Adding upstream version 4.19.249.upstream/4.19.249upstream

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

1 files changed, 1966 insertions, 0 deletions

diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
new file mode 100644
index 000000000..55c999cbe
--- /dev/null
+++ b/net/ipv6/sit.c
@@ -0,0 +1,1966 @@
+/*
+ *	IPv6 over IPv4 tunnel device - Simple Internet Transition (SIT)
+ *	Linux INET6 implementation
+ *
+ *	Authors:
+ *	Pedro Roque		<roque@di.fc.ul.pt>
+ *	Alexey Kuznetsov	<kuznet@ms2.inr.ac.ru>
+ *
+ *	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.
+ *
+ *	Changes:
+ * Roger Venning <r.venning@telstra.com>:	6to4 support
+ * Nate Thompson <nate@thebog.net>:		6to4 support
+ * Fred Templin <fred.l.templin@boeing.com>:	isatap support
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/capability.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <linux/in6.h>
+#include <linux/netdevice.h>
+#include <linux/if_arp.h>
+#include <linux/icmp.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/init.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/if_ether.h>
+
+#include <net/sock.h>
+#include <net/snmp.h>
+
+#include <net/ipv6.h>
+#include <net/protocol.h>
+#include <net/transp_v6.h>
+#include <net/ip6_fib.h>
+#include <net/ip6_route.h>
+#include <net/ndisc.h>
+#include <net/addrconf.h>
+#include <net/ip.h>
+#include <net/udp.h>
+#include <net/icmp.h>
+#include <net/ip_tunnels.h>
+#include <net/inet_ecn.h>
+#include <net/xfrm.h>
+#include <net/dsfield.h>
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
+
+/*
+   This version of net/ipv6/sit.c is cloned of net/ipv4/ip_gre.c
+
+   For comments look at net/ipv4/ip_gre.c --ANK
+ */
+
+#define IP6_SIT_HASH_SIZE  16
+#define HASH(addr) (((__force u32)addr^((__force u32)addr>>4))&0xF)
+
+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 int ipip6_tunnel_init(struct net_device *dev);
+static void ipip6_tunnel_setup(struct net_device *dev);
+static void ipip6_dev_free(struct net_device *dev);
+static bool check_6rd(struct ip_tunnel *tunnel, const struct in6_addr *v6dst,
+		      __be32 *v4dst);
+static struct rtnl_link_ops sit_link_ops __read_mostly;
+
+static unsigned int sit_net_id __read_mostly;
+struct sit_net {
+	struct ip_tunnel __rcu *tunnels_r_l[IP6_SIT_HASH_SIZE];
+	struct ip_tunnel __rcu *tunnels_r[IP6_SIT_HASH_SIZE];
+	struct ip_tunnel __rcu *tunnels_l[IP6_SIT_HASH_SIZE];
+	struct ip_tunnel __rcu *tunnels_wc[1];
+	struct ip_tunnel __rcu **tunnels[4];
+
+	struct net_device *fb_tunnel_dev;
+};
+
+/*
+ * Must be invoked with rcu_read_lock
+ */
+static struct ip_tunnel *ipip6_tunnel_lookup(struct net *net,
+					     struct net_device *dev,
+					     __be32 remote, __be32 local,
+					     int sifindex)
+{
+	unsigned int h0 = HASH(remote);
+	unsigned int h1 = HASH(local);
+	struct ip_tunnel *t;
+	struct sit_net *sitn = net_generic(net, sit_net_id);
+	int ifindex = dev ? dev->ifindex : 0;
+
+	for_each_ip_tunnel_rcu(t, sitn->tunnels_r_l[h0 ^ h1]) {
+		if (local == t->parms.iph.saddr &&
+		    remote == t->parms.iph.daddr &&
+		    (!dev || !t->parms.link || ifindex == t->parms.link ||
+		     sifindex == t->parms.link) &&
+		    (t->dev->flags & IFF_UP))
+			return t;
+	}
+	for_each_ip_tunnel_rcu(t, sitn->tunnels_r[h0]) {
+		if (remote == t->parms.iph.daddr &&
+		    (!dev || !t->parms.link || ifindex == t->parms.link ||
+		     sifindex == t->parms.link) &&
+		    (t->dev->flags & IFF_UP))
+			return t;
+	}
+	for_each_ip_tunnel_rcu(t, sitn->tunnels_l[h1]) {
+		if (local == t->parms.iph.saddr &&
+		    (!dev || !t->parms.link || ifindex == t->parms.link ||
+		     sifindex == t->parms.link) &&
+		    (t->dev->flags & IFF_UP))
+			return t;
+	}
+	t = rcu_dereference(sitn->tunnels_wc[0]);
+	if (t && (t->dev->flags & IFF_UP))
+		return t;
+	return NULL;
+}
+
+static struct ip_tunnel __rcu **__ipip6_bucket(struct sit_net *sitn,
+		struct ip_tunnel_parm *parms)
+{
+	__be32 remote = parms->iph.daddr;
+	__be32 local = parms->iph.saddr;
+	unsigned int h = 0;
+	int prio = 0;
+
+	if (remote) {
+		prio |= 2;
+		h ^= HASH(remote);
+	}
+	if (local) {
+		prio |= 1;
+		h ^= HASH(local);
+	}
+	return &sitn->tunnels[prio][h];
+}
+
+static inline struct ip_tunnel __rcu **ipip6_bucket(struct sit_net *sitn,
+		struct ip_tunnel *t)
+{
+	return __ipip6_bucket(sitn, &t->parms);
+}
+
+static void ipip6_tunnel_unlink(struct sit_net *sitn, struct ip_tunnel *t)
+{
+	struct ip_tunnel __rcu **tp;
+	struct ip_tunnel *iter;
+
+	for (tp = ipip6_bucket(sitn, t);
+	     (iter = rtnl_dereference(*tp)) != NULL;
+	     tp = &iter->next) {
+		if (t == iter) {
+			rcu_assign_pointer(*tp, t->next);
+			break;
+		}
+	}
+}
+
+static void ipip6_tunnel_link(struct sit_net *sitn, struct ip_tunnel *t)
+{
+	struct ip_tunnel __rcu **tp = ipip6_bucket(sitn, t);
+
+	rcu_assign_pointer(t->next, rtnl_dereference(*tp));
+	rcu_assign_pointer(*tp, t);
+}
+
+static void ipip6_tunnel_clone_6rd(struct net_device *dev, struct sit_net *sitn)
+{
+#ifdef CONFIG_IPV6_SIT_6RD
+	struct ip_tunnel *t = netdev_priv(dev);
+
+	if (dev == sitn->fb_tunnel_dev || !sitn->fb_tunnel_dev) {
+		ipv6_addr_set(&t->ip6rd.prefix, htonl(0x20020000), 0, 0, 0);
+		t->ip6rd.relay_prefix = 0;
+		t->ip6rd.prefixlen = 16;
+		t->ip6rd.relay_prefixlen = 0;
+	} else {
+		struct ip_tunnel *t0 = netdev_priv(sitn->fb_tunnel_dev);
+		memcpy(&t->ip6rd, &t0->ip6rd, sizeof(t->ip6rd));
+	}
+#endif
+}
+
+static int ipip6_tunnel_create(struct net_device *dev)
+{
+	struct ip_tunnel *t = netdev_priv(dev);
+	struct net *net = dev_net(dev);
+	struct sit_net *sitn = net_generic(net, sit_net_id);
+	int err;
+
+	memcpy(dev->dev_addr, &t->parms.iph.saddr, 4);
+	memcpy(dev->broadcast, &t->parms.iph.daddr, 4);
+
+	if ((__force u16)t->parms.i_flags & SIT_ISATAP)
+		dev->priv_flags |= IFF_ISATAP;
+
+	dev->rtnl_link_ops = &sit_link_ops;
+
+	err = register_netdevice(dev);
+	if (err < 0)
+		goto out;
+
+	ipip6_tunnel_clone_6rd(dev, sitn);
+
+	ipip6_tunnel_link(sitn, t);
+	return 0;
+
+out:
+	return err;
+}
+
+static struct ip_tunnel *ipip6_tunnel_locate(struct net *net,
+		struct ip_tunnel_parm *parms, int create)
+{
+	__be32 remote = parms->iph.daddr;
+	__be32 local = parms->iph.saddr;
+	struct ip_tunnel *t, *nt;
+	struct ip_tunnel __rcu **tp;
+	struct net_device *dev;
+	char name[IFNAMSIZ];
+	struct sit_net *sitn = net_generic(net, sit_net_id);
+
+	for (tp = __ipip6_bucket(sitn, parms);
+	    (t = rtnl_dereference(*tp)) != NULL;
+	     tp = &t->next) {
+		if (local == t->parms.iph.saddr &&
+		    remote == t->parms.iph.daddr &&
+		    parms->link == t->parms.link) {
+			if (create)
+				return NULL;
+			else
+				return t;
+		}
+	}
+	if (!create)
+		goto failed;
+
+	if (parms->name[0]) {
+		if (!dev_valid_name(parms->name))
+			goto failed;
+		strlcpy(name, parms->name, IFNAMSIZ);
+	} else {
+		strcpy(name, "sit%d");
+	}
+	dev = alloc_netdev(sizeof(*t), name, NET_NAME_UNKNOWN,
+			   ipip6_tunnel_setup);
+	if (!dev)
+		return NULL;
+
+	dev_net_set(dev, net);
+
+	nt = netdev_priv(dev);
+
+	nt->parms = *parms;
+	if (ipip6_tunnel_create(dev) < 0)
+		goto failed_free;
+
+	return nt;
+
+failed_free:
+	free_netdev(dev);
+failed:
+	return NULL;
+}
+
+#define for_each_prl_rcu(start)			\
+	for (prl = rcu_dereference(start);	\
+	     prl;				\
+	     prl = rcu_dereference(prl->next))
+
+static struct ip_tunnel_prl_entry *
+__ipip6_tunnel_locate_prl(struct ip_tunnel *t, __be32 addr)
+{
+	struct ip_tunnel_prl_entry *prl;
+
+	for_each_prl_rcu(t->prl)
+		if (prl->addr == addr)
+			break;
+	return prl;
+
+}
+
+static int ipip6_tunnel_get_prl(struct ip_tunnel *t,
+				struct ip_tunnel_prl __user *a)
+{
+	struct ip_tunnel_prl kprl, *kp;
+	struct ip_tunnel_prl_entry *prl;
+	unsigned int cmax, c = 0, ca, len;
+	int ret = 0;
+
+	if (copy_from_user(&kprl, a, sizeof(kprl)))
+		return -EFAULT;
+	cmax = kprl.datalen / sizeof(kprl);
+	if (cmax > 1 && kprl.addr != htonl(INADDR_ANY))
+		cmax = 1;
+
+	/* For simple GET or for root users,
+	 * we try harder to allocate.
