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;
35 int gre_add_protocol(const struct gre_protocol *proto, u8 version)
37 if (version >= GREPROTO_MAX)
40 return (cmpxchg((const struct gre_protocol **)&gre_proto[version], NULL, proto) == NULL) ?
43 EXPORT_SYMBOL_GPL(gre_add_protocol);
45 int gre_del_protocol(const struct gre_protocol *proto, u8 version)
49 if (version >= GREPROTO_MAX)
52 ret = (cmpxchg((const struct gre_protocol **)&gre_proto[version], proto, NULL) == proto) ?
61 EXPORT_SYMBOL_GPL(gre_del_protocol);
63 int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
64 bool *csum_err, int *ret_hdr_len)
66 const struct gre_base_hdr *greh;
70 if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr))))
73 greh = (struct gre_base_hdr *)skb_transport_header(skb);
74 if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING)))
77 tpi->flags = gre_flags_to_tnl_flags(greh->flags);
78 hdr_len = gre_calc_hlen(tpi->flags);
80 if (!pskb_may_pull(skb, hdr_len))
83 greh = (struct gre_base_hdr *)skb_transport_header(skb);
84 tpi->proto = greh->protocol;
86 options = (__be32 *)(greh + 1);
87 if (greh->flags & GRE_CSUM) {
88 if (skb_checksum_simple_validate(skb)) {
93 skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
98 if (greh->flags & GRE_KEY) {
104 if (unlikely(greh->flags & GRE_SEQ)) {
110 /* WCCP version 1 and 2 protocol decoding.
111 * - Change protocol to IP
112 * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
114 if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) {
115 tpi->proto = htons(ETH_P_IP);
116 if ((*(u8 *)options & 0xF0) != 0x40) {
118 if (!pskb_may_pull(skb, hdr_len))
122 *ret_hdr_len = hdr_len;
125 EXPORT_SYMBOL(gre_parse_header);
127 static int gre_rcv(struct sk_buff *skb)
129 const struct gre_protocol *proto;
133 if (!pskb_may_pull(skb, 12))
136 ver = skb->data[1]&0x7f;
137 if (ver >= GREPROTO_MAX)
141 proto = rcu_dereference(gre_proto[ver]);
142 if (!proto || !proto->handler)
144 ret = proto->handler(skb);
155 static void gre_err(struct sk_buff *skb, u32 info)
157 const struct gre_protocol *proto;
158 const struct iphdr *iph = (const struct iphdr *)skb->data;
159 u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f;
161 if (ver >= GREPROTO_MAX)
165 proto = rcu_dereference(gre_proto[ver]);
166 if (proto && proto->err_handler)
167 proto->err_handler(skb, info);
171 static const struct net_protocol net_gre_protocol = {
173 .err_handler = gre_err,
177 static int __init gre_init(void)
179 pr_info("GRE over IPv4 demultiplexor driver\n");
181 if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) {
182 pr_err("can't add protocol\n");
188 static void __exit gre_exit(void)
190 inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
193 module_init(gre_init);
194 module_exit(gre_exit);
196 MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver");
197 MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
198 MODULE_LICENSE("GPL");