On Thu, Aug 3, 2023 at 7:00 AM Yonghong Song <yonghong.song@xxxxxxxxx> wrote:
>
>
>
> On 7/31/23 4:13 AM, Yafang Shao wrote:
> > 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_fill_invalid_user_buff: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_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 <laoar.shao@xxxxxxxxx>
> > ---
> > tools/testing/selftests/bpf/DENYLIST.aarch64 | 3 +
> > .../selftests/bpf/prog_tests/fill_link_info.c | 369 +++++++++++++++++++++
> > .../selftests/bpf/progs/test_fill_link_info.c | 42 +++
> > 3 files changed, 414 insertions(+)
> > create mode 100644 tools/testing/selftests/bpf/prog_tests/fill_link_info.c
> > create mode 100644 tools/testing/selftests/bpf/progs/test_fill_link_info.c
> >
> > diff --git a/tools/testing/selftests/bpf/DENYLIST.aarch64 b/tools/testing/selftests/bpf/DENYLIST.aarch64
> > index 3b61e8b..b2f46b6 100644
> > --- a/tools/testing/selftests/bpf/DENYLIST.aarch64
> > +++ b/tools/testing/selftests/bpf/DENYLIST.aarch64
> > @@ -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_ubuff # bpf_program__attach_kprobe_multi_opts unexpected error: -95
> > diff --git a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
> > new file mode 100644
> > index 0000000..948ae60
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
> > @@ -0,0 +1,369 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (C) 2023 Yafang Shao <laoar.shao@xxxxxxxxx> */
> > +
> > +#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"
> > +#define KMULTI_CNT (4)
> > +
> > +/* 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 = 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 */
>
> 'kptr' has special meaning in bpf ecosystem (searching verifier.c).
> Could you re-word the above comments? I am not sure what it means.
It is the kernel.kptr_restrict sysctl knob.
Will re-word it.
>
> > + 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:
> > + 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;
>
> Is this whole 'default' thing ever possible?
> Maybe you should have ASSERT_EQ(info.type, BPF_LINK_TYPE_PERF_EVENT)
> first and then you won't need a top switch statement?
Will change it.
>
>
> > + }
> > + 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 retprobe, bool invalid)
> > +{
> > + DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, opts,
> > + .attach_mode = PROBE_ATTACH_MODE_LINK,
> > + .retprobe = retprobe,
> > + );
> > + ssize_t offset = 0, entry_offset = 0;
> > + 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;
>
> There is no need to check validity of link_fd if skel->links.kprobe_run
> is valid.
Will change it and the others.
>
> > +
> > + addr = ksym_get_addr(KPROBE_FUNC);
> > + 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, addr, offset, offset ?: entry_offset);
>
> offset is always 0 here.
Will simplify it.
>
> > + 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);
> > + if (!ASSERT_GE(link_fd, 0, "link_fd"))
> > + return;
>
> No need to check link_fd.
>
> > +
> > + 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, 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;
>
> No need to check link_fd.
>
> > +
> > + err = verify_perf_link_info(link_fd, type, 0, offset, 0);
> > + ASSERT_OK(err, "verify_perf_link_info");
> > + bpf_link__detach(skel->links.uprobe_run);
> > +}
> > +
> > +static int verify_kmulti_link_info(int fd, const __u64 *addrs, bool retprobe)
> > +{
> > + __u64 kmulti_addrs[KMULTI_CNT];
> > + struct bpf_link_info info;
> > + __u32 len = sizeof(info);
> > + int flags, i, err = 0;
> > +
> > + 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;
> > +
> > + ASSERT_EQ(info.type, BPF_LINK_TYPE_KPROBE_MULTI, "kmulti_type");
>
> You can do
> if (!ASSERT_EQ(info.type, BPF_LINK_TYPE_KPROBE_MULTI, "kmulti_type"))
> return -1;
>
> and then there is no need for below switch statement.
Will change it.
>
> > + switch (info.type) {
> > + case BPF_LINK_TYPE_KPROBE_MULTI:
> > + 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(kmulti_addrs);
> > + goto again;
> > + }
> > + for (i = 0; i < KMULTI_CNT; i++)
> > + ASSERT_EQ(kmulti_addrs[i], addrs[i], "kmulti_addrs");
> > + break;
> > + default:
> > + err = -1;
> > + break;
> > + }
> > + return err;
> > +}
> > +
> > +static void verify_kmulti_user_buffer(int fd, const __u64 *addrs)
> > +{
> > + __u64 kmulti_addrs[KMULTI_CNT];
> > + struct bpf_link_info info;
> > + __u32 len = sizeof(info);
> > + 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(kmulti_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++)
> > + kmulti_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(kmulti_addrs[i], addrs[i], "kmulti_addrs");
> > + ASSERT_EQ(kmulti_addrs[i], 0, "kmulti_addrs");
> > +
> > + for (i = 0; i < KMULTI_CNT; i++)
> > + kmulti_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(kmulti_addrs[i], 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 buffer)
> > +{
> > + LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
> > + const char *syms[KMULTI_CNT] = {
> > + "schedule_timeout_interruptible",
> > + "schedule_timeout_uninterruptible",
> > + "schedule_timeout_idle",
> > + "schedule_timeout_killable",
> > + };
> > + __u64 addrs[KMULTI_CNT];
> > + int link_fd, i, err = 0;
> > +
> > + qsort(syms, KMULTI_CNT, sizeof(syms[0]), symbols_cmp_r);
> > + opts.syms = 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 (!ASSERT_GE(link_fd, 0, "link_fd"))
> > + return;
>
> No need to check link_fd.
>
> > +
> > + for (i = 0; i < KMULTI_CNT; i++)
> > + addrs[i] = ksym_get_addr(syms[i]);
> > +
> > + if (!buffer)
> > + err = verify_kmulti_link_info(link_fd, addrs, retprobe);
> > + else
> > + verify_kmulti_user_buffer(link_fd, addrs);
> > + ASSERT_OK(err, "verify_kmulti_link_info");
> > + bpf_link__detach(skel->links.kmulti_run);
> > +}
> > +
> > +void 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;
>
> Just return here if skel is invalid.
Will change it.
>
> > +
> > + /* load kallsyms to compare the addr */
> > + if (!ASSERT_OK(load_kallsyms_refresh(), "load_kallsyms_refresh"))
> > + return;
>
> You actually need to go to 'cleanup' here.
will change it.
--
Regards
Yafang
