Re: [PATCH bpf-next v2 2/3] selftests/bpf: convert test_dev_cgroup to test_progs

On 29/07/2024 09:20, Alexis Lothoré (eBPF Foundation) wrote:

test_dev_cgroup is defined as a standalone test program, and so is not executed in CI.

Convert it to test_progs framework so it is tested automatically in CI, and remove the old test. In order to be able to run it in test_progs, /dev/null must remain usable, so change the new test to test operations on devices 1:3 as valid, and operations on devices 1:5 (/dev/zero) as invalid.

Signed-off-by: Alexis Lothoré (eBPF Foundation) alexis.lothore@bootlin.com

A few small suggestions but looks great!

Reviewed-by: Alan Maguire alan.maguire@oracle.com

---

Changes in v2:

• pass expected return code to subtest function instead of boolean pass/not pass
• also pass buffer and buffer size for read/write subtests
• fix faulty fd check on read/write tests expected to fail

---

tools/testing/selftests/bpf/.gitignore | 1 - tools/testing/selftests/bpf/Makefile | 2 - .../testing/selftests/bpf/prog_tests/cgroup_dev.c | 110 +++++++++++++++++++++ tools/testing/selftests/bpf/test_dev_cgroup.c | 85 ---------------- 4 files changed, 110 insertions(+), 88 deletions(-)

diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore index 4e4aae8aa7ec..8f14d8faeb0b 100644 --- a/tools/testing/selftests/bpf/.gitignore +++ b/tools/testing/selftests/bpf/.gitignore @@ -9,7 +9,6 @@ test_lpm_map test_tag FEATURE-DUMP.libbpf fixdep -test_dev_cgroup /test_progs /test_progs-no_alu32 /test_progs-bpf_gcc diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index aeada478e37a..2a9ba2246f80 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -69,7 +69,6 @@ endif # Order correspond to 'make run_tests' order TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \

• test_dev_cgroup \ test_sock test_sockmap get_cgroup_id_user \ test_cgroup_storage \ test_tcpnotify_user test_sysctl \

@@ -295,7 +294,6 @@ JSON_WRITER := $(OUTPUT)/json_writer.o CAP_HELPERS := $(OUTPUT)/cap_helpers.o NETWORK_HELPERS := $(OUTPUT)/network_helpers.o -$(OUTPUT)/test_dev_cgroup: $(CGROUP_HELPERS) $(TESTING_HELPERS) $(OUTPUT)/test_skb_cgroup_id_user: $(CGROUP_HELPERS) $(TESTING_HELPERS) $(OUTPUT)/test_sock: $(CGROUP_HELPERS) $(TESTING_HELPERS) $(OUTPUT)/test_sockmap: $(CGROUP_HELPERS) $(TESTING_HELPERS) diff --git a/tools/testing/selftests/bpf/prog_tests/cgroup_dev.c b/tools/testing/selftests/bpf/prog_tests/cgroup_dev.c new file mode 100644 index 000000000000..af0b70086c21 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/cgroup_dev.c @@ -0,0 +1,110 @@ +// SPDX-License-Identifier: GPL-2.0

+#include <sys/stat.h> +#include <sys/sysmacros.h> +#include "test_progs.h" +#include "cgroup_helpers.h" +#include "dev_cgroup.skel.h"

+#define TEST_CGROUP "/test-bpf-based-device-cgroup/" +#define TEST_BUFFER_SIZE 64

+static void test_mknod(const char *path, mode_t mode, int dev_major,

•        int dev_minor, int expected_ret)
  

+{

• int ret;
• unlink(path);
• ret = mknod(path, mode, makedev(dev_major, dev_minor));
• ASSERT_EQ(ret, expected_ret, "mknod");

no need to unlink unless "if (!ret)"

• unlink(path);

+}

+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");
  

• 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;
  

• if (!ASSERT_OK(bpf_prog_attach(bpf_program__fd(skel->progs.bpf_prog1),

• 		       cgroup_fd, BPF_CGROUP_DEVICE, 0),
  

•        "attach_program"))
  

I'd suggest using bpf_program__attach_cgroup() here as you can assign the link in the skeleton; see prog_tests/cgroup_v1v2.c.

• goto cleanup_progs;
  

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

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

nit: group with other deny subtests.

• 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);
  

Nit: should we have a separate garbage buffer for the successful /dev/urandom read? We're not validating buffer contents anywhere but we will overwrite our test string I think and it'll end up non-null terminated.

Alan