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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 ipv6_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                 err = -EINVAL;
  97                 goto out_put_cpu;
  98         }
  99
 100         if (dlen < (plen + sizeof(struct ipv6_comp_hdr))) {
 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 = ipch->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 ipv6hdr *top_iph;
 125         struct ipv6_comp_hdr *ipch;
 126         struct ipcomp_data *ipcd = x->data;
 127         int plen, dlen;
 128         u8 *start, *scratch;
 129         struct crypto_comp *tfm;
 130         int cpu;
 131         int hdr_len;
 132
 133         skb_push(skb, -skb_network_offset(skb));
 134         hdr_len = skb_transport_offset(skb);
 135
 136         /* check whether datagram len is larger than threshold */
 137         if ((skb->len - hdr_len) < ipcd->threshold) {
 138                 goto out_ok;
 139         }
 140
 141         if (skb_linearize_cow(skb))
 142                 goto out_ok;
 143
 144         /* compression */
 145         plen = skb->len - hdr_len;
 146         dlen = IPCOMP_SCRATCH_SIZE;
 147         start = skb_transport_header(skb);
 148
 149         cpu = get_cpu();
 150         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
 151         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 152
 153         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
 154         if (err || (dlen + sizeof(struct ipv6_comp_hdr)) >= plen) {
 155                 put_cpu();
 156                 goto out_ok;
 157         }
 158         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
 159         put_cpu();
 160         pskb_trim(skb, hdr_len + dlen + sizeof(struct ip_comp_hdr));
 161
 162         /* insert ipcomp header and replace datagram */
 163         top_iph = ipv6_hdr(skb);
 164
 165         top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 166
 167         ipch = (struct ipv6_comp_hdr *)start;
 168         ipch->nexthdr = *skb_mac_header(skb);
 169         ipch->flags = 0;
 170         ipch->cpi = htons((u16 )ntohl(x->id.spi));
 171         *skb_mac_header(skb) = IPPROTO_COMP;
 172
 173 out_ok:
 174         return 0;
 175 }
 176
 177 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 178                                 int type, int code, int offset, __be32 info)
 179 {
 180         __be32 spi;
 181         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 182         struct ipv6_comp_hdr *ipcomph = (struct ipv6_comp_hdr*)(skb->data+offset);
 183         struct xfrm_state *x;
 184
 185         if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG)
 186                 return;
 187
 188         spi = htonl(ntohs(ipcomph->cpi));
 189         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6);
 190         if (!x)
 191                 return;
 192
 193         printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIP6_FMT "\n",
 194                         spi, NIP6(iph->daddr));
 195         xfrm_state_put(x);
 196 }
 197
 198 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
 199 {
 200         struct xfrm_state *t = NULL;
 201         u8 mode = XFRM_MODE_TUNNEL;
 202
 203         t = xfrm_state_alloc();
 204         if (!t)
 205                 goto out;
 206
 207         t->id.proto = IPPROTO_IPV6;
 208         t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);
 209         if (!t->id.spi)
 210                 goto error;
 211
 212         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
 213         memcpy(&t->sel, &x->sel, sizeof(t->sel));
 214         t->props.family = AF_INET6;
 215         if (x->props.mode == XFRM_MODE_BEET)
 216                 mode = x->props.mode;
 217         t->props.mode = mode;
 218         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
 219
 220         if (xfrm_init_state(t))
 221                 goto error;
 222
 223         atomic_set(&t->tunnel_users, 1);
 224
 225 out:
 226         return t;
 227
 228 error:
 229         t->km.state = XFRM_STATE_DEAD;
 230         xfrm_state_put(t);
 231         t = NULL;
 232         goto out;
 233 }
 234
 235 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
 236 {
 237         int err = 0;
 238         struct xfrm_state *t = NULL;
 239         __be32 spi;
 240
 241         spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
 242         if (spi)
 243                 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
 244                                               spi, IPPROTO_IPV6, AF_INET6);
 245         if (!t) {
 246                 t = ipcomp6_tunnel_create(x);
 247                 if (!t) {
 248                         err = -EINVAL;
 249                         goto out;
 250                 }
 251                 xfrm_state_insert(t);
 252                 xfrm_state_hold(t);
 253         }
 254         x->tunnel = t;
 255         atomic_inc(&t->tunnel_users);
