544ce0876f12dcd78cfcf0d777e1b78bab5b4acf
[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         __be32 spi;
29         struct iphdr *iph = (struct iphdr *)skb->data;
30         struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
31         struct xfrm_state *x;
32
33         if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
34             icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
35                 return;
36
37         spi = htonl(ntohs(ipch->cpi));
38         x = xfrm_state_lookup(&init_net, (xfrm_address_t *)&iph->daddr,
39                               spi, IPPROTO_COMP, AF_INET);
40         if (!x)
41                 return;
42         NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%pI4\n",
43                  spi, &iph->daddr);
44         xfrm_state_put(x);
45 }
46
47 /* We always hold one tunnel user reference to indicate a tunnel */
48 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
49 {
50         struct xfrm_state *t;
51
52         t = xfrm_state_alloc(&init_net);
53         if (t == NULL)
54                 goto out;
55
56         t->id.proto = IPPROTO_IPIP;
57         t->id.spi = x->props.saddr.a4;
58         t->id.daddr.a4 = x->id.daddr.a4;
59         memcpy(&t->sel, &x->sel, sizeof(t->sel));
60         t->props.family = AF_INET;
61         t->props.mode = x->props.mode;
62         t->props.saddr.a4 = x->props.saddr.a4;
63         t->props.flags = x->props.flags;
64
65         if (xfrm_init_state(t))
66                 goto error;
67
68         atomic_set(&t->tunnel_users, 1);
69 out:
70         return t;
71
72 error:
73         t->km.state = XFRM_STATE_DEAD;
74         xfrm_state_put(t);
75         t = NULL;
76         goto out;
77 }
78
79 /*
80  * Must be protected by xfrm_cfg_mutex.  State and tunnel user references are
81  * always incremented on success.
82  */
83 static int ipcomp_tunnel_attach(struct xfrm_state *x)
84 {
85         int err = 0;
86         struct xfrm_state *t;
87
88         t = xfrm_state_lookup(&init_net, (xfrm_address_t *)&x->id.daddr.a4,
89                               x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
90         if (!t) {
91                 t = ipcomp_tunnel_create(x);
92                 if (!t) {
93                         err = -EINVAL;
94                         goto out;
95                 }
96                 xfrm_state_insert(t);
97                 xfrm_state_hold(t);
98         }
99         x->tunnel = t;
100         atomic_inc(&t->tunnel_users);
101 out:
102         return err;
103 }
104
105 static int ipcomp4_init_state(struct xfrm_state *x)
106 {
107         int err = -EINVAL;
108
109         x->props.header_len = 0;
110         switch (x->props.mode) {
111         case XFRM_MODE_TRANSPORT:
112                 break;
113         case XFRM_MODE_TUNNEL:
114                 x->props.header_len += sizeof(struct iphdr);
115                 break;
116         default:
117                 goto out;
118         }
119
120         err = ipcomp_init_state(x);
121         if (err)
122                 goto out;
123
124         if (x->props.mode == XFRM_MODE_TUNNEL) {
125                 err = ipcomp_tunnel_attach(x);
126                 if (err)
127                         goto out;
128         }
129
130         err = 0;
131 out:
132         return err;
133 }
134
135 static const struct xfrm_type ipcomp_type = {
136         .description    = "IPCOMP4",
137         .owner          = THIS_MODULE,
138         .proto          = IPPROTO_COMP,
139         .init_state     = ipcomp4_init_state,
140         .destructor     = ipcomp_destroy,
141         .input          = ipcomp_input,
142         .output         = ipcomp_output
143 };
144
145 static const struct net_protocol ipcomp4_protocol = {
146         .handler        =       xfrm4_rcv,
147         .err_handler    =       ipcomp4_err,
148         .no_policy      =       1,
149 };
150
151 static int __init ipcomp4_init(void)
152 {
153         if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
154                 printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
155                 return -EAGAIN;
156         }
157         if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
158                 printk(KERN_INFO "ipcomp init: can't add protocol\n");
159                 xfrm_unregister_type(&ipcomp_type, AF_INET);
160                 return -EAGAIN;
161         }
162         return 0;
163 }
164
165 static void __exit ipcomp4_fini(void)
166 {
167         if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
168                 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
169         if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
170                 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
171 }
172
173 module_init(ipcomp4_init);
174 module_exit(ipcomp4_fini);
175
176 MODULE_LICENSE("GPL");
177 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp/IPv4) - RFC3173");
178 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
179
180 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP);