/* * 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> * * $Id: sit.c,v 1.53 2001/09/25 05:09:53 davem Exp $ * * 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 */ #include <linux/config.h> #include <linux/module.h> #include <linux/errno.h> #include <linux/types.h> #include <linux/socket.h> #include <linux/sockios.h> #include <linux/sched.h> #include <linux/net.h> #include <linux/in6.h> #include <linux/netdevice.h> #include <linux/if_arp.h> #include <linux/icmp.h> #include <asm/uaccess.h> #include <linux/init.h> #include <linux/netfilter_ipv4.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/ipip.h> #include <net/inet_ecn.h> #include <net/xfrm.h> #include <net/dsfield.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 HASH_SIZE 16 #define HASH(addr) ((addr^(addr>>4))&0xF) static int ipip6_fb_tunnel_init(struct net_device *dev); static int ipip6_tunnel_init(struct net_device *dev); static void ipip6_tunnel_setup(struct net_device *dev); static struct net_device *ipip6_fb_tunnel_dev; static struct ip_tunnel *tunnels_r_l[HASH_SIZE]; static struct ip_tunnel *tunnels_r[HASH_SIZE]; static struct ip_tunnel *tunnels_l[HASH_SIZE]; static struct ip_tunnel *tunnels_wc[1]; static struct ip_tunnel **tunnels[4] = { tunnels_wc, tunnels_l, tunnels_r, tunnels_r_l }; static DEFINE_RWLOCK(ipip6_lock); static struct ip_tunnel * ipip6_tunnel_lookup(u32 remote, u32 local) { unsigned h0 = HASH(remote); unsigned h1 = HASH(local); struct ip_tunnel *t; for (t = tunnels_r_l[h0^h1]; t; t = t->next) { if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP)) return t; } for (t = tunnels_r[h0]; t; t = t->next) { if (remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP)) return t; } for (t = tunnels_l[h1]; t; t = t->next) { if (local == t->parms.iph.saddr && (t->dev->flags&IFF_UP)) return t; } if ((t = tunnels_wc[0]) != NULL && (t->dev->flags&IFF_UP)) return t; return NULL; } static struct ip_tunnel ** ipip6_bucket(struct ip_tunnel *t) { u32 remote = t->parms.iph.daddr; u32 local = t->parms.iph.saddr; unsigned h = 0; int prio = 0; if (remote) { prio |= 2; h ^= HASH(remote); } if (local) { prio |= 1; h ^= HASH(local); } return &tunnels[prio][h]; } static void ipip6_tunnel_unlink(struct ip_tunnel *t) { struct ip_tunnel **tp; for (tp = ipip6_bucket(t); *tp; tp = &(*tp)->next) { if (t == *tp) { write_lock_bh(&ipip6_lock); *tp = t->next; write_unlock_bh(&ipip6_lock); break; } } } static void ipip6_tunnel_link(struct ip_tunnel *t) { struct ip_tunnel **tp = ipip6_bucket(t); t->next = *tp; write_lock_bh(&ipip6_lock); *tp = t; write_unlock_bh(&ipip6_lock); } static struct ip_tunnel * ipip6_tunnel_locate(struct ip_tunnel_parm *parms, int create) { u32 remote = parms->iph.daddr; u32 local = parms->iph.saddr; struct ip_tunnel *t, **tp, *nt; struct net_device *dev; unsigned h = 0; int prio = 0; char name[IFNAMSIZ]; if (remote) { prio |= 2; h ^= HASH(remote); } if (local) { prio |= 1; h ^= HASH(local); } for (tp = &tunnels[prio][h]; (t = *tp) != NULL; tp = &t->next) { if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr) return t; } if (!create) goto failed; if (parms->name[0]) strlcpy(name, parms->name, IFNAMSIZ); else { int i; for (i=1; i<100; i++) { sprintf(name, "sit%d", i); if (__dev_get_by_name(name) == NULL) break; } if (i==100) goto failed; } dev = alloc_netdev(sizeof(*t), name, ipip6_tunnel_setup); if (dev == NULL) return NULL; nt = dev->priv; dev->init = ipip6_tunnel_init; nt->parms = *parms; if (register_netdevice(dev) < 0) { free_netdev(dev); goto failed; } dev_hold(dev); ipip6_tunnel_link(nt); /* Do not decrement MOD_USE_COUNT here. */ return nt; failed: return NULL; } static void ipip6_tunnel_uninit(struct net_device *dev) { if (dev == ipip6_fb_tunnel_dev) { write_lock_bh(&ipip6_lock); tunnels_wc[0] = NULL; write_unlock_bh(&ipip6_lock); dev_put(dev); } else { ipip6_tunnel_unlink((struct