selftests/landlock: Split signal_scoping_threads tests

JIRA: https://issues.redhat.com/browse/RHEL-125143

Upstream Status: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

commit bbe7227
Author: Mickaël Salaün <mic@digikod.net>
Date:   Tue Mar 18 17:14:41 2025 +0100

    selftests/landlock: Split signal_scoping_threads tests

    Split signal_scoping_threads tests into signal_scoping_thread_before
    and signal_scoping_thread_after.

    Use local variables for thread synchronization.  Fix exported function.
    Replace some asserts with expects.

    Fixes: c899496 ("selftests/landlock: Test signal scoping for threads")
    Cc: Günther Noack <gnoack@google.com>
    Cc: Tahera Fahimi <fahimitahera@gmail.com>
    Cc: stable@vger.kernel.org
    Link: https://lore.kernel.org/r/20250318161443.279194-7-mic@digikod.net
    Signed-off-by: Mickaël Salaün <mic@digikod.net>

Signed-off-by: Štěpán Horáček <shoracek@redhat.com>

Author: shoracek

tools/testing/selftests/landlock/scoped_signal_test.c

@@ -249,47 +249,66 @@ 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,
 };
 
-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(0, 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);