Adding upstream version 6.1.76.upstream/6.1.76

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

1 files changed, 1335 insertions, 0 deletions

diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c
new file mode 100644
index 000000000..cb71463bb
--- /dev/null
+++ b/net/ipv6/ip6_vti.c
@@ -0,0 +1,1335 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *	IPv6 virtual tunneling interface
+ *
+ *	Copyright (C) 2013 secunet Security Networks AG
+ *
+ *	Author:
+ *	Steffen Klassert <steffen.klassert@secunet.com>
+ *
+ *	Based on:
+ *	net/ipv6/ip6_tunnel.c
+ */
+
+#include <linux/module.h>
+#include <linux/capability.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/sockios.h>
+#include <linux/icmp.h>
+#include <linux/if.h>
+#include <linux/in.h>
+#include <linux/ip.h>
+#include <linux/net.h>
+#include <linux/in6.h>
+#include <linux/netdevice.h>
+#include <linux/if_arp.h>
+#include <linux/icmpv6.h>
+#include <linux/init.h>
+#include <linux/route.h>
+#include <linux/rtnetlink.h>
+#include <linux/netfilter_ipv6.h>
+#include <linux/slab.h>
+#include <linux/hash.h>
+
+#include <linux/uaccess.h>
+#include <linux/atomic.h>
+
+#include <net/icmp.h>
+#include <net/ip.h>
+#include <net/ip_tunnels.h>
+#include <net/ipv6.h>
+#include <net/ip6_route.h>
+#include <net/addrconf.h>
+#include <net/ip6_tunnel.h>
+#include <net/xfrm.h>
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
+#include <linux/etherdevice.h>
+
+#define IP6_VTI_HASH_SIZE_SHIFT  5
+#define IP6_VTI_HASH_SIZE (1 << IP6_VTI_HASH_SIZE_SHIFT)
+
+static u32 HASH(const struct in6_addr *addr1, const struct in6_addr *addr2)
+{
+	u32 hash = ipv6_addr_hash(addr1) ^ ipv6_addr_hash(addr2);
+
+	return hash_32(hash, IP6_VTI_HASH_SIZE_SHIFT);
+}
+
+static int vti6_dev_init(struct net_device *dev);
+static void vti6_dev_setup(struct net_device *dev);
+static struct rtnl_link_ops vti6_link_ops __read_mostly;
+
+static unsigned int vti6_net_id __read_mostly;
+struct vti6_net {
+	/* the vti6 tunnel fallback device */
+	struct net_device *fb_tnl_dev;
+	/* lists for storing tunnels in use */
+	struct ip6_tnl __rcu *tnls_r_l[IP6_VTI_HASH_SIZE];
+	struct ip6_tnl __rcu *tnls_wc[1];
+	struct ip6_tnl __rcu **tnls[2];
+};
+
+#define for_each_vti6_tunnel_rcu(start) \
+	for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))
+
+/**
+ * vti6_tnl_lookup - fetch tunnel matching the end-point addresses
+ *   @net: network namespace
+ *   @remote: the address of the tunnel exit-point
+ *   @local: the address of the tunnel entry-point
+ *
+ * Return:
+ *   tunnel matching given end-points if found,
+ *   else fallback tunnel if its device is up,
+ *   else %NULL
+ **/
+static struct ip6_tnl *
+vti6_tnl_lookup(struct net *net, const struct in6_addr *remote,
+		const struct in6_addr *local)
+{
+	unsigned int hash = HASH(remote, local);
+	struct ip6_tnl *t;
+	struct vti6_net *ip6n = net_generic(net, vti6_net_id);
+	struct in6_addr any;
+
+	for_each_vti6_tunnel_rcu(ip6n->tnls_r_l[hash]) {
+		if (ipv6_addr_equal(local, &t->parms.laddr) &&
+		    ipv6_addr_equal(remote, &t->parms.raddr) &&
+		    (t->dev->flags & IFF_UP))
+			return t;
+	}
+
+	memset(&any, 0, sizeof(any));
+	hash = HASH(&any, local);
+	for_each_vti6_tunnel_rcu(ip6n->tnls_r_l[hash]) {
+		if (ipv6_addr_equal(local, &t->parms.laddr) &&
+		    (t->dev->flags & IFF_UP))
+			return t;
+	}
+
+	hash = HASH(remote, &any);
+	for_each_vti6_tunnel_rcu(ip6n->tnls_r_l[hash]) {
+		if (ipv6_addr_equal(remote, &t->parms.raddr) &&
+		    (t->dev->flags & IFF_UP))
+			return t;
+	}
+
+	t = rcu_dereference(ip6n->tnls_wc[0]);
+	if (t && (t->dev->flags & IFF_UP))
+		return t;
+
+	return NULL;
+}
+
+/**
+ * vti6_tnl_bucket - get head of list matching given tunnel parameters
+ *   @ip6n: the private data for ip6_vti in the netns
+ *   @p: parameters containing tunnel end-points
+ *
+ * Description:
+ *   vti6_tnl_bucket() returns the head of the list matching the
+ *   &struct in6_addr entries laddr and raddr in @p.
