samples/landlock: Add FS quiet flag support to sandboxer

Signed-off-by: Tingmao Wang <[email protected]>

Author: micromaomao

samples/landlock/sandboxer.c

@@ -58,6 +58,7 @@ static inline int landlock_restrict_self(const int ruleset_fd,
 
 #define ENV_FS_RO_NAME "LL_FS_RO"
 #define ENV_FS_RW_NAME "LL_FS_RW"
+#define ENV_FS_QUIET_NAME "LL_FS_QUIET"
 #define ENV_TCP_BIND_NAME "LL_TCP_BIND"
 #define ENV_TCP_CONNECT_NAME "LL_TCP_CONNECT"
 #define ENV_SCOPED_NAME "LL_SCOPED"
@@ -116,7 +117,7 @@ static int parse_path(char *env_path, const char ***const path_list)
 /* clang-format on */
 
 static int populate_ruleset_fs(const char *const env_var, const int ruleset_fd,
-			       const __u64 allowed_access)
+			       const __u64 allowed_access, bool quiet)
 {
 	int num_paths, i, ret = 1;
 	char *env_path_name;
@@ -166,7 +167,8 @@ static int populate_ruleset_fs(const char *const env_var, const int ruleset_fd,
 		if (!S_ISDIR(statbuf.st_mode))
 			path_beneath.allowed_access &= ACCESS_FILE;
 		if (landlock_add_rule(ruleset_fd, LANDLOCK_RULE_PATH_BENEATH,
-				      &path_beneath, 0)) {
+				      &path_beneath,
+				      quiet ? LANDLOCK_ADD_RULE_QUIET : 0)) {
 			fprintf(stderr,
 				"Failed to update the ruleset with \"%s\": %s\n",
 				path_list[i], strerror(errno));
@@ -328,6 +330,7 @@ static const char help[] =
 	"\n"
 	"A sandboxer should not log denied access requests to avoid spamming logs, "
 	"but to test audit we can set " ENV_FORCE_LOG_NAME "=1\n"
+	ENV_FS_QUIET_NAME " can then be used to make access to some denied paths not trigger audit logging.\n"
 	"\n"
 	"Example:\n"
 	ENV_FS_RO_NAME "=\"${PATH}:/lib:/usr:/proc:/etc:/dev/urandom\" "
@@ -497,12 +500,21 @@ int main(const int argc, char *const argv[], char *const *const envp)
 		return 1;
 	}
 
-	if (populate_ruleset_fs(ENV_FS_RO_NAME, ruleset_fd, access_fs_ro)) {
+	if (populate_ruleset_fs(ENV_FS_RO_NAME, ruleset_fd, access_fs_ro,
+				false)) {
 		goto err_close_ruleset;
 	}
-	if (populate_ruleset_fs(ENV_FS_RW_NAME, ruleset_fd, access_fs_rw)) {
+	if (populate_ruleset_fs(ENV_FS_RW_NAME, ruleset_fd, access_fs_rw,
+				false)) {
 		goto err_close_ruleset;
 	}
+	/* Don't require this env to be present */
+	if (getenv(ENV_FS_QUIET_NAME)) {
+		if (populate_ruleset_fs(ENV_FS_QUIET_NAME, ruleset_fd, 0,
+					true)) {
+			goto err_close_ruleset;
+		}
+	}
 
 	if (populate_ruleset_net(ENV_TCP_BIND_NAME, ruleset_fd,
 				 LANDLOCK_ACCESS_NET_BIND_TCP)) {