Re: [PATCH v1 1/2] selftests/landlock: Add tests to check undefined rule's access rights

["Günther Noack" <gnoack@google.com>]

On Mon, Nov 20, 2023 at 08:39:13PM +0100, Mickaël Salaün wrote:
> Extend two tests to make sure that we cannot add a rule with access
> rights that are undefined:
> * fs: layout1.file_and_dir_access_rights
> * net: mini.network_access_rights
> 
> The checks test all 64 bits access right values until it overflows.
> 
> Replace one ASSERT with EXPECT in layout1.file_and_dir_access_rights .
> 
> Cc: Günther Noack <gnoack@google.com>
> Cc: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
> Signed-off-by: Mickaël Salaün <mic@digikod.net>
> ---
>  tools/testing/selftests/landlock/fs_test.c  | 17 ++++++++++++-----
>  tools/testing/selftests/landlock/net_test.c | 17 ++++++++++-------
>  2 files changed, 22 insertions(+), 12 deletions(-)
> 
> diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
> index 18e1f86a6234..d77155d75de5 100644
> --- a/tools/testing/selftests/landlock/fs_test.c
> +++ b/tools/testing/selftests/landlock/fs_test.c
> @@ -548,7 +548,6 @@ TEST_F_FORK(layout1, inval)
>  TEST_F_FORK(layout1, file_and_dir_access_rights)
>  {
>  	__u64 access;
> -	int err;
>  	struct landlock_path_beneath_attr path_beneath_file = {},
>  					  path_beneath_dir = {};
>  	struct landlock_ruleset_attr ruleset_attr = {
> @@ -568,11 +567,19 @@ TEST_F_FORK(layout1, file_and_dir_access_rights)
>  		open(dir_s1d2, O_PATH | O_DIRECTORY | O_CLOEXEC);
>  	ASSERT_LE(0, path_beneath_dir.parent_fd);
>  
> -	for (access = 1; access <= ACCESS_LAST; access <<= 1) {
> +	for (access = 1; access > 0; access <<= 1) {
> +		int err;
> +
>  		path_beneath_dir.allowed_access = access;
> -		ASSERT_EQ(0, landlock_add_rule(ruleset_fd,
> -					       LANDLOCK_RULE_PATH_BENEATH,
> -					       &path_beneath_dir, 0));
> +		err = landlock_add_rule(ruleset_fd, LANDLOCK_RULE_PATH_BENEATH,
> +					&path_beneath_dir, 0);
> +		if (access <= ACCESS_LAST) {
> +			EXPECT_EQ(0, err);
> +		} else {
> +			EXPECT_EQ(-1, err);
> +			EXPECT_EQ(EINVAL, errno);
> +			continue;
> +		}

Style question: why not have two loops next to each other?  You could keep the
old loop from 1 to ACCESS_LAST and then have a separate one from ACCESS_LAST+1
onwards.  Then you would not need to put logic inside the loop; it might reduce
nesting a bit, and each loop individually might be slightly easier to grasp.

I was initially a bit confused why the other landlock_add_rule() call for the
directory doesn't need the same change. That is clear to me after looking at the
code a few seconds longer, but it might be slightly simpler with two separate
loops.

But this is a minor nit.

Reviewed-by: Günther Noack <gnoack@google.com>

Thanks!
—Günther