+ *
+ * Return: head of IPv6 tunnel list
+ **/
+static struct ip6_tnl __rcu **
+vti6_tnl_bucket(struct vti6_net *ip6n, const struct __ip6_tnl_parm *p)
+{
+	const struct in6_addr *remote = &p->raddr;
+	const struct in6_addr *local = &p->laddr;
+	unsigned int h = 0;
+	int prio = 0;
+
+	if (!ipv6_addr_any(remote) || !ipv6_addr_any(local)) {
+		prio = 1;
+		h = HASH(remote, local);
+	}
+	return &ip6n->tnls[prio][h];
+}
+
+static void
+vti6_tnl_link(struct vti6_net *ip6n, struct ip6_tnl *t)
+{
+	struct ip6_tnl __rcu **tp = vti6_tnl_bucket(ip6n, &t->parms);
+
+	rcu_assign_pointer(t->next, rtnl_dereference(*tp));
+	rcu_assign_pointer(*tp, t);
+}
+
+static void
+vti6_tnl_unlink(struct vti6_net *ip6n, struct ip6_tnl *t)
+{
+	struct ip6_tnl __rcu **tp;
+	struct ip6_tnl *iter;
+
+	for (tp = vti6_tnl_bucket(ip6n, &t->parms);
+	     (iter = rtnl_dereference(*tp)) != NULL;
+	     tp = &iter->next) {
+		if (t == iter) {
+			rcu_assign_pointer(*tp, t->next);
+			break;
+		}
+	}
+}
+
+static void vti6_dev_free(struct net_device *dev)
+{
+	free_percpu(dev->tstats);
+}
+
+static int vti6_tnl_create2(struct net_device *dev)
+{
+	struct ip6_tnl *t = netdev_priv(dev);
+	struct net *net = dev_net(dev);
+	struct vti6_net *ip6n = net_generic(net, vti6_net_id);
+	int err;
+
+	dev->rtnl_link_ops = &vti6_link_ops;
+	err = register_netdevice(dev);
+	if (err < 0)
+		goto out;
+
+	strcpy(t->parms.name, dev->name);
+
+	vti6_tnl_link(ip6n, t);
+
+	return 0;
+
+out:
+	return err;
+}
+
+static struct ip6_tnl *vti6_tnl_create(struct net *net, struct __ip6_tnl_parm *p)
+{
+	struct net_device *dev;
+	struct ip6_tnl *t;
+	char name[IFNAMSIZ];
+	int err;
+
+	if (p->name[0]) {
+		if (!dev_valid_name(p->name))
+			goto failed;
+		strscpy(name, p->name, IFNAMSIZ);
+	} else {
+		sprintf(name, "ip6_vti%%d");
+	}
+
+	dev = alloc_netdev(sizeof(*t), name, NET_NAME_UNKNOWN, vti6_dev_setup);
+	if (!dev)
+		goto failed;
+
+	dev_net_set(dev, net);
+
+	t = netdev_priv(dev);
+	t->parms = *p;
+	t->net = dev_net(dev);
+
+	err = vti6_tnl_create2(dev);
+	if (err < 0)
+		goto failed_free;
+
+	return t;
+
+failed_free:
+	free_netdev(dev);
+failed:
+	return NULL;
+}
+
+/**
+ * vti6_locate - find or create tunnel matching given parameters
+ *   @net: network namespace
+ *   @p: tunnel parameters
+ *   @create: != 0 if allowed to create new tunnel if no match found
+ *
+ * Description:
+ *   vti6_locate() first tries to locate an existing tunnel
+ *   based on @parms. If this is unsuccessful, but @create is set a new
+ *   tunnel device is created and registered for use.
+ *
+ * Return:
+ *   matching tunnel or NULL
+ **/
+static struct ip6_tnl *vti6_locate(struct net *net, struct __ip6_tnl_parm *p,
+				   int create)
+{
+	const struct in6_addr *remote = &p->raddr;
+	const struct in6_addr *local = &p->laddr;
+	struct ip6_tnl __rcu **tp;
+	struct ip6_tnl *t;
+	struct vti6_net *ip6n = net_generic(net, vti6_net_id);
+
+	for (tp = vti6_tnl_bucket(ip6n, p);
+	     (t = rtnl_dereference(*tp)) != NULL;
+	     tp = &t->next) {
+		if (ipv6_addr_equal(local, &t->parms.laddr) &&
+		    ipv6_addr_equal(remote, &t->parms.raddr)) {
+			if (create)
+				return NULL;
+
+			return t;
+		}
+	}
+	if (!create)
+		return NULL;
+	return vti6_tnl_create(net, p);
+}
+
+/**
+ * vti6_dev_uninit - tunnel device uninitializer
+ *   @dev: the device to be destroyed
+ *
+ * Description:
+ *   vti6_dev_uninit() removes tunnel from its list
+ **/
+static void vti6_dev_uninit(struct net_device *dev)
+{
+	struct ip6_tnl *t = netdev_priv(dev);
+	struct vti6_net *ip6n = net_generic(t->net, vti6_net_id);
+
+	if (dev == ip6n->fb_tnl_dev)
+		RCU_INIT_POINTER(ip6n->tnls_wc[0], NULL);
+	else
+		vti6_tnl_unlink(ip6n, t);
+	netdev_put(dev, &t->dev_tracker);
+}
+
+static int vti6_input_proto(struct sk_buff *skb, int nexthdr, __be32 spi,
+			    int encap_type)
+{
+	struct ip6_tnl *t;
+	const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
+
+	rcu_read_lock();
+	t = vti6_tnl_lookup(dev_net(skb->dev), &ipv6h->saddr, &ipv6h->daddr);
+	if (t) {
+		if (t->parms.proto != IPPROTO_IPV6 && t->parms.proto != 0) {
+			rcu_read_unlock();
+			goto discard;
+		}
+
+		if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
+			rcu_read_unlock();
+			goto discard;
+		}
+
+		ipv6h = ipv6_hdr(skb);
+		if (!ip6_tnl_rcv_ctl(t, &ipv6h->daddr, &ipv6h->saddr)) {
+			t->dev->stats.rx_dropped++;
+			rcu_read_unlock();
+			goto discard;
+		}
+
+		rcu_read_unlock();
+
+		XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = t;
+		XFRM_SPI_SKB_CB(skb)->family = AF_INET6;
+		XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
+		return xfrm_input(skb, nexthdr, spi, encap_type);
+	}
+	rcu_read_unlock();
+	return -EINVAL;
+discard:
+	kfree_skb(skb);
+	return 0;
+}
+
+static int vti6_rcv(struct sk_buff *skb)
+{
+	int nexthdr = skb_network_header(skb)[IP6CB(skb)->nhoff];
+
+	return vti6_input_proto(skb, nexthdr, 0, 0);
+}
+
+static int vti6_rcv_cb(struct sk_buff *skb, int err)
+{
+	unsigned short family;
+	struct net_device *dev;
+	struct xfrm_state *x;
+	const struct xfrm_mode *inner_mode;
+	struct ip6_tnl *t = XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6;
+	u32 orig_mark = skb->mark;
+	int ret;
+
+	if (!t)
+		return 1;
+
+	dev = t->dev;
+
+	if (err) {
+		dev->stats.rx_errors++;
+		dev->stats.rx_dropped++;
+
+		return 0;
+	}
+
+	x = xfrm_input_state(skb);
+
+	inner_mode = &x->inner_mode;
+
+	if (x->sel.family == AF_UNSPEC) {
+		inner_mode = xfrm_ip2inner_mode(x, XFRM_MODE_SKB_CB(skb)->protocol);
+		if (inner_mode == NULL) {
+			XFRM_INC_STATS(dev_net(skb->dev),
+				       LINUX_MIB_XFRMINSTATEMODEERROR);
+			return -EINVAL;
+		}
+	}
+
+	family = inner_mode->family;
+
+	skb->mark = be32_to_cpu(t->parms.i_key);
+	ret = xfrm_policy_check(NULL, XFRM_POLICY_IN, skb, family);
+	skb->mark = orig_mark;
+
+	if (!ret)
+		return -EPERM;
+
+	skb_scrub_packet(skb, !net_eq(t->net, dev_net(skb->dev)));
+	skb->dev = dev;
+	dev_sw_netstats_rx_add(dev, skb->len);
+
+	return 0;
+}
+
+/**
+ * vti6_addr_conflict - compare packet addresses to tunnel's own
+ *   @t: the outgoing tunnel device
+ *   @hdr: IPv6 header from the incoming packet
+ *
+ * Description:
+ *   Avoid trivial tunneling loop by checking that tunnel exit-point
+ *   doesn't match source of incoming packet.