+	 */
+	kp = (cmax <= 1 || capable(CAP_NET_ADMIN)) ?
+		kcalloc(cmax, sizeof(*kp), GFP_KERNEL | __GFP_NOWARN) :
+		NULL;
+
+	rcu_read_lock();
+
+	ca = t->prl_count < cmax ? t->prl_count : cmax;
+
+	if (!kp) {
+		/* We don't try hard to allocate much memory for
+		 * non-root users.
+		 * For root users, retry allocating enough memory for
+		 * the answer.
+		 */
+		kp = kcalloc(ca, sizeof(*kp), GFP_ATOMIC);
+		if (!kp) {
+			ret = -ENOMEM;
+			goto out;
+		}
+	}
+
+	c = 0;
+	for_each_prl_rcu(t->prl) {
+		if (c >= cmax)
+			break;
+		if (kprl.addr != htonl(INADDR_ANY) && prl->addr != kprl.addr)
+			continue;
+		kp[c].addr = prl->addr;
+		kp[c].flags = prl->flags;
+		c++;
+		if (kprl.addr != htonl(INADDR_ANY))
+			break;
+	}
+out:
+	rcu_read_unlock();
+
+	len = sizeof(*kp) * c;
+	ret = 0;
+	if ((len && copy_to_user(a + 1, kp, len)) || put_user(len, &a->datalen))
+		ret = -EFAULT;
+
+	kfree(kp);
+
+	return ret;
+}
+
+static int
+ipip6_tunnel_add_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a, int chg)
+{
+	struct ip_tunnel_prl_entry *p;
+	int err = 0;
+
+	if (a->addr == htonl(INADDR_ANY))
+		return -EINVAL;
+
+	ASSERT_RTNL();
+
+	for (p = rtnl_dereference(t->prl); p; p = rtnl_dereference(p->next)) {
+		if (p->addr == a->addr) {
+			if (chg) {
+				p->flags = a->flags;
+				goto out;
+			}
+			err = -EEXIST;
+			goto out;
+		}
+	}
+
+	if (chg) {
+		err = -ENXIO;
+		goto out;
+	}
+
+	p = kzalloc(sizeof(struct ip_tunnel_prl_entry), GFP_KERNEL);
+	if (!p) {
+		err = -ENOBUFS;
+		goto out;
+	}
+
+	p->next = t->prl;
+	p->addr = a->addr;
+	p->flags = a->flags;
+	t->prl_count++;
+	rcu_assign_pointer(t->prl, p);
+out:
+	return err;
+}
+
+static void prl_list_destroy_rcu(struct rcu_head *head)
+{
+	struct ip_tunnel_prl_entry *p, *n;
+
+	p = container_of(head, struct ip_tunnel_prl_entry, rcu_head);
+	do {
+		n = rcu_dereference_protected(p->next, 1);
+		kfree(p);
+		p = n;
+	} while (p);
+}
+
+static int
+ipip6_tunnel_del_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a)
+{
+	struct ip_tunnel_prl_entry *x;
+	struct ip_tunnel_prl_entry __rcu **p;
+	int err = 0;
+
+	ASSERT_RTNL();
+
+	if (a && a->addr != htonl(INADDR_ANY)) {
+		for (p = &t->prl;
+		     (x = rtnl_dereference(*p)) != NULL;
+		     p = &x->next) {
+			if (x->addr == a->addr) {
+				*p = x->next;
+				kfree_rcu(x, rcu_head);
+				t->prl_count--;
+				goto out;
+			}
+		}
+		err = -ENXIO;
+	} else {
+		x = rtnl_dereference(t->prl);
+		if (x) {
+			t->prl_count = 0;
+			call_rcu(&x->rcu_head, prl_list_destroy_rcu);
+			t->prl = NULL;
+		}
+	}
+out:
+	return err;
+}
+
+static int
+isatap_chksrc(struct sk_buff *skb, const struct iphdr *iph, struct ip_tunnel *t)
+{
+	struct ip_tunnel_prl_entry *p;
+	int ok = 1;
+
+	rcu_read_lock();
+	p = __ipip6_tunnel_locate_prl(t, iph->saddr);
+	if (p) {
+		if (p->flags & PRL_DEFAULT)
+			skb->ndisc_nodetype = NDISC_NODETYPE_DEFAULT;
+		else
+			skb->ndisc_nodetype = NDISC_NODETYPE_NODEFAULT;
+	} else {
+		const struct in6_addr *addr6 = &ipv6_hdr(skb)->saddr;
+
+		if (ipv6_addr_is_isatap(addr6) &&
+		    (addr6->s6_addr32[3] == iph->saddr) &&
+		    ipv6_chk_prefix(addr6, t->dev))
+			skb->ndisc_nodetype = NDISC_NODETYPE_HOST;
+		else
+			ok = 0;
+	}
+	rcu_read_unlock();
+	return ok;
+}
+
+static void ipip6_tunnel_uninit(struct net_device *dev)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+	struct sit_net *sitn = net_generic(tunnel->net, sit_net_id);
+
+	if (dev == sitn->fb_tunnel_dev) {
+		RCU_INIT_POINTER(sitn->tunnels_wc[0], NULL);
+	} else {
+		ipip6_tunnel_unlink(sitn, tunnel);
+		ipip6_tunnel_del_prl(tunnel, NULL);
+	}
+	dst_cache_reset(&tunnel->dst_cache);
+	dev_put(dev);
+}
+
+static int ipip6_err(struct sk_buff *skb, u32 info)
+{
+	const struct iphdr *iph = (const struct iphdr *)skb->data;
+	const int type = icmp_hdr(skb)->type;
+	const int code = icmp_hdr(skb)->code;
+	unsigned int data_len = 0;
+	struct ip_tunnel *t;
+	int sifindex;
+	int err;
+
+	switch (type) {
+	default:
+	case ICMP_PARAMETERPROB:
+		return 0;
+
+	case ICMP_DEST_UNREACH:
+		switch (code) {
+		case ICMP_SR_FAILED:
+			/* 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;
+	}
+
+	err = -ENOENT;
+
+	sifindex = netif_is_l3_master(skb->dev) ? IPCB(skb)->iif : 0;
+	t = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
+				iph->daddr, iph->saddr, sifindex);
+	if (!t)
+		goto out;
+
+	if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
+		ipv4_update_pmtu(skb, dev_net(skb->dev), info,
+				 t->parms.link, 0, iph->protocol, 0);
+		err = 0;
+		goto out;
+	}
+	if (type == ICMP_REDIRECT) {
+		ipv4_redirect(skb, dev_net(skb->dev), t->parms.link, 0,
+			      iph->protocol, 0);
+		err = 0;
+		goto out;
+	}
+
+	err = 0;
+	if (__in6_dev_get(skb->dev) &&
+	    !ip6_err_gen_icmpv6_unreach(skb, iph->ihl * 4, type, data_len))
+		goto out;
+
+	if (t->parms.iph.daddr == 0)
+		goto out;
+
+	if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
+		goto out;
+
+	if (time_before(jiffies, t->err_time + IPTUNNEL_ERR_TIMEO))
+		t->err_count++;
+	else
+		t->err_count = 1;
+	t->err_time = jiffies;
+out:
+	return err;
+}
+
+static inline bool is_spoofed_6rd(struct ip_tunnel *tunnel, const __be32 v4addr,
+				  const struct in6_addr *v6addr)
+{
+	__be32 v4embed = 0;
+	if (check_6rd(tunnel, v6addr, &v4embed) && v4addr != v4embed)
+		return true;
+	return false;
+}
+
+/* Checks if an address matches an address on the tunnel interface.
