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Merge branch 'bpf-jmp-seq-limit'

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Alexei Starovoitov says:

====================
Patch 1 - jmp sequence limit
Patch 2 - improve existing tests
Patch 3 - add pyperf-based realistic bpf program that takes
          advantage of higher limit and use it as a stress test

v1->v2: fixed nit in patch 3. added Andrii's acks
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Daniel Borkmann 2019-05-23 16:20:58 +02:00
commit 29c677c86a
7 changed files with 319 additions and 30 deletions
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7
kernel/bpf/verifier.c
View File

@ -176,7 +176,7 @@ struct bpf_verifier_stack_elem {
struct bpf_verifier_stack_elem *next;
};
#define BPF_COMPLEXITY_LIMIT_STACK 1024
#define BPF_COMPLEXITY_LIMIT_JMP_SEQ 8192
#define BPF_COMPLEXITY_LIMIT_STATES 64
#define BPF_MAP_PTR_UNPRIV 1UL
@ -782,8 +782,9 @@ static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
if (err)
goto err;
elem->st.speculative |= speculative;
if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) {
verbose(env, "BPF program is too complex\n");
if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) {
verbose(env, "The sequence of %d jumps is too complex.\n",
env->stack_size);
goto err;
}
return &elem->st;

31
tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c
View File

@ -12,7 +12,7 @@ static int libbpf_debug_print(enum libbpf_print_level level,
return vfprintf(stderr, "%s", args);
}
static int check_load(const char *file)
static int check_load(const char *file, enum bpf_prog_type type)
{
struct bpf_prog_load_attr attr;
struct bpf_object *obj = NULL;
@ -20,7 +20,7 @@ static int check_load(const char *file)
memset(&attr, 0, sizeof(struct bpf_prog_load_attr));
attr.file = file;
attr.prog_type = BPF_PROG_TYPE_SCHED_CLS;
attr.prog_type = type;
attr.log_level = 4;
err = bpf_prog_load_xattr(&attr, &obj, &prog_fd);
bpf_object__close(obj);
@ -31,19 +31,24 @@ static int check_load(const char *file)
void test_bpf_verif_scale(void)
{
const char *file1 = "./test_verif_scale1.o";
const char *file2 = "./test_verif_scale2.o";
const char *file3 = "./test_verif_scale3.o";
int err;
const char *scale[] = {
"./test_verif_scale1.o", "./test_verif_scale2.o", "./test_verif_scale3.o"
};
const char *pyperf[] = {
"./pyperf50.o", "./pyperf100.o", "./pyperf180.o"
};
int err, i;
if (verifier_stats)
libbpf_set_print(libbpf_debug_print);
err = check_load(file1);
err |= check_load(file2);
err |= check_load(file3);
if (!err)
printf("test_verif_scale:OK\n");
else
printf("test_verif_scale:FAIL\n");
for (i = 0; i < ARRAY_SIZE(scale); i++) {
err = check_load(scale[i], BPF_PROG_TYPE_SCHED_CLS);
printf("test_scale:%s:%s\n", scale[i], err ? "FAIL" : "OK");
}
for (i = 0; i < ARRAY_SIZE(pyperf); i++) {
err = check_load(pyperf[i], BPF_PROG_TYPE_RAW_TRACEPOINT);
printf("test_scale:%s:%s\n", pyperf[i], err ? "FAIL" : "OK");
}
}

268
tools/testing/selftests/bpf/progs/pyperf.h Normal file
View File

@ -0,0 +1,268 @@
// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2019 Facebook
#include <linux/sched.h>
#include <linux/ptrace.h>
#include <stdint.h>
#include <stddef.h>
#include <stdbool.h>
#include <linux/bpf.h>
#include "bpf_helpers.h"
#define FUNCTION_NAME_LEN 64
#define FILE_NAME_LEN 128
#define TASK_COMM_LEN 16
typedef struct {
int PyThreadState_frame;
int PyThreadState_thread;
int PyFrameObject_back;
int PyFrameObject_code;
int PyFrameObject_lineno;
int PyCodeObject_filename;
int PyCodeObject_name;
int String_data;
int String_size;
} OffsetConfig;
typedef struct {
uintptr_t current_state_addr;
uintptr_t tls_key_addr;
OffsetConfig offsets;
bool use_tls;
} PidData;
typedef struct {
uint32_t success;
} Stats;
typedef struct {
char name[FUNCTION_NAME_LEN];
char file[FILE_NAME_LEN];
} Symbol;
typedef struct {
uint32_t pid;
uint32_t tid;
char comm[TASK_COMM_LEN];
int32_t kernel_stack_id;
int32_t user_stack_id;
bool thread_current;
bool pthread_match;
bool stack_complete;
int16_t stack_len;
int32_t stack[STACK_MAX_LEN];
int has_meta;
int metadata;
char dummy_safeguard;
} Event;
struct bpf_elf_map {
__u32 type;
__u32 size_key;
__u32 size_value;
__u32 max_elem;
__u32 flags;
};
typedef int pid_t;
typedef struct {
void* f_back; // PyFrameObject.f_back, previous frame
void* f_code; // PyFrameObject.f_code, pointer to PyCodeObject
void* co_filename; // PyCodeObject.co_filename
void* co_name; // PyCodeObject.co_name
} FrameData;
static inline __attribute__((__always_inline__)) void*
get_thread_state(void* tls_base, PidData* pidData)
{
void* thread_state;
int key;
bpf_probe_read(&key, sizeof(key), (void*)(long)pidData->tls_key_addr);
bpf_probe_read(&thread_state, sizeof(thread_state),
tls_base + 0x310 + key * 0x10 + 0x08);
return thread_state;
}
static inline __attribute__((__always_inline__)) bool
get_frame_data(void* frame_ptr, PidData* pidData, FrameData* frame, Symbol* symbol)
{
// read data from PyFrameObject
bpf_probe_read(&frame->f_back,
sizeof(frame->f_back),
frame_ptr + pidData->offsets.PyFrameObject_back);
bpf_probe_read(&frame->f_code,
sizeof(frame->f_code),
frame_ptr + pidData->offsets.PyFrameObject_code);
// read data from PyCodeObject
if (!frame->f_code)
return false;
bpf_probe_read(&frame->co_filename,
sizeof(frame->co_filename),
frame->f_code + pidData->offsets.PyCodeObject_filename);
bpf_probe_read(&frame->co_name,
sizeof(frame->co_name),
frame->f_code + pidData->offsets.PyCodeObject_name);
// read actual names into symbol
if (frame->co_filename)
bpf_probe_read_str(&symbol->file,
sizeof(symbol->file),
frame->co_filename + pidData->offsets.String_data);
if (frame->co_name)
bpf_probe_read_str(&symbol->name,
sizeof(symbol->name),
frame->co_name + pidData->offsets.String_data);
return true;
}
struct bpf_elf_map SEC("maps") pidmap = {
.type = BPF_MAP_TYPE_HASH,
.size_key = sizeof(int),
.size_value = sizeof(PidData),
.max_elem = 1,
};
struct bpf_elf_map SEC("maps") eventmap = {
.type = BPF_MAP_TYPE_HASH,
.size_key = sizeof(int),
.size_value = sizeof(Event),
.max_elem = 1,
};
struct bpf_elf_map SEC("maps") symbolmap = {
.type = BPF_MAP_TYPE_HASH,
.size_key = sizeof(Symbol),
.size_value = sizeof(int),
.max_elem = 1,
