Subject: Re: [net-next PATCH 02/02] net/ipv4: VTI support new module for ip_vti.

From: Steffen Klassert <[email-masked]>
Date: Thu, 14 Jun 2012 11:12:54 +0200

On Fri, Jun 08, 2012 at 10:32:53AM -0700, Saurabh wrote:
> 
> 
> New VTI tunnel kernel module, Kconfig and Makefile changes.

It is an interesting feature, do you plan for an IPv6
version too?

I made some comments on the code below.

Thanks.

> 
> Signed-off-by: Saurabh Mohan <[email-masked]>
> Reviewed-by: Stephen Hemminger <[email-masked]>
> 
> ---
> diff --git a/include/linux/if_tunnel.h b/include/linux/if_tunnel.h
> index 16b92d0..4b4ce17 100644
> --- a/include/linux/if_tunnel.h
> +++ b/include/linux/if_tunnel.h
> @@ -80,4 +80,15 @@ enum {
>  
>  #define IFLA_GRE_MAX	(__IFLA_GRE_MAX - 1)
>  
> +enum {
> +	IFLA_VTI_UNSPEC,
> +	IFLA_VTI_LINK,
> +	IFLA_VTI_IKEY,
> +	IFLA_VTI_OKEY,
> +	IFLA_VTI_LOCAL,
> +	IFLA_VTI_REMOTE,
> +	__IFLA_VTI_MAX,
> +};
> +
> +#define IFLA_VTI_MAX	(__IFLA_VTI_MAX - 1)
>  #endif /* _IF_TUNNEL_H_ */
> diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
> index 20f1cb5..3a95308 100644
> --- a/net/ipv4/Kconfig
> +++ b/net/ipv4/Kconfig
> @@ -310,6 +310,20 @@ config SYN_COOKIES
>  
>  	  If unsure, say N.
>  
> +config NET_IPVTI
> +    tristate "Virtual (secure) IP: tunneling"
> +    select INET_TUNNEL

You added your register/deregister functions to net/ipv4/xfrm4_mode_tunnel.c,
so this should somehow select or depend on INET_XFRM_MODE_TUNNEL.

