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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 nexthdr;
  68         int err = -ENOMEM;
  69         struct ip_comp_hdr *ipch;
  70         int plen, dlen;
  71         struct ipcomp_data *ipcd = x->data;
  72         u8 *start, *scratch;
  73         struct crypto_comp *tfm;
  74         int cpu;
  75
  76         if (skb_linearize_cow(skb))
  77                 goto out;
  78
  79         skb->ip_summed = CHECKSUM_NONE;
  80
  81         /* Remove ipcomp header and decompress original payload */
  82         ipch = (void *)skb->data;
  83         nexthdr = ipch->nexthdr;
  84
  85         skb->transport_header = skb->network_header + sizeof(*ipch);
  86         __skb_pull(skb, sizeof(*ipch));
  87
  88         /* decompression */
  89         plen = skb->len;
  90         dlen = IPCOMP_SCRATCH_SIZE;
  91         start = skb->data;
  92
  93         cpu = get_cpu();
  94         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
  95         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
  96
  97         err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
  98         if (err)
  99                 goto out_put_cpu;
 100
 101         if (dlen < (plen + sizeof(*ipch))) {
 102                 err = -EINVAL;
 103                 goto out_put_cpu;
 104         }
 105
 106         err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
 107         if (err) {
 108                 goto out_put_cpu;
 109         }
 110
 111         skb->truesize += dlen - plen;
 112         __skb_put(skb, dlen - plen);
 113         skb_copy_to_linear_data(skb, scratch, dlen);
 114         err = nexthdr;
 115
 116 out_put_cpu:
 117         put_cpu();
 118 out:
 119         return err;
 120 }
 121
 122 static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb)
 123 {
 124         int err;
 125         struct ip_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
 132         /* check whether datagram len is larger than threshold */
 133         if (skb->len < ipcd->threshold) {
 134                 goto out_ok;
 135         }
 136
 137         if (skb_linearize_cow(skb))
 138                 goto out_ok;
 139
 140         /* compression */
 141         plen = skb->len;
 142         dlen = IPCOMP_SCRATCH_SIZE;
 143         start = skb->data;
 144
 145         cpu = get_cpu();
 146         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
 147         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 148
 149         local_bh_disable();
 150         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
 151         local_bh_enable();
 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, dlen + sizeof(struct ip_comp_hdr));
 159
 160         /* insert ipcomp header and replace datagram */
 161         ipch = ip_comp_hdr(skb);
 162         ipch->nexthdr = *skb_mac_header(skb);
 163         ipch->flags = 0;
 164         ipch->cpi = htons((u16 )ntohl(x->id.spi));
 165         *skb_mac_header(skb) = IPPROTO_COMP;
 166
 167 out_ok:
 168         skb_push(skb, -skb_network_offset(skb));
 169
 170         return 0;
 171 }
 172
 173 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 174                                 int type, int code, int offset, __be32 info)
 175 {
 176         __be32 spi;
 177         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 178         struct ip_comp_hdr *ipcomph =
 179                 (struct ip_comp_hdr *)(skb->data + offset);
 180         struct xfrm_state *x;
 181
 182         if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG)
 183                 return;
 184
 185         spi = htonl(ntohs(ipcomph->cpi));
 186         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6);
 187         if (!x)
 188                 return;
 189
 190         printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIP6_FMT "\n",
 191                         spi, NIP6(iph->daddr));
 192         xfrm_state_put(x);
 193 }
 194
 195 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
 196 {
 197         struct xfrm_state *t = NULL;
 198
 199         t = xfrm_state_alloc();
 200         if (!t)
 201                 goto out;
 202
 203         t->id.proto = IPPROTO_IPV6;
 204         t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);
 205         if (!t->id.spi)
 206                 goto error;
 207
 208         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
 209         memcpy(&t->sel, &x->sel, sizeof(t->sel));
 210         t->props.family = AF_INET6;
 211         t->props.mode = x->props.mode;
