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selftests/bpf: Add selftest for fill_link_info
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Add selftest for the fill_link_info of uprobe, kprobe and tracepoint.
The result:

  $ tools/testing/selftests/bpf/test_progs --name=fill_link_info
  #79/1    fill_link_info/kprobe_link_info:OK
  #79/2    fill_link_info/kretprobe_link_info:OK
  #79/3    fill_link_info/kprobe_invalid_ubuff:OK
  #79/4    fill_link_info/tracepoint_link_info:OK
  #79/5    fill_link_info/uprobe_link_info:OK
  #79/6    fill_link_info/uretprobe_link_info:OK
  #79/7    fill_link_info/kprobe_multi_link_info:OK
  #79/8    fill_link_info/kretprobe_multi_link_info:OK
  #79/9    fill_link_info/kprobe_multi_invalid_ubuff:OK
  #79      fill_link_info:OK
  Summary: 1/9 PASSED, 0 SKIPPED, 0 FAILED

The test case for kprobe_multi won't be run on aarch64, as it is not
supported.

Signed-off-by: Yafang Shao <[email protected]>
Acked-by: Yonghong Song <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
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@laoar
laoar authored and Kernel Patches Daemon committed Aug 14, 2023
1 parent 72d69fb commit 900f620
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Showing 3 changed files with 387 additions and 0 deletions.
3 changes: 3 additions & 0 deletions tools/testing/selftests/bpf/DENYLIST.aarch64
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Original file line number Diff line number Diff line change
Expand Up @@ -12,3 +12,6 @@ kprobe_multi_test/skel_api # libbpf: failed to load BPF sk
module_attach # prog 'kprobe_multi': failed to auto-attach: -95
fentry_test/fentry_many_args # fentry_many_args:FAIL:fentry_many_args_attach unexpected error: -524
fexit_test/fexit_many_args # fexit_many_args:FAIL:fexit_many_args_attach unexpected error: -524
fill_link_info/kprobe_multi_link_info # bpf_program__attach_kprobe_multi_opts unexpected error: -95
fill_link_info/kretprobe_multi_link_info # bpf_program__attach_kprobe_multi_opts unexpected error: -95
fill_link_info/kprobe_multi_invalid_ubuff # bpf_program__attach_kprobe_multi_opts unexpected error: -95
342 changes: 342 additions & 0 deletions tools/testing/selftests/bpf/prog_tests/fill_link_info.c
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@@ -0,0 +1,342 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright (C) 2023 Yafang Shao <[email protected]> */

#include <string.h>
#include <linux/bpf.h>
#include <linux/limits.h>
#include <test_progs.h>
#include "trace_helpers.h"
#include "test_fill_link_info.skel.h"

#define TP_CAT "sched"
#define TP_NAME "sched_switch"

static const char *kmulti_syms[] = {
"bpf_fentry_test2",
"bpf_fentry_test1",
"bpf_fentry_test3",
};
#define KMULTI_CNT ARRAY_SIZE(kmulti_syms)
static __u64 kmulti_addrs[KMULTI_CNT];

#define KPROBE_FUNC "bpf_fentry_test1"
static __u64 kprobe_addr;

#define UPROBE_FILE "/proc/self/exe"
static ssize_t uprobe_offset;
/* uprobe attach point */
static noinline void uprobe_func(void)
{
asm volatile ("");
}

static int verify_perf_link_info(int fd, enum bpf_perf_event_type type, long addr,
ssize_t offset, ssize_t entry_offset)
{
struct bpf_link_info info;
__u32 len = sizeof(info);
char buf[PATH_MAX];
int err;

memset(&info, 0, sizeof(info));
buf[0] = '\0';

again:
err = bpf_link_get_info_by_fd(fd, &info, &len);
if (!ASSERT_OK(err, "get_link_info"))
return -1;

if (!ASSERT_EQ(info.type, BPF_LINK_TYPE_PERF_EVENT, "link_type"))
return -1;
if (!ASSERT_EQ(info.perf_event.type, type, "perf_type_match"))
return -1;

switch (info.perf_event.type) {
case BPF_PERF_EVENT_KPROBE:
case BPF_PERF_EVENT_KRETPROBE:
ASSERT_EQ(info.perf_event.kprobe.offset, offset, "kprobe_offset");

