Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1801 insertions, 0 deletions

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
new file mode 100644
index 000000000..a6ad0fe13
--- /dev/null
+++ b/net/ipv4/ip_gre.c
@@ -0,0 +1,1801 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *	Linux NET3:	GRE over IP protocol decoder.
+ *
+ *	Authors: Alexey Kuznetsov (kuznet@ms2.inr.ac.ru)
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/capability.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/skbuff.h>
+#include <linux/netdevice.h>
+#include <linux/in.h>
+#include <linux/tcp.h>
+#include <linux/udp.h>
+#include <linux/if_arp.h>
+#include <linux/if_vlan.h>
+#include <linux/init.h>
+#include <linux/in6.h>
+#include <linux/inetdevice.h>
+#include <linux/igmp.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/etherdevice.h>
+#include <linux/if_ether.h>
+
+#include <net/sock.h>
+#include <net/ip.h>
+#include <net/icmp.h>
+#include <net/protocol.h>
+#include <net/ip_tunnels.h>
+#include <net/arp.h>
+#include <net/checksum.h>
+#include <net/dsfield.h>
+#include <net/inet_ecn.h>
+#include <net/xfrm.h>
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
+#include <net/rtnetlink.h>
+#include <net/gre.h>
+#include <net/dst_metadata.h>
+#include <net/erspan.h>
+
+/*
+   Problems & solutions
+   --------------------
+
+   1. The most important issue is detecting local dead loops.
+   They would cause complete host lockup in transmit, which
+   would be "resolved" by stack overflow or, if queueing is enabled,
+   with infinite looping in net_bh.
+
+   We cannot track such dead loops during route installation,
+   it is infeasible task. The most general solutions would be
+   to keep skb->encapsulation counter (sort of local ttl),
+   and silently drop packet when it expires. It is a good
+   solution, but it supposes maintaining new variable in ALL
+   skb, even if no tunneling is used.
+
+   Current solution: xmit_recursion breaks dead loops. This is a percpu
+   counter, since when we enter the first ndo_xmit(), cpu migration is
+   forbidden. We force an exit if this counter reaches RECURSION_LIMIT
+
+   2. Networking dead loops would not kill routers, but would really
+   kill network. IP hop limit plays role of "t->recursion" in this case,
+   if we copy it from packet being encapsulated to upper header.
+   It is very good solution, but it introduces two problems:
+
+   - Routing protocols, using packets with ttl=1 (OSPF, RIP2),
+     do not work over tunnels.
+   - traceroute does not work. I planned to relay ICMP from tunnel,
+     so that this problem would be solved and traceroute output
+     would even more informative. This idea appeared to be wrong:
+     only Linux complies to rfc1812 now (yes, guys, Linux is the only
+     true router now :-)), all routers (at least, in neighbourhood of mine)
+     return only 8 bytes of payload. It is the end.
+
+   Hence, if we want that OSPF worked or traceroute said something reasonable,
+   we should search for another solution.
+
+   One of them is to parse packet trying to detect inner encapsulation
+   made by our node. It is difficult or even impossible, especially,
+   taking into account fragmentation. TO be short, ttl is not solution at all.
+
+   Current solution: The solution was UNEXPECTEDLY SIMPLE.
+   We force DF flag on tunnels with preconfigured hop limit,
+   that is ALL. :-) Well, it does not remove the problem completely,
+   but exponential growth of network traffic is changed to linear
+   (branches, that exceed pmtu are pruned) and tunnel mtu
+   rapidly degrades to value <68, where looping stops.
+   Yes, it is not good if there exists a router in the loop,
+   which does not force DF, even when encapsulating packets have DF set.
+   But it is not our problem! Nobody could accuse us, we made
+   all that we could make. Even if it is your gated who injected
+   fatal route to network, even if it were you who configured
+   fatal static route: you are innocent. :-)
+
+   Alexey Kuznetsov.
+ */
+
+static bool log_ecn_error = true;
+module_param(log_ecn_error, bool, 0644);
+MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN");
+
+static struct rtnl_link_ops ipgre_link_ops __read_mostly;
+static int ipgre_tunnel_init(struct net_device *dev);
+static void erspan_build_header(struct sk_buff *skb,
+				u32 id, u32 index,
+				bool truncate, bool is_ipv4);
+
+static unsigned int ipgre_net_id __read_mostly;
+static unsigned int gre_tap_net_id __read_mostly;
+static unsigned int erspan_net_id __read_mostly;
+
+static int ipgre_err(struct sk_buff *skb, u32 info,
+		     const struct tnl_ptk_info *tpi)
+{
+
+	/* All the routers (except for Linux) return only
+	   8 bytes of packet payload. It means, that precise relaying of
+	   ICMP in the real Internet is absolutely infeasible.
+
+	   Moreover, Cisco "wise men" put GRE key to the third word
+	   in GRE header. It makes impossible maintaining even soft
+	   state for keyed GRE tunnels with enabled checksum. Tell
+	   them "thank you".
+
+	   Well, I wonder, rfc1812 was written by Cisco employee,
+	   what the hell these idiots break standards established
+	   by themselves???
+	   */
+	struct net *net = dev_net(skb->dev);
+	struct ip_tunnel_net *itn;
+	const struct iphdr *iph;
+	const int type = icmp_hdr(skb)->type;
+	const int code = icmp_hdr(skb)->code;
+	unsigned int data_len = 0;
+	struct ip_tunnel *t;
+
+	if (tpi->proto == htons(ETH_P_TEB))
+		itn = net_generic(net, gre_tap_net_id);
+	else if (tpi->proto == htons(ETH_P_ERSPAN) ||
+		 tpi->proto == htons(ETH_P_ERSPAN2))
+		itn = net_generic(net, erspan_net_id);
+	else
+		itn = net_generic(net, ipgre_net_id);
+
+	iph = (const struct iphdr *)(icmp_hdr(skb) + 1);
+	t = ip_tunnel_lookup(itn, skb->dev->ifindex, tpi->flags,
+			     iph->daddr, iph->saddr, tpi->key);
+
+	if (!t)
+		return -ENOENT;
+
+	switch (type) {
+	default:
+	case ICMP_PARAMETERPROB:
+		return 0;
+
+	case ICMP_DEST_UNREACH:
+		switch (code) {
+		case ICMP_SR_FAILED:
+		case ICMP_PORT_UNREACH:
+			/* Impossible event. */
+			return 0;
+		default:
+			/* All others are translated to HOST_UNREACH.
+			   rfc2003 contains "deep thoughts" about NET_UNREACH,
+			   I believe they are just ether pollution. --ANK
+			 */
+			break;
+		}
+		break;
+
+	case ICMP_TIME_EXCEEDED:
+		if (code != ICMP_EXC_TTL)
+			return 0;
+		data_len = icmp_hdr(skb)->un.reserved[1] * 4; /* RFC 4884 4.1 */
+		break;
+
+	case ICMP_REDIRECT:
+		break;
+	}
+
+#if IS_ENABLED(CONFIG_IPV6)
+       if (tpi->proto == htons(ETH_P_IPV6) &&
+           !ip6_err_gen_icmpv6_unreach(skb, iph->ihl * 4 + tpi->hdr_len,
+				       type, data_len))
+               return 0;
+#endif
+
+	if (t->parms.iph.daddr == 0 ||
+	    ipv4_is_multicast(t->parms.iph.daddr))
+		return 0;
+
+	if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
+		return 0;
+
+	if (time_before(jiffies, t->err_time + IPTUNNEL_ERR_TIMEO))
+		t->err_count++;
+	else
+		t->err_count = 1;
+	t->err_time = jiffies;
+
+	return 0;
+}
+
+static void gre_err(struct sk_buff *skb, u32 info)
+{
+	/* All the routers (except for Linux) return only
+	 * 8 bytes of packet payload. It means, that precise relaying of
+	 * ICMP in the real Internet is absolutely infeasible.
+	 *
+	 * Moreover, Cisco "wise men" put GRE key to the third word
+	 * in GRE header. It makes impossible maintaining even soft
+	 * state for keyed
+	 * GRE tunnels with enabled checksum. Tell them "thank you".
+	 *
+	 * Well, I wonder, rfc1812 was written by Cisco employee,
+	 * what the hell these idiots break standards established
+	 * by themselves???