 212         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
 213
 214         if (xfrm_init_state(t))
 215                 goto error;
 216
 217         atomic_set(&t->tunnel_users, 1);
 218
 219 out:
 220         return t;
 221
 222 error:
 223         t->km.state = XFRM_STATE_DEAD;
 224         xfrm_state_put(t);
 225         t = NULL;
 226         goto out;
 227 }
 228
 229 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
 230 {
 231         int err = 0;
 232         struct xfrm_state *t = NULL;
 233         __be32 spi;
 234
 235         spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
 236         if (spi)
 237                 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
 238                                               spi, IPPROTO_IPV6, AF_INET6);
 239         if (!t) {
 240                 t = ipcomp6_tunnel_create(x);
 241                 if (!t) {
 242                         err = -EINVAL;
 243                         goto out;
 244                 }
 245                 xfrm_state_insert(t);
 246                 xfrm_state_hold(t);
 247         }
 248         x->tunnel = t;
 249         atomic_inc(&t->tunnel_users);
 250
 251 out:
 252         return err;
 253 }
 254
 255 static void ipcomp6_free_scratches(void)
 256 {
 257         int i;
 258         void **scratches;
 259
 260         if (--ipcomp6_scratch_users)
 261                 return;
 262
 263         scratches = ipcomp6_scratches;
 264         if (!scratches)
 265                 return;
 266
 267         for_each_possible_cpu(i) {
 268                 void *scratch = *per_cpu_ptr(scratches, i);
 269
 270                 vfree(scratch);
 271         }
 272
 273         free_percpu(scratches);
 274 }
 275
 276 static void **ipcomp6_alloc_scratches(void)
 277 {
 278         int i;
 279         void **scratches;
 280
 281         if (ipcomp6_scratch_users++)
 282                 return ipcomp6_scratches;
 283
 284         scratches = alloc_percpu(void *);
 285         if (!scratches)
 286                 return NULL;
 287
 288         ipcomp6_scratches = scratches;
 289
 290         for_each_possible_cpu(i) {
 291                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
 292                 if (!scratch)
 293                         return NULL;
 294                 *per_cpu_ptr(scratches, i) = scratch;
 295         }
 296
 297         return scratches;
 298 }
 299
 300 static void ipcomp6_free_tfms(struct crypto_comp **tfms)
 301 {
 302         struct ipcomp6_tfms *pos;
 303         int cpu;
 304
 305         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 306                 if (pos->tfms == tfms)
 307                         break;
 308         }
 309
 310         BUG_TRAP(pos);
 311
 312         if (--pos->users)
 313                 return;
 314
 315         list_del(&pos->list);
 316         kfree(pos);
 317
 318         if (!tfms)
 319                 return;
 320
 321         for_each_possible_cpu(cpu) {
 322                 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
 323                 crypto_free_comp(tfm);
 324         }
 325         free_percpu(tfms);
 326 }
 327
 328 static struct crypto_comp **ipcomp6_alloc_tfms(const char *alg_name)
 329 {
 330         struct ipcomp6_tfms *pos;
 331         struct crypto_comp **tfms;
 332         int cpu;
 333
 334         /* This can be any valid CPU ID so we don't need locking. */
 335         cpu = raw_smp_processor_id();
 336
 337         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 338                 struct crypto_comp *tfm;
 339
 340                 tfms = pos->tfms;
 341                 tfm = *per_cpu_ptr(tfms, cpu);
 342
 343                 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
 344                         pos->users++;
 345                         return tfms;
 346                 }
 347         }
 348
 349         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
 350         if (!pos)
 351                 return NULL;
 352
 353         pos->users = 1;
 354         INIT_LIST_HEAD(&pos->list);
 355         list_add(&pos->list, &ipcomp6_tfms_list);
 356
 357         pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
 358         if (!tfms)
 359                 goto error;
 360
 361         for_each_possible_cpu(cpu) {
 362                 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
 363                                                             CRYPTO_ALG_ASYNC);
 364                 if (IS_ERR(tfm))
 365                         goto error;