/* In case kernel.kptr_restrict is not permitted or MAX_SYMS is reached */
if (addr)
ASSERT_EQ(info.perf_event.kprobe.addr, addr + entry_offset,
"kprobe_addr");

if (!info.perf_event.kprobe.func_name) {
ASSERT_EQ(info.perf_event.kprobe.name_len, 0, "name_len");
info.perf_event.kprobe.func_name = ptr_to_u64(&buf);
info.perf_event.kprobe.name_len = sizeof(buf);
goto again;
}

err = strncmp(u64_to_ptr(info.perf_event.kprobe.func_name), KPROBE_FUNC,
strlen(KPROBE_FUNC));
ASSERT_EQ(err, 0, "cmp_kprobe_func_name");
break;
case BPF_PERF_EVENT_TRACEPOINT:
if (!info.perf_event.tracepoint.tp_name) {
ASSERT_EQ(info.perf_event.tracepoint.name_len, 0, "name_len");
info.perf_event.tracepoint.tp_name = ptr_to_u64(&buf);
info.perf_event.tracepoint.name_len = sizeof(buf);
goto again;
}

err = strncmp(u64_to_ptr(info.perf_event.tracepoint.tp_name), TP_NAME,
strlen(TP_NAME));
ASSERT_EQ(err, 0, "cmp_tp_name");
break;
case BPF_PERF_EVENT_UPROBE:
case BPF_PERF_EVENT_URETPROBE:
ASSERT_EQ(info.perf_event.uprobe.offset, offset, "uprobe_offset");

if (!info.perf_event.uprobe.file_name) {
ASSERT_EQ(info.perf_event.uprobe.name_len, 0, "name_len");
info.perf_event.uprobe.file_name = ptr_to_u64(&buf);
info.perf_event.uprobe.name_len = sizeof(buf);
goto again;
}

err = strncmp(u64_to_ptr(info.perf_event.uprobe.file_name), UPROBE_FILE,
strlen(UPROBE_FILE));
ASSERT_EQ(err, 0, "cmp_file_name");
break;
default:
err = -1;
break;
}
return err;
}

static void kprobe_fill_invalid_user_buffer(int fd)
{
struct bpf_link_info info;
__u32 len = sizeof(info);
int err;

memset(&info, 0, sizeof(info));

info.perf_event.kprobe.func_name = 0x1; /* invalid address */
err = bpf_link_get_info_by_fd(fd, &info, &len);
ASSERT_EQ(err, -EINVAL, "invalid_buff_and_len");

info.perf_event.kprobe.name_len = 64;
err = bpf_link_get_info_by_fd(fd, &info, &len);
ASSERT_EQ(err, -EFAULT, "invalid_buff");

info.perf_event.kprobe.func_name = 0;
err = bpf_link_get_info_by_fd(fd, &info, &len);
ASSERT_EQ(err, -EINVAL, "invalid_len");

ASSERT_EQ(info.perf_event.kprobe.addr, 0, "func_addr");
ASSERT_EQ(info.perf_event.kprobe.offset, 0, "func_offset");
ASSERT_EQ(info.perf_event.type, 0, "type");
}

static void test_kprobe_fill_link_info(struct test_fill_link_info *skel,
enum bpf_perf_event_type type,
bool invalid)
{
DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, opts,
.attach_mode = PROBE_ATTACH_MODE_LINK,
.retprobe = type == BPF_PERF_EVENT_KRETPROBE,
);
ssize_t entry_offset = 0;
int link_fd, err;

skel->links.kprobe_run = bpf_program__attach_kprobe_opts(skel->progs.kprobe_run,
KPROBE_FUNC, &opts);
if (!ASSERT_OK_PTR(skel->links.kprobe_run, "attach_kprobe"))
return;

link_fd = bpf_link__fd(skel->links.kprobe_run);
if (!invalid) {
/* See also arch_adjust_kprobe_addr(). */
if (skel->kconfig->CONFIG_X86_KERNEL_IBT)
entry_offset = 4;
err = verify_perf_link_info(link_fd, type, kprobe_addr, 0, entry_offset);
ASSERT_OK(err, "verify_perf_link_info");
} else {
kprobe_fill_invalid_user_buffer(link_fd);
}
bpf_link__detach(skel->links.kprobe_run);
}

static void test_tp_fill_link_info(struct test_fill_link_info *skel)
{
int link_fd, err;