> +    ---help---
> +      Tunneling means encapsulating data of one protocol type within
> +      another protocol and sending it over a channel that understands the
> +      Pencapsulating protocol. This particular tunneling driver implements
> +      encapsulation of IP within IP-ESP. This can be used with xfrm to give
> +      the notion of a secure tunnel and then use routing protocol on top.
> +
> +      Saying Y to this option will produce one module ( = code which can
> +      be inserted in and removed from the running kernel whenever you
> +      want). Most people won't need this and can say N.
> +
>  config INET_AH
>  	tristate "IP: AH transformation"
>  	select XFRM_ALGO
> diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
> index ff75d3b..3999ce9 100644
> --- a/net/ipv4/Makefile
> +++ b/net/ipv4/Makefile
> @@ -20,6 +20,7 @@ obj-$(CONFIG_IP_MROUTE) += ipmr.o
>  obj-$(CONFIG_NET_IPIP) += ipip.o
>  obj-$(CONFIG_NET_IPGRE_DEMUX) += gre.o
>  obj-$(CONFIG_NET_IPGRE) += ip_gre.o
> +obj-$(CONFIG_NET_IPVTI) += ip_vti.o
>  obj-$(CONFIG_SYN_COOKIES) += syncookies.o
>  obj-$(CONFIG_INET_AH) += ah4.o
>  obj-$(CONFIG_INET_ESP) += esp4.o
> diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c
> new file mode 100644
> index 0000000..3eaa47c
> --- /dev/null
> +++ b/net/ipv4/ip_vti.c
> @@ -0,0 +1,980 @@
> +/*
> + *	Linux NET3:	IP/IP protocol decoder modified to support virtual tunnel interface
> + *
> + *	Authors:
> + *		Sam Lantinga ([email-masked])  02/01/95
> + *		Saurabh Mohan ([email-masked]) 05/07/2012
> + *
> + *	This program is free software; you can redistribute it and/or
> + *	modify it under the terms of the GNU General Public License
> + *	as published by the Free Software Foundation; either version
> + *	2 of the License, or (at your option) any later version.
> + *
> + */
> +
> +/*
> +   This version of net/ipv4/ip_vti.c is cloned of net/ipv4/ipip.c
> +
> +   For comments look at net/ipv4/ip_gre.c --ANK
> + */
> +
> +
> +#include <linux/capability.h>
> +#include <linux/module.h>
> +#include <linux/types.h>
> +#include <linux/kernel.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/mroute.h>
> +#include <linux/init.h>
> +#include <linux/netfilter_ipv4.h>
> +#include <linux/if_ether.h>
> +
> +#include <net/sock.h>
> +#include <net/ip.h>
> +#include <net/icmp.h>
> +#include <net/ipip.h>
> +#include <net/inet_ecn.h>
> +#include <net/xfrm.h>
> +#include <net/net_namespace.h>
> +#include <net/netns/generic.h>
> +
> +#define HASH_SIZE  16
> +#define HASH(addr) (((__force u32)addr^((__force u32)addr>>4))&0xF)
> +
> +static struct rtnl_link_ops vti_link_ops __read_mostly;
> +
> +static int vti_net_id __read_mostly;
> +struct vti_net {
> +	struct ip_tunnel __rcu *tunnels_r_l[HASH_SIZE];
> +	struct ip_tunnel __rcu *tunnels_r[HASH_SIZE];
> +	struct ip_tunnel __rcu *tunnels_l[HASH_SIZE];
> +	struct ip_tunnel __rcu *tunnels_wc[1];
> +	struct ip_tunnel **tunnels[4];
> +
> +	struct net_device *fb_tunnel_dev;
> +};
> +
> +static int vti_fb_tunnel_init(struct net_device *dev);
> +static int vti_tunnel_init(struct net_device *dev);
> +static void vti_tunnel_setup(struct net_device *dev);
> +static void vti_dev_free(struct net_device *dev);
> +static int vti_tunnel_bind_dev(struct net_device *dev);
> +
> +/*
> + * Locking : hash tables are protected by RCU and RTNL
> + */
> +
> +#define for_each_ip_tunnel_rcu(start) \
> +	for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))
> +
> +/* often modified stats are per cpu, other are shared (netdev->stats) */
> +struct pcpu_tstats {
> +	u64	rx_packets;
> +	u64	rx_bytes;
> +	u64	tx_packets;
> +	u64	tx_bytes;
> +	struct	u64_stats_sync	syncp;
> +};
> +
> +#define VTI_XMIT(stats1, stats2) do {				\
> +	int err;						\
> +	int pkt_len = skb->len;					\
> +	err = dst_output(skb);					\
> +	if (net_xmit_eval(err) == 0) {				\
> +		(stats1)->tx_bytes += pkt_len;			\
> +		(stats1)->tx_packets++;				\
> +	} else {						\
> +		(stats2)->tx_errors++;				\
> +		(stats2)->tx_aborted_errors++;			\
> +	}							\
> +} while (0)
> +
> +
> +static struct rtnl_link_stats64 *vti_get_stats64(struct net_device *dev,
> +					       struct rtnl_link_stats64 *tot)
> +{
> +	int i;
> +
> +	for_each_possible_cpu(i) {
> +		const struct pcpu_tstats *tstats = per_cpu_ptr(dev->tstats, i);
> +		u64 rx_packets, rx_bytes, tx_packets, tx_bytes;
> +		unsigned int start;
> +
> +		do {
> +			start = u64_stats_fetch_begin_bh(&tstats->syncp);
> +			rx_packets = tstats->rx_packets;
> +			tx_packets = tstats->tx_packets;
> +			rx_bytes = tstats->rx_bytes;
> +			tx_bytes = tstats->tx_bytes;
> +		} while (u64_stats_fetch_retry_bh(&tstats->syncp, start));
> +
> +		tot->rx_packets += rx_packets;
> +		tot->tx_packets += tx_packets;
> +		tot->rx_bytes   += rx_bytes;
> +		tot->tx_bytes   += tx_bytes;
> +	}
> +
> +	tot->multicast = dev->stats.multicast;
> +	tot->rx_crc_errors = dev->stats.rx_crc_errors;
> +	tot->rx_fifo_errors = dev->stats.rx_fifo_errors;
> +	tot->rx_length_errors = dev->stats.rx_length_errors;
> +	tot->rx_errors = dev->stats.rx_errors;
> +	tot->tx_fifo_errors = dev->stats.tx_fifo_errors;
> +	tot->tx_carrier_errors = dev->stats.tx_carrier_errors;
> +	tot->tx_dropped = dev->stats.tx_dropped;
> +	tot->tx_aborted_errors = dev->stats.tx_aborted_errors;
> +	tot->tx_errors = dev->stats.tx_errors;
> +
> +	return tot;
> +}
> +
> +static struct ip_tunnel *vti_tunnel_lookup(struct net *net,
> +					 __be32 remote, __be32 local)
> +{
> +	unsigned h0 = HASH(remote);
> +	unsigned h1 = HASH(local);
> +	struct ip_tunnel *t;
> +	struct vti_net *ipn = net_generic(net, vti_net_id);
> +
> +	for_each_ip_tunnel_rcu(ipn->tunnels_r_l[h0 ^ h1])
> +		if (local == t->parms.iph.saddr &&
> +		    remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
> +			return t;
> +	for_each_ip_tunnel_rcu(ipn->tunnels_r[h0])
> +		if (remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
> +			return t;
> +
> +	for_each_ip_tunnel_rcu(ipn->tunnels_l[h1])
> +		if (local == t->parms.iph.saddr && (t->dev->flags&IFF_UP))
> +			return t;
> +
> +	for_each_ip_tunnel_rcu(ipn->tunnels_wc[0])
> +		if (t && (t->dev->flags&IFF_UP))
> +			return t;
> +	return NULL;
> +}
> +
> +static struct ip_tunnel **__vti_bucket(struct vti_net *ipn,
> +				     struct ip_tunnel_parm *parms)
> +{
> +	__be32 remote = parms->iph.daddr;
> +	__be32 local = parms->iph.saddr;
> +	unsigned h = 0;
> +	int prio = 0;
> +
> +	if (remote) {
> +		prio |= 2;
> +		h ^= HASH(remote);
> +	}
> +	if (local) {
