[PATCH v5] selftests/landlock: Skip overlayfs tests not supported

[Mickaël Salaün]

As discussed for the v4, the next version of this patch needs a 
TEST_F_FORK() fix.

Please add a link to the previous patch (lore.kernel.org) for each new 
version.


On 24/08/2022 03:58, jeffxu at chromium.org wrote:
> From: Jeff Xu <jeffxu at chromium.org>
> 
> overlayfs can be disabled in the kernel configuration (which is the case
> for chromeOS), causing related tests to fail.  Skip such tests when an
> overlayfs mount operation failed because the running kernel doesn't
> support this file system.
> 
> Signed-off-by: Jeff Xu <jeffxu at chromium.org>
> Reviewed-by: Guenter Roeck <groeck at chromium.org>
> ---
>   tools/testing/selftests/landlock/fs_test.c | 54 ++++++++++++++++++++--
>   1 file changed, 51 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
> index 21a2ce8fa739..645304d9fe98 100644
> --- a/tools/testing/selftests/landlock/fs_test.c
> +++ b/tools/testing/selftests/landlock/fs_test.c
> @@ -11,6 +11,7 @@
>   #include <fcntl.h>
>   #include <linux/landlock.h>
>   #include <sched.h>
> +#include <stdio.h>
>   #include <string.h>
>   #include <sys/capability.h>
>   #include <sys/mount.h>
> @@ -169,6 +170,42 @@ static int remove_path(const char *const path)
>   	return err;
>   }
>   
> +static bool fgrep(FILE *file, const char *str)
> +{
> +	char line[32];
> +	int str_len = strlen(str);
> +
> +	while (!feof(file)) {
> +		if (!fgets(line, sizeof(line), file))
> +			break;
> +		if (strncmp(line, str, str_len))
> +			continue;
> +
> +		return true;
> +	}
> +
> +	return false;
> +}
> +
> +static bool supports_overlayfs(void)
> +{
> +	bool ret;
> +	FILE *file = fopen("/proc/filesystems", "r");
> +
> +	/*
> +	 * A failed attempt to open /proc/filesystems
> +	 * implies that the file system is supported (default
> +	 * behavior). This can help detect such unattended issue
> +	 * (which should not happen)."
> +	 */
> +	if (!file)
> +		return true;
> +
> +	ret = fgrep(file, "nodev\toverlay\n");
> +	fclose(file);
> +	return ret;
> +}
> +
>   static void prepare_layout(struct __test_metadata *const _metadata)
>   {
>   	disable_caps(_metadata);
> @@ -3404,6 +3441,8 @@ FIXTURE(layout2_overlay) {};
>   
>   FIXTURE_SETUP(layout2_overlay)
>   {
> +	int ret, err;
> +
>   	prepare_layout(_metadata);
>   
>   	create_directory(_metadata, LOWER_BASE);
> @@ -3431,11 +3470,20 @@ FIXTURE_SETUP(layout2_overlay)
>   	create_directory(_metadata, MERGE_DATA);
>   	set_cap(_metadata, CAP_SYS_ADMIN);
>   	set_cap(_metadata, CAP_DAC_OVERRIDE);
> -	ASSERT_EQ(0, mount("overlay", MERGE_DATA, "overlay", 0,
> -			   "lowerdir=" LOWER_DATA ",upperdir=" UPPER_DATA
> -			   ",workdir=" UPPER_WORK));
> +
> +	ret = mount("overlay", MERGE_DATA, "overlay", 0,
> +		   "lowerdir=" LOWER_DATA ",upperdir=" UPPER_DATA
> +		   ",workdir=" UPPER_WORK);
> +	err = errno;
>   	clear_cap(_metadata, CAP_DAC_OVERRIDE);
>   	clear_cap(_metadata, CAP_SYS_ADMIN);
> +
> +	if (ret == -1) {
> +		ASSERT_EQ(ENODEV, err);
> +		ASSERT_FALSE(supports_overlayfs());
> +		SKIP(return, "overlayfs is not supported");
> +	}
> +	ASSERT_EQ(0, ret);
>   }
>   
>   FIXTURE_TEARDOWN(layout2_overlay)
> 
> base-commit: 50cd95ac46548429e5bba7ca75cc97d11a697947