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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/config.h>
  34 #include <linux/module.h>
  35 #include <net/ip.h>
  36 #include <net/xfrm.h>
  37 #include <net/ipcomp.h>
  38 #include <asm/scatterlist.h>
  39 #include <asm/semaphore.h>
  40 #include <linux/crypto.h>
  41 #include <linux/pfkeyv2.h>
  42 #include <linux/random.h>
  43 #include <linux/percpu.h>
  44 #include <linux/smp.h>
  45 #include <linux/list.h>
  46 #include <linux/vmalloc.h>
  47 #include <linux/rtnetlink.h>
  48 #include <net/icmp.h>
  49 #include <net/ipv6.h>
  50 #include <net/protocol.h>
  51 #include <linux/ipv6.h>
  52 #include <linux/icmpv6.h>
  53 #include <linux/mutex.h>
  54
  55 struct ipcomp6_tfms {
  56         struct list_head list;
  57         struct crypto_tfm **tfms;
  58         int users;
  59 };
  60
  61 static DEFINE_MUTEX(ipcomp6_resource_mutex);
  62 static void **ipcomp6_scratches;
  63 static int ipcomp6_scratch_users;
  64 static LIST_HEAD(ipcomp6_tfms_list);
  65
  66 static int ipcomp6_input(struct xfrm_state *x, struct sk_buff *skb)
  67 {
  68         int err = 0;
  69         u8 nexthdr = 0;
  70         int hdr_len = skb->h.raw - skb->nh.raw;
  71         unsigned char *tmp_hdr = NULL;
  72         struct ipv6hdr *iph;
  73         int plen, dlen;
  74         struct ipcomp_data *ipcd = x->data;
  75         u8 *start, *scratch;
  76         struct crypto_tfm *tfm;
  77         int cpu;
  78
  79         if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
  80                 skb_linearize(skb, GFP_ATOMIC) != 0) {
  81                 err = -ENOMEM;
  82                 goto out;
  83         }
  84
  85         skb->ip_summed = CHECKSUM_NONE;
  86
  87         /* Remove ipcomp header and decompress original payload */
  88         iph = skb->nh.ipv6h;
  89         tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC);
  90         if (!tmp_hdr)
  91                 goto out;
  92         memcpy(tmp_hdr, iph, hdr_len);
  93         nexthdr = *(u8 *)skb->data;
  94         skb_pull(skb, sizeof(struct ipv6_comp_hdr));
  95         skb->nh.raw += sizeof(struct ipv6_comp_hdr);
  96         memcpy(skb->nh.raw, tmp_hdr, hdr_len);
  97         iph = skb->nh.ipv6h;
  98         iph->payload_len = htons(ntohs(iph->payload_len) - sizeof(struct ipv6_comp_hdr));
  99         skb->h.raw = skb->data;
 100
 101         /* decompression */
 102         plen = skb->len;
 103         dlen = IPCOMP_SCRATCH_SIZE;
 104         start = skb->data;
 105
 106         cpu = get_cpu();
 107         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
 108         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 109
 110         err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
 111         if (err) {
 112                 err = -EINVAL;
 113                 goto out_put_cpu;
 114         }
 115
 116         if (dlen < (plen + sizeof(struct ipv6_comp_hdr))) {
 117                 err = -EINVAL;
 118                 goto out_put_cpu;
 119         }
 120
 121         err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
 122         if (err) {
 123                 goto out_put_cpu;
 124         }
 125
 126         skb_put(skb, dlen - plen);
 127         memcpy(skb->data, scratch, dlen);
 128
 129         iph = skb->nh.ipv6h;
 130         iph->payload_len = htons(skb->len);
 131
 132 out_put_cpu:
 133         put_cpu();
 134 out:
 135         kfree(tmp_hdr);
 136         if (err)
 137                 goto error_out;
 138         return nexthdr;
 139 error_out:
 140         return err;
 141 }
 142
 143 static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb)
 144 {
 145         int err;
 146         struct ipv6hdr *top_iph;
 147         int hdr_len;
 148         struct ipv6_comp_hdr *ipch;
 149         struct ipcomp_data *ipcd = x->data;
 150         int plen, dlen;
 151         u8 *start, *scratch;
 152         struct crypto_tfm *tfm;
 153         int cpu;
 154
 155         hdr_len = skb->h.raw - skb->data;
 156
 157         /* check whether datagram len is larger than threshold */
 158         if ((skb->len - hdr_len) < ipcd->threshold) {
 159                 goto out_ok;
 160         }
 161
 162         if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
 163                 skb_linearize(skb, GFP_ATOMIC) != 0) {
 164                 goto out_ok;
 165         }
 166
 167         /* compression */
 168         plen = skb->len - hdr_len;
 169         dlen = IPCOMP_SCRATCH_SIZE;
 170         start = skb->h.raw;
 171
 172         cpu = get_cpu();
 173         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
 174         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 175
 176         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
 177         if (err || (dlen + sizeof(struct ipv6_comp_hdr)) >= plen) {
 178                 put_cpu();
 179                 goto out_ok;
 180         }
 181         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
 182         put_cpu();
 183         pskb_trim(skb, hdr_len + dlen + sizeof(struct ip_comp_hdr));
 184
 185         /* insert ipcomp header and replace datagram */
 186         top_iph = (struct ipv6hdr *)skb->data;
 187
 188         top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 189
 190         ipch = (struct ipv6_comp_hdr *)start;
 191         ipch->nexthdr = *skb->nh.raw;
 192         ipch->flags = 0;
 193         ipch->cpi = htons((u16 )ntohl(x->id.spi));
 194         *skb->nh.raw = IPPROTO_COMP;
 195
 196 out_ok:
 197         return 0;
 198 }
 199
 200 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 201                                 int type, int code, int offset, __u32 info)
 202 {
 203         u32 spi;
 204         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 205         struct ipv6_comp_hdr *ipcomph = (struct ipv6_comp_hdr*)(skb->data+offset);
 206         struct xfrm_state *x;
 207
 208         if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG)
 209                 return;
 210
 211         spi = htonl(ntohs(ipcomph->cpi));
 212         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6);
 213         if (!x)
 214                 return;
 215
 216         printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIP6_FMT "\n",
 217                         spi, NIP6(iph->daddr));
 218         xfrm_state_put(x);
 219 }
 220
 221 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
 222 {
 223         struct xfrm_state *t = NULL;
 224
 225         t = xfrm_state_alloc();
 226         if (!t)
 227                 goto out;
 228
 229         t->id.proto = IPPROTO_IPV6;
 230         t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);
 231         if (!t->id.spi)
 232                 goto error;
 233
 234         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
 235         memcpy(&t->sel, &x->sel, sizeof(t->sel));
 236         t->props.family = AF_INET6;
 237         t->props.mode = 1;
 238         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
 239
 240         if (xfrm_init_state(t))
 241                 goto error;
 242
 243         atomic_set(&t->tunnel_users, 1);
 244
 245 out:
 246         return t;
 247
 248 error:
 249         t->km.state = XFRM_STATE_DEAD;
 250         xfrm_state_put(t);
 251         t = NULL;
 252         goto out;
 253 }
 254
 255 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
 256 {
 257         int err = 0;
 258         struct xfrm_state *t = NULL;
 259         u32 spi;
 260
 261         spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
 262         if (spi)
 263                 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
 264                                               spi, IPPROTO_IPV6, AF_INET6);
 265         if (!t) {
 266                 t = ipcomp6_tunnel_create(x);
 267                 if (!t) {
 268                         err = -EINVAL;
 269                         goto out;
 270                 }
 271                 xfrm_state_insert(t);
 272                 xfrm_state_hold(t);
 273         }
 274         x->tunnel = t;
 275         atomic_inc(&t->tunnel_users);
 276
 277 out:
 278         return err;
 279 }
 280
 281 static void ipcomp6_free_scratches(void)
 282 {
 283         int i;
 284         void **scratches;
 285
 286         if (--ipcomp6_scratch_users)
 287                 return;
 288
 289         scratches = ipcomp6_scratches;
 290         if (!scratches)
 291                 return;
 292
 293         for_each_possible_cpu(i) {
 294                 void *scratch = *per_cpu_ptr(scratches, i);
 295
 296                 vfree(scratch);
 297         }
 298
 299         free_percpu(scratches);
 300 }
 301
 302 static void **ipcomp6_alloc_scratches(void)
 303 {
 304         int i;
 305         void **scratches;
 306
 307         if (ipcomp6_scratch_users++)
 308                 return ipcomp6_scratches;
 309
 310         scratches = alloc_percpu(void *);
 311         if (!scratches)
 312                 return NULL;
 313
 314         ipcomp6_scratches = scratches;
 315
 316         for_each_possible_cpu(i) {
 317                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
 318                 if (!scratch)
 319                         return NULL;
 320                 *per_cpu_ptr(scratches, i) = scratch;
 321         }
 322
 323         return scratches;
 324 }
 325
 326 static void ipcomp6_free_tfms(struct crypto_tfm **tfms)
 327 {
 328         struct ipcomp6_tfms *pos;
 329         int cpu;
 330
 331         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 332                 if (pos->tfms == tfms)
 333                         break;
 334         }
 335
 336         BUG_TRAP(pos);
 337
 338         if (--pos->users)
 339                 return;
 340
 341         list_del(&pos->list);
 342         kfree(pos);
 343
 344         if (!tfms)
 345                 return;
 346
 347         for_each_possible_cpu(cpu) {
 348                 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu);
 349                 crypto_free_tfm(tfm);
 350         }
 351         free_percpu(tfms);
 352 }
 353
 354 static struct crypto_tfm **ipcomp6_alloc_tfms(const char *alg_name)
 355 {
 356         struct ipcomp6_tfms *pos;
 357         struct crypto_tfm **tfms;
 358         int cpu;
 359
 360         /* This can be any valid CPU ID so we don't need locking. */
 361         cpu = raw_smp_processor_id();
 362
 363         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 364                 struct crypto_tfm *tfm;
 365
 366                 tfms = pos->tfms;
 367                 tfm = *per_cpu_ptr(tfms, cpu);
 368
 369                 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) {
 370                         pos->users++;
 371                         return tfms;
 372                 }
 373         }
 374
 375         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
 376         if (!pos)
 377                 return NULL;
 378
 379         pos->users = 1;
 380         INIT_LIST_HEAD(&pos->list);
 381         list_add(&pos->list, &ipcomp6_tfms_list);
 382
 383         pos->tfms = tfms = alloc_percpu(struct crypto_tfm *);
 384         if (!tfms)
 385                 goto error;
 386
 387         for_each_possible_cpu(cpu) {
 388                 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0);
 389                 if (!tfm)
 390                         goto error;
 391                 *per_cpu_ptr(tfms, cpu) = tfm;
 392         }
 393
 394         return tfms;
 395
 396 error:
 397         ipcomp6_free_tfms(tfms);
 398         return NULL;
 399 }
 400
 401 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
 402 {
 403         if (ipcd->tfms)
 404                 ipcomp6_free_tfms(ipcd->tfms);
 405         ipcomp6_free_scratches();
 406 }
 407
 408 static void ipcomp6_destroy(struct xfrm_state *x)
 409 {
 410         struct ipcomp_data *ipcd = x->data;
 411         if (!ipcd)
 412                 return;
 413         xfrm_state_delete_tunnel(x);
 414         mutex_lock(&ipcomp6_resource_mutex);
 415         ipcomp6_free_data(ipcd);
 416         mutex_unlock(&ipcomp6_resource_mutex);
 417         kfree(ipcd);
 418
 419         xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
 420 }
 421
 422 static int ipcomp6_init_state(struct xfrm_state *x)
 423 {
 424         int err;
 425         struct ipcomp_data *ipcd;
 426         struct xfrm_algo_desc *calg_desc;
 427
 428         err = -EINVAL;
 429         if (!x->calg)
 430                 goto out;
 431
 432         if (x->encap)
 433                 goto out;
 434
 435         err = -ENOMEM;
 436         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
 437         if (!ipcd)
 438                 goto out;
 439
 440         x->props.header_len = 0;
 441         if (x->props.mode)
 442                 x->props.header_len += sizeof(struct ipv6hdr);
 443
 444         mutex_lock(&ipcomp6_resource_mutex);
 445         if (!ipcomp6_alloc_scratches())
 446                 goto error;
 447
 448         ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name);
 449         if (!ipcd->tfms)
 450                 goto error;
 451         mutex_unlock(&ipcomp6_resource_mutex);
 452
 453         if (x->props.mode) {
 454                 err = ipcomp6_tunnel_attach(x);
 455                 if (err)
 456                         goto error_tunnel;
 457         }
 458
 459         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
 460         BUG_ON(!calg_desc);
 461         ipcd->threshold = calg_desc->uinfo.comp.threshold;
 462         x->data = ipcd;
 463         err = 0;
 464 out:
 465         return err;
 466 error_tunnel:
 467         mutex_lock(&ipcomp6_resource_mutex);
 468 error:
 469         ipcomp6_free_data(ipcd);
 470         mutex_unlock(&ipcomp6_resource_mutex);
 471         kfree(ipcd);
 472
 473         goto out;
 474 }
 475
 476 static struct xfrm_type ipcomp6_type =
 477 {
 478         .description    = "IPCOMP6",
 479         .owner          = THIS_MODULE,
 480         .proto          = IPPROTO_COMP,
 481         .init_state     = ipcomp6_init_state,
 482         .destructor     = ipcomp6_destroy,
 483         .input          = ipcomp6_input,
 484         .output         = ipcomp6_output,
 485 };
 486
 487 static struct inet6_protocol ipcomp6_protocol =
 488 {
 489         .handler        = xfrm6_rcv,
 490         .err_handler    = ipcomp6_err,
 491         .flags          = INET6_PROTO_NOPOLICY,
 492 };
 493
 494 static int __init ipcomp6_init(void)
 495 {
 496         if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
 497                 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n");
 498                 return -EAGAIN;
 499         }
 500         if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
 501                 printk(KERN_INFO "ipcomp6 init: can't add protocol\n");
 502                 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
 503                 return -EAGAIN;
 504         }
 505         return 0;
 506 }
 507
 508 static void __exit ipcomp6_fini(void)
 509 {
 510         if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0)
 511                 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n");
 512         if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
 513                 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n");
 514 }
 515
 516 module_init(ipcomp6_init);
 517 module_exit(ipcomp6_fini);
 518 MODULE_LICENSE("GPL");
 519 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
 520 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
 521
 522