2 * GRE over IPv4 demultiplexer driver
4 * Authors: Dmitry Kozlov (xeb@mail.ru)
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15 #include <linux/module.h>
17 #include <linux/icmp.h>
18 #include <linux/kernel.h>
19 #include <linux/kmod.h>
20 #include <linux/skbuff.h>
23 #include <linux/netdevice.h>
24 #include <linux/if_tunnel.h>
25 #include <linux/spinlock.h>
26 #include <net/protocol.h>
30 #include <net/route.h>
33 static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly;
34 static struct gre_cisco_protocol __rcu *gre_cisco_proto_list[GRE_IP_PROTO_MAX];
36 int gre_add_protocol(const struct gre_protocol *proto, u8 version)
38 if (version >= GREPROTO_MAX)
41 return (cmpxchg((const struct gre_protocol **)&gre_proto[version], NULL, proto) == NULL) ?
44 EXPORT_SYMBOL_GPL(gre_add_protocol);
46 int gre_del_protocol(const struct gre_protocol *proto, u8 version)
50 if (version >= GREPROTO_MAX)
53 ret = (cmpxchg((const struct gre_protocol **)&gre_proto[version], proto, NULL) == proto) ?
62 EXPORT_SYMBOL_GPL(gre_del_protocol);
64 void gre_build_header(struct sk_buff *skb, const struct tnl_ptk_info *tpi,
67 struct gre_base_hdr *greh;
69 skb_push(skb, hdr_len);
71 skb_reset_transport_header(skb);
72 greh = (struct gre_base_hdr *)skb->data;
73 greh->flags = tnl_flags_to_gre_flags(tpi->flags);
74 greh->protocol = tpi->proto;
76 if (tpi->flags&(TUNNEL_KEY|TUNNEL_CSUM|TUNNEL_SEQ)) {
77 __be32 *ptr = (__be32 *)(((u8 *)greh) + hdr_len - 4);
79 if (tpi->flags&TUNNEL_SEQ) {
83 if (tpi->flags&TUNNEL_KEY) {
87 if (tpi->flags&TUNNEL_CSUM &&
88 !(skb_shinfo(skb)->gso_type &
89 (SKB_GSO_GRE|SKB_GSO_GRE_CSUM))) {
91 *(__sum16 *)ptr = csum_fold(skb_checksum(skb, 0,
96 EXPORT_SYMBOL_GPL(gre_build_header);
98 static int parse_gre_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
101 const struct gre_base_hdr *greh;
105 if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr))))
108 greh = (struct gre_base_hdr *)skb_transport_header(skb);
109 if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING)))
112 tpi->flags = gre_flags_to_tnl_flags(greh->flags);
113 hdr_len = ip_gre_calc_hlen(tpi->flags);
115 if (!pskb_may_pull(skb, hdr_len))
118 greh = (struct gre_base_hdr *)skb_transport_header(skb);
119 tpi->proto = greh->protocol;
121 options = (__be32 *)(greh + 1);
122 if (greh->flags & GRE_CSUM) {
123 if (skb_checksum_simple_validate(skb)) {
128 skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
129 null_compute_pseudo);
134 if (greh->flags & GRE_KEY) {
140 if (unlikely(greh->flags & GRE_SEQ)) {
146 /* WCCP version 1 and 2 protocol decoding.
147 * - Change protocol to IP
148 * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
150 if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) {
151 tpi->proto = htons(ETH_P_IP);
152 if ((*(u8 *)options & 0xF0) != 0x40) {
154 if (!pskb_may_pull(skb, hdr_len))
159 return iptunnel_pull_header(skb, hdr_len, tpi->proto);
162 static int gre_cisco_rcv(struct sk_buff *skb)
164 struct tnl_ptk_info tpi;
166 bool csum_err = false;
168 #ifdef CONFIG_NET_IPGRE_BROADCAST
169 if (ipv4_is_multicast(ip_hdr(skb)->daddr)) {
170 /* Looped back packet, drop it! */
171 if (rt_is_output_route(skb_rtable(skb)))
176 if (parse_gre_header(skb, &tpi, &csum_err) < 0)
180 for (i = 0; i < GRE_IP_PROTO_MAX; i++) {
181 struct gre_cisco_protocol *proto;
184 proto = rcu_dereference(gre_cisco_proto_list[i]);
187 ret = proto->handler(skb, &tpi);
188 if (ret == PACKET_RCVD) {
195 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
201 static void gre_cisco_err(struct sk_buff *skb, u32 info)
203 /* All the routers (except for Linux) return only
204 * 8 bytes of packet payload. It means, that precise relaying of
205 * ICMP in the real Internet is absolutely infeasible.
207 * Moreover, Cisco "wise men" put GRE key to the third word
208 * in GRE header. It makes impossible maintaining even soft
210 * GRE tunnels with enabled checksum. Tell them "thank you".
212 * Well, I wonder, rfc1812 was written by Cisco employee,
213 * what the hell these idiots break standards established
217 const int type = icmp_hdr(skb)->type;
218 const int code = icmp_hdr(skb)->code;
219 struct tnl_ptk_info tpi;
220 bool csum_err = false;
223 if (parse_gre_header(skb, &tpi, &csum_err)) {
224 if (!csum_err) /* ignore csum errors. */
228 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
229 ipv4_update_pmtu(skb, dev_net(skb->dev), info,
230 skb->dev->ifindex, 0, IPPROTO_GRE, 0);
233 if (type == ICMP_REDIRECT) {
234 ipv4_redirect(skb, dev_net(skb->dev), skb->dev->ifindex, 0,
240 for (i = 0; i < GRE_IP_PROTO_MAX; i++) {
241 struct gre_cisco_protocol *proto;
243 proto = rcu_dereference(gre_cisco_proto_list[i]);
247 if (proto->err_handler(skb, info, &tpi) == PACKET_RCVD)
255 static int gre_rcv(struct sk_buff *skb)
257 const struct gre_protocol *proto;
261 if (!pskb_may_pull(skb, 12))
264 ver = skb->data[1]&0x7f;
265 if (ver >= GREPROTO_MAX)
269 proto = rcu_dereference(gre_proto[ver]);
270 if (!proto || !proto->handler)
272 ret = proto->handler(skb);
283 static void gre_err(struct sk_buff *skb, u32 info)
285 const struct gre_protocol *proto;
286 const struct iphdr *iph = (const struct iphdr *)skb->data;
287 u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f;
289 if (ver >= GREPROTO_MAX)
293 proto = rcu_dereference(gre_proto[ver]);
294 if (proto && proto->err_handler)
295 proto->err_handler(skb, info);
299 static const struct net_protocol net_gre_protocol = {
301 .err_handler = gre_err,
305 static const struct gre_protocol ipgre_protocol = {
306 .handler = gre_cisco_rcv,
307 .err_handler = gre_cisco_err,
310 int gre_cisco_register(struct gre_cisco_protocol *newp)
312 struct gre_cisco_protocol **proto = (struct gre_cisco_protocol **)
313 &gre_cisco_proto_list[newp->priority];
315 return (cmpxchg(proto, NULL, newp) == NULL) ? 0 : -EBUSY;
317 EXPORT_SYMBOL_GPL(gre_cisco_register);
319 int gre_cisco_unregister(struct gre_cisco_protocol *del_proto)
321 struct gre_cisco_protocol **proto = (struct gre_cisco_protocol **)
322 &gre_cisco_proto_list[del_proto->priority];
325 ret = (cmpxchg(proto, del_proto, NULL) == del_proto) ? 0 : -EINVAL;
333 EXPORT_SYMBOL_GPL(gre_cisco_unregister);
335 static int __init gre_init(void)
337 pr_info("GRE over IPv4 demultiplexor driver\n");
339 if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) {
340 pr_err("can't add protocol\n");
344 if (gre_add_protocol(&ipgre_protocol, GREPROTO_CISCO) < 0) {
345 pr_info("%s: can't add ipgre handler\n", __func__);
351 inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
356 static void __exit gre_exit(void)
358 gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO);
359 inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
362 module_init(gre_init);
363 module_exit(gre_exit);
365 MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver");
366 MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
367 MODULE_LICENSE("GPL");