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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 <linux/crypto.h>
  38 #include <linux/err.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 nexthdr;
  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         nexthdr = ipch->nexthdr;
  83
  84         skb->transport_header = skb->network_header + sizeof(*ipch);
  85         __skb_pull(skb, sizeof(*ipch));
  86
  87         /* decompression */
  88         plen = skb->len;
  89         dlen = IPCOMP_SCRATCH_SIZE;
  90         start = skb->data;
  91
  92         cpu = get_cpu();
  93         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
  94         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
  95
  96         err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
  97         if (err)
  98                 goto out_put_cpu;
  99
 100         if (dlen < (plen + sizeof(*ipch))) {
 101                 err = -EINVAL;
 102                 goto out_put_cpu;
 103         }
 104
 105         err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
 106         if (err) {
 107                 goto out_put_cpu;
 108         }
 109
 110         skb->truesize += dlen - plen;
 111         __skb_put(skb, dlen - plen);
 112         skb_copy_to_linear_data(skb, scratch, dlen);
 113         err = nexthdr;
 114
 115 out_put_cpu:
 116         put_cpu();
 117 out:
 118         return err;
 119 }
 120
 121 static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb)
 122 {
 123         int err;
 124         struct ip_comp_hdr *ipch;
 125         struct ipcomp_data *ipcd = x->data;
 126         int plen, dlen;
 127         u8 *start, *scratch;
 128         struct crypto_comp *tfm;
 129         int cpu;
 130
 131         /* check whether datagram len is larger than threshold */
 132         if (skb->len < ipcd->threshold) {
 133                 goto out_ok;
 134         }
 135
 136         if (skb_linearize_cow(skb))
 137                 goto out_ok;
 138
 139         /* compression */
 140         plen = skb->len;
 141         dlen = IPCOMP_SCRATCH_SIZE;
 142         start = skb->data;
 143
 144         cpu = get_cpu();
 145         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
 146         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 147
 148         local_bh_disable();
 149         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
 150         local_bh_enable();
 151         if (err || (dlen + sizeof(*ipch)) >= plen) {
 152                 put_cpu();
 153                 goto out_ok;
 154         }
 155         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
 156         put_cpu();
 157         pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
 158
 159         /* insert ipcomp header and replace datagram */
 160         ipch = ip_comp_hdr(skb);
 161         ipch->nexthdr = *skb_mac_header(skb);
 162         ipch->flags = 0;
 163         ipch->cpi = htons((u16 )ntohl(x->id.spi));
 164         *skb_mac_header(skb) = IPPROTO_COMP;
 165
 166 out_ok:
 167         skb_push(skb, -skb_network_offset(skb));
 168
 169         return 0;
 170 }
 171
 172 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 173                                 int type, int code, int offset, __be32 info)
 174 {
 175         __be32 spi;
 176         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 177         struct ip_comp_hdr *ipcomph =
 178                 (struct ip_comp_hdr *)(skb->data + offset);
 179         struct xfrm_state *x;
 180
 181         if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG)
 182                 return;
 183
 184         spi = htonl(ntohs(ipcomph->cpi));
 185         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6);
 186         if (!x)
 187                 return;
 188
 189         printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIP6_FMT "\n",
 190                         spi, NIP6(iph->daddr));
 191         xfrm_state_put(x);
 192 }
 193
 194 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
 195 {
 196         struct xfrm_state *t = NULL;
 197
 198         t = xfrm_state_alloc();
 199         if (!t)
 200                 goto out;
 201
 202         t->id.proto = IPPROTO_IPV6;
 203         t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);
 204         if (!t->id.spi)
 205                 goto error;
 206
 207         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
 208         memcpy(&t->sel, &x->sel, sizeof(t->sel));
 209         t->props.family = AF_INET6;
 210         t->props.mode = x->props.mode;