+	 */
+
+	const struct iphdr *iph = (struct iphdr *)skb->data;
+	const int type = icmp_hdr(skb)->type;
+	const int code = icmp_hdr(skb)->code;
+	struct tnl_ptk_info tpi;
+
+	if (gre_parse_header(skb, &tpi, NULL, htons(ETH_P_IP),
+			     iph->ihl * 4) < 0)
+		return;
+
+	if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
+		ipv4_update_pmtu(skb, dev_net(skb->dev), info,
+				 skb->dev->ifindex, IPPROTO_GRE);
+		return;
+	}
+	if (type == ICMP_REDIRECT) {
+		ipv4_redirect(skb, dev_net(skb->dev), skb->dev->ifindex,
+			      IPPROTO_GRE);
+		return;
+	}
+
+	ipgre_err(skb, info, &tpi);
+}
+
+static bool is_erspan_type1(int gre_hdr_len)
+{
+	/* Both ERSPAN type I (version 0) and type II (version 1) use
+	 * protocol 0x88BE, but the type I has only 4-byte GRE header,
+	 * while type II has 8-byte.
+	 */
+	return gre_hdr_len == 4;
+}
+
+static int erspan_rcv(struct sk_buff *skb, struct tnl_ptk_info *tpi,
+		      int gre_hdr_len)
+{
+	struct net *net = dev_net(skb->dev);
+	struct metadata_dst *tun_dst = NULL;
+	struct erspan_base_hdr *ershdr;
+	struct ip_tunnel_net *itn;
+	struct ip_tunnel *tunnel;
+	const struct iphdr *iph;
+	struct erspan_md2 *md2;
+	int ver;
+	int len;
+
+	itn = net_generic(net, erspan_net_id);
+	iph = ip_hdr(skb);
+	if (is_erspan_type1(gre_hdr_len)) {
+		ver = 0;
+		tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex,
+					  tpi->flags | TUNNEL_NO_KEY,
+					  iph->saddr, iph->daddr, 0);
+	} else {
+		ershdr = (struct erspan_base_hdr *)(skb->data + gre_hdr_len);
+		ver = ershdr->ver;
+		tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex,
+					  tpi->flags | TUNNEL_KEY,
+					  iph->saddr, iph->daddr, tpi->key);
+	}
+
+	if (tunnel) {
+		if (is_erspan_type1(gre_hdr_len))
+			len = gre_hdr_len;
+		else
+			len = gre_hdr_len + erspan_hdr_len(ver);
+
+		if (unlikely(!pskb_may_pull(skb, len)))
+			return PACKET_REJECT;
+
+		if (__iptunnel_pull_header(skb,
+					   len,
+					   htons(ETH_P_TEB),
+					   false, false) < 0)
+			goto drop;
+
+		if (tunnel->collect_md) {
+			struct erspan_metadata *pkt_md, *md;
+			struct ip_tunnel_info *info;
+			unsigned char *gh;
+			__be64 tun_id;
+			__be16 flags;
+
+			tpi->flags |= TUNNEL_KEY;
+			flags = tpi->flags;
+			tun_id = key32_to_tunnel_id(tpi->key);
+
+			tun_dst = ip_tun_rx_dst(skb, flags,
+						tun_id, sizeof(*md));
+			if (!tun_dst)
+				return PACKET_REJECT;
+
+			/* skb can be uncloned in __iptunnel_pull_header, so
+			 * old pkt_md is no longer valid and we need to reset
+			 * it
+			 */
+			gh = skb_network_header(skb) +
+			     skb_network_header_len(skb);
+			pkt_md = (struct erspan_metadata *)(gh + gre_hdr_len +
+							    sizeof(*ershdr));
+			md = ip_tunnel_info_opts(&tun_dst->u.tun_info);
+			md->version = ver;
+			md2 = &md->u.md2;
+			memcpy(md2, pkt_md, ver == 1 ? ERSPAN_V1_MDSIZE :
+						       ERSPAN_V2_MDSIZE);
+
+			info = &tun_dst->u.tun_info;
+			info->key.tun_flags |= TUNNEL_ERSPAN_OPT;
+			info->options_len = sizeof(*md);
+		}
+
+		skb_reset_mac_header(skb);
+		ip_tunnel_rcv(tunnel, skb, tpi, tun_dst, log_ecn_error);
+		return PACKET_RCVD;
+	}
+	return PACKET_REJECT;
+
+drop:
+	kfree_skb(skb);
+	return PACKET_RCVD;
+}
+
+static int __ipgre_rcv(struct sk_buff *skb, const struct tnl_ptk_info *tpi,
+		       struct ip_tunnel_net *itn, int hdr_len, bool raw_proto)
+{
+	struct metadata_dst *tun_dst = NULL;
+	const struct iphdr *iph;
+	struct ip_tunnel *tunnel;
+
+	iph = ip_hdr(skb);
+	tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex, tpi->flags,
+				  iph->saddr, iph->daddr, tpi->key);
+
+	if (tunnel) {
+		const struct iphdr *tnl_params;
+
+		if (__iptunnel_pull_header(skb, hdr_len, tpi->proto,
+					   raw_proto, false) < 0)
+			goto drop;
+
+		if (tunnel->dev->type != ARPHRD_NONE)
+			skb_pop_mac_header(skb);
+		else
+			skb_reset_mac_header(skb);
+
+		tnl_params = &tunnel->parms.iph;
+		if (tunnel->collect_md || tnl_params->daddr == 0) {
+			__be16 flags;
+			__be64 tun_id;
+
+			flags = tpi->flags & (TUNNEL_CSUM | TUNNEL_KEY);
+			tun_id = key32_to_tunnel_id(tpi->key);
+			tun_dst = ip_tun_rx_dst(skb, flags, tun_id, 0);
+			if (!tun_dst)
+				return PACKET_REJECT;
+		}
+
+		ip_tunnel_rcv(tunnel, skb, tpi, tun_dst, log_ecn_error);
+		return PACKET_RCVD;
+	}
+	return PACKET_NEXT;
+
+drop:
+	kfree_skb(skb);
+	return PACKET_RCVD;
+}
+
+static int ipgre_rcv(struct sk_buff *skb, const struct tnl_ptk_info *tpi,
+		     int hdr_len)
+{
+	struct net *net = dev_net(skb->dev);
+	struct ip_tunnel_net *itn;
+	int res;
+
+	if (tpi->proto == htons(ETH_P_TEB))
+		itn = net_generic(net, gre_tap_net_id);
+	else
+		itn = net_generic(net, ipgre_net_id);
+
+	res = __ipgre_rcv(skb, tpi, itn, hdr_len, false);
+	if (res == PACKET_NEXT && tpi->proto == htons(ETH_P_TEB)) {
+		/* ipgre tunnels in collect metadata mode should receive
+		 * also ETH_P_TEB traffic.
+		 */
+		itn = net_generic(net, ipgre_net_id);
+		res = __ipgre_rcv(skb, tpi, itn, hdr_len, true);
+	}
+	return res;
+}
+
+static int gre_rcv(struct sk_buff *skb)
+{
+	struct tnl_ptk_info tpi;
+	bool csum_err = false;
+	int hdr_len;
+
+#ifdef CONFIG_NET_IPGRE_BROADCAST
+	if (ipv4_is_multicast(ip_hdr(skb)->daddr)) {
+		/* Looped back packet, drop it! */
+		if (rt_is_output_route(skb_rtable(skb)))
+			goto drop;
+	}
+#endif
+
+	hdr_len = gre_parse_header(skb, &tpi, &csum_err, htons(ETH_P_IP), 0);
+	if (hdr_len < 0)
+		goto drop;
+
+	if (unlikely(tpi.proto == htons(ETH_P_ERSPAN) ||
+		     tpi.proto == htons(ETH_P_ERSPAN2))) {
+		if (erspan_rcv(skb, &tpi, hdr_len) == PACKET_RCVD)
+			return 0;
+		goto out;
+	}
+
+	if (ipgre_rcv(skb, &tpi, hdr_len) == PACKET_RCVD)
+		return 0;
+
+out:
+	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
+drop:
+	kfree_skb(skb);
+	return 0;
+}
+
+static void __gre_xmit(struct sk_buff *skb, struct net_device *dev,
+		       const struct iphdr *tnl_params,
+		       __be16 proto)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+	__be16 flags = tunnel->parms.o_flags;
+
+	/* Push GRE header. */
+	gre_build_header(skb, tunnel->tun_hlen,
+			 flags, proto, tunnel->parms.o_key,
+			 (flags & TUNNEL_SEQ) ? htonl(atomic_fetch_inc(&tunnel->o_seqno)) : 0);
+
+	ip_tunnel_xmit(skb, dev, tnl_params, tnl_params->protocol);
+}
+
+static int gre_handle_offloads(struct sk_buff *skb, bool csum)
+{
+	return iptunnel_handle_offloads(skb, csum ? SKB_GSO_GRE_CSUM : SKB_GSO_GRE);
+}
+
+static void gre_fb_xmit(struct sk_buff *skb, struct net_device *dev,
+			__be16 proto)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+	struct ip_tunnel_info *tun_info;
+	const struct ip_tunnel_key *key;
+	int tunnel_hlen;
+	__be16 flags;
+
+	tun_info = skb_tunnel_info(skb);
+	if (unlikely(!tun_info || !(tun_info->mode & IP_TUNNEL_INFO_TX) ||
+		     ip_tunnel_info_af(tun_info) != AF_INET))
+		goto err_free_skb;
+
+	key = &tun_info->key;
+	tunnel_hlen = gre_calc_hlen(key->tun_flags);
+
+	if (skb_cow_head(skb, dev->needed_headroom))
+		goto err_free_skb;
+
+	/* Push Tunnel header. */
+	if (gre_handle_offloads(skb, !!(tun_info->key.tun_flags & TUNNEL_CSUM)))
+		goto err_free_skb;
+
+	flags = tun_info->key.tun_flags &
+		(TUNNEL_CSUM | TUNNEL_KEY | TUNNEL_SEQ);
+	gre_build_header(skb, tunnel_hlen, flags, proto,
+			 tunnel_id_to_key32(tun_info->key.tun_id),
+			 (flags & TUNNEL_SEQ) ? htonl(atomic_fetch_inc(&tunnel->o_seqno)) : 0);
+
+	ip_md_tunnel_xmit(skb, dev, IPPROTO_GRE, tunnel_hlen);
+
+	return;
+
+err_free_skb:
+	kfree_skb(skb);
+	dev->stats.tx_dropped++;
+}
+
+static void erspan_fb_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+	struct ip_tunnel_info *tun_info;
+	const struct ip_tunnel_key *key;
+	struct erspan_metadata *md;
+	bool truncate = false;
+	__be16 proto;
+	int tunnel_hlen;
+	int version;
+	int nhoff;
+
+	tun_info = skb_tunnel_info(skb);
+	if (unlikely(!tun_info || !(tun_info->mode & IP_TUNNEL_INFO_TX) ||
+		     ip_tunnel_info_af(tun_info) != AF_INET))
+		goto err_free_skb;
+
+	key = &tun_info->key;
+	if (!(tun_info->key.tun_flags & TUNNEL_ERSPAN_OPT))
+		goto err_free_skb;
+	if (tun_info->options_len < sizeof(*md))
+		goto err_free_skb;
+	md = ip_tunnel_info_opts(tun_info);
+
+	/* ERSPAN has fixed 8 byte GRE header */
+	version = md->version;
+	tunnel_hlen = 8 + erspan_hdr_len(version);
+
+	if (skb_cow_head(skb, dev->needed_headroom))
+		goto err_free_skb;
+
+	if (gre_handle_offloads(skb, false))
+		goto err_free_skb;
+
+	if (skb->len > dev->mtu + dev->hard_header_len) {
+		pskb_trim(skb, dev->mtu + dev->hard_header_len);
+		truncate = true;
+	}
+
+	nhoff = skb_network_offset(skb);
+	if (skb->protocol == htons(ETH_P_IP) &&
+	    (ntohs(ip_hdr(skb)->tot_len) > skb->len - nhoff))
+		truncate = true;
+
+	if (skb->protocol == htons(ETH_P_IPV6)) {
+		int thoff;
+
+		if (skb_transport_header_was_set(skb))
+			thoff = skb_transport_offset(skb);
+		else
+			thoff = nhoff + sizeof(struct ipv6hdr);
+		if (ntohs(ipv6_hdr(skb)->payload_len) > skb->len - thoff)
+			truncate = true;
+	}
+
+	if (version == 1) {
+		erspan_build_header(skb, ntohl(tunnel_id_to_key32(key->tun_id)),
+				    ntohl(md->u.index), truncate, true);
+		proto = htons(ETH_P_ERSPAN);
+	} else if (version == 2) {
+		erspan_build_header_v2(skb,
+				       ntohl(tunnel_id_to_key32(key->tun_id)),
+				       md->u.md2.dir,
+				       get_hwid(&md->u.md2),
+				       truncate, true);
+		proto = htons(ETH_P_ERSPAN2);
+	} else {
+		goto err_free_skb;
+	}
+
+	gre_build_header(skb, 8, TUNNEL_SEQ,
+			 proto, 0, htonl(atomic_fetch_inc(&tunnel->o_seqno)));
+
+	ip_md_tunnel_xmit(skb, dev, IPPROTO_GRE, tunnel_hlen);
+
+	return;
+
+err_free_skb:
+	kfree_skb(skb);
+	dev->stats.tx_dropped++;
+}
+
+static int gre_fill_metadata_dst(struct net_device *dev, struct sk_buff *skb)
+{
+	struct ip_tunnel_info *info = skb_tunnel_info(skb);
+	const struct ip_tunnel_key *key;
+	struct rtable *rt;
+	struct flowi4 fl4;
+
+	if (ip_tunnel_info_af(info) != AF_INET)
+		return -EINVAL;
+
+	key = &info->key;
+	ip_tunnel_init_flow(&fl4, IPPROTO_GRE, key->u.ipv4.dst, key->u.ipv4.src,
+			    tunnel_id_to_key32(key->tun_id),
+			    key->tos & ~INET_ECN_MASK, 0, skb->mark,
+			    skb_get_hash(skb));
+	rt = ip_route_output_key(dev_net(dev), &fl4);
+	if (IS_ERR(rt))
+		return PTR_ERR(rt);
+
+	ip_rt_put(rt);
+	info->key.u.ipv4.src = fl4.saddr;
+	return 0;
+}
+
+static netdev_tx_t ipgre_xmit(struct sk_buff *skb,
+			      struct net_device *dev)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+	const struct iphdr *tnl_params;
+
+	if (!pskb_inet_may_pull(skb))
+		goto free_skb;
+
+	if (tunnel->collect_md) {
+		gre_fb_xmit(skb, dev, skb->protocol);
+		return NETDEV_TX_OK;
+	}
+
+	if (dev->header_ops) {
+		int pull_len = tunnel->hlen + sizeof(struct iphdr);
+
+		if (skb_cow_head(skb, 0))
+			goto free_skb;
+
+		tnl_params = (const struct iphdr *)skb->data;
+
+		if (!pskb_network_may_pull(skb, pull_len))
+			goto free_skb;
+
+		/* ip_tunnel_xmit() needs skb->data pointing to gre header. */
+		skb_pull(skb, pull_len);
+		skb_reset_mac_header(skb);
+
+		if (skb->ip_summed == CHECKSUM_PARTIAL &&
+		    skb_checksum_start(skb) < skb->data)
+			goto free_skb;
+	} else {
+		if (skb_cow_head(skb, dev->needed_headroom))
+			goto free_skb;
+
+		tnl_params = &tunnel->parms.iph;
+	}
+
+	if (gre_handle_offloads(skb, !!(tunnel->parms.o_flags & TUNNEL_CSUM)))
+		goto free_skb;
+
+	__gre_xmit(skb, dev, tnl_params, skb->protocol);
+	return NETDEV_TX_OK;
+
+free_skb:
+	kfree_skb(skb);
+	dev->stats.tx_dropped++;
+	return NETDEV_TX_OK;
+}
+
+static netdev_tx_t erspan_xmit(struct sk_buff *skb,
+			       struct net_device *dev)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+	bool truncate = false;
+	__be16 proto;
+
+	if (!pskb_inet_may_pull(skb))
+		goto free_skb;
+
+	if (tunnel->collect_md) {
+		erspan_fb_xmit(skb, dev);
+		return NETDEV_TX_OK;
+	}
+
+	if (gre_handle_offloads(skb, false))
+		goto free_skb;
+
+	if (skb_cow_head(skb, dev->needed_headroom))
+		goto free_skb;
+
+	if (skb->len > dev->mtu + dev->hard_header_len) {
+		pskb_trim(skb, dev->mtu + dev->hard_header_len);
+		truncate = true;
+	}
+
+	/* Push ERSPAN header */
+	if (tunnel->erspan_ver == 0) {
+		proto = htons(ETH_P_ERSPAN);
+		tunnel->parms.o_flags &= ~TUNNEL_SEQ;
+	} else if (tunnel->erspan_ver == 1) {
+		erspan_build_header(skb, ntohl(tunnel->parms.o_key),
+				    tunnel->index,
+				    truncate, true);
+		proto = htons(ETH_P_ERSPAN);
+	} else if (tunnel->erspan_ver == 2) {
+		erspan_build_header_v2(skb, ntohl(tunnel->parms.o_key),
+				       tunnel->dir, tunnel->hwid,
+				       truncate, true);
+		proto = htons(ETH_P_ERSPAN2);
+	} else {
+		goto free_skb;
+	}
+
+	tunnel->parms.o_flags &= ~TUNNEL_KEY;
+	__gre_xmit(skb, dev, &tunnel->parms.iph, proto);
+	return NETDEV_TX_OK;
+
+free_skb:
+	kfree_skb(skb);
+	dev->stats.tx_dropped++;
+	return NETDEV_TX_OK;
+}
+
+static netdev_tx_t gre_tap_xmit(struct sk_buff *skb,
+				struct net_device *dev)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+
+	if (!pskb_inet_may_pull(skb))
+		goto free_skb;
+
+	if (tunnel->collect_md) {
+		gre_fb_xmit(skb, dev, htons(ETH_P_TEB));
+		return NETDEV_TX_OK;
+	}
+
+	if (gre_handle_offloads(skb, !!(tunnel->parms.o_flags & TUNNEL_CSUM)))
+		goto free_skb;
+
+	if (skb_cow_head(skb, dev->needed_headroom))
+		goto free_skb;
+
+	__gre_xmit(skb, dev, &tunnel->parms.iph, htons(ETH_P_TEB));
+	return NETDEV_TX_OK;
+
+free_skb:
+	kfree_skb(skb);
+	dev->stats.tx_dropped++;
+	return NETDEV_TX_OK;
+}
+
+static void ipgre_link_update(struct net_device *dev, bool set_mtu)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+	int len;
+
+	len = tunnel->tun_hlen;
+	tunnel->tun_hlen = gre_calc_hlen(tunnel->parms.o_flags);
+	len = tunnel->tun_hlen - len;
+	tunnel->hlen = tunnel->hlen + len;
+
+	if (dev->header_ops)
+		dev->hard_header_len += len;
+	else
+		dev->needed_headroom += len;
+
+	if (set_mtu)
+		dev->mtu = max_t(int, dev->mtu - len, 68);
+
+	if (!(tunnel->parms.o_flags & TUNNEL_SEQ)) {
+		if (!(tunnel->parms.o_flags & TUNNEL_CSUM) ||
+		    tunnel->encap.type == TUNNEL_ENCAP_NONE) {
+			dev->features |= NETIF_F_GSO_SOFTWARE;
+			dev->hw_features |= NETIF_F_GSO_SOFTWARE;
+		} else {
+			dev->features &= ~NETIF_F_GSO_SOFTWARE;
+			dev->hw_features &= ~NETIF_F_GSO_SOFTWARE;
+		}
+		dev->features |= NETIF_F_LLTX;
+	} else {
+		dev->hw_features &= ~NETIF_F_GSO_SOFTWARE;
+		dev->features &= ~(NETIF_F_LLTX | NETIF_F_GSO_SOFTWARE);
+	}
+}
+
+static int ipgre_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm *p,
+			    int cmd)
+{
+	int err;
+
+	if (cmd == SIOCADDTUNNEL || cmd == SIOCCHGTUNNEL) {
+		if (p->iph.version != 4 || p->iph.protocol != IPPROTO_GRE ||
+		    p->iph.ihl != 5 || (p->iph.frag_off & htons(~IP_DF)) ||
+		    ((p->i_flags | p->o_flags) & (GRE_VERSION | GRE_ROUTING)))
+			return -EINVAL;
+	}
+
+	p->i_flags = gre_flags_to_tnl_flags(p->i_flags);
+	p->o_flags = gre_flags_to_tnl_flags(p->o_flags);
+
+	err = ip_tunnel_ctl(dev, p, cmd);
+	if (err)
+		return err;
+
+	if (cmd == SIOCCHGTUNNEL) {
+		struct ip_tunnel *t = netdev_priv(dev);
+
+		t->parms.i_flags = p->i_flags;
+		t->parms.o_flags = p->o_flags;
+
+		if (strcmp(dev->rtnl_link_ops->kind, "erspan"))
+			ipgre_link_update(dev, true);
+	}
+
+	p->i_flags = gre_tnl_flags_to_gre_flags(p->i_flags);
+	p->o_flags = gre_tnl_flags_to_gre_flags(p->o_flags);
+	return 0;
+}
+
+/* Nice toy. Unfortunately, useless in real life :-)
+   It allows to construct virtual multiprotocol broadcast "LAN"
+   over the Internet, provided multicast routing is tuned.
+
+
+   I have no idea was this bicycle invented before me,
+   so that I had to set ARPHRD_IPGRE to a random value.
+   I have an impression, that Cisco could make something similar,
+   but this feature is apparently missing in IOS<=11.2(8).
+
+   I set up 10.66.66/24 and fec0:6666:6666::0/96 as virtual networks
+   with broadcast 224.66.66.66. If you have access to mbone, play with me :-)
+
+   ping -t 255 224.66.66.66
+
+   If nobody answers, mbone does not work.
+
+   ip tunnel add Universe mode gre remote 224.66.66.66 local <Your_real_addr> ttl 255
+   ip addr add 10.66.66.<somewhat>/24 dev Universe
+   ifconfig Universe up
+   ifconfig Universe add fe80::<Your_real_addr>/10
+   ifconfig Universe add fec0:6666:6666::<Your_real_addr>/96
+   ftp 10.66.66.66
+   ...
+   ftp fec0:6666:6666::193.233.7.65
+   ...
+ */
+static int ipgre_header(struct sk_buff *skb, struct net_device *dev,
+			unsigned short type,
+			const void *daddr, const void *saddr, unsigned int len)
+{
+	struct ip_tunnel *t = netdev_priv(dev);
+	struct iphdr *iph;
+	struct gre_base_hdr *greh;
+
+	iph = skb_push(skb, t->hlen + sizeof(*iph));
+	greh = (struct gre_base_hdr *)(iph+1);
+	greh->flags = gre_tnl_flags_to_gre_flags(t->parms.o_flags);
+	greh->protocol = htons(type);
+
+	memcpy(iph, &t->parms.iph, sizeof(struct iphdr));
+
+	/* Set the source hardware address. */
+	if (saddr)
+		memcpy(&iph->saddr, saddr, 4);
+	if (daddr)
+		memcpy(&iph->daddr, daddr, 4);
+	if (iph->daddr)
+		return t->hlen + sizeof(*iph);
+
+	return -(t->hlen + sizeof(*iph));
+}
+
+static int ipgre_header_parse(const struct sk_buff *skb, unsigned char *haddr)
+{
+	const struct iphdr *iph = (const struct iphdr *) skb_mac_header(skb);
+	memcpy(haddr, &iph->saddr, 4);
+	return 4;
+}
+
+static const struct header_ops ipgre_header_ops = {
+	.create	= ipgre_header,
+	.parse	= ipgre_header_parse,
+};
+
+#ifdef CONFIG_NET_IPGRE_BROADCAST
+static int ipgre_open(struct net_device *dev)
+{
+	struct ip_tunnel *t = netdev_priv(dev);
+
+	if (ipv4_is_multicast(t->parms.iph.daddr)) {
+		struct flowi4 fl4;
+		struct rtable *rt;
+
+		rt = ip_route_output_gre(t->net, &fl4,
+					 t->parms.iph.daddr,
+					 t->parms.iph.saddr,
+					 t->parms.o_key,
+					 RT_TOS(t->parms.iph.tos),
+					 t->parms.link);
+		if (IS_ERR(rt))
+			return -EADDRNOTAVAIL;
+		dev = rt->dst.dev;
+		ip_rt_put(rt);
+		if (!__in_dev_get_rtnl(dev))
+			return -EADDRNOTAVAIL;
+		t->mlink = dev->ifindex;
+		ip_mc_inc_group(__in_dev_get_rtnl(dev), t->parms.iph.daddr);
+	}
+	return 0;
+}
+
+static int ipgre_close(struct net_device *dev)
+{
+	struct ip_tunnel *t = netdev_priv(dev);
+
+	if (ipv4_is_multicast(t->parms.iph.daddr) && t->mlink) {
+		struct in_device *in_dev;
+		in_dev = inetdev_by_index(t->net, t->mlink);
+		if (in_dev)
+			ip_mc_dec_group(in_dev, t->parms.iph.daddr);
+	}
+	return 0;
+}
+#endif
+
+static const struct net_device_ops ipgre_netdev_ops = {
+	.ndo_init		= ipgre_tunnel_init,
+	.ndo_uninit		= ip_tunnel_uninit,
+#ifdef CONFIG_NET_IPGRE_BROADCAST
+	.ndo_open		= ipgre_open,
+	.ndo_stop		= ipgre_close,
+#endif
+	.ndo_start_xmit		= ipgre_xmit,
+	.ndo_do_ioctl		= ip_tunnel_ioctl,
+	.ndo_change_mtu		= ip_tunnel_change_mtu,
+	.ndo_get_stats64	= ip_tunnel_get_stats64,
+	.ndo_get_iflink		= ip_tunnel_get_iflink,
+	.ndo_tunnel_ctl		= ipgre_tunnel_ctl,
+};
+
+#define GRE_FEATURES (NETIF_F_SG |		\
+		      NETIF_F_FRAGLIST |	\
+		      NETIF_F_HIGHDMA |		\
+		      NETIF_F_HW_CSUM)
+
+static void ipgre_tunnel_setup(struct net_device *dev)
+{
+	dev->netdev_ops		= &ipgre_netdev_ops;
+	dev->type		= ARPHRD_IPGRE;
+	ip_tunnel_setup(dev, ipgre_net_id);
+}
+
+static void __gre_tunnel_init(struct net_device *dev)
+{
+	struct ip_tunnel *tunnel;
+
+	tunnel = netdev_priv(dev);
+	tunnel->tun_hlen = gre_calc_hlen(tunnel->parms.o_flags);
+	tunnel->parms.iph.protocol = IPPROTO_GRE;
+
+	tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen;
+	dev->needed_headroom = tunnel->hlen + sizeof(tunnel->parms.iph);
+
+	dev->features		|= GRE_FEATURES;
+	dev->hw_features	|= GRE_FEATURES;
+
+	if (!(tunnel->parms.o_flags & TUNNEL_SEQ)) {
+		/* TCP offload with GRE SEQ is not supported, nor
+		 * can we support 2 levels of outer headers requiring
+		 * an update.
