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   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/module.h>
  34 #include <net/ip.h>
  35 #include <net/xfrm.h>
  36 #include <net/ipcomp.h>
  37 #include <asm/semaphore.h>
  38 #include <linux/crypto.h>
  39 #include <linux/pfkeyv2.h>
  40 #include <linux/random.h>
  41 #include <linux/percpu.h>
  42 #include <linux/smp.h>
  43 #include <linux/list.h>
  44 #include <linux/vmalloc.h>
  45 #include <linux/rtnetlink.h>
  46 #include <net/icmp.h>
  47 #include <net/ipv6.h>
  48 #include <net/protocol.h>
  49 #include <linux/ipv6.h>
  50 #include <linux/icmpv6.h>
  51 #include <linux/mutex.h>
  52
  53 struct ipcomp6_tfms {
  54         struct list_head list;
  55         struct crypto_comp **tfms;
  56         int users;
  57 };
  58
  59 static DEFINE_MUTEX(ipcomp6_resource_mutex);
  60 static void **ipcomp6_scratches;
  61 static int ipcomp6_scratch_users;
  62 static LIST_HEAD(ipcomp6_tfms_list);
  63
  64 static int ipcomp6_input(struct xfrm_state *x, struct sk_buff *skb)
  65 {
  66         int err = -ENOMEM;
  67         struct ip_comp_hdr *ipch;
  68         int plen, dlen;
  69         struct ipcomp_data *ipcd = x->data;
  70         u8 *start, *scratch;
  71         struct crypto_comp *tfm;
  72         int cpu;
  73
  74         if (skb_linearize_cow(skb))
  75                 goto out;
  76
  77         skb->ip_summed = CHECKSUM_NONE;
  78
  79         /* Remove ipcomp header and decompress original payload */
  80         ipch = (void *)skb->data;
  81         skb->transport_header = skb->network_header + sizeof(*ipch);
  82         __skb_pull(skb, sizeof(*ipch));
  83
  84         /* decompression */
  85         plen = skb->len;
  86         dlen = IPCOMP_SCRATCH_SIZE;
  87         start = skb->data;
  88
  89         cpu = get_cpu();
  90         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
  91         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
  92
  93         err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
  94         if (err)
  95                 goto out_put_cpu;
  96
  97         if (dlen < (plen + sizeof(*ipch))) {
  98                 err = -EINVAL;
  99                 goto out_put_cpu;
 100         }
 101
 102         err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
 103         if (err) {
 104                 goto out_put_cpu;
 105         }
 106
 107         skb->truesize += dlen - plen;
 108         __skb_put(skb, dlen - plen);
 109         skb_copy_to_linear_data(skb, scratch, dlen);
 110         err = ipch->nexthdr;
 111
 112 out_put_cpu:
 113         put_cpu();
 114 out:
 115         return err;
 116 }
 117
 118 static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb)
 119 {
 120         int err;
 121         struct ip_comp_hdr *ipch;
 122         struct ipcomp_data *ipcd = x->data;
 123         int plen, dlen;
 124         u8 *start, *scratch;
 125         struct crypto_comp *tfm;
 126         int cpu;
 127
 128         /* check whether datagram len is larger than threshold */
 129         if (skb->len < ipcd->threshold) {
 130                 goto out_ok;
 131         }
 132
 133         if (skb_linearize_cow(skb))
 134                 goto out_ok;
 135
 136         /* compression */
 137         plen = skb->len;
 138         dlen = IPCOMP_SCRATCH_SIZE;
 139         start = skb->data;
 140
 141         cpu = get_cpu();
 142         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
 143         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 144
 145         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
 146         if (err || (dlen + sizeof(*ipch)) >= plen) {
 147                 put_cpu();
 148                 goto out_ok;
 149         }
 150         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
 151         put_cpu();
 152         pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
 153
 154         /* insert ipcomp header and replace datagram */
 155         ipch = ip_comp_hdr(skb);
 156         ipch->nexthdr = *skb_mac_header(skb);
 157         ipch->flags = 0;
 158         ipch->cpi = htons((u16 )ntohl(x->id.spi));
 159         *skb_mac_header(skb) = IPPROTO_COMP;
 160
 161 out_ok:
 162         skb_push(skb, -skb_network_offset(skb));
 163
 164         return 0;
 165 }
 166
 167 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 168                                 int type, int code, int offset, __be32 info)
 169 {
 170         __be32 spi;
 171         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 172         struct ip_comp_hdr *ipcomph =
 173                 (struct ip_comp_hdr *)(skb->data + offset);
 174         struct xfrm_state *x;
 175
 176         if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG)
 177                 return;
 178
 179         spi = htonl(ntohs(ipcomph->cpi));
 180         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6);
 181         if (!x)
 182                 return;
 183
 184         printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIP6_FMT "\n",
 185                         spi, NIP6(iph->daddr));
 186         xfrm_state_put(x);
 187 }
 188
 189 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
 190 {
 191         struct xfrm_state *t = NULL;
 192         u8 mode = XFRM_MODE_TUNNEL;
 193
 194         t = xfrm_state_alloc();
 195         if (!t)
 196                 goto out;
 197
 198         t->id.proto = IPPROTO_IPV6;
 199         t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);
 200         if (!t->id.spi)
 201                 goto error;
 202
 203         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
 204         memcpy(&t->sel, &x->sel, sizeof(t->sel));
 205         t->props.family = AF_INET6;
 206         if (x->props.mode == XFRM_MODE_BEET)
 207                 mode = x->props.mode;
 208         t->props.mode = mode;
 209         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
 210
 211         if (xfrm_init_state(t))
 212                 goto error;
 213
 214         atomic_set(&t->tunnel_users, 1);
 215
 216 out:
 217         return t;
 218
 219 error:
 220         t->km.state = XFRM_STATE_DEAD;
 221         xfrm_state_put(t);
 222         t = NULL;
 223         goto out;
 224 }
 225
 226 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
 227 {
 228         int err = 0;
 229         struct xfrm_state *t = NULL;
 230         __be32 spi;
 231
 232         spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
 233         if (spi)
 234                 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
 235                                               spi, IPPROTO_IPV6, AF_INET6);
 236         if (!t) {
 237                 t = ipcomp6_tunnel_create(x);
 238                 if (!t) {
 239                         err = -EINVAL;
 240                         goto out;
 241                 }
 242                 xfrm_state_insert(t);
 243                 xfrm_state_hold(t);
 244         }
 245         x->tunnel = t;
 246         atomic_inc(&t->tunnel_users);
 247
 248 out:
 249         return err;
 250 }
 251
 252 static void ipcomp6_free_scratches(void)
 253 {
 254         int i;
 255         void **scratches;
 256
 257         if (--ipcomp6_scratch_users)
 258                 return;
 259
 260         scratches = ipcomp6_scratches;
 261         if (!scratches)
 262                 return;
 263
 264         for_each_possible_cpu(i) {
 265                 void *scratch = *per_cpu_ptr(scratches, i);
 266
 267                 vfree(scratch);
 268         }
 269
 270         free_percpu(scratches);
 271 }
 272
 273 static void **ipcomp6_alloc_scratches(void)
 274 {
 275         int i;
 276         void **scratches;
 277
 278         if (ipcomp6_scratch_users++)
 279                 return ipcomp6_scratches;
 280
 281         scratches = alloc_percpu(void *);
 282         if (!scratches)
 283                 return NULL;
 284
 285         ipcomp6_scratches = scratches;
 286
 287         for_each_possible_cpu(i) {
 288                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
 289                 if (!scratch)
 290                         return NULL;
 291                 *per_cpu_ptr(scratches, i) = scratch;
 292         }
 293
 294         return scratches;
 295 }
 296
 297 static void ipcomp6_free_tfms(struct crypto_comp **tfms)
 298 {
 299         struct ipcomp6_tfms *pos;
 300         int cpu;
 301
 302         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 303                 if (pos->tfms == tfms)
 304                         break;
 305         }
 306
 307         BUG_TRAP(pos);
 308
 309         if (--pos->users)
 310                 return;
 311
 312         list_del(&pos->list);
 313         kfree(pos);
 314
 315         if (!tfms)
 316                 return;
 317
 318         for_each_possible_cpu(cpu) {
 319                 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
 320                 crypto_free_comp(tfm);
 321         }
 322         free_percpu(tfms);
 323 }
 324
 325 static struct crypto_comp **ipcomp6_alloc_tfms(const char *alg_name)
 326 {
 327         struct ipcomp6_tfms *pos;
 328         struct crypto_comp **tfms;
 329         int cpu;
 330
 331         /* This can be any valid CPU ID so we don't need locking. */
 332         cpu = raw_smp_processor_id();
 333
 334         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 335                 struct crypto_comp *tfm;
 336
 337                 tfms = pos->tfms;
 338                 tfm = *per_cpu_ptr(tfms, cpu);
 339
 340                 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
 341                         pos->users++;
 342                         return tfms;
 343                 }
 344         }
 345
 346         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
 347         if (!pos)
 348                 return NULL;
 349
 350         pos->users = 1;
 351         INIT_LIST_HEAD(&pos->list);