};
struct bpf_elf_map SEC("maps") statsmap = {
.type = BPF_MAP_TYPE_ARRAY,
.size_key = sizeof(Stats),
.size_value = sizeof(int),
.max_elem = 1,
};
struct bpf_elf_map SEC("maps") perfmap = {
.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
.size_key = sizeof(int),
.size_value = sizeof(int),
.max_elem = 32,
};
struct bpf_elf_map SEC("maps") stackmap = {
.type = BPF_MAP_TYPE_STACK_TRACE,
.size_key = sizeof(int),
.size_value = sizeof(long long) * 127,
.max_elem = 1000,
};
static inline __attribute__((__always_inline__)) int __on_event(struct pt_regs *ctx)
{
uint64_t pid_tgid = bpf_get_current_pid_tgid();
pid_t pid = (pid_t)(pid_tgid >> 32);
PidData* pidData = bpf_map_lookup_elem(&pidmap, &pid);
if (!pidData)
return 0;
int zero = 0;
Event* event = bpf_map_lookup_elem(&eventmap, &zero);
if (!event)
return 0;
event->pid = pid;
event->tid = (pid_t)pid_tgid;
bpf_get_current_comm(&event->comm, sizeof(event->comm));
event->user_stack_id = bpf_get_stackid(ctx, &stackmap, BPF_F_USER_STACK);
event->kernel_stack_id = bpf_get_stackid(ctx, &stackmap, 0);
void* thread_state_current = (void*)0;
bpf_probe_read(&thread_state_current,
sizeof(thread_state_current),
(void*)(long)pidData->current_state_addr);
struct task_struct* task = (struct task_struct*)bpf_get_current_task();
void* tls_base = (void*)task;
void* thread_state = pidData->use_tls ? get_thread_state(tls_base, pidData)
: thread_state_current;
event->thread_current = thread_state == thread_state_current;
if (pidData->use_tls) {
uint64_t pthread_created;
uint64_t pthread_self;
bpf_probe_read(&pthread_self, sizeof(pthread_self), tls_base + 0x10);
bpf_probe_read(&pthread_created,
sizeof(pthread_created),
thread_state + pidData->offsets.PyThreadState_thread);
event->pthread_match = pthread_created == pthread_self;
} else {
event->pthread_match = 1;
}
if (event->pthread_match || !pidData->use_tls) {
void* frame_ptr;
FrameData frame;
Symbol sym = {};
int cur_cpu = bpf_get_smp_processor_id();
bpf_probe_read(&frame_ptr,
sizeof(frame_ptr),
thread_state + pidData->offsets.PyThreadState_frame);
int32_t* symbol_counter = bpf_map_lookup_elem(&symbolmap, &sym);
if (symbol_counter == NULL)
return 0;
#pragma unroll
/* Unwind python stack */
for (int i = 0; i < STACK_MAX_LEN; ++i) {
if (frame_ptr && get_frame_data(frame_ptr, pidData, &frame, &sym)) {
int32_t new_symbol_id = *symbol_counter * 64 + cur_cpu;
int32_t *symbol_id = bpf_map_lookup_elem(&symbolmap, &sym);
if (!symbol_id) {
bpf_map_update_elem(&symbolmap, &sym, &zero, 0);
symbol_id = bpf_map_lookup_elem(&symbolmap, &sym);
if (!symbol_id)
return 0;
}
if (*symbol_id == new_symbol_id)
(*symbol_counter)++;
event->stack[i] = *symbol_id;
event->stack_len = i + 1;
frame_ptr = frame.f_back;
}
}
event->stack_complete = frame_ptr == NULL;
} else {
event->stack_complete = 1;
}
Stats* stats = bpf_map_lookup_elem(&statsmap, &zero);
if (stats)
stats->success++;
event->has_meta = 0;
bpf_perf_event_output(ctx, &perfmap, 0, event, offsetof(Event, metadata));
return 0;
}
SEC("raw_tracepoint/kfree_skb")
int on_event(struct pt_regs* ctx)
{
int i, ret = 0;
ret |= __on_event(ctx);
ret |= __on_event(ctx);
ret |= __on_event(ctx);
ret |= __on_event(ctx);
ret |= __on_event(ctx);
return ret;
}
char _license[] SEC("license") = "GPL";