 256
 257 out:
 258         return err;
 259 }
 260
 261 static void ipcomp6_free_scratches(void)
 262 {
 263         int i;
 264         void **scratches;
 265
 266         if (--ipcomp6_scratch_users)
 267                 return;
 268
 269         scratches = ipcomp6_scratches;
 270         if (!scratches)
 271                 return;
 272
 273         for_each_possible_cpu(i) {
 274                 void *scratch = *per_cpu_ptr(scratches, i);
 275
 276                 vfree(scratch);
 277         }
 278
 279         free_percpu(scratches);
 280 }
 281
 282 static void **ipcomp6_alloc_scratches(void)
 283 {
 284         int i;
 285         void **scratches;
 286
 287         if (ipcomp6_scratch_users++)
 288                 return ipcomp6_scratches;
 289
 290         scratches = alloc_percpu(void *);
 291         if (!scratches)
 292                 return NULL;
 293
 294         ipcomp6_scratches = scratches;
 295
 296         for_each_possible_cpu(i) {
 297                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
 298                 if (!scratch)
 299                         return NULL;
 300                 *per_cpu_ptr(scratches, i) = scratch;
 301         }
 302
 303         return scratches;
 304 }
 305
 306 static void ipcomp6_free_tfms(struct crypto_comp **tfms)
 307 {
 308         struct ipcomp6_tfms *pos;
 309         int cpu;
 310
 311         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 312                 if (pos->tfms == tfms)
 313                         break;
 314         }
 315
 316         BUG_TRAP(pos);
 317
 318         if (--pos->users)
 319                 return;
 320
 321         list_del(&pos->list);
 322         kfree(pos);
 323
 324         if (!tfms)
 325                 return;
 326
 327         for_each_possible_cpu(cpu) {
 328                 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
 329                 crypto_free_comp(tfm);
 330         }
 331         free_percpu(tfms);
 332 }
 333
 334 static struct crypto_comp **ipcomp6_alloc_tfms(const char *alg_name)
 335 {
 336         struct ipcomp6_tfms *pos;
 337         struct crypto_comp **tfms;
 338         int cpu;
 339
 340         /* This can be any valid CPU ID so we don't need locking. */
 341         cpu = raw_smp_processor_id();
 342
 343         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 344                 struct crypto_comp *tfm;
 345
 346                 tfms = pos->tfms;
 347                 tfm = *per_cpu_ptr(tfms, cpu);
 348
 349                 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
 350                         pos->users++;
 351                         return tfms;
 352                 }
 353         }
 354
 355         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
 356         if (!pos)
 357                 return NULL;
 358
 359         pos->users = 1;
 360         INIT_LIST_HEAD(&pos->list);
 361         list_add(&pos->list, &ipcomp6_tfms_list);
 362
 363         pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
 364         if (!tfms)
 365                 goto error;
 366
 367         for_each_possible_cpu(cpu) {
 368                 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
 369                                                             CRYPTO_ALG_ASYNC);
 370                 if (!tfm)
 371                         goto error;
 372                 *per_cpu_ptr(tfms, cpu) = tfm;
 373         }
 374
 375         return tfms;
 376
 377 error:
 378         ipcomp6_free_tfms(tfms);
 379         return NULL;
 380 }
 381
 382 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
 383 {
 384         if (ipcd->tfms)
 385                 ipcomp6_free_tfms(ipcd->tfms);
 386         ipcomp6_free_scratches();
 387 }
 388
 389 static void ipcomp6_destroy(struct xfrm_state *x)
 390 {
 391         struct ipcomp_data *ipcd = x->data;
 392         if (!ipcd)
 393                 return;
 394         xfrm_state_delete_tunnel(x);
 395         mutex_lock(&ipcomp6_resource_mutex);
 396         ipcomp6_free_data(ipcd);
 397         mutex_unlock(&ipcomp6_resource_mutex);
 398         kfree(ipcd);
 399
 400         xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
 401 }
 402
 403 static int ipcomp6_init_state(struct xfrm_state *x)
 404 {
 405         int err;
 406         struct ipcomp_data *ipcd;
 407         struct xfrm_algo_desc *calg_desc;
 408
 409         err = -EINVAL;
 410         if (!x->calg)
 411                 goto out;
 412
 413         if (x->encap)
 414                 goto out;
 415
 416         err = -ENOMEM;
 417         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
 418         if (!ipcd)
 419                 goto out;
 420
 421         x->props.header_len = 0;
 422         if (x->props.mode == XFRM_MODE_TUNNEL)
 423                 x->props.header_len += sizeof(struct ipv6hdr);
 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 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);