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>
---
 tools/testing/selftests/bpf/.gitignore             |   1 -
 tools/testing/selftests/bpf/Makefile               |   2 -
 .../testing/selftests/bpf/prog_tests/cgroup_dev.c  | 120 +++++++++++++++++++++
 tools/testing/selftests/bpf/test_dev_cgroup.c      |  85 ---------------
 4 files changed, 120 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..5112b99213ad
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/cgroup_dev.c
@@ -0,0 +1,120 @@
+// 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 should_fail)
+{
+	int ret;
+
+	unlink(path);
+	ret = mknod(path, mode, makedev(dev_major, dev_minor));
+	if (should_fail)
+		ASSERT_ERR(ret, "mknod");
+	else
+		ASSERT_OK(ret, "mknod");
+	unlink(path);
+}
+
+static void test_read(const char *path, int should_fail)
+{
+	char buf[TEST_BUFFER_SIZE];
+	int ret, fd;
+
+	fd = open(path, O_RDONLY);
+
+	/* A bare open on unauthorized device should fail */
+	if (should_fail) {
+		ASSERT_ERR(fd, "open file for read");
+		if (fd)
+			close(fd);
+		return;
+	}
+
+	if (!ASSERT_OK_FD(fd, "open file for read"))
+		return;
+
+	ret = read(fd, buf, TEST_BUFFER_SIZE);
+	if (should_fail)
+		ASSERT_ERR(ret, "read");
+	else
+		ASSERT_EQ(ret, TEST_BUFFER_SIZE, "read");
+
+	close(fd);
+}
+
+static void test_write(const char *path, int should_fail)
+{
+	char buf[] = "some random test data";
+	int ret, fd;
+
+	fd = open(path, O_WRONLY);
+
+	/* A bare open on unauthorized device should fail */
+	if (should_fail) {
+		ASSERT_ERR(fd, "open file for write");
+		if (fd)
+			close(fd);
+		return;
+	}
+
+	if (!ASSERT_OK_FD(fd, "open file for write"))
+		return;
+
+	ret = write(fd, buf, sizeof(buf));
+	if (should_fail)
+		ASSERT_ERR(ret, "write");
+	else
+		ASSERT_EQ(ret, sizeof(buf), "write");
+
+	close(fd);
+}
+
+void test_cgroup_dev(void)
+{
+	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"))
+		goto cleanup_progs;
+
+	if (test__start_subtest("deny-mknod"))
+		test_mknod("/dev/test_dev_cgroup_zero", S_IFCHR, 1, 5, 1);
+
+	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", 0);
+
+	if (test__start_subtest("allow-write"))
+		test_write("/dev/null", 0);
+
+	if (test__start_subtest("deny-read"))
+		test_read("/dev/random", 1);
+
+	if (test__start_subtest("deny-write"))
+		test_write("/dev/zero", 1);
+
+cleanup_progs:
+	dev_cgroup__destroy(skel);
+cleanup_cgroup:
+	cleanup_cgroup_environment();
+}
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 33f544f0005a..000000000000
--- 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/null and /dev/urandom are allowed,
-	 * everything else is forbidden.
-	 */
-	assert(system("rm -f /tmp/test_dev_cgroup_zero") == 0);
-	assert(system("mknod /tmp/test_dev_cgroup_zero c 1 5"));
-	assert(system("rm -f /tmp/test_dev_cgroup_zero") == 0);
-
-	/* /dev/null is whitelisted */
-	assert(system("rm -f /tmp/test_dev_cgroup_null") == 0);
-	assert(system("mknod /tmp/test_dev_cgroup_null c 1 3") == 0);
-	assert(system("rm -f /tmp/test_dev_cgroup_null") == 0);
-
-	assert(system("dd if=/dev/urandom of=/dev/null 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/null count=64"));
-
-	error = 0;
-	printf("test_dev_cgroup:PASS\n");
-
-err:
-	cleanup_cgroup_environment();
-
-out:
-	return error;
-}

-- 
2.45.2

On 07/25, 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>
> ---
>  tools/testing/selftests/bpf/.gitignore             |   1 -
>  tools/testing/selftests/bpf/Makefile               |   2 -
>  .../testing/selftests/bpf/prog_tests/cgroup_dev.c  | 120 +++++++++++++++++++++
>  tools/testing/selftests/bpf/test_dev_cgroup.c      |  85 ---------------
>  4 files changed, 120 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..5112b99213ad
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/cgroup_dev.c
> @@ -0,0 +1,120 @@
> +// 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 should_fail)
> +{
> +	int ret;
> +
> +	unlink(path);
> +	ret = mknod(path, mode, makedev(dev_major, dev_minor));

[..]

> +	if (should_fail)
> +		ASSERT_ERR(ret, "mknod");
> +	else
> +		ASSERT_OK(ret, "mknod");

Optional: might be easier to use something like expected_ret instead
of should_fail and then do:

ASSERT_EQ(ret, expected_ret)

I see this part being copy-pasted in a bunch of places below.

> +	unlink(path);
> +}
> +
> +static void test_read(const char *path, int should_fail)
> +{
> +	char buf[TEST_BUFFER_SIZE];
> +	int ret, fd;
> +
> +	fd = open(path, O_RDONLY);
> +
> +	/* A bare open on unauthorized device should fail */
> +	if (should_fail) {
> +		ASSERT_ERR(fd, "open file for read");

[..]

> +		if (fd)
> +			close(fd);

nit: should this be 'if (fd >= 0)'? I'm assuming the intention is to
avoid close(-1)?

> +		return;
> +	}
> +
> +	if (!ASSERT_OK_FD(fd, "open file for read"))
> +		return;
> +
> +	ret = read(fd, buf, TEST_BUFFER_SIZE);
> +	if (should_fail)
> +		ASSERT_ERR(ret, "read");
> +	else
> +		ASSERT_EQ(ret, TEST_BUFFER_SIZE, "read");
> +
> +	close(fd);
> +}
> +
> +static void test_write(const char *path, int should_fail)
> +{
> +	char buf[] = "some random test data";
> +	int ret, fd;
> +
> +	fd = open(path, O_WRONLY);
> +
> +	/* A bare open on unauthorized device should fail */
> +	if (should_fail) {
> +		ASSERT_ERR(fd, "open file for write");
> +		if (fd)
> +			close(fd);

Same 'if (fd >= 0)'

Hello Stanislas, thanks for the review

On 7/27/24 00:48, Stanislav Fomichev wrote:
> On 07/25, Alexis Lothoré (eBPF Foundation) wrote:

[...]

>> +	if (should_fail)
>> +		ASSERT_ERR(ret, "mknod");
>> +	else
>> +		ASSERT_OK(ret, "mknod");
> 
> Optional: might be easier to use something like expected_ret instead
> of should_fail and then do:
> 
> ASSERT_EQ(ret, expected_ret)

Yes, you are right. I initially went with a version relying on system() to
perform the mknods/dd calls, which could return different errors codes so I used
this should_fail. But while debugging some issues in CI with this series, I
realized that the needed commands are basic enough to be replaced with direct
library calls and I forgot to update this part, which can now assert an exact
return value. I will update this accordingly.

> I see this part being copy-pasted in a bunch of places below.
> 
>> +	unlink(path);
>> +}
>> +
>> +static void test_read(const char *path, int should_fail)
>> +{
>> +	char buf[TEST_BUFFER_SIZE];
>> +	int ret, fd;
>> +
>> +	fd = open(path, O_RDONLY);
>> +
>> +	/* A bare open on unauthorized device should fail */
>> +	if (should_fail) {
>> +		ASSERT_ERR(fd, "open file for read");
> 
> [..]
> 
>> +		if (fd)
>> +			close(fd);
> 
> nit: should this be 'if (fd >= 0)'? I'm assuming the intention is to
> avoid close(-1)?

Right as well, I'll fix it (here and below) in v2

Thanks,

Alexis

-- 
Alexis Lothoré, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com