[RFC PATCH v2 9/9] samples/landlock: Support LANDLOCK_ACCESS_NET_LISTEN

[Mikhail Ivanov]

Extend sample with TCP listen control logic.

Signed-off-by: Mikhail Ivanov <ivanov.mikhail1 at huawei-partners.com>
---
 samples/landlock/sandboxer.c | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
index e8223c3e781a..3f50cb3f8039 100644
--- a/samples/landlock/sandboxer.c
+++ b/samples/landlock/sandboxer.c
@@ -55,6 +55,7 @@ static inline int landlock_restrict_self(const int ruleset_fd,
 #define ENV_FS_RW_NAME "LL_FS_RW"
 #define ENV_TCP_BIND_NAME "LL_TCP_BIND"
 #define ENV_TCP_CONNECT_NAME "LL_TCP_CONNECT"
+#define ENV_TCP_LISTEN_NAME "LL_TCP_LISTEN"
 #define ENV_DELIMITER ":"
 
 static int parse_path(char *env_path, const char ***const path_list)
@@ -208,7 +209,7 @@ static int populate_ruleset_net(const char *const env_var, const int ruleset_fd,
 
 /* clang-format on */
 
-#define LANDLOCK_ABI_LAST 5
+#define LANDLOCK_ABI_LAST 6
 
 int main(const int argc, char *const argv[], char *const *const envp)
 {
@@ -222,15 +223,16 @@ int main(const int argc, char *const argv[], char *const *const envp)
 	struct landlock_ruleset_attr ruleset_attr = {
 		.handled_access_fs = access_fs_rw,
 		.handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP |
-				      LANDLOCK_ACCESS_NET_CONNECT_TCP,
+				      LANDLOCK_ACCESS_NET_CONNECT_TCP |
+				      LANDLOCK_ACCESS_NET_LISTEN_TCP,
 	};
 
 	if (argc < 2) {
 		fprintf(stderr,
-			"usage: %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\"%s "
+			"usage: %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\"%s "
 			"<cmd> [args]...\n\n",
 			ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME,
-			ENV_TCP_CONNECT_NAME, argv[0]);
+			ENV_TCP_CONNECT_NAME, ENV_TCP_LISTEN_NAME, argv[0]);
 		fprintf(stderr,
 			"Execute a command in a restricted environment.\n\n");
 		fprintf(stderr,
@@ -251,15 +253,19 @@ int main(const int argc, char *const argv[], char *const *const envp)
 		fprintf(stderr,
 			"* %s: list of ports allowed to connect (client).\n",
 			ENV_TCP_CONNECT_NAME);
+		fprintf(stderr,
+			"* %s: list of ports allowed to listen (server).\n",
+			ENV_TCP_LISTEN_NAME);
 		fprintf(stderr,
 			"\nexample:\n"
 			"%s=\"${PATH}:/lib:/usr:/proc:/etc:/dev/urandom\" "
 			"%s=\"/dev/null:/dev/full:/dev/zero:/dev/pts:/tmp\" "
 			"%s=\"9418\" "
 			"%s=\"80:443\" "
+			"%s=\"9418\" "
 			"%s bash -i\n\n",
 			ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME,
-			ENV_TCP_CONNECT_NAME, argv[0]);
+			ENV_TCP_CONNECT_NAME, ENV_TCP_LISTEN_NAME, argv[0]);
 		fprintf(stderr,
 			"This sandboxer can use Landlock features "
 			"up to ABI version %d.\n",
@@ -326,6 +332,11 @@ int main(const int argc, char *const argv[], char *const *const envp)
 	case 4:
 		/* Removes LANDLOCK_ACCESS_FS_IOCTL_DEV for ABI < 5 */
 		ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_IOCTL_DEV;
+		__attribute__((fallthrough));
+	case 5:
+		/* Removes LANDLOCK_ACCESS_NET_LISTEN support for ABI < 6 */
+		ruleset_attr.handled_access_net &=
+			~(LANDLOCK_ACCESS_NET_LISTEN_TCP);
 
 		fprintf(stderr,
 			"Hint: You should update the running kernel "
@@ -357,6 +368,12 @@ int main(const int argc, char *const argv[], char *const *const envp)
 		ruleset_attr.handled_access_net &=
 			~LANDLOCK_ACCESS_NET_CONNECT_TCP;
 	}
+	/* Removes listen access attribute if not supported by a user. */
+	env_port_name = getenv(ENV_TCP_LISTEN_NAME);
+	if (!env_port_name) {
+		ruleset_attr.handled_access_net &=
+			~LANDLOCK_ACCESS_NET_LISTEN_TCP;
+	}
 
 	ruleset_fd =
 		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
@@ -380,6 +397,10 @@ int main(const int argc, char *const argv[], char *const *const envp)
 				 LANDLOCK_ACCESS_NET_CONNECT_TCP)) {
 		goto err_close_ruleset;
 	}
+	if (populate_ruleset_net(ENV_TCP_LISTEN_NAME, ruleset_fd,
+				 LANDLOCK_ACCESS_NET_LISTEN_TCP)) {
+		goto err_close_ruleset;
+	}
 
 	if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
 		perror("Failed to restrict privileges");
-- 
2.34.1