linux-kernel - Re: [PATCH 2/2] selftests: landlock: skip all tests without landlock syscall

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Date:   Thu, 17 Aug 2023 19:26:25 +0200
From:   Mickaël Salaün <mic@...ikod.net>
To:     Andre Przywara <andre.przywara@....com>
Cc:     Shuah Khan <shuah@...nel.org>,
        linux-security-module@...r.kernel.org,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
        Günther Noack <gnoack@...gle.com>
Subject: Re: [PATCH 2/2] selftests: landlock: skip all tests without landlock
 syscall

On Wed, Aug 09, 2023 at 06:04:35PM +0100, Andre Przywara wrote:
> "landlock" is a relatively new syscall, and most defconfigs do not enable
> it (yet). On systems without this syscall available, the selftests fail
> at the moment, instead of being skipped.
> 
> Check the availability of the landlock system call before executing each
> test, and skip the rest of the tests if we get an ENOSYS back.
> 
> Signed-off-by: Andre Przywara <andre.przywara@....com>
> ---
>  tools/testing/selftests/landlock/base_test.c | 27 ++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/tools/testing/selftests/landlock/base_test.c b/tools/testing/selftests/landlock/base_test.c
> index 1e3b6de57e80e..c539cec775fba 100644
> --- a/tools/testing/selftests/landlock/base_test.c
> +++ b/tools/testing/selftests/landlock/base_test.c
> @@ -21,12 +21,20 @@
>  #define O_PATH 010000000
>  #endif
>  
> +static bool has_syscall(void)
> +{
> +	return landlock_create_ruleset(NULL, 0, 0) == -1 && errno != ENOSYS;
> +}

We could replace most TEST*(name) macros with
TEST*_LANDLOCK(name, minimal_abi_version).

These TEST*_LANDLOCK() macros would simply prepend a header like this:

const int abi_version = landlock_create_ruleset(NULL, 0,
	LANDLOCK_CREATE_RULESET_VERSION);
if (abi_version < minimal_abi_version)
	SKIP(return, "only supported since Landlock ABI %d (instead of
		%d)", minimal_abi_version, abi_version);

These helpers need to be defined in common.h to be easily usable everywhere.

> +
>  TEST(inconsistent_attr)
>  {
>  	const long page_size = sysconf(_SC_PAGESIZE);
>  	char *const buf = malloc(page_size + 1);
>  	struct landlock_ruleset_attr *const ruleset_attr = (void *)buf;
>  
> +	if (!has_syscall())
> +		SKIP(return, "landlock syscall not available");
> +
>  	ASSERT_NE(NULL, buf);
>  
>  	/* Checks copy_from_user(). */
> @@ -75,6 +83,10 @@ TEST(abi_version)
>  	const struct landlock_ruleset_attr ruleset_attr = {
>  		.handled_access_fs = LANDLOCK_ACCESS_FS_READ_FILE,
>  	};
> +
> +	if (!has_syscall())
> +		SKIP(return, "landlock syscall not available");
> +
>  	ASSERT_NE(0, landlock_create_ruleset(NULL, 0,
>  					     LANDLOCK_CREATE_RULESET_VERSION));
>  
> @@ -107,6 +119,9 @@ TEST(create_ruleset_checks_ordering)
>  		.handled_access_fs = LANDLOCK_ACCESS_FS_READ_FILE,
>  	};
>  
> +	if (!has_syscall())
> +		SKIP(return, "landlock syscall not available");
> +
>  	/* Checks priority for invalid flags. */
>  	ASSERT_EQ(-1, landlock_create_ruleset(NULL, 0, invalid_flag));
>  	ASSERT_EQ(EINVAL, errno);
> @@ -153,6 +168,9 @@ TEST(add_rule_checks_ordering)
>  	const int ruleset_fd =
>  		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
>  
> +	if (!has_syscall())
> +		SKIP(return, "landlock syscall not available");
> +
>  	ASSERT_LE(0, ruleset_fd);
>  
>  	/* Checks invalid flags. */
> @@ -200,6 +218,9 @@ TEST(restrict_self_checks_ordering)
>  	const int ruleset_fd =
>  		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
>  
> +	if (!has_syscall())
> +		SKIP(return, "landlock syscall not available");
> +
>  	ASSERT_LE(0, ruleset_fd);
>  	path_beneath_attr.parent_fd =
>  		open("/tmp", O_PATH | O_NOFOLLOW | O_DIRECTORY | O_CLOEXEC);
> @@ -240,6 +261,9 @@ TEST(ruleset_fd_io)
>  	int ruleset_fd;
>  	char buf;
>  
> +	if (!has_syscall())
> +		SKIP(return, "landlock syscall not available");
> +
>  	drop_caps(_metadata);
>  	ruleset_fd =
>  		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
> @@ -267,6 +291,9 @@ TEST(ruleset_fd_transfer)
>  	pid_t child;
>  	int status;
>  
> +	if (!has_syscall())
> +		SKIP(return, "landlock syscall not available");
> +
>  	drop_caps(_metadata);
>  
>  	/* Creates a test ruleset with a simple rule. */
> -- 
> 2.25.1
>