Merge tag 'landlock-7.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux

Pull landlock fix from Mickaël Salaün:
 "This fixes TCP Fast Open support, specific test environments, and doc
  warnings"

* tag 'landlock-7.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux:
  selftests/landlock: Skip scoped_signal subtest with MSG_OOB if not available
  selftests/landlock: Fix screwed up pointers in the scoped_signal_test
  landlock: Update formatting
  landlock: Fix kernel-doc for the nested quiet layer flag
  selftests/landlock: Add test for TCP fast open
  landlock: Fix TCP Fast Open connection bypass

security/landlock/net.c

@@ -351,6 +351,14 @@ static int hook_socket_sendmsg(struct socket *const sock,
 	access_mask_t access_request;
 	int ret = 0;
 
+	if ((msg->msg_flags & MSG_FASTOPEN) && address && sk_is_tcp(sock->sk)) {
+		ret = current_check_access_socket(
+			sock, address, addrlen, LANDLOCK_ACCESS_NET_CONNECT_TCP,
+			true);
+		if (ret != 0)
+			return ret;
+	}
+
 	if (sk_is_udp(sock->sk))
 		access_request = LANDLOCK_ACCESS_NET_CONNECT_SEND_UDP;
 	else

security/landlock/ruleset.h

@@ -35,8 +35,8 @@ struct landlock_layer {
 	 */
 	struct {
 		/**
-		 * @quiet: Suppresses denial logs for the object covered by this
-		 * rule in this domain.  For filesystem rules, this inherits
+		 * @flags.quiet: Suppresses denial logs for the object covered by
+		 * this rule in this domain.  For filesystem rules, this inherits
 		 * down the file hierarchy.
 		 */
 		u8 quiet : 1;

security/landlock/task.c

@@ -95,8 +95,7 @@ static int hook_ptrace_access_check(struct task_struct *const child,
 	if (!parent_subject)
 		return 0;
 
-	scoped_guard(rcu)
-	{
+	scoped_guard(rcu) {
 		const struct landlock_ruleset *const child_dom =
 			landlock_get_task_domain(child);
 		err = domain_ptrace(parent_subject->domain, child_dom);
@@ -370,8 +369,7 @@ static int hook_task_kill(struct task_struct *const p,
 	if (!subject)
 		return 0;
 
-	scoped_guard(rcu)
-	{
+	scoped_guard(rcu) {
 		is_scoped = domain_is_scoped(subject->domain,
 					     landlock_get_task_domain(p),
 					     signal_scope.scope);
@@ -422,8 +420,7 @@ static int hook_file_send_sigiotask(struct task_struct *tsk,
 	if (task_tgid(tsk) == landlock_file(fown->file)->fown_tg)
 		return 0;
 
-	scoped_guard(rcu)
-	{
+	scoped_guard(rcu) {
 		is_scoped = domain_is_scoped(subject->domain,
 					     landlock_get_task_domain(tsk),
 					     signal_scope.scope);

tools/testing/selftests/landlock/net_test.c

@@ -1281,6 +1281,103 @@ TEST_F(protocol, connect_unspec)
 	EXPECT_EQ(0, close(bind_fd));
 }
 
+TEST_F(protocol, tcp_fastopen)
+{
+	const bool restricted = variant->sandbox == TCP_SANDBOX &&
+				variant->prot.type == SOCK_STREAM &&
+				(variant->prot.protocol == IPPROTO_TCP ||
+				 variant->prot.protocol == IPPROTO_IP) &&
+				(variant->prot.domain == AF_INET ||
+				 variant->prot.domain == AF_INET6);
+	const struct landlock_ruleset_attr ruleset_attr = {
+		.handled_access_net = LANDLOCK_ACCESS_NET_CONNECT_TCP,
+	};
+	int bind_fd, client_fd, status;
+	char buf;
+	pid_t child;
+
+	bind_fd = socket_variant(&self->srv0);
+	ASSERT_LE(0, bind_fd);
+	EXPECT_EQ(0, bind_variant(bind_fd, &self->srv0));
+	if (self->srv0.protocol.type == SOCK_STREAM)
+		EXPECT_EQ(0, listen(bind_fd, backlog));
+
+	child = fork();
+	ASSERT_LE(0, child);
+	if (child == 0) {
+		int connect_fd, ret;
+
+		/* Closes listening socket for the child. */
+		EXPECT_EQ(0, close(bind_fd));
+
+		connect_fd = socket_variant(&self->srv0);
+		ASSERT_LE(0, connect_fd);
+
+		if (variant->sandbox == TCP_SANDBOX) {
+			const int ruleset_fd = landlock_create_ruleset(
+				&ruleset_attr, sizeof(ruleset_attr), 0);
+			ASSERT_LE(0, ruleset_fd);
+
+			enforce_ruleset(_metadata, ruleset_fd);
+			EXPECT_EQ(0, close(ruleset_fd));
+		}
+
+		/* Fast Open with no address. */
+		ret = sendto_variant(connect_fd, NULL, NULL, 0, MSG_FASTOPEN);
+		if (self->srv0.protocol.domain == AF_UNIX) {
+			EXPECT_EQ(-ENOTCONN, ret);
+		} else if (self->srv0.protocol.type == SOCK_DGRAM) {
+			EXPECT_EQ(-EDESTADDRREQ, ret);
+		} else {
+			EXPECT_EQ(-EINVAL, ret);
+		}
+
+		/* Fast Open to a denied address. */
+		ret = sendto_variant(connect_fd, &self->srv0, "A", 1,
+				     MSG_FASTOPEN);
+		if (restricted) {
+			EXPECT_EQ(-EACCES, ret);
+		} else if (self->srv0.protocol.domain == AF_UNIX &&
+			   self->srv0.protocol.type == SOCK_STREAM) {
+			EXPECT_EQ(-EOPNOTSUPP, ret);
+		} else {
+			EXPECT_EQ(0, ret);
+		}
+
+		EXPECT_EQ(0, close(connect_fd));
+		_exit(_metadata->exit_code);
+		return;
+	}
+
+	client_fd = bind_fd;
+	if (!restricted && self->srv0.protocol.type == SOCK_STREAM &&
+	    self->srv0.protocol.domain != AF_UNIX) {
+		client_fd = accept(bind_fd, NULL, 0);
+		ASSERT_LE(0, client_fd);
+	}
+
+	if (restricted) {
+		EXPECT_EQ(-1, read(client_fd, &buf, 1));
+		EXPECT_EQ(ENOTCONN, errno);
+	} else if (self->srv0.protocol.domain == AF_UNIX &&
+		   self->srv0.protocol.type == SOCK_STREAM) {
+		EXPECT_EQ(-1, read(client_fd, &buf, 1));
+		EXPECT_EQ(EINVAL, errno);
+	} else {
+		EXPECT_EQ(1, read(client_fd, &buf, 1));
+		EXPECT_EQ('A', buf);
+	}
+
+	EXPECT_EQ(child, waitpid(child, &status, 0));
+	EXPECT_EQ(1, WIFEXITED(status));
+	EXPECT_EQ(EXIT_SUCCESS, WEXITSTATUS(status));
+
+	if (client_fd != bind_fd)
+		EXPECT_LE(0, close(client_fd));
+
+	EXPECT_EQ(0, close(bind_fd));
+}
+
 TEST_F(protocol, sendmsg_stream)
 {
 	int srv0_fd, tmp_fd, client_fd, res;

tools/testing/selftests/landlock/scoped_signal_test.c

@@ -249,12 +249,12 @@ TEST_F(scoped_domains, check_access_signal)
 		_metadata->exit_code = KSFT_FAIL;
 }
 
-enum thread_return {
-	THREAD_INVALID = 0,
-	THREAD_SUCCESS = 1,
-	THREAD_ERROR = 2,
-	THREAD_TEST_FAILED = 3,
-};
+/* clang-format off */
+#define THREAD_INVALID		((void *)0)
+#define THREAD_SUCCESS		((void *)1)
+#define THREAD_ERROR		((void *)2)
+#define THREAD_TEST_FAILED	((void *)3)
+/* clang-format on */
 
 static void *thread_sync(void *arg)
 {
@@ -262,15 +262,15 @@ static void *thread_sync(void *arg)
 	char buf;
 
 	if (read(pipe_read, &buf, 1) != 1)
-		return (void *)THREAD_ERROR;
+		return THREAD_ERROR;
 
-	return (void *)THREAD_SUCCESS;
+	return THREAD_SUCCESS;
 }
 
 TEST(signal_scoping_thread_before)
 {
 	pthread_t no_sandbox_thread;
-	enum thread_return ret = THREAD_INVALID;
+	void *ret = THREAD_INVALID;
 	int thread_pipe[2];
 
 	drop_caps(_metadata);
@@ -285,7 +285,7 @@ TEST(signal_scoping_thread_before)
 	EXPECT_EQ(0, pthread_kill(no_sandbox_thread, 0));
 	EXPECT_EQ(1, write(thread_pipe[1], ".", 1));
 
-	EXPECT_EQ(0, pthread_join(no_sandbox_thread, (void **)&ret));
+	EXPECT_EQ(0, pthread_join(no_sandbox_thread, &ret));
 	EXPECT_EQ(THREAD_SUCCESS, ret);
 
 	EXPECT_EQ(0, close(thread_pipe[0]));
@@ -295,7 +295,7 @@ TEST(signal_scoping_thread_before)
 TEST(signal_scoping_thread_after)
 {
 	pthread_t scoped_thread;
-	enum thread_return ret = THREAD_INVALID;
+	void *ret = THREAD_INVALID;
 	int thread_pipe[2];
 
 	drop_caps(_metadata);
@@ -310,7 +310,7 @@ TEST(signal_scoping_thread_after)
 	EXPECT_EQ(0, pthread_kill(scoped_thread, 0));
 	EXPECT_EQ(1, write(thread_pipe[1], ".", 1));
 
