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