skel->links.tp_run = bpf_program__attach_tracepoint(skel->progs.tp_run, TP_CAT, TP_NAME);
if (!ASSERT_OK_PTR(skel->links.tp_run, "attach_tp"))
return;

link_fd = bpf_link__fd(skel->links.tp_run);
err = verify_perf_link_info(link_fd, BPF_PERF_EVENT_TRACEPOINT, 0, 0, 0);
ASSERT_OK(err, "verify_perf_link_info");
bpf_link__detach(skel->links.tp_run);
}

static void test_uprobe_fill_link_info(struct test_fill_link_info *skel,
enum bpf_perf_event_type type)
{
int link_fd, err;

skel->links.uprobe_run = bpf_program__attach_uprobe(skel->progs.uprobe_run,
type == BPF_PERF_EVENT_URETPROBE,
0, /* self pid */
UPROBE_FILE, uprobe_offset);
if (!ASSERT_OK_PTR(skel->links.uprobe_run, "attach_uprobe"))
return;

link_fd = bpf_link__fd(skel->links.uprobe_run);
err = verify_perf_link_info(link_fd, type, 0, uprobe_offset, 0);
ASSERT_OK(err, "verify_perf_link_info");
bpf_link__detach(skel->links.uprobe_run);
}

static int verify_kmulti_link_info(int fd, bool retprobe)
{
struct bpf_link_info info;
__u32 len = sizeof(info);
__u64 addrs[KMULTI_CNT];
int flags, i, err;

memset(&info, 0, sizeof(info));

again:
err = bpf_link_get_info_by_fd(fd, &info, &len);
if (!ASSERT_OK(err, "get_link_info"))
return -1;

if (!ASSERT_EQ(info.type, BPF_LINK_TYPE_KPROBE_MULTI, "kmulti_type"))
return -1;

ASSERT_EQ(info.kprobe_multi.count, KMULTI_CNT, "func_cnt");
flags = info.kprobe_multi.flags & BPF_F_KPROBE_MULTI_RETURN;
if (!retprobe)
ASSERT_EQ(flags, 0, "kmulti_flags");
else
ASSERT_NEQ(flags, 0, "kretmulti_flags");

if (!info.kprobe_multi.addrs) {
info.kprobe_multi.addrs = ptr_to_u64(addrs);
goto again;
}
for (i = 0; i < KMULTI_CNT; i++)
ASSERT_EQ(addrs[i], kmulti_addrs[i], "kmulti_addrs");
return 0;
}

static void verify_kmulti_invalid_user_buffer(int fd)
{
struct bpf_link_info info;
__u32 len = sizeof(info);
__u64 addrs[KMULTI_CNT];
int err, i;

memset(&info, 0, sizeof(info));

info.kprobe_multi.count = KMULTI_CNT;
err = bpf_link_get_info_by_fd(fd, &info, &len);
ASSERT_EQ(err, -EINVAL, "no_addr");

info.kprobe_multi.addrs = ptr_to_u64(addrs);
info.kprobe_multi.count = 0;
err = bpf_link_get_info_by_fd(fd, &info, &len);
ASSERT_EQ(err, -EINVAL, "no_cnt");

for (i = 0; i < KMULTI_CNT; i++)
addrs[i] = 0;
info.kprobe_multi.count = KMULTI_CNT - 1;
err = bpf_link_get_info_by_fd(fd, &info, &len);
ASSERT_EQ(err, -ENOSPC, "smaller_cnt");
for (i = 0; i < KMULTI_CNT - 1; i++)
ASSERT_EQ(addrs[i], kmulti_addrs[i], "kmulti_addrs");
ASSERT_EQ(addrs[i], 0, "kmulti_addrs");

for (i = 0; i < KMULTI_CNT; i++)
addrs[i] = 0;
info.kprobe_multi.count = KMULTI_CNT + 1;
err = bpf_link_get_info_by_fd(fd, &info, &len);
ASSERT_EQ(err, 0, "bigger_cnt");
for (i = 0; i < KMULTI_CNT; i++)
ASSERT_EQ(addrs[i], kmulti_addrs[i], "kmulti_addrs");

info.kprobe_multi.count = KMULTI_CNT;
info.kprobe_multi.addrs = 0x1; /* invalid addr */
err = bpf_link_get_info_by_fd(fd, &info, &len);
ASSERT_EQ(err, -EFAULT, "invalid_buff");
}

static int symbols_cmp_r(const void *a, const void *b)
{
const char **str_a = (const char **) a;
const char **str_b = (const char **) b;

return strcmp(*str_a, *str_b);
}

static void test_kprobe_multi_fill_link_info(struct test_fill_link_info *skel,
bool retprobe, bool invalid)
{
LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
int link_fd, err;

opts.syms = kmulti_syms;
opts.cnt = KMULTI_CNT;
opts.retprobe = retprobe;
skel->links.kmulti_run = bpf_program__attach_kprobe_multi_opts(skel->progs.kmulti_run,
NULL, &opts);
if (!ASSERT_OK_PTR(skel->links.kmulti_run, "attach_kprobe_multi"))
return;

link_fd = bpf_link__fd(skel->links.kmulti_run);
if (!invalid) {
err = verify_kmulti_link_info(link_fd, retprobe);
ASSERT_OK(err, "verify_kmulti_link_info");
} else {
verify_kmulti_invalid_user_buffer(link_fd);
}
bpf_link__detach(skel->links.kmulti_run);
}

void test_fill_link_info(void)
{
struct test_fill_link_info *skel;
int i;

skel = test_fill_link_info__open_and_load();
if (!ASSERT_OK_PTR(skel, "skel_open"))
return;

/* load kallsyms to compare the addr */
if (!ASSERT_OK(load_kallsyms_refresh(), "load_kallsyms_refresh"))
goto cleanup;

kprobe_addr = ksym_get_addr(KPROBE_FUNC);
if (test__start_subtest("kprobe_link_info"))
test_kprobe_fill_link_info(skel, BPF_PERF_EVENT_KPROBE, false);
if (test__start_subtest("kretprobe_link_info"))
test_kprobe_fill_link_info(skel, BPF_PERF_EVENT_KRETPROBE, false);
if (test__start_subtest("kprobe_invalid_ubuff"))
test_kprobe_fill_link_info(skel, BPF_PERF_EVENT_KPROBE, true);
if (test__start_subtest("tracepoint_link_info"))
test_tp_fill_link_info(skel);

uprobe_offset = get_uprobe_offset(&uprobe_func);
if (test__start_subtest("uprobe_link_info"))
test_uprobe_fill_link_info(skel, BPF_PERF_EVENT_UPROBE);
if (test__start_subtest("uretprobe_link_info"))
test_uprobe_fill_link_info(skel, BPF_PERF_EVENT_URETPROBE);

qsort(kmulti_syms, KMULTI_CNT, sizeof(kmulti_syms[0]), symbols_cmp_r);
for (i = 0; i < KMULTI_CNT; i++)
kmulti_addrs[i] = ksym_get_addr(kmulti_syms[i]);
if (test__start_subtest("kprobe_multi_link_info"))
test_kprobe_multi_fill_link_info(skel, false, false);
if (test__start_subtest("kretprobe_multi_link_info"))
test_kprobe_multi_fill_link_info(skel, true, false);
if (test__start_subtest("kprobe_multi_invalid_ubuff"))
test_kprobe_multi_fill_link_info(skel, true, true);

cleanup:
test_fill_link_info__destroy(skel);
}
42 changes: 42 additions & 0 deletions tools/testing/selftests/bpf/progs/test_fill_link_info.c
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// SPDX-License-Identifier: GPL-2.0
/* Copyright (C) 2023 Yafang Shao <[email protected]> */

#include "vmlinux.h"
#include <bpf/bpf_tracing.h>
#include <stdbool.h>

extern bool CONFIG_X86_KERNEL_IBT __kconfig __weak;

/* This function is here to have CONFIG_X86_KERNEL_IBT
* used and added to object BTF.
*/
int unused(void)
{
return CONFIG_X86_KERNEL_IBT ? 0 : 1;
}

SEC("kprobe")
int BPF_PROG(kprobe_run)
{
return 0;
}

SEC("uprobe")
int BPF_PROG(uprobe_run)
{
return 0;
}

SEC("tracepoint")
int BPF_PROG(tp_run)
{
return 0;
}

SEC("kprobe.multi")
int BPF_PROG(kmulti_run)
{
return 0;
}

char _license[] SEC("license") = "GPL";

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