+ *
+ * Return:
+ *   1 if conflict,
+ *   0 else
+ **/
+static inline bool
+vti6_addr_conflict(const struct ip6_tnl *t, const struct ipv6hdr *hdr)
+{
+	return ipv6_addr_equal(&t->parms.raddr, &hdr->saddr);
+}
+
+static bool vti6_state_check(const struct xfrm_state *x,
+			     const struct in6_addr *dst,
+			     const struct in6_addr *src)
+{
+	xfrm_address_t *daddr = (xfrm_address_t *)dst;
+	xfrm_address_t *saddr = (xfrm_address_t *)src;
+
+	/* if there is no transform then this tunnel is not functional.
+	 * Or if the xfrm is not mode tunnel.
+	 */
+	if (!x || x->props.mode != XFRM_MODE_TUNNEL ||
+	    x->props.family != AF_INET6)
+		return false;
+
+	if (ipv6_addr_any(dst))
+		return xfrm_addr_equal(saddr, &x->props.saddr, AF_INET6);
+
+	if (!xfrm_state_addr_check(x, daddr, saddr, AF_INET6))
+		return false;
+
+	return true;
+}
+
+/**
+ * vti6_xmit - send a packet
+ *   @skb: the outgoing socket buffer
+ *   @dev: the outgoing tunnel device
+ *   @fl: the flow informations for the xfrm_lookup
+ **/
+static int
+vti6_xmit(struct sk_buff *skb, struct net_device *dev, struct flowi *fl)
+{
+	struct ip6_tnl *t = netdev_priv(dev);
+	struct net_device_stats *stats = &t->dev->stats;
+	struct dst_entry *dst = skb_dst(skb);
+	struct net_device *tdev;
+	struct xfrm_state *x;
+	int pkt_len = skb->len;
+	int err = -1;
+	int mtu;
+
+	if (!dst) {
+		switch (skb->protocol) {
+		case htons(ETH_P_IP): {
+			struct rtable *rt;
+
+			fl->u.ip4.flowi4_oif = dev->ifindex;
+			fl->u.ip4.flowi4_flags |= FLOWI_FLAG_ANYSRC;
+			rt = __ip_route_output_key(dev_net(dev), &fl->u.ip4);
+			if (IS_ERR(rt))
+				goto tx_err_link_failure;
+			dst = &rt->dst;
+			skb_dst_set(skb, dst);
+			break;
+		}
+		case htons(ETH_P_IPV6):
+			fl->u.ip6.flowi6_oif = dev->ifindex;
+			fl->u.ip6.flowi6_flags |= FLOWI_FLAG_ANYSRC;
+			dst = ip6_route_output(dev_net(dev), NULL, &fl->u.ip6);
+			if (dst->error) {
+				dst_release(dst);
+				dst = NULL;
+				goto tx_err_link_failure;
+			}
+			skb_dst_set(skb, dst);
+			break;
+		default:
+			goto tx_err_link_failure;
+		}
+	}
+
+	dst_hold(dst);
+	dst = xfrm_lookup_route(t->net, dst, fl, NULL, 0);
+	if (IS_ERR(dst)) {
+		err = PTR_ERR(dst);
+		dst = NULL;
+		goto tx_err_link_failure;
+	}
+
+	if (dst->flags & DST_XFRM_QUEUE)
+		goto xmit;
+
+	x = dst->xfrm;
+	if (!vti6_state_check(x, &t->parms.raddr, &t->parms.laddr))
+		goto tx_err_link_failure;
+
+	if (!ip6_tnl_xmit_ctl(t, (const struct in6_addr *)&x->props.saddr,
+			      (const struct in6_addr *)&x->id.daddr))
+		goto tx_err_link_failure;
+
+	tdev = dst->dev;
+
+	if (tdev == dev) {
+		stats->collisions++;
+		net_warn_ratelimited("%s: Local routing loop detected!\n",
+				     t->parms.name);
+		goto tx_err_dst_release;
+	}
+
+	mtu = dst_mtu(dst);
+	if (skb->len > mtu) {
+		skb_dst_update_pmtu_no_confirm(skb, mtu);
+
+		if (skb->protocol == htons(ETH_P_IPV6)) {
+			if (mtu < IPV6_MIN_MTU)
+				mtu = IPV6_MIN_MTU;
+
+			icmpv6_ndo_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
+		} else {
+			if (!(ip_hdr(skb)->frag_off & htons(IP_DF)))
+				goto xmit;
+			icmp_ndo_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
+				      htonl(mtu));
+		}
+
+		err = -EMSGSIZE;
+		goto tx_err_dst_release;
+	}
+
+xmit:
+	skb_scrub_packet(skb, !net_eq(t->net, dev_net(dev)));
+	skb_dst_set(skb, dst);
+	skb->dev = skb_dst(skb)->dev;
+
+	err = dst_output(t->net, skb->sk, skb);
+	if (net_xmit_eval(err) == 0)
+		err = pkt_len;
+	iptunnel_xmit_stats(dev, err);
+
+	return 0;
+tx_err_link_failure:
+	stats->tx_carrier_errors++;
+	dst_link_failure(skb);
+tx_err_dst_release:
+	dst_release(dst);
+	return err;
+}
+
+static netdev_tx_t
+vti6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct ip6_tnl *t = netdev_priv(dev);
+	struct net_device_stats *stats = &t->dev->stats;
+	struct flowi fl;
+	int ret;
+
+	if (!pskb_inet_may_pull(skb))
+		goto tx_err;
+
+	memset(&fl, 0, sizeof(fl));
+
+	switch (skb->protocol) {
+	case htons(ETH_P_IPV6):
