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
26static int ipcomp4_err(struct sk_buff *skb, u32 info)
27{
28 struct net *net = dev_net(skb->dev);
29 __be32 spi;
30 const struct iphdr *iph = (const 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 switch (icmp_hdr(skb)->type) {
35 case ICMP_DEST_UNREACH:
36 if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
37 return 0;
38 case ICMP_REDIRECT:
39 break;
40 default:
41 return 0;
42 }
43
44 spi = htonl(ntohs(ipch->cpi));
45 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
46 spi, IPPROTO_COMP, AF_INET);
47 if (!x)
48 return 0;
49
50 if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH)
51 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_COMP);
52 else
53 ipv4_redirect(skb, net, 0, IPPROTO_COMP);
54 xfrm_state_put(x);
55
56 return 0;
57}
58
59/* We always hold one tunnel user reference to indicate a tunnel */
60static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
61{
62 struct net *net = xs_net(x);
63 struct xfrm_state *t;
64
65 t = xfrm_state_alloc(net);
66 if (!t)
67 goto out;
68
69 t->id.proto = IPPROTO_IPIP;
70 t->id.spi = x->props.saddr.a4;
71 t->id.daddr.a4 = x->id.daddr.a4;
72 memcpy(&t->sel, &x->sel, sizeof(t->sel));
73 t->props.family = AF_INET;
74 t->props.mode = x->props.mode;
75 t->props.saddr.a4 = x->props.saddr.a4;
76 t->props.flags = x->props.flags;
77 t->props.extra_flags = x->props.extra_flags;
78 memcpy(&t->mark, &x->mark, sizeof(t->mark));
79
80 if (xfrm_init_state(t))
81 goto error;
82
83 atomic_set(&t->tunnel_users, 1);
84out:
85 return t;
86
87error:
88 t->km.state = XFRM_STATE_DEAD;
89 xfrm_state_put(t);
90 t = NULL;
91 goto out;
92}
93
94/*
95 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are
96 * always incremented on success.
97 */
98static int ipcomp_tunnel_attach(struct xfrm_state *x)
99{
100 struct net *net = xs_net(x);
101 int err = 0;
102 struct xfrm_state *t;
103 u32 mark = x->mark.v & x->mark.m;
104
105 t = xfrm_state_lookup(net, mark, (xfrm_address_t *)&x->id.daddr.a4,
106 x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
107 if (!t) {
108 t = ipcomp_tunnel_create(x);
109 if (!t) {
110 err = -EINVAL;
111 goto out;
112 }
113 xfrm_state_insert(t);
114 xfrm_state_hold(t);
115 }
116 x->tunnel = t;
117 atomic_inc(&t->tunnel_users);
118out:
119 return err;
120}
121
122static int ipcomp4_init_state(struct xfrm_state *x)
123{
124 int err = -EINVAL;
125
126 x->props.header_len = 0;
127 switch (x->props.mode) {
128 case XFRM_MODE_TRANSPORT:
129 break;
130 case XFRM_MODE_TUNNEL:
131 x->props.header_len += sizeof(struct iphdr);
132 break;
133 default:
134 goto out;
135 }
136
137 err = ipcomp_init_state(x);
138 if (err)
139 goto out;
140
141 if (x->props.mode == XFRM_MODE_TUNNEL) {
142 err = ipcomp_tunnel_attach(x);
143 if (err)
144 goto out;
145 }
146
147 err = 0;
148out:
149 return err;
150}
151
152static int ipcomp4_rcv_cb(struct sk_buff *skb, int err)
153{
154 return 0;
155}
156
157static const struct xfrm_type ipcomp_type = {
158 .description = "IPCOMP4",
159 .owner = THIS_MODULE,
160 .proto = IPPROTO_COMP,
161 .init_state = ipcomp4_init_state,
162 .destructor = ipcomp_destroy,
163 .input = ipcomp_input,
164 .output = ipcomp_output
165};
166
167static struct xfrm4_protocol ipcomp4_protocol = {
168 .handler = xfrm4_rcv,
169 .input_handler = xfrm_input,
170 .cb_handler = ipcomp4_rcv_cb,
171 .err_handler = ipcomp4_err,
172 .priority = 0,
173};
174
175static int __init ipcomp4_init(void)
176{
177 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
178 pr_info("%s: can't add xfrm type\n", __func__);
179 return -EAGAIN;
180 }
181 if (xfrm4_protocol_register(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
182 pr_info("%s: can't add protocol\n", __func__);
183 xfrm_unregister_type(&ipcomp_type, AF_INET);
184 return -EAGAIN;
185 }
186 return 0;
187}
188
189static void __exit ipcomp4_fini(void)
190{
191 if (xfrm4_protocol_deregister(&ipcomp4_protocol, IPPROTO_COMP) < 0)
192 pr_info("%s: can't remove protocol\n", __func__);
193 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
194 pr_info("%s: can't remove xfrm type\n", __func__);
195}
196
197module_init(ipcomp4_init);
198module_exit(ipcomp4_fini);
199
200MODULE_LICENSE("GPL");
201MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp/IPv4) - RFC3173");
202MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
203
204MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP);
205