+		 */
+		if (!(tunnel->parms.o_flags & TUNNEL_CSUM) ||
+		    (tunnel->encap.type == TUNNEL_ENCAP_NONE)) {
+			dev->features    |= NETIF_F_GSO_SOFTWARE;
+			dev->hw_features |= NETIF_F_GSO_SOFTWARE;
+		}
+
+		/* Can use a lockless transmit, unless we generate
+		 * output sequences
+		 */
+		dev->features |= NETIF_F_LLTX;
+	}
+}
+
+static int ipgre_tunnel_init(struct net_device *dev)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+	struct iphdr *iph = &tunnel->parms.iph;
+
+	__gre_tunnel_init(dev);
+
+	memcpy(dev->dev_addr, &iph->saddr, 4);
+	memcpy(dev->broadcast, &iph->daddr, 4);
+
+	dev->flags		= IFF_NOARP;
+	netif_keep_dst(dev);
+	dev->addr_len		= 4;
+
+	if (iph->daddr && !tunnel->collect_md) {
+#ifdef CONFIG_NET_IPGRE_BROADCAST
+		if (ipv4_is_multicast(iph->daddr)) {
+			if (!iph->saddr)
+				return -EINVAL;
+			dev->flags = IFF_BROADCAST;
+			dev->header_ops = &ipgre_header_ops;
+			dev->hard_header_len = tunnel->hlen + sizeof(*iph);
+			dev->needed_headroom = 0;
+		}
+#endif
+	} else if (!tunnel->collect_md) {
+		dev->header_ops = &ipgre_header_ops;
+		dev->hard_header_len = tunnel->hlen + sizeof(*iph);
+		dev->needed_headroom = 0;
+	}
+
+	return ip_tunnel_init(dev);
+}
+
+static const struct gre_protocol ipgre_protocol = {
+	.handler     = gre_rcv,
+	.err_handler = gre_err,
+};
+
+static int __net_init ipgre_init_net(struct net *net)
+{
+	return ip_tunnel_init_net(net, ipgre_net_id, &ipgre_link_ops, NULL);
+}
+
+static void __net_exit ipgre_exit_batch_net(struct list_head *list_net)
+{
+	ip_tunnel_delete_nets(list_net, ipgre_net_id, &ipgre_link_ops);
+}
+
+static struct pernet_operations ipgre_net_ops = {
+	.init = ipgre_init_net,
+	.exit_batch = ipgre_exit_batch_net,
+	.id   = &ipgre_net_id,
+	.size = sizeof(struct ip_tunnel_net),
+};
+
+static int ipgre_tunnel_validate(struct nlattr *tb[], struct nlattr *data[],
+				 struct netlink_ext_ack *extack)
+{
+	__be16 flags;
+
+	if (!data)
+		return 0;
+
+	flags = 0;
+	if (data[IFLA_GRE_IFLAGS])
+		flags |= nla_get_be16(data[IFLA_GRE_IFLAGS]);
+	if (data[IFLA_GRE_OFLAGS])
+		flags |= nla_get_be16(data[IFLA_GRE_OFLAGS]);
+	if (flags & (GRE_VERSION|GRE_ROUTING))
+		return -EINVAL;
+
+	if (data[IFLA_GRE_COLLECT_METADATA] &&
+	    data[IFLA_GRE_ENCAP_TYPE] &&
+	    nla_get_u16(data[IFLA_GRE_ENCAP_TYPE]) != TUNNEL_ENCAP_NONE)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int ipgre_tap_validate(struct nlattr *tb[], struct nlattr *data[],
+			      struct netlink_ext_ack *extack)
+{
+	__be32 daddr;
+
+	if (tb[IFLA_ADDRESS]) {
+		if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
+			return -EINVAL;
+		if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
+			return -EADDRNOTAVAIL;
+	}
+
+	if (!data)
+		goto out;
+
+	if (data[IFLA_GRE_REMOTE]) {
+		memcpy(&daddr, nla_data(data[IFLA_GRE_REMOTE]), 4);
+		if (!daddr)
+			return -EINVAL;
+	}
+
+out:
+	return ipgre_tunnel_validate(tb, data, extack);
+}
+
+static int erspan_validate(struct nlattr *tb[], struct nlattr *data[],
+			   struct netlink_ext_ack *extack)
+{
+	__be16 flags = 0;
+	int ret;
+
+	if (!data)
+		return 0;
+
+	ret = ipgre_tap_validate(tb, data, extack);
+	if (ret)
+		return ret;
+
+	if (data[IFLA_GRE_ERSPAN_VER] &&
+	    nla_get_u8(data[IFLA_GRE_ERSPAN_VER]) == 0)
+		return 0;
+
+	/* ERSPAN type II/III should only have GRE sequence and key flag */
+	if (data[IFLA_GRE_OFLAGS])
+		flags |= nla_get_be16(data[IFLA_GRE_OFLAGS]);
+	if (data[IFLA_GRE_IFLAGS])
+		flags |= nla_get_be16(data[IFLA_GRE_IFLAGS]);
+	if (!data[IFLA_GRE_COLLECT_METADATA] &&
+	    flags != (GRE_SEQ | GRE_KEY))
+		return -EINVAL;
+
+	/* ERSPAN Session ID only has 10-bit. Since we reuse
+	 * 32-bit key field as ID, check it's range.
