From bdbee82beca4514496c52a2dc035f2a26f0c1b88 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Fri, 10 Dec 2021 22:16:52 +0800 Subject: [PATCH] selftests/bpf: Add test cases for bpf_strncmp() Four test cases are added: (1) ensure the return value is expected (2) ensure no const string size is rejected (3) ensure writable target is rejected (4) ensure no null-terminated target is rejected Signed-off-by: Hou Tao Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20211210141652.877186-5-houtao1@huawei.com --- .../selftests/bpf/prog_tests/test_strncmp.c | 167 +++++++++++++++++++++ tools/testing/selftests/bpf/progs/strncmp_test.c | 54 +++++++ 2 files changed, 221 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/test_strncmp.c create mode 100644 tools/testing/selftests/bpf/progs/strncmp_test.c diff --git a/tools/testing/selftests/bpf/prog_tests/test_strncmp.c b/tools/testing/selftests/bpf/prog_tests/test_strncmp.c new file mode 100644 index 0000000..b57a300 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/test_strncmp.c @@ -0,0 +1,167 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2021. Huawei Technologies Co., Ltd */ +#include +#include "strncmp_test.skel.h" + +static int trigger_strncmp(const struct strncmp_test *skel) +{ + int cmp; + + usleep(1); + + cmp = skel->bss->cmp_ret; + if (cmp > 0) + return 1; + if (cmp < 0) + return -1; + return 0; +} + +/* + * Compare str and target after making str[i] != target[i]. + * When exp is -1, make str[i] < target[i] and delta = -1. + */ +static void strncmp_full_str_cmp(struct strncmp_test *skel, const char *name, + int exp) +{ + size_t nr = sizeof(skel->bss->str); + char *str = skel->bss->str; + int delta = exp; + int got; + size_t i; + + memcpy(str, skel->rodata->target, nr); + for (i = 0; i < nr - 1; i++) { + str[i] += delta; + + got = trigger_strncmp(skel); + ASSERT_EQ(got, exp, name); + + str[i] -= delta; + } +} + +static void test_strncmp_ret(void) +{ + struct strncmp_test *skel; + struct bpf_program *prog; + int err, got; + + skel = strncmp_test__open(); + if (!ASSERT_OK_PTR(skel, "strncmp_test open")) + return; + + bpf_object__for_each_program(prog, skel->obj) + bpf_program__set_autoload(prog, false); + + bpf_program__set_autoload(skel->progs.do_strncmp, true); + + err = strncmp_test__load(skel); + if (!ASSERT_EQ(err, 0, "strncmp_test load")) + goto out; + + err = strncmp_test__attach(skel); + if (!ASSERT_EQ(err, 0, "strncmp_test attach")) + goto out; + + skel->bss->target_pid = getpid(); + + /* Empty str */ + skel->bss->str[0] = '\0'; + got = trigger_strncmp(skel); + ASSERT_EQ(got, -1, "strncmp: empty str"); + + /* Same string */ + memcpy(skel->bss->str, skel->rodata->target, sizeof(skel->bss->str)); + got = trigger_strncmp(skel); + ASSERT_EQ(got, 0, "strncmp: same str"); + + /* Not-null-termainted string */ + memcpy(skel->bss->str, skel->rodata->target, sizeof(skel->bss->str)); + skel->bss->str[sizeof(skel->bss->str) - 1] = 'A'; + got = trigger_strncmp(skel); + ASSERT_EQ(got, 1, "strncmp: not-null-term str"); + + strncmp_full_str_cmp(skel, "strncmp: less than", -1); + strncmp_full_str_cmp(skel, "strncmp: greater than", 1); +out: + strncmp_test__destroy(skel); +} + +static void test_strncmp_bad_not_const_str_size(void) +{ + struct strncmp_test *skel; + struct bpf_program *prog; + int err; + + skel = strncmp_test__open(); + if (!ASSERT_OK_PTR(skel, "strncmp_test open")) + return; + + bpf_object__for_each_program(prog, skel->obj) + bpf_program__set_autoload(prog, false); + + bpf_program__set_autoload(skel->progs.strncmp_bad_not_const_str_size, + true); + + err = strncmp_test__load(skel); + ASSERT_ERR(err, "strncmp_test load bad_not_const_str_size"); + + strncmp_test__destroy(skel); +} + +static void test_strncmp_bad_writable_target(void) +{ + struct strncmp_test *skel; + struct bpf_program *prog; + int err; + + skel = strncmp_test__open(); + if (!ASSERT_OK_PTR(skel, "strncmp_test open")) + return; + + bpf_object__for_each_program(prog, skel->obj) + bpf_program__set_autoload(prog, false); + + bpf_program__set_autoload(skel->progs.strncmp_bad_writable_target, + true); + + err = strncmp_test__load(skel); + ASSERT_ERR(err, "strncmp_test load bad_writable_target"); + + strncmp_test__destroy(skel); +} + +static void test_strncmp_bad_not_null_term_target(void) +{ + struct strncmp_test *skel; + struct bpf_program *prog; + int err; + + skel = strncmp_test__open(); + if (!ASSERT_OK_PTR(skel, "strncmp_test open")) + return; + + bpf_object__for_each_program(prog, skel->obj) + bpf_program__set_autoload(prog, false); + + bpf_program__set_autoload(skel->progs.strncmp_bad_not_null_term_target, + true); + + err = strncmp_test__load(skel); + ASSERT_ERR(err, "strncmp_test load bad_not_null_term_target"); + + strncmp_test__destroy(skel); +} + +void test_test_strncmp(void) +{ + if (test__start_subtest("strncmp_ret")) + test_strncmp_ret(); + if (test__start_subtest("strncmp_bad_not_const_str_size")) + test_strncmp_bad_not_const_str_size(); + if (test__start_subtest("strncmp_bad_writable_target")) + test_strncmp_bad_writable_target(); + if (test__start_subtest("strncmp_bad_not_null_term_target")) + test_strncmp_bad_not_null_term_target(); +} diff --git a/tools/testing/selftests/bpf/progs/strncmp_test.c b/tools/testing/selftests/bpf/progs/strncmp_test.c new file mode 100644 index 0000000..900d930 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/strncmp_test.c @@ -0,0 +1,54 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2021. Huawei Technologies Co., Ltd */ +#include +#include +#include +#include +#include + +#define STRNCMP_STR_SZ 8 + +const char target[STRNCMP_STR_SZ] = "EEEEEEE"; +char str[STRNCMP_STR_SZ]; +int cmp_ret = 0; +int target_pid = 0; + +const char no_str_target[STRNCMP_STR_SZ] = "12345678"; +char writable_target[STRNCMP_STR_SZ]; +unsigned int no_const_str_size = STRNCMP_STR_SZ; + +char _license[] SEC("license") = "GPL"; + +SEC("tp/syscalls/sys_enter_nanosleep") +int do_strncmp(void *ctx) +{ + if ((bpf_get_current_pid_tgid() >> 32) != target_pid) + return 0; + + cmp_ret = bpf_strncmp(str, STRNCMP_STR_SZ, target); + return 0; +} + +SEC("tp/syscalls/sys_enter_nanosleep") +int strncmp_bad_not_const_str_size(void *ctx) +{ + /* The value of string size is not const, so will fail */ + cmp_ret = bpf_strncmp(str, no_const_str_size, target); + return 0; +} + +SEC("tp/syscalls/sys_enter_nanosleep") +int strncmp_bad_writable_target(void *ctx) +{ + /* Compared target is not read-only, so will fail */ + cmp_ret = bpf_strncmp(str, STRNCMP_STR_SZ, writable_target); + return 0; +} + +SEC("tp/syscalls/sys_enter_nanosleep") +int strncmp_bad_not_null_term_target(void *ctx) +{ + /* Compared target is not null-terminated, so will fail */ + cmp_ret = bpf_strncmp(str, STRNCMP_STR_SZ, no_str_target); + return 0; +} -- 2.7.4