[PATCH v5 4/9] landlock/selftests: Test LANDLOCK_ACCESS_FS_RESOLVE_UNIX

[Mickaël Salaün]

On Sun, Feb 15, 2026 at 11:51:52AM +0100, Günther Noack wrote:
> * Extract common helpers from an existing IOCTL test that
>   also uses pathname unix(7) sockets.
> * These tests use the common scoped domains fixture which is also used
>   in other Landlock scoping tests and which was used in Tingmao Wang's
>   earlier patch set in [1].
> 
> These tests exercise the cross product of the following scenarios:
> 
> * Stream connect(), Datagram connect(), Datagram sendmsg() and
>   Seqpacket connect().
> * Child-to-parent and parent-to-child communication
> * The Landlock policy configuration as listed in the scoped_domains
>   fixture.
>   * In the default variant, Landlock domains are only placed where
>     prescribed in the fixture.
>   * In the "ALL_DOMAINS" variant, Landlock domains are also placed in
>     the places where the fixture says to omit them, but with a
>     LANDLOCK_RULE_PATH_BENEATH that allows connection.
> 
> Cc: Justin Suess <utilityemal77 at gmail.com>
> Cc: Tingmao Wang <m at maowtm.org>
> Cc: Mickaël Salaün <mic at digikod.net>
> Link[1]: https://lore.kernel.org/all/53b9883648225d5a08e82d2636ab0b4fda003bc9.1767115163.git.m@maowtm.org/
> Signed-off-by: Günther Noack <gnoack3000 at gmail.com>
> ---
>  tools/testing/selftests/landlock/fs_test.c | 384 ++++++++++++++++++++-
>  1 file changed, 368 insertions(+), 16 deletions(-)
> 
> diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
> index b318627e7561..bdeff2e0e029 100644
> --- a/tools/testing/selftests/landlock/fs_test.c
> +++ b/tools/testing/selftests/landlock/fs_test.c
> @@ -4358,30 +4358,61 @@ TEST_F_FORK(layout1, named_pipe_ioctl)
>  	ASSERT_EQ(child_pid, waitpid(child_pid, NULL, 0));
>  }
>  
> +/*
> + * set_up_named_unix_server - Create a pathname unix socket
> + *
> + * If the socket type is not SOCK_DGRAM, also invoke listen(2).
> + *
> + * Return: The listening FD - it is the caller responsibility to close it.
> + */
> +static int set_up_named_unix_server(struct __test_metadata *const _metadata,
> +				    int type, const char *const path)
> +{
> +	int fd;
> +	struct sockaddr_un addr = {
> +		.sun_family = AF_UNIX,
> +	};
> +
> +	fd = socket(AF_UNIX, type, 0);
> +	ASSERT_LE(0, fd);
> +
> +	strncpy(addr.sun_path, path, sizeof(addr.sun_path));

fs_test.c: In function ‘set_up_named_unix_server’:
fs_test.c:4125:9: error: ‘strncpy’ specified bound 108 equals destination size [-Werror=stringop-truncation]
 4125 |         strncpy(addr.sun_path, path, sizeof(addr.sun_path));
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We should also ASSERT the result to make sure path's length is not too big.

> +	ASSERT_EQ(0, bind(fd, (struct sockaddr *)&addr, sizeof(addr)));
> +
> +	if (type != SOCK_DGRAM)
> +		ASSERT_EQ(0, listen(fd, 10 /* qlen */));
> +	return fd;
> +}