patch-2.1.68 linux/net/ipv4/ip_gre.c
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- Lines: 1192
- Date:
Sun Nov 30 14:00:39 1997
- Orig file:
v2.1.67/linux/net/ipv4/ip_gre.c
- Orig date:
Wed Dec 31 16:00:00 1969
diff -u --recursive --new-file v2.1.67/linux/net/ipv4/ip_gre.c linux/net/ipv4/ip_gre.c
@@ -0,0 +1,1191 @@
+/*
+ * 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 <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>
+
+#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 device *dev);
+
+/* Fallback tunnel: no source, no destination, no key, no options */
+
+static int ipgre_fb_tunnel_init(struct device *dev);
+
+static struct device ipgre_fb_tunnel_dev = {
+ NULL, 0x0, 0x0, 0x0, 0x0, 0, 0, 0, 0, 0, NULL, ipgre_fb_tunnel_init,
+};
+
+static struct ip_tunnel ipgre_fb_tunnel = {
+ NULL, &ipgre_fb_tunnel_dev, {0, }, 0, 0, 0, 0, 0, 0, 0, {"gre0", }
+};
+
+/* 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])
+
+/* Given src, dst and key, find approriate 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;
+ return NULL;
+}
+
+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 device *dev;
+ unsigned h = HASH(key);
+ int prio = 0;
+
+ 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;
+
+ MOD_INC_USE_COUNT;
+ dev = kmalloc(sizeof(*dev) + sizeof(*t), GFP_KERNEL);
+ if (dev == NULL) {
+ MOD_DEC_USE_COUNT;
+ return NULL;
+ }
+ memset(dev, 0, sizeof(*dev) + sizeof(*t));
+ dev->priv = (void*)(dev+1);
+ nt = (struct ip_tunnel*)dev->priv;
+ nt->dev = dev;
+ dev->name = nt->parms.name;
+ dev->init = ipgre_tunnel_init;
+ memcpy(&nt->parms, parms, sizeof(*parms));
+ if (dev->name[0] == 0) {
+ int i;
+ for (i=1; i<100; i++) {
+ sprintf(dev->name, "gre%d", i);
+ if (dev_get(dev->name) == NULL)
+ break;
+ }
+ if (i==100)
+ goto failed;
+ memcpy(parms->name, dev->name, IFNAMSIZ);
+ }
+ if (register_netdevice(dev) < 0)
+ goto failed;
+
+ start_bh_atomic();
+ nt->next = t;
+ *tp = nt;
+ end_bh_atomic();
+ /* Do not decrement MOD_USE_COUNT here. */
+ return nt;
+
+failed:
+ kfree(dev);
+ MOD_DEC_USE_COUNT;
+ return NULL;
+}
+
+static void ipgre_tunnel_destroy(struct device *dev)
+{
+ struct ip_tunnel *t, **tp;
+ struct ip_tunnel *t0 = (struct ip_tunnel*)dev->priv;
+ u32 remote = t0->parms.iph.daddr;
+ u32 local = t0->parms.iph.saddr;
+ unsigned h = HASH(t0->parms.i_key);
+ int prio = 0;
+
+ 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 (t == t0) {
+ *tp = t->next;
+ if (dev != &ipgre_fb_tunnel_dev) {
+ kfree(dev);
+ MOD_DEC_USE_COUNT;
+ }
+ break;
+ }
+ }
+}
+
+
+void ipgre_err(struct sk_buff *skb, unsigned char *dp, int len)
+{
+#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*)dp;
+ u16 *p = (u16*)(dp+(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 (len < 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;
+ }
+
+ 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))
+ return;
+
+ if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
+ return;
+
+ if (jiffies - t->err_time < IPTUNNEL_ERR_TIMEO)
+ t->err_count++;
+ else
+ t->err_count = 1;
+ t->err_time = jiffies;
+ 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 rtable *rt;
+
+ if (p[1] != __constant_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 necesary 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 */
+ if (ip_route_output(&rt, eiph->saddr, 0, RT_TOS(eiph->tos), 0)) {
+ kfree_skb(skb2, FREE_WRITE);
+ return;
+ }
+ skb2->dev = rt->u.dst.dev;
+
+ /* route "incoming" packet */
+ if (rt->rt_flags&RTCF_LOCAL) {
+ ip_rt_put(rt);
+ rt = NULL;
+ if (ip_route_output(&rt, eiph->daddr, eiph->saddr, eiph->tos, 0) ||
+ rt->u.dst.dev->type != ARPHRD_IPGRE) {
+ ip_rt_put(rt);
+ kfree_skb(skb2, FREE_WRITE);
+ 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, FREE_WRITE);
+ return;
+ }
+ }
+
+ /* change mtu on this route */
+ if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
+ if (rel_info > skb2->dst->pmtu) {
+ kfree_skb(skb2, FREE_WRITE);
+ return;
+ }
+ skb2->dst->pmtu = 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, FREE_WRITE);
+#endif
+}
+
+int ipgre_rcv(struct sk_buff *skb, unsigned short len)
+{
+ struct iphdr *iph = skb->nh.iph;
+ u8 *h = skb->h.raw;
+ u16 flags = *(u16*)h;
+ u16 csum = 0;
+ u32 key = 0;
+ u32 seqno = 0;
+ struct ip_tunnel *tunnel;
+ int offset = 4;
+
+ 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;
+
+ if (flags&GRE_CSUM) {
+ csum = ip_compute_csum(h, len);
+ offset += 4;
+ }
+ if (flags&GRE_KEY) {
+ key = *(u32*)(h + offset);
+ offset += 4;
+ }
+ if (flags&GRE_SEQ) {
+ seqno = ntohl(*(u32*)(h + offset));
+ offset += 4;
+ }
+ }
+
+ if ((tunnel = ipgre_tunnel_lookup(iph->saddr, iph->daddr, key)) != NULL) {
+ skb->mac.raw = skb->nh.raw;
+ skb->nh.raw = skb_pull(skb, h + offset - skb->data);
+ memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
+ skb->ip_summed = 0;
+ skb->protocol = *(u16*)(h + 2);
+ skb->pkt_type = PACKET_HOST;
+#ifdef CONFIG_NET_IPGRE_BROADCAST
+ if (MULTICAST(iph->daddr)) {
+ /* Looped back packet, drop it! */
+ if (((struct rtable*)skb->dst)->key.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 && 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;
+ netif_rx(skb);
+ return(0);
+ }
+ icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PROT_UNREACH, 0);
+
+drop:
+ kfree_skb(skb, FREE_READ);
+ return(0);
+}
+
+static int ipgre_tunnel_xmit(struct sk_buff *skb, struct 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 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 == __constant_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 == __constant_htons(ETH_P_IPV6)) {
+ struct in6_addr *addr6;
+ int addr_type;
+ struct nd_neigh *neigh = (struct nd_neigh *) skb->dst->neighbour;
+
+ if (neigh == NULL)
+ goto tx_error;
+
+ addr6 = &neigh->ndn_addr;
+ 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 == __constant_htons(ETH_P_IP))
+ tos = old_iph->tos;
+ tos &= ~1;
+ }
+
+ if (ip_route_output(&rt, dst, tiph->saddr, RT_TOS(tos), tunnel->parms.link)) {
+ 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;
+ mtu = rt->u.dst.pmtu - tunnel->hlen;
+
+ if (skb->protocol == __constant_htons(ETH_P_IP)) {
+ if (skb->dst && mtu < skb->dst->pmtu && mtu >= 68)
+ skb->dst->pmtu = mtu;
+
+ df |= (old_iph->frag_off&__constant_htons(IP_DF));
+
+ if ((old_iph->frag_off&__constant_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 == __constant_htons(ETH_P_IPV6)) {
+ struct rt6_info *rt6 = (struct rt6_info*)skb->dst;
+
+ if (rt6 && mtu < rt6->u.dst.pmtu && mtu >= 576) {
+ if ((tunnel->parms.iph.daddr && !MULTICAST(tunnel->parms.iph.daddr)) ||
+ rt6->rt6i_dst.plen == 128) {
+ rt6->rt6i_flags |= RTF_MODIFIED;
+ skb->dst->pmtu = mtu;
+ }
+ }
+
+ if (mtu >= 576 && 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--;
+
+ if (skb->protocol == __constant_htons(ETH_P_IP))
+ icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
+#ifdef CONFIG_IPV6
+ else if (skb->protocol == __constant_htons(ETH_P_IPV6))
+ icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_ADDR_UNREACH, 0, dev);
+#endif
+ } else
+ tunnel->err_count = 0;
+ }
+
+ skb->h.raw = skb->nh.raw;
+
+ max_headroom = ((tdev->hard_header_len+15)&~15)+ 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, FREE_WRITE);
+ tunnel->recursion--;
+ return 0;
+ }
+ dev_kfree_skb(skb, FREE_WRITE);
+ skb = new_skb;
+ }
+
+ 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 = tos;
+ iph->daddr = rt->rt_dst;
+ iph->saddr = rt->rt_src;
+
+ if ((iph->ttl = tiph->ttl) == 0) {
+ if (skb->protocol == __constant_htons(ETH_P_IP))
+ iph->ttl = old_iph->ttl;
+#ifdef CONFIG_IPV6
+ else if (skb->protocol == __constant_htons(ETH_P_IPV6))
+ iph->ttl = ((struct ipv6hdr*)old_iph)->hop_limit;
+#endif
+ else
+ iph->ttl = ip_statistics.IpDefaultTTL;
+ }
+
+ ((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));
+ }
+ }
+
+ iph->tot_len = htons(skb->len);
+ iph->id = htons(ip_id_count++);
+ ip_send_check(iph);
+
+ stats->tx_bytes += skb->len;
+ stats->tx_packets++;
+ ip_send(skb);
+ tunnel->recursion--;
+ return 0;
+
+tx_error_icmp:
+ if (skb->protocol == __constant_htons(ETH_P_IP))
+ icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
+#ifdef CONFIG_IPV6
+ else if (skb->protocol == __constant_htons(ETH_P_IPV6))
+ icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_ADDR_UNREACH, 0, dev);
+#endif
+
+tx_error:
+ stats->tx_errors++;
+ dev_kfree_skb(skb, FREE_WRITE);
+ tunnel->recursion--;
+ return 0;
+}
+
+static int
+ipgre_tunnel_ioctl (struct device *dev, struct ifreq *ifr, int cmd)
+{
+ int err = 0;
+ struct ip_tunnel_parm p;
+ struct ip_tunnel *t;
+
+ MOD_INC_USE_COUNT;
+
+ 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 = -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&__constant_htons(~IP_DF)) ||
+ ((p.i_flags|p.o_flags)&(GRE_VERSION|GRE_ROUTING)))
+ goto done;
+ if (p.iph.ttl)
+ p.iph.frag_off |= __constant_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 (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:
+ 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)
+ goto done;
+ }
+ err = unregister_netdevice(dev);
+ break;
+
+ default:
+ err = -EINVAL;
+ }
+
+done:
+ MOD_DEC_USE_COUNT;
+ return err;
+}
+
+static struct net_device_stats *ipgre_tunnel_get_stats(struct device *dev)
+{
+ return &(((struct ip_tunnel*)dev->priv)->stat);
+}
+
+static int ipgre_tunnel_change_mtu(struct 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 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_rebuild_header(struct sk_buff *skb)
+{
+ struct device *dev = skb->dev;
+ struct iphdr *iph = (struct iphdr *)skb->data;
+ u16 *p = (u16*)(iph + 1);
+ struct neighbour *neigh = NULL;
+
+ if (skb->dst)
+ neigh = skb->dst->neighbour;
+
+ if (neigh)
+ return neigh->ops->resolve((void*)&iph->daddr, skb);
+
+ if (p[1] == __constant_htons(ETH_P_IP))
+ return arp_find((void*)&iph->daddr, skb);
+
+ if (net_ratelimit())
+ printk(KERN_DEBUG "%s: unable to resolve type %X addresses.\n",
+ dev->name, (int)p[1]);
+ return 0;
+}
+
+static int ipgre_open(struct device *dev)
+{
+ struct ip_tunnel *t = (struct ip_tunnel*)dev->priv;
+
+ MOD_INC_USE_COUNT;
+ if (MULTICAST(t->parms.iph.daddr)) {
+ struct rtable *rt;
+ if (ip_route_output(&rt, t->parms.iph.daddr,
+ t->parms.iph.saddr, RT_TOS(t->parms.iph.tos),
+ t->parms.link)) {
+ MOD_DEC_USE_COUNT;
+ return -EADDRNOTAVAIL;
+ }
+ dev = rt->u.dst.dev;
+ ip_rt_put(rt);
+ if (dev->ip_ptr == NULL) {
+ MOD_DEC_USE_COUNT;
+ return -EADDRNOTAVAIL;
+ }
+ t->mlink = dev->ifindex;
+ ip_mc_inc_group(dev->ip_ptr, t->parms.iph.daddr);
+ }
+ return 0;
+}
+
+static int ipgre_close(struct device *dev)
+{
+ struct ip_tunnel *t = (struct ip_tunnel*)dev->priv;
+ if (MULTICAST(t->parms.iph.daddr) && t->mlink) {
+ dev = dev_get_by_index(t->mlink);
+ if (dev && dev->ip_ptr)
+ ip_mc_dec_group(dev->ip_ptr, t->parms.iph.daddr);
+ }
+ MOD_DEC_USE_COUNT;
+ return 0;
+}
+
+#endif
+
+static void ipgre_tunnel_init_gen(struct device *dev)
+{
+ struct ip_tunnel *t = (struct ip_tunnel*)dev->priv;
+
+ dev->destructor = ipgre_tunnel_destroy;
+ 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_init_buffers(dev);
+
+ 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;
+ memcpy(dev->dev_addr, &t->parms.iph.saddr, 4);
+ memcpy(dev->broadcast, &t->parms.iph.daddr, 4);
+}
+
+static int ipgre_tunnel_init(struct device *dev)
+{
+ struct 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;
+
+ ipgre_tunnel_init_gen(dev);
+
+ /* Guess output device to choose reasonable mtu and hard_header_len */
+
+ if (iph->daddr) {
+ struct rtable *rt;
+ if (!ip_route_output(&rt, iph->daddr, iph->saddr, RT_TOS(iph->tos), tunnel->parms.link)) {
+ 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->rebuild_header = ipgre_rebuild_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;
+}
+
+#ifdef MODULE
+static int ipgre_fb_tunnel_open(struct device *dev)
+{
+ MOD_INC_USE_COUNT;
+ return 0;
+}
+
+static int ipgre_fb_tunnel_close(struct device *dev)
+{
+ MOD_DEC_USE_COUNT;
+ return 0;
+}
+#endif
+
+__initfunc(int ipgre_fb_tunnel_init(struct device *dev))
+{
+ struct ip_tunnel *tunnel = (struct ip_tunnel*)dev->priv;
+ struct iphdr *iph;
+
+ ipgre_tunnel_init_gen(dev);
+#ifdef MODULE
+ dev->open = ipgre_fb_tunnel_open;
+ dev->stop = ipgre_fb_tunnel_close;
+#endif
+
+ iph = &ipgre_fb_tunnel.parms.iph;
+ iph->version = 4;
+ iph->protocol = IPPROTO_GRE;
+ iph->ihl = 5;
+ tunnel->hlen = sizeof(struct iphdr) + 4;
+
+ tunnels_wc[0] = &ipgre_fb_tunnel;
+ return 0;
+}
+
+
+static struct inet_protocol ipgre_protocol = {
+ ipgre_rcv, /* GRE handler */
+ ipgre_err, /* TUNNEL error control */
+ 0, /* next */
+ IPPROTO_GRE, /* protocol ID */
+ 0, /* copy */
+ NULL, /* data */
+ "GRE" /* name */
+};
+
+
+/*
+ * And now the modules code and kernel interface.
+ */
+
+#ifdef MODULE
+int init_module(void)
+#else
+__initfunc(int ipgre_init(void))
+#endif
+{
+ printk(KERN_INFO "GRE over IPv4 tunneling driver\n");
+
+ ipgre_fb_tunnel_dev.priv = (void*)&ipgre_fb_tunnel;
+ ipgre_fb_tunnel_dev.name = ipgre_fb_tunnel.parms.name;
+#ifdef MODULE
+ register_netdev(&ipgre_fb_tunnel_dev);
+#else
+ register_netdevice(&ipgre_fb_tunnel_dev);
+#endif
+
+ inet_add_protocol(&ipgre_protocol);
+ return 0;
+}
+
+#ifdef MODULE
+
+void cleanup_module(void)
+{
+ if ( inet_del_protocol(&ipgre_protocol) < 0 )
+ printk(KERN_INFO "ipgre close: can't remove protocol\n");
+
+ unregister_netdev(&ipgre_fb_tunnel_dev);
+}
+
+#endif
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TCL-scripts by Sam Shen, slshen@lbl.gov