tun: Check that net ns of tun device is dumped

Similar to socket logic, abort the dump,
if tun is not related to any net ns, seen
before.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>

criu/tun.c

@@ -290,6 +290,7 @@ static int dump_tunfile(int lfd, u32 id, const struct fd_parms *p)
 	struct cr_img *img;
 	FileEntry fe = FILE_ENTRY__INIT;
 	TunfileEntry tfe = TUNFILE_ENTRY__INIT;
+	struct ns_id *ns;
 	struct ifreq ifr;
 
 	if (!(root_ns_mask & CLONE_NEWNET)) {
@@ -297,6 +298,14 @@ static int dump_tunfile(int lfd, u32 id, const struct fd_parms *p)
 		return -1;
 	}
 
+	if (kdat.tun_ns) {
+		ns = get_socket_ns(lfd);
+		if (!ns) {
+			pr_err("No net_ns for tun device\n");
+			return -1;
+		}
+	}
+
 	if (dump_one_reg_file(lfd, id, p))
 		return -1;