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 #include <linux/config.h>
  34 #include <linux/module.h>
  35 #include <net/inet_ecn.h>
  36 #include <net/ip.h>
  37 #include <net/xfrm.h>
  38 #include <net/ipcomp.h>
  39 #include <asm/scatterlist.h>
  40 #include <linux/crypto.h>
  41 #include <linux/pfkeyv2.h>
  42 #include <linux/random.h>
  43 #include <net/icmp.h>
  44 #include <net/ipv6.h>
  45 #include <linux/ipv6.h>
  46 #include <linux/icmpv6.h>
  47
  48 static int ipcomp6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb)
  49 {
  50         int err = 0;
  51         u8 nexthdr = 0;
  52         u8 *prevhdr;
  53         int hdr_len = skb->h.raw - skb->nh.raw;
  54         unsigned char *tmp_hdr = NULL;
  55         struct ipv6hdr *iph;
  56         int plen, dlen;
  57         struct ipcomp_data *ipcd = x->data;
  58         u8 *start, *scratch = ipcd->scratch;
  59
  60         if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
  61                 skb_linearize(skb, GFP_ATOMIC) != 0) {
  62                 err = -ENOMEM;
  63                 goto out;
  64         }
  65
  66         skb->ip_summed = CHECKSUM_NONE;
  67
  68         /* Remove ipcomp header and decompress original payload */
  69         iph = skb->nh.ipv6h;
  70         tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC);
  71         if (!tmp_hdr)
  72                 goto out;
  73         memcpy(tmp_hdr, iph, hdr_len);
  74         nexthdr = *(u8 *)skb->data;
  75         skb_pull(skb, sizeof(struct ipv6_comp_hdr));
  76         skb->nh.raw += sizeof(struct ipv6_comp_hdr);
  77         memcpy(skb->nh.raw, tmp_hdr, hdr_len);
  78         iph = skb->nh.ipv6h;
  79         iph->payload_len = htons(ntohs(iph->payload_len) - sizeof(struct ipv6_comp_hdr));
  80         skb->h.raw = skb->data;
  81
  82         /* decompression */
  83         plen = skb->len;
  84         dlen = IPCOMP_SCRATCH_SIZE;
  85         start = skb->data;
  86
  87         err = crypto_comp_decompress(ipcd->tfm, start, plen, scratch, &dlen);
  88         if (err) {
  89                 err = -EINVAL;
  90                 goto out;
  91         }
  92
  93         if (dlen < (plen + sizeof(struct ipv6_comp_hdr))) {
  94                 err = -EINVAL;
  95                 goto out;
  96         }
  97
  98         err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
  99         if (err) {
 100                 goto out;
 101         }
 102
 103         skb_put(skb, dlen - plen);
 104         memcpy(skb->data, scratch, dlen);
 105
 106         iph = skb->nh.ipv6h;
 107         iph->payload_len = htons(skb->len);
 108
 109         ip6_find_1stfragopt(skb, &prevhdr);
 110         *prevhdr = nexthdr;
 111 out:
 112         if (tmp_hdr)
 113                 kfree(tmp_hdr);
 114         if (err)
 115                 goto error_out;
 116         return nexthdr;
 117 error_out:
 118         return err;
 119 }
 120
 121 static int ipcomp6_output(struct sk_buff **pskb)
 122 {
 123         int err;
 124         struct dst_entry *dst = (*pskb)->dst;
 125         struct xfrm_state *x = dst->xfrm;
 126         struct ipv6hdr *iph, *top_iph;
 127         int hdr_len = 0;
 128         struct ipv6_comp_hdr *ipch;
 129         struct ipcomp_data *ipcd = x->data;
 130         u8 *prevhdr;
 131         u8 nexthdr = 0;
 132         int plen, dlen;
 133         u8 *start, *scratch = ipcd->scratch;
 134
 135         if ((*pskb)->ip_summed == CHECKSUM_HW) {
 136                 err = skb_checksum_help(pskb, 0);
 137                 if (err)
 138                         goto error_nolock;
 139         }
 140
 141         spin_lock_bh(&x->lock);
 142
 143         err = xfrm_state_check(x, *pskb);
 144         if (err)
 145                 goto error;
 146
 147         if (x->props.mode) {
 148                 err = xfrm6_tunnel_check_size(*pskb);
 149                 if (err)
 150                         goto error;
 151
 152                 hdr_len = sizeof(struct ipv6hdr);
 153                 nexthdr = IPPROTO_IPV6;
 154                 iph = (*pskb)->nh.ipv6h;
 155                 top_iph = (struct ipv6hdr *)skb_push(*pskb, sizeof(struct ipv6hdr));
 156                 top_iph->version = 6;
 157                 top_iph->priority = iph->priority;
 158                 top_iph->flow_lbl[0] = iph->flow_lbl[0];
 159                 top_iph->flow_lbl[1] = iph->flow_lbl[1];
 160                 top_iph->flow_lbl[2] = iph->flow_lbl[2];
 161                 top_iph->nexthdr = IPPROTO_IPV6; /* initial */
 162                 top_iph->payload_len = htons((*pskb)->len - sizeof(struct ipv6hdr));
 163                 top_iph->hop_limit = iph->hop_limit;
