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bpf: Add support for BPF_OBJ_GET_INFO_BY_FD for bpf_link

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Add ability to fetch bpf_link details through BPF_OBJ_GET_INFO_BY_FD command.
Also enhance show_fdinfo to potentially include bpf_link type-specific
information (similarly to obj_info).

Also introduce enum bpf_link_type stored in bpf_link itself and expose it in
UAPI. bpf_link_tracing also now will store and return bpf_attach_type.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200429001614.1544-5-andriin@fb.com
This commit is contained in:
Andrii Nakryiko 2020-04-28 17:16:08 -07:00 committed by Alexei Starovoitov
parent 2d602c8cf4
commit f2e10bff16
9 changed files with 253 additions and 24 deletions
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2
include/linux/bpf-cgroup.h
View File

@ -57,8 +57,6 @@ struct bpf_cgroup_link {
enum bpf_attach_type type;
};
extern const struct bpf_link_ops bpf_cgroup_link_lops;
struct bpf_prog_list {
struct list_head node;
struct bpf_prog *prog;

8
include/linux/bpf.h
View File

@ -1026,9 +1026,11 @@ extern const struct file_operations bpf_prog_fops;
extern const struct bpf_verifier_ops _name ## _verifier_ops;
#define BPF_MAP_TYPE(_id, _ops) \
extern const struct bpf_map_ops _ops;
#define BPF_LINK_TYPE(_id, _name)
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
#undef BPF_MAP_TYPE
#undef BPF_LINK_TYPE
extern const struct bpf_prog_ops bpf_offload_prog_ops;
extern const struct bpf_verifier_ops tc_cls_act_analyzer_ops;
@ -1086,6 +1088,7 @@ int bpf_prog_new_fd(struct bpf_prog *prog);
struct bpf_link {
atomic64_t refcnt;
u32 id;
enum bpf_link_type type;
const struct bpf_link_ops *ops;
struct bpf_prog *prog;
struct work_struct work;
@ -1103,9 +1106,12 @@ struct bpf_link_ops {
void (*dealloc)(struct bpf_link *link);
int (*update_prog)(struct bpf_link *link, struct bpf_prog *new_prog,
struct bpf_prog *old_prog);
void (*show_fdinfo)(const struct bpf_link *link, struct seq_file *seq);
int (*fill_link_info)(const struct bpf_link *link,
struct bpf_link_info *info);
};
void bpf_link_init(struct bpf_link *link,
void bpf_link_init(struct bpf_link *link, enum bpf_link_type type,
const struct bpf_link_ops *ops, struct bpf_prog *prog);
int bpf_link_prime(struct bpf_link *link, struct bpf_link_primer *primer);
int bpf_link_settle(struct bpf_link_primer *primer);

6
include/linux/bpf_types.h
View File

@ -118,3 +118,9 @@ BPF_MAP_TYPE(BPF_MAP_TYPE_STACK, stack_map_ops)
#if defined(CONFIG_BPF_JIT)
BPF_MAP_TYPE(BPF_MAP_TYPE_STRUCT_OPS, bpf_struct_ops_map_ops)
#endif
BPF_LINK_TYPE(BPF_LINK_TYPE_RAW_TRACEPOINT, raw_tracepoint)
BPF_LINK_TYPE(BPF_LINK_TYPE_TRACING, tracing)
#ifdef CONFIG_CGROUP_BPF
BPF_LINK_TYPE(BPF_LINK_TYPE_CGROUP, cgroup)
#endif

28
include/uapi/linux/bpf.h
View File

@ -222,6 +222,15 @@ enum bpf_attach_type {
#define MAX_BPF_ATTACH_TYPE __MAX_BPF_ATTACH_TYPE
enum bpf_link_type {
BPF_LINK_TYPE_UNSPEC = 0,
BPF_LINK_TYPE_RAW_TRACEPOINT = 1,
BPF_LINK_TYPE_TRACING = 2,
BPF_LINK_TYPE_CGROUP = 3,
MAX_BPF_LINK_TYPE,
};
/* cgroup-bpf attach flags used in BPF_PROG_ATTACH command
*
* NONE(default): No further bpf programs allowed in the subtree.
@ -3612,6 +3621,25 @@ struct bpf_btf_info {
__u32 id;
} __attribute__((aligned(8)));
struct bpf_link_info {
__u32 type;
__u32 id;
__u32 prog_id;
union {
struct {
__aligned_u64 tp_name; /* in/out: tp_name buffer ptr */
__u32 tp_name_len; /* in/out: tp_name buffer len */
} raw_tracepoint;
struct {
__u32 attach_type;
} tracing;
struct {
__u64 cgroup_id;
__u32 attach_type;
} cgroup;
};
} __attribute__((aligned(8)));
/* User bpf_sock_addr struct to access socket fields and sockaddr struct passed
* by user and intended to be used by socket (e.g. to bind to, depends on
* attach attach type).