 352         list_add(&pos->list, &ipcomp6_tfms_list);
 353
 354         pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
 355         if (!tfms)
 356                 goto error;
 357
 358         for_each_possible_cpu(cpu) {
 359                 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
 360                                                             CRYPTO_ALG_ASYNC);
 361                 if (!tfm)
 362                         goto error;
 363                 *per_cpu_ptr(tfms, cpu) = tfm;
 364         }
 365
 366         return tfms;
 367
 368 error:
 369         ipcomp6_free_tfms(tfms);
 370         return NULL;
 371 }
 372
 373 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
 374 {
 375         if (ipcd->tfms)
 376                 ipcomp6_free_tfms(ipcd->tfms);
 377         ipcomp6_free_scratches();
 378 }
 379
 380 static void ipcomp6_destroy(struct xfrm_state *x)
 381 {
 382         struct ipcomp_data *ipcd = x->data;
 383         if (!ipcd)
 384                 return;
 385         xfrm_state_delete_tunnel(x);
 386         mutex_lock(&ipcomp6_resource_mutex);
 387         ipcomp6_free_data(ipcd);
 388         mutex_unlock(&ipcomp6_resource_mutex);
 389         kfree(ipcd);
 390
 391         xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
 392 }
 393
 394 static int ipcomp6_init_state(struct xfrm_state *x)
 395 {
 396         int err;
 397         struct ipcomp_data *ipcd;
 398         struct xfrm_algo_desc *calg_desc;
 399
 400         err = -EINVAL;
 401         if (!x->calg)
 402                 goto out;
 403
 404         if (x->encap)
 405                 goto out;
 406
 407         err = -ENOMEM;
 408         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
 409         if (!ipcd)
 410                 goto out;
 411
 412         x->props.header_len = 0;
 413         switch (x->props.mode) {
 414         case XFRM_MODE_BEET:
 415         case XFRM_MODE_TRANSPORT:
 416                 break;
 417         case XFRM_MODE_TUNNEL:
 418                 x->props.header_len += sizeof(struct ipv6hdr);
 419         default:
 420                 goto error;
 421         }
 422
 423         mutex_lock(&ipcomp6_resource_mutex);
 424         if (!ipcomp6_alloc_scratches())
 425                 goto error;
 426
 427         ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name);
 428         if (!ipcd->tfms)
 429                 goto error;
 430         mutex_unlock(&ipcomp6_resource_mutex);
 431
 432         if (x->props.mode == XFRM_MODE_TUNNEL) {
 433                 err = ipcomp6_tunnel_attach(x);
 434                 if (err)
 435                         goto error_tunnel;
 436         }
 437
 438         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
 439         BUG_ON(!calg_desc);
 440         ipcd->threshold = calg_desc->uinfo.comp.threshold;
 441         x->data = ipcd;
 442         err = 0;
 443 out:
 444         return err;
 445 error_tunnel:
 446         mutex_lock(&ipcomp6_resource_mutex);
 447 error:
 448         ipcomp6_free_data(ipcd);
 449         mutex_unlock(&ipcomp6_resource_mutex);
 450         kfree(ipcd);
 451
 452         goto out;
 453 }
 454
 455 static struct xfrm_type ipcomp6_type =
 456 {
 457         .description    = "IPCOMP6",
 458         .owner          = THIS_MODULE,
 459         .proto          = IPPROTO_COMP,
 460         .init_state     = ipcomp6_init_state,
 461         .destructor     = ipcomp6_destroy,
 462         .input          = ipcomp6_input,
 463         .output         = ipcomp6_output,
 464         .hdr_offset     = xfrm6_find_1stfragopt,
 465 };
 466
 467 static struct inet6_protocol ipcomp6_protocol =
 468 {
 469         .handler        = xfrm6_rcv,
 470         .err_handler    = ipcomp6_err,
 471         .flags          = INET6_PROTO_NOPOLICY,
 472 };
 473
 474 static int __init ipcomp6_init(void)
 475 {
 476         if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
 477                 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n");
 478                 return -EAGAIN;
 479         }
 480         if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
 481                 printk(KERN_INFO "ipcomp6 init: can't add protocol\n");
 482                 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
 483                 return -EAGAIN;
 484         }
 485         return 0;
 486 }
 487
 488 static void __exit ipcomp6_fini(void)
 489 {
 490         if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0)
 491                 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n");
 492         if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
 493                 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n");
 494 }
 495
 496 module_init(ipcomp6_init);
 497 module_exit(ipcomp6_fini);
 498 MODULE_LICENSE("GPL");
 499 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
 500 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
 501
 502 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP);