diff options
Diffstat (limited to 'net/ipv4/ip_gre.c')
| -rw-r--r-- | net/ipv4/ip_gre.c | 1290 |
1 files changed, 1290 insertions, 0 deletions
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c new file mode 100644 index 00000000000..88483552222 --- /dev/null +++ b/net/ipv4/ip_gre.c @@ -0,0 +1,1290 @@ +/* + * Linux NET3: GRE over IP protocol decoder. + * + * Authors: 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. + * + */ + +#include <linux/config.h> +#include <linux/module.h> +#include <linux/types.h> +#include <linux/sched.h> +#include <linux/kernel.h> +#include <asm/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/in6.h> +#include <linux/inetdevice.h> +#include <linux/igmp.h> +#include <linux/netfilter_ipv4.h> + +#include <net/sock.h> +#include <net/ip.h> +#include <net/icmp.h> +#include <net/protocol.h> +#include <net/ipip.h> +#include <net/arp.h> +#include <net/checksum.h> +#include <net/dsfield.h> +#include <net/inet_ecn.h> +#include <net/xfrm.h> + +#ifdef CONFIG_IPV6 +#include <net/ipv6.h> +#include <net/ip6_fib.h> +#include <net/ip6_route.h> +#endif + +/* + Problems & solutions + -------------------- + + 1. The most important issue is detecting local dead loops. + They would cause complete host lockup in transmit, which + would be "resolved" by stack overflow or, if queueing is enabled, + with infinite looping in net_bh. + + We cannot track such dead loops during route installation, + it is infeasible task. The most general solutions would be + to keep skb->encapsulation counter (sort of local ttl), + and silently drop packet when it expires. It is the best + solution, but it supposes maintaing new variable in ALL + skb, even if no tunneling is used. + + Current solution: t->recursion lock breaks dead loops. It looks + like dev->tbusy flag, but I preferred new variable, because + the semantics is different. One day, when hard_start_xmit + will be multithreaded we will have to use skb->encapsulation. + + + + 2. Networking dead loops would not kill routers, but would really + kill network. IP hop limit plays role of "t->recursion" in this case, + if we copy it from packet being encapsulated to upper header. + It is very good solution, but it introduces two problems: + + - Routing protocols, using packets with ttl=1 (OSPF, RIP2), + do not work over tunnels. + - traceroute does not work. I planned to relay ICMP from tunnel, + so that this problem would be solved and traceroute output + would even more informative. This idea appeared to be wrong: + only Linux complies to rfc1812 now (yes, guys, Linux is the only + true router now :-)), all routers (at least, in neighbourhood of mine) + return only 8 bytes of payload. It is the end. + + Hence, if we want that OSPF worked or traceroute said something reasonable, + we should search for another solution. + + One of them is to parse packet trying to detect inner encapsulation + made by our node. It is difficult or even impossible, especially, + taking into account fragmentation. TO be short, tt is not solution at all. + + Current solution: The solution was UNEXPECTEDLY SIMPLE. + We force DF flag on tunnels with preconfigured hop limit, + that is ALL. :-) Well, it does not remove the problem completely, + but exponential growth of network traffic is changed to linear + (branches, that exceed pmtu are pruned) and tunnel mtu + fastly degrades to value <68, where looping stops. + Yes, it is not good if there exists a router in the loop, + which does not force DF, even when encapsulating packets have DF set. + But it is not our problem! Nobody could accuse us, we made + all that we could make. Even if it is your gated who injected + fatal route to network, even if it were you who configured + fatal static route: you are innocent. :-) + + + + 3. Really, ipv4/ipip.c, ipv4/ip_gre.c and ipv6/sit.c contain + practically identical code. It would be good to glue them + together, but it is not very evident, how to make them modular. + sit is integral part of IPv6, ipip and gre are naturally modular. + We could extract common parts (hash table, ioctl etc) + to a separate module (ip_tunnel.c). + + Alexey Kuznetsov. + */ + +static int ipgre_tunnel_init(struct net_device *dev); +static void ipgre_tunnel_setup(struct net_device *dev); + +/* Fallback tunnel: no source, no destination, no key, no options */ + +static int ipgre_fb_tunnel_init(struct net_device *dev); + +static struct net_device *ipgre_fb_tunnel_dev; + +/* Tunnel hash table */ + +/* + 4 hash tables: + + 3: (remote,local) + 2: (remote,*) + 1: (*,local) + 0: (*,*) + + We require exact key match i.e. if a key is present in packet + it will match only tunnel with the same key; if it is not present, + it will match only keyless tunnel. + + All keysless packets, if not matched configured keyless tunnels + will match fallback tunnel. + */ + +#define HASH_SIZE 16 +#define HASH(addr) ((addr^(addr>>4))&0xF) + +static struct ip_tunnel *tunnels[4][HASH_SIZE]; + +#define tunnels_r_l (tunnels[3]) +#define tunnels_r (tunnels[2]) +#define tunnels_l (tunnels[1]) +#define tunnels_wc (tunnels[0]) + +static DEFINE_RWLOCK(ipgre_lock); + +/* Given src, dst and key, find appropriate for input tunnel. */ + +static struct ip_tunnel * ipgre_tunnel_lookup(u32 remote, u32 local, u32 key) +{ + unsigned h0 = HASH(remote); + unsigned h1 = HASH(key); + 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) { + if (t->parms.i_key == key && (t->dev->flags&IFF_UP)) + return t; + } + } + for (t = tunnels_r[h0^h1]; t; t = t->next) { + if (remote == t->parms.iph.daddr) { + if (t->parms.i_key == key && (t->dev->flags&IFF_UP)) + return t; + } + } + for (t = tunnels_l[h1]; t; t = t->next) { + if (local == t->parms.iph.saddr || + (local == t->parms.iph.daddr && MULTICAST(local))) { + if (t->parms.i_key == key && (t->dev->flags&IFF_UP)) + return t; + } + } + for (t = tunnels_wc[h1]; t; t = t->next) { + if (t->parms.i_key == key && (t->dev->flags&IFF_UP)) + return t; + } + + if (ipgre_fb_tunnel_dev->flags&IFF_UP) + return ipgre_fb_tunnel_dev->priv; + return NULL; +} + +static struct ip_tunnel **ipgre_bucket(struct ip_tunnel *t) +{ + u32 remote = t->parms.iph.daddr; + u32 local = t->parms.iph.saddr; + u32 key = t->parms.i_key; + unsigned h = HASH(key); + int prio = 0; + + if (local) + prio |= 1; + if (remote && !MULTICAST(remote)) { + prio |= 2; + h ^= HASH(remote); + } + + return &tunnels[prio][h]; +} + +static void ipgre_tunnel_link(struct ip_tunnel *t) +{ + struct ip_tunnel **tp = ipgre_bucket(t); + + t->next = *tp; + write_lock_bh(&ipgre_lock); + *tp = t; + write_unlock_bh(&ipgre_lock); +} + +static void ipgre_tunnel_unlink(struct ip_tunnel *t) +{ + struct ip_tunnel **tp; + + for (tp = ipgre_bucket(t); *tp; tp = &(*tp)->next) { + if (t == *tp) { + write_lock_bh(&ipgre_lock); + *tp = t->next; + write_unlock_bh(&ipgre_lock); + break; + } + } +} + +static struct ip_tunnel * ipgre_tunnel_locate(struct ip_tunnel_parm *parms, int create) +{ + u32 remote = parms->iph.daddr; + u32 local = parms->iph.saddr; + u32 key = parms->i_key; + struct ip_tunnel *t, **tp, *nt; + struct net_device *dev; + unsigned h = HASH(key); + int prio = 0; + char name[IFNAMSIZ]; + + if (local) + prio |= 1; + if (remote && !MULTICAST(remote)) { + prio |= 2; + h ^= HASH(remote); + } + for (tp = &tunnels[prio][h]; (t = *tp) != NULL; tp = &t->next) { + if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr) { + if (key == t->parms.i_key) + return t; + } + } + if (!create) + return NULL; + + if (parms->name[0]) + strlcpy(name, parms->name, IFNAMSIZ); + else { + int i; + for (i=1; i<100; i++) { + sprintf(name, "gre%d", i); + if (__dev_get_by_name(name) == NULL) + break; + } + if (i==100) + goto failed; + } + + dev = alloc_netdev(sizeof(*t), name, ipgre_tunnel_setup); + if (!dev) + return NULL; + + dev->init = ipgre_tunnel_init; + nt = dev->priv; + nt->parms = *parms; + + if (register_netdevice(dev) < 0) { + free_netdev(dev); + goto failed; + } + + nt = dev->priv; + nt->parms = *parms; + + dev_hold(dev); + ipgre_tunnel_link(nt); + /* Do not decrement MOD_USE_COUNT here. */ + return nt; + +failed: + return NULL; +} + +static void ipgre_tunnel_uninit(struct net_device *dev) +{ + ipgre_tunnel_unlink((struct ip_tunnel*)dev->priv); + dev_put(dev); +} + + +static void ipgre_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. + + Moreover, Cisco "wise men" put GRE key to the third word + in GRE header. It makes impossible maintaining even soft state for keyed + GRE tunnels with enabled checksum. Tell them "thank you". + + Well, I wonder, rfc1812 was written by Cisco employee, + what the hell these idiots break standrads established + by themself??? + */ + + struct iphdr *iph = (struct iphdr*)skb->data; + u16 *p = (u16*)(skb->data+(iph->ihl<<2)); + int grehlen = (iph->ihl<<2) + 4; + int type = skb->h.icmph->type; + int code = skb->h.icmph->code; + struct ip_tunnel *t; + u16 flags; + + flags = p[0]; + if (flags&(GRE_CSUM|GRE_KEY|GRE_SEQ|GRE_ROUTING|GRE_VERSION)) { + if (flags&(GRE_VERSION|GRE_ROUTING)) + return; + if (flags&GRE_KEY) { + grehlen += 4; + if (flags&GRE_CSUM) + grehlen += 4; + } + } + + /* If only 8 bytes returned, keyed message will be dropped here */ + if (skb_headlen(skb) < grehlen) + return; + + 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(&ipgre_lock); + t = ipgre_tunnel_lookup(iph->daddr, iph->saddr, (flags&GRE_KEY) ? *(((u32*)p) + (grehlen>>2) - 1) : 0); + if (t == NULL || t->parms.iph.daddr == 0 || MULTICAST(t->parms.iph.daddr)) + 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(&ipgre_lock); + return; +#else + struct iphdr *iph = (struct iphdr*)dp; + struct iphdr *eiph; + u16 *p = (u16*)(dp+(iph->ihl<<2)); + int type = skb->h.icmph->type; + int code = skb->h.icmph->code; + int rel_type = 0; + int rel_code = 0; + int rel_info = 0; + u16 flags; + int grehlen = (iph->ihl<<2) + 4; + struct sk_buff *skb2; + struct flowi fl; + struct rtable *rt; + + if (p[1] != htons(ETH_P_IP)) + return; + + flags = p[0]; + if (flags&(GRE_CSUM|GRE_KEY|GRE_SEQ|GRE_ROUTING|GRE_VERSION)) { + if (flags&(GRE_VERSION|GRE_ROUTING)) + return; + if (flags&GRE_CSUM) + grehlen += 4; + if (flags&GRE_KEY) + grehlen += 4; + if (flags&GRE_SEQ) + grehlen += 4; + } + if (len < grehlen + sizeof(struct iphdr)) + return; + eiph = (struct iphdr*)(dp + grehlen); + + switch (type) { + default: + return; + case ICMP_PARAMETERPROB: + if (skb->h.icmph->un.gateway < (iph->ihl<<2)) + return; + + /* So... This guy found something strange INSIDE encapsulated + packet. Well, he is fool, but what can we do ? + */ + rel_type = ICMP_PARAMETERPROB; + rel_info = skb->h.icmph->un.gateway - grehlen; + break; + + case ICMP_DEST_UNREACH: + switch (code) { + case ICMP_SR_FAILED: + case ICMP_PORT_UNREACH: + /* Impossible event. */ + return; + case ICMP_FRAG_NEEDED: + /* And it is the only really necessary thing :-) */ + rel_info = ntohs(skb->h.icmph->un.frag.mtu); + if (rel_info < grehlen+68) + return; + rel_info -= grehlen; + /* BSD 4.2 MORE DOES NOT EXIST IN NATURE. */ + if (rel_info > ntohs(eiph->tot_len)) + return; + break; + 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 = ICMP_DEST_UNREACH; + rel_code = ICMP_HOST_UNREACH; + break; + } + break; + case ICMP_TIME_EXCEEDED: + if (code != ICMP_EXC_TTL) + return; + break; + } + + /* Prepare fake skb to feed it to icmp_send */ + skb2 = skb_clone(skb, GFP_ATOMIC); + if (skb2 == NULL) + return; + dst_release(skb2->dst); + skb2->dst = NULL; + skb_pull(skb2, skb->data - (u8*)eiph); + skb2->nh.raw = skb2->data; + + /* Try to guess incoming interface */ + memset(&fl, 0, sizeof(fl)); + fl.fl4_dst = eiph->saddr; + fl.fl4_tos = RT_TOS(eiph->tos); + fl.proto = IPPROTO_GRE; + if (ip_route_output_key(&rt, &fl)) { + kfree_skb(skb2); + return; + } + skb2->dev = rt->u.dst.dev; + + /* route "incoming" packet */ + if (rt->rt_flags&RTCF_LOCAL) { + ip_rt_put(rt); + rt = NULL; + fl.fl4_dst = eiph->daddr; + fl.fl4_src = eiph->saddr; + fl.fl4_tos = eiph->tos; + if (ip_route_output_key(&rt, &fl) || + rt->u.dst.dev->type != ARPHRD_IPGRE) { + ip_rt_put(rt); + kfree_skb(skb2); + return; + } + } else { + ip_rt_put(rt); + if (ip_route_input(skb2, eiph->daddr, eiph->saddr, eiph->tos, skb2->dev) || + skb2->dst->dev->type != ARPHRD_IPGRE) { + kfree_skb(skb2); + return; + } + } + + /* change mtu on this route */ + if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) { + if (rel_info > dst_mtu(skb2->dst)) { + kfree_skb(skb2); + return; + } + skb2->dst->ops->update_pmtu(skb2->dst, rel_info); + rel_info = htonl(rel_info); + } else if (type == ICMP_TIME_EXCEEDED) { + struct ip_tunnel *t = (struct ip_tunnel*)skb2->dev->priv; + if (t->parms.iph.ttl) { + rel_type = ICMP_DEST_UNREACH; + rel_code = ICMP_HOST_UNREACH; + } + } + + icmp_send(skb2, rel_type, rel_code, rel_info); + kfree_skb(skb2); +#endif +} + +static inline void ipgre_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb) +{ + if (INET_ECN_is_ce(iph->tos)) { + if (skb->protocol == htons(ETH_P_IP)) { + IP_ECN_set_ce(skb->nh.iph); + } else if (skb->protocol == htons(ETH_P_IPV6)) { + IP6_ECN_set_ce(skb->nh.ipv6h); + } + } +} + +static inline u8 +ipgre_ecn_encapsulate(u8 tos, struct iphdr *old_iph, struct sk_buff *skb) +{ + u8 inner = 0; + if (skb->protocol == htons(ETH_P_IP)) + inner = old_iph->tos; + else if (skb->protocol == htons(ETH_P_IPV6)) + inner = ipv6_get_dsfield((struct ipv6hdr *)old_iph); + return INET_ECN_encapsulate(tos, inner); +} + +static int ipgre_rcv(struct sk_buff *skb) +{ + struct iphdr *iph; + u8 *h; + u16 flags; + u16 csum = 0; + u32 key = 0; + u32 seqno = 0; + struct ip_tunnel *tunnel; + int offset = 4; + + if (!pskb_may_pull(skb, 16)) + goto drop_nolock; + + iph = skb->nh.iph; + h = skb->data; + flags = *(u16*)h; + + if (flags&(GRE_CSUM|GRE_KEY|GRE_ROUTING|GRE_SEQ|GRE_VERSION)) { + /* - Version must be 0. + - We do not support routing headers. + */ + if (flags&(GRE_VERSION|GRE_ROUTING)) + goto drop_nolock; + + if (flags&GRE_CSUM) { + if (skb->ip_summed == CHECKSUM_HW) { + csum = (u16)csum_fold(skb->csum); + if (csum) + skb->ip_summed = CHECKSUM_NONE; + } + if (skb->ip_summed == CHECKSUM_NONE) { + skb->csum = skb_checksum(skb, 0, skb->len, 0); + skb->ip_summed = CHECKSUM_HW; + csum = (u16)csum_fold(skb->csum); + } + offset += 4; + } + if (flags&GRE_KEY) { + key = *(u32*)(h + offset); + offset += 4; + } + if (flags&GRE_SEQ) { + seqno = ntohl(*(u32*)(h + offset)); + offset += 4; + } + } + + read_lock(&ipgre_lock); + if ((tunnel = ipgre_tunnel_lookup(iph->saddr, iph->daddr, key)) != NULL) { + secpath_reset(skb); + + skb->protocol = *(u16*)(h + 2); + /* WCCP version 1 and 2 protocol decoding. + * - Change protocol to IP + * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header + */ + if (flags == 0 && + skb->protocol == __constant_htons(ETH_P_WCCP)) { + skb->protocol = __constant_htons(ETH_P_IP); + if ((*(h + offset) & 0xF0) != 0x40) + offset += 4; + } + + skb->mac.raw = skb->nh.raw; + skb->nh.raw = __pskb_pull(skb, offset); + skb_postpull_rcsum(skb, skb->mac.raw, offset); + memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options)); + skb->pkt_type = PACKET_HOST; +#ifdef CONFIG_NET_IPGRE_BROADCAST + if (MULTICAST(iph->daddr)) { + /* Looped back packet, drop it! */ + if (((struct rtable*)skb->dst)->fl.iif == 0) + goto drop; + tunnel->stat.multicast++; + skb->pkt_type = PACKET_BROADCAST; + } +#endif + + if (((flags&GRE_CSUM) && csum) || + (!(flags&GRE_CSUM) && tunnel->parms.i_flags&GRE_CSUM)) { + tunnel->stat.rx_crc_errors++; + tunnel->stat.rx_errors++; + goto drop; + } + if (tunnel->parms.i_flags&GRE_SEQ) { + if (!(flags&GRE_SEQ) || + (tunnel->i_seqno && (s32)(seqno - tunnel->i_seqno) < 0)) { + tunnel->stat.rx_fifo_errors++; + tunnel->stat.rx_errors++; + goto drop; + } + tunnel->i_seqno = seqno + 1; + } + tunnel->stat.rx_packets++; + tunnel->stat.rx_bytes += skb->len; + skb->dev = tunnel->dev; + dst_release(skb->dst); + skb->dst = NULL; + nf_reset(skb); + ipgre_ecn_decapsulate(iph, skb); + netif_rx(skb); + read_unlock(&ipgre_lock); + return(0); + } + icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PROT_UNREACH, 0); + +drop: + read_unlock(&ipgre_lock); +drop_nolock: + kfree_skb(skb); + return(0); +} + +static int ipgre_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 *old_iph = skb->nh.iph; + struct iphdr *tiph; + u8 tos; + u16 df; + 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 */ + int gre_hlen; + u32 dst; + int mtu; + + if (tunnel->recursion++) { + tunnel->stat.collisions++; + goto tx_error; + } + + if (dev->hard_header) { + gre_hlen = 0; + tiph = (struct iphdr*)skb->data; + } else { + gre_hlen = tunnel->hlen; + tiph = &tunnel->parms.iph; + } + + if ((dst = tiph->daddr) == 0) { + /* NBMA tunnel */ + + if (skb->dst == NULL) { + tunnel->stat.tx_fifo_errors++; + goto tx_error; + } + + if (skb->protocol == htons(ETH_P_IP)) { + rt = (struct rtable*)skb->dst; + if ((dst = rt->rt_gateway) == 0) + goto tx_error_icmp; + } +#ifdef CONFIG_IPV6 + else if (skb->protocol == htons(ETH_P_IPV6)) { + struct in6_addr *addr6; + int addr_type; + struct neighbour *neigh = skb->dst->neighbour; + + if (neigh == NULL) + 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]; + } +#endif + else + goto tx_error; + } + + tos = tiph->tos; + if (tos&1) { + if (skb->protocol == htons(ETH_P_IP)) + tos = old_iph->tos; + tos &= ~1; + } + + { + struct flowi fl = { .oif = tunnel->parms.link, + .nl_u = { .ip4_u = + { .daddr = dst, + .saddr = tiph->saddr, + .tos = RT_TOS(tos) } }, + .proto = IPPROTO_GRE }; + if (ip_route_output_key(&rt, &fl)) { + tunnel->stat.tx_carrier_errors++; + goto tx_error; + } + } + tdev = rt->u.dst.dev; + + if (tdev == dev) { + ip_rt_put(rt); + tunnel->stat.collisions++; + goto tx_error; + } + + df = tiph->frag_off; + if (df) + mtu = dst_mtu(&rt->u.dst) - tunnel->hlen; + else + mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu; + + if (skb->dst) + skb->dst->ops->update_pmtu(skb->dst, mtu); + + if (skb->protocol == htons(ETH_P_IP)) { + df |= (old_iph->frag_off&htons(IP_DF)); + + if ((old_iph->frag_off&htons(IP_DF)) && + mtu < ntohs(old_iph->tot_len)) { + icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu)); + ip_rt_put(rt); + goto tx_error; + } + } +#ifdef CONFIG_IPV6 + else if (skb->protocol == htons(ETH_P_IPV6)) { + struct rt6_info *rt6 = (struct rt6_info*)skb->dst; + + if (rt6 && mtu < dst_mtu(skb->dst) && mtu >= IPV6_MIN_MTU) { + if ((tunnel->parms.iph.daddr && !MULTICAST(tunnel->parms.iph.daddr)) || + rt6->rt6i_dst.plen == 128) { + rt6->rt6i_flags |= RTF_MODIFIED; + skb->dst->metrics[RTAX_MTU-1] = mtu; + } + } + + if (mtu >= IPV6_MIN_MTU && mtu < skb->len - tunnel->hlen + gre_hlen) { + icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev); + ip_rt_put(rt); + goto tx_error; + } + } +#endif + + 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; + } + + max_headroom = LL_RESERVED_SPACE(tdev) + gre_hlen; + + 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; + old_iph = skb->nh.iph; + } + + skb->h.raw = skb->nh.raw; + skb->nh.raw = skb_push(skb, gre_hlen); + 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; + iph->frag_off = df; + iph->protocol = IPPROTO_GRE; + iph->tos = ipgre_ecn_encapsulate(tos, old_iph, skb); + iph->daddr = rt->rt_dst; + iph->saddr = rt->rt_src; + + if ((iph->ttl = tiph->ttl) == 0) { + if (skb->protocol == htons(ETH_P_IP)) + iph->ttl = old_iph->ttl; +#ifdef CONFIG_IPV6 + else if (skb->protocol == htons(ETH_P_IPV6)) + iph->ttl = ((struct ipv6hdr*)old_iph)->hop_limit; +#endif + else + iph->ttl = dst_metric(&rt->u.dst, RTAX_HOPLIMIT); + } + + ((u16*)(iph+1))[0] = tunnel->parms.o_flags; + ((u16*)(iph+1))[1] = skb->protocol; + + if (tunnel->parms.o_flags&(GRE_KEY|GRE_CSUM|GRE_SEQ)) { + u32 *ptr = (u32*)(((u8*)iph) + tunnel->hlen - 4); + + if (tunnel->parms.o_flags&GRE_SEQ) { + ++tunnel->o_seqno; + *ptr = htonl(tunnel->o_seqno); + ptr--; + } + if (tunnel->parms.o_flags&GRE_KEY) { + *ptr = tunnel->parms.o_key; + ptr--; + } + if (tunnel->parms.o_flags&GRE_CSUM) { + *ptr = 0; + *(__u16*)ptr = ip_compute_csum((void*)(iph+1), skb->len - sizeof(struct iphdr)); + } + } + + 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 +ipgre_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 == ipgre_fb_tunnel_dev) { + if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) { + err = -EFAULT; + break; + } + t = ipgre_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_GRE || + p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)) || + ((p.i_flags|p.o_flags)&(GRE_VERSION|GRE_ROUTING))) + goto done; + if (p.iph.ttl) + p.iph.frag_off |= htons(IP_DF); + + if (!(p.i_flags&GRE_KEY)) + p.i_key = 0; + if (!(p.o_flags&GRE_KEY)) + p.o_key = 0; + + t = ipgre_tunnel_locate(&p, cmd == SIOCADDTUNNEL); + + if (dev != ipgre_fb_tunnel_dev && cmd == SIOCCHGTUNNEL) { + if (t != NULL) { + if (t->dev != dev) { + err = -EEXIST; + break; + } + } else { + unsigned nflags=0; + + t = (struct ip_tunnel*)dev->priv; + + if (MULTICAST(p.iph.daddr)) + nflags = IFF_BROADCAST; + else if (p.iph.daddr) + nflags = IFF_POINTOPOINT; + + if ((dev->flags^nflags)&(IFF_POINTOPOINT|IFF_BROADCAST)) { + err = -EINVAL; + break; + } + ipgre_tunnel_unlink(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; + memcpy(dev->dev_addr, &p.iph.saddr, 4); + memcpy(dev->broadcast, &p.iph.daddr, 4); + ipgre_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; + t->parms.iph.frag_off = p.iph.frag_off; + } + 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 == ipgre_fb_tunnel_dev) { + err = -EFAULT; + if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) + goto done; + err = -ENOENT; + if ((t = ipgre_tunnel_locate(&p, 0)) == NULL) + goto done; + err = -EPERM; + if (t == ipgre_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 *ipgre_tunnel_get_stats(struct net_device *dev) +{ + return &(((struct ip_tunnel*)dev->priv)->stat); +} + +static int ipgre_tunnel_change_mtu(struct net_device *dev, int new_mtu) +{ + struct ip_tunnel *tunnel = (struct ip_tunnel*)dev->priv; + if (new_mtu < 68 || new_mtu > 0xFFF8 - tunnel->hlen) + return -EINVAL; + dev->mtu = new_mtu; + return 0; +} + +#ifdef CONFIG_NET_IPGRE_BROADCAST +/* Nice toy. Unfortunately, useless in real life :-) + It allows to construct virtual multiprotocol broadcast "LAN" + over the Internet, provided multicast routing is tuned. + + + I have no idea was this bicycle invented before me, + so that I had to set ARPHRD_IPGRE to a random value. + I have an impression, that Cisco could make something similar, + but this feature is apparently missing in IOS<=11.2(8). + + I set up 10.66.66/24 and fec0:6666:6666::0/96 as virtual networks + with broadcast 224.66.66.66. If you have access to mbone, play with me :-) + + ping -t 255 224.66.66.66 + + If nobody answers, mbone does not work. + + ip tunnel add Universe mode gre remote 224.66.66.66 local <Your_real_addr> ttl 255 + ip addr add 10.66.66.<somewhat>/24 dev Universe + ifconfig Universe up + ifconfig Universe add fe80::<Your_real_addr>/10 + ifconfig Universe add fec0:6666:6666::<Your_real_addr>/96 + ftp 10.66.66.66 + ... + ftp fec0:6666:6666::193.233.7.65 + ... + + */ + +static int ipgre_header(struct sk_buff *skb, struct net_device *dev, unsigned short type, + void *daddr, void *saddr, unsigned len) +{ + struct ip_tunnel *t = (struct ip_tunnel*)dev->priv; + struct iphdr *iph = (struct iphdr *)skb_push(skb, t->hlen); + u16 *p = (u16*)(iph+1); + + memcpy(iph, &t->parms.iph, sizeof(struct iphdr)); + p[0] = t->parms.o_flags; + p[1] = htons(type); + + /* + * Set the source hardware address. + */ + + if (saddr) + memcpy(&iph->saddr, saddr, 4); + + if (daddr) { + memcpy(&iph->daddr, daddr, 4); + return t->hlen; + } + if (iph->daddr && !MULTICAST(iph->daddr)) + return t->hlen; + + return -t->hlen; +} + +static int ipgre_open(struct net_device *dev) +{ + struct ip_tunnel *t = (struct ip_tunnel*)dev->priv; + + if (MULTICAST(t->parms.iph.daddr)) { + struct flowi fl = { .oif = t->parms.link, + .nl_u = { .ip4_u = + { .daddr = t->parms.iph.daddr, + .saddr = t->parms.iph.saddr, + .tos = RT_TOS(t->parms.iph.tos) } }, + .proto = IPPROTO_GRE }; + struct rtable *rt; + if (ip_route_output_key(&rt, &fl)) + return -EADDRNOTAVAIL; + dev = rt->u.dst.dev; + ip_rt_put(rt); + if (__in_dev_get(dev) == NULL) + return -EADDRNOTAVAIL; + t->mlink = dev->ifindex; + ip_mc_inc_group(__in_dev_get(dev), t->parms.iph.daddr); + } + return 0; +} + +static int ipgre_close(struct net_device *dev) +{ + struct ip_tunnel *t = (struct ip_tunnel*)dev->priv; + if (MULTICAST(t->parms.iph.daddr) && t->mlink) { + struct in_device *in_dev = inetdev_by_index(t->mlink); + if (in_dev) { + ip_mc_dec_group(in_dev, t->parms.iph.daddr); + in_dev_put(in_dev); + } + } + return 0; +} + +#endif + +static void ipgre_tunnel_setup(struct net_device *dev) +{ + SET_MODULE_OWNER(dev); + dev->uninit = ipgre_tunnel_uninit; + dev->destructor = free_netdev; + dev->hard_start_xmit = ipgre_tunnel_xmit; + dev->get_stats = ipgre_tunnel_get_stats; + dev->do_ioctl = ipgre_tunnel_ioctl; + dev->change_mtu = ipgre_tunnel_change_mtu; + + dev->type = ARPHRD_IPGRE; + dev->hard_header_len = LL_MAX_HEADER + sizeof(struct iphdr) + 4; + dev->mtu = 1500 - sizeof(struct iphdr) - 4; + dev->flags = IFF_NOARP; + dev->iflink = 0; + dev->addr_len = 4; +} + +static int ipgre_tunnel_init(struct net_device *dev) +{ + struct net_device *tdev = NULL; + struct ip_tunnel *tunnel; + struct iphdr *iph; + int hlen = LL_MAX_HEADER; + int mtu = 1500; + int addend = sizeof(struct iphdr) + 4; + + 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); + + /* Guess output device to choose reasonable mtu and hard_header_len */ + + if (iph->daddr) { + struct flowi fl = { .oif = tunnel->parms.link, + .nl_u = { .ip4_u = + { .daddr = iph->daddr, + .saddr = iph->saddr, + .tos = RT_TOS(iph->tos) } }, + .proto = IPPROTO_GRE }; + struct rtable *rt; + if (!ip_route_output_key(&rt, &fl)) { + tdev = rt->u.dst.dev; + ip_rt_put(rt); + } + + dev->flags |= IFF_POINTOPOINT; + +#ifdef CONFIG_NET_IPGRE_BROADCAST + if (MULTICAST(iph->daddr)) { + if (!iph->saddr) + return -EINVAL; + dev->flags = IFF_BROADCAST; + dev->hard_header = ipgre_header; + dev->open = ipgre_open; + dev->stop = ipgre_close; + } +#endif + } + + if (!tdev && tunnel->parms.link) + tdev = __dev_get_by_index(tunnel->parms.link); + + if (tdev) { + hlen = tdev->hard_header_len; + mtu = tdev->mtu; + } + dev->iflink = tunnel->parms.link; + + /* Precalculate GRE options length */ + if (tunnel->parms.o_flags&(GRE_CSUM|GRE_KEY|GRE_SEQ)) { + if (tunnel->parms.o_flags&GRE_CSUM) + addend += 4; + if (tunnel->parms.o_flags&GRE_KEY) + addend += 4; + if (tunnel->parms.o_flags&GRE_SEQ) + addend += 4; + } + dev->hard_header_len = hlen + addend; + dev->mtu = mtu - addend; + tunnel->hlen = addend; + return 0; +} + +int __init ipgre_fb_tunnel_init(struct net_device *dev) +{ + struct ip_tunnel *tunnel = (struct ip_tunnel*)dev->priv; + struct iphdr *iph = &tunnel->parms.iph; + + tunnel->dev = dev; + strcpy(tunnel->parms.name, dev->name); + + iph->version = 4; + iph->protocol = IPPROTO_GRE; + iph->ihl = 5; + tunnel->hlen = sizeof(struct iphdr) + 4; + + dev_hold(dev); + tunnels_wc[0] = tunnel; + return 0; +} + + +static struct net_protocol ipgre_protocol = { + .handler = ipgre_rcv, + .err_handler = ipgre_err, +}; + + +/* + * And now the modules code and kernel interface. + */ + +static int __init ipgre_init(void) +{ + int err; + + printk(KERN_INFO "GRE over IPv4 tunneling driver\n"); + + if (inet_add_protocol(&ipgre_protocol, IPPROTO_GRE) < 0) { + printk(KERN_INFO "ipgre init: can't add protocol\n"); + return -EAGAIN; + } + + ipgre_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "gre0", + ipgre_tunnel_setup); + if (!ipgre_fb_tunnel_dev) { + err = -ENOMEM; + goto err1; + } + + ipgre_fb_tunnel_dev->init = ipgre_fb_tunnel_init; + + if ((err = register_netdev(ipgre_fb_tunnel_dev))) + goto err2; +out: + return err; +err2: + free_netdev(ipgre_fb_tunnel_dev); +err1: + inet_del_protocol(&ipgre_protocol, IPPROTO_GRE); + goto out; +} + +static void ipgre_fini(void) +{ + if (inet_del_protocol(&ipgre_protocol, IPPROTO_GRE) < 0) + printk(KERN_INFO "ipgre close: can't remove protocol\n"); + + unregister_netdev(ipgre_fb_tunnel_dev); +} + +module_init(ipgre_init); +module_exit(ipgre_fini); +MODULE_LICENSE("GPL"); |