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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 ipv6hdr *iph;
  69         struct ipv6_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         iph = skb->nh.ipv6h;
  83         ipch = (void *)skb->data;
  84         skb->h.raw = skb->nh.raw + 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                 err = -EINVAL;
  99                 goto out_put_cpu;
 100         }
 101
 102         if (dlen < (plen + sizeof(struct ipv6_comp_hdr))) {
 103                 err = -EINVAL;
 104                 goto out_put_cpu;
 105         }
 106
 107         err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
 108         if (err) {
 109                 goto out_put_cpu;
 110         }
 111
 112         skb->truesize += dlen - plen;
 113         __skb_put(skb, dlen - plen);
 114         memcpy(skb->data, scratch, dlen);
 115         err = ipch->nexthdr;
 116
 117 out_put_cpu:
 118         put_cpu();
 119 out:
 120         return err;
 121 }
 122
 123 static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb)
 124 {
 125         int err;
 126         struct ipv6hdr *top_iph;
 127         int hdr_len;
 128         struct ipv6_comp_hdr *ipch;
 129         struct ipcomp_data *ipcd = x->data;
 130         int plen, dlen;
 131         u8 *start, *scratch;
 132         struct crypto_comp *tfm;
 133         int cpu;
 134
 135         hdr_len = skb->h.raw - skb->data;
 136
 137         /* check whether datagram len is larger than threshold */
 138         if ((skb->len - hdr_len) < ipcd->threshold) {
 139                 goto out_ok;
 140         }
 141
 142         if (skb_linearize_cow(skb))
 143                 goto out_ok;
 144
 145         /* compression */
 146         plen = skb->len - hdr_len;
 147         dlen = IPCOMP_SCRATCH_SIZE;
 148         start = skb->h.raw;
 149
 150         cpu = get_cpu();
 151         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
 152         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 153
 154         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
 155         if (err || (dlen + sizeof(struct ipv6_comp_hdr)) >= plen) {
 156                 put_cpu();
 157                 goto out_ok;
 158         }
 159         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
 160         put_cpu();
 161         pskb_trim(skb, hdr_len + dlen + sizeof(struct ip_comp_hdr));
 162
 163         /* insert ipcomp header and replace datagram */
 164         top_iph = (struct ipv6hdr *)skb->data;
 165
 166         top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 167
 168         ipch = (struct ipv6_comp_hdr *)start;
 169         ipch->nexthdr = *skb->nh.raw;
 170         ipch->flags = 0;
 171         ipch->cpi = htons((u16 )ntohl(x->id.spi));
 172         *skb->nh.raw = IPPROTO_COMP;
 173
 174 out_ok:
 175         return 0;
 176 }
 177
 178 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 179                                 int type, int code, int offset, __u32 info)
 180 {
 181         __be32 spi;
 182         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 183         struct ipv6_comp_hdr *ipcomph = (struct ipv6_comp_hdr*)(skb->data+offset);
 184         struct xfrm_state *x;
 185
 186         if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG)
 187                 return;
 188
 189         spi = htonl(ntohs(ipcomph->cpi));
 190         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6);
 191         if (!x)
 192                 return;
 193
 194         printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIP6_FMT "\n",
 195                         spi, NIP6(iph->daddr));
 196         xfrm_state_put(x);
 197 }
 198
 199 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
 200 {
 201         struct xfrm_state *t = NULL;
 202         u8 mode = XFRM_MODE_TUNNEL;
 203
 204         t = xfrm_state_alloc();
 205         if (!t)
 206                 goto out;
 207
 208         t->id.proto = IPPROTO_IPV6;
 209         t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);
 210         if (!t->id.spi)
 211                 goto error;
 212
 213         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
 214         memcpy(&t->sel, &x->sel, sizeof(t->sel));
 215         t->props.family = AF_INET6;
 216         if (x->props.mode == XFRM_MODE_BEET)
 217                 mode = x->props.mode;
 218         t->props.mode = mode;
 219         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
 220
 221         if (xfrm_init_state(t))
 222                 goto error;
 223
 224         atomic_set(&t->tunnel_users, 1);
 225
 226 out:
 227         return t;
 228
 229 error:
 230         t->km.state = XFRM_STATE_DEAD;
 231         xfrm_state_put(t);
 232         t = NULL;
 233         goto out;
 234 }
 235
 236 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
 237 {
 238         int err = 0;
 239         struct xfrm_state *t = NULL;
 240         __be32 spi;
 241
 242         spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
 243         if (spi)
 244                 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
 245                                               spi, IPPROTO_IPV6, AF_INET6);
 246         if (!t) {
 247                 t = ipcomp6_tunnel_create(x);
 248                 if (!t) {
 249                         err = -EINVAL;
 250                         goto out;
 251                 }
 252                 xfrm_state_insert(t);
 253                 xfrm_state_hold(t);
 254         }
 255         x->tunnel = t;
 256         atomic_inc(&t->tunnel_users);
 257
 258 out:
 259         return err;
 260 }
 261
 262 static void ipcomp6_free_scratches(void)
 263 {
 264         int i;
 265         void **scratches;
 266
 267         if (--ipcomp6_scratch_users)
 268                 return;
 269
 270         scratches = ipcomp6_scratches;
 271         if (!scratches)
 272                 return;
 273
 274         for_each_possible_cpu(i) {
 275                 void *scratch = *per_cpu_ptr(scratches, i);
 276
 277                 vfree(scratch);
 278         }
 279
 280         free_percpu(scratches);
 281 }
 282
 283 static void **ipcomp6_alloc_scratches(void)
 284 {
 285         int i;
 286         void **scratches;
 287
 288         if (ipcomp6_scratch_users++)
 289                 return ipcomp6_scratches;
 290
 291         scratches = alloc_percpu(void *);
 292         if (!scratches)
 293                 return NULL;
 294
 295         ipcomp6_scratches = scratches;
 296
 297         for_each_possible_cpu(i) {
 298                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
 299                 if (!scratch)
 300                         return NULL;
 301                 *per_cpu_ptr(scratches, i) = scratch;
 302         }
 303
 304         return scratches;
 305 }
 306
 307 static void ipcomp6_free_tfms(struct crypto_comp **tfms)
 308 {
 309         struct ipcomp6_tfms *pos;
 310         int cpu;
 311
 312         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 313                 if (pos->tfms == tfms)
 314                         break;
 315         }
 316
 317         BUG_TRAP(pos);
 318
 319         if (--pos->users)
 320                 return;
 321
 322         list_del(&pos->list);
 323         kfree(pos);
 324
 325         if (!tfms)
 326                 return;
 327
 328         for_each_possible_cpu(cpu) {
 329                 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
 330                 crypto_free_comp(tfm);
 331         }
 332         free_percpu(tfms);
 333 }
 334
 335 static struct crypto_comp **ipcomp6_alloc_tfms(const char *alg_name)
 336 {
 337         struct ipcomp6_tfms *pos;
 338         struct crypto_comp **tfms;
 339         int cpu;
 340
 341         /* This can be any valid CPU ID so we don't need locking. */
 342         cpu = raw_smp_processor_id();
 343
 344         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 345                 struct crypto_comp *tfm;
 346
 347                 tfms = pos->tfms;
 348                 tfm = *per_cpu_ptr(tfms, cpu);
 349
 350                 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
 351                         pos->users++;
 352                         return tfms;
 353                 }
 354         }
 355
 356         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
 357         if (!pos)
 358                 return NULL;
 359
 360         pos->users = 1;
 361         INIT_LIST_HEAD(&pos->list);
 362         list_add(&pos->list, &ipcomp6_tfms_list);
 363
 364         pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
 365         if (!tfms)
 366                 goto error;
 367
 368         for_each_possible_cpu(cpu) {
 369                 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
 370                                                             CRYPTO_ALG_ASYNC);
 371                 if (!tfm)
 372                         goto error;
 373                 *per_cpu_ptr(tfms, cpu) = tfm;
 374         }
 375
 376         return tfms;
 377
 378 error:
 379         ipcomp6_free_tfms(tfms);
 380         return NULL;
 381 }
 382
 383 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
 384 {
 385         if (ipcd->tfms)
 386                 ipcomp6_free_tfms(ipcd->tfms);
 387         ipcomp6_free_scratches();
 388 }
 389
 390 static void ipcomp6_destroy(struct xfrm_state *x)
 391 {
 392         struct ipcomp_data *ipcd = x->data;
 393         if (!ipcd)
 394                 return;
 395         xfrm_state_delete_tunnel(x);
 396         mutex_lock(&ipcomp6_resource_mutex);
 397         ipcomp6_free_data(ipcd);
 398         mutex_unlock(&ipcomp6_resource_mutex);
 399         kfree(ipcd);
 400
 401         xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
 402 }
 403
 404 static int ipcomp6_init_state(struct xfrm_state *x)
 405 {
 406         int err;
 407         struct ipcomp_data *ipcd;
 408         struct xfrm_algo_desc *calg_desc;
 409
 410         err = -EINVAL;
 411         if (!x->calg)
 412                 goto out;
 413
 414         if (x->encap)
 415                 goto out;
 416
 417         err = -ENOMEM;
 418         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
 419         if (!ipcd)
 420                 goto out;
 421
 422         x->props.header_len = 0;
 423         if (x->props.mode == XFRM_MODE_TUNNEL)
 424                 x->props.header_len += sizeof(struct ipv6hdr);
 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 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