+		if ((t->parms.proto != IPPROTO_IPV6 && t->parms.proto != 0) ||
+		    vti6_addr_conflict(t, ipv6_hdr(skb)))
+			goto tx_err;
+
+		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
+		xfrm_decode_session(skb, &fl, AF_INET6);
+		break;
+	case htons(ETH_P_IP):
+		memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
+		xfrm_decode_session(skb, &fl, AF_INET);
+		break;
+	default:
+		goto tx_err;
+	}
+
+	/* override mark with tunnel output key */
+	fl.flowi_mark = be32_to_cpu(t->parms.o_key);
+
+	ret = vti6_xmit(skb, dev, &fl);
+	if (ret < 0)
+		goto tx_err;
+
+	return NETDEV_TX_OK;
+
+tx_err:
+	stats->tx_errors++;
+	stats->tx_dropped++;
+	kfree_skb(skb);
+	return NETDEV_TX_OK;
+}
+
+static int vti6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
+		    u8 type, u8 code, int offset, __be32 info)
+{
+	__be32 spi;
+	__u32 mark;
+	struct xfrm_state *x;
+	struct ip6_tnl *t;
+	struct ip_esp_hdr *esph;
+	struct ip_auth_hdr *ah;
+	struct ip_comp_hdr *ipch;
+	struct net *net = dev_net(skb->dev);
+	const struct ipv6hdr *iph = (const struct ipv6hdr *)skb->data;
+	int protocol = iph->nexthdr;
+
+	t = vti6_tnl_lookup(dev_net(skb->dev), &iph->daddr, &iph->saddr);
+	if (!t)
+		return -1;
+
+	mark = be32_to_cpu(t->parms.o_key);
+
+	switch (protocol) {
+	case IPPROTO_ESP:
+		esph = (struct ip_esp_hdr *)(skb->data + offset);
+		spi = esph->spi;
+		break;
+	case IPPROTO_AH:
+		ah = (struct ip_auth_hdr *)(skb->data + offset);
+		spi = ah->spi;
+		break;
+	case IPPROTO_COMP:
+		ipch = (struct ip_comp_hdr *)(skb->data + offset);
+		spi = htonl(ntohs(ipch->cpi));
+		break;
+	default:
+		return 0;
+	}
+
+	if (type != ICMPV6_PKT_TOOBIG &&
+	    type != NDISC_REDIRECT)
+		return 0;
+
+	x = xfrm_state_lookup(net, mark, (const xfrm_address_t *)&iph->daddr,
+			      spi, protocol, AF_INET6);
+	if (!x)
+		return 0;
+
+	if (type == NDISC_REDIRECT)
+		ip6_redirect(skb, net, skb->dev->ifindex, 0,
+			     sock_net_uid(net, NULL));
+	else
+		ip6_update_pmtu(skb, net, info, 0, 0, sock_net_uid(net, NULL));
+	xfrm_state_put(x);
+
+	return 0;
+}
+
+static void vti6_link_config(struct ip6_tnl *t, bool keep_mtu)
+{
+	struct net_device *dev = t->dev;
+	struct __ip6_tnl_parm *p = &t->parms;
+	struct net_device *tdev = NULL;
+	int mtu;
+
+	__dev_addr_set(dev, &p->laddr, sizeof(struct in6_addr));
+	memcpy(dev->broadcast, &p->raddr, sizeof(struct in6_addr));
+
+	p->flags &= ~(IP6_TNL_F_CAP_XMIT | IP6_TNL_F_CAP_RCV |
+		      IP6_TNL_F_CAP_PER_PACKET);
+	p->flags |= ip6_tnl_get_cap(t, &p->laddr, &p->raddr);
+
+	if (p->flags & IP6_TNL_F_CAP_XMIT && p->flags & IP6_TNL_F_CAP_RCV)
+		dev->flags |= IFF_POINTOPOINT;
+	else
+		dev->flags &= ~IFF_POINTOPOINT;
+
+	if (keep_mtu && dev->mtu) {
+		dev->mtu = clamp(dev->mtu, dev->min_mtu, dev->max_mtu);
+		return;
+	}
+
+	if (p->flags & IP6_TNL_F_CAP_XMIT) {
+		int strict = (ipv6_addr_type(&p->raddr) &
+			      (IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL));
+		struct rt6_info *rt = rt6_lookup(t->net,
+						 &p->raddr, &p->laddr,
+						 p->link, NULL, strict);
+
+		if (rt)
+			tdev = rt->dst.dev;
+		ip6_rt_put(rt);
+	}
+
+	if (!tdev && p->link)
+		tdev = __dev_get_by_index(t->net, p->link);
+
+	if (tdev)
+		mtu = tdev->mtu - sizeof(struct ipv6hdr);
+	else
+		mtu = ETH_DATA_LEN - LL_MAX_HEADER - sizeof(struct ipv6hdr);
+
+	dev->mtu = max_t(int, mtu, IPV4_MIN_MTU);
+}
+
+/**
+ * vti6_tnl_change - update the tunnel parameters
+ *   @t: tunnel to be changed
+ *   @p: tunnel configuration parameters
+ *   @keep_mtu: MTU was set from userspace, don't re-compute it
+ *
+ * Description:
+ *   vti6_tnl_change() updates the tunnel parameters
+ **/
+static int
+vti6_tnl_change(struct ip6_tnl *t, const struct __ip6_tnl_parm *p,
+		bool keep_mtu)
+{
+	t->parms.laddr = p->laddr;
+	t->parms.raddr = p->raddr;
+	t->parms.link = p->link;
+	t->parms.i_key = p->i_key;
+	t->parms.o_key = p->o_key;
+	t->parms.proto = p->proto;
+	t->parms.fwmark = p->fwmark;
+	dst_cache_reset(&t->dst_cache);
+	vti6_link_config(t, keep_mtu);
+	return 0;
+}
