Re: [PATCH bpf-next v2] selftests/bpf: Move test_dev_cgroup to prog_tests

[Muhammad Usama Anjum <usama.anjum@collabora.com>]

On 2/21/24 2:22 PM, Muhammad Usama Anjum wrote:
> Move test_dev_cgroup.c to prog_tests/dev_cgroup.c to be able to run it
> with test_progs. Replace dev_cgroup.bpf.o with skel header file,
> dev_cgroup.skel.h and load program from it accourdingly.
> 
>   ./test_progs -t test_dev_cgroup
>   mknod: /tmp/test_dev_cgroup_null: Operation not permitted
>   64+0 records in
>   64+0 records out
>   32768 bytes (33 kB, 32 KiB) copied, 0.000856684 s, 38.2 MB/s
>   dd: failed to open '/dev/full': Operation not permitted
>   dd: failed to open '/dev/random': Operation not permitted
>   #365     test_dev_cgroup:OK
>   Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED
> 
> Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
> ---
> I've tested the patch with vmtest.sh on bpf-next/for-next and linux
> next. It is passing on both. Not sure why it was failed on BPFCI.
> Test run with vmtest.h:
> sudo LDLIBS=-static PKG_CONFIG='pkg-config --static' ./vmtest.sh ./test_progs -t dev_cgroup
> ./test_progs -t dev_cgroup
> mknod: /tmp/test_dev_cgroup_null: Operation not permitted
> 64+0 records in
> 64+0 records out
> 32768 bytes (33 kB, 32 KiB) copied, 0.000403432 s, 81.2 MB/s
> dd: failed to open '/dev/full': Operation not permitted
> dd: failed to open '/dev/random': Operation not permitted
>  #69      dev_cgroup:OK
> Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED
Locally this test passes, but fails on BPFCI:
https://github.com/kernel-patches/bpf/actions/runs/7986809998/job/21808178301#step:5:9744

> 
> Changes since v1:
> - Rename file from test_dev_cgroup.c to dev_cgroup.c
> - Use ASSERT_* in-place of CHECK
> ---
>  .../selftests/bpf/prog_tests/dev_cgroup.c     | 58 +++++++++++++
>  tools/testing/selftests/bpf/test_dev_cgroup.c | 85 -------------------
>  2 files changed, 58 insertions(+), 85 deletions(-)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/dev_cgroup.c
>  delete mode 100644 tools/testing/selftests/bpf/test_dev_cgroup.c
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/dev_cgroup.c b/tools/testing/selftests/bpf/prog_tests/dev_cgroup.c
> new file mode 100644
> index 0000000000000..980b015a116ff
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/dev_cgroup.c
> @@ -0,0 +1,58 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright (c) 2017 Facebook
> + */
> +
> +#include <test_progs.h>
> +#include <time.h>
> +#include "cgroup_helpers.h"
> +#include "dev_cgroup.skel.h"
> +
> +#define TEST_CGROUP "/test-bpf-based-device-cgroup/"
> +
> +void test_dev_cgroup(void)
> +{
> +	struct dev_cgroup *skel;
> +	int cgroup_fd, err;
> +	__u32 prog_cnt;
> +
> +	skel = dev_cgroup__open_and_load();
> +	if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
> +		goto cleanup;
> +
> +	cgroup_fd = cgroup_setup_and_join(TEST_CGROUP);
> +	if (!ASSERT_GT(cgroup_fd, 0, "cgroup_setup_and_join"))
> +		goto cleanup;
> +
> +	err = bpf_prog_attach(bpf_program__fd(skel->progs.bpf_prog1), cgroup_fd,
> +			      BPF_CGROUP_DEVICE, 0);
> +	if (!ASSERT_EQ(err, 0, "bpf_attach"))
> +		goto cleanup;
> +
> +	err = bpf_prog_query(cgroup_fd, BPF_CGROUP_DEVICE, 0, NULL, NULL, &prog_cnt);
> +	if (!ASSERT_EQ(err, 0, "bpf_query") || (!ASSERT_EQ(prog_cnt, 1, "bpf_query")))
> +		goto cleanup;
> +
> +	/* All operations with /dev/zero and /dev/urandom are allowed,
> +	 * everything else is forbidden.
> +	 */
> +	ASSERT_EQ(system("rm -f /tmp/test_dev_cgroup_null"), 0, "rm");
> +	ASSERT_NEQ(system("mknod /tmp/test_dev_cgroup_null c 1 3"), 0, "mknod");
> +	ASSERT_EQ(system("rm -f /tmp/test_dev_cgroup_null"), 0, "rm");
> +
> +	/* /dev/zero is whitelisted */
> +	ASSERT_EQ(system("rm -f /tmp/test_dev_cgroup_zero"), 0, "rm");
> +	ASSERT_EQ(system("mknod /tmp/test_dev_cgroup_zero c 1 5"), 0, "mknod");
Access to major number 1 and minor number 5 is allowed. The return code of
0 is expected, but on CI we are getting 256 which indicates error. mknod
help page mentions the same:

> An exit status of zero indicates success, and a nonzero value indicates
failure.


> +	ASSERT_EQ(system("rm -f /tmp/test_dev_cgroup_zero"), 0, "rm");
> +
> +	ASSERT_EQ(system("dd if=/dev/urandom of=/dev/zero count=64"), 0, "dd");
> +
> +	/* src is allowed, target is forbidden */
> +	ASSERT_NEQ(system("dd if=/dev/urandom of=/dev/full count=64"), 0, "dd");
> +
> +	/* src is forbidden, target is allowed */
> +	ASSERT_NEQ(system("dd if=/dev/random of=/dev/zero count=64"), 0, "dd");
> +
> +cleanup:
> +	cleanup_cgroup_environment();
> +	dev_cgroup__destroy(skel);
> +}
> diff --git a/tools/testing/selftests/bpf/test_dev_cgroup.c b/tools/testing/selftests/bpf/test_dev_cgroup.c
> deleted file mode 100644
> index adeaf63cb6fa3..0000000000000
> --- a/tools/testing/selftests/bpf/test_dev_cgroup.c
> +++ /dev/null
> @@ -1,85 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0-only
> -/* Copyright (c) 2017 Facebook
> - */
> -
> -#include <stdio.h>
> -#include <stdlib.h>
> -#include <string.h>
> -#include <errno.h>
> -#include <assert.h>
> -#include <sys/time.h>
> -
> -#include <linux/bpf.h>
> -#include <bpf/bpf.h>
> -#include <bpf/libbpf.h>
> -
> -#include "cgroup_helpers.h"
> -#include "testing_helpers.h"
> -
> -#define DEV_CGROUP_PROG "./dev_cgroup.bpf.o"
> -
> -#define TEST_CGROUP "/test-bpf-based-device-cgroup/"
> -
> -int main(int argc, char **argv)
> -{
> -	struct bpf_object *obj;
> -	int error = EXIT_FAILURE;
> -	int prog_fd, cgroup_fd;
> -	__u32 prog_cnt;
> -
> -	/* Use libbpf 1.0 API mode */
> -	libbpf_set_strict_mode(LIBBPF_STRICT_ALL);
> -
> -	if (bpf_prog_test_load(DEV_CGROUP_PROG, BPF_PROG_TYPE_CGROUP_DEVICE,
> -			  &obj, &prog_fd)) {
> -		printf("Failed to load DEV_CGROUP program\n");
> -		goto out;
> -	}
> -
> -	cgroup_fd = cgroup_setup_and_join(TEST_CGROUP);
> -	if (cgroup_fd < 0) {
> -		printf("Failed to create test cgroup\n");
> -		goto out;
> -	}
> -
> -	/* Attach bpf program */
> -	if (bpf_prog_attach(prog_fd, cgroup_fd, BPF_CGROUP_DEVICE, 0)) {
> -		printf("Failed to attach DEV_CGROUP program");
> -		goto err;
> -	}
> -
> -	if (bpf_prog_query(cgroup_fd, BPF_CGROUP_DEVICE, 0, NULL, NULL,
> -			   &prog_cnt)) {
> -		printf("Failed to query attached programs");
> -		goto err;
> -	}
> -
> -	/* All operations with /dev/zero and and /dev/urandom are allowed,
> -	 * everything else is forbidden.
> -	 */
> -	assert(system("rm -f /tmp/test_dev_cgroup_null") == 0);
> -	assert(system("mknod /tmp/test_dev_cgroup_null c 1 3"));
> -	assert(system("rm -f /tmp/test_dev_cgroup_null") == 0);
> -
> -	/* /dev/zero is whitelisted */
> -	assert(system("rm -f /tmp/test_dev_cgroup_zero") == 0);
> -	assert(system("mknod /tmp/test_dev_cgroup_zero c 1 5") == 0);
> -	assert(system("rm -f /tmp/test_dev_cgroup_zero") == 0);
> -
> -	assert(system("dd if=/dev/urandom of=/dev/zero count=64") == 0);
> -
> -	/* src is allowed, target is forbidden */
> -	assert(system("dd if=/dev/urandom of=/dev/full count=64"));
> -
> -	/* src is forbidden, target is allowed */
> -	assert(system("dd if=/dev/random of=/dev/zero count=64"));
> -
> -	error = 0;
> -	printf("test_dev_cgroup:PASS\n");
> -
> -err:
> -	cleanup_cgroup_environment();
> -
> -out:
> -	return error;
> -}

-- 
BR,
Muhammad Usama Anjum