From d633d57902a510debd4ec5b7a374a009c8c2d620 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Thu, 23 Jan 2020 17:15:08 +0100 Subject: [PATCH] selftest/bpf: Add test for allowed trampolines count There's limit of 40 programs tht can be attached to trampoline for one function. Adding test that tries to attach that many plus one extra that needs to fail. Signed-off-by: Jiri Olsa Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200123161508.915203-4-jolsa@kernel.org --- .../bpf/prog_tests/trampoline_count.c | 112 ++++++++++++++++++ .../bpf/progs/test_trampoline_count.c | 21 ++++ 2 files changed, 133 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/trampoline_count.c create mode 100644 tools/testing/selftests/bpf/progs/test_trampoline_count.c diff --git a/tools/testing/selftests/bpf/prog_tests/trampoline_count.c b/tools/testing/selftests/bpf/prog_tests/trampoline_count.c new file mode 100644 index 000000000000..1235f3d1cc50 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/trampoline_count.c @@ -0,0 +1,112 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define _GNU_SOURCE +#include +#include +#include + +#define MAX_TRAMP_PROGS 40 + +struct inst { + struct bpf_object *obj; + struct bpf_link *link_fentry; + struct bpf_link *link_fexit; +}; + +static int test_task_rename(void) +{ + int fd, duration = 0, err; + char buf[] = "test_overhead"; + + fd = open("/proc/self/comm", O_WRONLY|O_TRUNC); + if (CHECK(fd < 0, "open /proc", "err %d", errno)) + return -1; + err = write(fd, buf, sizeof(buf)); + if (err < 0) { + CHECK(err < 0, "task rename", "err %d", errno); + close(fd); + return -1; + } + close(fd); + return 0; +} + +static struct bpf_link *load(struct bpf_object *obj, const char *name) +{ + struct bpf_program *prog; + int duration = 0; + + prog = bpf_object__find_program_by_title(obj, name); + if (CHECK(!prog, "find_probe", "prog '%s' not found\n", name)) + return ERR_PTR(-EINVAL); + return bpf_program__attach_trace(prog); +} + +void test_trampoline_count(void) +{ + const char *fentry_name = "fentry/__set_task_comm"; + const char *fexit_name = "fexit/__set_task_comm"; + const char *object = "test_trampoline_count.o"; + struct inst inst[MAX_TRAMP_PROGS] = { 0 }; + int err, i = 0, duration = 0; + struct bpf_object *obj; + struct bpf_link *link; + char comm[16] = {}; + + /* attach 'allowed' 40 trampoline programs */ + for (i = 0; i < MAX_TRAMP_PROGS; i++) { + obj = bpf_object__open_file(object, NULL); + if (CHECK(IS_ERR(obj), "obj_open_file", "err %ld\n", PTR_ERR(obj))) + goto cleanup; + + err = bpf_object__load(obj); + if (CHECK(err, "obj_load", "err %d\n", err)) + goto cleanup; + inst[i].obj = obj; + + if (rand() % 2) { + link = load(obj, fentry_name); + if (CHECK(IS_ERR(link), "attach prog", "err %ld\n", PTR_ERR(link))) + goto cleanup; + inst[i].link_fentry = link; + } else { + link = load(obj, fexit_name); + if (CHECK(IS_ERR(link), "attach prog", "err %ld\n", PTR_ERR(link))) + goto cleanup; + inst[i].link_fexit = link; + } + } + + /* and try 1 extra.. */ + obj = bpf_object__open_file(object, NULL); + if (CHECK(IS_ERR(obj), "obj_open_file", "err %ld\n", PTR_ERR(obj))) + goto cleanup; + + err = bpf_object__load(obj); + if (CHECK(err, "obj_load", "err %d\n", err)) + goto cleanup_extra; + + /* ..that needs to fail */ + link = load(obj, fentry_name); + if (CHECK(!IS_ERR(link), "cannot attach over the limit", "err %ld\n", PTR_ERR(link))) { + bpf_link__destroy(link); + goto cleanup_extra; + } + + /* with E2BIG error */ + CHECK(PTR_ERR(link) != -E2BIG, "proper error check", "err %ld\n", PTR_ERR(link)); + + /* and finaly execute the probe */ + if (CHECK_FAIL(prctl(PR_GET_NAME, comm, 0L, 0L, 0L))) + goto cleanup_extra; + CHECK_FAIL(test_task_rename()); + CHECK_FAIL(prctl(PR_SET_NAME, comm, 0L, 0L, 0L)); + +cleanup_extra: + bpf_object__close(obj); +cleanup: + while (--i) { + bpf_link__destroy(inst[i].link_fentry); + bpf_link__destroy(inst[i].link_fexit); + bpf_object__close(inst[i].obj); + } +} diff --git a/tools/testing/selftests/bpf/progs/test_trampoline_count.c b/tools/testing/selftests/bpf/progs/test_trampoline_count.c new file mode 100644 index 000000000000..e51e6e3a81c2 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_trampoline_count.c @@ -0,0 +1,21 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include "bpf_trace_helpers.h" + +struct task_struct; + +SEC("fentry/__set_task_comm") +int BPF_PROG(prog1, struct task_struct *tsk, const char *buf, bool exec) +{ + return 0; +} + +SEC("fexit/__set_task_comm") +int BPF_PROG(prog2, struct task_struct *tsk, const char *buf, bool exec) +{ + return 0; +} + +char _license[] SEC("license") = "GPL"; -- 2.45.2