[PATCH 2/2] tests: test seccomp filter notifications

[Christian Brauner]

This verifies we're correctly notified when a seccomp filter becomes
unused when a notifier is in use.

Signed-off-by: Christian Brauner <christian.brauner@xxxxxxxxxx>
---
 tools/testing/selftests/seccomp/seccomp_bpf.c | 137 ++++++++++++++++++
 1 file changed, 137 insertions(+)

diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index c0aa46ce14f6..472b93b1c3d5 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -45,12 +45,14 @@
 #include <sys/socket.h>
 #include <sys/ioctl.h>
 #include <linux/kcmp.h>
+#include <sys/epoll.h>
 
 #include <unistd.h>
 #include <sys/syscall.h>
 #include <poll.h>
 
 #include "../kselftest_harness.h"
+#include "../clone3/clone3_selftests.h"
 
 #ifndef PR_SET_PTRACER
 # define PR_SET_PTRACER 0x59616d61
@@ -3686,6 +3688,141 @@ TEST(user_notification_continue)
 	}
 }
 
+TEST(user_notification_filter_empty)
+{
+	pid_t pid;
+	long ret;
+	int status;
+	struct pollfd pollfd;
+	struct clone_args args = {
+		.flags = CLONE_FILES,
+		.exit_signal = SIGCHLD,
+	};
+
+	ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
+	ASSERT_EQ(0, ret) {
+		TH_LOG("Kernel does not support PR_SET_NO_NEW_PRIVS!");
+	}
+
+	pid = sys_clone3(&args, sizeof(args));
+	ASSERT_GE(pid, 0);
+
+	if (pid == 0) {
+		int listener;
+
+		listener = user_trap_syscall(__NR_mknod, SECCOMP_FILTER_FLAG_NEW_LISTENER);
+		if (listener < 0)
+			_exit(EXIT_FAILURE);
+
+		if (dup2(listener, 200) != 200)
+			_exit(EXIT_FAILURE);
+
+		close(listener);
+
+		_exit(EXIT_SUCCESS);
+	}
+
+	EXPECT_EQ(waitpid(pid, &status, 0), pid);
+	EXPECT_EQ(true, WIFEXITED(status));
+	EXPECT_EQ(0, WEXITSTATUS(status));
+
+	/*
+	 * The seccomp filter has become unused so we should be notified once
+	 * the kernel gets around to cleaning up task struct.
+	 */
+	pollfd.fd = 200;
+	pollfd.events = POLLHUP;
+
+	EXPECT_GT(poll(&pollfd, 1, -1), 0);
+	EXPECT_GT((pollfd.revents & POLLHUP) ?: 0, 0);
+}
+
+static void *do_thread(void *data)
+{
+	return NULL;
+}
+
+TEST(user_notification_filter_empty_threaded)
+{
+	pid_t pid;
+	long ret;
+	int status;
+	struct pollfd pollfd;
+	struct clone_args args = {
+		.flags = CLONE_FILES,
+		.exit_signal = SIGCHLD,
+	};
+
+	ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
+	ASSERT_EQ(0, ret) {
+		TH_LOG("Kernel does not support PR_SET_NO_NEW_PRIVS!");
+	}
+
+	pid = sys_clone3(&args, sizeof(args));
+	ASSERT_GE(pid, 0);
+
+	if (pid == 0) {
+		pid_t pid1, pid2;
+		int listener, status;
+		pthread_t thread;
+
+		listener = user_trap_syscall(__NR_dup, SECCOMP_FILTER_FLAG_NEW_LISTENER);
+		if (listener < 0)
+			_exit(EXIT_FAILURE);
+
+		if (dup2(listener, 200) != 200)
+			_exit(EXIT_FAILURE);
+
+		close(listener);
+
+		pid1 = fork();
+		if (pid1 < 0)
+			_exit(EXIT_FAILURE);
+
+		if (pid1 == 0)
+			_exit(EXIT_SUCCESS);
+
+		pid2 = fork();
+		if (pid2 < 0)
+			_exit(EXIT_FAILURE);
+
+		if (pid2 == 0)
+			_exit(EXIT_SUCCESS);
+
+		if (pthread_create(&thread, NULL, do_thread, NULL) ||
+		    pthread_join(thread, NULL))
+			_exit(EXIT_FAILURE);
+
+		if (pthread_create(&thread, NULL, do_thread, NULL) ||
+		    pthread_join(thread, NULL))
+			_exit(EXIT_FAILURE);
+
+		if (waitpid(pid1, &status, 0) != pid1 || !WIFEXITED(status) ||
+		    WEXITSTATUS(status))
+			_exit(EXIT_FAILURE);
+
+		if (waitpid(pid2, &status, 0) != pid2 || !WIFEXITED(status) ||
+		    WEXITSTATUS(status))
+			_exit(EXIT_FAILURE);
+
+		exit(EXIT_SUCCESS);
+	}
+
+	EXPECT_EQ(waitpid(pid, &status, 0), pid);
+	EXPECT_EQ(true, WIFEXITED(status));
+	EXPECT_EQ(0, WEXITSTATUS(status));
+
+	/*
+	 * The seccomp filter has become unused so we should be notified once
+	 * the kernel gets around to cleaning up task struct.
+	 */
+	pollfd.fd = 200;
+	pollfd.events = POLLHUP;
+
+	EXPECT_GT(poll(&pollfd, 1, -1), 0);
+	EXPECT_GT((pollfd.revents & POLLHUP) ?: 0, 0);
+}
+
 /*
  * TODO:
  * - add microbenchmarks
-- 
2.26.2