+	 */
+	if (data[IFLA_GRE_IKEY] &&
+	    (ntohl(nla_get_be32(data[IFLA_GRE_IKEY])) & ~ID_MASK))
+		return -EINVAL;
+
+	if (data[IFLA_GRE_OKEY] &&
+	    (ntohl(nla_get_be32(data[IFLA_GRE_OKEY])) & ~ID_MASK))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int ipgre_netlink_parms(struct net_device *dev,
+				struct nlattr *data[],
+				struct nlattr *tb[],
+				struct ip_tunnel_parm *parms,
+				__u32 *fwmark)
+{
+	struct ip_tunnel *t = netdev_priv(dev);
+
+	memset(parms, 0, sizeof(*parms));
+
+	parms->iph.protocol = IPPROTO_GRE;
+
+	if (!data)
+		return 0;
+
+	if (data[IFLA_GRE_LINK])
+		parms->link = nla_get_u32(data[IFLA_GRE_LINK]);
+
+	if (data[IFLA_GRE_IFLAGS])
+		parms->i_flags = gre_flags_to_tnl_flags(nla_get_be16(data[IFLA_GRE_IFLAGS]));
+
+	if (data[IFLA_GRE_OFLAGS])
+		parms->o_flags = gre_flags_to_tnl_flags(nla_get_be16(data[IFLA_GRE_OFLAGS]));
+
+	if (data[IFLA_GRE_IKEY])
+		parms->i_key = nla_get_be32(data[IFLA_GRE_IKEY]);
+
+	if (data[IFLA_GRE_OKEY])
+		parms->o_key = nla_get_be32(data[IFLA_GRE_OKEY]);
+
+	if (data[IFLA_GRE_LOCAL])
+		parms->iph.saddr = nla_get_in_addr(data[IFLA_GRE_LOCAL]);
+
+	if (data[IFLA_GRE_REMOTE])
+		parms->iph.daddr = nla_get_in_addr(data[IFLA_GRE_REMOTE]);
+
+	if (data[IFLA_GRE_TTL])
+		parms->iph.ttl = nla_get_u8(data[IFLA_GRE_TTL]);
+
+	if (data[IFLA_GRE_TOS])
+		parms->iph.tos = nla_get_u8(data[IFLA_GRE_TOS]);
+
+	if (!data[IFLA_GRE_PMTUDISC] || nla_get_u8(data[IFLA_GRE_PMTUDISC])) {
+		if (t->ignore_df)
+			return -EINVAL;
+		parms->iph.frag_off = htons(IP_DF);
+	}
+
+	if (data[IFLA_GRE_COLLECT_METADATA]) {
+		t->collect_md = true;
+		if (dev->type == ARPHRD_IPGRE)
+			dev->type = ARPHRD_NONE;
+	}
+
+	if (data[IFLA_GRE_IGNORE_DF]) {
+		if (nla_get_u8(data[IFLA_GRE_IGNORE_DF])
+		  && (parms->iph.frag_off & htons(IP_DF)))
+			return -EINVAL;
+		t->ignore_df = !!nla_get_u8(data[IFLA_GRE_IGNORE_DF]);
+	}
+
+	if (data[IFLA_GRE_FWMARK])
+		*fwmark = nla_get_u32(data[IFLA_GRE_FWMARK]);
+
+	return 0;
+}
+
+static int erspan_netlink_parms(struct net_device *dev,
+				struct nlattr *data[],
+				struct nlattr *tb[],
+				struct ip_tunnel_parm *parms,
+				__u32 *fwmark)
+{
+	struct ip_tunnel *t = netdev_priv(dev);
+	int err;
+
+	err = ipgre_netlink_parms(dev, data, tb, parms, fwmark);
+	if (err)
+		return err;
+	if (!data)
+		return 0;
+
+	if (data[IFLA_GRE_ERSPAN_VER]) {
+		t->erspan_ver = nla_get_u8(data[IFLA_GRE_ERSPAN_VER]);
+
+		if (t->erspan_ver > 2)
+			return -EINVAL;
+	}
+
+	if (t->erspan_ver == 1) {
+		if (data[IFLA_GRE_ERSPAN_INDEX]) {
+			t->index = nla_get_u32(data[IFLA_GRE_ERSPAN_INDEX]);
+			if (t->index & ~INDEX_MASK)
+				return -EINVAL;
+		}
+	} else if (t->erspan_ver == 2) {
+		if (data[IFLA_GRE_ERSPAN_DIR]) {
+			t->dir = nla_get_u8(data[IFLA_GRE_ERSPAN_DIR]);
+			if (t->dir & ~(DIR_MASK >> DIR_OFFSET))
+				return -EINVAL;
+		}
+		if (data[IFLA_GRE_ERSPAN_HWID]) {
+			t->hwid = nla_get_u16(data[IFLA_GRE_ERSPAN_HWID]);
+			if (t->hwid & ~(HWID_MASK >> HWID_OFFSET))
+				return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+/* This function returns true when ENCAP attributes are present in the nl msg */
+static bool ipgre_netlink_encap_parms(struct nlattr *data[],
+				      struct ip_tunnel_encap *ipencap)
+{
+	bool ret = false;
+
+	memset(ipencap, 0, sizeof(*ipencap));
+
+	if (!data)
+		return ret;
+
+	if (data[IFLA_GRE_ENCAP_TYPE]) {
+		ret = true;
+		ipencap->type = nla_get_u16(data[IFLA_GRE_ENCAP_TYPE]);
+	}
+
+	if (data[IFLA_GRE_ENCAP_FLAGS]) {
+		ret = true;
+		ipencap->flags = nla_get_u16(data[IFLA_GRE_ENCAP_FLAGS]);
+	}
+
+	if (data[IFLA_GRE_ENCAP_SPORT]) {
+		ret = true;
+		ipencap->sport = nla_get_be16(data[IFLA_GRE_ENCAP_SPORT]);
+	}
+
+	if (data[IFLA_GRE_ENCAP_DPORT]) {
+		ret = true;
+		ipencap->dport = nla_get_be16(data[IFLA_GRE_ENCAP_DPORT]);
+	}
+
+	return ret;
+}
+
+static int gre_tap_init(struct net_device *dev)
+{
+	__gre_tunnel_init(dev);
+	dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
+	netif_keep_dst(dev);
+
+	return ip_tunnel_init(dev);
+}
+
+static const struct net_device_ops gre_tap_netdev_ops = {
+	.ndo_init		= gre_tap_init,
+	.ndo_uninit		= ip_tunnel_uninit,
+	.ndo_start_xmit		= gre_tap_xmit,
+	.ndo_set_mac_address 	= eth_mac_addr,
+	.ndo_validate_addr	= eth_validate_addr,
+	.ndo_change_mtu		= ip_tunnel_change_mtu,
+	.ndo_get_stats64	= ip_tunnel_get_stats64,
+	.ndo_get_iflink		= ip_tunnel_get_iflink,
+	.ndo_fill_metadata_dst	= gre_fill_metadata_dst,
+};
+
+static int erspan_tunnel_init(struct net_device *dev)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+
+	if (tunnel->erspan_ver == 0)
+		tunnel->tun_hlen = 4; /* 4-byte GRE hdr. */
+	else
+		tunnel->tun_hlen = 8; /* 8-byte GRE hdr. */
+
+	tunnel->parms.iph.protocol = IPPROTO_GRE;
+	tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen +
+		       erspan_hdr_len(tunnel->erspan_ver);
+
+	dev->features		|= GRE_FEATURES;
+	dev->hw_features	|= GRE_FEATURES;
+	dev->priv_flags		|= IFF_LIVE_ADDR_CHANGE;
+	netif_keep_dst(dev);
+
+	return ip_tunnel_init(dev);
+}
+
+static const struct net_device_ops erspan_netdev_ops = {
+	.ndo_init		= erspan_tunnel_init,
+	.ndo_uninit		= ip_tunnel_uninit,
+	.ndo_start_xmit		= erspan_xmit,
+	.ndo_set_mac_address	= eth_mac_addr,
+	.ndo_validate_addr	= eth_validate_addr,
+	.ndo_change_mtu		= ip_tunnel_change_mtu,
+	.ndo_get_stats64	= ip_tunnel_get_stats64,
+	.ndo_get_iflink		= ip_tunnel_get_iflink,
+	.ndo_fill_metadata_dst	= gre_fill_metadata_dst,
+};
+
+static void ipgre_tap_setup(struct net_device *dev)
+{
+	ether_setup(dev);
+	dev->max_mtu = 0;
+	dev->netdev_ops	= &gre_tap_netdev_ops;
+	dev->priv_flags &= ~IFF_TX_SKB_SHARING;
+	dev->priv_flags	|= IFF_LIVE_ADDR_CHANGE;
+	ip_tunnel_setup(dev, gre_tap_net_id);
+}
+
+static int
+ipgre_newlink_encap_setup(struct net_device *dev, struct nlattr *data[])
+{
+	struct ip_tunnel_encap ipencap;
+
+	if (ipgre_netlink_encap_parms(data, &ipencap)) {
+		struct ip_tunnel *t = netdev_priv(dev);
+		int err = ip_tunnel_encap_setup(t, &ipencap);
+
+		if (err < 0)
+			return err;
+	}
+
+	return 0;
+}
+
