v4.19.13 snapshot.
diff --git a/net/ipv6/tunnel6.c b/net/ipv6/tunnel6.c
new file mode 100644
index 0000000..dae25ca
--- /dev/null
+++ b/net/ipv6/tunnel6.c
@@ -0,0 +1,193 @@
+/*
+ * Copyright (C)2003,2004 USAGI/WIDE Project
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors Mitsuru KANDA <mk@linux-ipv6.org>
+ * YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
+ */
+
+#define pr_fmt(fmt) "IPv6: " fmt
+
+#include <linux/icmpv6.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <net/ipv6.h>
+#include <net/protocol.h>
+#include <net/xfrm.h>
+
+static struct xfrm6_tunnel __rcu *tunnel6_handlers __read_mostly;
+static struct xfrm6_tunnel __rcu *tunnel46_handlers __read_mostly;
+static DEFINE_MUTEX(tunnel6_mutex);
+
+int xfrm6_tunnel_register(struct xfrm6_tunnel *handler, unsigned short family)
+{
+ struct xfrm6_tunnel __rcu **pprev;
+ struct xfrm6_tunnel *t;
+ int ret = -EEXIST;
+ int priority = handler->priority;
+
+ mutex_lock(&tunnel6_mutex);
+
+ for (pprev = (family == AF_INET6) ? &tunnel6_handlers : &tunnel46_handlers;
+ (t = rcu_dereference_protected(*pprev,
+ lockdep_is_held(&tunnel6_mutex))) != NULL;
+ pprev = &t->next) {
+ if (t->priority > priority)
+ break;
+ if (t->priority == priority)
+ goto err;
+ }
+
+ handler->next = *pprev;
+ rcu_assign_pointer(*pprev, handler);
+
+ ret = 0;
+
+err:
+ mutex_unlock(&tunnel6_mutex);
+
+ return ret;
+}
+EXPORT_SYMBOL(xfrm6_tunnel_register);
+
+int xfrm6_tunnel_deregister(struct xfrm6_tunnel *handler, unsigned short family)
+{
+ struct xfrm6_tunnel __rcu **pprev;
+ struct xfrm6_tunnel *t;
+ int ret = -ENOENT;
+
+ mutex_lock(&tunnel6_mutex);
+
+ for (pprev = (family == AF_INET6) ? &tunnel6_handlers : &tunnel46_handlers;
+ (t = rcu_dereference_protected(*pprev,
+ lockdep_is_held(&tunnel6_mutex))) != NULL;
+ pprev = &t->next) {
+ if (t == handler) {
+ *pprev = handler->next;
+ ret = 0;
+ break;
+ }
+ }
+
+ mutex_unlock(&tunnel6_mutex);
+
+ synchronize_net();
+
+ return ret;
+}
+EXPORT_SYMBOL(xfrm6_tunnel_deregister);
+
+#define for_each_tunnel_rcu(head, handler) \
+ for (handler = rcu_dereference(head); \
+ handler != NULL; \
+ handler = rcu_dereference(handler->next)) \
+
+static int tunnel6_rcv(struct sk_buff *skb)
+{
+ struct xfrm6_tunnel *handler;
+
+ if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
+ goto drop;
+
+ for_each_tunnel_rcu(tunnel6_handlers, handler)
+ if (!handler->handler(skb))
+ return 0;
+
+ icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
+
+drop:
+ kfree_skb(skb);
+ return 0;
+}
+
+static int tunnel46_rcv(struct sk_buff *skb)
+{
+ struct xfrm6_tunnel *handler;
+
+ if (!pskb_may_pull(skb, sizeof(struct iphdr)))
+ goto drop;
+
+ for_each_tunnel_rcu(tunnel46_handlers, handler)
+ if (!handler->handler(skb))
+ return 0;
+
+ icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
+
+drop:
+ kfree_skb(skb);
+ return 0;
+}
+
+static void tunnel6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
+ u8 type, u8 code, int offset, __be32 info)
+{
+ struct xfrm6_tunnel *handler;
+
+ for_each_tunnel_rcu(tunnel6_handlers, handler)
+ if (!handler->err_handler(skb, opt, type, code, offset, info))
+ break;
+}
+
+static void tunnel46_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
+ u8 type, u8 code, int offset, __be32 info)
+{
+ struct xfrm6_tunnel *handler;
+
+ for_each_tunnel_rcu(tunnel46_handlers, handler)
+ if (!handler->err_handler(skb, opt, type, code, offset, info))
+ break;
+}
+
+static const struct inet6_protocol tunnel6_protocol = {
+ .handler = tunnel6_rcv,
+ .err_handler = tunnel6_err,
+ .flags = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
+};
+
+static const struct inet6_protocol tunnel46_protocol = {
+ .handler = tunnel46_rcv,
+ .err_handler = tunnel46_err,
+ .flags = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
+};
+
+static int __init tunnel6_init(void)
+{
+ if (inet6_add_protocol(&tunnel6_protocol, IPPROTO_IPV6)) {
+ pr_err("%s: can't add protocol\n", __func__);
+ return -EAGAIN;
+ }
+ if (inet6_add_protocol(&tunnel46_protocol, IPPROTO_IPIP)) {
+ pr_err("%s: can't add protocol\n", __func__);
+ inet6_del_protocol(&tunnel6_protocol, IPPROTO_IPV6);
+ return -EAGAIN;
+ }
+ return 0;
+}
+
+static void __exit tunnel6_fini(void)
+{
+ if (inet6_del_protocol(&tunnel46_protocol, IPPROTO_IPIP))
+ pr_err("%s: can't remove protocol\n", __func__);
+ if (inet6_del_protocol(&tunnel6_protocol, IPPROTO_IPV6))
+ pr_err("%s: can't remove protocol\n", __func__);
+}
+
+module_init(tunnel6_init);
+module_exit(tunnel6_fini);
+MODULE_LICENSE("GPL");