From e02feb3f1f47509ec1e07b604bfbeff8c3b4e639 Mon Sep 17 00:00:00 2001 From: Dmitrii Dolgov <9erthalion6@gmail.com> Date: Wed, 3 Jan 2024 20:05:47 +0100 Subject: [PATCH] selftests/bpf: Test re-attachment fix for bpf_tracing_prog_attach Add a test case to verify the fix for "prog->aux->dst_trampoline and tgt_prog is NULL" branch in bpf_tracing_prog_attach. The sequence of events: 1. load rawtp program 2. load fentry program with rawtp as target_fd 3. create tracing link for fentry program with target_fd = 0 4. repeat 3 Acked-by: Jiri Olsa Acked-by: Song Liu Signed-off-by: Dmitrii Dolgov <9erthalion6@gmail.com> Link: https://lore.kernel.org/r/20240103190559.14750-5-9erthalion6@gmail.com Signed-off-by: Alexei Starovoitov --- .../bpf/prog_tests/recursive_attach.c | 44 +++++++++++++++++++ .../bpf/progs/fentry_recursive_target.c | 9 ++++ 2 files changed, 53 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/recursive_attach.c b/tools/testing/selftests/bpf/prog_tests/recursive_attach.c index 4bd0a0e4231e..8100509e561b 100644 --- a/tools/testing/selftests/bpf/prog_tests/recursive_attach.c +++ b/tools/testing/selftests/bpf/prog_tests/recursive_attach.c @@ -105,3 +105,47 @@ void test_recursive_fentry(void) if (test__start_subtest("detach")) test_recursive_fentry_chain(true, true); } + +/* Test that a tracing prog reattachment (when we land in + * "prog->aux->dst_trampoline and tgt_prog is NULL" branch in + * bpf_tracing_prog_attach) does not lead to a crash due to missing attach_btf + */ +void test_fentry_attach_btf_presence(void) +{ + struct fentry_recursive_target *target_skel = NULL; + struct fentry_recursive *tracing_skel = NULL; + struct bpf_program *prog; + int err, link_fd, tgt_prog_fd; + + target_skel = fentry_recursive_target__open_and_load(); + if (!ASSERT_OK_PTR(target_skel, "fentry_recursive_target__open_and_load")) + goto close_prog; + + tracing_skel = fentry_recursive__open(); + if (!ASSERT_OK_PTR(tracing_skel, "fentry_recursive__open")) + goto close_prog; + + prog = tracing_skel->progs.recursive_attach; + tgt_prog_fd = bpf_program__fd(target_skel->progs.fentry_target); + err = bpf_program__set_attach_target(prog, tgt_prog_fd, "fentry_target"); + if (!ASSERT_OK(err, "bpf_program__set_attach_target")) + goto close_prog; + + err = fentry_recursive__load(tracing_skel); + if (!ASSERT_OK(err, "fentry_recursive__load")) + goto close_prog; + + tgt_prog_fd = bpf_program__fd(tracing_skel->progs.recursive_attach); + link_fd = bpf_link_create(tgt_prog_fd, 0, BPF_TRACE_FENTRY, NULL); + if (!ASSERT_GE(link_fd, 0, "link_fd")) + goto close_prog; + + fentry_recursive__detach(tracing_skel); + + err = fentry_recursive__attach(tracing_skel); + ASSERT_ERR(err, "fentry_recursive__attach"); + +close_prog: + fentry_recursive_target__destroy(target_skel); + fentry_recursive__destroy(tracing_skel); +} diff --git a/tools/testing/selftests/bpf/progs/fentry_recursive_target.c b/tools/testing/selftests/bpf/progs/fentry_recursive_target.c index cb18a8bfffac..267c876d0aba 100644 --- a/tools/testing/selftests/bpf/progs/fentry_recursive_target.c +++ b/tools/testing/selftests/bpf/progs/fentry_recursive_target.c @@ -14,3 +14,12 @@ int BPF_PROG(test1, int a) { return 0; } + +/* Dummy bpf prog for testing attach_btf presence when attaching an fentry + * program. + */ +SEC("raw_tp/sys_enter") +int BPF_PROG(fentry_target, struct pt_regs *regs, long id) +{ + return 0; +}