+static int ipgre_newlink(struct net *src_net, struct net_device *dev,
+			 struct nlattr *tb[], struct nlattr *data[],
+			 struct netlink_ext_ack *extack)
+{
+	struct ip_tunnel_parm p;
+	__u32 fwmark = 0;
+	int err;
+
+	err = ipgre_newlink_encap_setup(dev, data);
+	if (err)
+		return err;
+
+	err = ipgre_netlink_parms(dev, data, tb, &p, &fwmark);
+	if (err < 0)
+		return err;
+	return ip_tunnel_newlink(dev, tb, &p, fwmark);
+}
+
+static int erspan_newlink(struct net *src_net, struct net_device *dev,
+			  struct nlattr *tb[], struct nlattr *data[],
+			  struct netlink_ext_ack *extack)
+{
+	struct ip_tunnel_parm p;
+	__u32 fwmark = 0;
+	int err;
+
+	err = ipgre_newlink_encap_setup(dev, data);
+	if (err)
+		return err;
+
+	err = erspan_netlink_parms(dev, data, tb, &p, &fwmark);
+	if (err)
+		return err;
+	return ip_tunnel_newlink(dev, tb, &p, fwmark);
+}
+
+static int ipgre_changelink(struct net_device *dev, struct nlattr *tb[],
+			    struct nlattr *data[],
+			    struct netlink_ext_ack *extack)
+{
+	struct ip_tunnel *t = netdev_priv(dev);
+	__u32 fwmark = t->fwmark;
+	struct ip_tunnel_parm p;
+	int err;
+
+	err = ipgre_newlink_encap_setup(dev, data);
+	if (err)
+		return err;
+
+	err = ipgre_netlink_parms(dev, data, tb, &p, &fwmark);
+	if (err < 0)
+		return err;
+
+	err = ip_tunnel_changelink(dev, tb, &p, fwmark);
+	if (err < 0)
+		return err;
+
+	t->parms.i_flags = p.i_flags;
+	t->parms.o_flags = p.o_flags;
+
+	ipgre_link_update(dev, !tb[IFLA_MTU]);
+
+	return 0;
+}
+
+static int erspan_changelink(struct net_device *dev, struct nlattr *tb[],
+			     struct nlattr *data[],
+			     struct netlink_ext_ack *extack)
+{
+	struct ip_tunnel *t = netdev_priv(dev);
+	__u32 fwmark = t->fwmark;
+	struct ip_tunnel_parm p;
+	int err;
+
+	err = ipgre_newlink_encap_setup(dev, data);
+	if (err)
+		return err;
+
+	err = erspan_netlink_parms(dev, data, tb, &p, &fwmark);
+	if (err < 0)
+		return err;
+
+	err = ip_tunnel_changelink(dev, tb, &p, fwmark);
+	if (err < 0)
+		return err;
+
+	t->parms.i_flags = p.i_flags;
+	t->parms.o_flags = p.o_flags;
+
+	return 0;
+}
+
+static size_t ipgre_get_size(const struct net_device *dev)
+{
+	return
+		/* IFLA_GRE_LINK */
+		nla_total_size(4) +
+		/* IFLA_GRE_IFLAGS */
+		nla_total_size(2) +
+		/* IFLA_GRE_OFLAGS */
+		nla_total_size(2) +
+		/* IFLA_GRE_IKEY */
+		nla_total_size(4) +
+		/* IFLA_GRE_OKEY */
+		nla_total_size(4) +
+		/* IFLA_GRE_LOCAL */
+		nla_total_size(4) +
+		/* IFLA_GRE_REMOTE */
+		nla_total_size(4) +
+		/* IFLA_GRE_TTL */
+		nla_total_size(1) +
+		/* IFLA_GRE_TOS */
+		nla_total_size(1) +
+		/* IFLA_GRE_PMTUDISC */
+		nla_total_size(1) +
+		/* IFLA_GRE_ENCAP_TYPE */
+		nla_total_size(2) +
+		/* IFLA_GRE_ENCAP_FLAGS */
+		nla_total_size(2) +
+		/* IFLA_GRE_ENCAP_SPORT */
+		nla_total_size(2) +
+		/* IFLA_GRE_ENCAP_DPORT */
+		nla_total_size(2) +
+		/* IFLA_GRE_COLLECT_METADATA */
+		nla_total_size(0) +
+		/* IFLA_GRE_IGNORE_DF */
+		nla_total_size(1) +
+		/* IFLA_GRE_FWMARK */
+		nla_total_size(4) +
+		/* IFLA_GRE_ERSPAN_INDEX */
+		nla_total_size(4) +
+		/* IFLA_GRE_ERSPAN_VER */
+		nla_total_size(1) +
+		/* IFLA_GRE_ERSPAN_DIR */
+		nla_total_size(1) +
+		/* IFLA_GRE_ERSPAN_HWID */
+		nla_total_size(2) +
+		0;
+}
+
+static int ipgre_fill_info(struct sk_buff *skb, const struct net_device *dev)
+{
+	struct ip_tunnel *t = netdev_priv(dev);
+	struct ip_tunnel_parm *p = &t->parms;
+	__be16 o_flags = p->o_flags;
+
+	if (nla_put_u32(skb, IFLA_GRE_LINK, p->link) ||
+	    nla_put_be16(skb, IFLA_GRE_IFLAGS,
+			 gre_tnl_flags_to_gre_flags(p->i_flags)) ||
+	    nla_put_be16(skb, IFLA_GRE_OFLAGS,
+			 gre_tnl_flags_to_gre_flags(o_flags)) ||
+	    nla_put_be32(skb, IFLA_GRE_IKEY, p->i_key) ||
+	    nla_put_be32(skb, IFLA_GRE_OKEY, p->o_key) ||
+	    nla_put_in_addr(skb, IFLA_GRE_LOCAL, p->iph.saddr) ||
+	    nla_put_in_addr(skb, IFLA_GRE_REMOTE, p->iph.daddr) ||
+	    nla_put_u8(skb, IFLA_GRE_TTL, p->iph.ttl) ||
+	    nla_put_u8(skb, IFLA_GRE_TOS, p->iph.tos) ||
+	    nla_put_u8(skb, IFLA_GRE_PMTUDISC,
+		       !!(p->iph.frag_off & htons(IP_DF))) ||
+	    nla_put_u32(skb, IFLA_GRE_FWMARK, t->fwmark))
+		goto nla_put_failure;
+
+	if (nla_put_u16(skb, IFLA_GRE_ENCAP_TYPE,
+			t->encap.type) ||
+	    nla_put_be16(skb, IFLA_GRE_ENCAP_SPORT,
+			 t->encap.sport) ||
+	    nla_put_be16(skb, IFLA_GRE_ENCAP_DPORT,
+			 t->encap.dport) ||
+	    nla_put_u16(skb, IFLA_GRE_ENCAP_FLAGS,
+			t->encap.flags))
+		goto nla_put_failure;
+
+	if (nla_put_u8(skb, IFLA_GRE_IGNORE_DF, t->ignore_df))
+		goto nla_put_failure;
+
+	if (t->collect_md) {
+		if (nla_put_flag(skb, IFLA_GRE_COLLECT_METADATA))
+			goto nla_put_failure;
+	}
+
+	return 0;
+
+nla_put_failure:
+	return -EMSGSIZE;
+}
+
+static int erspan_fill_info(struct sk_buff *skb, const struct net_device *dev)
+{
+	struct ip_tunnel *t = netdev_priv(dev);
+
+	if (t->erspan_ver <= 2) {
+		if (t->erspan_ver != 0 && !t->collect_md)
+			t->parms.o_flags |= TUNNEL_KEY;
+
+		if (nla_put_u8(skb, IFLA_GRE_ERSPAN_VER, t->erspan_ver))
+			goto nla_put_failure;
+
+		if (t->erspan_ver == 1) {
+			if (nla_put_u32(skb, IFLA_GRE_ERSPAN_INDEX, t->index))
+				goto nla_put_failure;
+		} else if (t->erspan_ver == 2) {
+			if (nla_put_u8(skb, IFLA_GRE_ERSPAN_DIR, t->dir))
+				goto nla_put_failure;
+			if (nla_put_u16(skb, IFLA_GRE_ERSPAN_HWID, t->hwid))
+				goto nla_put_failure;
+		}
+	}
+
+	return ipgre_fill_info(skb, dev);
+
+nla_put_failure:
+	return -EMSGSIZE;
+}
+
+static void erspan_setup(struct net_device *dev)
+{
+	struct ip_tunnel *t = netdev_priv(dev);
+
+	ether_setup(dev);
+	dev->max_mtu = 0;
+	dev->netdev_ops = &erspan_netdev_ops;
+	dev->priv_flags &= ~IFF_TX_SKB_SHARING;
+	dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
+	ip_tunnel_setup(dev, erspan_net_id);
+	t->erspan_ver = 1;
+}
+
+static const struct nla_policy ipgre_policy[IFLA_GRE_MAX + 1] = {
+	[IFLA_GRE_LINK]		= { .type = NLA_U32 },
+	[IFLA_GRE_IFLAGS]	= { .type = NLA_U16 },
+	[IFLA_GRE_OFLAGS]	= { .type = NLA_U16 },
+	[IFLA_GRE_IKEY]		= { .type = NLA_U32 },
+	[IFLA_GRE_OKEY]		= { .type = NLA_U32 },
