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Linux/net/ipv4/ipcomp.c

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  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 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, 0, IPPROTO_COMP, 0);
 52         else
 53                 ipv4_redirect(skb, net, 0, 0, IPPROTO_COMP, 0);
 54         xfrm_state_put(x);
 55 
 56         return 0;
 57 }
 58 
 59 /* We always hold one tunnel user reference to indicate a tunnel */
 60 static 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);
 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 int ipcomp4_rcv_cb(struct sk_buff *skb, int err)
153 {
154         return 0;
155 }
156 
157 static 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 
167 static 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 
175 static 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 
189 static 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 
197 module_init(ipcomp4_init);
198 module_exit(ipcomp4_fini);
199 
200 MODULE_LICENSE("GPL");
201 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp/IPv4) - RFC3173");
202 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
203 
204 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP);
205 

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