linux-kernel - [PATCH 3/3] selftests/seccomp: add test for NOTIF

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Date: Thu, 23 May 2024 01:45:40 +0000
From: Andrei Vagin <avagin@...gle.com>
To: Kees Cook <keescook@...omium.org>, Andy Lutomirski <luto@...capital.net>, 
	Will Drewry <wad@...omium.org>, Oleg Nesterov <oleg@...hat.com>, 
	Christian Brauner <brauner@...nel.org>
Cc: linux-kernel@...r.kernel.org, Tycho Andersen <tandersen@...flix.com>, 
	Andrei Vagin <avagin@...gle.com>, Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 3/3] selftests/seccomp: add test for NOTIF_RECV and unused filters

Add a new test case to check that SECCOMP_IOCTL_NOTIF_RECV returns when all
tasks have gone.

Signed-off-by: Andrei Vagin <avagin@...gle.com>
---
 tools/testing/selftests/seccomp/seccomp_bpf.c | 54 +++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index 783ebce8c4de..390781d7c951 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -3954,6 +3954,60 @@ TEST(user_notification_filter_empty)
 	EXPECT_GT((pollfd.revents & POLLHUP) ?: 0, 0);
 }
 
+TEST(user_ioctl_notification_filter_empty)
+{
+	pid_t pid;
+	long ret;
+	int status, p[2];
+	struct __clone_args args = {
+		.flags = CLONE_FILES,
+		.exit_signal = SIGCHLD,
+	};
+	struct seccomp_notif req = {};
+
+	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!");
+	}
+
+	if (__NR_clone3 < 0)
+		SKIP(return, "Test not built with clone3 support");
+
+	ASSERT_EQ(0, pipe(p));
+
+	pid = sys_clone3(&args, sizeof(args));
+	ASSERT_GE(pid, 0);
+
+	if (pid == 0) {
+		int listener;
+
+		listener = user_notif_syscall(__NR_mknodat, SECCOMP_FILTER_FLAG_NEW_LISTENER);
+		if (listener < 0)
+			_exit(EXIT_FAILURE);
+
+		if (dup2(listener, 200) != 200)
+			_exit(EXIT_FAILURE);
+		close(p[1]);
+		close(listener);
+		sleep(1);
+
+		_exit(EXIT_SUCCESS);
+	}
+	if (read(p[0], &status, 1) != 0)
+		_exit(EXIT_SUCCESS);
+	close(p[0]);
+	/*
+	 * The seccomp filter has become unused so we should be notified once
+	 * the kernel gets around to cleaning up task struct.
+	 */
+	EXPECT_EQ(ioctl(200, SECCOMP_IOCTL_NOTIF_RECV, &req), -1);
+	EXPECT_EQ(errno, ENOENT);
+
+	EXPECT_EQ(waitpid(pid, &status, 0), pid);
+	EXPECT_EQ(true, WIFEXITED(status));
+	EXPECT_EQ(0, WEXITSTATUS(status));
+}
+
 static void *do_thread(void *data)
 {
 	return NULL;
-- 
2.45.1.288.g0e0cd299f1-goog