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 #include <linux/module.h>
14 #include <linux/kernel.h>
15 #include <linux/kmod.h>
16 #include <linux/skbuff.h>
19 #include <linux/netdevice.h>
20 #include <linux/version.h>
21 #include <linux/spinlock.h>
22 #include <net/protocol.h>
26 static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly;
27 static DEFINE_SPINLOCK(gre_proto_lock);
29 int gre_add_protocol(const struct gre_protocol *proto, u8 version)
31 if (version >= GREPROTO_MAX)
34 spin_lock(&gre_proto_lock);
35 if (gre_proto[version])
38 rcu_assign_pointer(gre_proto[version], proto);
39 spin_unlock(&gre_proto_lock);
43 spin_unlock(&gre_proto_lock);
47 EXPORT_SYMBOL_GPL(gre_add_protocol);
49 int gre_del_protocol(const struct gre_protocol *proto, u8 version)
51 if (version >= GREPROTO_MAX)
54 spin_lock(&gre_proto_lock);
55 if (rcu_dereference_protected(gre_proto[version],
56 lockdep_is_held(&gre_proto_lock)) != proto)
58 rcu_assign_pointer(gre_proto[version], NULL);
59 spin_unlock(&gre_proto_lock);
64 spin_unlock(&gre_proto_lock);
68 EXPORT_SYMBOL_GPL(gre_del_protocol);
70 static int gre_rcv(struct sk_buff *skb)
72 const struct gre_protocol *proto;
76 if (!pskb_may_pull(skb, 12))
79 ver = skb->data[1]&0x7f;
80 if (ver >= GREPROTO_MAX)
84 proto = rcu_dereference(gre_proto[ver]);
85 if (!proto || !proto->handler)
87 ret = proto->handler(skb);
98 static void gre_err(struct sk_buff *skb, u32 info)
100 const struct gre_protocol *proto;
101 const struct iphdr *iph = (const struct iphdr *)skb->data;
102 u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f;
104 if (ver >= GREPROTO_MAX)
108 proto = rcu_dereference(gre_proto[ver]);
109 if (proto && proto->err_handler)
110 proto->err_handler(skb, info);
114 static const struct net_protocol net_gre_protocol = {
116 .err_handler = gre_err,
120 static int __init gre_init(void)
122 pr_info("GRE over IPv4 demultiplexor driver");
124 if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) {
125 pr_err("gre: can't add protocol\n");
132 static void __exit gre_exit(void)
134 inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
137 module_init(gre_init);
138 module_exit(gre_exit);
140 MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver");
141 MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
142 MODULE_LICENSE("GPL");