ip_tunnel*)dev->priv); dev_put(dev); } } static void ipip6_err(struct sk_buff *skb, u32 info) { #ifndef I_WISH_WORLD_WERE_PERFECT /* It is not :-( 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; int type = skb->h.icmph->type; int code = skb->h.icmph->code; struct ip_tunnel *t; switch (type) { default: case ICMP_PARAMETERPROB: return; case ICMP_DEST_UNREACH: switch (code) { case ICMP_SR_FAILED: case ICMP_PORT_UNREACH: /* Impossible event. */ return; case ICMP_FRAG_NEEDED: /* Soft state for pmtu is maintained by IP core. */ return; 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; break; } read_lock(&ipip6_lock); t = ipip6_tunnel_lookup(iph->daddr, iph->saddr); if (t == NULL || t->parms.iph.daddr == 0) goto out; if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED) goto out; if (jiffies - t->err_time < IPTUNNEL_ERR_TIMEO) t->err_count++; else t->err_count = 1; t->err_time = jiffies; out: read_unlock(&ipip6_lock); return; #else struct iphdr *iph = (struct iphdr*)dp; int hlen = iph->ihl<<2; struct ipv6hdr *iph6; int type = skb->h.icmph->type; int code = skb->h.icmph->code; int rel_type = 0; int rel_code = 0; int rel_info = 0; struct sk_buff *skb2; struct rt6_info *rt6i; if (len < hlen + sizeof(struct ipv6hdr)) return; iph6 = (struct ipv6hdr*)(dp + hlen); switch (type) { default: return; case ICMP_PARAMETERPROB: if (skb->h.icmph->un.gateway < hlen) return; /* So... This guy found something strange INSIDE encapsulated packet. Well, he is fool, but what can we do ? */ rel_type = ICMPV6_PARAMPROB; rel_info = skb->h.icmph->un.gateway - hlen; break; case ICMP_DEST_UNREACH: switch (code) { case ICMP_SR_FAILED: case ICMP_PORT_UNREACH: /* Impossible event. */ return; case ICMP_FRAG_NEEDED: /* Too complicated case ... */ return; default: /* All others are translated to HOST_UNREACH. rfc2003 contains "deep thoughts" about NET_UNREACH, I believe, it is just ether pollution. --ANK */ rel_type = ICMPV6_DEST_UNREACH; rel_code = ICMPV6_ADDR_UNREACH; break; } break; case ICMP_TIME_EXCEEDED: if (code != ICMP_EXC_TTL) return; rel_type = ICMPV6_TIME_EXCEED; rel_code = ICMPV6_EXC_HOPLIMIT; break; } /* Prepare fake skb to feed it to icmpv6_send */ skb2 = skb_clone(skb, GFP_ATOMIC); if (skb2 == NULL) return; dst_release(skb2->dst); skb2->dst = NULL; skb_pull(skb2, skb->data - (u8*)iph6); skb2->nh.raw = skb2->data; /* Try to guess incoming interface */ rt6i = rt6_lookup(&iph6->saddr, NULL, NULL, 0); if (rt6i && rt6i->rt6i_dev) { skb2->dev = rt6i->rt6i_dev; rt6i = rt6_lookup(&iph6->daddr, &iph6->saddr, NULL, 0); if (rt6i && rt6i->rt6i_dev && rt6i->rt6i_dev->type == ARPHRD_SIT) { struct ip_tunnel * t = (struct ip_tunnel*)rt6i->rt6i_dev->priv; if (rel_type == ICMPV6_TIME_EXCEED && t->parms.iph.ttl) { rel_type = ICMPV6_DEST_UNREACH; rel_code = ICMPV6_ADDR_UNREACH; } icmpv6_send(skb2, rel_type, rel_code, rel_info, skb2->dev); } } kfree_skb(skb2); return; #endif } static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb) { if (INET_ECN_is_ce(iph->tos)) IP6_ECN_set_ce(skb->nh.ipv6h); } static int ipip6_rcv(struct sk_buff *skb) { struct iphdr *iph; struct ip_tunnel *tunnel; if (!pskb_may_pull(skb, sizeof(struct ipv6hdr))) goto out; iph = skb->nh.iph; read_lock(&ipip6_lock); if ((tunnel = ipip6_tunnel_lookup(iph->saddr, iph->daddr)) != NULL) { secpath_reset(skb); skb->mac.raw = skb->nh.raw; skb->nh.raw = skb->data; memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options)); skb->protocol = htons(ETH_P_IPV6); skb->pkt_type = PACKET_HOST; tunnel->stat.rx_packets++; tunnel->stat.rx_bytes += skb->len; skb->dev = tunnel->dev; dst_release(skb->dst); skb->dst = NULL; nf_reset(skb); ipip6_ecn_decapsulate(iph, skb); netif_rx(skb); read_unlock(&ipip6_lock); return 0; } icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PROT_UNREACH, 0); kfree_skb(skb); read_unlock(&ipip6_lock); out: return 0; } /* Returns the embedded IPv4 address if the IPv6 address comes from 6to4 (RFC 3056) addr space */ static inline u32 try_6to4(struct in6_addr *v6dst) { u32 dst = 0; if (v6dst->s6_addr16[0] == htons(0x2002)) { /* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */ memcpy(&dst, &v6dst->s6_addr16[1], 4); } return dst; } /* * This function assumes it is being called from dev_queue_xmit() * and that skb is filled properly by that function. */ static int ipip6_tunnel_xmit(struct sk_buff *skb, struct net_device *dev) { struct ip_tunnel *tunnel = (struct ip_tunnel*)dev->priv; struct net_device_stats *stats = &tunnel->stat; struct iphdr *tiph = &tunnel->parms.iph; struct ipv6hdr *iph6 = skb->nh.ipv6h; u8 tos = tunnel->parms.iph.tos; struct rtable *rt; /* Route to the other host */ struct net_device *tdev; /* Device to other host */ struct iphdr *iph; /* Our new IP header */ int max_headroom; /* The extra header space needed */ u32 dst = tiph->daddr; int mtu; struct in6_addr *addr6; int addr_type; if (tunnel->recursion++) { tunnel->stat.collisions++; goto tx_error; } if (skb->protocol != htons(ETH_P_IPV6)) goto tx_error; if (!dst) dst = try_6to4(&iph6->daddr); if (!dst) { struct neighbour *neigh = NULL; if (skb->dst) neigh = skb->dst->neighbour; if (neigh == NULL) { if (net_ratelimit()) printk(KERN_DEBUG "sit: nexthop == NULL\n"); goto tx_error; } addr6 = (struct in6_addr*)&neigh->primary_key; addr_type = ipv6_addr_type(addr6); if (addr_type == IPV6_ADDR_ANY) { addr6 = &skb->nh.ipv6h->daddr; addr_type = ipv6_addr_type(addr6); } if ((addr_type & IPV6_ADDR_COMPATv4) == 0) goto tx_error_icmp; dst = addr6->s6_addr32[3]; } { struct flowi fl = { .nl_u = { .ip4_u = { .daddr = dst, .saddr = tiph->saddr, .tos = RT_TOS(tos) } }, .oif = tunnel->parms.link, .proto = IPPROTO_IPV6 }; if (ip_route_output_key(&rt, &fl)) { tunnel->stat.tx_carrier_errors++; goto tx_error_icmp; } } if (rt->rt_type != RTN_UNICAST) { ip_rt_put(rt); tunnel->stat.tx_carrier_errors++; goto tx_error_icmp; } tdev = rt->u.dst.dev; if (tdev == dev) { ip_rt_put(rt); tunnel->stat.collisions++; goto tx_error; } if (tiph->frag_off) mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr); else mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu; if (mtu < 68) { tunnel->stat.collisions++; ip_rt_put(rt); goto tx_error; } if (mtu < IPV6_MIN_MTU) mtu = IPV6_MIN_MTU; if (tunnel->parms.iph.daddr && skb->dst) skb->dst->ops->update_pmtu(skb->dst, mtu); if (skb->len > mtu) { icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev); ip_rt_put(rt); goto tx_error; } if (tunnel->err_count > 0) { if (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)+sizeof(struct iphdr); if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) { struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom); if (!new_skb) { ip_rt_put(rt); stats->tx_dropped++; dev_kfree_skb(skb); tunnel->recursion--; return 0; } if (skb->sk) skb_set_owner_w(new_skb, skb->sk); dev_kfree_skb(skb); skb = new_skb; iph6 = skb->nh.ipv6h; } skb->h.raw = skb->nh.raw; skb->nh.raw = skb_push(skb, sizeof(struct iphdr)); memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); dst_release(skb->dst); skb->dst = &rt->u.dst; /* * Push down and install the IPIP header. */ iph = skb->nh.iph; iph->version = 4; iph->ihl = sizeof(struct iphdr)>>2; if (mtu > IPV6_MIN_MTU) iph->frag_off = htons(IP_DF); else iph->frag_off = 0; iph->protocol = IPPROTO_IPV6; iph->tos = INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6)); iph->daddr = rt->rt_dst; iph->saddr = rt->rt_src; if ((iph->ttl = tiph->ttl) == 0) iph->ttl = iph6->hop_limit; nf_reset(skb); IPTUNNEL_XMIT(); tunnel->recursion--; return 0; tx_error_icmp: dst_link_failure(skb); tx_error: stats->tx_errors++; dev_kfree_skb(skb); tunnel->recursion--; return 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 *t; switch (cmd) { case SIOCGETTUNNEL: t = NULL; if (dev == ipip6_fb_tunnel_dev) { if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) { err = -EFAULT; break; } t = ipip6_tunnel_locate(&p, 0); } if (t == NULL) t = (struct ip_tunnel*)dev->priv; memcpy(&p, &t->parms, sizeof(p)); 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_IPV6 || 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(&p, cmd == SIOCADDTUNNEL); if (dev != ipip6_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 = (struct ip_tunnel*)dev->priv; ipip6_tunnel_unlink(t); t->parms.iph.saddr = p.iph.saddr; t->parms.iph.daddr = p.iph.daddr; memcpy(dev->dev_addr, &p.iph.saddr, 4); memcpy(dev->broadcast, &p.iph.daddr, 4); ipip6_tunnel_link(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; } 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 == ipip6_fb_tunnel_dev) { err = -EFAULT; if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) goto done; err = -ENOENT; if ((t = ipip6_tunnel_locate(&p, 0)) == NULL) goto done; err = -EPERM; if (t == ipip6_fb_tunnel_dev->priv) goto done; dev = t->dev; } err = unregister_netdevice(dev); break; default: err = -EINVAL; } done: return err; } static struct net_device_stats *ipip6_tunnel_get_stats(struct net_device *dev) { return &(((struct ip_tunnel*)dev->priv)->stat); } static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu) { if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - sizeof(struct iphdr)) return -EINVAL; dev->mtu = new_mtu; return 0; } static void ipip6_tunnel_setup(struct net_device *dev) { SET_MODULE_OWNER(dev); dev->uninit = ipip6_tunnel_uninit; dev->destructor = free_netdev; dev->hard_start_xmit = ipip6_tunnel_xmit; dev->get_stats = ipip6_tunnel_get_stats; dev->do_ioctl = ipip6_tunnel_ioctl; dev->change_mtu = ipip6_tunnel_change_mtu; dev->type = ARPHRD_SIT; dev->hard_header_len = LL_MAX_HEADER + sizeof(struct iphdr); dev->mtu = 1500 - sizeof(struct iphdr); dev->flags = IFF_NOARP; dev->iflink = 0; dev->addr_len = 4; } static int ipip6_tunnel_init(struct net_device *dev) { struct net_device *tdev = NULL; struct ip_tunnel *tunnel; struct iphdr *iph; tunnel = (struct ip_tunnel*)dev->priv; iph = &tunnel->parms.iph; 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); if (iph->daddr) { struct flowi fl = { .nl_u = { .ip4_u = { .daddr = iph->daddr, .saddr = iph->saddr, .tos = RT_TOS(iph->tos) } }, .oif = tunnel->parms.link, .proto = IPPROTO_IPV6 }; struct rtable *rt; if (!ip_route_output_key(&rt, &fl)) { tdev = rt->u.dst.dev; ip_rt_put(rt); } dev->flags |= IFF_POINTOPOINT; } if (!tdev && tunnel->parms.link) tdev = __dev_get_by_index(tunnel->parms.link); if (tdev) { dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr); dev->mtu = tdev->mtu - sizeof(struct iphdr); if (dev->mtu < IPV6_MIN_MTU) dev->mtu = IPV6_MIN_MTU; } dev->iflink = tunnel->parms.link; return 0; } int __init ipip6_fb_tunnel_init(struct net_device *dev) { struct ip_tunnel *tunnel = dev->priv; struct iphdr *iph = &tunnel->parms.iph; tunnel->dev = dev; strcpy(tunnel->parms.name, dev->name); iph->version = 4; iph->protocol = IPPROTO_IPV6; iph->ihl = 5; iph->ttl = 64; dev_hold(dev); tunnels_wc[0] = tunnel; return 0; } static struct net_protocol sit_protocol = { .handler = ipip6_rcv, .err_handler = ipip6_err, }; void __exit sit_cleanup(void) { inet_del_protocol(&sit_protocol, IPPROTO_IPV6); unregister_netdev(ipip6_fb_tunnel_dev); } int __init sit_init(void) { int err; printk(KERN_INFO "IPv6 over IPv4 tunneling driver\n"); if (inet_add_protocol(&sit_protocol, IPPROTO_IPV6) < 0) { printk(KERN_INFO "sit init: Can't add protocol\n"); return -EAGAIN; } ipip6_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0", ipip6_tunnel_setup); if (!ipip6_fb_tunnel_dev) { err = -ENOMEM; goto err1; } ipip6_fb_tunnel_dev->init = ipip6_fb_tunnel_init; if ((err = register_netdev(ipip6_fb_tunnel_dev))) goto err2; out: return err; err2: free_netdev(ipip6_fb_tunnel_dev); err1: inet_del_protocol(&sit_protocol, IPPROTO_IPV6); goto out; }