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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:

  #78/1    fill_link_info/kprobe_link_info:OK
  #78/2    fill_link_info/kretprobe_link_info:OK
  #78/3    fill_link_info/fill_invalid_user_buff:OK
  #78/4    fill_link_info/tracepoint_link_info:OK
  #78/5    fill_link_info/uprobe_link_info:OK
  #78/6    fill_link_info/uretprobe_link_info:OK
  #78      fill_link_info:OK
  Summary: 1/6 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
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@laoar
laoar authored and Kernel Patches Daemon committed Jul 25, 2023
1 parent 91ff287 commit ad51455
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232 changes: 232 additions & 0 deletions tools/testing/selftests/bpf/prog_tests/fill_link_info.c
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// SPDX-License-Identifier: GPL-2.0
/* Copyright (C) 2023 Yafang Shao <laoar.shao@gmail.com> */

#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"
#define KPROBE_FUNC "tcp_rcv_established"
#define UPROBE_FILE "/proc/self/exe"

/* uprobe attach point */
static noinline void uprobe_func(void)
{
asm volatile ("");
}

static int verify_link_info(int fd, enum bpf_perf_event_type type, long addr, ssize_t offset)
{
struct bpf_link_info info;
__u32 len = sizeof(info);
char buf[PATH_MAX];
int err = 0;

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;

switch (info.type) {
case BPF_LINK_TYPE_PERF_EVENT:
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 kptr setting is not permitted or MAX_SYMS is reached */
if (addr)
ASSERT_EQ(info.perf_event.kprobe.addr, addr, "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:
break;
}
break;
default:
switch (type) {
case BPF_PERF_EVENT_KPROBE:
case BPF_PERF_EVENT_KRETPROBE:
case BPF_PERF_EVENT_TRACEPOINT:
case BPF_PERF_EVENT_UPROBE:
case BPF_PERF_EVENT_URETPROBE:
err = -1;
break;
default:
break;
}
break;
}
return err;
}

static void kprobe_fill_invalid_user_buffer(int fd)
{
struct bpf_link_info info;
__u32 len = sizeof(info);
int err = 0;

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 retprobe, bool invalid)
{
DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, opts,
.attach_mode = PROBE_ATTACH_MODE_LINK,
.retprobe = retprobe,
);
int link_fd, err;
long addr;

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 (!ASSERT_GE(link_fd, 0, "link_fd"))
return;

addr = ksym_get_addr(KPROBE_FUNC);
if (!invalid) {
err = verify_link_info(link_fd, type, addr, 0);
ASSERT_OK(err, "verify_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);
if (!ASSERT_GE(link_fd, 0, "link_fd"))
return;

err = verify_link_info(link_fd, BPF_PERF_EVENT_TRACEPOINT, 0, 0);
ASSERT_OK(err, "verify_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, ssize_t offset,
bool retprobe)
{
int link_fd, err;

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

link_fd = bpf_link__fd(skel->links.uprobe_run);
if (!ASSERT_GE(link_fd, 0, "link_fd"))
return;

err = verify_link_info(link_fd, type, 0, offset);
ASSERT_OK(err, "verify_link_info");
bpf_link__detach(skel->links.uprobe_run);
}

void serial_test_fill_link_info(void)
{
struct test_fill_link_info *skel;
ssize_t offset;

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

/* load kallsyms to compare the addr */
if (!ASSERT_OK(load_kallsyms_refresh(), "load_kallsyms_refresh"))
return;
if (test__start_subtest("kprobe_link_info"))
test_kprobe_fill_link_info(skel, BPF_PERF_EVENT_KPROBE, false, false);
if (test__start_subtest("kretprobe_link_info"))
test_kprobe_fill_link_info(skel, BPF_PERF_EVENT_KRETPROBE, true, false);
if (test__start_subtest("fill_invalid_user_buff"))
test_kprobe_fill_link_info(skel, BPF_PERF_EVENT_KPROBE, false, true);
if (test__start_subtest("tracepoint_link_info"))
test_tp_fill_link_info(skel);

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

cleanup:
test_fill_link_info__destroy(skel);
}
25 changes: 25 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 <laoar.shao@gmail.com> */

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

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;
}

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

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