[PATCH v2 3/5] samples/landlock: Add support for named UNIX domain socket restrictions

["Günther Noack" <gnoack3000@gmail.com>]

The access rights for UNIX domain socket lookups are 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@gmail.com>
Cc: Mickaël Salaün <mic@digikod.net>
Signed-off-by: Günther Noack <gnoack3000@gmail.com>
---
 samples/landlock/sandboxer.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
index e7af02f98208..f7e73ba8910c 100644
--- a/samples/landlock/sandboxer.c
+++ b/samples/landlock/sandboxer.c
@@ -295,11 +295,14 @@ 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_STREAM | \
+	LANDLOCK_ACCESS_FS_RESOLVE_UNIX_DGRAM | \
+	LANDLOCK_ACCESS_FS_RESOLVE_UNIX_SEQPACKET)
 
 /* clang-format on */
 
-#define LANDLOCK_ABI_LAST 7
+#define LANDLOCK_ABI_LAST 8
 
 #define XSTR(s) #s
 #define STR(s) XSTR(s)
@@ -444,6 +447,17 @@ 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:
+		/*
+		 * Removes LANDLOCK_ACCESS_FS_RESOLVE_UNIX_STREAM,
+		 * LANDLOCK_ACCESS_FS_RESOLVE_UNIX_DGRAM and
+		 * LANDLOCK_ACCESS_FS_RESOLVE_UNIX_SEQPACKET for ABI < 8
+		 */
+		ruleset_attr.handled_access_fs &=
+			~(LANDLOCK_ACCESS_FS_RESOLVE_UNIX_STREAM |
+			  LANDLOCK_ACCESS_FS_RESOLVE_UNIX_DGRAM |
+			  LANDLOCK_ACCESS_FS_RESOLVE_UNIX_SEQPACKET);
+		__attribute__((fallthrough));
 	case LANDLOCK_ABI_LAST:
 		break;
 	default:
-- 
2.52.0