[PATCH v4 3/6] selftest/landlock: Add signal_scoping_threads test

This patch expands the signal scoping tests with pthread_kill(3) It
tests if an scoped thread can send signal to a process in the same
scoped domain, or a non-sandboxed thread.

Signed-off-by: Tahera Fahimi <[email protected]>
---
V4:
* Code improvement, and removing sleep(3) from threads.
* Commit improvement.
---
 .../selftests/landlock/scoped_signal_test.c   | 47 +++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/tools/testing/selftests/landlock/scoped_signal_test.c b/tools/testing/selftests/landlock/scoped_signal_test.c
index 8df027e22324..c71fb83b7147 100644
--- a/tools/testing/selftests/landlock/scoped_signal_test.c
+++ b/tools/testing/selftests/landlock/scoped_signal_test.c
@@ -9,6 +9,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <linux/landlock.h>
+#include <pthread.h>
 #include <signal.h>
 #include <sys/prctl.h>
 #include <sys/types.h>
@@ -222,4 +223,50 @@ 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)
+{
+	char buf;
+
+	if (read(thread_pipe[0], &buf, 1) != 1)
+		return (void *)THREAD_ERROR;
+
+	return (void *)THREAD_SUCCESS;
+}
+
+TEST(signal_scoping_threads)
+{
+	pthread_t no_sandbox_thread, scoped_thread;
+	enum thread_return ret = THREAD_INVALID;
+
+	ASSERT_EQ(0, pipe2(thread_pipe, O_CLOEXEC));
+
+	ASSERT_EQ(0,
+		  pthread_create(&no_sandbox_thread, NULL, thread_func, NULL));
+	/* Restrict the domain after creating the first thread. */
+	create_scoped_domain(_metadata, LANDLOCK_SCOPED_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_join(no_sandbox_thread, (void **)&ret));
+	EXPECT_EQ(THREAD_SUCCESS, ret);
+	EXPECT_EQ(0, pthread_join(scoped_thread, (void **)&ret));
+	EXPECT_EQ(THREAD_SUCCESS, ret);
+
+	EXPECT_EQ(0, close(thread_pipe[0]));
+	EXPECT_EQ(0, close(thread_pipe[1]));
+}
+
 TEST_HARNESS_MAIN
-- 
2.34.1