 164                 memcpy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr, sizeof(struct in6_addr));
 165                 memcpy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr, sizeof(struct in6_addr));
 166                 (*pskb)->nh.raw = (*pskb)->data; /* == top_iph */
 167                 (*pskb)->h.raw = (*pskb)->nh.raw + hdr_len;
 168         } else {
 169                 hdr_len = ip6_find_1stfragopt(*pskb, &prevhdr);
 170                 nexthdr = *prevhdr;
 171         }
 172
 173         /* check whether datagram len is larger than threshold */
 174         if (((*pskb)->len - hdr_len) < ipcd->threshold) {
 175                 goto out_ok;
 176         }
 177
 178         if ((skb_is_nonlinear(*pskb) || skb_cloned(*pskb)) &&
 179                 skb_linearize(*pskb, GFP_ATOMIC) != 0) {
 180                 err = -ENOMEM;
 181                 goto error;
 182         }
 183
 184         /* compression */
 185         plen = (*pskb)->len - hdr_len;
 186         dlen = IPCOMP_SCRATCH_SIZE;
 187         start = (*pskb)->data + hdr_len;
 188
 189         err = crypto_comp_compress(ipcd->tfm, start, plen, scratch, &dlen);
 190         if (err) {
 191                 goto error;
 192         }
 193         if ((dlen + sizeof(struct ipv6_comp_hdr)) >= plen) {
 194                 goto out_ok;
 195         }
 196         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
 197         pskb_trim(*pskb, hdr_len + dlen + sizeof(struct ip_comp_hdr));
 198
 199         /* insert ipcomp header and replace datagram */
 200         top_iph = (*pskb)->nh.ipv6h;
 201
 202         if (x->props.mode && (x->props.flags & XFRM_STATE_NOECN))
 203                 IP6_ECN_clear(top_iph);
 204         top_iph->payload_len = htons((*pskb)->len - sizeof(struct ipv6hdr));
 205         (*pskb)->nh.raw = (*pskb)->data; /* top_iph */
 206         ip6_find_1stfragopt(*pskb, &prevhdr);
 207         *prevhdr = IPPROTO_COMP;
 208
 209         ipch = (struct ipv6_comp_hdr *)((unsigned char *)top_iph + hdr_len);
 210         ipch->nexthdr = nexthdr;
 211         ipch->flags = 0;
 212         ipch->cpi = htons((u16 )ntohl(x->id.spi));
 213
 214         (*pskb)->h.raw = (unsigned char*)ipch;
 215 out_ok:
 216         x->curlft.bytes += (*pskb)->len;
 217         x->curlft.packets++;
 218         spin_unlock_bh(&x->lock);
 219
 220         if (((*pskb)->dst = dst_pop(dst)) == NULL) {
 221                 err = -EHOSTUNREACH;
 222                 goto error_nolock;
 223         }
 224         err = NET_XMIT_BYPASS;
 225
 226 out_exit:
 227         return err;
 228 error:
 229         spin_unlock_bh(&x->lock);
 230 error_nolock:
 231         kfree_skb(*pskb);
 232         goto out_exit;
 233 }
 234
 235 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 236                                 int type, int code, int offset, __u32 info)
 237 {
 238         u32 spi;
 239         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 240         struct ipv6_comp_hdr *ipcomph = (struct ipv6_comp_hdr*)(skb->data+offset);
 241         struct xfrm_state *x;
 242
 243         if (type != ICMPV6_DEST_UNREACH || type != ICMPV6_PKT_TOOBIG)
 244                 return;
 245
 246         spi = ntohl(ntohs(ipcomph->cpi));
 247         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6);
 248         if (!x)
 249                 return;
 250
 251         printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/"
 252                         "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n",
 253                         spi, NIP6(iph->daddr));
 254         xfrm_state_put(x);
 255 }
 256
 257 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
 258 {
 259         struct xfrm_state *t = NULL;
 260
 261         t = xfrm_state_alloc();
 262         if (!t)
 263                 goto out;
 264
 265         t->id.proto = IPPROTO_IPV6;
 266         t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);
 267         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
 268         memcpy(&t->sel, &x->sel, sizeof(t->sel));
 269         t->props.family = AF_INET6;
 270         t->props.mode = 1;
 271         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
 272
 273         t->type = xfrm_get_type(IPPROTO_IPV6, t->props.family);
 274         if (t->type == NULL)
 275                 goto error;
 276
 277         if (t->type->init_state(t, NULL))
 278                 goto error;
 279
 280         t->km.state = XFRM_STATE_VALID;
 281         atomic_set(&t->tunnel_users, 1);
 282
 283 out:
 284         return t;
 285
 286 error:
 287         xfrm_state_put(t);
 288         goto out;
 289 }