> +		prio |= 1;
> +		h ^= HASH(local);
> +	}
> +	return &ipn->tunnels[prio][h];
> +}
> +
> +static inline struct ip_tunnel **vti_bucket(struct vti_net *ipn,
> +					  struct ip_tunnel *t)
> +{
> +	return __vti_bucket(ipn, &t->parms);
> +}
> +
> +static void vti_tunnel_unlink(struct vti_net *ipn, struct ip_tunnel *t)
> +{
> +	struct ip_tunnel __rcu **tp;
> +	struct ip_tunnel *iter;
> +
> +	for (tp = vti_bucket(ipn, t);
> +	     (iter = rtnl_dereference(*tp)) != NULL;
> +	     tp = &iter->next) {
> +		if (t == iter) {
> +			rcu_assign_pointer(*tp, t->next);
> +			break;
> +		}
> +	}
> +}
> +
> +static void vti_tunnel_link(struct vti_net *ipn, struct ip_tunnel *t)
> +{
> +	struct ip_tunnel __rcu **tp = vti_bucket(ipn, t);
> +
> +	rcu_assign_pointer(t->next, rtnl_dereference(*tp));
> +	rcu_assign_pointer(*tp, t);
> +}
> +
> +static struct ip_tunnel *vti_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 vti_net *ipn = net_generic(net, vti_net_id);
> +
> +	for (tp = __vti_bucket(ipn, parms);
> +	     (t = rtnl_dereference(*tp)) != NULL;
> +	     tp = &t->next) {
> +		if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr)
> +			return t;
> +	}
> +	if (!create)
> +		return NULL;
> +
> +	if (parms->name[0])
> +		strlcpy(name, parms->name, IFNAMSIZ);
> +	else
> +		strcpy(name, "vti%d");
> +
> +	dev = alloc_netdev(sizeof(*t), name, vti_tunnel_setup);
> +	if (dev == NULL)
> +		return NULL;
> +
> +	dev_net_set(dev, net);
> +
> +	nt = netdev_priv(dev);
> +	nt->parms = *parms;
> +	dev->rtnl_link_ops = &vti_link_ops;
> +
> +	vti_tunnel_bind_dev(dev);
> +
> +	if (register_netdevice(dev) < 0)
> +		goto failed_free;
> +
> +	dev_hold(dev);
> +	vti_tunnel_link(ipn, nt);
> +	return nt;
> +
> + failed_free:
> +	free_netdev(dev);
> +	return NULL;
> +}
> +
> +static void vti_tunnel_uninit(struct net_device *dev)
> +{
> +	struct net *net = dev_net(dev);
> +	struct vti_net *ipn = net_generic(net, vti_net_id);
> +
> +	if (dev == ipn->fb_tunnel_dev)
> +		RCU_INIT_POINTER(ipn->tunnels_wc[0], NULL);
> +	else
> +		vti_tunnel_unlink(ipn, netdev_priv(dev));
> +	dev_put(dev);
> +}
> +
> +static int vti_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.
> +	 */
> +	struct iphdr *iph = (struct iphdr *)skb->data;
> +	const int type = icmp_hdr(skb)->type;
> +	const int code = icmp_hdr(skb)->code;
> +	struct ip_tunnel *t;
> +	int err;
> +
> +	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;
> +		case ICMP_FRAG_NEEDED:
> +			/* Soft state for pmtu is maintained by IP core. */
> +			return 0;
> +		default:
> +			/* All others are translated to HOST_UNREACH. */
> +			break;
> +		}
> +		break;
> +	case ICMP_TIME_EXCEEDED:
> +		if (code != ICMP_EXC_TTL)
> +			return 0;
> +		break;
> +	}
> +
> +	err = -ENOENT;
> +
> +	rcu_read_lock();
> +	t = vti_tunnel_lookup(dev_net(skb->dev), iph->daddr, iph->saddr);
> +	if (t == NULL || t->parms.iph.daddr == 0)
> +		goto out;
> +
> +	err = 0;
> +	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:
> +	rcu_read_unlock();
> +	return err;
> +}
> +
> +static inline void vti_ecn_decapsulate(const struct iphdr *outer_iph,
> +					struct sk_buff *skb)
> +{
> +	struct iphdr *inner_iph = ip_hdr(skb);
> +
> +	if (INET_ECN_is_ce(outer_iph->tos))
> +		IP_ECN_set_ce(inner_iph);
> +}

vti_ecn_decapsulate is unused.

> +
> +/*
> + * We dont digest the packet therefore let the packet pass.
> + */
> +static int vti_rcv(struct sk_buff *skb)
> +{
> +	struct ip_tunnel *tunnel;
> +	const struct iphdr *iph = ip_hdr(skb);
> +
> +	rcu_read_lock();
> +	tunnel = vti_tunnel_lookup(dev_net(skb->dev), iph->saddr, iph->daddr);
> +	if (tunnel != NULL) {
> +		struct pcpu_tstats *tstats;
> +
> +		tstats = this_cpu_ptr(tunnel->dev->tstats);
> +		tstats->rx_packets++;
> +		tstats->rx_bytes += skb->len;
> +
> +		skb->dev = tunnel->dev;
> +		skb_dst_drop(skb);

Really need to drop a refcount here? xfrm_input() does that too before
it reinjects the packet into layer 2.

> +		nf_reset(skb);

Same here.

> +		rcu_read_unlock();
> +		/* We do not eat the packet here therefore return 1 */
> +		return 1;
> +	}
> +	rcu_read_unlock();
> +
> +	return -1;
> +}
> +
> +/*
> + *	This function assumes it is being called from dev_queue_xmit()
> + *	and that skb is filled properly by that function.
> + */
> +
> +static netdev_tx_t vti_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
> +{
> +	struct ip_tunnel *tunnel = netdev_priv(dev);
> +	struct pcpu_tstats *tstats;
> +	struct net_device_stats *stats = &tunnel->dev->stats;
> +	struct iphdr  *tiph = &tunnel->parms.iph;
> +	u8     tos = tunnel->parms.iph.tos;
> +	struct rtable *rt;		/* Route to the other host */
> +	struct net_device *tdev;	/* Device to other host */
> +	struct iphdr  *old_iph = ip_hdr(skb);
> +	__be32 dst = tiph->daddr;
> +	struct flowi4 fl4;
> +
> +	if (skb->protocol != htons(ETH_P_IP))
> +		goto tx_error;
> +
> +	if (tos&1)
> +		tos = old_iph->tos;
> +
> +	if (!dst) {
> +		/* NBMA tunnel */
> +		rt = skb_rtable(skb);
> +		if (rt == NULL) {
> +			stats->tx_fifo_errors++;
> +			goto tx_error;
> +		}
> +		dst = rt->rt_gateway;
> +		if (dst == 0)
> +			goto tx_error_icmp;
> +	}
> +
> +	memset(&fl4, 0, sizeof(fl4));
> +	flowi4_init_output(&fl4, tunnel->parms.link,
> +		htonl(tunnel->parms.i_key), RT_TOS(tos), RT_SCOPE_UNIVERSE,
> +		IPPROTO_IPIP, 0,
> +		dst, tiph->saddr, 0, 0);
> +	rt = ip_route_output_key(dev_net(dev), &fl4);
> +	if (IS_ERR(rt)) {
> +		dev->stats.tx_carrier_errors++;
> +		goto tx_error_icmp;
> +	}
> +#ifdef CONFIG_XFRM
> +		/* if there is no transform then this tunnel is not functional. */
> +		if (!rt->dst.xfrm) {
> +			stats->tx_carrier_errors++;
> +			goto tx_error_icmp;
> +		}
> +#endif
> +	tdev = rt->dst.dev;
> +
> +	if (tdev == dev) {
> +		ip_rt_put(rt);
> +		stats->collisions++;
> +		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;
> +	}
> +
> +
> +	IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
> +			      IPSKB_REROUTED);
> +	skb_dst_drop(skb);
> +	skb_dst_set(skb, &rt->dst);
> +	nf_reset(skb);
> +	skb->dev = skb_dst(skb)->dev;
> +
> +	tstats = this_cpu_ptr(dev->tstats);
> +	VTI_XMIT(tstats, &dev->stats);
> +	return NETDEV_TX_OK;
> +
> +tx_error_icmp:
> +	dst_link_failure(skb);
> +tx_error:
> +	stats->tx_errors++;
> +	dev_kfree_skb(skb);
> +	return NETDEV_TX_OK;
> +}
> +
> +static int vti_tunnel_bind_dev(struct net_device *dev)
> +{
> +	struct net_device *tdev = NULL;
> +	struct ip_tunnel *tunnel;
> +	struct iphdr *iph;
> +
> +	tunnel = netdev_priv(dev);
> +	iph = &tunnel->parms.iph;
> +
> +	if (iph->daddr) {
> +		struct rtable *rt;
> +		struct flowi4 fl4;
> +		memset(&fl4, 0, sizeof(fl4));
> +		flowi4_init_output(&fl4, tunnel->parms.link,
> +				htonl(tunnel->parms.i_key), RT_TOS(iph->tos), RT_SCOPE_UNIVERSE,
> +				IPPROTO_IPIP, 0,
> +				iph->daddr, iph->saddr, 0, 0);
> +		rt = ip_route_output_key(dev_net(dev), &fl4);
> +		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(dev_net(dev), tunnel->parms.link);
> +
> +	if (tdev) {
> +		dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
> +		dev->mtu = tdev->mtu;
> +	}
> +	dev->iflink = tunnel->parms.link;
> +	return dev->mtu;
> +}
> +
> +static int
> +vti_tunnel_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
> +{
> +	int err = 0;
> +	struct ip_tunnel_parm p;
> +	struct ip_tunnel *t;
> +	struct net *net = dev_net(dev);
> +	struct vti_net *ipn = net_generic(net, vti_net_id);
> +
> +	switch (cmd) {
> +	case SIOCGETTUNNEL:
> +		t = NULL;
> +		if (dev == ipn->fb_tunnel_dev) {
> +			if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
