[RFC PATCH v2 5/9] selftests/landlock: Test listen on connected socket

[Mikhail Ivanov]

Test checks that listen(2) doesn't wrongfully return -EACCES instead
of -EINVAL when trying to listen for an incorrect socket state.

Signed-off-by: Mikhail Ivanov <ivanov.mikhail1 at huawei-partners.com>
---

Changes since v1:
* Uses 'protocol' fixture instead of 'ipv4_tcp'.
* Minor fixes.
---
 tools/testing/selftests/landlock/net_test.c | 74 +++++++++++++++++++++
 1 file changed, 74 insertions(+)

diff --git a/tools/testing/selftests/landlock/net_test.c b/tools/testing/selftests/landlock/net_test.c
index b6fe9bde205f..551891b18b7a 100644
--- a/tools/testing/selftests/landlock/net_test.c
+++ b/tools/testing/selftests/landlock/net_test.c
@@ -926,6 +926,80 @@ TEST_F(protocol, connect_unspec)
 	EXPECT_EQ(0, close(bind_fd));
 }
 
+TEST_F(protocol, listen_on_connected)
+{
+	int bind_fd, status;
+	pid_t child;
+
+	if (variant->sandbox == TCP_SANDBOX) {
+		const struct landlock_ruleset_attr ruleset_attr = {
+			.handled_access_net = ACCESS_ALL,
+		};
+		const struct landlock_net_port_attr tcp_not_restricted_p0 = {
+			.allowed_access = ACCESS_ALL,
+			.port = self->srv0.port,
+		};
+		const struct landlock_net_port_attr tcp_denied_listen_p1 = {
+			.allowed_access = ACCESS_ALL &
+					  ~LANDLOCK_ACCESS_NET_LISTEN_TCP,
+			.port = self->srv1.port,
+		};
+		int ruleset_fd;
+
+		ruleset_fd = landlock_create_ruleset(&ruleset_attr,
+						     sizeof(ruleset_attr), 0);
+		ASSERT_LE(0, ruleset_fd);
+
+		/* Allows all actions for the first port. */
+		ASSERT_EQ(0,
+			  landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_PORT,
+					    &tcp_not_restricted_p0, 0));
+
+		/* Denies listening for the second port. */
+		ASSERT_EQ(0,
+			  landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_PORT,
+					    &tcp_denied_listen_p1, 0));
+
+		enforce_ruleset(_metadata, ruleset_fd);
+		EXPECT_EQ(0, close(ruleset_fd));
+	}
+
+	if (variant->prot.type != SOCK_STREAM)
+		SKIP(return, "listen(2) is supported only on stream sockets");
+
+	/* Initializes listening socket. */
+	bind_fd = socket_variant(&self->srv0);
+	ASSERT_LE(0, bind_fd);
+	EXPECT_EQ(0, bind_variant(bind_fd, &self->srv0));
+	EXPECT_EQ(0, listen_variant(bind_fd, backlog));
+
+	child = fork();
+	ASSERT_LE(0, child);
+	if (child == 0) {
+		int connect_fd;
+
+		/* Closes listening socket for the child. */
+		EXPECT_EQ(0, close(bind_fd));
+
+		connect_fd = socket_variant(&self->srv1);
+		ASSERT_LE(0, connect_fd);
+		EXPECT_EQ(0, connect_variant(connect_fd, &self->srv0));
+
+		/* Tries to listen on connected socket. */
+		EXPECT_EQ(-EINVAL, listen_variant(connect_fd, backlog));
+
+		EXPECT_EQ(0, close(connect_fd));
+		_exit(_metadata->exit_code);
+		return;
+	}
+
+	EXPECT_EQ(child, waitpid(child, &status, 0));
+	EXPECT_EQ(1, WIFEXITED(status));
+	EXPECT_EQ(EXIT_SUCCESS, WEXITSTATUS(status));
+
+	EXPECT_EQ(0, close(bind_fd));
+}
+
 FIXTURE(ipv4)
 {
 	struct service_fixture srv0, srv1;
-- 
2.34.1