4
tools/testing/selftests/bpf/progs/pyperf100.c Normal file
View File

@ -0,0 +1,4 @@
// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2019 Facebook
#define STACK_MAX_LEN 100
#include "pyperf.h"

4
tools/testing/selftests/bpf/progs/pyperf180.c Normal file
View File

@ -0,0 +1,4 @@
// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2019 Facebook
#define STACK_MAX_LEN 180
#include "pyperf.h"

4
tools/testing/selftests/bpf/progs/pyperf50.c Normal file
View File

@ -0,0 +1,4 @@
// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2019 Facebook
#define STACK_MAX_LEN 50
#include "pyperf.h"

31
tools/testing/selftests/bpf/test_verifier.c
View File

@ -210,33 +210,35 @@ static void bpf_fill_rand_ld_dw(struct bpf_test *self)
self->retval = (uint32_t)res;
}
/* test the sequence of 1k jumps */
#define MAX_JMP_SEQ 8192
/* test the sequence of 8k jumps */
static void bpf_fill_scale1(struct bpf_test *self)
{
struct bpf_insn *insn = self->fill_insns;
int i = 0, k = 0;
insn[i++] = BPF_MOV64_REG(BPF_REG_6, BPF_REG_1);
/* test to check that the sequence of 1024 jumps is acceptable */
while (k++ < 1024) {
/* test to check that the long sequence of jumps is acceptable */
while (k++ < MAX_JMP_SEQ) {
insn[i++] = BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
BPF_FUNC_get_prandom_u32);
insn[i++] = BPF_JMP_IMM(BPF_JGT, BPF_REG_0, bpf_semi_rand_get(), 2);
insn[i++] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, bpf_semi_rand_get(), 2);
insn[i++] = BPF_MOV64_REG(BPF_REG_1, BPF_REG_10);
insn[i++] = BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_6,
-8 * (k % 64 + 1));
}
/* every jump adds 1024 steps to insn_processed, so to stay exactly
* within 1m limit add MAX_TEST_INSNS - 1025 MOVs and 1 EXIT
/* every jump adds 1 step to insn_processed, so to stay exactly
* within 1m limit add MAX_TEST_INSNS - MAX_JMP_SEQ - 1 MOVs and 1 EXIT
*/
while (i < MAX_TEST_INSNS - 1025)
while (i < MAX_TEST_INSNS - MAX_JMP_SEQ - 1)
insn[i++] = BPF_ALU32_IMM(BPF_MOV, BPF_REG_0, 42);
insn[i] = BPF_EXIT_INSN();
self->prog_len = i + 1;
self->retval = 42;
}
/* test the sequence of 1k jumps in inner most function (function depth 8)*/
/* test the sequence of 8k jumps in inner most function (function depth 8)*/
static void bpf_fill_scale2(struct bpf_test *self)
{
struct bpf_insn *insn = self->fill_insns;
@ -248,19 +250,20 @@ static void bpf_fill_scale2(struct bpf_test *self)
insn[i++] = BPF_EXIT_INSN();
}
insn[i++] = BPF_MOV64_REG(BPF_REG_6, BPF_REG_1);
/* test to check that the sequence of 1024 jumps is acceptable */
while (k++ < 1024) {
/* test to check that the long sequence of jumps is acceptable */
k = 0;
while (k++ < MAX_JMP_SEQ) {
insn[i++] = BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
BPF_FUNC_get_prandom_u32);
insn[i++] = BPF_JMP_IMM(BPF_JGT, BPF_REG_0, bpf_semi_rand_get(), 2);
insn[i++] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, bpf_semi_rand_get(), 2);
insn[i++] = BPF_MOV64_REG(BPF_REG_1, BPF_REG_10);
insn[i++] = BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_6,
-8 * (k % (64 - 4 * FUNC_NEST) + 1));
}
/* every jump adds 1024 steps to insn_processed, so to stay exactly
* within 1m limit add MAX_TEST_INSNS - 1025 MOVs and 1 EXIT
/* every jump adds 1 step to insn_processed, so to stay exactly
* within 1m limit add MAX_TEST_INSNS - MAX_JMP_SEQ - 1 MOVs and 1 EXIT
*/
while (i < MAX_TEST_INSNS - 1025)
while (i < MAX_TEST_INSNS - MAX_JMP_SEQ - 1)
insn[i++] = BPF_ALU32_IMM(BPF_MOV, BPF_REG_0, 42);
insn[i] = BPF_EXIT_INSN();
self->prog_len = i + 1;