Merge tag 'seccomp-v5.5-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull seccomp fixes from Kees Cook:
"Fixes for seccomp_notify_ioctl uapi sanity from Sargun Dhillon.

The bulk of this is fixing the surrounding samples and selftests so
that seccomp can correctly validate the seccomp_notify_ioctl buffer as
being initially zeroed.

Summary:

- Fix samples and selftests to zero passed-in buffer

- Enforce zeroed buffer checking

- Verify buffer sanity check in selftest"

* tag 'seccomp-v5.5-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
selftests/seccomp: Catch garbage on SECCOMP_IOCTL_NOTIF_RECV
seccomp: Check that seccomp_notif is zeroed out by the user
selftests/seccomp: Zero out seccomp_notif
samples/seccomp: Zero out members based on seccomp_notif_sizes

kernel/seccomp.c

···
 	struct seccomp_notif unotif;
 	ssize_t ret;
 
+	/* Verify that we're not given garbage to keep struct extensible. */
+	ret = check_zeroed_user(buf, sizeof(unotif));
+	if (ret < 0)
+		return ret;
+	if (!ret)
+		return -EINVAL;
+
 	memset(&unotif, 0, sizeof(unotif));
 
 	ret = down_interruptible(&filter->notif->request);

samples/seccomp/user-trap.c

···
 		req = malloc(sizes.seccomp_notif);
 		if (!req)
 			goto out_close;
-		memset(req, 0, sizeof(*req));
 
 		resp = malloc(sizes.seccomp_notif_resp);
 		if (!resp)
 			goto out_req;
-		memset(resp, 0, sizeof(*resp));
+		memset(resp, 0, sizes.seccomp_notif_resp);
 
 		while (1) {
+			memset(req, 0, sizes.seccomp_notif);
 			if (ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, req)) {
 				perror("ioctl recv");
 				goto out_resp;

tools/testing/selftests/seccomp/seccomp_bpf.c

···
 	EXPECT_GT(poll(&pollfd, 1, -1), 0);
 	EXPECT_EQ(pollfd.revents, POLLIN);
 
-	EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
+	/* Test that we can't pass garbage to the kernel. */
+	memset(&req, 0, sizeof(req));
+	req.pid = -1;
+	errno = 0;
+	ret = ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req);
+	EXPECT_EQ(-1, ret);
+	EXPECT_EQ(EINVAL, errno);
+
+	if (ret) {
+		req.pid = 0;
+		EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
+	}
 
 	pollfd.fd = listener;
 	pollfd.events = POLLIN | POLLOUT;
···
 
 	close(sk_pair[1]);
 
+	memset(&req, 0, sizeof(req));
 	EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
 
 	EXPECT_EQ(kill(pid, SIGUSR1), 0);
···
 	EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_SEND, &resp), -1);
 	EXPECT_EQ(errno, ENOENT);
 
+	memset(&req, 0, sizeof(req));
 	EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
 
 	resp.id = req.id;