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>
16 #include <linux/kernel.h>
17 #include <linux/kmod.h>
18 #include <linux/skbuff.h>
21 #include <linux/netdevice.h>
22 #include <linux/if_tunnel.h>
23 #include <linux/spinlock.h>
24 #include <net/protocol.h>
28 static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly;
30 int gre_add_protocol(const struct gre_protocol *proto, u8 version)
32 if (version >= GREPROTO_MAX)
35 return (cmpxchg((const struct gre_protocol **)&gre_proto[version], NULL, proto) == NULL) ?
38 EXPORT_SYMBOL_GPL(gre_add_protocol);
40 int gre_del_protocol(const struct gre_protocol *proto, u8 version)
44 if (version >= GREPROTO_MAX)
47 ret = (cmpxchg((const struct gre_protocol **)&gre_proto[version], proto, NULL) == proto) ?
56 EXPORT_SYMBOL_GPL(gre_del_protocol);
58 static int gre_rcv(struct sk_buff *skb)
60 const struct gre_protocol *proto;
64 if (!pskb_may_pull(skb, 12))
67 ver = skb->data[1]&0x7f;
68 if (ver >= GREPROTO_MAX)
72 proto = rcu_dereference(gre_proto[ver]);
73 if (!proto || !proto->handler)
75 ret = proto->handler(skb);
86 static void gre_err(struct sk_buff *skb, u32 info)
88 const struct gre_protocol *proto;
89 const struct iphdr *iph = (const struct iphdr *)skb->data;
90 u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f;
92 if (ver >= GREPROTO_MAX)
96 proto = rcu_dereference(gre_proto[ver]);
97 if (proto && proto->err_handler)
98 proto->err_handler(skb, info);
102 static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
103 netdev_features_t features)
105 struct sk_buff *segs = ERR_PTR(-EINVAL);
106 netdev_features_t enc_features;
107 int ghl = GRE_HEADER_SECTION;
108 struct gre_base_hdr *greh;
109 int mac_len = skb->mac_len;
110 __be16 protocol = skb->protocol;
114 if (unlikely(skb_shinfo(skb)->gso_type &
123 if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
126 greh = (struct gre_base_hdr *)skb_transport_header(skb);
128 if (greh->flags & GRE_KEY)
129 ghl += GRE_HEADER_SECTION;
130 if (greh->flags & GRE_SEQ)
131 ghl += GRE_HEADER_SECTION;
132 if (greh->flags & GRE_CSUM) {
133 ghl += GRE_HEADER_SECTION;
138 /* setup inner skb. */
139 skb->protocol = greh->protocol;
140 skb->encapsulation = 0;
142 if (unlikely(!pskb_may_pull(skb, ghl)))
144 __skb_pull(skb, ghl);
145 skb_reset_mac_header(skb);
146 skb_set_network_header(skb, skb_inner_network_offset(skb));
147 skb->mac_len = skb_inner_network_offset(skb);
149 /* segment inner packet. */
150 enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
151 segs = skb_mac_gso_segment(skb, enc_features);
152 if (!segs || IS_ERR(segs))
156 tnl_hlen = skb_tnl_header_len(skb);
158 __skb_push(skb, ghl);
162 if (skb_has_shared_frag(skb)) {
165 err = __skb_linearize(skb);
173 greh = (struct gre_base_hdr *)(skb->data);
174 pcsum = (__be32 *)(greh + 1);
176 *(__sum16 *)pcsum = csum_fold(skb_checksum(skb, 0, skb->len, 0));
178 __skb_push(skb, tnl_hlen - ghl);
180 skb_reset_mac_header(skb);
181 skb_set_network_header(skb, mac_len);
182 skb->mac_len = mac_len;
183 skb->protocol = protocol;
184 } while ((skb = skb->next));
189 static int gre_gso_send_check(struct sk_buff *skb)
191 if (!skb->encapsulation)
196 static const struct net_protocol net_gre_protocol = {
198 .err_handler = gre_err,
202 static const struct net_offload gre_offload = {
204 .gso_send_check = gre_gso_send_check,
205 .gso_segment = gre_gso_segment,
209 static int __init gre_init(void)
211 pr_info("GRE over IPv4 demultiplexor driver\n");
213 if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) {
214 pr_err("can't add protocol\n");
218 if (inet_add_offload(&gre_offload, IPPROTO_GRE)) {
219 pr_err("can't add protocol offload\n");
220 inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
227 static void __exit gre_exit(void)
229 inet_del_offload(&gre_offload, IPPROTO_GRE);
230 inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
233 module_init(gre_init);
234 module_exit(gre_exit);
236 MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver");
237 MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
238 MODULE_LICENSE("GPL");