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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/scatterlist.h>
  38 #include <asm/semaphore.h>
  39 #include <linux/crypto.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 ipv6hdr *top_iph;
 123         struct ip_comp_hdr *ipch;
 124         struct ipcomp_data *ipcd = x->data;
 125         int plen, dlen;
 126         u8 *start, *scratch;
 127         struct crypto_comp *tfm;
 128         int cpu;
 129         int hdr_len;
 130
 131         skb_push(skb, -skb_network_offset(skb));
 132         hdr_len = skb_transport_offset(skb);
 133
 134         /* check whether datagram len is larger than threshold */
 135         if ((skb->len - hdr_len) < ipcd->threshold) {
 136                 goto out_ok;
 137         }
 138
 139         if (skb_linearize_cow(skb))
 140                 goto out_ok;
 141
 142         /* compression */
 143         plen = skb->len - hdr_len;
 144         dlen = IPCOMP_SCRATCH_SIZE;
 145         start = skb_transport_header(skb);
 146
 147         cpu = get_cpu();
 148         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
 149         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 150
 151         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
 152         if (err || (dlen + sizeof(*ipch)) >= plen) {
 153                 put_cpu();
 154                 goto out_ok;
 155         }
 156         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
 157         put_cpu();
 158         pskb_trim(skb, hdr_len + dlen + sizeof(struct ip_comp_hdr));
 159
 160         /* insert ipcomp header and replace datagram */
 161         top_iph = ipv6_hdr(skb);
 162
 163         top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 164
 165         ipch = ip_comp_hdr(skb);
 166         ipch->nexthdr = *skb_mac_header(skb);
 167         ipch->flags = 0;
 168         ipch->cpi = htons((u16 )ntohl(x->id.spi));
 169         *skb_mac_header(skb) = IPPROTO_COMP;
 170
 171 out_ok:
 172         return 0;
 173 }
 174
 175 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 176                                 int type, int code, int offset, __be32 info)
 177 {
 178         __be32 spi;
 179         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 180         struct ip_comp_hdr *ipcomph =
 181                 (struct ip_comp_hdr *)(skb->data + offset);
 182         struct xfrm_state *x;
 183
 184         if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG)
 185                 return;
 186
 187         spi = htonl(ntohs(ipcomph->cpi));
 188         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6);
 189         if (!x)
 190                 return;
 191
 192         printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIP6_FMT "\n",
 193                         spi, NIP6(iph->daddr));
 194         xfrm_state_put(x);
 195 }
 196
 197 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
 198 {
 199         struct xfrm_state *t = NULL;
 200         u8 mode = XFRM_MODE_TUNNEL;
 201
 202         t = xfrm_state_alloc();
 203         if (!t)
 204                 goto out;
 205
 206         t->id.proto = IPPROTO_IPV6;
 207         t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);
 208         if (!t->id.spi)
 209                 goto error;
 210
 211         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
 212         memcpy(&t->sel, &x->sel, sizeof(t->sel));
 213         t->props.family = AF_INET6;
 214         if (x->props.mode == XFRM_MODE_BEET)
 215                 mode = x->props.mode;
 216         t->props.mode = mode;
 217         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
 218
 219         if (xfrm_init_state(t))
 220                 goto error;
 221
 222         atomic_set(&t->tunnel_users, 1);
 223
 224 out:
 225         return t;
 226
 227 error:
 228         t->km.state = XFRM_STATE_DEAD;
 229         xfrm_state_put(t);
 230         t = NULL;
 231         goto out;
 232 }
 233
 234 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
 235 {
 236         int err = 0;
 237         struct xfrm_state *t = NULL;
 238         __be32 spi;
 239
 240         spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
 241         if (spi)
 242                 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
 243                                               spi, IPPROTO_IPV6, AF_INET6);
 244         if (!t) {
 245                 t = ipcomp6_tunnel_create(x);
 246                 if (!t) {
 247                         err = -EINVAL;
 248                         goto out;
 249                 }
 250                 xfrm_state_insert(t);
 251                 xfrm_state_hold(t);
 252         }
 253         x->tunnel = t;
 254         atomic_inc(&t->tunnel_users);
 255
 256 out:
 257         return err;
 258 }
 259
 260 static void ipcomp6_free_scratches(void)
 261 {
 262         int i;
 263         void **scratches;
 264
 265         if (--ipcomp6_scratch_users)
 266                 return;
 267
 268         scratches = ipcomp6_scratches;
 269         if (!scratches)
 270                 return;
 271
 272         for_each_possible_cpu(i) {
 273                 void *scratch = *per_cpu_ptr(scratches, i);
 274
 275                 vfree(scratch);
 276         }
 277
 278         free_percpu(scratches);
 279 }
 280
 281 static void **ipcomp6_alloc_scratches(void)
 282 {
 283         int i;
 284         void **scratches;
 285
 286         if (ipcomp6_scratch_users++)
 287                 return ipcomp6_scratches;
 288
 289         scratches = alloc_percpu(void *);
 290         if (!scratches)
 291                 return NULL;
 292
 293         ipcomp6_scratches = scratches;
 294
 295         for_each_possible_cpu(i) {
 296                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
 297                 if (!scratch)
 298                         return NULL;
 299                 *per_cpu_ptr(scratches, i) = scratch;
 300         }
 301
 302         return scratches;
 303 }
 304
 305 static void ipcomp6_free_tfms(struct crypto_comp **tfms)
 306 {
 307         struct ipcomp6_tfms *pos;
 308         int cpu;
 309
 310         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 311                 if (pos->tfms == tfms)
 312                         break;
 313         }
 314
 315         BUG_TRAP(pos);
 316
 317         if (--pos->users)
 318                 return;
 319
 320         list_del(&pos->list);
 321         kfree(pos);
 322
 323         if (!tfms)
 324                 return;
 325
 326         for_each_possible_cpu(cpu) {
 327                 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
 328                 crypto_free_comp(tfm);
 329         }
 330         free_percpu(tfms);
 331 }
 332
 333 static struct crypto_comp **ipcomp6_alloc_tfms(const char *alg_name)
 334 {
 335         struct ipcomp6_tfms *pos;
 336         struct crypto_comp **tfms;
 337         int cpu;
 338
 339         /* This can be any valid CPU ID so we don't need locking. */
 340         cpu = raw_smp_processor_id();
 341
 342         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 343                 struct crypto_comp *tfm;
 344
 345                 tfms = pos->tfms;
 346                 tfm = *per_cpu_ptr(tfms, cpu);
 347
 348                 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
 349                         pos->users++;
 350                         return tfms;
 351                 }
 352         }
 353
 354         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
 355         if (!pos)
 356                 return NULL;
 357
 358         pos->users = 1;
 359         INIT_LIST_HEAD(&pos->list);
 360         list_add(&pos->list, &ipcomp6_tfms_list);
 361
 362         pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
 363         if (!tfms)
 364                 goto error;
 365
 366         for_each_possible_cpu(cpu) {
 367                 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
 368                                                             CRYPTO_ALG_ASYNC);
 369                 if (!tfm)
 370                         goto error;
 371                 *per_cpu_ptr(tfms, cpu) = tfm;
 372         }
 373
 374         return tfms;
 375
 376 error:
 377         ipcomp6_free_tfms(tfms);
 378         return NULL;
 379 }
 380
 381 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
 382 {
 383         if (ipcd->tfms)
 384                 ipcomp6_free_tfms(ipcd->tfms);
 385         ipcomp6_free_scratches();
 386 }
 387
 388 static void ipcomp6_destroy(struct xfrm_state *x)
 389 {
 390         struct ipcomp_data *ipcd = x->data;
 391         if (!ipcd)
 392                 return;
 393         xfrm_state_delete_tunnel(x);
 394         mutex_lock(&ipcomp6_resource_mutex);
 395         ipcomp6_free_data(ipcd);
 396         mutex_unlock(&ipcomp6_resource_mutex);
 397         kfree(ipcd);
 398
 399         xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
 400 }
 401
 402 static int ipcomp6_init_state(struct xfrm_state *x)
 403 {
 404         int err;
 405         struct ipcomp_data *ipcd;
 406         struct xfrm_algo_desc *calg_desc;
 407
 408         err = -EINVAL;
 409         if (!x->calg)
 410                 goto out;
 411
 412         if (x->encap)
 413                 goto out;
 414
 415         err = -ENOMEM;
 416         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
 417         if (!ipcd)
 418                 goto out;
 419
 420         x->props.header_len = 0;
 421         if (x->props.mode == XFRM_MODE_TUNNEL)
 422                 x->props.header_len += sizeof(struct ipv6hdr);
 423
 424         mutex_lock(&ipcomp6_resource_mutex);
 425         if (!ipcomp6_alloc_scratches())
 426                 goto error;
 427
 428         ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name);
 429         if (!ipcd->tfms)
 430                 goto error;
 431         mutex_unlock(&ipcomp6_resource_mutex);
 432
 433         if (x->props.mode == XFRM_MODE_TUNNEL) {
 434                 err = ipcomp6_tunnel_attach(x);
 435                 if (err)
 436                         goto error_tunnel;
 437         }
 438
 439         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
 440         BUG_ON(!calg_desc);
 441         ipcd->threshold = calg_desc->uinfo.comp.threshold;
 442         x->data = ipcd;
 443         err = 0;
 444 out:
 445         return err;
 446 error_tunnel:
 447         mutex_lock(&ipcomp6_resource_mutex);
 448 error:
 449         ipcomp6_free_data(ipcd);
 450         mutex_unlock(&ipcomp6_resource_mutex);
 451         kfree(ipcd);
 452
 453         goto out;
 454 }
 455
 456 static struct xfrm_type ipcomp6_type =
 457 {
 458         .description    = "IPCOMP6",
 459         .owner          = THIS_MODULE,
 460         .proto          = IPPROTO_COMP,
 461         .init_state     = ipcomp6_init_state,
 462         .destructor     = ipcomp6_destroy,
 463         .input          = ipcomp6_input,
 464         .output         = ipcomp6_output,
 465         .hdr_offset     = xfrm6_find_1stfragopt,
 466 };
 467
 468 static struct inet6_protocol ipcomp6_protocol =
 469 {
 470         .handler        = xfrm6_rcv,
 471         .err_handler    = ipcomp6_err,
 472         .flags          = INET6_PROTO_NOPOLICY,
 473 };
 474
 475 static int __init ipcomp6_init(void)
 476 {
 477         if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
 478                 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n");
 479                 return -EAGAIN;
 480         }
 481         if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
 482                 printk(KERN_INFO "ipcomp6 init: can't add protocol\n");
 483                 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
 484                 return -EAGAIN;
 485         }
 486         return 0;
 487 }
 488
 489 static void __exit ipcomp6_fini(void)
 490 {
 491         if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0)
 492                 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n");
 493         if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
 494                 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n");
 495 }
 496
 497 module_init(ipcomp6_init);
 498 module_exit(ipcomp6_fini);
 499 MODULE_LICENSE("GPL");
 500 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
 501 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
 502
 503 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP);