Four test cases are added:
(1) ensure the return value is expected
(2) ensure no const size is rejected
(3) ensure writable str is rejected
(4) ensure no null-terminated str is rejected
Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
---
.../selftests/bpf/prog_tests/test_strncmp.c | 170 ++++++++++++++++++
.../selftests/bpf/progs/strncmp_test.c | 59 ++++++
2 files changed, 229 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 000000000000..3ed54b55f96a
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/test_strncmp.c
@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2021. Huawei Technologies Co., Ltd */
+#include <test_progs.h>
+#include "strncmp_test.skel.h"
+
+static struct strncmp_test *strncmp_test_open_and_disable_autoload(void)
+{
+ struct strncmp_test *skel;
+ struct bpf_program *prog;
+
+ skel = strncmp_test__open();
+ if (libbpf_get_error(skel))
+ return skel;
+
+ bpf_object__for_each_program(prog, skel->obj)
+ bpf_program__set_autoload(prog, false);
+
+ return skel;
+}
+
+static inline int to_tristate_ret(int ret)
+{
+ if (ret > 0)
+ return 1;
+ if (ret < 0)
+ return -1;
+ return 0;
+}
+
+static int trigger_strncmp(const struct strncmp_test *skel)
+{
+ struct timespec wait = {.tv_sec = 0, .tv_nsec = 1};
+
+ nanosleep(&wait, NULL);
+ return to_tristate_ret(skel->bss->cmp_ret);
+}
+
+/*
+ * Compare str and target after making str[i] != target[i].
+ * When exp is -1, make str[i] < target[i] and delta is -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;
+ int err, got;
+
+ skel = strncmp_test_open_and_disable_autoload();
+ if (!ASSERT_OK_PTR(skel, "strncmp_test open"))
+ return;
+
+ 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;
+ int err;
+
+ skel = strncmp_test_open_and_disable_autoload();
+ if (!ASSERT_OK_PTR(skel, "strncmp_test open"))
+ return;
+
+ 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;
+ int err;
+
+ skel = strncmp_test_open_and_disable_autoload();
+ if (!ASSERT_OK_PTR(skel, "strncmp_test open"))
+ return;
+
+ 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;
+ int err;
+
+ skel = strncmp_test_open_and_disable_autoload();
+ if (!ASSERT_OK_PTR(skel, "strncmp_test open"))
+ return;
+
+ bpf_program__set_autoload(skel->progs.strncmp_bad_not_null_term_target,
+ true);
+ skel->rodata->target[sizeof(skel->rodata->target) - 1] = 'A';
+
+ 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 000000000000..8cdf950a0ce1
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/strncmp_test.c
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2021. Huawei Technologies Co., Ltd */
+#include <stdbool.h>
+#include <linux/types.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+#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;
+
+char bad_target[STRNCMP_STR_SZ];
+unsigned int bad_cmp_str_size = STRNCMP_STR_SZ;
+
+char _license[] SEC("license") = "GPL";
+
+static __always_inline bool called_by_target_pid(void)
+{
+ __u32 pid = bpf_get_current_pid_tgid() >> 32;
+
+ return pid == target_pid;
+}
+
+SEC("tp/syscalls/sys_enter_nanosleep")
+int do_strncmp(void *ctx)
+{
+ if (!called_by_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)
+{
+ cmp_ret = bpf_strncmp(str, bad_cmp_str_size, target);
+ return 0;
+}
+
+SEC("tp/syscalls/sys_enter_nanosleep")
+int strncmp_bad_writable_target(void *ctx)
+{
+ cmp_ret = bpf_strncmp(str, STRNCMP_STR_SZ, bad_target);
+ return 0;
+}
+
+SEC("tp/syscalls/sys_enter_nanosleep")
+int strncmp_bad_not_null_term_target(void *ctx)
+{
+ cmp_ret = bpf_strncmp(str, STRNCMP_STR_SZ, target);
+ return 0;
+}
--
2.29.2