 290
 291 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
 292 {
 293         int err = 0;
 294         struct xfrm_state *t = NULL;
 295         u32 spi;
 296
 297         spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
 298         if (spi)
 299                 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
 300                                               spi, IPPROTO_IPV6, AF_INET6);
 301         if (!t) {
 302                 t = ipcomp6_tunnel_create(x);
 303                 if (!t) {
 304                         err = -EINVAL;
 305                         goto out;
 306                 }
 307                 xfrm_state_insert(t);
 308                 xfrm_state_hold(t);
 309         }
 310         x->tunnel = t;
 311         atomic_inc(&t->tunnel_users);
 312
 313 out:
 314         return err;
 315 }
 316
 317 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
 318 {
 319         if (ipcd->tfm)
 320                 crypto_free_tfm(ipcd->tfm);
 321         if (ipcd->scratch)
 322                 kfree(ipcd->scratch);
 323 }
 324
 325 static void ipcomp6_destroy(struct xfrm_state *x)
 326 {
 327         struct ipcomp_data *ipcd = x->data;
 328         if (!ipcd)
 329                 return;
 330         xfrm_state_delete_tunnel(x);
 331         ipcomp6_free_data(ipcd);
 332         kfree(ipcd);
 333
 334         xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
 335 }
 336
 337 static int ipcomp6_init_state(struct xfrm_state *x, void *args)
 338 {
 339         int err;
 340         struct ipcomp_data *ipcd;
 341         struct xfrm_algo_desc *calg_desc;
 342
 343         err = -EINVAL;
 344         if (!x->calg)
 345                 goto out;
 346
 347         err = -ENOMEM;
 348         ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL);
 349         if (!ipcd)
 350                 goto error;
 351
 352         memset(ipcd, 0, sizeof(*ipcd));
 353         x->props.header_len = 0;
 354         if (x->props.mode)
 355                 x->props.header_len += sizeof(struct ipv6hdr);
 356
 357         ipcd->scratch = kmalloc(IPCOMP_SCRATCH_SIZE, GFP_KERNEL);
 358         if (!ipcd->scratch)
 359                 goto error;
 360
 361         ipcd->tfm = crypto_alloc_tfm(x->calg->alg_name, 0);
 362         if (!ipcd->tfm)
 363                 goto error;
 364
 365         if (x->props.mode) {
 366                 err = ipcomp6_tunnel_attach(x);
 367                 if (err)
 368                         goto error;
 369         }
 370
 371         calg_desc = xfrm_calg_get_byname(x->calg->alg_name);
 372         BUG_ON(!calg_desc);
 373         ipcd->threshold = calg_desc->uinfo.comp.threshold;
 374         x->data = ipcd;
 375         err = 0;
 376 out:
 377         return err;
 378 error:
 379         if (ipcd) {
 380                 ipcomp6_free_data(ipcd);
 381                 kfree(ipcd);
 382         }
 383
 384         goto out;
 385 }
 386
 387 static struct xfrm_type ipcomp6_type =
 388 {
 389         .description    = "IPCOMP6",
 390         .owner          = THIS_MODULE,
 391         .proto          = IPPROTO_COMP,
 392         .init_state     = ipcomp6_init_state,
 393         .destructor     = ipcomp6_destroy,
 394         .input          = ipcomp6_input,
 395         .output         = ipcomp6_output,
 396 };
 397
 398 static struct inet6_protocol ipcomp6_protocol =
 399 {
 400         .handler        = xfrm6_rcv,
 401         .err_handler    = ipcomp6_err,
 402         .flags          = INET6_PROTO_NOPOLICY,
 403 };
 404
 405 static int __init ipcomp6_init(void)
 406 {
 407         if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
 408                 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n");
 409                 return -EAGAIN;
 410         }
 411         if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
 412                 printk(KERN_INFO "ipcomp6 init: can't add protocol\n");
 413                 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
 414                 return -EAGAIN;
 415         }
 416         return 0;
 417 }
 418
 419 static void __exit ipcomp6_fini(void)
 420 {
 421         if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0)
 422                 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n");
 423         if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
 424                 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n");
 425 }
 426
 427 module_init(ipcomp6_init);
 428 module_exit(ipcomp6_fini);
 429 MODULE_LICENSE("GPL");
 430 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
 431 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
 432
 433