2
kernel/bpf/btf.c
View File

@ -3482,6 +3482,7 @@ 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) \
@ -3508,6 +3509,7 @@ static u8 bpf_ctx_convert_map[] = {
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, struct btf *btf,

43
kernel/bpf/cgroup.c
View File

@ -833,10 +833,48 @@ static void bpf_cgroup_link_dealloc(struct bpf_link *link)
kfree(cg_link);
}
const struct bpf_link_ops bpf_cgroup_link_lops = {
static void bpf_cgroup_link_show_fdinfo(const struct bpf_link *link,
struct seq_file *seq)
{
struct bpf_cgroup_link *cg_link =
container_of(link, struct bpf_cgroup_link, link);
u64 cg_id = 0;
mutex_lock(&cgroup_mutex);
if (cg_link->cgroup)
cg_id = cgroup_id(cg_link->cgroup);
mutex_unlock(&cgroup_mutex);
seq_printf(seq,
"cgroup_id:\t%llu\n"
"attach_type:\t%d\n",
cg_id,
cg_link->type);
}
static int bpf_cgroup_link_fill_link_info(const struct bpf_link *link,
struct bpf_link_info *info)
{
struct bpf_cgroup_link *cg_link =
container_of(link, struct bpf_cgroup_link, link);
u64 cg_id = 0;
mutex_lock(&cgroup_mutex);
if (cg_link->cgroup)
cg_id = cgroup_id(cg_link->cgroup);
mutex_unlock(&cgroup_mutex);
info->cgroup.cgroup_id = cg_id;
info->cgroup.attach_type = cg_link->type;
return 0;
}
static const struct bpf_link_ops bpf_cgroup_link_lops = {
.release = bpf_cgroup_link_release,
.dealloc = bpf_cgroup_link_dealloc,
.update_prog = cgroup_bpf_replace,
.show_fdinfo = bpf_cgroup_link_show_fdinfo,
.fill_link_info = bpf_cgroup_link_fill_link_info,
};
int cgroup_bpf_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
@ -858,7 +896,8 @@ int cgroup_bpf_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
err = -ENOMEM;
goto out_put_cgroup;
}
bpf_link_init(&link->link, &bpf_cgroup_link_lops, prog);
bpf_link_init(&link->link, BPF_LINK_TYPE_CGROUP, &bpf_cgroup_link_lops,
prog);
link->cgroup = cgrp;
link->type = attr->link_create.attach_type;

