From 3983c00281d96af2ba611254d679107b5c390627 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Sun, 17 Dec 2023 22:55:37 +0100 Subject: [PATCH 1/2] bpf: Fail uprobe multi link with negative offset Currently the __uprobe_register will return 0 (success) when called with negative offset. The reason is that the call to register_for_each_vma and then build_map_info won't return error for negative offset. They just won't do anything - no matching vma is found so there's no registered breakpoint for the uprobe. I don't think we can change the behaviour of __uprobe_register and fail for negative uprobe offset, because apps might depend on that already. But I think we can still make the change and check for it on bpf multi link syscall level. Also moving the __get_user call and check for the offsets to the top of loop, to fail early without extra __get_user calls for ref_ctr_offset and cookie arrays. Signed-off-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Acked-by: Song Liu Link: https://lore.kernel.org/bpf/20231217215538.3361991-2-jolsa@kernel.org --- kernel/trace/bpf_trace.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 97c0c49c40a0..492d60e9c480 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -3391,15 +3391,19 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr goto error_free; for (i = 0; i < cnt; i++) { - if (ucookies && __get_user(uprobes[i].cookie, ucookies + i)) { + if (__get_user(uprobes[i].offset, uoffsets + i)) { err = -EFAULT; goto error_free; } + if (uprobes[i].offset < 0) { + err = -EINVAL; + goto error_free; + } if (uref_ctr_offsets && __get_user(uprobes[i].ref_ctr_offset, uref_ctr_offsets + i)) { err = -EFAULT; goto error_free; } - if (__get_user(uprobes[i].offset, uoffsets + i)) { + if (ucookies && __get_user(uprobes[i].cookie, ucookies + i)) { err = -EFAULT; goto error_free; } From f17d1a18a3dd6cc4b38a5226b0acbbad3f2063ae Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Sun, 17 Dec 2023 22:55:38 +0100 Subject: [PATCH 2/2] selftests/bpf: Add more uprobe multi fail tests We fail to create uprobe if we pass negative offset. Add more tests validating kernel-side error checking code. Signed-off-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Acked-by: Song Liu Link: https://lore.kernel.org/bpf/20231217215538.3361991-3-jolsa@kernel.org --- .../bpf/prog_tests/uprobe_multi_test.c | 149 +++++++++++++++++- 1 file changed, 146 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c index 07a009f95e85..8269cdee33ae 100644 --- a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c +++ b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c @@ -239,23 +239,166 @@ static void test_attach_api_fails(void) LIBBPF_OPTS(bpf_link_create_opts, opts); const char *path = "/proc/self/exe"; struct uprobe_multi *skel = NULL; + int prog_fd, link_fd = -1; unsigned long offset = 0; - int link_fd = -1; skel = uprobe_multi__open_and_load(); if (!ASSERT_OK_PTR(skel, "uprobe_multi__open_and_load")) goto cleanup; + prog_fd = bpf_program__fd(skel->progs.uprobe_extra); + /* abnormal cnt */ opts.uprobe_multi.path = path; opts.uprobe_multi.offsets = &offset; opts.uprobe_multi.cnt = INT_MAX; - link_fd = bpf_link_create(bpf_program__fd(skel->progs.uprobe), 0, - BPF_TRACE_UPROBE_MULTI, &opts); + link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts); if (!ASSERT_ERR(link_fd, "link_fd")) goto cleanup; if (!ASSERT_EQ(link_fd, -E2BIG, "big cnt")) goto cleanup; + + /* cnt is 0 */ + LIBBPF_OPTS_RESET(opts, + .uprobe_multi.path = path, + .uprobe_multi.offsets = (unsigned long *) &offset, + ); + + link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts); + if (!ASSERT_ERR(link_fd, "link_fd")) + goto cleanup; + if (!ASSERT_EQ(link_fd, -EINVAL, "cnt_is_zero")) + goto cleanup; + + /* negative offset */ + offset = -1; + opts.uprobe_multi.path = path; + opts.uprobe_multi.offsets = (unsigned long *) &offset; + opts.uprobe_multi.cnt = 1; + + link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts); + if (!ASSERT_ERR(link_fd, "link_fd")) + goto cleanup; + if (!ASSERT_EQ(link_fd, -EINVAL, "offset_is_negative")) + goto cleanup; + + /* offsets is NULL */ + LIBBPF_OPTS_RESET(opts, + .uprobe_multi.path = path, + .uprobe_multi.cnt = 1, + ); + + link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts); + if (!ASSERT_ERR(link_fd, "link_fd")) + goto cleanup; + if (!ASSERT_EQ(link_fd, -EINVAL, "offsets_is_null")) + goto cleanup; + + /* wrong offsets pointer */ + LIBBPF_OPTS_RESET(opts, + .uprobe_multi.path = path, + .uprobe_multi.offsets = (unsigned long *) 1, + .uprobe_multi.cnt = 1, + ); + + link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts); + if (!ASSERT_ERR(link_fd, "link_fd")) + goto cleanup; + if (!ASSERT_EQ(link_fd, -EFAULT, "offsets_is_wrong")) + goto cleanup; + + /* path is NULL */ + offset = 1; + LIBBPF_OPTS_RESET(opts, + .uprobe_multi.offsets = (unsigned long *) &offset, + .uprobe_multi.cnt = 1, + ); + + link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts); + if (!ASSERT_ERR(link_fd, "link_fd")) + goto cleanup; + if (!ASSERT_EQ(link_fd, -EINVAL, "path_is_null")) + goto cleanup; + + /* wrong path pointer */ + LIBBPF_OPTS_RESET(opts, + .uprobe_multi.path = (const char *) 1, + .uprobe_multi.offsets = (unsigned long *) &offset, + .uprobe_multi.cnt = 1, + ); + + link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts); + if (!ASSERT_ERR(link_fd, "link_fd")) + goto cleanup; + if (!ASSERT_EQ(link_fd, -EFAULT, "path_is_wrong")) + goto cleanup; + + /* wrong path type */ + LIBBPF_OPTS_RESET(opts, + .uprobe_multi.path = "/", + .uprobe_multi.offsets = (unsigned long *) &offset, + .uprobe_multi.cnt = 1, + ); + + link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts); + if (!ASSERT_ERR(link_fd, "link_fd")) + goto cleanup; + if (!ASSERT_EQ(link_fd, -EBADF, "path_is_wrong_type")) + goto cleanup; + + /* wrong cookies pointer */ + LIBBPF_OPTS_RESET(opts, + .uprobe_multi.path = path, + .uprobe_multi.offsets = (unsigned long *) &offset, + .uprobe_multi.cookies = (__u64 *) 1ULL, + .uprobe_multi.cnt = 1, + ); + + link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts); + if (!ASSERT_ERR(link_fd, "link_fd")) + goto cleanup; + if (!ASSERT_EQ(link_fd, -EFAULT, "cookies_is_wrong")) + goto cleanup; + + /* wrong ref_ctr_offsets pointer */ + LIBBPF_OPTS_RESET(opts, + .uprobe_multi.path = path, + .uprobe_multi.offsets = (unsigned long *) &offset, + .uprobe_multi.cookies = (__u64 *) &offset, + .uprobe_multi.ref_ctr_offsets = (unsigned long *) 1, + .uprobe_multi.cnt = 1, + ); + + link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts); + if (!ASSERT_ERR(link_fd, "link_fd")) + goto cleanup; + if (!ASSERT_EQ(link_fd, -EFAULT, "ref_ctr_offsets_is_wrong")) + goto cleanup; + + /* wrong flags */ + LIBBPF_OPTS_RESET(opts, + .uprobe_multi.flags = 1 << 31, + ); + + link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts); + if (!ASSERT_ERR(link_fd, "link_fd")) + goto cleanup; + if (!ASSERT_EQ(link_fd, -EINVAL, "wrong_flags")) + goto cleanup; + + /* wrong pid */ + LIBBPF_OPTS_RESET(opts, + .uprobe_multi.path = path, + .uprobe_multi.offsets = (unsigned long *) &offset, + .uprobe_multi.cnt = 1, + .uprobe_multi.pid = -2, + ); + + link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts); + if (!ASSERT_ERR(link_fd, "link_fd")) + goto cleanup; + ASSERT_EQ(link_fd, -ESRCH, "pid_is_wrong"); + cleanup: if (link_fd >= 0) close(link_fd);