Add test validating that socket creation with accept(2) is not restricted
by Landlock.

Signed-off-by: Mikhail Ivanov <ivanov.mikhail1@huawei-partners.com>
---
Changes since v3:
* Minor fixes.
---
 .../testing/selftests/landlock/socket_test.c  | 62 +++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/tools/testing/selftests/landlock/socket_test.c b/tools/testing/selftests/landlock/socket_test.c
index e9f56a86f456..ea1590e555b7 100644
--- a/tools/testing/selftests/landlock/socket_test.c
+++ b/tools/testing/selftests/landlock/socket_test.c
@@ -1049,4 +1049,66 @@ TEST_F(connection_restriction, sctp_peeloff)
 	ASSERT_EQ(0, close(server_fd));
 }
 
+TEST_F(connection_restriction, accept)
+{
+	int status;
+	pid_t child;
+	struct sockaddr_in addr;
+	int server_fd, client_fd;
+	const struct landlock_ruleset_attr ruleset_attr = {
+		.handled_access_socket = LANDLOCK_ACCESS_SOCKET_CREATE,
+	};
+
+	server_fd = socket(AF_INET, SOCK_STREAM | SOCK_CLOEXEC, 0);
+	ASSERT_LE(0, server_fd);
+
+	addr.sin_family = AF_INET;
+	addr.sin_port = htons(loopback_port);
+	addr.sin_addr.s_addr = inet_addr(loopback_ipv4);
+
+	ASSERT_EQ(0, bind(server_fd, &addr, sizeof(addr)));
+	ASSERT_EQ(0, listen(server_fd, backlog));
+
+	child = fork();
+	ASSERT_LE(0, child);
+	if (child == 0) {
+		/* Connects to server once and exits. */
+
+		/* Closes listening socket for the child. */
+		ASSERT_EQ(0, close(server_fd));
+
+		client_fd = socket(AF_INET, SOCK_STREAM | SOCK_CLOEXEC, 0);
+		ASSERT_LE(0, client_fd);
+
+		ASSERT_EQ(0, connect(client_fd, &addr, sizeof(addr)));
+
+		ASSERT_EQ(0, close(client_fd));
+		_exit(_metadata->exit_code);
+		return;
+	}
+
+	if (variant->sandboxed) {
+		int ruleset_fd;
+
+		ruleset_fd = landlock_create_ruleset(&ruleset_attr,
+						     sizeof(ruleset_attr), 0);
+		ASSERT_LE(0, ruleset_fd);
+
+		enforce_ruleset(_metadata, ruleset_fd);
+		ASSERT_EQ(0, close(ruleset_fd));
+	}
+
+	client_fd = accept(server_fd, NULL, 0);
+
+	/* accept(2) should not be restricted by Landlock. */
+	ASSERT_LE(0, client_fd);
+
+	ASSERT_EQ(child, waitpid(child, &status, 0));
+	ASSERT_EQ(1, WIFEXITED(status));
+	ASSERT_EQ(EXIT_SUCCESS, WEXITSTATUS(status));
+
+	ASSERT_EQ(0, close(server_fd));
+	ASSERT_EQ(0, close(client_fd));
+}
+
 TEST_HARNESS_MAIN
-- 
2.34.1