 366                 *per_cpu_ptr(tfms, cpu) = tfm;
 367         }
 368
 369         return tfms;
 370
 371 error:
 372         ipcomp6_free_tfms(tfms);
 373         return NULL;
 374 }
 375
 376 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
 377 {
 378         if (ipcd->tfms)
 379                 ipcomp6_free_tfms(ipcd->tfms);
 380         ipcomp6_free_scratches();
 381 }
 382
 383 static void ipcomp6_destroy(struct xfrm_state *x)
 384 {
 385         struct ipcomp_data *ipcd = x->data;
 386         if (!ipcd)
 387                 return;
 388         xfrm_state_delete_tunnel(x);
 389         mutex_lock(&ipcomp6_resource_mutex);
 390         ipcomp6_free_data(ipcd);
 391         mutex_unlock(&ipcomp6_resource_mutex);
 392         kfree(ipcd);
 393
 394         xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
 395 }
 396
 397 static int ipcomp6_init_state(struct xfrm_state *x)
 398 {
 399         int err;
 400         struct ipcomp_data *ipcd;
 401         struct xfrm_algo_desc *calg_desc;
 402
 403         err = -EINVAL;
 404         if (!x->calg)
 405                 goto out;
 406
 407         if (x->encap)
 408                 goto out;
 409
 410         x->props.header_len = 0;
 411         switch (x->props.mode) {
 412         case XFRM_MODE_TRANSPORT:
 413                 break;
 414         case XFRM_MODE_TUNNEL:
 415                 x->props.header_len += sizeof(struct ipv6hdr);
 416                 break;
 417         default:
 418                 goto out;
 419         }
 420
 421         err = -ENOMEM;
 422         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
 423         if (!ipcd)
 424                 goto out;
 425
 426         mutex_lock(&ipcomp6_resource_mutex);
 427         if (!ipcomp6_alloc_scratches())
 428                 goto error;
 429
 430         ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name);
 431         if (!ipcd->tfms)
 432                 goto error;
 433         mutex_unlock(&ipcomp6_resource_mutex);
 434
 435         if (x->props.mode == XFRM_MODE_TUNNEL) {
 436                 err = ipcomp6_tunnel_attach(x);
 437                 if (err)
 438                         goto error_tunnel;
 439         }
 440
 441         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
 442         BUG_ON(!calg_desc);
 443         ipcd->threshold = calg_desc->uinfo.comp.threshold;
 444         x->data = ipcd;
 445         err = 0;
 446 out:
 447         return err;
 448 error_tunnel:
 449         mutex_lock(&ipcomp6_resource_mutex);
 450 error:
 451         ipcomp6_free_data(ipcd);
 452         mutex_unlock(&ipcomp6_resource_mutex);
 453         kfree(ipcd);
 454
 455         goto out;
 456 }
 457
 458 static const struct xfrm_type ipcomp6_type =
 459 {
 460         .description    = "IPCOMP6",
 461         .owner          = THIS_MODULE,
 462         .proto          = IPPROTO_COMP,
 463         .init_state     = ipcomp6_init_state,
 464         .destructor     = ipcomp6_destroy,
 465         .input          = ipcomp6_input,
 466         .output         = ipcomp6_output,
 467         .hdr_offset     = xfrm6_find_1stfragopt,
 468 };
 469
 470 static struct inet6_protocol ipcomp6_protocol =
 471 {
 472         .handler        = xfrm6_rcv,
 473         .err_handler    = ipcomp6_err,
 474         .flags          = INET6_PROTO_NOPOLICY,
 475 };
 476
 477 static int __init ipcomp6_init(void)
 478 {
 479         if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
 480                 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n");
 481                 return -EAGAIN;
 482         }
 483         if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
 484                 printk(KERN_INFO "ipcomp6 init: can't add protocol\n");
 485                 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
 486                 return -EAGAIN;
 487         }
 488         return 0;
 489 }
 490
 491 static void __exit ipcomp6_fini(void)
 492 {
 493         if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0)
 494                 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n");
 495         if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
 496                 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n");
 497 }
 498
 499 module_init(ipcomp6_init);
 500 module_exit(ipcomp6_fini);
 501 MODULE_LICENSE("GPL");
 502 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
 503 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
 504
 505 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP);