net/ipv6/ipcomp6.c

   1 /*
   2  * IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173
   3  *
   4  * Copyright (C)2003 USAGI/WIDE Project
   5  *
   6  * Author       Mitsuru KANDA  <mk@linux-ipv6.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21  */
  22 /*
  23  * [Memo]
  24  *
  25  * Outbound:
  26  *  The compression of IP datagram MUST be done before AH/ESP processing,
  27  *  fragmentation, and the addition of Hop-by-Hop/Routing header.
  28  *
  29  * Inbound:
  30  *  The decompression of IP datagram MUST be done after the reassembly,
  31  *  AH/ESP processing.
  32  */
  33
  34 #define pr_fmt(fmt) "IPv6: " fmt
  35
  36 #include <linux/module.h>
  37 #include <net/ip.h>
  38 #include <net/xfrm.h>
  39 #include <net/ipcomp.h>
  40 #include <linux/crypto.h>
  41 #include <linux/err.h>
  42 #include <linux/pfkeyv2.h>
  43 #include <linux/random.h>
  44 #include <linux/percpu.h>
  45 #include <linux/smp.h>
  46 #include <linux/list.h>
  47 #include <linux/vmalloc.h>
  48 #include <linux/rtnetlink.h>
  49 #include <net/icmp.h>
  50 #include <net/ipv6.h>
  51 #include <net/protocol.h>
  52 #include <linux/ipv6.h>
  53 #include <linux/icmpv6.h>
  54 #include <linux/mutex.h>
  55
  56 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
  57                                 u8 type, u8 code, int offset, __be32 info)
  58 {
  59         struct net *net = dev_net(skb->dev);
  60         __be32 spi;
  61         const struct ipv6hdr *iph = (const struct ipv6hdr *)skb->data;
  62         struct ip_comp_hdr *ipcomph =
  63                 (struct ip_comp_hdr *)(skb->data + offset);
  64         struct xfrm_state *x;
  65
  66         if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG)
  67                 return;
  68
  69         spi = htonl(ntohs(ipcomph->cpi));
  70         x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
  71                               spi, IPPROTO_COMP, AF_INET6);
  72         if (!x)
  73                 return;
  74
  75         pr_debug("pmtu discovery on SA IPCOMP/%08x/%pI6\n",
  76                  spi, &iph->daddr);
  77         xfrm_state_put(x);
  78 }
  79
  80 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
  81 {
  82         struct net *net = xs_net(x);
  83         struct xfrm_state *t = NULL;
  84
  85         t = xfrm_state_alloc(net);
  86         if (!t)
  87                 goto out;
  88
  89         t->id.proto = IPPROTO_IPV6;
  90         t->id.spi = xfrm6_tunnel_alloc_spi(net, (xfrm_address_t *)&x->props.saddr);
  91         if (!t->id.spi)
  92                 goto error;
  93
  94         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
  95         memcpy(&t->sel, &x->sel, sizeof(t->sel));
  96         t->props.family = AF_INET6;
  97         t->props.mode = x->props.mode;
  98         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
  99         memcpy(&t->mark, &x->mark, sizeof(t->mark));
 100
 101         if (xfrm_init_state(t))
 102                 goto error;
 103
 104         atomic_set(&t->tunnel_users, 1);
 105
 106 out:
 107         return t;
 108
 109 error:
 110         t->km.state = XFRM_STATE_DEAD;
 111         xfrm_state_put(t);
 112         t = NULL;
 113         goto out;
 114 }
 115
 116 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
 117 {
 118         struct net *net = xs_net(x);
 119         int err = 0;
 120         struct xfrm_state *t = NULL;
 121         __be32 spi;
 122         u32 mark = x->mark.m & x->mark.v;
 123
 124         spi = xfrm6_tunnel_spi_lookup(net, (xfrm_address_t *)&x->props.saddr);
 125         if (spi)
 126                 t = xfrm_state_lookup(net, mark, (xfrm_address_t *)&x->id.daddr,
 127                                               spi, IPPROTO_IPV6, AF_INET6);
 128         if (!t) {
 129                 t = ipcomp6_tunnel_create(x);
 130                 if (!t) {
 131                         err = -EINVAL;
 132                         goto out;
 133                 }
 134                 xfrm_state_insert(t);
 135                 xfrm_state_hold(t);
 136         }
 137         x->tunnel = t;
 138         atomic_inc(&t->tunnel_users);
 139
 140 out:
 141         return err;
 142 }
 143
 144 static int ipcomp6_init_state(struct xfrm_state *x)
 145 {
 146         int err = -EINVAL;
 147
 148         x->props.header_len = 0;
 149         switch (x->props.mode) {
 150         case XFRM_MODE_TRANSPORT:
 151                 break;
 152         case XFRM_MODE_TUNNEL:
 153                 x->props.header_len += sizeof(struct ipv6hdr);
 154                 break;
 155         default:
 156                 goto out;
 157         }
 158
 159         err = ipcomp_init_state(x);
 160         if (err)
 161                 goto out;
 162
 163         if (x->props.mode == XFRM_MODE_TUNNEL) {
 164                 err = ipcomp6_tunnel_attach(x);
 165                 if (err)
 166                         goto out;
 167         }
 168
 169         err = 0;
 170 out:
 171         return err;
 172 }
 173
 174 static const struct xfrm_type ipcomp6_type =
 175 {
 176         .description    = "IPCOMP6",
 177         .owner          = THIS_MODULE,
 178         .proto          = IPPROTO_COMP,
 179         .init_state     = ipcomp6_init_state,
 180         .destructor     = ipcomp_destroy,
 181         .input          = ipcomp_input,
 182         .output         = ipcomp_output,
 183         .hdr_offset     = xfrm6_find_1stfragopt,
 184 };
 185
 186 static const struct inet6_protocol ipcomp6_protocol =
 187 {
 188         .handler        = xfrm6_rcv,
 189         .err_handler    = ipcomp6_err,
 190         .flags          = INET6_PROTO_NOPOLICY,
 191 };
 192
 193 static int __init ipcomp6_init(void)
 194 {
 195         if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
 196                 pr_info("%s: can't add xfrm type\n", __func__);
 197                 return -EAGAIN;
 198         }
 199         if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
 200                 pr_info("%s: can't add protocol\n", __func__);
 201                 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
 202                 return -EAGAIN;
 203         }
 204         return 0;
 205 }
 206
 207 static void __exit ipcomp6_fini(void)
 208 {
 209         if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0)
 210                 pr_info("%s: can't remove protocol\n", __func__);
 211         if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
 212                 pr_info("%s: can't remove xfrm type\n", __func__);
 213 }
 214
 215 module_init(ipcomp6_init);
 216 module_exit(ipcomp6_fini);
 217 MODULE_LICENSE("GPL");
 218 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
 219 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
 220
 221 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP);