1 files changed, 93 insertions, 15 deletions
diff --git a/tools/testing/selftests/landlock/scoped_signal_test.c b/tools/testing/selftests/landlock/scoped_signal_test.c
index 475ee62a832d..d8bf33417619 100644
--- a/tools/testing/selftests/landlock/scoped_signal_test.c
+++ b/tools/testing/selftests/landlock/scoped_signal_test.c
@@ -249,47 +249,67 @@ TEST_F(scoped_domains, check_access_signal)
 		_metadata->exit_code = KSFT_FAIL;
 }
 
-static int thread_pipe[2];
-
 enum thread_return {
 	THREAD_INVALID = 0,
 	THREAD_SUCCESS = 1,
 	THREAD_ERROR = 2,
+	THREAD_TEST_FAILED = 3,
 };
 
-void *thread_func(void *arg)
+static void *thread_sync(void *arg)
 {
+	const int pipe_read = *(int *)arg;
 	char buf;
 
-	if (read(thread_pipe[0], &buf, 1) != 1)
+	if (read(pipe_read, &buf, 1) != 1)
 		return (void *)THREAD_ERROR;
 
 	return (void *)THREAD_SUCCESS;
 }
 
-TEST(signal_scoping_threads)
+TEST(signal_scoping_thread_before)
 {
-	pthread_t no_sandbox_thread, scoped_thread;
+	pthread_t no_sandbox_thread;
 	enum thread_return ret = THREAD_INVALID;
+	int thread_pipe[2];
 
 	drop_caps(_metadata);
 	ASSERT_EQ(0, pipe2(thread_pipe, O_CLOEXEC));
 
-	ASSERT_EQ(0,
-		  pthread_create(&no_sandbox_thread, NULL, thread_func, NULL));
+	ASSERT_EQ(0, pthread_create(&no_sandbox_thread, NULL, thread_sync,
+				    &thread_pipe[0]));
 
-	/* Restricts the domain after creating the first thread. */
+	/* Enforces restriction after creating the thread. */
 	create_scoped_domain(_metadata, LANDLOCK_SCOPE_SIGNAL);
 
-	ASSERT_EQ(EPERM, pthread_kill(no_sandbox_thread, 0));
-	ASSERT_EQ(1, write(thread_pipe[1], ".", 1));
-
-	ASSERT_EQ(0, pthread_create(&scoped_thread, NULL, thread_func, NULL));
-	ASSERT_EQ(0, pthread_kill(scoped_thread, 0));
-	ASSERT_EQ(1, write(thread_pipe[1], ".", 1));
+	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(THREAD_SUCCESS, ret);
+
+	EXPECT_EQ(0, close(thread_pipe[0]));
+	EXPECT_EQ(0, close(thread_pipe[1]));
+}
+
+TEST(signal_scoping_thread_after)
+{
+	pthread_t scoped_thread;
+	enum thread_return ret = THREAD_INVALID;
+	int thread_pipe[2];
+
+	drop_caps(_metadata);
+	ASSERT_EQ(0, pipe2(thread_pipe, O_CLOEXEC));
+
+	/* Enforces restriction before creating the thread. */
+	create_scoped_domain(_metadata, LANDLOCK_SCOPE_SIGNAL);
+
+	ASSERT_EQ(0, pthread_create(&scoped_thread, NULL, thread_sync,
+				    &thread_pipe[0]));
+
+	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(THREAD_SUCCESS, ret);
 
@@ -297,6 +317,64 @@ TEST(signal_scoping_threads)
 	EXPECT_EQ(0, close(thread_pipe[1]));
 }
 
+struct thread_setuid_args {
+	int pipe_read, new_uid;
+};
+
+void *thread_setuid(void *ptr)
+{
+	const struct thread_setuid_args *arg = ptr;
+	char buf;
+
+	if (read(arg->pipe_read, &buf, 1) != 1)
+		return (void *)THREAD_ERROR;
+
+	/* libc's setuid() should update all thread's credentials. */
+	if (getuid() != arg->new_uid)
+		return (void *)THREAD_TEST_FAILED;
+
+	return (void *)THREAD_SUCCESS;
+}
+
+TEST(signal_scoping_thread_setuid)
+{
+	struct thread_setuid_args arg;
+	pthread_t no_sandbox_thread;
+	enum thread_return ret = THREAD_INVALID;
+	int pipe_parent[2];
+	int prev_uid;
+
+	disable_caps(_metadata);
+
+	/* This test does not need to be run as root. */
+	prev_uid = getuid();
+	arg.new_uid = prev_uid + 1;
+	EXPECT_LT(0, arg.new_uid);
+
+	ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC));
+	arg.pipe_read = pipe_parent[0];
+
+	/* Capabilities must be set before creating a new thread. */
+	set_cap(_metadata, CAP_SETUID);
+	ASSERT_EQ(0, pthread_create(&no_sandbox_thread, NULL, thread_setuid,
+				    &arg));
+
+	/* Enforces restriction after creating the thread. */
+	create_scoped_domain(_metadata, LANDLOCK_SCOPE_SIGNAL);
+
+	EXPECT_NE(arg.new_uid, getuid());
+	EXPECT_EQ(0, setuid(arg.new_uid));
+	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(THREAD_SUCCESS, ret);
+
+	clear_cap(_metadata, CAP_SETUID);
+	EXPECT_EQ(0, close(pipe_parent[0]));
+	EXPECT_EQ(0, close(pipe_parent[1]));
+}
+
 const short backlog = 10;
 
 static volatile sig_atomic_t signal_received;