+ * Used to detect the NAT of proto 41 packets and let them pass spoofing test.
+ * Long story:
+ * This function is called after we considered the packet as spoofed
+ * in is_spoofed_6rd.
+ * We may have a router that is doing NAT for proto 41 packets
+ * for an internal station. Destination a.a.a.a/PREFIX:bbbb:bbbb
+ * will be translated to n.n.n.n/PREFIX:bbbb:bbbb. And is_spoofed_6rd
+ * function will return true, dropping the packet.
+ * But, we can still check if is spoofed against the IP
+ * addresses associated with the interface.
+ */
+static bool only_dnatted(const struct ip_tunnel *tunnel,
+	const struct in6_addr *v6dst)
+{
+	int prefix_len;
+
+#ifdef CONFIG_IPV6_SIT_6RD
+	prefix_len = tunnel->ip6rd.prefixlen + 32
+		- tunnel->ip6rd.relay_prefixlen;
+#else
+	prefix_len = 48;
+#endif
+	return ipv6_chk_custom_prefix(v6dst, prefix_len, tunnel->dev);
+}
+
+/* Returns true if a packet is spoofed */
+static bool packet_is_spoofed(struct sk_buff *skb,
+			      const struct iphdr *iph,
+			      struct ip_tunnel *tunnel)
+{
+	const struct ipv6hdr *ipv6h;
+
+	if (tunnel->dev->priv_flags & IFF_ISATAP) {
+		if (!isatap_chksrc(skb, iph, tunnel))
+			return true;
+
+		return false;
+	}
+
+	if (tunnel->dev->flags & IFF_POINTOPOINT)
+		return false;
+
+	ipv6h = ipv6_hdr(skb);
+
+	if (unlikely(is_spoofed_6rd(tunnel, iph->saddr, &ipv6h->saddr))) {
+		net_warn_ratelimited("Src spoofed %pI4/%pI6c -> %pI4/%pI6c\n",
+				     &iph->saddr, &ipv6h->saddr,
+				     &iph->daddr, &ipv6h->daddr);
+		return true;
+	}
+
+	if (likely(!is_spoofed_6rd(tunnel, iph->daddr, &ipv6h->daddr)))
+		return false;
+
+	if (only_dnatted(tunnel, &ipv6h->daddr))
+		return false;
+
+	net_warn_ratelimited("Dst spoofed %pI4/%pI6c -> %pI4/%pI6c\n",
+			     &iph->saddr, &ipv6h->saddr,
+			     &iph->daddr, &ipv6h->daddr);
+	return true;
+}
+
+static int ipip6_rcv(struct sk_buff *skb)
+{
+	const struct iphdr *iph = ip_hdr(skb);
+	struct ip_tunnel *tunnel;
+	int sifindex;
+	int err;
+
+	sifindex = netif_is_l3_master(skb->dev) ? IPCB(skb)->iif : 0;
+	tunnel = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
+				     iph->saddr, iph->daddr, sifindex);
+	if (tunnel) {
+		struct pcpu_sw_netstats *tstats;
+
+		if (tunnel->parms.iph.protocol != IPPROTO_IPV6 &&
+		    tunnel->parms.iph.protocol != 0)
+			goto out;
+
+		skb->mac_header = skb->network_header;
+		skb_reset_network_header(skb);
+		IPCB(skb)->flags = 0;
+		skb->dev = tunnel->dev;
+
+		if (packet_is_spoofed(skb, iph, tunnel)) {
+			tunnel->dev->stats.rx_errors++;
+			goto out;
+		}
+
+		if (iptunnel_pull_header(skb, 0, htons(ETH_P_IPV6),
+		    !net_eq(tunnel->net, dev_net(tunnel->dev))))
+			goto out;
+
+		/* skb can be uncloned in iptunnel_pull_header, so
+		 * old iph is no longer valid
+		 */
+		iph = (const struct iphdr *)skb_mac_header(skb);
+		err = IP_ECN_decapsulate(iph, skb);
+		if (unlikely(err)) {
+			if (log_ecn_error)
+				net_info_ratelimited("non-ECT from %pI4 with TOS=%#x\n",
+						     &iph->saddr, iph->tos);
+			if (err > 1) {
+				++tunnel->dev->stats.rx_frame_errors;
+				++tunnel->dev->stats.rx_errors;
+				goto out;
+			}
+		}
+
+		tstats = this_cpu_ptr(tunnel->dev->tstats);
+		u64_stats_update_begin(&tstats->syncp);
+		tstats->rx_packets++;
+		tstats->rx_bytes += skb->len;
+		u64_stats_update_end(&tstats->syncp);
+
+		netif_rx(skb);
+
+		return 0;
+	}
+
+	/* no tunnel matched,  let upstream know, ipsec may handle it */
+	return 1;
+out:
+	kfree_skb(skb);
+	return 0;
+}
+
+static const struct tnl_ptk_info ipip_tpi = {
+	/* no tunnel info required for ipip. */
+	.proto = htons(ETH_P_IP),
+};
+
+#if IS_ENABLED(CONFIG_MPLS)
+static const struct tnl_ptk_info mplsip_tpi = {
+	/* no tunnel info required for mplsip. */
+	.proto = htons(ETH_P_MPLS_UC),
+};
+#endif
+
+static int sit_tunnel_rcv(struct sk_buff *skb, u8 ipproto)
+{
+	const struct iphdr *iph;
+	struct ip_tunnel *tunnel;
+	int sifindex;
+
+	sifindex = netif_is_l3_master(skb->dev) ? IPCB(skb)->iif : 0;
+
+	iph = ip_hdr(skb);
+	tunnel = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
+				     iph->saddr, iph->daddr, sifindex);
+	if (tunnel) {
+		const struct tnl_ptk_info *tpi;
+
+		if (tunnel->parms.iph.protocol != ipproto &&
+		    tunnel->parms.iph.protocol != 0)
+			goto drop;
+
+		if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
+			goto drop;
+#if IS_ENABLED(CONFIG_MPLS)
+		if (ipproto == IPPROTO_MPLS)
+			tpi = &mplsip_tpi;
+		else
+#endif
+			tpi = &ipip_tpi;
+		if (iptunnel_pull_header(skb, 0, tpi->proto, false))
+			goto drop;
+		return ip_tunnel_rcv(tunnel, skb, tpi, NULL, log_ecn_error);
+	}
+
+	return 1;
+
+drop:
+	kfree_skb(skb);
+	return 0;
+}
+
+static int ipip_rcv(struct sk_buff *skb)
+{
+	return sit_tunnel_rcv(skb, IPPROTO_IPIP);
+}
+
+#if IS_ENABLED(CONFIG_MPLS)
+static int mplsip_rcv(struct sk_buff *skb)
+{
+	return sit_tunnel_rcv(skb, IPPROTO_MPLS);
+}
+#endif
+
+/*
+ * If the IPv6 address comes from 6rd / 6to4 (RFC 3056) addr space this function
+ * stores the embedded IPv4 address in v4dst and returns true.
+ */
+static bool check_6rd(struct ip_tunnel *tunnel, const struct in6_addr *v6dst,
+		      __be32 *v4dst)
+{
+#ifdef CONFIG_IPV6_SIT_6RD
+	if (ipv6_prefix_equal(v6dst, &tunnel->ip6rd.prefix,
+			      tunnel->ip6rd.prefixlen)) {
+		unsigned int pbw0, pbi0;
+		int pbi1;
+		u32 d;
+
+		pbw0 = tunnel->ip6rd.prefixlen >> 5;
+		pbi0 = tunnel->ip6rd.prefixlen & 0x1f;
+
+		d = tunnel->ip6rd.relay_prefixlen < 32 ?
