Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec
[~shefty/rdma-dev.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         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;
38         case ICMP_REDIRECT:
39                 break;
40         default:
41                 return;
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;
49
50         if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH) {
51                 atomic_inc(&flow_cache_genid);
52                 rt_genid_bump(net);
53
54                 ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_COMP, 0);
55         } else
56                 ipv4_redirect(skb, net, 0, 0, IPPROTO_COMP, 0);
57         xfrm_state_put(x);
58 }
59
60 /* We always hold one tunnel user reference to indicate a tunnel */
61 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
62 {
63         struct net *net = xs_net(x);
64         struct xfrm_state *t;
65
66         t = xfrm_state_alloc(net);
67         if (t == NULL)
68                 goto out;
69
70         t->id.proto = IPPROTO_IPIP;
71         t->id.spi = x->props.saddr.a4;
72         t->id.daddr.a4 = x->id.daddr.a4;
73         memcpy(&t->sel, &x->sel, sizeof(t->sel));
74         t->props.family = AF_INET;
75         t->props.mode = x->props.mode;
76         t->props.saddr.a4 = x->props.saddr.a4;
77         t->props.flags = x->props.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);
84 out:
85         return t;
86
87 error:
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  */
98 static 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);
118 out:
119         return err;
120 }
121
122 static 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;
148 out:
149         return err;
150 }
151
152 static const struct xfrm_type ipcomp_type = {
153         .description    = "IPCOMP4",
154         .owner          = THIS_MODULE,
155         .proto          = IPPROTO_COMP,
156         .init_state     = ipcomp4_init_state,
157         .destructor     = ipcomp_destroy,
158         .input          = ipcomp_input,
159         .output         = ipcomp_output
160 };
161
162 static const struct net_protocol ipcomp4_protocol = {
163         .handler        =       xfrm4_rcv,
164         .err_handler    =       ipcomp4_err,
165         .no_policy      =       1,
166 };
167
168 static int __init ipcomp4_init(void)
169 {
170         if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
171                 pr_info("%s: can't add xfrm type\n", __func__);
172                 return -EAGAIN;
173         }
174         if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
175                 pr_info("%s: can't add protocol\n", __func__);
176                 xfrm_unregister_type(&ipcomp_type, AF_INET);
177                 return -EAGAIN;
178         }
179         return 0;
180 }
181
182 static void __exit ipcomp4_fini(void)
183 {
184         if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
185                 pr_info("%s: can't remove protocol\n", __func__);
186         if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
187                 pr_info("%s: can't remove xfrm type\n", __func__);
188 }
189
190 module_init(ipcomp4_init);
191 module_exit(ipcomp4_fini);
192
193 MODULE_LICENSE("GPL");
194 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp/IPv4) - RFC3173");
195 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
196
197 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP);