Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6
[linux-2.6.git] / net / ipv4 / ipcomp.c
1 /*
2  * IP Payload Compression Protocol (IPComp) - RFC3173.
3  *
4  * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License as published by the Free
8  * Software Foundation; either version 2 of the License, or (at your option)
9  * any later version.
10  *
11  * Todo:
12  *   - Tunable compression parameters.
13  *   - Compression stats.
14  *   - Adaptive compression.
15  */
16 #include <linux/module.h>
17 #include <linux/err.h>
18 #include <linux/rtnetlink.h>
19 #include <net/ip.h>
20 #include <net/xfrm.h>
21 #include <net/icmp.h>
22 #include <net/ipcomp.h>
23 #include <net/protocol.h>
24 #include <net/sock.h>
25
26 static void ipcomp4_err(struct sk_buff *skb, u32 info)
27 {
28         struct net *net = dev_net(skb->dev);
29         __be32 spi;
30         struct iphdr *iph = (struct iphdr *)skb->data;
31         struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
32         struct xfrm_state *x;
33
34         if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
35             icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
36                 return;
37
38         spi = htonl(ntohs(ipch->cpi));
39         x = xfrm_state_lookup(net, (xfrm_address_t *)&iph->daddr,
40                               spi, IPPROTO_COMP, AF_INET);
41         if (!x)
42                 return;
43         NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%pI4\n",
44                  spi, &iph->daddr);
45         xfrm_state_put(x);
46 }
47
48 /* We always hold one tunnel user reference to indicate a tunnel */
49 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
50 {
51         struct net *net = xs_net(x);
52         struct xfrm_state *t;
53
54         t = xfrm_state_alloc(net);
55         if (t == NULL)
56                 goto out;
57
58         t->id.proto = IPPROTO_IPIP;
59         t->id.spi = x->props.saddr.a4;
60         t->id.daddr.a4 = x->id.daddr.a4;
61         memcpy(&t->sel, &x->sel, sizeof(t->sel));
62         t->props.family = AF_INET;
63         t->props.mode = x->props.mode;
64         t->props.saddr.a4 = x->props.saddr.a4;
65         t->props.flags = x->props.flags;
66
67         if (xfrm_init_state(t))
68                 goto error;
69
70         atomic_set(&t->tunnel_users, 1);
71 out:
72         return t;
73
74 error:
75         t->km.state = XFRM_STATE_DEAD;
76         xfrm_state_put(t);
77         t = NULL;
78         goto out;
79 }
80
81 /*
82  * Must be protected by xfrm_cfg_mutex.  State and tunnel user references are
83  * always incremented on success.
84  */
85 static int ipcomp_tunnel_attach(struct xfrm_state *x)
86 {
87         struct net *net = xs_net(x);
88         int err = 0;
89         struct xfrm_state *t;
90
91         t = xfrm_state_lookup(net, (xfrm_address_t *)&x->id.daddr.a4,
92                               x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
93         if (!t) {
94                 t = ipcomp_tunnel_create(x);
95                 if (!t) {
96                         err = -EINVAL;
97                         goto out;
98                 }
99                 xfrm_state_insert(t);
100                 xfrm_state_hold(t);
101         }
102         x->tunnel = t;
103         atomic_inc(&t->tunnel_users);
104 out:
105         return err;
106 }
107
108 static int ipcomp4_init_state(struct xfrm_state *x)
109 {
110         int err = -EINVAL;
111
112         x->props.header_len = 0;
113         switch (x->props.mode) {
114         case XFRM_MODE_TRANSPORT:
115                 break;
116         case XFRM_MODE_TUNNEL:
117                 x->props.header_len += sizeof(struct iphdr);
118                 break;
119         default:
120                 goto out;
121         }
122
123         err = ipcomp_init_state(x);
124         if (err)
125                 goto out;
126
127         if (x->props.mode == XFRM_MODE_TUNNEL) {
128                 err = ipcomp_tunnel_attach(x);
129                 if (err)
130                         goto out;
131         }
132
133         err = 0;
134 out:
135         return err;
136 }
137
138 static const struct xfrm_type ipcomp_type = {
139         .description    = "IPCOMP4",
140         .owner          = THIS_MODULE,
141         .proto          = IPPROTO_COMP,
142         .init_state     = ipcomp4_init_state,
143         .destructor     = ipcomp_destroy,
144         .input          = ipcomp_input,
145         .output         = ipcomp_output
146 };
147
148 static const struct net_protocol ipcomp4_protocol = {
149         .handler        =       xfrm4_rcv,
150         .err_handler    =       ipcomp4_err,
151         .no_policy      =       1,
152 };
153
154 static int __init ipcomp4_init(void)
155 {
156         if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
157                 printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
158                 return -EAGAIN;
159         }
160         if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
161                 printk(KERN_INFO "ipcomp init: can't add protocol\n");
162                 xfrm_unregister_type(&ipcomp_type, AF_INET);
163                 return -EAGAIN;
164         }
165         return 0;
166 }
167
168 static void __exit ipcomp4_fini(void)
169 {
170         if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
171                 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
172         if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
173                 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
174 }
175
176 module_init(ipcomp4_init);
177 module_exit(ipcomp4_fini);
178
179 MODULE_LICENSE("GPL");
180 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp/IPv4) - RFC3173");
181 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
182
183 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP);