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