 nr_args, i;
int err;
btf = env->btf;
args = (const struct btf_param *)(t + 1);
nr_args = btf_type_vlen(t);
/* Check func return type which could be "void" (t->type == 0) */
if (t->type) {
u32 ret_type_id = t->type;
ret_type = btf_type_by_id(btf, ret_type_id);
if (!ret_type) {
btf_verifier_log_type(env, t, "Invalid return type");
return -EINVAL;
}
if (btf_type_needs_resolve(ret_type) &&
!env_type_is_resolved(env, ret_type_id)) {
err = btf_resolve(env, ret_type, ret_type_id);
if (err)
return err;
}
/* Ensure the return type is a type that has a size */
if (!btf_type_id_size(btf, &ret_type_id, NULL)) {
btf_verifier_log_type(env, t, "Invalid return type");
return -EINVAL;
}
}
if (!nr_args)
return 0;
/* Last func arg type_id could be 0 if it is a vararg */
if (!args[nr_args - 1].type) {
if (args[nr_args - 1].name_off) {
btf_verifier_log_type(env, t, "Invalid arg#%u",
nr_args);
return -EINVAL;
}
nr_args--;
}
err = 0;
for (i = 0; i < nr_args; i++) {
const struct btf_type *arg_type;
u32 arg_type_id;
arg_type_id = args[i].type;
arg_type = btf_type_by_id(btf, arg_type_id);
if (!arg_type) {
btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
err = -EINVAL;
break;
}
if (args[i].name_off &&
(!btf_name_offset_valid(btf, args[i].name_off) ||
!btf_name_valid_identifier(btf, args[i].name_off))) {
btf_verifier_log_type(env, t,
"Invalid arg#%u", i + 1);
err = -EINVAL;
break;
}
if (btf_type_needs_resolve(arg_type) &&
!env_type_is_resolved(env, arg_type_id)) {
err = btf_resolve(env, arg_type, arg_type_id);
if (err)
break;
}
if (!btf_type_id_size(btf, &arg_type_id, NULL)) {
btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
err = -EINVAL;
break;
}
}
return err;
}
static int btf_func_check(struct btf_verifier_env *env,
const struct btf_type *t)
{
const struct btf_type *proto_type;
const struct btf_param *args;
const struct btf *btf;
u16 nr_args, i;
btf = env->btf;
proto_type = btf_type_by_id(btf, t->type);
if (!proto_type || !btf_type_is_func_proto(proto_type)) {
btf_verifier_log_type(env, t, "Invalid type_id");
return -EINVAL;
}
args = (const struct btf_param *)(proto_type + 1);
nr_args = btf_type_vlen(proto_type);
for (i = 0; i < nr_args; i++) {
if (!args[i].name_off && args[i].type) {
btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
return -EINVAL;
}
}
return 0;
}
static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS] = {
[BTF_KIND_INT] = &int_ops,
[BTF_KIND_PTR] = &ptr_ops,
[BTF_KIND_ARRAY] = &array_ops,
[BTF_KIND_STRUCT] = &struct_ops,
[BTF_KIND_UNION] = &struct_ops,
[BTF_KIND_ENUM] = &enum_ops,
[BTF_KIND_FWD] = &fwd_ops,
[BTF_KIND_TYPEDEF] = &modifier_ops,
[BTF_KIND_VOLATILE] = &modifier_ops,
[BTF_KIND_CONST] = &modifier_ops,
[BTF_KIND_RESTRICT] = &modifier_ops,
[BTF_KIND_FUNC] = &func_ops,
[BTF_KIND_FUNC_PROTO] = &func_proto_ops,
[BTF_KIND_VAR] = &var_ops,
[BTF_KIND_DATASEC] = &datasec_ops,
[BTF_KIND_FLOAT] = &float_ops,
[BTF_KIND_DECL_TAG] = &decl_tag_ops,
[BTF_KIND_TYPE_TAG] = &modifier_ops,
};
static s32 btf_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
u32 saved_meta_left = meta_left;
s32 var_meta_size;
if (meta_left < sizeof(*t)) {
btf_verifier_log(env, "[%u] meta_left:%u meta_needed:%zu",
env->log_type_id, meta_left, sizeof(*t));
return -EINVAL;
}
meta_left -= sizeof(*t);
if (t->info & ~BTF_INFO_MASK) {
btf_verifier_log(env, "[%u] Invalid btf_info:%x",
env->log_type_id, t->info);
return -EINVAL;
}
if (BTF_INFO_KIND(t->info) > BTF_KIND_MAX ||
BTF_INFO_KIND(t->info) == BTF_KIND_UNKN) {
btf_verifier_log(env, "[%u] Invalid kind:%u",
env->log_type_id, BTF_INFO_KIND(t->info));
return -EINVAL;
}
if (!btf_name_offset_valid(env->btf, t->name_off)) {
btf_verifier_log(env, "[%u] Invalid name_offset:%u",
env->log_type_id, t->name_off);
return -EINVAL;
}
var_meta_size = btf_type_ops(t)->check_meta(env, t, meta_left);
if (var_meta_size < 0)
return var_meta_size;
meta_left -= var_meta_size;
return saved_meta_left - meta_left;
}
static int btf_check_all_metas(struct btf_verifier_env *env)
{
struct btf *btf = env->btf;
struct btf_header *hdr;
void *cur, *end;
hdr = &btf->hdr;
cur = btf->nohdr_data + hdr->type_off;
end = cur + hdr->type_len;
env->log_type_id = btf->base_btf ? btf->start_id : 1;
while (cur < end) {
struct btf_type *t = cur;
s32 meta_size;
meta_size = btf_check_meta(env, t, end - cur);
if (meta_size < 0)
return meta_size;
btf_add_type(env, t);
cur += meta_size;
env->log_type_id++;
}
return 0;
}
static bool btf_resolve_valid(struct btf_verifier_env *env,
const struct btf_type *t,
u32 type_id)
{
struct btf *btf = env->btf;
if (!env_type_is_resolved(env, type_id))
return false;
if (btf_type_is_struct(t) || btf_type_is_datasec(t))
return !btf_resolved_type_id(btf, type_id) &&
!btf_resolved_type_size(btf, type_id);
if (btf_type_is_decl_tag(t) || btf_type_is_func(t))
return btf_resolved_type_id(btf, type_id) &&
!btf_resolved_type_size(btf, type_id);
if (btf_type_is_modifier(t) || btf_type_is_ptr(t) ||
btf_type_is_var(t)) {
t = btf_type_id_resolve(btf, &type_id);
return t &&
!btf_type_is_modifier(t) &&
!btf_type_is_var(t) &&
!btf_type_is_datasec(t);
}
if (btf_type_is_array(t)) {
const struct btf_array *array = btf_type_array(t);
const struct btf_type *elem_type;
u32 elem_type_id = array->type;
u32 elem_size;
elem_type = btf_type_id_size(btf, &elem_type_id, &elem_size);
return elem_type && !btf_type_is_modifier(elem_type) &&
(array->nelems * elem_size ==
btf_resolved_type_size(btf, type_id));
}
return false;
}
static int btf_resolve(struct btf_verifier_env *env,
const struct btf_type *t, u32 type_id)
{
u32 save_log_type_id = env->log_type_id;
const struct resolve_vertex *v;
int err = 0;
env->resolve_mode = RESOLVE_TBD;
env_stack_push(env, t, type_id);
while (!err && (v = env_stack_peak(env))) {
env->log_type_id = v->type_id;
err = btf_type_ops(v->t)->resolve(env, v);
}
env->log_type_id = type_id;
if (err == -E2BIG) {
btf_verifier_log_type(env, t,
"Exceeded max resolving depth:%u",
MAX_RESOLVE_DEPTH);
} else if (err == -EEXIST) {
btf_verifier_log_type(env, t, "Loop detected");
}
/* Final sanity check */
if (!err && !btf_resolve_valid(env, t, type_id)) {
btf_verifier_log_type(env, t, "Invalid resolve state");
err = -EINVAL;
}
env->log_type_id = save_log_type_id;
return err;
}
static int btf_check_all_types(struct btf_verifier_env *env)
{
struct btf *btf = env->btf;
const struct btf_type *t;
u32 type_id, i;
int err;
err = env_resolve_init(env);
if (err)
return err;
env->phase++;
for (i = btf->base_btf ? 0 : 1; i < btf->nr_types; i++) {
type_id = btf->start_id + i;
t = btf_type_by_id(btf, type_id);
env->log_type_id = type_id;
if (btf_type_needs_resolve(t) &&
!env_type_is_resolved(env, type_id)) {
err = btf_resolve(env, t, type_id);
if (err)
return err;
}
if (btf_type_is_func_proto(t)) {
err = btf_func_proto_check(env, t);
if (err)
return err;
}
}
return 0;
}
static int btf_parse_type_sec(struct btf_verifier_env *env)
{
const struct btf_header *hdr = &env->btf->hdr;
int err;
/* Type section must align to 4 bytes */
if (hdr->type_off & (sizeof(u32) - 1)) {
btf_verifier_log(env, "Unaligned type_off");
return -EINVAL;
}
if (!env->btf->base_btf && !hdr->type_len) {
btf_verifier_log(env, "No type found");
return -EINVAL;
}
err = btf_check_all_metas(env);
if (err)
return err;
return btf_check_all_types(env);
}
static int btf_parse_str_sec(struct btf_verifier_env *env)
{
const struct btf_header *hdr;
struct btf *btf = env->btf;
const char *start, *end;
hdr = &btf->hdr;
start = btf->nohdr_data + hdr->str_off;
end = start + hdr->str_len;
if (end != btf->data + btf->data_size) {
btf_verifier_log(env, "String section is not at the end");
return -EINVAL;
}
btf->strings = start;
if (btf->base_btf && !hdr->str_len)
return 0;
if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_NAME_OFFSET || end[-1]) {
btf_verifier_log(env, "Invalid string section");
return -EINVAL;
}
if (!btf->base_btf && start[0]) {
btf_verifier_log(env, "Invalid string section");
return -EINVAL;
}
return 0;
}
static const size_t btf_sec_info_offset[] = {
offsetof(struct btf_header, type_off),
offsetof(struct btf_header, str_off),
};
static int btf_sec_info_cmp(const void *a, const void *b)
{
const struct btf_sec_info *x = a;
const struct btf_sec_info *y = b;
return (int)(x->off - y->off) ? : (int)(x->len - y->len);
}
static int btf_check_sec_info(struct btf_verifier_env *env,
u32 btf_data_size)
{
struct btf_sec_info secs[ARRAY_SIZE(btf_sec_info_offset)];
u32 total, expected_total, i;
const struct btf_header *hdr;
const struct btf *btf;
btf = env->btf;
hdr = &btf->hdr;
/* Populate the secs from hdr */
for (i = 0; i < ARRAY_SIZE(btf_sec_info_offset); i++)
secs[i] = *(struct btf_sec_info *)((void *)hdr +
btf_sec_info_offset[i]);
sort(secs, ARRAY_SIZE(btf_sec_info_offset),
sizeof(struct btf_sec_info), btf_sec_info_cmp, NULL);
/* Check for gaps and overlap among sections */
total = 0;
expected_total = btf_data_size - hdr->hdr_len;
for (i = 0; i < ARRAY_SIZE(btf_sec_info_offset); i++) {
if (expected_total < secs[i].off) {
btf_verifier_log(env, "Invalid section offset");
return -EINVAL;
}
if (total < secs[i].off) {
/* gap */
btf_verifier_log(env, "Unsupported section found");
return -EINVAL;
}
if (total > secs[i].off) {
btf_verifier_log(env, "Section overlap found");
return -EINVAL;
}
if (expected_total - total < secs[i].len) {
btf_verifier_log(env,
"Total section length too long");
return -EINVAL;
}
total += secs[i].len;
}
/* There is data other than hdr and known sections */
if (expected_total != total) {
btf_verifier_log(env, "Unsupported section found");
return -EINVAL;
}
return 0;
}
static int btf_parse_hdr(struct btf_verifier_env *env)
{
u32 hdr_len, hdr_copy, btf_data_size;
const struct btf_header *hdr;
struct btf *btf;
int err;
btf = env->btf;
btf_data_size = btf->data_size;
if (btf_data_size < offsetofend(struct btf_header, hdr_len)) {
btf_verifier_log(env, "hdr_len not found");
return -EINVAL;
}
hdr = btf->data;
hdr_len = hdr->hdr_len;
if (btf_data_size < hdr_len) {
btf_verifier_log(env, "btf_header not found");
return -EINVAL;
}
/* Ensure the unsupported header fields are zero */
if (hdr_len > sizeof(btf->hdr)) {
u8 *expected_zero = btf->data + sizeof(btf->hdr);
u8 *end = btf->data + hdr_len;
for (; expected_zero < end; expected_zero++) {
if (*expected_zero) {
btf_verifier_log(env, "Unsupported btf_header");
return -E2BIG;
}
}
}
hdr_copy = min_t(u32, hdr_len, sizeof(btf->hdr));
memcpy(&btf->hdr, btf->data, hdr_copy);
hdr = &btf->hdr;
btf_verifier_log_hdr(env, btf_data_size);
if (hdr->magic != BTF_MAGIC) {
btf_verifier_log(env, "Invalid magic");
return -EINVAL;
}
if (hdr->version != BTF_VERSION) {
btf_verifier_log(env, "Unsupported version");
return -ENOTSUPP;
}
if (hdr->flags) {
btf_verifier_log(env, "Unsupported flags");
return -ENOTSUPP;
}
if (!btf->base_btf && btf_data_size == hdr->hdr_len) {
btf_verifier_log(env, "No data");
return -EINVAL;
}
err = btf_check_sec_info(env, btf_data_size);
if (err)
return err;
return 0;
}
static int btf_check_type_tags(struct btf_verifier_env *env,
struct btf *btf, int start_id)
{
int i, n, good_id = start_id - 1;
bool in_tags;
n = btf_nr_types(btf);
for (i = start_id; i < n; i++) {
const struct btf_type *t;
u32 cur_id = i;
t = btf_type_by_id(btf, i);
if (!t)
return -EINVAL;
if (!btf_type_is_modifier(t))
continue;
cond_resched();
in_tags = btf_type_is_type_tag(t);
while (btf_type_is_modifier(t)) {
if (btf_type_is_type_tag(t)) {
if (!in_tags) {
btf_verifier_log(env, "Type tags don't precede modifiers");
return -EINVAL;
}
} else if (in_tags) {
in_tags = false;
}
if (cur_id <= good_id)
break;
/* Move to next type */
cur_id = t->type;
t = btf_type_by_id(btf, cur_id);
if (!t)
return -EINVAL;
}
good_id = i;
}
return 0;
}
static struct btf *btf_parse(bpfptr_t btf_data, u32 btf_data_size,
u32 log_level, char __user *log_ubuf, u32 log_size)
{
struct btf_verifier_env *env = NULL;
struct bpf_verifier_log *log;
struct btf *btf = NULL;
u8 *data;
int err;
if (btf_data_size > BTF_MAX_SIZE)
return ERR_PTR(-E2BIG);
env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
if (!env)
return ERR_PTR(-ENOMEM);
log = &env->log;
if (log_level || log_ubuf || log_size) {
/* user requested verbose verifier output
* and supplied buffer to store the verification trace
*/
log->level = log_level;
log->ubuf = log_ubuf;
log->len_total = log_size;
/* log attributes have to be sane */
if (!bpf_verifier_log_attr_valid(log)) {
err = -EINVAL;
goto errout;
}
}
btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
if (!btf) {
err = -ENOMEM;
goto errout;
}
env->btf = btf;
data = kvmalloc(btf_data_size, GFP_KERNEL | __GFP_NOWARN);
if (!data) {
err = -ENOMEM;
goto errout;
}
btf->data = data;
btf->data_size = btf_data_size;
if (copy_from_bpfptr(data, btf_data, btf_data_size)) {
err = -EFAULT;
goto errout;
}
err = btf_parse_hdr(env);
if (err)
goto errout;
btf->nohdr_data = btf->data + btf->hdr.hdr_len;
err = btf_parse_str_sec(env);
if (err)
goto errout;
err = btf_parse_type_sec(env);
if (err)
goto errout;
err = btf_check_type_tags(env, btf, 1);
if (err)
goto errout;
if (log->level && bpf_verifier_log_full(log)) {
err = -ENOSPC;
goto errout;
}
btf_verifier_env_free(env);
refcount_set(&btf->refcnt, 1);
return btf;
errout:
btf_verifier_env_free(env);
if (btf)
btf_free(btf);
return ERR_PTR(err);
}
extern char __weak __start_BTF[];
extern char __weak __stop_BTF[];
extern struct btf *btf_vmlinux;
#define BPF_MAP_TYPE(_id, _ops)
#define BPF_LINK_TYPE(_id, _name)
static union {
struct bpf_ctx_convert {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
prog_ctx_type _id##_prog; \
kern_ctx_type _id##_kern;
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
} *__t;
/* 't' is written once under lock. Read many times. */
const struct btf_type *t;
} bpf_ctx_convert;
enum {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
__ctx_convert##_id,
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
__ctx_convert_unused, /* to avoid empty enum in extreme .config */
};
static u8 bpf_ctx_convert_map[] = {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
[_id] = __ctx_convert##_id,
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
0, /* avoid empty array */
};
#undef BPF_MAP_TYPE
#undef BPF_LINK_TYPE
static const struct btf_member *
btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
const struct btf_type *t, enum bpf_prog_type prog_type,
int arg)
{
const struct btf_type *conv_struct;
const struct btf_type *ctx_struct;
const struct btf_member *ctx_type;
const char *tname, *ctx_tname;
conv_struct = bpf_ctx_convert.t;
if (!conv_struct) {
bpf_log(log, "btf_vmlinux is malformed\n");
return NULL;
}
t = btf_type_by_id(btf, t->type);
while (btf_type_is_modifier(t))
t = btf_type_by_id(btf, t->type);
if (!btf_type_is_struct(t)) {
/* Only pointer to struct is supported for now.
* That means that BPF_PROG_TYPE_TRACEPOINT with BTF
* is not supported yet.
* BPF_PROG_TYPE_RAW_TRACEPOINT is fine.
*/
return NULL;
}
tname = btf_name_by_offset(btf, t->name_off);
if (!tname) {
bpf_log(log, "arg#%d struct doesn't have a name\n", arg);
return NULL;
}
/* prog_type is valid bpf program type. No need for bounds check. */
ctx_type = btf_type_member(conv_struct) + bpf_ctx_convert_map[prog_type] * 2;
/* ctx_struct is a pointer to prog_ctx_type in vmlinux.
* Like 'struct __sk_buff'
*/
ctx_struct = btf_type_by_id(btf_vmlinux, ctx_type->type);
if (!ctx_struct)
/* should not happen */
return NULL;
ctx_tname = btf_name_by_offset(btf_vmlinux, ctx_struct->name_off);
if (!ctx_tname) {
/* should not happen */
bpf_log(log, "Please fix kernel include/linux/bpf_types.h\n");
return NULL;
}
/* only compare that prog's ctx type name is the same as
* kernel expects. No need to compare field by field.
* It's ok for bpf prog to do:
* struct __sk_buff {};
* int socket_filter_bpf_prog(struct __sk_buff *skb)
* { // no fields of skb are ever used }
*/
if (strcmp(ctx_tname, tname))
return NULL;
return ctx_type;
}
static int btf_translate_to_vmlinux(struct bpf_verifier_log *log,
struct btf *btf,
const struct btf_type *t,
enum bpf_prog_type prog_type,
int arg)
{
const struct btf_member *prog_ctx_type, *kern_ctx_type;
prog_ctx_type = btf_get_prog_ctx_type(log, btf, t, prog_type, arg);
if (!prog_ctx_type)
return -ENOENT;
kern_ctx_type = prog_ctx_type + 1;
return kern_ctx_type->type;
}
BTF_ID_LIST(bpf_ctx_convert_btf_id)
BTF_ID(struct, bpf_ctx_convert)
struct btf *btf_parse_vmlinux(void)
{
struct btf_verifier_env *env = NULL;
struct bpf_verifier_log *log;
struct btf *btf = NULL;
int err;
env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
if (!env)
return ERR_PTR(-ENOMEM);
log = &env->log;
log->level = BPF_LOG_KERNEL;
btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
if (!btf) {
err = -ENOMEM;
goto errout;
}
env->btf = btf;
btf->data = __start_BTF;
btf->data_size = __stop_BTF - __start_BTF;
btf->kernel_btf = true;
snprintf(btf->name, sizeof(btf->name), "vmlinux");
err = btf_parse_hdr(env);
if (err)
goto errout;
btf->nohdr_data = btf->data + btf->hdr.hdr_len;
err = btf_parse_str_sec(env);
if (err)
goto errout;
err = btf_check_all_metas(env);
if (err)
goto errout;
err = btf_check_type_tags(env, btf, 1);
if (err)
goto errout;
/* btf_parse_vmlinux() runs under bpf_verifier_lock */
bpf_ctx_convert.t = btf_type_by_id(btf, bpf_ctx_convert_btf_id[0]);
bpf_struct_ops_init(btf, log);
refcount_set(&btf->refcnt, 1);
err = btf_alloc_id(btf);
if (err)
goto errout;
btf_verifier_env_free(env);
return btf;
errout:
btf_verifier_env_free(env);
if (btf) {
kvfree(btf->types);
kfree(btf);
}
return ERR_PTR(err);
}
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
static struct btf *btf_parse_module(const char *module_name, const void *data, unsigned int data_size)
{
struct btf_verifier_env *env = NULL;
struct bpf_verifier_log *log;
struct btf *btf = NULL, *base_btf;
int err;
base_btf = bpf_get_btf_vmlinux();
if (IS_ERR(base_btf))
return base_btf;
if (!base_btf)
return ERR_PTR(-EINVAL);
env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
if (!env)
return ERR_PTR(-ENOMEM);
log = &env->log;
log->level = BPF_LOG_KERNEL;
btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
if (!btf) {
err = -ENOMEM;
goto errout;
}
env->btf = btf;
btf->base_btf = base_btf;
btf->start_id = base_btf->nr_types;
btf->start_str_off = base_btf->hdr.str_len;
btf->kernel_btf = true;
snprintf(btf->name, sizeof(btf->name), "%s", module_name);
btf->data = kvmalloc(data_size, GFP_KERNEL | __GFP_NOWARN);
if (!btf->data) {
err = -ENOMEM;
goto errout;
}
memcpy(btf->data, data, data_size);
btf->data_size = data_size;
err = btf_parse_hdr(env);
if (err)
goto errout;
btf->nohdr_data = btf->data + btf->hdr.hdr_len;
err = btf_parse_str_sec(env);
if (err)
goto errout;
err = btf_check_all_metas(env);
if (err)
goto errout;
err = btf_check_type_tags(env, btf, btf_nr_types(base_btf));
if (err)
goto errout;
btf_verifier_env_free(env);
refcount_set(&btf->refcnt, 1);
return btf;
errout:
btf_verifier_env_free(env);
if (btf) {
kvfree(btf->data);
kvfree(btf->types);
kfree(btf);
}
return ERR_PTR(err);
}
#endif /* CONFIG_DEBUG_INFO_BTF_MODULES */
struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog)
{
struct bpf_prog *tgt_prog = prog->aux->dst_prog;
if (tgt_prog)
return tgt_prog->aux->btf;
else
return prog->aux->attach_btf;
}
static bool is_int_ptr(struct btf *btf, const struct btf_type *t)
{
/* t comes in already as a pointer */
t = btf_type_by_id(btf, t->type);
/* allow const */
if (BTF_INFO_KIND(t->info) == BTF_KIND_CONST)
t = btf_type_by_id(btf, t->type);
return btf_type_is_int(t);
}
bool btf_ctx_access(int off, int size, enum bpf_access_type type,
const struct bpf_prog *prog,
struct bpf_insn_access_aux *info)
{
const struct btf_type *t = prog->aux->attach_func_proto;
struct bpf_prog *tgt_prog = prog->aux->dst_prog;
struct btf *btf = bpf_prog_get_target_btf(prog);
const char *tname = prog->aux->attach_func_name;
struct bpf_verifier_log *log = info->log;
const struct btf_param *args;
const char *tag_value;
u32 nr_args, arg;
int i, ret;
if (off % 8) {
bpf_log(log, "func '%s' offset %d is not multiple of 8\n",
tname, off);
return false;
}
arg = off / 8;
args = (const struct btf_param *)(t + 1);
/* if (t == NULL) Fall back to default BPF prog with
* MAX_BPF_FUNC_REG_ARGS u64 arguments.
*/
nr_args = t ? btf_type_vlen(t) : MAX_BPF_FUNC_REG_ARGS;
if (prog->aux->attach_btf_trace) {
/* skip first 'void *__data' argument in btf_trace_##name typedef */
args++;
nr_args--;
}
if (arg > nr_args) {
bpf_log(log, "func '%s' doesn't have %d-th argument\n",
tname, arg + 1);
return false;
}
if (arg == nr_args) {
switch (prog->expected_attach_type) {
case BPF_LSM_MAC:
case BPF_TRACE_FEXIT:
/* When LSM programs are attached to void LSM hooks
* they use FEXIT trampolines and when attached to
* int LSM hooks, they use MODIFY_RETURN trampolines.
*
* While the LSM programs are BPF_MODIFY_RETURN-like
* the check:
*
* if (ret_type != 'int')
* return -EINVAL;
*
* is _not_ done here. This is still safe as LSM hooks
* have only void and int return types.
*/
if (!t)
return true;
t = btf_type_by_id(btf, t->type);
break;
case BPF_MODIFY_RETURN:
/* For now the BPF_MODIFY_RETURN can only be attached to
* functions that return an int.
*/
if (!t)
return false;
t = btf_type_skip_modifiers(btf, t->type, NULL);
if (!btf_type_is_small_int(t)) {
bpf_log(log,
"ret type %s not allowed for fmod_ret\n",
btf_kind_str[BTF_INFO_KIND(t->info)]);
return false;
}
break;
default:
bpf_log(log, "func '%s' doesn't have %d-th argument\n",
tname, arg + 1);
return false;
}
} else {
if (!t)
/* Default prog with MAX_BPF_FUNC_REG_ARGS args */
return true;
t = btf_type_by_id(btf, args[arg].type);
}
/* skip modifiers */
while (btf_type_is_modifier(t))
t = btf_type_by_id(btf, t->type);
if (btf_type_is_small_int(t) || btf_type_is_enum(t))
/* accessing a scalar */
return true;
if (!btf_type_is_ptr(t)) {
bpf_log(log,
"func '%s' arg%d '%s' has type %s. Only pointer access is allowed\n",
tname, arg,
__btf_name_by_offset(btf, t->name_off),
btf_kind_str[BTF_INFO_KIND(t->info)]);
return false;
}
/* check for PTR_TO_RDONLY_BUF_OR_NULL or PTR_TO_RDWR_BUF_OR_NULL */
for (i = 0; i < prog->aux->ctx_arg_info_size; i++) {
const struct bpf_ctx_arg_aux *ctx_arg_info = &prog->aux->ctx_arg_info[i];
u32 type, flag;
type = base_type(ctx_arg_info->reg_type);
flag = type_flag(ctx_arg_info->reg_type);
if (ctx_arg_info->offset == off && type == PTR_TO_BUF &&
(flag & PTR_MAYBE_NULL)) {
info->reg_type = ctx_arg_info->reg_type;
return true;
}
}
if (t->type == 0)
/* This is a pointer to void.
* It is the same as scalar from the verifier safety pov.
* No further pointer walking is allowed.
*/
return true;
if (is_int_ptr(btf, t))
return true;
/* this is a pointer to another type */
for (i = 0; i < prog->aux->ctx_arg_info_size; i++) {
const struct bpf_ctx_arg_aux *ctx_arg_info = &prog->aux->ctx_arg_info[i];
if (ctx_arg_info->offset == off) {
if (!ctx_arg_info->btf_id) {
bpf_log(log,"invalid btf_id for context argument offset %u\n", off);
return false;
}
info->reg_type = ctx_arg_info->reg_type;
info->btf = btf_vmlinux;
info->btf_id = ctx_arg_info->btf_id;
return true;
}
}
info->reg_type = PTR_TO_BTF_ID;
if (tgt_prog) {
enum bpf_prog_type tgt_type;
if (tgt_prog->type == BPF_PROG_TYPE_EXT)
tgt_type = tgt_prog->aux->saved_dst_prog_type;
else
tgt_type = tgt_prog->type;
ret = btf_translate_to_vmlinux(log, btf, t, tgt_type, arg);
if (ret > 0) {
info->btf = btf_vmlinux;
info->btf_id = ret;
return true;
} else {
return false;
}
}
info->btf = btf;
info->btf_id = t->type;
t = btf_type_by_id(btf, t->type);
if (btf_type_is_type_tag(t)) {
tag_value = __btf_name_by_offset(btf, t->name_off);
if (strcmp(tag_value, "user") == 0)
info->reg_type |= MEM_USER;
if (strcmp(tag_value, "percpu") == 0)
info->reg_type |= MEM_PERCPU;
}
/* skip modifiers */
while (btf_type_is_modifier(t)) {
info->btf_id = t->type;
t = btf_type_by_id(btf, t->type);
}
if (!btf_type_is_struct(t)) {
bpf_log(log,
"func '%s' arg%d type %s is not a struct\n",
tname, arg, btf_kind_str[BTF_INFO_KIND(t->info)]);
return false;
}
bpf_log(log, "func '%s' arg%d has btf_id %d type %s '%s'\n",
tname, arg, info->btf_id, btf_kind_str[BTF_INFO_KIND(t->info)],
__btf_name_by_offset(btf, t->name_off));
return true;
}
enum bpf_struct_walk_result {
/* < 0 error */
WALK_SCALAR = 0,
WALK_PTR,
WALK_STRUCT,
};
static int btf_struct_walk(struct bpf_verifier_log *log, const struct btf *btf,
const struct btf_type *t, int off, int size,
u32 *next_btf_id, enum bpf_type_flag *flag)
{
u32 i, moff, mtrue_end, msize = 0, total_nelems = 0;
const struct btf_type *mtype, *elem_type = NULL;
const struct btf_member *member;
const char *tname, *mname, *tag_value;
u32 vlen, elem_id, mid;
again:
tname = __btf_name_by_offset(btf, t->name_off);
if (!btf_type_is_struct(t)) {
bpf_log(log, "Type '%s' is not a struct\n", tname);
return -EINVAL;
}
vlen = btf_type_vlen(t);
if (off + size > t->size) {
/* If the last element is a variable size array, we may
* need to relax the rule.
*/
struct btf_array *array_elem;
if (vlen == 0)
goto error;
member = btf_type_member(t) + vlen - 1;
mtype = btf_type_skip_modifiers(btf, member->type,
NULL);
if (!btf_type_is_array(mtype))
goto error;
array_elem = (struct btf_array *)(mtype + 1);
if (array_elem->nelems != 0)
goto error;
moff = __btf_member_bit_offset(t, member) / 8;
if (off < moff)
goto error;
/* Only allow structure for now, can be relaxed for
* other types later.
*/
t = btf_type_skip_modifiers(btf, array_elem->type,
NULL);
if (!btf_type_is_struct(t))
goto error;
off = (off - moff) % t->size;
goto again;
error:
bpf_log(log, "access beyond struct %s at off %u size %u\n",
tname, off, size);
return -EACCES;
}
for_each_member(i, t, member) {
/* offset of the field in bytes */
moff = __btf_member_bit_offset(t, member) / 8;
if (off + size <= moff)
/* won't find anything, field is already too far */
break;
if (__btf_member_bitfield_size(t, member)) {
u32 end_bit = __btf_member_bit_offset(t, member) +
__btf_member_bitfield_size(t, member);
/* off <= moff instead of off == moff because clang
* does not generate a BTF member for anonymous
* bitfield like the ":16" here:
* struct {
* int :16;
* int x:8;
* };
*/
if (off <= moff &&
BITS_ROUNDUP_BYTES(end_bit) <= off + size)
return WALK_SCALAR;
/* off may be accessing a following member
*
* or
*
* Doing partial access at either end of this
* bitfield. Continue on this case also to
* treat it as not accessing this bitfield
* and eventually error out as field not
* found to keep it simple.
* It could be relaxed if there was a legit
* partial access case later.
*/
continue;
}
/* In case of "off" is pointing to holes of a struct */
if (off < moff)
break;
/* type of the field */
mid = member->type;
mtype = btf_type_by_id(btf, member->type);
mname = __btf_name_by_offset(btf, member->name_off);
mtype = __btf_resolve_size(btf, mtype, &msize,
&elem_type, &elem_id, &total_nelems,
&mid);
if (IS_ERR(mtype)) {
bpf_log(log, "field %s doesn't have size\n", mname);
return -EFAULT;
}
mtrue_end = moff + msize;
if (off >= mtrue_end)
/* no overlap with member, keep iterating */
continue;
if (btf_type_is_array(mtype)) {
u32 elem_idx;
/* __btf_resolve_size() above helps to
* linearize a multi-dimensional array.
*
* The logic here is treating an array
* in a struct as the following way:
*
* struct outer {
* struct inner array[2][2];
* };
*
* looks like:
*
* struct outer {
* struct inner array_elem0;
* struct inner array_elem1;
* struct inner array_elem2;
* struct inner array_elem3;
* };
*
* When accessing outer->array[1][0], it moves
* moff to "array_elem2", set mtype to
* "struct inner", and msize also becomes
* sizeof(struct inner). Then most of the
* remaining logic will fall through without
* caring the current member is an array or
* not.
*
* Unlike mtype/msize/moff, mtrue_end does not
* change. The naming difference ("_true") tells
* that it is not always corresponding to
* the current mtype/msize/moff.
* It is the true end of the current
* member (i.e. array in this case). That
* will allow an int array to be accessed like
* a scratch space,
* i.e. allow access beyond the size of
* the array's element as long as it is
* within the mtrue_end boundary.
*/
/* skip empty array */
if (moff == mtrue_end)
continue;
msize /= total_nelems;
elem_idx = (off - moff) / msize;
moff += elem_idx * msize;
mtype = elem_type;
mid = elem_id;
}
/* the 'off' we're looking for is either equal to start
* of this field or inside of this struct
*/
if (btf_type_is_struct(mtype)) {
/* our field must be inside that union or struct */
t = mtype;
/* return if the offset matches the member offset */
if (off == moff) {
*next_btf_id = mid;
return WALK_STRUCT;
}
/* adjust offset we're looking for */
off -= moff;
goto again;
}
if (btf_type_is_ptr(mtype)) {
const struct btf_type *stype, *t;
enum bpf_type_flag tmp_flag = 0;
u32 id;
if (msize != size || off != moff) {
bpf_log(log,
"cannot access ptr member %s with moff %u in struct %s with off %u size %u\n",
mname, moff, tname, off, size);
return -EACCES;
}
/* check type tag */
t = btf_type_by_id(btf, mtype->type);
if (btf_type_is_type_tag(t)) {
tag_value = __btf_name_by_offset(btf, t->name_off);
/* check __user tag */
if (strcmp(tag_value, "user") == 0)
tmp_flag = MEM_USER;
/* check __percpu tag */
if (strcmp(tag_value, "percpu") == 0)
tmp_flag = MEM_PERCPU;
}
stype = btf_type_skip_modifiers(btf, mtype->type, &id);
if (btf_type_is_struct(stype)) {
*next_btf_id = id;
*flag = tmp_flag;
return WALK_PTR;
}
}
/* Allow more flexible access within an int as long as
* it is within mtrue_end.
* Since mtrue_end could be the end of an array,
* that also allows using an array of int as a scratch
* space. e.g. skb->cb[].
*/
if (off + size > mtrue_end) {
bpf_log(log,
"access beyond the end of member %s (mend:%u) in struct %s with off %u size %u\n",
mname, mtrue_end, tname, off, size);
return -EACCES;
}
return WALK_SCALAR;
}
bpf_log(log, "struct %s doesn't have field at offset %d\n", tname, off);
return -EINVAL;
}
int btf_struct_access(struct bpf_verifier_log *log, const struct btf *btf,
const struct btf_type *t, int off, int size,
enum bpf_access_type atype __maybe_unused,
u32 *next_btf_id, enum bpf_type_flag *flag)
{
enum bpf_type_flag tmp_flag = 0;
int err;
u32 id;
do {
err = btf_struct_walk(log, btf, t, off, size, &id, &tmp_flag);
switch (err) {
case WALK_PTR:
/* If we found the pointer or scalar on t+off,
* we're done.
*/
*next_btf_id = id;
*flag = tmp_flag;
return PTR_TO_BTF_ID;
case WALK_SCALAR:
return SCALAR_VALUE;
case WALK_STRUCT:
/* We found nested struct, so continue the search
* by diving in it. At this point the offset is
* aligned with the new type, so set it to 0.
*/
t = btf_type_by_id(btf, id);
off = 0;
break;
default:
/* It's either error or unknown return value..
* scream and leave.
*/
if (WARN_ONCE(err > 0, "unknown btf_struct_walk return value"))
return -EINVAL;
return err;
}
} while (t);
return -EINVAL;
}
/* Check that two BTF types, each specified as an BTF object + id, are exactly
* the same. Trivial ID check is not enough due to module BTFs, because we can
* end up with two different module BTFs, but IDs point to the common type in
* vmlinux BTF.
*/
static bool btf_types_are_same(const struct btf *btf1, u32 id1,
const struct btf *btf2, u32 id2)
{
if (id1 != id2)
return false;
if (btf1 == btf2)
return true;
return btf_type_by_id(btf1, id1) == btf_type_by_id(btf2, id2);
}
bool btf_struct_ids_match(struct bpf_verifier_log *log,
const struct btf *btf, u32 id, int off,
const struct btf *need_btf, u32 need_type_id,
bool strict)
{
const struct btf_type *type;
enum bpf_type_flag flag;
int err;
/* Are we already done? */
if (off == 0 && btf_types_are_same(btf, id, need_btf, need_type_id))
return true;
/* In case of strict type match, we do not walk struct, the top level
* type match must succeed. When strict is true, off should have already
* been 0.
*/
if (strict)
return false;
again:
type = btf_type_by_id(btf, id);
if (!type)
return false;
err = btf_struct_walk(log, btf, type, off, 1, &id, &flag);
if (err != WALK_STRUCT)
return false;
/* We found nested struct object. If it matches
* the requested ID, we're done. Otherwise let's
* continue the search with offset 0 in the new
* type.
*/
if (!btf_types_are_same(btf, id, need_btf, need_type_id)) {
off = 0;
goto again;
}
return true;
}
static int __get_type_size(struct btf *btf, u32 btf_id,
const struct btf_type **bad_type)
{
const struct btf_type *t;
if (!btf_id)
/* void */
return 0;
t = btf_type_by_id(btf, btf_id);
while (t && btf_type_is_modifier(t))
t = btf_type_by_id(btf, t->type);
if (!t) {
*bad_type = btf_type_by_id(btf, 0);
return -EINVAL;
}
if (btf_type_is_ptr(t))
/* kernel size of pointer. Not BPF's size of pointer*/
return sizeof(void *);
if (btf_type_is_int(t) || btf_type_is_enum(t))
return t->size;
*bad_type = t;
return -EINVAL;
}
int btf_distill_func_proto(struct bpf_verifier_log *log,
struct btf *btf,
const struct btf_type *func,
const char *tname,
struct btf_func_model *m)
{
const struct btf_param *args;
const struct btf_type *t;
u32 i, nargs;
int ret;
if (!func) {
/* BTF function prototype doesn't match the verifier types.
* Fall back to MAX_BPF_FUNC_REG_ARGS u64 args.
*/
for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++)
m->arg_size[i] = 8;
m->ret_size = 8;
m->nr_args = MAX_BPF_FUNC_REG_ARGS;
return 0;
}
args = (const struct btf_param *)(func + 1);
nargs = btf_type_vlen(func);
if (nargs > MAX_BPF_FUNC_ARGS) {
bpf_log(log,
"The function %s has %d arguments. Too many.\n",
tname, nargs);
return -EINVAL;
}
ret = __get_type_size(btf, func->type, &t);
if (ret < 0) {
bpf_log(log,
"The function %s return type %s is unsupported.\n",
tname, btf_kind_str[BTF_INFO_KIND(t->info)]);
return -EINVAL;
}
m->ret_size = ret;
for (i = 0; i < nargs; i++) {
if (i == nargs - 1 && args[i].type == 0) {
bpf_log(log,
"The function %s with variable args is unsupported.\n",
tname);
return -EINVAL;
}
ret = __get_type_size(btf, args[i].type, &t);
if (ret < 0) {
bpf_log(log,
"The function %s arg%d type %s is unsupported.\n",
tname, i, btf_kind_str[BTF_INFO_KIND(t->info)]);
return -EINVAL;
}
if (ret == 0) {
bpf_log(log,
"The function %s has malformed void argument.\n",
tname);
return -EINVAL;
}
m->arg_size[i] = ret;
}
m->nr_args = nargs;
return 0;
}
/* Compare BTFs of two functions assuming only scalars and pointers to context.
* t1 points to BTF_KIND_FUNC in btf1
* t2 points to BTF_KIND_FUNC in btf2
* Returns:
* EINVAL - function prototype mismatch
* EFAULT - verifier bug
* 0 - 99% match. The last 1% is validated by the verifier.
*/
static int btf_check_func_type_match(struct bpf_verifier_log *log,
struct btf *btf1, const struct btf_type *t1,
struct btf *btf2, const struct btf_type *t2)
{
const struct btf_param *args1, *args2;
const char *fn1, *fn2, *s1, *s2;
u32 nargs1, nargs2, i;
fn1 = btf_name_by_offset(btf1, t1->name_off);
fn2 = btf_name_by_offset(btf2, t2->name_off);
if (btf_func_linkage(t1) != BTF_FUNC_GLOBAL) {
bpf_log(log, "%s() is not a global function\n", fn1);
return -EINVAL;
}
if (btf_func_linkage(t2) != BTF_FUNC_GLOBAL) {
bpf_log(log, "%s() is not a global function\n", fn2);
return -EINVAL;
}
t1 = btf_type_by_id(btf1, t1->type);
if (!t1 || !btf_type_is_func_proto(t1))
return -EFAULT;
t2 = btf_type_by_id(btf2, t2->type);
if (!t2 || !btf_type_is_func_proto(t2))
return -EFAULT;
args1 = (const struct btf_param *)(t1 + 1);
nargs1 = btf_type_vlen(t1);
args2 = (const struct btf_param *)(t2 + 1);
nargs2 = btf_type_vlen(t2);
if (nargs1 != nargs2) {
bpf_log(log, "%s() has %d args while %s() has %d args\n",
fn1, nargs1, fn2, nargs2);
return -EINVAL;
}
t1 = btf_type_skip_modifiers(btf1, t1->type, NULL);
t2 = btf_type_skip_modifiers(btf2, t2->type, NULL);
if (t1->info != t2->info) {
bpf_log(log,
"Return type %s of %s() doesn't match type %s of %s()\n",
btf_type_str(t1), fn1,
btf_type_str(t2), fn2);
return -EINVAL;
}
for (i = 0; i < nargs1; i++) {
t1 = btf_type_skip_modifiers(btf1, args1[i].type, NULL);
t2 = btf_type_skip_modifiers(btf2, args2[i].type, NULL);
if (t1->info != t2->info) {
bpf_log(log, "arg%d in %s() is %s while %s() has %s\n",
i, fn1, btf_type_str(t1),
fn2, btf_type_str(t2));
return -EINVAL;
}
if (btf_type_has_size(t1) && t1->size != t2->size) {
bpf_log(log,
"arg%d in %s() has size %d while %s() has %d\n",
i, fn1, t1->size,
fn2, t2->size);
return -EINVAL;
}
/* global functions are validated with scalars and pointers
* to context only. And only global functions can be replaced.
* Hence type check only those types.
*/
if (btf_type_is_int(t1) || btf_type_is_enum(t1))
continue;
if (!btf_type_is_ptr(t1)) {
bpf_log(log,
"arg%d in %s() has unrecognized type\n",
i, fn1);
return -EINVAL;
}
t1 = btf_type_skip_modifiers(btf1, t1->type, NULL);
t2 = btf_type_skip_modifiers(btf2, t2->type, NULL);
if (!btf_type_is_struct(t1)) {
bpf_log(log,
"arg%d in %s() is not a pointer to context\n",
i, fn1);
return -EINVAL;
}
if (!btf_type_is_struct(t2)) {
bpf_log(log,
"arg%d in %s() is not a pointer to context\n",
i, fn2);
return -EINVAL;
}
/* This is an optional check to make program writing easier.
* Compare names of structs and report an error to the user.
* btf_prepare_func_args() already checked that t2 struct
* is a context type. btf_prepare_func_args() will check
* later that t1 struct is a context type as well.
*/
s1 = btf_name_by_offset(btf1, t1->name_off);
s2 = btf_name_by_offset(btf2, t2->name_off);
if (strcmp(s1, s2)) {
bpf_log(log,
"arg%d %s(struct %s *) doesn't match %s(struct %s *)\n",
i, fn1, s1, fn2, s2);
return -EINVAL;
}
}
return 0;
}
/* Compare BTFs of given program with BTF of target program */
int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *prog,
struct btf *btf2, const struct btf_type *t2)
{
struct btf *btf1 = prog->aux->btf;
const struct btf_type *t1;
u32 btf_id = 0;
if (!prog->aux->func_info) {
bpf_log(log, "Program extension requires BTF\n");
return -EINVAL;
}
btf_id = prog->aux->func_info[0].type_id;
if (!btf_id)
return -EFAULT;
t1 = btf_type_by_id(btf1, btf_id);
if (!t1 || !btf_type_is_func(t1))
return -EFAULT;
return btf_check_func_type_match(log, btf1, t1, btf2, t2);
}
static u32 *reg2btf_ids[__BPF_REG_TYPE_MAX] = {
#ifdef CONFIG_NET
[PTR_TO_SOCKET] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK],
[PTR_TO_SOCK_COMMON] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
[PTR_TO_TCP_SOCK] = &btf_sock_ids[BTF_SOCK_TYPE_TCP],
#endif
};
/* Returns true if struct is composed of scalars, 4 levels of nesting allowed */
static bool __btf_type_is_scalar_struct(struct bpf_verifier_log *log,
const struct btf *btf,
const struct btf_type *t, int rec)
{
const struct btf_type *member_type;
const struct btf_member *member;
u32 i;
if (!btf_type_is_struct(t))
return false;
for_each_member(i, t, member) {
const struct btf_array *array;
member_type = btf_type_skip_modifiers(btf, member->type, NULL);
if (btf_type_is_struct(member_type)) {
if (rec >= 3) {
bpf_log(log, "max struct nesting depth exceeded\n");
return false;
}
if (!__btf_type_is_scalar_struct(log, btf, member_type, rec + 1))
return false;
continue;
}
if (btf_type_is_array(member_type)) {
array = btf_type_array(member_type);
if (!array->nelems)
return false;
member_type = btf_type_skip_modifiers(btf, array->type, NULL);
if (!btf_type_is_scalar(member_type))
return false;
continue;
}
if (!btf_type_is_scalar(member_type))
return false;
}
return true;
}
static bool is_kfunc_arg_mem_size(const struct btf *btf,
const struct btf_param *arg,
const struct bpf_reg_state *reg)
{
int len, sfx_len = sizeof("__sz") - 1;
const struct btf_type *t;
const char *param_name;
t = btf_type_skip_modifiers(btf, arg->type, NULL);
if (!btf_type_is_scalar(t) || reg->type != SCALAR_VALUE)
return false;
/* In the future, this can be ported to use BTF tagging */
param_name = btf_name_by_offset(btf, arg->name_off);
if (str_is_empty(param_name))
return false;
len = strlen(param_name);
if (len < sfx_len)
return false;
param_name += len - sfx_len;
if (strncmp(param_name, "__sz", sfx_len))
return false;
return true;
}
static int btf_check_func_arg_match(struct bpf_verifier_env *env,
const struct btf *btf, u32 func_id,
struct bpf_reg_state *regs,
bool ptr_to_mem_ok)
{
struct bpf_verifier_log *log = &env->log;
u32 i, nargs, ref_id, ref_obj_id = 0;
bool is_kfunc = btf_is_kernel(btf);
bool rel = false, kptr_get = false;
const char *func_name, *ref_tname;
const struct btf_type *t, *ref_t;
const struct btf_param *args;
int ref_regno = 0, ret;
t = btf_type_by_id(btf, func_id);
if (!t || !btf_type_is_func(t)) {
/* These checks were already done by the verifier while loading
* struct bpf_func_info or in add_kfunc_call().
*/
bpf_log(log, "BTF of func_id %u doesn't point to KIND_FUNC\n",
func_id);
return -EFAULT;
}
func_name = btf_name_by_offset(btf, t->name_off);
t = btf_type_by_id(btf, t->type);
if (!t || !btf_type_is_func_proto(t)) {
bpf_log(log, "Invalid BTF of func %s\n", func_name);
return -EFAULT;
}
args = (const struct btf_param *)(t + 1);
nargs = btf_type_vlen(t);
if (nargs > MAX_BPF_FUNC_REG_ARGS) {
bpf_log(log, "Function %s has %d > %d args\n", func_name, nargs,
MAX_BPF_FUNC_REG_ARGS);
return -EINVAL;
}
if (is_kfunc) {
/* Only kfunc can be release func */
rel = btf_kfunc_id_set_contains(btf, resolve_prog_type(env->prog),
BTF_KFUNC_TYPE_RELEASE, func_id);
kptr_get = btf_kfunc_id_set_contains(btf, resolve_prog_type(env->prog),
BTF_KFUNC_TYPE_KPTR_ACQUIRE, func_id);
}
/* check that BTF function arguments match actual types that the
* verifier sees.
*/
for (i = 0; i < nargs; i++) {
enum bpf_arg_type arg_type = ARG_DONTCARE;
u32 regno = i + 1;
struct bpf_reg_state *reg = &regs[regno];
t = btf_type_skip_modifiers(btf, args[i].type, NULL);
if (btf_type_is_scalar(t)) {
if (reg->type == SCALAR_VALUE)
continue;
bpf_log(log, "R%d is not a scalar\n", regno);
return -EINVAL;
}
if (!btf_type_is_ptr(t)) {
bpf_log(log, "Unrecognized arg#%d type %s\n",
i, btf_type_str(t));
return -EINVAL;
}
ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id);
ref_tname = btf_name_by_offset(btf, ref_t->name_off);
if (rel && reg->ref_obj_id)
arg_type |= OBJ_RELEASE;
ret = check_func_arg_reg_off(env, reg, regno, arg_type);
if (ret < 0)
return ret;
/* kptr_get is only true for kfunc */
if (i == 0 && kptr_get) {
struct bpf_map_value_off_desc *off_desc;
if (reg->type != PTR_TO_MAP_VALUE) {
bpf_log(log, "arg#0 expected pointer to map value\n");
return -EINVAL;
}
/* check_func_arg_reg_off allows var_off for
* PTR_TO_MAP_VALUE, but we need fixed offset to find
* off_desc.
*/
if (!tnum_is_const(reg->var_off)) {
bpf_log(log, "arg#0 must have constant offset\n");
return -EINVAL;
}
off_desc = bpf_map_kptr_off_contains(reg->map_ptr, reg->off + reg->var_off.value);
if (!off_desc || off_desc->type != BPF_KPTR_REF) {
bpf_log(log, "arg#0 no referenced kptr at map value offset=%llu\n",
reg->off + reg->var_off.value);
return -EINVAL;
}
if (!btf_type_is_ptr(ref_t)) {
bpf_log(log, "arg#0 BTF type must be a double pointer\n");
return -EINVAL;
}
ref_t = btf_type_skip_modifiers(btf, ref_t->type, &ref_id);
ref_tname = btf_name_by_offset(btf, ref_t->name_off);
if (!btf_type_is_struct(ref_t)) {
bpf_log(log, "kernel function %s args#%d pointer type %s %s is not supported\n",
func_name, i, btf_type_str(ref_t), ref_tname);
return -EINVAL;
}
if (!btf_struct_ids_match(log, btf, ref_id, 0, off_desc->kptr.btf,
off_desc->kptr.btf_id, true)) {
bpf_log(log, "kernel function %s args#%d expected pointer to %s %s\n",
func_name, i, btf_type_str(ref_t), ref_tname);
return -EINVAL;
}
/* rest of the arguments can be anything, like normal kfunc */
} else if (btf_get_prog_ctx_type(log, btf, t, env->prog->type, i)) {
/* If function expects ctx type in BTF check that caller
* is passing PTR_TO_CTX.
*/
if (reg->type != PTR_TO_CTX) {
bpf_log(log,
"arg#%d expected pointer to ctx, but got %s\n",
i, btf_type_str(t));
return -EINVAL;
}
} else if (is_kfunc && (reg->type == PTR_TO_BTF_ID ||
(reg2btf_ids[base_type(reg->type)] && !type_flag(reg->type)))) {
const struct btf_type *reg_ref_t;
const struct btf *reg_btf;
const char *reg_ref_tname;
u32 reg_ref_id;
if (!btf_type_is_struct(ref_t)) {
bpf_log(log, "kernel function %s args#%d pointer type %s %s is not supported\n",
func_name, i, btf_type_str(ref_t),
ref_tname);
return -EINVAL;
}
if (reg->type == PTR_TO_BTF_ID) {
reg_btf = reg->btf;
reg_ref_id = reg->btf_id;
/* Ensure only one argument is referenced PTR_TO_BTF_ID */
if (reg->ref_obj_id) {
if (ref_obj_id) {
bpf_log(log, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n",
regno, reg->ref_obj_id, ref_obj_id);
return -EFAULT;
}
ref_regno = regno;
ref_obj_id = reg->ref_obj_id;
}
} else {
reg_btf = btf_vmlinux;
reg_ref_id = *reg2btf_ids[base_type(reg->type)];
}
reg_ref_t = btf_type_skip_modifiers(reg_btf, reg_ref_id,
&reg_ref_id);
reg_ref_tname = btf_name_by_offset(reg_btf,
reg_ref_t->name_off);
if (!btf_struct_ids_match(log, reg_btf, reg_ref_id,
reg->off, btf, ref_id, rel && reg->ref_obj_id)) {
bpf_log(log, "kernel function %s args#%d expected pointer to %s %s but R%d has a pointer to %s %s\n",
func_name, i,
btf_type_str(ref_t), ref_tname,
regno, btf_type_str(reg_ref_t),
reg_ref_tname);
return -EINVAL;
}
} else if (ptr_to_mem_ok) {
const struct btf_type *resolve_ret;
u32 type_size;
if (is_kfunc) {
bool arg_mem_size = i + 1 < nargs && is_kfunc_arg_mem_size(btf, &args[i + 1], &regs[regno + 1]);
/* Permit pointer to mem, but only when argument
* type is pointer to scalar, or struct composed
* (recursively) of scalars.
* When arg_mem_size is true, the pointer can be
* void *.
*/
if (!btf_type_is_scalar(ref_t) &&
!__btf_type_is_scalar_struct(log, btf, ref_t, 0) &&
(arg_mem_size ? !btf_type_is_void(ref_t) : 1)) {
bpf_log(log,
"arg#%d pointer type %s %s must point to %sscalar, or struct with scalar\n",
i, btf_type_str(ref_t), ref_tname, arg_mem_size ? "void, " : "");
return -EINVAL;
}
/* Check for mem, len pair */
if (arg_mem_size) {
if (check_kfunc_mem_size_reg(env, &regs[regno + 1], regno + 1)) {
bpf_log(log, "arg#%d arg#%d memory, len pair leads to invalid memory access\n",
i, i + 1);
return -EINVAL;
}
i++;
continue;
}
}
resolve_ret = btf_resolve_size(btf, ref_t, &type_size);
if (IS_ERR(resolve_ret)) {
bpf_log(log,
"arg#%d reference type('%s %s') size cannot be determined: %ld\n",
i, btf_type_str(ref_t), ref_tname,
PTR_ERR(resolve_ret));
return -EINVAL;
}
if (check_mem_reg(env, reg, regno, type_size))
return -EINVAL;
} else {
bpf_log(log, "reg type unsupported for arg#%d %sfunction %s#%d\n", i,
is_kfunc ? "kernel " : "", func_name, func_id);
return -EINVAL;
}
}
/* Either both are set, or neither */
WARN_ON_ONCE((ref_obj_id && !ref_regno) || (!ref_obj_id && ref_regno));
/* We already made sure ref_obj_id is set only for one argument. We do
* allow (!rel && ref_obj_id), so that passing such referenced
* PTR_TO_BTF_ID to other kfuncs works. Note that rel is only true when
* is_kfunc is true.
*/
if (rel && !ref_obj_id) {
bpf_log(log, "release kernel function %s expects refcounted PTR_TO_BTF_ID\n",
func_name);
return -EINVAL;
}
/* returns argument register number > 0 in case of reference release kfunc */
return rel ? ref_regno : 0;
}
/* Compare BTF of a function with given bpf_reg_state.
* Returns:
* EFAULT - there is a verifier bug. Abort verification.
* EINVAL - there is a type mismatch or BTF is not available.
* 0 - BTF matches with what bpf_reg_state expects.
* Only PTR_TO_CTX and SCALAR_VALUE states are recognized.
*/
int btf_check_subprog_arg_match(struct bpf_verifier_env *env, int subprog,
struct bpf_reg_state *regs)
{
struct bpf_prog *prog = env->prog;
struct btf *btf = prog->aux->btf;
bool is_global;
u32 btf_id;
int err;
if (!prog->aux->func_info)
return -EINVAL;
btf_id = prog->aux->func_info[subprog].type_id;
if (!btf_id)
return -EFAULT;
if (prog->aux->func_info_aux[subprog].unreliable)
return -EINVAL;
is_global = prog->aux->func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL;
err = btf_check_func_arg_match(env, btf, btf_id, regs, is_global);
/* Compiler optimizations can remove arguments from static functions
* or mismatched type can be passed into a global function.
* In such cases mark the function as unreliable from BTF point of view.
*/
if (err)
prog->aux->func_info_aux[subprog].unreliable = true;
return err;
}
int btf_check_kfunc_arg_match(struct bpf_verifier_env *env,
const struct btf *btf, u32 func_id,
struct bpf_reg_state *regs)
{
return btf_check_func_arg_match(env, btf, func_id, regs, true);
}
/* Convert BTF of a function into bpf_reg_state if possible
* Returns:
* EFAULT - there is a verifier bug. Abort verification.
* EINVAL - cannot convert BTF.
* 0 - Successfully converted BTF into bpf_reg_state
* (either PTR_TO_CTX or SCALAR_VALUE).
*/
int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog,
struct bpf_reg_state *regs)
{
struct bpf_verifier_log *log = &env->log;
struct bpf_prog *prog = env->prog;
enum bpf_prog_type prog_type = prog->type;
struct btf *btf = prog->aux->btf;
const struct btf_param *args;
const struct btf_type *t, *ref_t;
u32 i, nargs, btf_id;
const char *tname;
if (!prog->aux->func_info ||
prog->aux->func_info_aux[subprog].linkage != BTF_FUNC_GLOBAL) {
bpf_log(log, "Verifier bug\n");
return -EFAULT;
}
btf_id = prog->aux->func_info[subprog].type_id;
if (!btf_id) {
bpf_log(log, "Global functions need valid BTF\n");
return -EFAULT;
}
t = btf_type_by_id(btf, btf_id);
if (!t || !btf_type_is_func(t)) {
/* These checks were already done by the verifier while loading
* struct bpf_func_info
*/
bpf_log(log, "BTF of func#%d doesn't point to KIND_FUNC\n",
subprog);
return -EFAULT;
}
tname = btf_name_by_offset(btf, t->name_off);
if (log->level & BPF_LOG_LEVEL)
bpf_log(log, "Validating %s() func#%d...\n",
tname, subprog);
if (prog->aux->func_info_aux[subprog].unreliable) {
bpf_log(log, "Verifier bug in function %s()\n", tname);
return -EFAULT;
}
if (prog_type == BPF_PROG_TYPE_EXT)
prog_type = prog->aux->dst_prog->type;
t = btf_type_by_id(btf, t->type);
if (!t || !btf_type_is_func_proto(t)) {
bpf_log(log, "Invalid type of function %s()\n", tname);
return -EFAULT;
}
args = (const struct btf_param *)(t + 1);
nargs = btf_type_vlen(t);
if (nargs > MAX_BPF_FUNC_REG_ARGS) {
bpf_log(log, "Global function %s() with %d > %d args. Buggy compiler.\n",
tname, nargs, MAX_BPF_FUNC_REG_ARGS);
return -EINVAL;
}
/* check that function returns int */
t = btf_type_by_id(btf, t->type);
while (btf_type_is_modifier(t))
t = btf_type_by_id(btf, t->type);
if (!btf_type_is_int(t) && !btf_type_is_enum(t)) {
bpf_log(log,
"Global function %s() doesn't return scalar. Only those are supported.\n",
tname);
return -EINVAL;
}
/* Convert BTF function arguments into verifier types.
* Only PTR_TO_CTX and SCALAR are supported atm.
*/
for (i = 0; i < nargs; i++) {
struct bpf_reg_state *reg = &regs[i + 1];
t = btf_type_by_id(btf, args[i].type);
while (btf_type_is_modifier(t))
t = btf_type_by_id(btf, t->type);
if (btf_type_is_int(t) || btf_type_is_enum(t)) {
reg->type = SCALAR_VALUE;
continue;
}
if (btf_type_is_ptr(t)) {
if (btf_get_prog_ctx_type(log, btf, t, prog_type, i)) {
reg->type = PTR_TO_CTX;
continue;
}
t = btf_type_skip_modifiers(btf, t->type, NULL);
ref_t = btf_resolve_size(btf, t, &reg->mem_size);
if (IS_ERR(ref_t)) {
bpf_log(log,
"arg#%d reference type('%s %s') size cannot be determined: %ld\n",
i, btf_type_str(t), btf_name_by_offset(btf, t->name_off),
PTR_ERR(ref_t));
return -EINVAL;
}
reg->type = PTR_TO_MEM | PTR_MAYBE_NULL;
reg->id = ++env->id_gen;
continue;
}
bpf_log(log, "Arg#%d type %s in %s() is not supported yet.\n",
i, btf_kind_str[BTF_INFO_KIND(t->info)], tname);
return -EINVAL;
}
return 0;
}
static void btf_type_show(const struct btf *btf, u32 type_id, void *obj,
struct btf_show *show)
{
const struct btf_type *t = btf_type_by_id(btf, type_id);
show->btf = btf;
memset(&show->state, 0, sizeof(show->state));
memset(&show->obj, 0, sizeof(show->obj));
btf_type_ops(t)->show(btf, t, type_id, obj, 0, show);
}
static void btf_seq_show(struct btf_show *show, const char *fmt,
va_list args)
{
seq_vprintf((struct seq_file *)show->target, fmt, args);
}
int btf_type_seq_show_flags(const struct btf *btf, u32 type_id,
void *obj, struct seq_file *m, u64 flags)
{
struct btf_show sseq;
sseq.target = m;
sseq.showfn = btf_seq_show;
sseq.flags = flags;
btf_type_show(btf, type_id, obj, &sseq);
return sseq.state.status;
}
void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
struct seq_file *m)
{
(void) btf_type_seq_show_flags(btf, type_id, obj, m,
BTF_SHOW_NONAME | BTF_SHOW_COMPACT |
BTF_SHOW_ZERO | BTF_SHOW_UNSAFE);
}
struct btf_show_snprintf {
struct btf_show show;
int len_left; /* space left in string */
int len; /* length we would have written */
};
static void btf_snprintf_show(struct btf_show *show, const char *fmt,
va_list args)
{
struct btf_show_snprintf *ssnprintf = (struct btf_show_snprintf *)show;
int len;
len = vsnprintf(show->target, ssnprintf->len_left, fmt, args);
if (len < 0) {
ssnprintf->len_left = 0;
ssnprintf->len = len;
} else if (len > ssnprintf->len_left) {
/* no space, drive on to get length we would have written */
ssnprintf->len_left = 0;
ssnprintf->len += len;
} else {
ssnprintf->len_left -= len;
ssnprintf->len += len;
show->target += len;
}
}
int btf_type_snprintf_show(const struct btf *btf, u32 type_id, void *obj,
char *buf, int len, u64 flags)
{
struct btf_show_snprintf ssnprintf;
ssnprintf.show.target = buf;
ssnprintf.show.flags = flags;
ssnprintf.show.showfn = btf_snprintf_show;
ssnprintf.len_left = len;
ssnprintf.len = 0;
btf_type_show(btf, type_id, obj, (struct btf_show *)&ssnprintf);
/* If we encountered an error, return it. */
if (ssnprintf.show.state.status)
return ssnprintf.show.state.status;
/* Otherwise return length we would have written */
return ssnprintf.len;
}
#ifdef CONFIG_PROC_FS
static void bpf_btf_show_fdinfo(struct seq_file *m, struct file *filp)
{
const struct btf *btf = filp->private_data;
seq_printf(m, "btf_id:\t%u\n", btf->id);
}
#endif
static int btf_release(struct inode *inode, struct file *filp)
{
btf_put(filp->private_data);
return 0;
}
const struct file_operations btf_fops = {
#ifdef CONFIG_PROC_FS
.show_fdinfo = bpf_btf_show_fdinfo,
#endif
.release = btf_release,
};
static int __btf_new_fd(struct btf *btf)
{
return anon_inode_getfd("btf", &btf_fops, btf, O_RDONLY | O_CLOEXEC);
}
int btf_new_fd(const union bpf_attr *attr, bpfptr_t uattr)
{
struct btf *btf;
int ret;
btf = btf_parse(make_bpfptr(attr->btf, uattr.is_kernel),
attr->btf_size, attr->btf_log_level,
u64_to_user_ptr(attr->btf_log_buf),
attr->btf_log_size);
if (IS_ERR(btf))
return PTR_ERR(btf);
ret = btf_alloc_id(btf);
if (ret) {
btf_free(btf);
return ret;
}
/*
* The BTF ID is published to the userspace.
* All BTF free must go through call_rcu() from
* now on (i.e. free by calling btf_put()).
*/
ret = __btf_new_fd(btf);
if (ret < 0)
btf_put(btf);
return ret;
}
struct btf *btf_get_by_fd(int fd)
{
struct btf *btf;
struct fd f;
f = fdget(fd);
if (!f.file)
return ERR_PTR(-EBADF);
if (f.file->f_op != &btf_fops) {
fdput(f);
return ERR_PTR(-EINVAL);
}
btf = f.file->private_data;
refcount_inc(&btf->refcnt);
fdput(f);
return btf;
}
int btf_get_info_by_fd(const struct btf *btf,
const union bpf_attr *attr,
union bpf_attr __user *uattr)
{
struct bpf_btf_info __user *uinfo;
struct bpf_btf_info info;
u32 info_copy, btf_copy;
void __user *ubtf;
char __user *uname;
u32 uinfo_len, uname_len, name_len;
int ret = 0;
uinfo = u64_to_user_ptr(attr->info.info);
uinfo_len = attr->info.info_len;
info_copy = min_t(u32, uinfo_len, sizeof(info));
memset(&info, 0, sizeof(info));
if (copy_from_user(&info, uinfo, info_copy))
return -EFAULT;
info.id = btf->id;
ubtf = u64_to_user_ptr(info.btf);
btf_copy = min_t(u32, btf->data_size, info.btf_size);
if (copy_to_user(ubtf, btf->data, btf_copy))
return -EFAULT;
info.btf_size = btf->data_size;
info.kernel_btf = btf->kernel_btf;
uname = u64_to_user_ptr(info.name);
uname_len = info.name_len;
if (!uname ^ !uname_len)
return -EINVAL;
name_len = strlen(btf->name);
info.name_len = name_len;
if (uname) {
if (uname_len >= name_len + 1) {
if (copy_to_user(uname, btf->name, name_len + 1))
return -EFAULT;
} else {
char zero = '\0';
if (copy_to_user(uname, btf->name, uname_len - 1))
return -EFAULT;
if (put_user(zero, uname + uname_len - 1))
return -EFAULT;
/* let user-space know about too short buffer */
ret = -ENOSPC;
}
}
if (copy_to_user(uinfo, &info, info_copy) ||
put_user(info_copy, &uattr->info.info_len))
return -EFAULT;
return ret;
}
int btf_get_fd_by_id(u32 id)
{
struct btf *btf;
int fd;
rcu_read_lock();
btf = idr_find(&btf_idr, id);
if (!btf || !refcount_inc_not_zero(&btf->refcnt))
btf = ERR_PTR(-ENOENT);
rcu_read_unlock();
if (IS_ERR(btf))
return PTR_ERR(btf);
fd = __btf_new_fd(btf);
if (fd < 0)
btf_put(btf);
return fd;
}
u32 btf_obj_id(const struct btf *btf)
{
return btf->id;
}
bool btf_is_kernel(const struct btf *btf)
{
return btf->kernel_btf;
}
bool btf_is_module(const struct btf *btf)
{
return btf->kernel_btf && strcmp(btf->name, "vmlinux") != 0;
}
static int btf_id_cmp_func(const void *a, const void *b)
{
const int *pa = a, *pb = b;
return *pa - *pb;
}
bool btf_id_set_contains(const struct btf_id_set *set, u32 id)
{
return bsearch(&id, set->ids, set->cnt, sizeof(u32), btf_id_cmp_func) != NULL;
}
enum {
BTF_MODULE_F_LIVE = (1 << 0),
};
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
struct btf_module {
struct list_head list;
struct module *module;
struct btf *btf;
struct bin_attribute *sysfs_attr;
int flags;
};
static LIST_HEAD(btf_modules);
static DEFINE_MUTEX(btf_module_mutex);
static ssize_t
btf_module_read(struct file *file, struct kobject *kobj,
struct bin_attribute *bin_attr,
char *buf, loff_t off, size_t len)
{
const struct btf *btf = bin_attr->private;
memcpy(buf, btf->data + off, len);
return len;
}
static void purge_cand_cache(struct btf *btf);
static int btf_module_notify(struct notifier_block *nb, unsigned long op,
void *module)
{
struct btf_module *btf_mod, *tmp;
struct module *mod = module;
struct btf *btf;
int err = 0;
if (mod->btf_data_size == 0 ||
(op != MODULE_STATE_COMING && op != MODULE_STATE_LIVE &&
op != MODULE_STATE_GOING))
goto out;
switch (op) {
case MODULE_STATE_COMING:
btf_mod = kzalloc(sizeof(*btf_mod), GFP_KERNEL);
if (!btf_mod) {
err = -ENOMEM;
goto out;
}
btf = btf_parse_module(mod->name, mod->btf_data, mod->btf_data_size);
if (IS_ERR(btf)) {
pr_warn("failed to validate module [%s] BTF: %ld\n",
mod->name, PTR_ERR(btf));
kfree(btf_mod);
if (!IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH))
err = PTR_ERR(btf);
goto out;
}
err = btf_alloc_id(btf);
if (err) {
btf_free(btf);
kfree(btf_mod);
goto out;
}
purge_cand_cache(NULL);
mutex_lock(&btf_module_mutex);
btf_mod->module = module;
btf_mod->btf = btf;
list_add(&btf_mod->list, &btf_modules);
mutex_unlock(&btf_module_mutex);
if (IS_ENABLED(CONFIG_SYSFS)) {
struct bin_attribute *attr;
attr = kzalloc(sizeof(*attr), GFP_KERNEL);
if (!attr)
goto out;
sysfs_bin_attr_init(attr);
attr->attr.name = btf->name;
attr->attr.mode = 0444;
attr->size = btf->data_size;
attr->private = btf;
attr->read = btf_module_read;
err = sysfs_create_bin_file(btf_kobj, attr);
if (err) {
pr_warn("failed to register module [%s] BTF in sysfs: %d\n",
mod->name, err);
kfree(attr);
err = 0;
goto out;
}
btf_mod->sysfs_attr = attr;
}
break;
case MODULE_STATE_LIVE:
mutex_lock(&btf_module_mutex);
list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
if (btf_mod->module != module)
continue;
btf_mod->flags |= BTF_MODULE_F_LIVE;
break;
}
mutex_unlock(&btf_module_mutex);
break;
case MODULE_STATE_GOING:
mutex_lock(&btf_module_mutex);
list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
if (btf_mod->module != module)
continue;
list_del(&btf_mod->list);
if (btf_mod->sysfs_attr)
sysfs_remove_bin_file(btf_kobj, btf_mod->sysfs_attr);
purge_cand_cache(btf_mod->btf);
btf_put(btf_mod->btf);
kfree(btf_mod->sysfs_attr);
kfree(btf_mod);
break;
}
mutex_unlock(&btf_module_mutex);
break;
}
out:
return notifier_from_errno(err);
}
static struct notifier_block btf_module_nb = {
.notifier_call = btf_module_notify,
};
static int __init btf_module_init(void)
{
register_module_notifier(&btf_module_nb);
return 0;
}
fs_initcall(btf_module_init);
#endif /* CONFIG_DEBUG_INFO_BTF_MODULES */
struct module *btf_try_get_module(const struct btf *btf)
{
struct module *res = NULL;
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
struct btf_module *btf_mod, *tmp;
mutex_lock(&btf_module_mutex);
list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
if (btf_mod->btf != btf)
continue;
/* We must only consider module whose __init routine has
* finished, hence we must check for BTF_MODULE_F_LIVE flag,
* which is set from the notifier callback for
* MODULE_STATE_LIVE.
*/
if ((btf_mod->flags & BTF_MODULE_F_LIVE) && try_module_get(btf_mod->module))
res = btf_mod->module;
break;
}
mutex_unlock(&btf_module_mutex);
#endif
return res;
}
/* Returns struct btf corresponding to the struct module.
* This function can return NULL or ERR_PTR.
*/
static struct btf *btf_get_module_btf(const struct module *module)
{
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
struct btf_module *btf_mod, *tmp;
#endif
struct btf *btf = NULL;
if (!module) {
btf = bpf_get_btf_vmlinux();
if (!IS_ERR_OR_NULL(btf))
btf_get(btf);
return btf;
}
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
mutex_lock(&btf_module_mutex);
list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
if (btf_mod->module != module)
continue;
btf_get(btf_mod->btf);
btf = btf_mod->btf;
break;
}
mutex_unlock(&btf_module_mutex);
#endif
return btf;
}
BPF_CALL_4(bpf_btf_find_by_name_kind, char *, name, int, name_sz, u32, kind, int, flags)
{
struct btf *btf = NULL;
int btf_obj_fd = 0;
long ret;
if (flags)
return -EINVAL;
if (name_sz <= 1 || name[name_sz - 1])
return -EINVAL;
ret = bpf_find_btf_id(name, kind, &btf);
if (ret > 0 && btf_is_module(btf)) {
btf_obj_fd = __btf_new_fd(btf);
if (btf_obj_fd < 0) {
btf_put(btf);
return btf_obj_fd;
}
return ret | (((u64)btf_obj_fd) << 32);
}
if (ret > 0)
btf_put(btf);
return ret;
}
const struct bpf_func_proto bpf_btf_find_by_name_kind_proto = {
.func = bpf_btf_find_by_name_kind,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_MEM | MEM_RDONLY,
.arg2_type = ARG_CONST_SIZE,
.arg3_type = ARG_ANYTHING,
.arg4_type = ARG_ANYTHING,
};
BTF_ID_LIST_GLOBAL(btf_tracing_ids, MAX_BTF_TRACING_TYPE)
#define BTF_TRACING_TYPE(name, type) BTF_ID(struct, type)
BTF_TRACING_TYPE_xxx
#undef BTF_TRACING_TYPE
/* Kernel Function (kfunc) BTF ID set registration API */
static int __btf_populate_kfunc_set(struct btf *btf, enum btf_kfunc_hook hook,
enum btf_kfunc_type type,
struct btf_id_set *add_set, bool vmlinux_set)
{
struct btf_kfunc_set_tab *tab;
struct btf_id_set *set;
u32 set_cnt;
int ret;
if (hook >= BTF_KFUNC_HOOK_MAX || type >= BTF_KFUNC_TYPE_MAX) {
ret = -EINVAL;
goto end;
}
if (!add_set->cnt)
return 0;
tab = btf->kfunc_set_tab;
if (!tab) {
tab = kzalloc(sizeof(*tab), GFP_KERNEL | __GFP_NOWARN);
if (!tab)
return -ENOMEM;
btf->kfunc_set_tab = tab;
}
set = tab->sets[hook][type];
/* Warn when register_btf_kfunc_id_set is called twice for the same hook
* for module sets.
*/
if (WARN_ON_ONCE(set && !vmlinux_set)) {
ret = -EINVAL;
goto end;
}
/* We don't need to allocate, concatenate, and sort module sets, because
* only one is allowed per hook. Hence, we can directly assign the
* pointer and return.
*/
if (!vmlinux_set) {
tab->sets[hook][type] = add_set;
return 0;
}
/* In case of vmlinux sets, there may be more than one set being
* registered per hook. To create a unified set, we allocate a new set
* and concatenate all individual sets being registered. While each set
* is individually sorted, they may become unsorted when concatenated,
* hence re-sorting the final set again is required to make binary
* searching the set using btf_id_set_contains function work.
*/
set_cnt = set ? set->cnt : 0;
if (set_cnt > U32_MAX - add_set->cnt) {
ret = -EOVERFLOW;
goto end;
}
if (set_cnt + add_set->cnt > BTF_KFUNC_SET_MAX_CNT) {
ret = -E2BIG;
goto end;
}
/* Grow set */
set = krealloc(tab->sets[hook][type],
offsetof(struct btf_id_set, ids[set_cnt + add_set->cnt]),
GFP_KERNEL | __GFP_NOWARN);
if (!set) {
ret = -ENOMEM;
goto end;
}
/* For newly allocated set, initialize set->cnt to 0 */
if (!tab->sets[hook][type])
set->cnt = 0;
tab->sets[hook][type] = set;
/* Concatenate the two sets */
memcpy(set->ids + set->cnt, add_set->ids, add_set->cnt * sizeof(set->ids[0]));
set->cnt += add_set->cnt;
sort(set->ids, set->cnt, sizeof(set->ids[0]), btf_id_cmp_func, NULL);
return 0;
end:
btf_free_kfunc_set_tab(btf);
return ret;
}
static int btf_populate_kfunc_set(struct btf *btf, enum btf_kfunc_hook hook,
const struct btf_kfunc_id_set *kset)
{
bool vmlinux_set = !btf_is_module(btf);
int type, ret = 0;
for (type = 0; type < ARRAY_SIZE(kset->sets); type++) {
if (!kset->sets[type])
continue;
ret = __btf_populate_kfunc_set(btf, hook, type, kset->sets[type], vmlinux_set);
if (ret)
break;
}
return ret;
}
static bool __btf_kfunc_id_set_contains(const struct btf *btf,
enum btf_kfunc_hook hook,
enum btf_kfunc_type type,
u32 kfunc_btf_id)
{
struct btf_id_set *set;
if (hook >= BTF_KFUNC_HOOK_MAX || type >= BTF_KFUNC_TYPE_MAX)
return false;
if (!btf->kfunc_set_tab)
return false;
set = btf->kfunc_set_tab->sets[hook][type];
if (!set)
return false;
return btf_id_set_contains(set, kfunc_btf_id);
}
static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type)
{
switch (prog_type) {
case BPF_PROG_TYPE_XDP:
return BTF_KFUNC_HOOK_XDP;
case BPF_PROG_TYPE_SCHED_CLS:
return BTF_KFUNC_HOOK_TC;
case BPF_PROG_TYPE_STRUCT_OPS:
return BTF_KFUNC_HOOK_STRUCT_OPS;
default:
return BTF_KFUNC_HOOK_MAX;
}
}
/* Caution:
* Reference to the module (obtained using btf_try_get_module) corresponding to
* the struct btf *MUST* be held when calling this function from verifier
* context. This is usually true as we stash references in prog's kfunc_btf_tab;
* keeping the reference for the duration of the call provides the necessary
* protection for looking up a well-formed btf->kfunc_set_tab.
*/
bool btf_kfunc_id_set_contains(const struct btf *btf,
enum bpf_prog_type prog_type,
enum btf_kfunc_type type, u32 kfunc_btf_id)
{
enum btf_kfunc_hook hook;
hook = bpf_prog_type_to_kfunc_hook(prog_type);
return __btf_kfunc_id_set_contains(btf, hook, type, kfunc_btf_id);
}
/* This function must be invoked only from initcalls/module init functions */
int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
const struct btf_kfunc_id_set *kset)
{
enum btf_kfunc_hook hook;
struct btf *btf;
int ret;
btf = btf_get_module_btf(kset->owner);
if (!btf) {
if (!kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
pr_err("missing vmlinux BTF, cannot register kfuncs\n");
return -ENOENT;
}
if (kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) {
pr_err("missing module BTF, cannot register kfuncs\n");
return -ENOENT;
}
return 0;
}
if (IS_ERR(btf))
return PTR_ERR(btf);
hook = bpf_prog_type_to_kfunc_hook(prog_type);
ret = btf_populate_kfunc_set(btf, hook, kset);
btf_put(btf);
return ret;
}
EXPORT_SYMBOL_GPL(register_btf_kfunc_id_set);
s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id)
{
struct btf_id_dtor_kfunc_tab *tab = btf->dtor_kfunc_tab;
struct btf_id_dtor_kfunc *dtor;
if (!tab)
return -ENOENT;
/* Even though the size of tab->dtors[0] is > sizeof(u32), we only need
* to compare the first u32 with btf_id, so we can reuse btf_id_cmp_func.
*/
BUILD_BUG_ON(offsetof(struct btf_id_dtor_kfunc, btf_id) != 0);
dtor = bsearch(&btf_id, tab->dtors, tab->cnt, sizeof(tab->dtors[0]), btf_id_cmp_func);
if (!dtor)
return -ENOENT;
return dtor->kfunc_btf_id;
}
static int btf_check_dtor_kfuncs(struct btf *btf, const struct btf_id_dtor_kfunc *dtors, u32 cnt)
{
const struct btf_type *dtor_func, *dtor_func_proto, *t;
const struct btf_param *args;
s32 dtor_btf_id;
u32 nr_args, i;
for (i = 0; i < cnt; i++) {
dtor_btf_id = dtors[i].kfunc_btf_id;
dtor_func = btf_type_by_id(btf, dtor_btf_id);
if (!dtor_func || !btf_type_is_func(dtor_func))
return -EINVAL;
dtor_func_proto = btf_type_by_id(btf, dtor_func->type);
if (!dtor_func_proto || !btf_type_is_func_proto(dtor_func_proto))
return -EINVAL;
/* Make sure the prototype of the destructor kfunc is 'void func(type *)' */
t = btf_type_by_id(btf, dtor_func_proto->type);
if (!t || !btf_type_is_void(t))
return -EINVAL;
nr_args = btf_type_vlen(dtor_func_proto);
if (nr_args != 1)
return -EINVAL;
args = btf_params(dtor_func_proto);
t = btf_type_by_id(btf, args[0].type);
/* Allow any pointer type, as width on targets Linux supports
* will be same for all pointer types (i.e. sizeof(void *))
*/
if (!t || !btf_type_is_ptr(t))
return -EINVAL;
}
return 0;
}
/* This function must be invoked only from initcalls/module init functions */
int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt,
struct module *owner)
{
struct btf_id_dtor_kfunc_tab *tab;
struct btf *btf;
u32 tab_cnt;
int ret;
btf = btf_get_module_btf(owner);
if (!btf) {
if (!owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
pr_err("missing vmlinux BTF, cannot register dtor kfuncs\n");
return -ENOENT;
}
if (owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) {
pr_err("missing module BTF, cannot register dtor kfuncs\n");
return -ENOENT;
}
return 0;
}
if (IS_ERR(btf))
return PTR_ERR(btf);
if (add_cnt >= BTF_DTOR_KFUNC_MAX_CNT) {
pr_err("cannot register more than %d kfunc destructors\n", BTF_DTOR_KFUNC_MAX_CNT);
ret = -E2BIG;
goto end;
}
/* Ensure that the prototype of dtor kfuncs being registered is sane */
ret = btf_check_dtor_kfuncs(btf, dtors, add_cnt);
if (ret < 0)
goto end;
tab = btf->dtor_kfunc_tab;
/* Only one call allowed for modules */
if (WARN_ON_ONCE(tab && btf_is_module(btf))) {
ret = -EINVAL;
goto end;
}
tab_cnt = tab ? tab->cnt : 0;
if (tab_cnt > U32_MAX - add_cnt) {
ret = -EOVERFLOW;
goto end;
}
if (tab_cnt + add_cnt >= BTF_DTOR_KFUNC_MAX_CNT) {
pr_err("cannot register more than %d kfunc destructors\n", BTF_DTOR_KFUNC_MAX_CNT);
ret = -E2BIG;
goto end;
}
tab = krealloc(btf->dtor_kfunc_tab,
offsetof(struct btf_id_dtor_kfunc_tab, dtors[tab_cnt + add_cnt]),
GFP_KERNEL | __GFP_NOWARN);
if (!tab) {
ret = -ENOMEM;
goto end;
}
if (!btf->dtor_kfunc_tab)
tab->cnt = 0;
btf->dtor_kfunc_tab = tab;
memcpy(tab->dtors + tab->cnt, dtors, add_cnt * sizeof(tab->dtors[0]));
tab->cnt += add_cnt;
sort(tab->dtors, tab->cnt, sizeof(tab->dtors[0]), btf_id_cmp_func, NULL);
return 0;
end:
btf_free_dtor_kfunc_tab(btf);
btf_put(btf);
return ret;
}
EXPORT_SYMBOL_GPL(register_btf_id_dtor_kfuncs);
#define MAX_TYPES_ARE_COMPAT_DEPTH 2
static
int __bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
const struct btf *targ_btf, __u32 targ_id,
int level)
{
const struct btf_type *local_type, *targ_type;
int depth = 32; /* max recursion depth */
/* caller made sure that names match (ignoring flavor suffix) */
local_type = btf_type_by_id(local_btf, local_id);
targ_type = btf_type_by_id(targ_btf, targ_id);
if (btf_kind(local_type) != btf_kind(targ_type))
return 0;
recur:
depth--;
if (depth < 0)
return -EINVAL;
local_type = btf_type_skip_modifiers(local_btf, local_id, &local_id);
targ_type = btf_type_skip_modifiers(targ_btf, targ_id, &targ_id);
if (!local_type || !targ_type)
return -EINVAL;
if (btf_kind(local_type) != btf_kind(targ_type))
return 0;
switch (btf_kind(local_type)) {
case BTF_KIND_UNKN:
case BTF_KIND_STRUCT:
case BTF_KIND_UNION:
case BTF_KIND_ENUM:
case BTF_KIND_FWD:
return 1;
case BTF_KIND_INT:
/* just reject deprecated bitfield-like integers; all other
* integers are by default compatible between each other
*/
return btf_int_offset(local_type) == 0 && btf_int_offset(targ_type) == 0;
case BTF_KIND_PTR:
local_id = local_type->type;
targ_id = targ_type->type;
goto recur;
case BTF_KIND_ARRAY:
local_id = btf_array(local_type)->type;
targ_id = btf_array(targ_type)->type;
goto recur;
case BTF_KIND_FUNC_PROTO: {
struct btf_param *local_p = btf_params(local_type);
struct btf_param *targ_p = btf_params(targ_type);
__u16 local_vlen = btf_vlen(local_type);
__u16 targ_vlen = btf_vlen(targ_type);
int i, err;
if (local_vlen != targ_vlen)
return 0;
for (i = 0; i < local_vlen; i++, local_p++, targ_p++) {
if (level <= 0)
return -EINVAL;
btf_type_skip_modifiers(local_btf, local_p->type, &local_id);
btf_type_skip_modifiers(targ_btf, targ_p->type, &targ_id);
err = __bpf_core_types_are_compat(local_btf, local_id,
targ_btf, targ_id,
level - 1);
if (err <= 0)
return err;
}
/* tail recurse for return type check */
btf_type_skip_modifiers(local_btf, local_type->type, &local_id);
btf_type_skip_modifiers(targ_btf, targ_type->type, &targ_id);
goto recur;
}
default:
return 0;
}
}
/* Check local and target types for compatibility. This check is used for
* type-based CO-RE relocations and follow slightly different rules than
* field-based relocations. This function assumes that root types were already
* checked for name match. Beyond that initial root-level name check, names
* are completely ignored. Compatibility rules are as follows:
* - any two STRUCTs/UNIONs/FWDs/ENUMs/INTs are considered compatible, but
* kind should match for local and target types (i.e., STRUCT is not
* compatible with UNION);
* - for ENUMs, the size is ignored;
* - for INT, size and signedness are ignored;
* - for ARRAY, dimensionality is ignored, element types are checked for
* compatibility recursively;
* - CONST/VOLATILE/RESTRICT modifiers are ignored;
* - TYPEDEFs/PTRs are compatible if types they pointing to are compatible;
* - FUNC_PROTOs are compatible if they have compatible signature: same
* number of input args and compatible return and argument types.
* These rules are not set in stone and probably will be adjusted as we get
* more experience with using BPF CO-RE relocations.
*/
int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
const struct btf *targ_btf, __u32 targ_id)
{
return __bpf_core_types_are_compat(local_btf, local_id,
targ_btf, targ_id,
MAX_TYPES_ARE_COMPAT_DEPTH);
}
static bool bpf_core_is_flavor_sep(const char *s)
{
/* check X___Y name pattern, where X and Y are not underscores */
return s[0] != '_' && /* X */
s[1] == '_' && s[2] == '_' && s[3] == '_' && /* ___ */
s[4] != '_'; /* Y */
}
size_t bpf_core_essential_name_len(const char *name)
{
size_t n = strlen(name);
int i;
for (i = n - 5; i >= 0; i--) {
if (bpf_core_is_flavor_sep(name + i))
return i + 1;
}
return n;
}
struct bpf_cand_cache {
const char *name;
u32 name_len;
u16 kind;
u16 cnt;
struct {
const struct btf *btf;
u32 id;
} cands[];
};
static void bpf_free_cands(struct bpf_cand_cache *cands)
{
if (!cands->cnt)
/* empty candidate array was allocated on stack */
return;
kfree(cands);
}
static void bpf_free_cands_from_cache(struct bpf_cand_cache *cands)
{
kfree(cands->name);
kfree(cands);
}
#define VMLINUX_CAND_CACHE_SIZE 31
static struct bpf_cand_cache *vmlinux_cand_cache[VMLINUX_CAND_CACHE_SIZE];
#define MODULE_CAND_CACHE_SIZE 31
static struct bpf_cand_cache *module_cand_cache[MODULE_CAND_CACHE_SIZE];
static DEFINE_MUTEX(cand_cache_mutex);
static void __print_cand_cache(struct bpf_verifier_log *log,
struct bpf_cand_cache **cache,
int cache_size)
{
struct bpf_cand_cache *cc;
int i, j;
for (i = 0; i < cache_size; i++) {
cc = cache[i];
if (!cc)
continue;
bpf_log(log, "[%d]%s(", i, cc->name);
for (j = 0; j < cc->cnt; j++) {
bpf_log(log, "%d", cc->cands[j].id);
if (j < cc->cnt - 1)
bpf_log(log, " ");
}
bpf_log(log, "), ");
}
}
static void print_cand_cache(struct bpf_verifier_log *log)
{
mutex_lock(&cand_cache_mutex);
bpf_log(log, "vmlinux_cand_cache:");
__print_cand_cache(log, vmlinux_cand_cache, VMLINUX_CAND_CACHE_SIZE);
bpf_log(log, "\nmodule_cand_cache:");
__print_cand_cache(log, module_cand_cache, MODULE_CAND_CACHE_SIZE);
bpf_log(log, "\n");
mutex_unlock(&cand_cache_mutex);
}
static u32 hash_cands(struct bpf_cand_cache *cands)
{
return jhash(cands->name, cands->name_len, 0);
}
static struct bpf_cand_cache *check_cand_cache(struct bpf_cand_cache *cands,
struct bpf_cand_cache **cache,
int cache_size)
{
struct bpf_cand_cache *cc = cache[hash_cands(cands) % cache_size];
if (cc && cc->name_len == cands->name_len &&
!strncmp(cc->name, cands->name, cands->name_len))
return cc;
return NULL;
}
static size_t sizeof_cands(int cnt)
{
return offsetof(struct bpf_cand_cache, cands[cnt]);
}
static struct bpf_cand_cache *populate_cand_cache(struct bpf_cand_cache *cands,
struct bpf_cand_cache **cache,
int cache_size)
{
struct bpf_cand_cache **cc = &cache[hash_cands(cands) % cache_size], *new_cands;
if (*cc) {
bpf_free_cands_from_cache(*cc);
*cc = NULL;
}
new_cands = kmemdup(cands, sizeof_cands(cands->cnt), GFP_KERNEL);
if (!new_cands) {
bpf_free_cands(cands);
return ERR_PTR(-ENOMEM);
}
/* strdup the name, since it will stay in cache.
* the cands->name points to strings in prog's BTF and the prog can be unloaded.
*/
new_cands->name = kmemdup_nul(cands->name, cands->name_len, GFP_KERNEL);
bpf_free_cands(cands);
if (!new_cands->name) {
kfree(new_cands);
return ERR_PTR(-ENOMEM);
}
*cc = new_cands;
return new_cands;
}
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
static void __purge_cand_cache(struct btf *btf, struct bpf_cand_cache **cache,
int cache_size)
{
struct bpf_cand_cache *cc;
int i, j;
for (i = 0; i < cache_size; i++) {
cc = cache[i];
if (!cc)
continue;
if (!btf) {
/* when new module is loaded purge all of module_cand_cache,
* since new module might have candidates with the name
* that matches cached cands.
*/
bpf_free_cands_from_cache(cc);
cache[i] = NULL;
continue;
}
/* when module is unloaded purge cache entries
* that match module's btf
*/
for (j = 0; j < cc->cnt; j++)
if (cc->cands[j].btf == btf) {
bpf_free_cands_from_cache(cc);
cache[i] = NULL;
break;
}
}
}
static void purge_cand_cache(struct btf *btf)
{
mutex_lock(&cand_cache_mutex);
__purge_cand_cache(btf, module_cand_cache, MODULE_CAND_CACHE_SIZE);
mutex_unlock(&cand_cache_mutex);
}
#endif
static struct bpf_cand_cache *
bpf_core_add_cands(struct bpf_cand_cache *cands, const struct btf *targ_btf,
int targ_start_id)
{
struct bpf_cand_cache *new_cands;
const struct btf_type *t;
const char *targ_name;
size_t targ_essent_len;
int n, i;
n = btf_nr_types(targ_btf);
for (i = targ_start_id; i < n; i++) {
t = btf_type_by_id(targ_btf, i);
if (btf_kind(t) != cands->kind)
continue;
targ_name = btf_name_by_offset(targ_btf, t->name_off);
if (!targ_name)
continue;
/* the resched point is before strncmp to make sure that search
* for non-existing name will have a chance to schedule().
*/
cond_resched();
if (strncmp(cands->name, targ_name, cands->name_len) != 0)
continue;
targ_essent_len = bpf_core_essential_name_len(targ_name);
if (targ_essent_len != cands->name_len)
continue;
/* most of the time there is only one candidate for a given kind+name pair */
new_cands = kmalloc(sizeof_cands(cands->cnt + 1), GFP_KERNEL);
if (!new_cands) {
bpf_free_cands(cands);
return ERR_PTR(-ENOMEM);
}
memcpy(new_cands, cands, sizeof_cands(cands->cnt));
bpf_free_cands(cands);
cands = new_cands;
cands->cands[cands->cnt].btf = targ_btf;
cands->cands[cands->cnt].id = i;
cands->cnt++;
}
return cands;
}
static struct bpf_cand_cache *
bpf_core_find_cands(struct bpf_core_ctx *ctx, u32 local_type_id)
{
struct bpf_cand_cache *cands, *cc, local_cand = {};
const struct btf *local_btf = ctx->btf;
const struct btf_type *local_type;
const struct btf *main_btf;
size_t local_essent_len;
struct btf *mod_btf;
const char *name;
int id;
main_btf = bpf_get_btf_vmlinux();
if (IS_ERR(main_btf))
return ERR_CAST(main_btf);
if (!main_btf)
return ERR_PTR(-EINVAL);
local_type = btf_type_by_id(local_btf, local_type_id);
if (!local_type)
return ERR_PTR(-EINVAL);
name = btf_name_by_offset(local_btf, local_type->name_off);
if (str_is_empty(name))
return ERR_PTR(-EINVAL);
local_essent_len = bpf_core_essential_name_len(name);
cands = &local_cand;
cands->name = name;
cands->kind = btf_kind(local_type);
cands->name_len = local_essent_len;
cc = check_cand_cache(cands, vmlinux_cand_cache, VMLINUX_CAND_CACHE_SIZE);
/* cands is a pointer to stack here */
if (cc) {
if (cc->cnt)
return cc;
goto check_modules;
}
/* Attempt to find target candidates in vmlinux BTF first */
cands = bpf_core_add_cands(cands, main_btf, 1);
if (IS_ERR(cands))
return ERR_CAST(cands);
/* cands is a pointer to kmalloced memory here if cands->cnt > 0 */
/* populate cache even when cands->cnt == 0 */
cc = populate_cand_cache(cands, vmlinux_cand_cache, VMLINUX_CAND_CACHE_SIZE);
if (IS_ERR(cc))
return ERR_CAST(cc);
/* if vmlinux BTF has any candidate, don't go for module BTFs */
if (cc->cnt)
return cc;
check_modules:
/* cands is a pointer to stack here and cands->cnt == 0 */
cc = check_cand_cache(cands, module_cand_cache, MODULE_CAND_CACHE_SIZE);
if (cc)
/* if cache has it return it even if cc->cnt == 0 */
return cc;
/* If candidate is not found in vmlinux's BTF then search in module's BTFs */
spin_lock_bh(&btf_idr_lock);
idr_for_each_entry(&btf_idr, mod_btf, id) {
if (!btf_is_module(mod_btf))
continue;
/* linear search could be slow hence unlock/lock
* the IDR to avoiding holding it for too long
*/
btf_get(mod_btf);
spin_unlock_bh(&btf_idr_lock);
cands = bpf_core_add_cands(cands, mod_btf, btf_nr_types(main_btf));
if (IS_ERR(cands)) {
btf_put(mod_btf);
return ERR_CAST(cands);
}
spin_lock_bh(&btf_idr_lock);
btf_put(mod_btf);
}
spin_unlock_bh(&btf_idr_lock);
/* cands is a pointer to kmalloced memory here if cands->cnt > 0
* or pointer to stack if cands->cnd == 0.
* Copy it into the cache even when cands->cnt == 0 and
* return the result.
*/
return populate_cand_cache(cands, module_cand_cache, MODULE_CAND_CACHE_SIZE);
}
int bpf_core_apply(struct bpf_core_ctx *ctx, const struct bpf_core_relo *relo,
int relo_idx, void *insn)
{
bool need_cands = relo->kind != BPF_CORE_TYPE_ID_LOCAL;
struct bpf_core_cand_list cands = {};
struct bpf_core_relo_res targ_res;
struct bpf_core_spec *specs;
int err;
/* ~4k of temp memory necessary to convert LLVM spec like "0:1:0:5"
* into arrays of btf_ids of struct fields and array indices.
*/
specs = kcalloc(3, sizeof(*specs), GFP_KERNEL);
if (!specs)
return -ENOMEM;
if (need_cands) {
struct bpf_cand_cache *cc;
int i;
mutex_lock(&cand_cache_mutex);
cc = bpf_core_find_cands(ctx, relo->type_id);
if (IS_ERR(cc)) {
bpf_log(ctx->log, "target candidate search failed for %d\n",
relo->type_id);
err = PTR_ERR(cc);
goto out;
}
if (cc->cnt) {
cands.cands = kcalloc(cc->cnt, sizeof(*cands.cands), GFP_KERNEL);
if (!cands.cands) {
err = -ENOMEM;
goto out;
}
}
for (i = 0; i < cc->cnt; i++) {
bpf_log(ctx->log,
"CO-RE relocating %s %s: found target candidate [%d]\n",
btf_kind_str[cc->kind], cc->name, cc->cands[i].id);
cands.cands[i].btf = cc->cands[i].btf;
cands.cands[i].id = cc->cands[i].id;
}
cands.len = cc->cnt;
/* cand_cache_mutex needs to span the cache lookup and
* copy of btf pointer into bpf_core_cand_list,
* since module can be unloaded while bpf_core_calc_relo_insn
* is working with module's btf.
*/
}
err = bpf_core_calc_relo_insn((void *)ctx->log, relo, relo_idx, ctx->btf, &cands, specs,
&targ_res);
if (err)
goto out;
err = bpf_core_patch_insn((void *)ctx->log, insn, relo->insn_off / 8, relo, relo_idx,
&targ_res);
out:
kfree(specs);
if (need_cands) {
kfree(cands.cands);
mutex_unlock(&cand_cache_mutex);
if (ctx->log->level & BPF_LOG_LEVEL2)
print_cand_cache(ctx->log);
}
return err;
}
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