+
+static int vti6_update(struct ip6_tnl *t, struct __ip6_tnl_parm *p,
+		       bool keep_mtu)
+{
+	struct net *net = dev_net(t->dev);
+	struct vti6_net *ip6n = net_generic(net, vti6_net_id);
+	int err;
+
+	vti6_tnl_unlink(ip6n, t);
+	synchronize_net();
+	err = vti6_tnl_change(t, p, keep_mtu);
+	vti6_tnl_link(ip6n, t);
+	netdev_state_change(t->dev);
+	return err;
+}
+
+static void
+vti6_parm_from_user(struct __ip6_tnl_parm *p, const struct ip6_tnl_parm2 *u)
+{
+	p->laddr = u->laddr;
+	p->raddr = u->raddr;
+	p->link = u->link;
+	p->i_key = u->i_key;
+	p->o_key = u->o_key;
+	p->proto = u->proto;
+
+	memcpy(p->name, u->name, sizeof(u->name));
+}
+
+static void
+vti6_parm_to_user(struct ip6_tnl_parm2 *u, const struct __ip6_tnl_parm *p)
+{
+	u->laddr = p->laddr;
+	u->raddr = p->raddr;
+	u->link = p->link;
+	u->i_key = p->i_key;
+	u->o_key = p->o_key;
+	if (u->i_key)
+		u->i_flags |= GRE_KEY;
+	if (u->o_key)
+		u->o_flags |= GRE_KEY;
+	u->proto = p->proto;
+
+	memcpy(u->name, p->name, sizeof(u->name));
+}
+
+/**
+ * vti6_siocdevprivate - configure vti6 tunnels from userspace
+ *   @dev: virtual device associated with tunnel
+ *   @ifr: unused
+ *   @data: parameters passed from userspace
+ *   @cmd: command to be performed
+ *
+ * Description:
+ *   vti6_siocdevprivate() is used for managing vti6 tunnels
+ *   from userspace.
+ *
+ *   The possible commands are the following:
+ *     %SIOCGETTUNNEL: get tunnel parameters for device
+ *     %SIOCADDTUNNEL: add tunnel matching given tunnel parameters
+ *     %SIOCCHGTUNNEL: change tunnel parameters to those given
+ *     %SIOCDELTUNNEL: delete tunnel
+ *
+ *   The fallback device "ip6_vti0", created during module
+ *   initialization, can be used for creating other tunnel devices.
+ *
+ * Return:
+ *   0 on success,
+ *   %-EFAULT if unable to copy data to or from userspace,
+ *   %-EPERM if current process hasn't %CAP_NET_ADMIN set
+ *   %-EINVAL if passed tunnel parameters are invalid,
+ *   %-EEXIST if changing a tunnel's parameters would cause a conflict
+ *   %-ENODEV if attempting to change or delete a nonexisting device
+ **/
+static int
+vti6_siocdevprivate(struct net_device *dev, struct ifreq *ifr, void __user *data, int cmd)
+{
+	int err = 0;
+	struct ip6_tnl_parm2 p;
+	struct __ip6_tnl_parm p1;
+	struct ip6_tnl *t = NULL;
+	struct net *net = dev_net(dev);
+	struct vti6_net *ip6n = net_generic(net, vti6_net_id);
+
+	memset(&p1, 0, sizeof(p1));
+
+	switch (cmd) {
+	case SIOCGETTUNNEL:
+		if (dev == ip6n->fb_tnl_dev) {
+			if (copy_from_user(&p, data, sizeof(p))) {
+				err = -EFAULT;
+				break;
+			}
+			vti6_parm_from_user(&p1, &p);
+			t = vti6_locate(net, &p1, 0);
+		} else {
+			memset(&p, 0, sizeof(p));
+		}
+		if (!t)
+			t = netdev_priv(dev);
+		vti6_parm_to_user(&p, &t->parms);
+		if (copy_to_user(data, &p, sizeof(p)))
+			err = -EFAULT;
+		break;
+	case SIOCADDTUNNEL:
+	case SIOCCHGTUNNEL:
+		err = -EPERM;
+		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
+			break;
+		err = -EFAULT;
+		if (copy_from_user(&p, data, sizeof(p)))
+			break;
+		err = -EINVAL;
+		if (p.proto != IPPROTO_IPV6  && p.proto != 0)
+			break;
+		vti6_parm_from_user(&p1, &p);
+		t = vti6_locate(net, &p1, cmd == SIOCADDTUNNEL);
+		if (dev != ip6n->fb_tnl_dev && cmd == SIOCCHGTUNNEL) {
+			if (t) {
+				if (t->dev != dev) {
+					err = -EEXIST;
+					break;
+				}
+			} else
+				t = netdev_priv(dev);
+
+			err = vti6_update(t, &p1, false);
+		}
+		if (t) {
+			err = 0;
+			vti6_parm_to_user(&p, &t->parms);
+			if (copy_to_user(data, &p, sizeof(p)))
+				err = -EFAULT;
+
+		} else
+			err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
+		break;
+	case SIOCDELTUNNEL:
+		err = -EPERM;
+		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
+			break;
+
+		if (dev == ip6n->fb_tnl_dev) {
+			err = -EFAULT;
+			if (copy_from_user(&p, data, sizeof(p)))
+				break;
+			err = -ENOENT;
+			vti6_parm_from_user(&p1, &p);
+			t = vti6_locate(net, &p1, 0);
+			if (!t)
+				break;
+			err = -EPERM;
+			if (t->dev == ip6n->fb_tnl_dev)
+				break;
+			dev = t->dev;
+		}
+		err = 0;
+		unregister_netdevice(dev);
+		break;
+	default:
+		err = -EINVAL;
+	}
+	return err;
+}
+
+static const struct net_device_ops vti6_netdev_ops = {
+	.ndo_init	= vti6_dev_init,
+	.ndo_uninit	= vti6_dev_uninit,
+	.ndo_start_xmit = vti6_tnl_xmit,
+	.ndo_siocdevprivate = vti6_siocdevprivate,
+	.ndo_get_stats64 = dev_get_tstats64,
+	.ndo_get_iflink = ip6_tnl_get_iflink,
+};
+
+/**
+ * vti6_dev_setup - setup virtual tunnel device
+ *   @dev: virtual device associated with tunnel
+ *
+ * Description:
+ *   Initialize function pointers and device parameters
+ **/
+static void vti6_dev_setup(struct net_device *dev)
+{
+	dev->netdev_ops = &vti6_netdev_ops;
+	dev->header_ops = &ip_tunnel_header_ops;
+	dev->needs_free_netdev = true;
+	dev->priv_destructor = vti6_dev_free;
+
+	dev->type = ARPHRD_TUNNEL6;
+	dev->min_mtu = IPV4_MIN_MTU;
+	dev->max_mtu = IP_MAX_MTU - sizeof(struct ipv6hdr);
+	dev->flags |= IFF_NOARP;
+	dev->addr_len = sizeof(struct in6_addr);
+	netif_keep_dst(dev);
+	/* This perm addr will be used as interface identifier by IPv6 */
+	dev->addr_assign_type = NET_ADDR_RANDOM;
+	eth_random_addr(dev->perm_addr);
+}
+
+/**
+ * vti6_dev_init_gen - general initializer for all tunnel devices
+ *   @dev: virtual device associated with tunnel
+ **/
+static inline int vti6_dev_init_gen(struct net_device *dev)
+{
+	struct ip6_tnl *t = netdev_priv(dev);
+
+	t->dev = dev;
+	t->net = dev_net(dev);
+	dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
+	if (!dev->tstats)
+		return -ENOMEM;
+	netdev_hold(dev, &t->dev_tracker, GFP_KERNEL);
+	return 0;
+}
+
+/**
+ * vti6_dev_init - initializer for all non fallback tunnel devices
+ *   @dev: virtual device associated with tunnel
+ **/
+static int vti6_dev_init(struct net_device *dev)
+{
+	struct ip6_tnl *t = netdev_priv(dev);
+	int err = vti6_dev_init_gen(dev);
+
+	if (err)
+		return err;
+	vti6_link_config(t, true);
+	return 0;
+}
+
+/**
+ * vti6_fb_tnl_dev_init - initializer for fallback tunnel device
+ *   @dev: fallback device
+ *
+ * Return: 0
+ **/
+static int __net_init vti6_fb_tnl_dev_init(struct net_device *dev)
+{
+	struct ip6_tnl *t = netdev_priv(dev);
+	struct net *net = dev_net(dev);
+	struct vti6_net *ip6n = net_generic(net, vti6_net_id);
+
+	t->parms.proto = IPPROTO_IPV6;
+
+	rcu_assign_pointer(ip6n->tnls_wc[0], t);
+	return 0;
+}
+
+static int vti6_validate(struct nlattr *tb[], struct nlattr *data[],
+			 struct netlink_ext_ack *extack)
+{
+	return 0;
+}
+
+static void vti6_netlink_parms(struct nlattr *data[],
+			       struct __ip6_tnl_parm *parms)
+{
+	memset(parms, 0, sizeof(*parms));
+
+	if (!data)
+		return;
+
+	if (data[IFLA_VTI_LINK])
+		parms->link = nla_get_u32(data[IFLA_VTI_LINK]);
+
+	if (data[IFLA_VTI_LOCAL])
+		parms->laddr = nla_get_in6_addr(data[IFLA_VTI_LOCAL]);
+
+	if (data[IFLA_VTI_REMOTE])
+		parms->raddr = nla_get_in6_addr(data[IFLA_VTI_REMOTE]);
+
+	if (data[IFLA_VTI_IKEY])
+		parms->i_key = nla_get_be32(data[IFLA_VTI_IKEY]);
+
+	if (data[IFLA_VTI_OKEY])
+		parms->o_key = nla_get_be32(data[IFLA_VTI_OKEY]);
+
+	if (data[IFLA_VTI_FWMARK])
+		parms->fwmark = nla_get_u32(data[IFLA_VTI_FWMARK]);
+}
+
+static int vti6_newlink(struct net *src_net, struct net_device *dev,
+			struct nlattr *tb[], struct nlattr *data[],
+			struct netlink_ext_ack *extack)
+{
+	struct net *net = dev_net(dev);
+	struct ip6_tnl *nt;
+
+	nt = netdev_priv(dev);
+	vti6_netlink_parms(data, &nt->parms);
+
+	nt->parms.proto = IPPROTO_IPV6;
+
+	if (vti6_locate(net, &nt->parms, 0))
+		return -EEXIST;
+
+	return vti6_tnl_create2(dev);
+}
+
+static void vti6_dellink(struct net_device *dev, struct list_head *head)
+{
+	struct net *net = dev_net(dev);
+	struct vti6_net *ip6n = net_generic(net, vti6_net_id);
+
+	if (dev != ip6n->fb_tnl_dev)
+		unregister_netdevice_queue(dev, head);
+}
+
+static int vti6_changelink(struct net_device *dev, struct nlattr *tb[],