155
kernel/bpf/syscall.c
View File

@ -51,9 +51,11 @@ static const struct bpf_map_ops * const bpf_map_types[] = {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type)
#define BPF_MAP_TYPE(_id, _ops) \
[_id] = &_ops,
#define BPF_LINK_TYPE(_id, _name)
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
#undef BPF_MAP_TYPE
#undef BPF_LINK_TYPE
};
/*
@ -1548,9 +1550,11 @@ static const struct bpf_prog_ops * const bpf_prog_types[] = {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
[_id] = & _name ## _prog_ops,
#define BPF_MAP_TYPE(_id, _ops)
#define BPF_LINK_TYPE(_id, _name)
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
#undef BPF_MAP_TYPE
#undef BPF_LINK_TYPE
};
static int find_prog_type(enum bpf_prog_type type, struct bpf_prog *prog)
@ -2183,10 +2187,11 @@ static int bpf_obj_get(const union bpf_attr *attr)
attr->file_flags);
}
void bpf_link_init(struct bpf_link *link,
void bpf_link_init(struct bpf_link *link, enum bpf_link_type type,
const struct bpf_link_ops *ops, struct bpf_prog *prog)
{
atomic64_set(&link->refcnt, 1);
link->type = type;
link->id = 0;
link->ops = ops;
link->prog = prog;
@ -2266,27 +2271,23 @@ static int bpf_link_release(struct inode *inode, struct file *filp)
return 0;
}
#ifdef CONFIG_PROC_FS
static const struct bpf_link_ops bpf_raw_tp_lops;
static const struct bpf_link_ops bpf_tracing_link_lops;
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type)
#define BPF_MAP_TYPE(_id, _ops)
#define BPF_LINK_TYPE(_id, _name) [_id] = #_name,
static const char *bpf_link_type_strs[] = {
[BPF_LINK_TYPE_UNSPEC] = "<invalid>",
#include <linux/bpf_types.h>
};
#undef BPF_PROG_TYPE
#undef BPF_MAP_TYPE
#undef BPF_LINK_TYPE
#ifdef CONFIG_PROC_FS
static void bpf_link_show_fdinfo(struct seq_file *m, struct file *filp)
{
const struct bpf_link *link = filp->private_data;
const struct bpf_prog *prog = link->prog;
char prog_tag[sizeof(prog->tag) * 2 + 1] = { };
const char *link_type;
if (link->ops == &bpf_raw_tp_lops)
link_type = "raw_tracepoint";
else if (link->ops == &bpf_tracing_link_lops)
link_type = "tracing";
#ifdef CONFIG_CGROUP_BPF
else if (link->ops == &bpf_cgroup_link_lops)
link_type = "cgroup";
#endif
else
link_type = "unknown";
bin2hex(prog_tag, prog->tag, sizeof(prog->tag));
seq_printf(m,
@ -2294,10 +2295,12 @@ static void bpf_link_show_fdinfo(struct seq_file *m, struct file *filp)
"link_id:\t%u\n"
"prog_tag:\t%s\n"
"prog_id:\t%u\n",
link_type,
bpf_link_type_strs[link->type],
link->id,
prog_tag,
prog->aux->id);
if (link->ops->show_fdinfo)
link->ops->show_fdinfo(link, m);
}
#endif
@ -2403,6 +2406,7 @@ struct bpf_link *bpf_link_get_from_fd(u32 ufd)
struct bpf_tracing_link {
struct bpf_link link;
enum bpf_attach_type attach_type;
};
static void bpf_tracing_link_release(struct bpf_link *link)
@ -2418,9 +2422,33 @@ static void bpf_tracing_link_dealloc(struct bpf_link *link)
kfree(tr_link);
}
static void bpf_tracing_link_show_fdinfo(const struct bpf_link *link,
struct seq_file *seq)
{
struct bpf_tracing_link *tr_link =
container_of(link, struct bpf_tracing_link, link);
seq_printf(seq,
"attach_type:\t%d\n",
tr_link->attach_type);
}
static int bpf_tracing_link_fill_link_info(const struct bpf_link *link,
struct bpf_link_info *info)
{
struct bpf_tracing_link *tr_link =
container_of(link, struct bpf_tracing_link, link);
info->tracing.attach_type = tr_link->attach_type;
return 0;
}
static const struct bpf_link_ops bpf_tracing_link_lops = {
.release = bpf_tracing_link_release,
.dealloc = bpf_tracing_link_dealloc,
.show_fdinfo = bpf_tracing_link_show_fdinfo,
.fill_link_info = bpf_tracing_link_fill_link_info,
};
static int bpf_tracing_prog_attach(struct bpf_prog *prog)
@ -2460,7 +2488,9 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog)
err = -ENOMEM;
goto out_put_prog;
}
bpf_link_init(&link->link, &bpf_tracing_link_lops, prog);
bpf_link_init(&link->link, BPF_LINK_TYPE_TRACING,
&bpf_tracing_link_lops, prog);
link->attach_type = prog->expected_attach_type;
err = bpf_link_prime(&link->link, &link_primer);
if (err) {
@ -2502,9 +2532,56 @@ static void bpf_raw_tp_link_dealloc(struct bpf_link *link)
kfree(raw_tp);
}
static void bpf_raw_tp_link_show_fdinfo(const struct bpf_link *link,
struct seq_file *seq)
{
struct bpf_raw_tp_link *raw_tp_link =
container_of(link, struct bpf_raw_tp_link, link);
seq_printf(seq,
"tp_name:\t%s\n",
raw_tp_link->btp->tp->name);
}
static int bpf_raw_tp_link_fill_link_info(const struct bpf_link *link,
struct bpf_link_info *info)
{
struct bpf_raw_tp_link *raw_tp_link =
container_of(link, struct bpf_raw_tp_link, link);
char __user *ubuf = u64_to_user_ptr(info->raw_tracepoint.tp_name);
const char *tp_name = raw_tp_link->btp->tp->name;
u32 ulen = info->raw_tracepoint.tp_name_len;
size_t tp_len = strlen(tp_name);
if (ulen && !ubuf)
return -EINVAL;
info->raw_tracepoint.tp_name_len = tp_len + 1;
if (!ubuf)
return 0;
if (ulen >= tp_len + 1) {
if (copy_to_user(ubuf, tp_name, tp_len + 1))
return -EFAULT;
} else {
char zero = '\0';
if (copy_to_user(ubuf, tp_name, ulen - 1))
return -EFAULT;
if (put_user(zero, ubuf + ulen - 1))
return -EFAULT;
return -ENOSPC;
}
return 0;
}
static const struct bpf_link_ops bpf_raw_tp_link_lops = {
.release = bpf_raw_tp_link_release,
.dealloc = bpf_raw_tp_link_dealloc,
.show_fdinfo = bpf_raw_tp_link_show_fdinfo,
.fill_link_info = bpf_raw_tp_link_fill_link_info,
};
#define BPF_RAW_TRACEPOINT_OPEN_LAST_FIELD raw_tracepoint.prog_fd
@ -2570,7 +2647,8 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
err = -ENOMEM;
goto out_put_btp;
}
bpf_link_init(&link->link, &bpf_raw_tp_link_lops, prog);
bpf_link_init(&link->link, BPF_LINK_TYPE_RAW_TRACEPOINT,
&bpf_raw_tp_link_lops, prog);
link->btp = btp;
err = bpf_link_prime(&link->link, &link_primer);
@ -3366,6 +3444,42 @@ static int bpf_btf_get_info_by_fd(struct btf *btf,
return btf_get_info_by_fd(btf, attr, uattr);
}
static int bpf_link_get_info_by_fd(struct bpf_link *link,
const union bpf_attr *attr,
union bpf_attr __user *uattr)
{
struct bpf_link_info __user *uinfo = u64_to_user_ptr(attr->info.info);
struct bpf_link_info info;
u32 info_len = attr->info.info_len;
int err;
err = bpf_check_uarg_tail_zero(uinfo, sizeof(info), info_len);
if (err)
return err;
info_len = min_t(u32, sizeof(info), info_len);
memset(&info, 0, sizeof(info));
if (copy_from_user(&info, uinfo, info_len))
return -EFAULT;
info.type = link->type;
info.id = link->id;
info.prog_id = link->prog->aux->id;
if (link->ops->fill_link_info) {
err = link->ops->fill_link_info(link, &info);
if (err)
return err;
}
if (copy_to_user(uinfo, &info, info_len) ||
put_user(info_len, &uattr->info.info_len))
return -EFAULT;
return 0;
}
#define BPF_OBJ_GET_INFO_BY_FD_LAST_FIELD info.info
static int bpf_obj_get_info_by_fd(const union bpf_attr *attr,
@ -3390,6 +3504,9 @@ static int bpf_obj_get_info_by_fd(const union bpf_attr *attr,
uattr);
else if (f.file->f_op == &btf_fops)
err = bpf_btf_get_info_by_fd(f.file->private_data, attr, uattr);
else if (f.file->f_op == &bpf_link_fops)
err = bpf_link_get_info_by_fd(f.file->private_data,
attr, uattr);
else
err = -EINVAL;

2
kernel/bpf/verifier.c
View File

@ -28,9 +28,11 @@ static const struct bpf_verifier_ops * const bpf_verifier_ops[] = {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
[_id] = & _name ## _verifier_ops,
#define BPF_MAP_TYPE(_id, _ops)
#define BPF_LINK_TYPE(_id, _name)
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
#undef BPF_MAP_TYPE
#undef BPF_LINK_TYPE
};
/* bpf_check() is a static code analyzer that walks eBPF program

31
tools/include/uapi/linux/bpf.h
View File

@ -113,6 +113,8 @@ enum bpf_cmd {
BPF_MAP_DELETE_BATCH,
BPF_LINK_CREATE,
BPF_LINK_UPDATE,
BPF_LINK_GET_FD_BY_ID,
BPF_LINK_GET_NEXT_ID,
};
enum bpf_map_type {
@ -220,6 +222,15 @@ enum bpf_attach_type {
#define MAX_BPF_ATTACH_TYPE __MAX_BPF_ATTACH_TYPE
enum bpf_link_type {
BPF_LINK_TYPE_UNSPEC = 0,
BPF_LINK_TYPE_RAW_TRACEPOINT = 1,
BPF_LINK_TYPE_TRACING = 2,
BPF_LINK_TYPE_CGROUP = 3,
MAX_BPF_LINK_TYPE,
};
/* cgroup-bpf attach flags used in BPF_PROG_ATTACH command
*
* NONE(default): No further bpf programs allowed in the subtree.
@ -523,6 +534,7 @@ union bpf_attr {
__u32 prog_id;
__u32 map_id;
__u32 btf_id;
__u32 link_id;
};
__u32 next_id;
__u32 open_flags;
@ -3609,6 +3621,25 @@ struct bpf_btf_info {
__u32 id;
} __attribute__((aligned(8)));
struct bpf_link_info {
__u32 type;
__u32 id;
__u32 prog_id;
union {
struct {
__aligned_u64 tp_name; /* in/out: tp_name buffer ptr */
__u32 tp_name_len; /* in/out: tp_name buffer len */
} raw_tracepoint;
struct {
__u32 attach_type;
} tracing;
struct {
__u64 cgroup_id;
__u32 attach_type;
} cgroup;
};
} __attribute__((aligned(8)));
/* User bpf_sock_addr struct to access socket fields and sockaddr struct passed
* by user and intended to be used by socket (e.g. to bind to, depends on
* attach attach type).