+	[IFLA_GRE_LOCAL]	= { .len = sizeof_field(struct iphdr, saddr) },
+	[IFLA_GRE_REMOTE]	= { .len = sizeof_field(struct iphdr, daddr) },
+	[IFLA_GRE_TTL]		= { .type = NLA_U8 },
+	[IFLA_GRE_TOS]		= { .type = NLA_U8 },
+	[IFLA_GRE_PMTUDISC]	= { .type = NLA_U8 },
+	[IFLA_GRE_ENCAP_TYPE]	= { .type = NLA_U16 },
+	[IFLA_GRE_ENCAP_FLAGS]	= { .type = NLA_U16 },
+	[IFLA_GRE_ENCAP_SPORT]	= { .type = NLA_U16 },
+	[IFLA_GRE_ENCAP_DPORT]	= { .type = NLA_U16 },
+	[IFLA_GRE_COLLECT_METADATA]	= { .type = NLA_FLAG },
+	[IFLA_GRE_IGNORE_DF]	= { .type = NLA_U8 },
+	[IFLA_GRE_FWMARK]	= { .type = NLA_U32 },
+	[IFLA_GRE_ERSPAN_INDEX]	= { .type = NLA_U32 },
+	[IFLA_GRE_ERSPAN_VER]	= { .type = NLA_U8 },
+	[IFLA_GRE_ERSPAN_DIR]	= { .type = NLA_U8 },
+	[IFLA_GRE_ERSPAN_HWID]	= { .type = NLA_U16 },
+};
+
+static struct rtnl_link_ops ipgre_link_ops __read_mostly = {
+	.kind		= "gre",
+	.maxtype	= IFLA_GRE_MAX,
+	.policy		= ipgre_policy,
+	.priv_size	= sizeof(struct ip_tunnel),
+	.setup		= ipgre_tunnel_setup,
+	.validate	= ipgre_tunnel_validate,
+	.newlink	= ipgre_newlink,
+	.changelink	= ipgre_changelink,
+	.dellink	= ip_tunnel_dellink,
+	.get_size	= ipgre_get_size,
+	.fill_info	= ipgre_fill_info,
+	.get_link_net	= ip_tunnel_get_link_net,
+};
+
+static struct rtnl_link_ops ipgre_tap_ops __read_mostly = {
+	.kind		= "gretap",
+	.maxtype	= IFLA_GRE_MAX,
+	.policy		= ipgre_policy,
+	.priv_size	= sizeof(struct ip_tunnel),
+	.setup		= ipgre_tap_setup,
+	.validate	= ipgre_tap_validate,
+	.newlink	= ipgre_newlink,
+	.changelink	= ipgre_changelink,
+	.dellink	= ip_tunnel_dellink,
+	.get_size	= ipgre_get_size,
+	.fill_info	= ipgre_fill_info,
+	.get_link_net	= ip_tunnel_get_link_net,
+};
+
+static struct rtnl_link_ops erspan_link_ops __read_mostly = {
+	.kind		= "erspan",
+	.maxtype	= IFLA_GRE_MAX,
+	.policy		= ipgre_policy,
+	.priv_size	= sizeof(struct ip_tunnel),
+	.setup		= erspan_setup,
+	.validate	= erspan_validate,
+	.newlink	= erspan_newlink,
+	.changelink	= erspan_changelink,
+	.dellink	= ip_tunnel_dellink,
+	.get_size	= ipgre_get_size,
+	.fill_info	= erspan_fill_info,
+	.get_link_net	= ip_tunnel_get_link_net,
+};
+
+struct net_device *gretap_fb_dev_create(struct net *net, const char *name,
+					u8 name_assign_type)
+{
+	struct nlattr *tb[IFLA_MAX + 1];
+	struct net_device *dev;
+	LIST_HEAD(list_kill);
+	struct ip_tunnel *t;
+	int err;
+
+	memset(&tb, 0, sizeof(tb));
+
+	dev = rtnl_create_link(net, name, name_assign_type,
+			       &ipgre_tap_ops, tb, NULL);
+	if (IS_ERR(dev))
+		return dev;
+
+	/* Configure flow based GRE device. */
+	t = netdev_priv(dev);
+	t->collect_md = true;
+
+	err = ipgre_newlink(net, dev, tb, NULL, NULL);
+	if (err < 0) {
+		free_netdev(dev);
+		return ERR_PTR(err);
+	}
+
+	/* openvswitch users expect packet sizes to be unrestricted,
+	 * so set the largest MTU we can.
+	 */
+	err = __ip_tunnel_change_mtu(dev, IP_MAX_MTU, false);
+	if (err)
+		goto out;
+
+	err = rtnl_configure_link(dev, NULL);
+	if (err < 0)
+		goto out;
+
+	return dev;
+out:
+	ip_tunnel_dellink(dev, &list_kill);
+	unregister_netdevice_many(&list_kill);
+	return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(gretap_fb_dev_create);
+
+static int __net_init ipgre_tap_init_net(struct net *net)
+{
+	return ip_tunnel_init_net(net, gre_tap_net_id, &ipgre_tap_ops, "gretap0");
+}
+
+static void __net_exit ipgre_tap_exit_batch_net(struct list_head *list_net)
+{
+	ip_tunnel_delete_nets(list_net, gre_tap_net_id, &ipgre_tap_ops);
+}
+
+static struct pernet_operations ipgre_tap_net_ops = {
+	.init = ipgre_tap_init_net,
+	.exit_batch = ipgre_tap_exit_batch_net,
+	.id   = &gre_tap_net_id,
+	.size = sizeof(struct ip_tunnel_net),
+};
+
+static int __net_init erspan_init_net(struct net *net)
+{
+	return ip_tunnel_init_net(net, erspan_net_id,
+				  &erspan_link_ops, "erspan0");
+}
+
+static void __net_exit erspan_exit_batch_net(struct list_head *net_list)
+{
+	ip_tunnel_delete_nets(net_list, erspan_net_id, &erspan_link_ops);
+}
+
+static struct pernet_operations erspan_net_ops = {
+	.init = erspan_init_net,
+	.exit_batch = erspan_exit_batch_net,
+	.id   = &erspan_net_id,
+	.size = sizeof(struct ip_tunnel_net),
+};
+
+static int __init ipgre_init(void)
+{
+	int err;
+
+	pr_info("GRE over IPv4 tunneling driver\n");
+
+	err = register_pernet_device(&ipgre_net_ops);
+	if (err < 0)
+		return err;
+
+	err = register_pernet_device(&ipgre_tap_net_ops);
+	if (err < 0)
+		goto pnet_tap_failed;
+
+	err = register_pernet_device(&erspan_net_ops);
+	if (err < 0)
+		goto pnet_erspan_failed;
+
+	err = gre_add_protocol(&ipgre_protocol, GREPROTO_CISCO);
+	if (err < 0) {
+		pr_info("%s: can't add protocol\n", __func__);
+		goto add_proto_failed;
+	}
+
+	err = rtnl_link_register(&ipgre_link_ops);
+	if (err < 0)
+		goto rtnl_link_failed;
+
+	err = rtnl_link_register(&ipgre_tap_ops);
+	if (err < 0)
+		goto tap_ops_failed;
+
+	err = rtnl_link_register(&erspan_link_ops);
+	if (err < 0)
+		goto erspan_link_failed;
+
+	return 0;
+
+erspan_link_failed:
+	rtnl_link_unregister(&ipgre_tap_ops);
+tap_ops_failed:
+	rtnl_link_unregister(&ipgre_link_ops);
+rtnl_link_failed:
+	gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO);
+add_proto_failed:
+	unregister_pernet_device(&erspan_net_ops);
+pnet_erspan_failed:
+	unregister_pernet_device(&ipgre_tap_net_ops);
+pnet_tap_failed:
+	unregister_pernet_device(&ipgre_net_ops);
+	return err;
+}
+
+static void __exit ipgre_fini(void)
+{
+	rtnl_link_unregister(&ipgre_tap_ops);
+	rtnl_link_unregister(&ipgre_link_ops);
+	rtnl_link_unregister(&erspan_link_ops);
+	gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO);
+	unregister_pernet_device(&ipgre_tap_net_ops);
+	unregister_pernet_device(&ipgre_net_ops);
+	unregister_pernet_device(&erspan_net_ops);
+}
+
+module_init(ipgre_init);
+module_exit(ipgre_fini);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_RTNL_LINK("gre");
+MODULE_ALIAS_RTNL_LINK("gretap");
+MODULE_ALIAS_RTNL_LINK("erspan");
+MODULE_ALIAS_NETDEV("gre0");
+MODULE_ALIAS_NETDEV("gretap0");
+MODULE_ALIAS_NETDEV("erspan0");