+			(ntohl(v6dst->s6_addr32[pbw0]) << pbi0) >>
+		    tunnel->ip6rd.relay_prefixlen : 0;
+
+		pbi1 = pbi0 - tunnel->ip6rd.relay_prefixlen;
+		if (pbi1 > 0)
+			d |= ntohl(v6dst->s6_addr32[pbw0 + 1]) >>
+			     (32 - pbi1);
+
+		*v4dst = tunnel->ip6rd.relay_prefix | htonl(d);
+		return true;
+	}
+#else
+	if (v6dst->s6_addr16[0] == htons(0x2002)) {
+		/* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
+		memcpy(v4dst, &v6dst->s6_addr16[1], 4);
+		return true;
+	}
+#endif
+	return false;
+}
+
+static inline __be32 try_6rd(struct ip_tunnel *tunnel,
+			     const struct in6_addr *v6dst)
+{
+	__be32 dst = 0;
+	check_6rd(tunnel, v6dst, &dst);
+	return dst;
+}
+
+/*
+ *	This function assumes it is being called from dev_queue_xmit()
+ *	and that skb is filled properly by that function.
+ */
+
+static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
+				     struct net_device *dev)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+	const struct iphdr  *tiph = &tunnel->parms.iph;
+	const struct ipv6hdr *iph6 = ipv6_hdr(skb);
+	u8     tos = tunnel->parms.iph.tos;
+	__be16 df = tiph->frag_off;
+	struct rtable *rt;		/* Route to the other host */
+	struct net_device *tdev;	/* Device to other host */
+	unsigned int max_headroom;	/* The extra header space needed */
+	__be32 dst = tiph->daddr;
+	struct flowi4 fl4;
+	int    mtu;
+	const struct in6_addr *addr6;
+	int addr_type;
+	u8 ttl;
+	u8 protocol = IPPROTO_IPV6;
+	int t_hlen = tunnel->hlen + sizeof(struct iphdr);
+
+	if (tos == 1)
+		tos = ipv6_get_dsfield(iph6);
+
+	/* ISATAP (RFC4214) - must come before 6to4 */
+	if (dev->priv_flags & IFF_ISATAP) {
+		struct neighbour *neigh = NULL;
+		bool do_tx_error = false;
+
+		if (skb_dst(skb))
+			neigh = dst_neigh_lookup(skb_dst(skb), &iph6->daddr);
+
+		if (!neigh) {
+			net_dbg_ratelimited("nexthop == NULL\n");
+			goto tx_error;
+		}
+
+		addr6 = (const struct in6_addr *)&neigh->primary_key;
+		addr_type = ipv6_addr_type(addr6);
+
+		if ((addr_type & IPV6_ADDR_UNICAST) &&
+		     ipv6_addr_is_isatap(addr6))
+			dst = addr6->s6_addr32[3];
+		else
+			do_tx_error = true;
+
+		neigh_release(neigh);
+		if (do_tx_error)
+			goto tx_error;
+	}
+
+	if (!dst)
+		dst = try_6rd(tunnel, &iph6->daddr);
+
+	if (!dst) {
+		struct neighbour *neigh = NULL;
+		bool do_tx_error = false;
+
+		if (skb_dst(skb))
+			neigh = dst_neigh_lookup(skb_dst(skb), &iph6->daddr);
+
+		if (!neigh) {
+			net_dbg_ratelimited("nexthop == NULL\n");
+			goto tx_error;
+		}
+
+		addr6 = (const struct in6_addr *)&neigh->primary_key;
+		addr_type = ipv6_addr_type(addr6);
+
+		if (addr_type == IPV6_ADDR_ANY) {
+			addr6 = &ipv6_hdr(skb)->daddr;
+			addr_type = ipv6_addr_type(addr6);
+		}
+
+		if ((addr_type & IPV6_ADDR_COMPATv4) != 0)
+			dst = addr6->s6_addr32[3];
+		else
+			do_tx_error = true;
+
+		neigh_release(neigh);
+		if (do_tx_error)
+			goto tx_error;
+	}
+
+	flowi4_init_output(&fl4, tunnel->parms.link, tunnel->fwmark,
+			   RT_TOS(tos), RT_SCOPE_UNIVERSE, IPPROTO_IPV6,
+			   0, dst, tiph->saddr, 0, 0,
+			   sock_net_uid(tunnel->net, NULL));
+	rt = ip_route_output_flow(tunnel->net, &fl4, NULL);
+
+	if (IS_ERR(rt)) {
+		dev->stats.tx_carrier_errors++;
+		goto tx_error_icmp;
+	}
+	if (rt->rt_type != RTN_UNICAST) {
+		ip_rt_put(rt);
+		dev->stats.tx_carrier_errors++;
+		goto tx_error_icmp;
+	}
+	tdev = rt->dst.dev;
+
+	if (tdev == dev) {
+		ip_rt_put(rt);
+		dev->stats.collisions++;
+		goto tx_error;
+	}
+
+	if (iptunnel_handle_offloads(skb, SKB_GSO_IPXIP4)) {
+		ip_rt_put(rt);
+		goto tx_error;
+	}
+
+	if (df) {
+		mtu = dst_mtu(&rt->dst) - t_hlen;
+
+		if (mtu < 68) {
+			dev->stats.collisions++;
+			ip_rt_put(rt);
+			goto tx_error;
+		}
+
+		if (mtu < IPV6_MIN_MTU) {
+			mtu = IPV6_MIN_MTU;
+			df = 0;
+		}
+
+		if (tunnel->parms.iph.daddr)
+			skb_dst_update_pmtu_no_confirm(skb, mtu);
+
+		if (skb->len > mtu && !skb_is_gso(skb)) {
+			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
+			ip_rt_put(rt);
+			goto tx_error;
+		}
+	}
+
+	if (tunnel->err_count > 0) {
+		if (time_before(jiffies,
+				tunnel->err_time + IPTUNNEL_ERR_TIMEO)) {
+			tunnel->err_count--;
+			dst_link_failure(skb);
+		} else
+			tunnel->err_count = 0;
+	}
+
+	/*
+	 * Okay, now see if we can stuff it in the buffer as-is.