+			   struct nlattr *data[],
+			   struct netlink_ext_ack *extack)
+{
+	struct ip6_tnl *t;
+	struct __ip6_tnl_parm p;
+	struct net *net = dev_net(dev);
+	struct vti6_net *ip6n = net_generic(net, vti6_net_id);
+
+	if (dev == ip6n->fb_tnl_dev)
+		return -EINVAL;
+
+	vti6_netlink_parms(data, &p);
+
+	t = vti6_locate(net, &p, 0);
+
+	if (t) {
+		if (t->dev != dev)
+			return -EEXIST;
+	} else
+		t = netdev_priv(dev);
+
+	return vti6_update(t, &p, tb && tb[IFLA_MTU]);
+}
+
+static size_t vti6_get_size(const struct net_device *dev)
+{
+	return
+		/* IFLA_VTI_LINK */
+		nla_total_size(4) +
+		/* IFLA_VTI_LOCAL */
+		nla_total_size(sizeof(struct in6_addr)) +
+		/* IFLA_VTI_REMOTE */
+		nla_total_size(sizeof(struct in6_addr)) +
+		/* IFLA_VTI_IKEY */
+		nla_total_size(4) +
+		/* IFLA_VTI_OKEY */
+		nla_total_size(4) +
+		/* IFLA_VTI_FWMARK */
+		nla_total_size(4) +
+		0;
+}
+
+static int vti6_fill_info(struct sk_buff *skb, const struct net_device *dev)
+{
+	struct ip6_tnl *tunnel = netdev_priv(dev);
+	struct __ip6_tnl_parm *parm = &tunnel->parms;
+
+	if (nla_put_u32(skb, IFLA_VTI_LINK, parm->link) ||
+	    nla_put_in6_addr(skb, IFLA_VTI_LOCAL, &parm->laddr) ||
+	    nla_put_in6_addr(skb, IFLA_VTI_REMOTE, &parm->raddr) ||
+	    nla_put_be32(skb, IFLA_VTI_IKEY, parm->i_key) ||
+	    nla_put_be32(skb, IFLA_VTI_OKEY, parm->o_key) ||
+	    nla_put_u32(skb, IFLA_VTI_FWMARK, parm->fwmark))
+		goto nla_put_failure;
+	return 0;
+
+nla_put_failure:
+	return -EMSGSIZE;
+}
+
+static const struct nla_policy vti6_policy[IFLA_VTI_MAX + 1] = {
+	[IFLA_VTI_LINK]		= { .type = NLA_U32 },
+	[IFLA_VTI_LOCAL]	= { .len = sizeof(struct in6_addr) },
+	[IFLA_VTI_REMOTE]	= { .len = sizeof(struct in6_addr) },
+	[IFLA_VTI_IKEY]		= { .type = NLA_U32 },
+	[IFLA_VTI_OKEY]		= { .type = NLA_U32 },
+	[IFLA_VTI_FWMARK]	= { .type = NLA_U32 },
+};
+
+static struct rtnl_link_ops vti6_link_ops __read_mostly = {
+	.kind		= "vti6",
+	.maxtype	= IFLA_VTI_MAX,
+	.policy		= vti6_policy,
+	.priv_size	= sizeof(struct ip6_tnl),
+	.setup		= vti6_dev_setup,
+	.validate	= vti6_validate,
+	.newlink	= vti6_newlink,
+	.dellink	= vti6_dellink,
+	.changelink	= vti6_changelink,
+	.get_size	= vti6_get_size,
+	.fill_info	= vti6_fill_info,
+	.get_link_net	= ip6_tnl_get_link_net,
+};
+
+static void __net_exit vti6_destroy_tunnels(struct vti6_net *ip6n,
+					    struct list_head *list)
+{
+	int h;
+	struct ip6_tnl *t;
+
+	for (h = 0; h < IP6_VTI_HASH_SIZE; h++) {
+		t = rtnl_dereference(ip6n->tnls_r_l[h]);
+		while (t) {
+			unregister_netdevice_queue(t->dev, list);
+			t = rtnl_dereference(t->next);
+		}
+	}
+
+	t = rtnl_dereference(ip6n->tnls_wc[0]);
+	if (t)
+		unregister_netdevice_queue(t->dev, list);
+}
+
+static int __net_init vti6_init_net(struct net *net)
+{
+	struct vti6_net *ip6n = net_generic(net, vti6_net_id);
+	struct ip6_tnl *t = NULL;
+	int err;
+
+	ip6n->tnls[0] = ip6n->tnls_wc;
+	ip6n->tnls[1] = ip6n->tnls_r_l;
+
+	if (!net_has_fallback_tunnels(net))
+		return 0;
+	err = -ENOMEM;
+	ip6n->fb_tnl_dev = alloc_netdev(sizeof(struct ip6_tnl), "ip6_vti0",
+					NET_NAME_UNKNOWN, vti6_dev_setup);
+
+	if (!ip6n->fb_tnl_dev)
+		goto err_alloc_dev;
+	dev_net_set(ip6n->fb_tnl_dev, net);
+	ip6n->fb_tnl_dev->rtnl_link_ops = &vti6_link_ops;
+
+	err = vti6_fb_tnl_dev_init(ip6n->fb_tnl_dev);
+	if (err < 0)
+		goto err_register;
+
+	err = register_netdev(ip6n->fb_tnl_dev);
+	if (err < 0)
+		goto err_register;
+
+	t = netdev_priv(ip6n->fb_tnl_dev);
+
+	strcpy(t->parms.name, ip6n->fb_tnl_dev->name);
+	return 0;
+
+err_register:
+	free_netdev(ip6n->fb_tnl_dev);
+err_alloc_dev:
+	return err;
+}
+
+static void __net_exit vti6_exit_batch_net(struct list_head *net_list)
+{
+	struct vti6_net *ip6n;
+	struct net *net;
+	LIST_HEAD(list);
+
+	rtnl_lock();
+	list_for_each_entry(net, net_list, exit_list) {
+		ip6n = net_generic(net, vti6_net_id);
+		vti6_destroy_tunnels(ip6n, &list);
+	}
+	unregister_netdevice_many(&list);
+	rtnl_unlock();
+}
+
+static struct pernet_operations vti6_net_ops = {
+	.init = vti6_init_net,
+	.exit_batch = vti6_exit_batch_net,
+	.id   = &vti6_net_id,
+	.size = sizeof(struct vti6_net),
+};
+
+static struct xfrm6_protocol vti_esp6_protocol __read_mostly = {
+	.handler	=	vti6_rcv,
+	.input_handler	=	vti6_input_proto,
+	.cb_handler	=	vti6_rcv_cb,
+	.err_handler	=	vti6_err,
+	.priority	=	100,
+};
+
+static struct xfrm6_protocol vti_ah6_protocol __read_mostly = {
+	.handler	=	vti6_rcv,
+	.input_handler	=	vti6_input_proto,
+	.cb_handler	=	vti6_rcv_cb,
+	.err_handler	=	vti6_err,
+	.priority	=	100,
+};
+
+static struct xfrm6_protocol vti_ipcomp6_protocol __read_mostly = {
+	.handler	=	vti6_rcv,
+	.input_handler	=	vti6_input_proto,
+	.cb_handler	=	vti6_rcv_cb,
+	.err_handler	=	vti6_err,
+	.priority	=	100,
+};
+
+#if IS_REACHABLE(CONFIG_INET6_XFRM_TUNNEL)
+static int vti6_rcv_tunnel(struct sk_buff *skb)
+{
+	const xfrm_address_t *saddr;
+	__be32 spi;
+
+	saddr = (const xfrm_address_t *)&ipv6_hdr(skb)->saddr;
+	spi = xfrm6_tunnel_spi_lookup(dev_net(skb->dev), saddr);
+
+	return vti6_input_proto(skb, IPPROTO_IPV6, spi, 0);
+}
+
+static struct xfrm6_tunnel vti_ipv6_handler __read_mostly = {
+	.handler	=	vti6_rcv_tunnel,
+	.cb_handler	=	vti6_rcv_cb,
+	.err_handler	=	vti6_err,
+	.priority	=	0,
+};
+
+static struct xfrm6_tunnel vti_ip6ip_handler __read_mostly = {
+	.handler	=	vti6_rcv_tunnel,
+	.cb_handler	=	vti6_rcv_cb,
+	.err_handler	=	vti6_err,
+	.priority	=	0,
+};
+#endif
+
+/**
+ * vti6_tunnel_init - register protocol and reserve needed resources
+ *
+ * Return: 0 on success
+ **/
+static int __init vti6_tunnel_init(void)
+{
+	const char *msg;
+	int err;
+
+	msg = "tunnel device";
+	err = register_pernet_device(&vti6_net_ops);
+	if (err < 0)
+		goto pernet_dev_failed;
+
+	msg = "tunnel protocols";
+	err = xfrm6_protocol_register(&vti_esp6_protocol, IPPROTO_ESP);
+	if (err < 0)
+		goto xfrm_proto_esp_failed;
+	err = xfrm6_protocol_register(&vti_ah6_protocol, IPPROTO_AH);
+	if (err < 0)
+		goto xfrm_proto_ah_failed;
+	err = xfrm6_protocol_register(&vti_ipcomp6_protocol, IPPROTO_COMP);
+	if (err < 0)
+		goto xfrm_proto_comp_failed;
+#if IS_REACHABLE(CONFIG_INET6_XFRM_TUNNEL)
+	msg = "ipv6 tunnel";
+	err = xfrm6_tunnel_register(&vti_ipv6_handler, AF_INET6);
+	if (err < 0)
+		goto vti_tunnel_ipv6_failed;
+	err = xfrm6_tunnel_register(&vti_ip6ip_handler, AF_INET);
+	if (err < 0)
+		goto vti_tunnel_ip6ip_failed;
+#endif
+
+	msg = "netlink interface";
+	err = rtnl_link_register(&vti6_link_ops);
+	if (err < 0)
+		goto rtnl_link_failed;
+
+	return 0;
+
+rtnl_link_failed:
+#if IS_REACHABLE(CONFIG_INET6_XFRM_TUNNEL)
+	err = xfrm6_tunnel_deregister(&vti_ip6ip_handler, AF_INET);
+vti_tunnel_ip6ip_failed:
+	err = xfrm6_tunnel_deregister(&vti_ipv6_handler, AF_INET6);
+vti_tunnel_ipv6_failed:
+#endif
+	xfrm6_protocol_deregister(&vti_ipcomp6_protocol, IPPROTO_COMP);
+xfrm_proto_comp_failed:
+	xfrm6_protocol_deregister(&vti_ah6_protocol, IPPROTO_AH);
+xfrm_proto_ah_failed:
+	xfrm6_protocol_deregister(&vti_esp6_protocol, IPPROTO_ESP);
+xfrm_proto_esp_failed:
+	unregister_pernet_device(&vti6_net_ops);
+pernet_dev_failed:
+	pr_err("vti6 init: failed to register %s\n", msg);
+	return err;
+}
+
+/**
+ * vti6_tunnel_cleanup - free resources and unregister protocol
+ **/
+static void __exit vti6_tunnel_cleanup(void)
+{
+	rtnl_link_unregister(&vti6_link_ops);
+#if IS_REACHABLE(CONFIG_INET6_XFRM_TUNNEL)
+	xfrm6_tunnel_deregister(&vti_ip6ip_handler, AF_INET);
+	xfrm6_tunnel_deregister(&vti_ipv6_handler, AF_INET6);
+#endif
+	xfrm6_protocol_deregister(&vti_ipcomp6_protocol, IPPROTO_COMP);
+	xfrm6_protocol_deregister(&vti_ah6_protocol, IPPROTO_AH);
+	xfrm6_protocol_deregister(&vti_esp6_protocol, IPPROTO_ESP);
+	unregister_pernet_device(&vti6_net_ops);
+}
+
+module_init(vti6_tunnel_init);
+module_exit(vti6_tunnel_cleanup);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_RTNL_LINK("vti6");
+MODULE_ALIAS_NETDEV("ip6_vti0");
+MODULE_AUTHOR("Steffen Klassert");
+MODULE_DESCRIPTION("IPv6 virtual tunnel interface");