Re: [PATCH bpf-next v3 2/3] selftests/bpf: convert test_dev_cgroup to test_progs

On 7/30/24 4:59 AM, Alexis Lothoré (eBPF Foundation) wrote:

+static void test_read(const char *path, char *buf, int buf_size,

•       int expected_ret)
  

+{

• int ret, fd;
• fd = open(path, O_RDONLY);
• /* A bare open on unauthorized device should fail */
• if (expected_ret < 0) {

• ASSERT_EQ(fd, expected_ret, "open file for read");
  

One nit. expected_ret is actually expected_errno. It just happens -EPERM is -1, so testing fd against expected_errno works here but is confusing to read. How about separating the fd and errno test in the access rejected case. First test for fd == -1 and then test for errno == expected_errno.

Please also carry Stanislav's Ack in patch 1 and 3 in the next respin.

Thanks for helping to move this test to test_progs.

pw-bot: cr

• if (fd >= 0)
  

• 	close(fd);
  

• return;
  

• }
• if (!ASSERT_OK_FD(fd, "open file for read"))

• return;
  

• ret = read(fd, buf, buf_size);
• ASSERT_EQ(ret, expected_ret, "read");
• close(fd);

+}

+static void test_write(const char *path, char *buf, int buf_size,

•        int expected_ret)
  

+{

• int ret, fd;
• fd = open(path, O_WRONLY);
• /* A bare open on unauthorized device should fail */
• if (expected_ret < 0) {

• ASSERT_EQ(fd, expected_ret, "open file for write");
  

• if (fd >= 0)
  

• 	close(fd);
  

• return;
  

• }
• if (!ASSERT_OK_FD(fd, "open file for write"))

• return;
  

• ret = write(fd, buf, buf_size);
• ASSERT_EQ(ret, expected_ret, "write");
• close(fd);

+}

+void test_cgroup_dev(void) +{

• char buf[TEST_BUFFER_SIZE] = "some random test data";
• struct dev_cgroup *skel;
• int cgroup_fd;
• cgroup_fd = cgroup_setup_and_join(TEST_CGROUP);
• if (!ASSERT_OK_FD(cgroup_fd, "cgroup switch"))

• return;
  

• skel = dev_cgroup__open_and_load();
• if (!ASSERT_OK_PTR(skel, "load program"))

• goto cleanup_cgroup;
  

• skel->links.bpf_prog1 =

• bpf_program__attach_cgroup(skel->progs.bpf_prog1, cgroup_fd);
  

• if (!ASSERT_OK_PTR(skel->links.bpf_prog1, "attach_program"))

• goto cleanup_progs;
  

• if (test__start_subtest("allow-mknod"))

• test_mknod("/dev/test_dev_cgroup_null", S_IFCHR, 1, 3, 0);
  

• if (test__start_subtest("allow-read"))

• test_read("/dev/urandom", buf, TEST_BUFFER_SIZE,
  

• 	  TEST_BUFFER_SIZE);
  

• if (test__start_subtest("allow-write"))

• test_write("/dev/null", buf, TEST_BUFFER_SIZE,
  

• 	   TEST_BUFFER_SIZE);
  

• if (test__start_subtest("deny-mknod"))

• test_mknod("/dev/test_dev_cgroup_zero", S_IFCHR, 1, 5, -EPERM);
  

• if (test__start_subtest("deny-read"))

• test_read("/dev/random", buf, TEST_BUFFER_SIZE, -EPERM);
  

• if (test__start_subtest("deny-write"))

• test_write("/dev/zero", buf, TEST_BUFFER_SIZE, -EPERM);
  

+cleanup_progs:

• dev_cgroup__destroy(skel);

+cleanup_cgroup:

• cleanup_cgroup_environment();

+}