+	 */
+	max_headroom = LL_RESERVED_SPACE(tdev) + t_hlen;
+
+	if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
+	    (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
+		struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
+		if (!new_skb) {
+			ip_rt_put(rt);
+			dev->stats.tx_dropped++;
+			kfree_skb(skb);
+			return NETDEV_TX_OK;
+		}
+		if (skb->sk)
+			skb_set_owner_w(new_skb, skb->sk);
+		dev_kfree_skb(skb);
+		skb = new_skb;
+		iph6 = ipv6_hdr(skb);
+	}
+	ttl = tiph->ttl;
+	if (ttl == 0)
+		ttl = iph6->hop_limit;
+	tos = INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
+
+	if (ip_tunnel_encap(skb, tunnel, &protocol, &fl4) < 0) {
+		ip_rt_put(rt);
+		goto tx_error;
+	}
+
+	skb_set_inner_ipproto(skb, IPPROTO_IPV6);
+
+	iptunnel_xmit(NULL, rt, skb, fl4.saddr, fl4.daddr, protocol, tos, ttl,
+		      df, !net_eq(tunnel->net, dev_net(dev)));
+	return NETDEV_TX_OK;
+
+tx_error_icmp:
+	dst_link_failure(skb);
+tx_error:
+	kfree_skb(skb);
+	dev->stats.tx_errors++;
+	return NETDEV_TX_OK;
+}
+
+static netdev_tx_t sit_tunnel_xmit__(struct sk_buff *skb,
+				     struct net_device *dev, u8 ipproto)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+	const struct iphdr  *tiph = &tunnel->parms.iph;
+
+	if (iptunnel_handle_offloads(skb, SKB_GSO_IPXIP4))
+		goto tx_error;
+
+	skb_set_inner_ipproto(skb, ipproto);
+
+	ip_tunnel_xmit(skb, dev, tiph, ipproto);
+	return NETDEV_TX_OK;
+tx_error:
+	kfree_skb(skb);
+	dev->stats.tx_errors++;
+	return NETDEV_TX_OK;
+}
+
+static netdev_tx_t sit_tunnel_xmit(struct sk_buff *skb,
+				   struct net_device *dev)
+{
+	if (!pskb_inet_may_pull(skb))
+		goto tx_err;
+
+	switch (skb->protocol) {
+	case htons(ETH_P_IP):
+		sit_tunnel_xmit__(skb, dev, IPPROTO_IPIP);
+		break;
+	case htons(ETH_P_IPV6):
+		ipip6_tunnel_xmit(skb, dev);
+		break;
+#if IS_ENABLED(CONFIG_MPLS)
+	case htons(ETH_P_MPLS_UC):
+		sit_tunnel_xmit__(skb, dev, IPPROTO_MPLS);
+		break;
+#endif
+	default:
+		goto tx_err;
+	}
+
+	return NETDEV_TX_OK;
+
+tx_err:
+	dev->stats.tx_errors++;
+	kfree_skb(skb);
+	return NETDEV_TX_OK;
+
+}
+
+static void ipip6_tunnel_bind_dev(struct net_device *dev)
+{
+	struct net_device *tdev = NULL;
+	struct ip_tunnel *tunnel;
+	const struct iphdr *iph;
+	struct flowi4 fl4;
+
+	tunnel = netdev_priv(dev);
+	iph = &tunnel->parms.iph;
+
+	if (iph->daddr) {
+		struct rtable *rt = ip_route_output_ports(tunnel->net, &fl4,
+							  NULL,
+							  iph->daddr, iph->saddr,
+							  0, 0,
+							  IPPROTO_IPV6,
+							  RT_TOS(iph->tos),
+							  tunnel->parms.link);
+
+		if (!IS_ERR(rt)) {
+			tdev = rt->dst.dev;
+			ip_rt_put(rt);
+		}
+		dev->flags |= IFF_POINTOPOINT;
+	}
+
+	if (!tdev && tunnel->parms.link)
+		tdev = __dev_get_by_index(tunnel->net, tunnel->parms.link);
+
+	if (tdev && !netif_is_l3_master(tdev)) {
+		int t_hlen = tunnel->hlen + sizeof(struct iphdr);
+
+		dev->mtu = tdev->mtu - t_hlen;
+		if (dev->mtu < IPV6_MIN_MTU)
+			dev->mtu = IPV6_MIN_MTU;
+	}
+}
+
+static void ipip6_tunnel_update(struct ip_tunnel *t, struct ip_tunnel_parm *p,
+				__u32 fwmark)
+{
+	struct net *net = t->net;
+	struct sit_net *sitn = net_generic(net, sit_net_id);
+
+	ipip6_tunnel_unlink(sitn, t);
+	synchronize_net();
+	t->parms.iph.saddr = p->iph.saddr;
+	t->parms.iph.daddr = p->iph.daddr;
+	memcpy(t->dev->dev_addr, &p->iph.saddr, 4);
+	memcpy(t->dev->broadcast, &p->iph.daddr, 4);
+	ipip6_tunnel_link(sitn, t);
+	t->parms.iph.ttl = p->iph.ttl;
+	t->parms.iph.tos = p->iph.tos;
+	t->parms.iph.frag_off = p->iph.frag_off;
+	if (t->parms.link != p->link || t->fwmark != fwmark) {
+		t->parms.link = p->link;
+		t->fwmark = fwmark;
+		ipip6_tunnel_bind_dev(t->dev);
+	}
+	dst_cache_reset(&t->dst_cache);
+	netdev_state_change(t->dev);
+}
+
+#ifdef CONFIG_IPV6_SIT_6RD
+static int ipip6_tunnel_update_6rd(struct ip_tunnel *t,
+				   struct ip_tunnel_6rd *ip6rd)
+{
+	struct in6_addr prefix;
+	__be32 relay_prefix;
+
+	if (ip6rd->relay_prefixlen > 32 ||
+	    ip6rd->prefixlen + (32 - ip6rd->relay_prefixlen) > 64)
+		return -EINVAL;
+
+	ipv6_addr_prefix(&prefix, &ip6rd->prefix, ip6rd->prefixlen);
+	if (!ipv6_addr_equal(&prefix, &ip6rd->prefix))
+		return -EINVAL;
+	if (ip6rd->relay_prefixlen)
+		relay_prefix = ip6rd->relay_prefix &
+			       htonl(0xffffffffUL <<
+				     (32 - ip6rd->relay_prefixlen));
+	else
+		relay_prefix = 0;
+	if (relay_prefix != ip6rd->relay_prefix)
+		return -EINVAL;
+
+	t->ip6rd.prefix = prefix;
+	t->ip6rd.relay_prefix = relay_prefix;
+	t->ip6rd.prefixlen = ip6rd->prefixlen;
+	t->ip6rd.relay_prefixlen = ip6rd->relay_prefixlen;
+	dst_cache_reset(&t->dst_cache);
+	netdev_state_change(t->dev);
+	return 0;
+}
+#endif
+
+static bool ipip6_valid_ip_proto(u8 ipproto)
+{
+	return ipproto == IPPROTO_IPV6 ||
+		ipproto == IPPROTO_IPIP ||
+#if IS_ENABLED(CONFIG_MPLS)
+		ipproto == IPPROTO_MPLS ||
+#endif
+		ipproto == 0;
+}
+
+static int
+ipip6_tunnel_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
+{
+	int err = 0;
+	struct ip_tunnel_parm p;
+	struct ip_tunnel_prl prl;
+	struct ip_tunnel *t = netdev_priv(dev);
+	struct net *net = t->net;
+	struct sit_net *sitn = net_generic(net, sit_net_id);
+#ifdef CONFIG_IPV6_SIT_6RD
+	struct ip_tunnel_6rd ip6rd;
+#endif
+
+	switch (cmd) {
+	case SIOCGETTUNNEL:
+#ifdef CONFIG_IPV6_SIT_6RD
+	case SIOCGET6RD:
+#endif
+		if (dev == sitn->fb_tunnel_dev) {
+			if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
+				err = -EFAULT;
+				break;
+			}
+			t = ipip6_tunnel_locate(net, &p, 0);
+			if (!t)
+				t = netdev_priv(dev);
+		}
+
+		err = -EFAULT;
+		if (cmd == SIOCGETTUNNEL) {
+			memcpy(&p, &t->parms, sizeof(p));
+			if (copy_to_user(ifr->ifr_ifru.ifru_data, &p,
+					 sizeof(p)))
+				goto done;
+#ifdef CONFIG_IPV6_SIT_6RD
+		} else {
+			ip6rd.prefix = t->ip6rd.prefix;
+			ip6rd.relay_prefix = t->ip6rd.relay_prefix;
+			ip6rd.prefixlen = t->ip6rd.prefixlen;
+			ip6rd.relay_prefixlen = t->ip6rd.relay_prefixlen;
+			if (copy_to_user(ifr->ifr_ifru.ifru_data, &ip6rd,
+					 sizeof(ip6rd)))
+				goto done;
+#endif
+		}
+		err = 0;
+		break;
+
+	case SIOCADDTUNNEL:
+	case SIOCCHGTUNNEL:
+		err = -EPERM;
+		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
+			goto done;
+
+		err = -EFAULT;
+		if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
+			goto done;
+
+		err = -EINVAL;
+		if (!ipip6_valid_ip_proto(p.iph.protocol))
+			goto done;
+		if (p.iph.version != 4 ||
+		    p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
+			goto done;
+		if (p.iph.ttl)
+			p.iph.frag_off |= htons(IP_DF);
+
+		t = ipip6_tunnel_locate(net, &p, cmd == SIOCADDTUNNEL);
+
+		if (dev != sitn->fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
+			if (t) {
+				if (t->dev != dev) {
+					err = -EEXIST;
+					break;
+				}
+			} else {
+				if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
+				    (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
+					err = -EINVAL;
+					break;
+				}
+				t = netdev_priv(dev);
+			}
+
+			ipip6_tunnel_update(t, &p, t->fwmark);
+		}
+
+		if (t) {
+			err = 0;
+			if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
+				err = -EFAULT;
+		} else
+			err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
+		break;
+
+	case SIOCDELTUNNEL:
+		err = -EPERM;
+		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
+			goto done;
+
+		if (dev == sitn->fb_tunnel_dev) {
+			err = -EFAULT;
+			if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
+				goto done;
+			err = -ENOENT;
+			t = ipip6_tunnel_locate(net, &p, 0);
+			if (!t)
+				goto done;
+			err = -EPERM;
+			if (t == netdev_priv(sitn->fb_tunnel_dev))
+				goto done;
+			dev = t->dev;
+		}
+		unregister_netdevice(dev);
+		err = 0;
+		break;
+
+	case SIOCGETPRL:
+		err = -EINVAL;
+		if (dev == sitn->fb_tunnel_dev)
+			goto done;
+		err = ipip6_tunnel_get_prl(t, ifr->ifr_ifru.ifru_data);
+		break;
+
+	case SIOCADDPRL:
+	case SIOCDELPRL:
+	case SIOCCHGPRL:
+		err = -EPERM;
+		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
+			goto done;
+		err = -EINVAL;
+		if (dev == sitn->fb_tunnel_dev)
+			goto done;
+		err = -EFAULT;
+		if (copy_from_user(&prl, ifr->ifr_ifru.ifru_data, sizeof(prl)))
+			goto done;
+
+		switch (cmd) {
+		case SIOCDELPRL:
+			err = ipip6_tunnel_del_prl(t, &prl);
+			break;
+		case SIOCADDPRL:
+		case SIOCCHGPRL:
+			err = ipip6_tunnel_add_prl(t, &prl, cmd == SIOCCHGPRL);
+			break;
+		}
+		dst_cache_reset(&t->dst_cache);
+		netdev_state_change(dev);
+		break;
+
+#ifdef CONFIG_IPV6_SIT_6RD
+	case SIOCADD6RD:
+	case SIOCCHG6RD:
+	case SIOCDEL6RD:
+		err = -EPERM;
+		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
+			goto done;
+
+		err = -EFAULT;
+		if (copy_from_user(&ip6rd, ifr->ifr_ifru.ifru_data,
+				   sizeof(ip6rd)))
+			goto done;
+
+		if (cmd != SIOCDEL6RD) {
+			err = ipip6_tunnel_update_6rd(t, &ip6rd);
+			if (err < 0)
+				goto done;
+		} else
+			ipip6_tunnel_clone_6rd(dev, sitn);
+
+		err = 0;
+		break;
+#endif
+
+	default:
+		err = -EINVAL;
+	}
+
+done:
+	return err;
+}
+
+static const struct net_device_ops ipip6_netdev_ops = {
+	.ndo_init	= ipip6_tunnel_init,
+	.ndo_uninit	= ipip6_tunnel_uninit,
+	.ndo_start_xmit	= sit_tunnel_xmit,
+	.ndo_do_ioctl	= ipip6_tunnel_ioctl,
+	.ndo_get_stats64 = ip_tunnel_get_stats64,
+	.ndo_get_iflink = ip_tunnel_get_iflink,
+};
+
+static void ipip6_dev_free(struct net_device *dev)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+
+	dst_cache_destroy(&tunnel->dst_cache);
+	free_percpu(dev->tstats);
+}
+
+#define SIT_FEATURES (NETIF_F_SG	   | \
+		      NETIF_F_FRAGLIST	   | \
+		      NETIF_F_HIGHDMA	   | \
+		      NETIF_F_GSO_SOFTWARE | \
+		      NETIF_F_HW_CSUM)
+
+static void ipip6_tunnel_setup(struct net_device *dev)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+	int t_hlen = tunnel->hlen + sizeof(struct iphdr);
+
+	dev->netdev_ops		= &ipip6_netdev_ops;
+	dev->needs_free_netdev	= true;
+	dev->priv_destructor	= ipip6_dev_free;
+
+	dev->type		= ARPHRD_SIT;
+	dev->mtu		= ETH_DATA_LEN - t_hlen;
+	dev->min_mtu		= IPV6_MIN_MTU;
+	dev->max_mtu		= IP6_MAX_MTU - t_hlen;
+	dev->flags		= IFF_NOARP;
+	netif_keep_dst(dev);
+	dev->addr_len		= 4;
+	dev->features		|= NETIF_F_LLTX;
+	dev->features		|= SIT_FEATURES;
+	dev->hw_features	|= SIT_FEATURES;
+}
+
+static int ipip6_tunnel_init(struct net_device *dev)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+	int err;
+
+	tunnel->dev = dev;
+	tunnel->net = dev_net(dev);
+	strcpy(tunnel->parms.name, dev->name);
+
+	ipip6_tunnel_bind_dev(dev);
+	dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
+	if (!dev->tstats)
+		return -ENOMEM;
+
+	err = dst_cache_init(&tunnel->dst_cache, GFP_KERNEL);
+	if (err) {
+		free_percpu(dev->tstats);
+		dev->tstats = NULL;
+		return err;
+	}
+	dev_hold(dev);
+	return 0;
+}
+
+static void __net_init ipip6_fb_tunnel_init(struct net_device *dev)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+	struct iphdr *iph = &tunnel->parms.iph;
+	struct net *net = dev_net(dev);
+	struct sit_net *sitn = net_generic(net, sit_net_id);
+
+	iph->version		= 4;
+	iph->protocol		= IPPROTO_IPV6;
+	iph->ihl		= 5;
+	iph->ttl		= 64;
+
+	rcu_assign_pointer(sitn->tunnels_wc[0], tunnel);
+}
+
+static int ipip6_validate(struct nlattr *tb[], struct nlattr *data[],
+			  struct netlink_ext_ack *extack)
+{
+	u8 proto;
+
+	if (!data || !data[IFLA_IPTUN_PROTO])
+		return 0;
+
+	proto = nla_get_u8(data[IFLA_IPTUN_PROTO]);
+	if (!ipip6_valid_ip_proto(proto))
+		return -EINVAL;
+
+	return 0;
+}
+
+static void ipip6_netlink_parms(struct nlattr *data[],
+				struct ip_tunnel_parm *parms,
+				__u32 *fwmark)
+{
+	memset(parms, 0, sizeof(*parms));
+
+	parms->iph.version = 4;
+	parms->iph.protocol = IPPROTO_IPV6;
+	parms->iph.ihl = 5;
+	parms->iph.ttl = 64;
+
+	if (!data)
+		return;
+
+	if (data[IFLA_IPTUN_LINK])
+		parms->link = nla_get_u32(data[IFLA_IPTUN_LINK]);
+
+	if (data[IFLA_IPTUN_LOCAL])
+		parms->iph.saddr = nla_get_be32(data[IFLA_IPTUN_LOCAL]);
+
+	if (data[IFLA_IPTUN_REMOTE])
+		parms->iph.daddr = nla_get_be32(data[IFLA_IPTUN_REMOTE]);
+
+	if (data[IFLA_IPTUN_TTL]) {
+		parms->iph.ttl = nla_get_u8(data[IFLA_IPTUN_TTL]);
+		if (parms->iph.ttl)
+			parms->iph.frag_off = htons(IP_DF);
+	}
+
+	if (data[IFLA_IPTUN_TOS])
+		parms->iph.tos = nla_get_u8(data[IFLA_IPTUN_TOS]);
+
+	if (!data[IFLA_IPTUN_PMTUDISC] || nla_get_u8(data[IFLA_IPTUN_PMTUDISC]))
+		parms->iph.frag_off = htons(IP_DF);
+
+	if (data[IFLA_IPTUN_FLAGS])
+		parms->i_flags = nla_get_be16(data[IFLA_IPTUN_FLAGS]);
+
+	if (data[IFLA_IPTUN_PROTO])
+		parms->iph.protocol = nla_get_u8(data[IFLA_IPTUN_PROTO]);
+
+	if (data[IFLA_IPTUN_FWMARK])
+		*fwmark = nla_get_u32(data[IFLA_IPTUN_FWMARK]);
+}
+
+/* This function returns true when ENCAP attributes are present in the nl msg */
+static bool ipip6_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_IPTUN_ENCAP_TYPE]) {
+		ret = true;
+		ipencap->type = nla_get_u16(data[IFLA_IPTUN_ENCAP_TYPE]);
+	}
+
+	if (data[IFLA_IPTUN_ENCAP_FLAGS]) {
+		ret = true;
+		ipencap->flags = nla_get_u16(data[IFLA_IPTUN_ENCAP_FLAGS]);
+	}
+
+	if (data[IFLA_IPTUN_ENCAP_SPORT]) {
+		ret = true;
+		ipencap->sport = nla_get_be16(data[IFLA_IPTUN_ENCAP_SPORT]);
+	}
+
+	if (data[IFLA_IPTUN_ENCAP_DPORT]) {
+		ret = true;
+		ipencap->dport = nla_get_be16(data[IFLA_IPTUN_ENCAP_DPORT]);
+	}
+
+	return ret;
+}
+
+#ifdef CONFIG_IPV6_SIT_6RD
+/* This function returns true when 6RD attributes are present in the nl msg */
+static bool ipip6_netlink_6rd_parms(struct nlattr *data[],
+				    struct ip_tunnel_6rd *ip6rd)
+{
+	bool ret = false;
+	memset(ip6rd, 0, sizeof(*ip6rd));
+
+	if (!data)
+		return ret;
+
+	if (data[IFLA_IPTUN_6RD_PREFIX]) {
+		ret = true;
+		ip6rd->prefix = nla_get_in6_addr(data[IFLA_IPTUN_6RD_PREFIX]);
+	}
+
+	if (data[IFLA_IPTUN_6RD_RELAY_PREFIX]) {
+		ret = true;
+		ip6rd->relay_prefix =
+			nla_get_be32(data[IFLA_IPTUN_6RD_RELAY_PREFIX]);
+	}
+
+	if (data[IFLA_IPTUN_6RD_PREFIXLEN]) {
+		ret = true;
+		ip6rd->prefixlen = nla_get_u16(data[IFLA_IPTUN_6RD_PREFIXLEN]);
+	}
+
+	if (data[IFLA_IPTUN_6RD_RELAY_PREFIXLEN]) {
+		ret = true;
+		ip6rd->relay_prefixlen =
+			nla_get_u16(data[IFLA_IPTUN_6RD_RELAY_PREFIXLEN]);
+	}
+
+	return ret;
+}
+#endif
+
+static int ipip6_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 ip_tunnel *nt;
+	struct ip_tunnel_encap ipencap;
+#ifdef CONFIG_IPV6_SIT_6RD
+	struct ip_tunnel_6rd ip6rd;
+#endif
+	int err;
+
+	nt = netdev_priv(dev);
+
+	if (ipip6_netlink_encap_parms(data, &ipencap)) {
+		err = ip_tunnel_encap_setup(nt, &ipencap);
+		if (err < 0)
+			return err;
+	}
+
+	ipip6_netlink_parms(data, &nt->parms, &nt->fwmark);
+
+	if (ipip6_tunnel_locate(net, &nt->parms, 0))
+		return -EEXIST;
+
+	err = ipip6_tunnel_create(dev);
+	if (err < 0)
+		return err;
+
+	if (tb[IFLA_MTU]) {
+		u32 mtu = nla_get_u32(tb[IFLA_MTU]);
+
+		if (mtu >= IPV6_MIN_MTU &&
+		    mtu <= IP6_MAX_MTU - dev->hard_header_len)
+			dev->mtu = mtu;
+	}
+
+#ifdef CONFIG_IPV6_SIT_6RD
+	if (ipip6_netlink_6rd_parms(data, &ip6rd)) {
+		err = ipip6_tunnel_update_6rd(nt, &ip6rd);
+		if (err < 0)
+			unregister_netdevice_queue(dev, NULL);
+	}
+#endif
+
+	return err;
+}
+
+static int ipip6_changelink(struct net_device *dev, struct nlattr *tb[],
+			    struct nlattr *data[],
+			    struct netlink_ext_ack *extack)
+{
+	struct ip_tunnel *t = netdev_priv(dev);
+	struct ip_tunnel_parm p;
+	struct ip_tunnel_encap ipencap;
+	struct net *net = t->net;
+	struct sit_net *sitn = net_generic(net, sit_net_id);
+#ifdef CONFIG_IPV6_SIT_6RD
+	struct ip_tunnel_6rd ip6rd;
+#endif
+	__u32 fwmark = t->fwmark;
+	int err;
+
+	if (dev == sitn->fb_tunnel_dev)
+		return -EINVAL;
+
+	if (ipip6_netlink_encap_parms(data, &ipencap)) {
+		err = ip_tunnel_encap_setup(t, &ipencap);
+		if (err < 0)
+			return err;
+	}
+
+	ipip6_netlink_parms(data, &p, &fwmark);
+
+	if (((dev->flags & IFF_POINTOPOINT) && !p.iph.daddr) ||
+	    (!(dev->flags & IFF_POINTOPOINT) && p.iph.daddr))
+		return -EINVAL;
+
+	t = ipip6_tunnel_locate(net, &p, 0);
+
+	if (t) {
+		if (t->dev != dev)
+			return -EEXIST;
+	} else
+		t = netdev_priv(dev);
+
+	ipip6_tunnel_update(t, &p, fwmark);
+
+#ifdef CONFIG_IPV6_SIT_6RD
+	if (ipip6_netlink_6rd_parms(data, &ip6rd))
+		return ipip6_tunnel_update_6rd(t, &ip6rd);
+#endif
+
+	return 0;
+}
+
+static size_t ipip6_get_size(const struct net_device *dev)
+{
+	return
+		/* IFLA_IPTUN_LINK */
+		nla_total_size(4) +
+		/* IFLA_IPTUN_LOCAL */
+		nla_total_size(4) +
+		/* IFLA_IPTUN_REMOTE */
+		nla_total_size(4) +
+		/* IFLA_IPTUN_TTL */
+		nla_total_size(1) +
+		/* IFLA_IPTUN_TOS */
+		nla_total_size(1) +
+		/* IFLA_IPTUN_PMTUDISC */
+		nla_total_size(1) +
+		/* IFLA_IPTUN_FLAGS */
+		nla_total_size(2) +
+		/* IFLA_IPTUN_PROTO */
+		nla_total_size(1) +
+#ifdef CONFIG_IPV6_SIT_6RD
+		/* IFLA_IPTUN_6RD_PREFIX */
+		nla_total_size(sizeof(struct in6_addr)) +
+		/* IFLA_IPTUN_6RD_RELAY_PREFIX */
+		nla_total_size(4) +
+		/* IFLA_IPTUN_6RD_PREFIXLEN */
+		nla_total_size(2) +
+		/* IFLA_IPTUN_6RD_RELAY_PREFIXLEN */
+		nla_total_size(2) +
+#endif
+		/* IFLA_IPTUN_ENCAP_TYPE */
+		nla_total_size(2) +
+		/* IFLA_IPTUN_ENCAP_FLAGS */
+		nla_total_size(2) +
+		/* IFLA_IPTUN_ENCAP_SPORT */
+		nla_total_size(2) +
+		/* IFLA_IPTUN_ENCAP_DPORT */
+		nla_total_size(2) +
+		/* IFLA_IPTUN_FWMARK */
+		nla_total_size(4) +
+		0;
+}
+
+static int ipip6_fill_info(struct sk_buff *skb, const struct net_device *dev)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+	struct ip_tunnel_parm *parm = &tunnel->parms;
+
+	if (nla_put_u32(skb, IFLA_IPTUN_LINK, parm->link) ||
+	    nla_put_in_addr(skb, IFLA_IPTUN_LOCAL, parm->iph.saddr) ||
+	    nla_put_in_addr(skb, IFLA_IPTUN_REMOTE, parm->iph.daddr) ||
+	    nla_put_u8(skb, IFLA_IPTUN_TTL, parm->iph.ttl) ||
+	    nla_put_u8(skb, IFLA_IPTUN_TOS, parm->iph.tos) ||
+	    nla_put_u8(skb, IFLA_IPTUN_PMTUDISC,
+		       !!(parm->iph.frag_off & htons(IP_DF))) ||
+	    nla_put_u8(skb, IFLA_IPTUN_PROTO, parm->iph.protocol) ||
+	    nla_put_be16(skb, IFLA_IPTUN_FLAGS, parm->i_flags) ||
+	    nla_put_u32(skb, IFLA_IPTUN_FWMARK, tunnel->fwmark))
+		goto nla_put_failure;
+
+#ifdef CONFIG_IPV6_SIT_6RD
+	if (nla_put_in6_addr(skb, IFLA_IPTUN_6RD_PREFIX,
+			     &tunnel->ip6rd.prefix) ||
+	    nla_put_in_addr(skb, IFLA_IPTUN_6RD_RELAY_PREFIX,
+			    tunnel->ip6rd.relay_prefix) ||
+	    nla_put_u16(skb, IFLA_IPTUN_6RD_PREFIXLEN,
+			tunnel->ip6rd.prefixlen) ||
+	    nla_put_u16(skb, IFLA_IPTUN_6RD_RELAY_PREFIXLEN,
+			tunnel->ip6rd.relay_prefixlen))
+		goto nla_put_failure;
+#endif
+
+	if (nla_put_u16(skb, IFLA_IPTUN_ENCAP_TYPE,
+			tunnel->encap.type) ||
+	    nla_put_be16(skb, IFLA_IPTUN_ENCAP_SPORT,
+			tunnel->encap.sport) ||
+	    nla_put_be16(skb, IFLA_IPTUN_ENCAP_DPORT,
+			tunnel->encap.dport) ||
+	    nla_put_u16(skb, IFLA_IPTUN_ENCAP_FLAGS,
+			tunnel->encap.flags))
+		goto nla_put_failure;
+
+	return 0;
+
+nla_put_failure:
+	return -EMSGSIZE;
+}
+
+static const struct nla_policy ipip6_policy[IFLA_IPTUN_MAX + 1] = {
+	[IFLA_IPTUN_LINK]		= { .type = NLA_U32 },
+	[IFLA_IPTUN_LOCAL]		= { .type = NLA_U32 },
+	[IFLA_IPTUN_REMOTE]		= { .type = NLA_U32 },
+	[IFLA_IPTUN_TTL]		= { .type = NLA_U8 },
+	[IFLA_IPTUN_TOS]		= { .type = NLA_U8 },
+	[IFLA_IPTUN_PMTUDISC]		= { .type = NLA_U8 },
+	[IFLA_IPTUN_FLAGS]		= { .type = NLA_U16 },
+	[IFLA_IPTUN_PROTO]		= { .type = NLA_U8 },
+#ifdef CONFIG_IPV6_SIT_6RD
+	[IFLA_IPTUN_6RD_PREFIX]		= { .len = sizeof(struct in6_addr) },
+	[IFLA_IPTUN_6RD_RELAY_PREFIX]	= { .type = NLA_U32 },
+	[IFLA_IPTUN_6RD_PREFIXLEN]	= { .type = NLA_U16 },
+	[IFLA_IPTUN_6RD_RELAY_PREFIXLEN] = { .type = NLA_U16 },
+#endif
+	[IFLA_IPTUN_ENCAP_TYPE]		= { .type = NLA_U16 },
+	[IFLA_IPTUN_ENCAP_FLAGS]	= { .type = NLA_U16 },
+	[IFLA_IPTUN_ENCAP_SPORT]	= { .type = NLA_U16 },
+	[IFLA_IPTUN_ENCAP_DPORT]	= { .type = NLA_U16 },
+	[IFLA_IPTUN_FWMARK]		= { .type = NLA_U32 },
+};
+
+static void ipip6_dellink(struct net_device *dev, struct list_head *head)
+{
+	struct net *net = dev_net(dev);
+	struct sit_net *sitn = net_generic(net, sit_net_id);
+
+	if (dev != sitn->fb_tunnel_dev)
+		unregister_netdevice_queue(dev, head);
+}
+
+static struct rtnl_link_ops sit_link_ops __read_mostly = {
+	.kind		= "sit",
+	.maxtype	= IFLA_IPTUN_MAX,
+	.policy		= ipip6_policy,
+	.priv_size	= sizeof(struct ip_tunnel),
+	.setup		= ipip6_tunnel_setup,
+	.validate	= ipip6_validate,
+	.newlink	= ipip6_newlink,
+	.changelink	= ipip6_changelink,
+	.get_size	= ipip6_get_size,
+	.fill_info	= ipip6_fill_info,
+	.dellink	= ipip6_dellink,
+	.get_link_net	= ip_tunnel_get_link_net,
+};
+
+static struct xfrm_tunnel sit_handler __read_mostly = {
+	.handler	=	ipip6_rcv,
+	.err_handler	=	ipip6_err,
+	.priority	=	1,
+};
+
+static struct xfrm_tunnel ipip_handler __read_mostly = {
+	.handler	=	ipip_rcv,
+	.err_handler	=	ipip6_err,
+	.priority	=	2,
+};
+
+#if IS_ENABLED(CONFIG_MPLS)
+static struct xfrm_tunnel mplsip_handler __read_mostly = {
+	.handler	=	mplsip_rcv,
+	.err_handler	=	ipip6_err,
+	.priority	=	2,
+};
+#endif
+
+static void __net_exit sit_destroy_tunnels(struct net *net,
+					   struct list_head *head)
+{
+	struct sit_net *sitn = net_generic(net, sit_net_id);
+	struct net_device *dev, *aux;
+	int prio;
+
+	for_each_netdev_safe(net, dev, aux)
+		if (dev->rtnl_link_ops == &sit_link_ops)
+			unregister_netdevice_queue(dev, head);
+
+	for (prio = 0; prio < 4; prio++) {
+		int h;
+		for (h = 0; h < (prio ? IP6_SIT_HASH_SIZE : 1); h++) {
+			struct ip_tunnel *t;
+
+			t = rtnl_dereference(sitn->tunnels[prio][h]);
+			while (t) {
+				/* If dev is in the same netns, it has already
+				 * been added to the list by the previous loop.
+				 */
+				if (!net_eq(dev_net(t->dev), net))
+					unregister_netdevice_queue(t->dev,
+								   head);
+				t = rtnl_dereference(t->next);
+			}
+		}
+	}
+}
+
+static int __net_init sit_init_net(struct net *net)
+{
+	struct sit_net *sitn = net_generic(net, sit_net_id);
+	struct ip_tunnel *t;
+	int err;
+
+	sitn->tunnels[0] = sitn->tunnels_wc;
+	sitn->tunnels[1] = sitn->tunnels_l;
+	sitn->tunnels[2] = sitn->tunnels_r;
+	sitn->tunnels[3] = sitn->tunnels_r_l;
+
+	if (!net_has_fallback_tunnels(net))
+		return 0;
+
+	sitn->fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0",
+					   NET_NAME_UNKNOWN,
+					   ipip6_tunnel_setup);
+	if (!sitn->fb_tunnel_dev) {
+		err = -ENOMEM;
+		goto err_alloc_dev;
+	}
+	dev_net_set(sitn->fb_tunnel_dev, net);
+	sitn->fb_tunnel_dev->rtnl_link_ops = &sit_link_ops;
+	/* FB netdevice is special: we have one, and only one per netns.
+	 * Allowing to move it to another netns is clearly unsafe.
+	 */
+	sitn->fb_tunnel_dev->features |= NETIF_F_NETNS_LOCAL;
+
+	err = register_netdev(sitn->fb_tunnel_dev);
+	if (err)
+		goto err_reg_dev;
+
+	ipip6_tunnel_clone_6rd(sitn->fb_tunnel_dev, sitn);
+	ipip6_fb_tunnel_init(sitn->fb_tunnel_dev);
+
+	t = netdev_priv(sitn->fb_tunnel_dev);
+
+	strcpy(t->parms.name, sitn->fb_tunnel_dev->name);
+	return 0;
+
+err_reg_dev:
+	free_netdev(sitn->fb_tunnel_dev);
+err_alloc_dev:
+	return err;
+}
+
+static void __net_exit sit_exit_batch_net(struct list_head *net_list)
+{
+	LIST_HEAD(list);
+	struct net *net;
+
+	rtnl_lock();
+	list_for_each_entry(net, net_list, exit_list)
+		sit_destroy_tunnels(net, &list);
+
+	unregister_netdevice_many(&list);
+	rtnl_unlock();
+}
+
+static struct pernet_operations sit_net_ops = {
+	.init = sit_init_net,
+	.exit_batch = sit_exit_batch_net,
+	.id   = &sit_net_id,
+	.size = sizeof(struct sit_net),
+};
+
+static void __exit sit_cleanup(void)
+{
+	rtnl_link_unregister(&sit_link_ops);
+	xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
+	xfrm4_tunnel_deregister(&ipip_handler, AF_INET);
+#if IS_ENABLED(CONFIG_MPLS)
+	xfrm4_tunnel_deregister(&mplsip_handler, AF_MPLS);
+#endif
+
+	unregister_pernet_device(&sit_net_ops);
+	rcu_barrier(); /* Wait for completion of call_rcu()'s */
+}
+
+static int __init sit_init(void)
+{
+	int err;
+
+	pr_info("IPv6, IPv4 and MPLS over IPv4 tunneling driver\n");
+
+	err = register_pernet_device(&sit_net_ops);
+	if (err < 0)
+		return err;
+	err = xfrm4_tunnel_register(&sit_handler, AF_INET6);
+	if (err < 0) {
+		pr_info("%s: can't register ip6ip4\n", __func__);
+		goto xfrm_tunnel_failed;
+	}
+	err = xfrm4_tunnel_register(&ipip_handler, AF_INET);
+	if (err < 0) {
+		pr_info("%s: can't register ip4ip4\n", __func__);
+		goto xfrm_tunnel4_failed;
+	}
+#if IS_ENABLED(CONFIG_MPLS)
+	err = xfrm4_tunnel_register(&mplsip_handler, AF_MPLS);
+	if (err < 0) {
+		pr_info("%s: can't register mplsip\n", __func__);
+		goto xfrm_tunnel_mpls_failed;
+	}
+#endif
+	err = rtnl_link_register(&sit_link_ops);
+	if (err < 0)
+		goto rtnl_link_failed;
+
+out:
+	return err;
+
+rtnl_link_failed:
+#if IS_ENABLED(CONFIG_MPLS)
+	xfrm4_tunnel_deregister(&mplsip_handler, AF_MPLS);
+xfrm_tunnel_mpls_failed:
+#endif
+	xfrm4_tunnel_deregister(&ipip_handler, AF_INET);
+xfrm_tunnel4_failed:
+	xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
+xfrm_tunnel_failed:
+	unregister_pernet_device(&sit_net_ops);
+	goto out;
+}
+
+module_init(sit_init);
+module_exit(sit_cleanup);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_RTNL_LINK("sit");
+MODULE_ALIAS_NETDEV("sit0");