-	EXPECT_EQ(0, pthread_join(scoped_thread, (void **)&ret));
+	EXPECT_EQ(0, pthread_join(scoped_thread, &ret));
 	EXPECT_EQ(THREAD_SUCCESS, ret);
 
 	EXPECT_EQ(0, close(thread_pipe[0]));
@@ -327,20 +327,20 @@ void *thread_setuid(void *ptr)
 	char buf;
 
 	if (read(arg->pipe_read, &buf, 1) != 1)
-		return (void *)THREAD_ERROR;
+		return THREAD_ERROR;
 
 	/* libc's setuid() should update all thread's credentials. */
 	if (getuid() != arg->new_uid)
-		return (void *)THREAD_TEST_FAILED;
+		return THREAD_TEST_FAILED;
 
-	return (void *)THREAD_SUCCESS;
+	return THREAD_SUCCESS;
 }
 
 TEST(signal_scoping_thread_setuid)
 {
 	struct thread_setuid_args arg;
 	pthread_t no_sandbox_thread;
-	enum thread_return ret = THREAD_INVALID;
+	void *ret = THREAD_INVALID;
 	int pipe_parent[2];
 	int prev_uid;
 
@@ -367,7 +367,7 @@ TEST(signal_scoping_thread_setuid)
 	EXPECT_EQ(arg.new_uid, getuid());
 	EXPECT_EQ(1, write(pipe_parent[1], ".", 1));
 
-	EXPECT_EQ(0, pthread_join(no_sandbox_thread, (void **)&ret));
+	EXPECT_EQ(0, pthread_join(no_sandbox_thread, &ret));
 	EXPECT_EQ(THREAD_SUCCESS, ret);
 
 	clear_cap(_metadata, CAP_SETUID);
@@ -400,6 +400,24 @@ static int setup_signal_handler(int signal)
 	return sigaction(SIGURG, &sa, NULL);
 }
 
+/*
+ * MSG_OOB might be disabled in the kernel via the CONFIG_AF_UNIX_OOB
+ * switch, so this function can be used for probing for its availability.
+ */
+static bool has_af_unix_oob(void)
+{
+	bool available = false;
+	int sp[2];
+
+	if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) == 0) {
+		available = (send(sp[0], ".", 1, MSG_OOB) == 1);
+		close(sp[0]);
+		close(sp[1]);
+	}
+
+	return available;
+}
+
 /* clang-format off */
 FIXTURE(fown) {};
 /* clang-format on */
@@ -462,6 +480,9 @@ TEST_F(fown, sigurg_socket)
 	int pipe_parent[2], pipe_child[2];
 	pid_t child;
 
+	if (!has_af_unix_oob())
+		SKIP(return, "CONFIG_AF_UNIX_OOB / MSG_OOB not available");
+
 	memset(&server_address, 0, sizeof(server_address));
 	set_unix_address(&server_address, 0);
 
@@ -667,20 +688,20 @@ static void *thread_setown_scoped(void *arg)
 	ruleset_fd =
 		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
 	if (ruleset_fd < 0)
-		return (void *)THREAD_ERROR;
+		return THREAD_ERROR;
 	if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) ||
 	    landlock_restrict_self(ruleset_fd, 0)) {
 		close(ruleset_fd);
-		return (void *)THREAD_ERROR;
+		return THREAD_ERROR;
 	}
 	close(ruleset_fd);
 
 	/* Makes this process group own the SIGIO source. */
 	if (fcntl(fd, F_SETSIG, SIGURG) || fcntl(fd, F_SETOWN, -getpgrp()) ||
 	    fcntl(fd, F_SETFL, O_ASYNC))
-		return (void *)THREAD_ERROR;
+		return THREAD_ERROR;
 
-	return (void *)THREAD_SUCCESS;
+	return THREAD_SUCCESS;
 }
 
 /*
@@ -702,7 +723,7 @@ TEST(sigio_to_pgid_self)
 {
 	int trigger[2];
 	pthread_t thread;
-	enum thread_return ret = THREAD_INVALID;
+	void *ret = THREAD_INVALID;
 	int i;
 
 	drop_caps(_metadata);
@@ -722,7 +743,7 @@ TEST(sigio_to_pgid_self)
 	 */
 	ASSERT_EQ(0, pthread_create(&thread, NULL, thread_setown_scoped,
 				    &trigger[0]));
-	ASSERT_EQ(0, pthread_join(thread, (void **)&ret));
+	ASSERT_EQ(0, pthread_join(thread, &ret));
 	ASSERT_EQ(THREAD_SUCCESS, ret);
 
 	/* Fans SIGURG out to the process group. */