[PATCH v5 3/9] samples/landlock: Add support for named UNIX domain socket restrictions

[Mickaël Salaün]

On Sun, Feb 15, 2026 at 11:51:51AM +0100, Günther Noack wrote:
> The access right for UNIX domain socket lookups is grouped with the
> read-write rights in the sample tool.  Rationale: In the general case,
> any operations are possible through a UNIX domain socket, including
> data-mutating operations.
> 
> Cc: Justin Suess <utilityemal77 at gmail.com>
> Cc: Mickaël Salaün <mic at digikod.net>
> Signed-off-by: Günther Noack <gnoack3000 at gmail.com>
> ---
>  samples/landlock/sandboxer.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
> index e7af02f98208..0bbbc5c9ead6 100644
> --- a/samples/landlock/sandboxer.c
> +++ b/samples/landlock/sandboxer.c
> @@ -111,7 +111,8 @@ static int parse_path(char *env_path, const char ***const path_list)
>  	LANDLOCK_ACCESS_FS_WRITE_FILE | \
>  	LANDLOCK_ACCESS_FS_READ_FILE | \
>  	LANDLOCK_ACCESS_FS_TRUNCATE | \
> -	LANDLOCK_ACCESS_FS_IOCTL_DEV)
> +	LANDLOCK_ACCESS_FS_IOCTL_DEV | \
> +	LANDLOCK_ACCESS_FS_RESOLVE_UNIX)
>  
>  /* clang-format on */
>  
> @@ -295,11 +296,12 @@ static bool check_ruleset_scope(const char *const env_var,
>  	LANDLOCK_ACCESS_FS_MAKE_SYM | \
>  	LANDLOCK_ACCESS_FS_REFER | \
>  	LANDLOCK_ACCESS_FS_TRUNCATE | \
> -	LANDLOCK_ACCESS_FS_IOCTL_DEV)
> +	LANDLOCK_ACCESS_FS_IOCTL_DEV | \
> +	LANDLOCK_ACCESS_FS_RESOLVE_UNIX)
>  
>  /* clang-format on */
>  
> -#define LANDLOCK_ABI_LAST 7
> +#define LANDLOCK_ABI_LAST 9
>  
>  #define XSTR(s) #s
>  #define STR(s) XSTR(s)
> @@ -444,6 +446,13 @@ int main(const int argc, char *const argv[], char *const *const envp)
>  			"provided by ABI version %d (instead of %d).\n",
>  			LANDLOCK_ABI_LAST, abi);
>  		__attribute__((fallthrough));
> +	case 7:
> +		__attribute__((fallthrough));

The current code should print the hint when ABI <= 7.  Please send a
dedicated patch to fix the TSYNC-related changes.

> +	case 8:
> +		/* Removes LANDLOCK_ACCESS_FS_RESOLVE_UNIX for ABI < 9 */
> +		ruleset_attr.handled_access_fs &=
> +			~LANDLOCK_ACCESS_FS_RESOLVE_UNIX;
> +		__attribute__((fallthrough));
>  	case LANDLOCK_ABI_LAST:
>  		break;
>  	default:
> -- 
> 2.52.0
> 
>