> +				err = -EFAULT;
> +				break;
> +			}
> +			t = vti_tunnel_locate(net, &p, 0);
> +		}
> +		if (t == NULL)
> +			t = netdev_priv(dev);
> +		memcpy(&p, &t->parms, sizeof(p));
> +		p.i_flags |= GRE_KEY;
> +		p.o_flags |= GRE_KEY;
> +		if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
> +			err = -EFAULT;
> +		break;
> +
> +	case SIOCADDTUNNEL:
> +	case SIOCCHGTUNNEL:
> +		err = -EPERM;
> +		if (!capable(CAP_NET_ADMIN))
> +			goto done;
> +
> +		err = -EFAULT;
> +		if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
> +			goto done;
> +
> +		err = -EINVAL;
> +		if (p.iph.version != 4 || p.iph.protocol != IPPROTO_ESP ||
> +		    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 = vti_tunnel_locate(net, &p, cmd == SIOCADDTUNNEL);
> +
> +		if (dev != ipn->fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
> +			if (t != NULL) {
> +				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);
> +				vti_tunnel_unlink(ipn, t);
> +				synchronize_net();
> +				t->parms.iph.saddr = p.iph.saddr;
> +				t->parms.iph.daddr = p.iph.daddr;
> +				t->parms.i_key = p.i_key;
> +				t->parms.o_key = p.o_key;
> +				t->parms.iph.protocol = IPPROTO_ESP;
> +				memcpy(dev->dev_addr, &p.iph.saddr, 4);
> +				memcpy(dev->broadcast, &p.iph.daddr, 4);
> +				vti_tunnel_link(ipn, t);
> +				netdev_state_change(dev);
> +			}
> +		}
> +
> +		if (t) {
> +			err = 0;
> +			if (cmd == SIOCCHGTUNNEL) {
> +				t->parms.iph.ttl = p.iph.ttl;
> +				t->parms.iph.tos = p.iph.tos;
> +				t->parms.iph.frag_off = p.iph.frag_off;
> +				t->parms.i_key = p.i_key;
> +				t->parms.o_key = p.o_key;
> +				if (t->parms.link != p.link) {
> +					t->parms.link = p.link;
> +					vti_tunnel_bind_dev(dev);
> +					netdev_state_change(dev);
> +				}
> +			}
> +			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 (!capable(CAP_NET_ADMIN))
> +			goto done;
> +
> +		if (dev == ipn->fb_tunnel_dev) {
> +			err = -EFAULT;
> +			if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
> +				goto done;
> +			err = -ENOENT;
> +
> +			t = vti_tunnel_locate(net, &p, 0);
> +			if (t == NULL)
> +				goto done;
> +			err = -EPERM;
> +			if (t->dev == ipn->fb_tunnel_dev)
> +				goto done;
> +			dev = t->dev;
> +		}
> +		unregister_netdevice(dev);
> +		err = 0;
> +		break;
> +
> +	default:
> +		err = -EINVAL;
> +	}
> +
> +done:
> +	return err;
> +}
> +
> +static int vti_tunnel_change_mtu(struct net_device *dev, int new_mtu)
> +{
> +	if (new_mtu < 68 || new_mtu > 0xFFF8)
> +		return -EINVAL;
> +	dev->mtu = new_mtu;
> +	return 0;
> +}
> +
> +static const struct net_device_ops vti_netdev_ops = {
> +	.ndo_init	= vti_tunnel_init,
> +	.ndo_uninit	= vti_tunnel_uninit,
> +	.ndo_start_xmit	= vti_tunnel_xmit,
> +	.ndo_do_ioctl	= vti_tunnel_ioctl,
> +	.ndo_change_mtu	= vti_tunnel_change_mtu,
> +	.ndo_get_stats64  = vti_get_stats64,
> +};
> +
> +static void vti_dev_free(struct net_device *dev)
> +{
> +	free_percpu(dev->tstats);
> +	free_netdev(dev);
> +}
> +
> +static void vti_tunnel_setup(struct net_device *dev)
> +{
> +	dev->netdev_ops		= &vti_netdev_ops;
> +	dev->destructor		= vti_dev_free;
> +
> +	dev->type		= ARPHRD_TUNNEL;
> +	dev->hard_header_len	= LL_MAX_HEADER + sizeof(struct iphdr);
> +	dev->mtu		= ETH_DATA_LEN;
> +	dev->flags		= IFF_NOARP;
> +	dev->iflink		= 0;
> +	dev->addr_len		= 4;
> +	dev->features		|= NETIF_F_NETNS_LOCAL;
> +	dev->features		|= NETIF_F_LLTX;
> +	dev->priv_flags		&= ~IFF_XMIT_DST_RELEASE;
> +}
> +
> +static int vti_tunnel_init(struct net_device *dev)
> +{
> +	struct ip_tunnel *tunnel = netdev_priv(dev);
> +
> +	tunnel->dev = dev;
> +	strcpy(tunnel->parms.name, dev->name);
> +
> +	memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
> +	memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
> +
> +	dev->tstats = alloc_percpu(struct pcpu_tstats);
> +	if (!dev->tstats)
> +		return -ENOMEM;
> +
> +	return 0;
> +}
> +
> +static int __net_init vti_fb_tunnel_init(struct net_device *dev)
> +{
> +	struct ip_tunnel *tunnel = netdev_priv(dev);
> +	struct iphdr *iph = &tunnel->parms.iph;
> +	struct vti_net *ipn = net_generic(dev_net(dev), vti_net_id);
> +
> +	tunnel->dev = dev;
> +	strcpy(tunnel->parms.name, dev->name);
> +
> +	iph->version		= 4;
> +	iph->protocol		= IPPROTO_ESP;

Why IPPROTO_ESP? What's with the other IPsec protocols?
Shouldn't this be IPPROTO_IPIP?

> +	iph->ihl		= 5;
> +
> +	dev->tstats = alloc_percpu(struct pcpu_tstats);
> +	if (!dev->tstats)
> +		return -ENOMEM;
> +
> +	dev_hold(dev);
> +	rcu_assign_pointer(ipn->tunnels_wc[0], tunnel);
> +	return 0;
> +}
> +
> +static struct xfrm_tunnel vti_handler __read_mostly = {
> +	.handler	=	vti_rcv,
> +	.err_handler	=	vti_err,
> +	.priority	=	1,
> +};
> +
> +static void vti_destroy_tunnels(struct vti_net *ipn, struct list_head *head)
> +{
> +	int prio;
> +
> +	for (prio = 1; prio < 4; prio++) {
> +		int h;
> +		for (h = 0; h < HASH_SIZE; h++) {
> +			struct ip_tunnel *t;
> +
> +			t = rtnl_dereference(ipn->tunnels[prio][h]);
> +			while (t != NULL) {
> +				unregister_netdevice_queue(t->dev, head);
> +				t = rtnl_dereference(t->next);
> +			}
> +		}
> +	}
> +}
> +
> +static int __net_init vti_init_net(struct net *net)
> +{
> +	int err;
> +	struct vti_net *ipn = net_generic(net, vti_net_id);
> +
> +	ipn->tunnels[0] = ipn->tunnels_wc;
> +	ipn->tunnels[1] = ipn->tunnels_l;
> +	ipn->tunnels[2] = ipn->tunnels_r;
> +	ipn->tunnels[3] = ipn->tunnels_r_l;
> +
> +	ipn->fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel),
> +					   "ip_vti0",
> +					   vti_tunnel_setup);
> +	if (!ipn->fb_tunnel_dev) {
> +		err = -ENOMEM;
> +		goto err_alloc_dev;
> +	}
> +	dev_net_set(ipn->fb_tunnel_dev, net);
> +
> +	err = vti_fb_tunnel_init(ipn->fb_tunnel_dev);
> +	if (err)
> +		goto err_reg_dev;
> +	ipn->fb_tunnel_dev->rtnl_link_ops = &vti_link_ops;
> +
> +	err = register_netdev(ipn->fb_tunnel_dev);
> +	if (err)
> +		goto err_reg_dev;
> +	return 0;
> +
> +err_reg_dev:
> +	vti_dev_free(ipn->fb_tunnel_dev);
> +err_alloc_dev:
> +	/* nothing */
> +	return err;
> +}
> +
> +static void __net_exit vti_exit_net(struct net *net)
> +{
> +	struct vti_net *ipn = net_generic(net, vti_net_id);
> +	LIST_HEAD(list);
> +
> +	rtnl_lock();
> +	vti_destroy_tunnels(ipn, &list);
> +	unregister_netdevice_many(&list);
> +	rtnl_unlock();
> +}
> +
> +static struct pernet_operations vti_net_ops = {
> +	.init = vti_init_net,
> +	.exit = vti_exit_net,
> +	.id   = &vti_net_id,
> +	.size = sizeof(struct vti_net),
> +};
> +
> +static int vti_tunnel_validate(struct nlattr *tb[], struct nlattr *data[])
> +{
> +	return 0;
> +}
> +
> +static void vti_netlink_parms(struct nlattr *data[],
> +				struct ip_tunnel_parm *parms)
> +{
> +	memset(parms, 0, sizeof(*parms));
> +
> +	parms->iph.protocol = IPPROTO_ESP;
> +
> +	if (!data)
> +		return;
> +
> +	if (data[IFLA_VTI_LINK])
> +		parms->link = nla_get_u32(data[IFLA_VTI_LINK]);
> +
> +	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_LOCAL])
> +		parms->iph.saddr = nla_get_be32(data[IFLA_VTI_LOCAL]);
> +
> +	if (data[IFLA_VTI_REMOTE])
> +		parms->iph.daddr = nla_get_be32(data[IFLA_VTI_REMOTE]);
> +
> +}
> +
> +static int vti_newlink(struct net *src_net, struct net_device *dev, struct nlattr *tb[],
> +			 struct nlattr *data[])
> +{
> +	struct ip_tunnel *nt;
> +	struct net *net = dev_net(dev);
> +	struct vti_net *ipn = net_generic(net, vti_net_id);
> +	int mtu;
> +	int err;
> +
> +	nt = netdev_priv(dev);
> +	vti_netlink_parms(data, &nt->parms);
> +
> +	if (vti_tunnel_locate(net, &nt->parms, 0))
> +		return -EEXIST;
> +
> +	mtu = vti_tunnel_bind_dev(dev);
> +	if (!tb[IFLA_MTU])
> +		dev->mtu = mtu;
> +
> +	err = register_netdevice(dev);
> +	if (err)
> +		goto out;
> +
> +	dev_hold(dev);
> +	vti_tunnel_link(ipn, nt);
> +
> +out:
> +	return err;
> +	return 0;
> +}
> +
> +static int vti_changelink(struct net_device *dev, struct nlattr *tb[],
> +			    struct nlattr *data[])
> +{
> +	struct ip_tunnel *t, *nt;
> +	struct net *net = dev_net(dev);
> +	struct vti_net *ipn = net_generic(net, vti_net_id);
> +	struct ip_tunnel_parm p;
> +	int mtu;
> +
> +	if (dev == ipn->fb_tunnel_dev)
> +		return -EINVAL;
> +
> +	nt = netdev_priv(dev);
> +	vti_netlink_parms(data, &p);
> +
> +	t = vti_tunnel_locate(net, &p, 0);
> +
> +	if (t) {
> +		if (t->dev != dev)
> +			return -EEXIST;
> +	} else {
> +		t = nt;
> +
> +		vti_tunnel_unlink(ipn, t);
> +		t->parms.iph.saddr = p.iph.saddr;
> +		t->parms.iph.daddr = p.iph.daddr;
> +		t->parms.i_key = p.i_key;
> +		t->parms.o_key = p.o_key;
> +		if (dev->type != ARPHRD_ETHER) {
> +			memcpy(dev->dev_addr, &p.iph.saddr, 4);
> +			memcpy(dev->broadcast, &p.iph.daddr, 4);
> +		}
> +		vti_tunnel_link(ipn, t);
> +		netdev_state_change(dev);
> +	}
> +
> +	if (t->parms.link != p.link) {
> +		t->parms.link = p.link;
> +		mtu = vti_tunnel_bind_dev(dev);
> +		if (!tb[IFLA_MTU])
> +			dev->mtu = mtu;
> +		netdev_state_change(dev);
> +	}
> +
> +	return 0;
> +}
> +
> +static size_t vti_get_size(const struct net_device *dev)
> +{
> +	return
> +		/* IFLA_VTI_LINK */
> +		nla_total_size(4) +
> +		/* IFLA_VTI_IKEY */
> +		nla_total_size(4) +
> +		/* IFLA_VTI_OKEY */
> +		nla_total_size(4) +
> +		/* IFLA_VTI_LOCAL */
> +		nla_total_size(4) +
> +		/* IFLA_VTI_REMOTE */
> +		nla_total_size(4) +
> +		0;
> +}
> +
> +static int vti_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;
> +
> +	nla_put_u32(skb, IFLA_VTI_LINK, p->link);
> +	nla_put_be32(skb, IFLA_VTI_IKEY, p->i_key);
> +	nla_put_be32(skb, IFLA_VTI_OKEY, p->o_key);
> +	nla_put_be32(skb, IFLA_VTI_LOCAL, p->iph.saddr);
> +	nla_put_be32(skb, IFLA_VTI_REMOTE, p->iph.daddr);
> +
> +	return 0;
> +}
> +
> +static const struct nla_policy vti_policy[IFLA_VTI_MAX + 1] = {
> +	[IFLA_VTI_LINK]		= { .type = NLA_U32 },
> +	[IFLA_VTI_IKEY]		= { .type = NLA_U32 },
> +	[IFLA_VTI_OKEY]		= { .type = NLA_U32 },
> +	[IFLA_VTI_LOCAL]	= { .len = FIELD_SIZEOF(struct iphdr, saddr) },
> +	[IFLA_VTI_REMOTE]	= { .len = FIELD_SIZEOF(struct iphdr, daddr) },
> +};
> +
> +static struct rtnl_link_ops vti_link_ops __read_mostly = {
> +	.kind		= "vti",
> +	.maxtype	= IFLA_VTI_MAX,
> +	.policy		= vti_policy,
> +	.priv_size	= sizeof(struct ip_tunnel),
> +	.setup		= vti_tunnel_setup,
> +	.validate	= vti_tunnel_validate,
> +	.newlink	= vti_newlink,
> +	.changelink	= vti_changelink,
> +	.get_size	= vti_get_size,
> +	.fill_info	= vti_fill_info,
> +};
> +
> +static int __init vti_init(void)
> +{
> +	int err;
> +
> +	pr_info("IPv4 over ESP tunneling driver v4\n");
> +
> +	err = register_pernet_device(&vti_net_ops);
> +	if (err < 0)
> +		return err;
> +	err = xfrm4_mode_tunnel_input_register(&vti_handler);
> +	if (err < 0) {
> +		unregister_pernet_device(&vti_net_ops);
> +		pr_info(KERN_INFO "vti init: can't register tunnel\n");
> +	}
> +
> +	err = rtnl_link_register(&vti_link_ops);
> +	if (err < 0)
> +		goto rtnl_link_failed;
> +
> +	return err;
> +
> +rtnl_link_failed:
> +	xfrm4_mode_tunnel_input_deregister(&vti_handler);
> +	unregister_pernet_device(&vti_net_ops);
> +	return err;
> +}
> +
> +static void __exit vti_fini(void)
> +{
> +	rtnl_link_unregister(&vti_link_ops);
> +	if (xfrm4_mode_tunnel_input_deregister(&vti_handler))
> +		pr_info("vti close: can't deregister tunnel\n");
> +
> +	unregister_pernet_device(&vti_net_ops);
> +}
> +
> +module_init(vti_init);
> +module_exit(vti_fini);
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS_RTNL_LINK("vti");
> +MODULE_ALIAS_NETDEV("ip_vti0");
> --
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