 211         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
 212
 213         if (xfrm_init_state(t))
 214                 goto error;
 215
 216         atomic_set(&t->tunnel_users, 1);
 217
 218 out:
 219         return t;
 220
 221 error:
 222         t->km.state = XFRM_STATE_DEAD;
 223         xfrm_state_put(t);
 224         t = NULL;
 225         goto out;
 226 }
 227
 228 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
 229 {
 230         int err = 0;
 231         struct xfrm_state *t = NULL;
 232         __be32 spi;
 233
 234         spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
 235         if (spi)
 236                 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
 237                                               spi, IPPROTO_IPV6, AF_INET6);
 238         if (!t) {
 239                 t = ipcomp6_tunnel_create(x);
 240                 if (!t) {
 241                         err = -EINVAL;
 242                         goto out;
 243                 }
 244                 xfrm_state_insert(t);
 245                 xfrm_state_hold(t);
 246         }
 247         x->tunnel = t;
 248         atomic_inc(&t->tunnel_users);
 249
 250 out:
 251         return err;
 252 }
 253
 254 static void ipcomp6_free_scratches(void)
 255 {
 256         int i;
 257         void **scratches;
 258
 259         if (--ipcomp6_scratch_users)
 260                 return;
 261
 262         scratches = ipcomp6_scratches;
 263         if (!scratches)
 264                 return;
 265
 266         for_each_possible_cpu(i) {
 267                 void *scratch = *per_cpu_ptr(scratches, i);
 268
 269                 vfree(scratch);
 270         }
 271
 272         free_percpu(scratches);
 273 }
 274
 275 static void **ipcomp6_alloc_scratches(void)
 276 {
 277         int i;
 278         void **scratches;
 279
 280         if (ipcomp6_scratch_users++)
 281                 return ipcomp6_scratches;
 282
 283         scratches = alloc_percpu(void *);
 284         if (!scratches)
 285                 return NULL;
 286
 287         ipcomp6_scratches = scratches;
 288
 289         for_each_possible_cpu(i) {
 290                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
 291                 if (!scratch)
 292                         return NULL;
 293                 *per_cpu_ptr(scratches, i) = scratch;
 294         }
 295
 296         return scratches;
 297 }
 298
 299 static void ipcomp6_free_tfms(struct crypto_comp **tfms)
 300 {
 301         struct ipcomp6_tfms *pos;
 302         int cpu;
 303
 304         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 305                 if (pos->tfms == tfms)
 306                         break;
 307         }
 308
 309         BUG_TRAP(pos);
 310
 311         if (--pos->users)
 312                 return;
 313
 314         list_del(&pos->list);
 315         kfree(pos);
 316
 317         if (!tfms)
 318                 return;
 319
 320         for_each_possible_cpu(cpu) {
 321                 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
 322                 crypto_free_comp(tfm);
 323         }
 324         free_percpu(tfms);
 325 }
 326
 327 static struct crypto_comp **ipcomp6_alloc_tfms(const char *alg_name)
 328 {
 329         struct ipcomp6_tfms *pos;
 330         struct crypto_comp **tfms;
 331         int cpu;
 332
 333         /* This can be any valid CPU ID so we don't need locking. */
 334         cpu = raw_smp_processor_id();
 335
 336         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 337                 struct crypto_comp *tfm;
 338
 339                 tfms = pos->tfms;
 340                 tfm = *per_cpu_ptr(tfms, cpu);
 341
 342                 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
 343                         pos->users++;
 344                         return tfms;
 345                 }
 346         }
 347
 348         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
 349         if (!pos)
 350                 return NULL;
 351
 352         pos->users = 1;
 353         INIT_LIST_HEAD(&pos->list);
 354         list_add(&pos->list, &ipcomp6_tfms_list);
 355
 356         pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
 357         if (!tfms)
 358                 goto error;
 359
 360         for_each_possible_cpu(cpu) {
 361                 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
 362                                                             CRYPTO_ALG_ASYNC);
 363                 if (IS_ERR(tfm))
 364                         goto error;
 365                 *per_cpu_ptr(tfms, cpu) = tfm;
 366         }
 367
 368         return tfms;
 369
 370 error:
 371         ipcomp6_free_tfms(tfms);
 372         return NULL;
 373 }
 374
 375 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
 376 {
 377         if (ipcd->tfms)
 378                 ipcomp6_free_tfms(ipcd->tfms);
 379         ipcomp6_free_scratches();
 380 }
 381
 382 static void ipcomp6_destroy(struct xfrm_state *x)
 383 {
 384         struct ipcomp_data *ipcd = x->data;
 385         if (!ipcd)
 386                 return;
 387         xfrm_state_delete_tunnel(x);
 388         mutex_lock(&ipcomp6_resource_mutex);
 389         ipcomp6_free_data(ipcd);
 390         mutex_unlock(&ipcomp6_resource_mutex);
 391         kfree(ipcd);
 392
 393         xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
 394 }
 395
 396 static int ipcomp6_init_state(struct xfrm_state *x)
 397 {
 398         int err;
 399         struct ipcomp_data *ipcd;
 400         struct xfrm_algo_desc *calg_desc;
 401
 402         err = -EINVAL;
 403         if (!x->calg)
 404                 goto out;
 405
 406         if (x->encap)
 407                 goto out;
 408
 409         x->props.header_len = 0;
 410         switch (x->props.mode) {
 411         case XFRM_MODE_TRANSPORT:
 412                 break;
 413         case XFRM_MODE_TUNNEL:
 414                 x->props.header_len += sizeof(struct ipv6hdr);
 415                 break;
 416         default:
 417                 goto out;
 418         }
 419
 420         err = -ENOMEM;
 421         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
 422         if (!ipcd)
 423                 goto out;
 424
 425         mutex_lock(&ipcomp6_resource_mutex);
 426         if (!ipcomp6_alloc_scratches())
 427                 goto error;
 428
 429         ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name);
 430         if (!ipcd->tfms)
 431                 goto error;
 432         mutex_unlock(&ipcomp6_resource_mutex);
 433
 434         if (x->props.mode == XFRM_MODE_TUNNEL) {
 435                 err = ipcomp6_tunnel_attach(x);
 436                 if (err)
 437                         goto error_tunnel;
 438         }
 439
 440         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
 441         BUG_ON(!calg_desc);
 442         ipcd->threshold = calg_desc->uinfo.comp.threshold;
 443         x->data = ipcd;
 444         err = 0;
 445 out:
 446         return err;
 447 error_tunnel:
 448         mutex_lock(&ipcomp6_resource_mutex);
 449 error:
 450         ipcomp6_free_data(ipcd);
 451         mutex_unlock(&ipcomp6_resource_mutex);
 452         kfree(ipcd);
 453
 454         goto out;
 455 }
 456
 457 static const struct xfrm_type ipcomp6_type =
 458 {
 459         .description    = "IPCOMP6",
 460         .owner          = THIS_MODULE,
 461         .proto          = IPPROTO_COMP,
 462         .init_state     = ipcomp6_init_state,
 463         .destructor     = ipcomp6_destroy,
 464         .input          = ipcomp6_input,
 465         .output         = ipcomp6_output,
 466         .hdr_offset     = xfrm6_find_1stfragopt,
 467 };
 468
 469 static struct inet6_protocol ipcomp6_protocol =
 470 {
 471         .handler        = xfrm6_rcv,
 472         .err_handler    = ipcomp6_err,
 473         .flags          = INET6_PROTO_NOPOLICY,
 474 };
 475
 476 static int __init ipcomp6_init(void)
 477 {
 478         if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
 479                 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n");
 480                 return -EAGAIN;
 481         }
 482         if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
 483                 printk(KERN_INFO "ipcomp6 init: can't add protocol\n");
 484                 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
 485                 return -EAGAIN;
 486         }
 487         return 0;
 488 }
 489
 490 static void __exit ipcomp6_fini(void)
 491 {
 492         if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0)
 493                 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n");
 494         if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
 495                 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n");
 496 }
 497
 498 module_init(ipcomp6_init);
 499 module_exit(ipcomp6_fini);
 500 MODULE_LICENSE("GPL");
 501 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
 502 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
 503
 504 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP);