linux/net/ipv4/ipcomp.c
<<
>>
Prefs
   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 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 */
  48static 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);
  69out:
  70        return t;
  71
  72error:
  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 */
  83static 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);
 101out:
 102        return err;
 103}
 104
 105static 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 error_tunnel;
 128        }
 129
 130        err = 0;
 131out:
 132        return err;
 133
 134error_tunnel:
 135        ipcomp_destroy(x);
 136        goto out;
 137}
 138
 139static const struct xfrm_type ipcomp_type = {
 140        .description    = "IPCOMP4",
 141        .owner          = THIS_MODULE,
 142        .proto          = IPPROTO_COMP,
 143        .init_state     = ipcomp4_init_state,
 144        .destructor     = ipcomp_destroy,
 145        .input          = ipcomp_input,
 146        .output         = ipcomp_output
 147};
 148
 149static struct net_protocol ipcomp4_protocol = {
 150        .handler        =       xfrm4_rcv,
 151        .err_handler    =       ipcomp4_err,
 152        .no_policy      =       1,
 153};
 154
 155static int __init ipcomp4_init(void)
 156{
 157        if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
 158                printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
 159                return -EAGAIN;
 160        }
 161        if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
 162                printk(KERN_INFO "ipcomp init: can't add protocol\n");
 163                xfrm_unregister_type(&ipcomp_type, AF_INET);
 164                return -EAGAIN;
 165        }
 166        return 0;
 167}
 168
 169static void __exit ipcomp4_fini(void)
 170{
 171        if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
 172                printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
 173        if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
 174                printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
 175}
 176
 177module_init(ipcomp4_init);
 178module_exit(ipcomp4_fini);
 179
 180MODULE_LICENSE("GPL");
 181MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp/IPv4) - RFC3173");
 182MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
 183
 184MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP);
 185