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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 <linux/ipv6.h>
  51 #include <linux/icmpv6.h>
  52
  53 struct ipcomp6_tfms {
  54         struct list_head list;
  55         struct crypto_tfm **tfms;
  56         int users;
  57 };
  58
  59 static DECLARE_MUTEX(ipcomp6_resource_sem);
  60 static void **ipcomp6_scratches;
  61 static int ipcomp6_scratch_users;
  62 static LIST_HEAD(ipcomp6_tfms_list);
  63
  64 static int ipcomp6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb)
  65 {
  66         int err = 0;
  67         u8 nexthdr = 0;
  68         int hdr_len = skb->h.raw - skb->nh.raw;
  69         unsigned char *tmp_hdr = NULL;
  70         struct ipv6hdr *iph;
  71         int plen, dlen;
  72         struct ipcomp_data *ipcd = x->data;
  73         u8 *start, *scratch;
  74         struct crypto_tfm *tfm;
  75         int cpu;
  76
  77         if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
  78                 skb_linearize(skb, GFP_ATOMIC) != 0) {
  79                 err = -ENOMEM;
  80                 goto out;
  81         }
  82
  83         skb->ip_summed = CHECKSUM_NONE;
  84
  85         /* Remove ipcomp header and decompress original payload */
  86         iph = skb->nh.ipv6h;
  87         tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC);
  88         if (!tmp_hdr)
  89                 goto out;
  90         memcpy(tmp_hdr, iph, hdr_len);
  91         nexthdr = *(u8 *)skb->data;
  92         skb_pull(skb, sizeof(struct ipv6_comp_hdr));
  93         skb->nh.raw += sizeof(struct ipv6_comp_hdr);
  94         memcpy(skb->nh.raw, tmp_hdr, hdr_len);
  95         iph = skb->nh.ipv6h;
  96         iph->payload_len = htons(ntohs(iph->payload_len) - sizeof(struct ipv6_comp_hdr));
  97         skb->h.raw = skb->data;
  98
  99         /* decompression */
 100         plen = skb->len;
 101         dlen = IPCOMP_SCRATCH_SIZE;
 102         start = skb->data;
 103
 104         cpu = get_cpu();
 105         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
 106         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 107
 108         err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
 109         if (err) {
 110                 err = -EINVAL;
 111                 goto out_put_cpu;
 112         }
 113
 114         if (dlen < (plen + sizeof(struct ipv6_comp_hdr))) {
 115                 err = -EINVAL;
 116                 goto out_put_cpu;
 117         }
 118
 119         err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
 120         if (err) {
 121                 goto out_put_cpu;
 122         }
 123
 124         skb_put(skb, dlen - plen);
 125         memcpy(skb->data, scratch, dlen);
 126
 127         iph = skb->nh.ipv6h;
 128         iph->payload_len = htons(skb->len);
 129
 130 out_put_cpu:
 131         put_cpu();
 132 out:
 133         if (tmp_hdr)
 134                 kfree(tmp_hdr);
 135         if (err)
 136                 goto error_out;
 137         return nexthdr;
 138 error_out:
 139         return err;
 140 }
 141
 142 static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb)
 143 {
 144         int err;
 145         struct ipv6hdr *top_iph;
 146         int hdr_len;
 147         struct ipv6_comp_hdr *ipch;
 148         struct ipcomp_data *ipcd = x->data;
 149         int plen, dlen;
 150         u8 *start, *scratch;
 151         struct crypto_tfm *tfm;
 152         int cpu;
 153
 154         hdr_len = skb->h.raw - skb->data;
 155
 156         /* check whether datagram len is larger than threshold */
 157         if ((skb->len - hdr_len) < ipcd->threshold) {
 158                 goto out_ok;
 159         }
 160
 161         if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
 162                 skb_linearize(skb, GFP_ATOMIC) != 0) {
 163                 goto out_ok;
 164         }
 165
 166         /* compression */
 167         plen = skb->len - hdr_len;
 168         dlen = IPCOMP_SCRATCH_SIZE;
 169         start = skb->h.raw;
 170
 171         cpu = get_cpu();
 172         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
 173         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 174
 175         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
 176         if (err || (dlen + sizeof(struct ipv6_comp_hdr)) >= plen) {
 177                 put_cpu();
 178                 goto out_ok;
 179         }
 180         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
 181         put_cpu();
 182         pskb_trim(skb, hdr_len + dlen + sizeof(struct ip_comp_hdr));
 183
 184         /* insert ipcomp header and replace datagram */
 185         top_iph = (struct ipv6hdr *)skb->data;
 186
 187         top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 188
 189         ipch = (struct ipv6_comp_hdr *)start;
 190         ipch->nexthdr = *skb->nh.raw;
 191         ipch->flags = 0;
 192         ipch->cpi = htons((u16 )ntohl(x->id.spi));
 193         *skb->nh.raw = IPPROTO_COMP;
 194
 195 out_ok:
 196         return 0;
 197 }
 198
 199 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 200                                 int type, int code, int offset, __u32 info)
 201 {
 202         u32 spi;
 203         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 204         struct ipv6_comp_hdr *ipcomph = (struct ipv6_comp_hdr*)(skb->data+offset);
 205         struct xfrm_state *x;
 206
 207         if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG)
 208                 return;
 209
 210         spi = ntohl(ntohs(ipcomph->cpi));
 211         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6);
 212         if (!x)
 213                 return;
 214
 215         printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/"
 216                         "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\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         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
 232         memcpy(&t->sel, &x->sel, sizeof(t->sel));
 233         t->props.family = AF_INET6;
 234         t->props.mode = 1;
 235         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
 236
 237         if (xfrm_init_state(t))
 238                 goto error;
 239
 240         atomic_set(&t->tunnel_users, 1);
 241
 242 out:
 243         return t;
 244
 245 error:
 246         xfrm_state_put(t);
 247         goto out;
 248 }
 249
 250 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
 251 {
 252         int err = 0;
 253         struct xfrm_state *t = NULL;
 254         u32 spi;
 255
 256         spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
 257         if (spi)
 258                 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
 259                                               spi, IPPROTO_IPV6, AF_INET6);
 260         if (!t) {
 261                 t = ipcomp6_tunnel_create(x);
 262                 if (!t) {
 263                         err = -EINVAL;
 264                         goto out;
 265                 }
 266                 xfrm_state_insert(t);
 267                 xfrm_state_hold(t);
 268         }
 269         x->tunnel = t;
 270         atomic_inc(&t->tunnel_users);
 271
 272 out:
 273         return err;
 274 }
 275
 276 static void ipcomp6_free_scratches(void)
 277 {
 278         int i;
 279         void **scratches;
 280
 281         if (--ipcomp6_scratch_users)
 282                 return;
 283
 284         scratches = ipcomp6_scratches;
 285         if (!scratches)
 286                 return;
 287
 288         for_each_cpu(i) {
 289                 void *scratch = *per_cpu_ptr(scratches, i);
 290                 if (scratch)
 291                         vfree(scratch);
 292         }
 293
 294         free_percpu(scratches);
 295 }
 296
 297 static void **ipcomp6_alloc_scratches(void)
 298 {
 299         int i;
 300         void **scratches;
 301
 302         if (ipcomp6_scratch_users++)
 303                 return ipcomp6_scratches;
 304
 305         scratches = alloc_percpu(void *);
 306         if (!scratches)
 307                 return NULL;
 308
 309         ipcomp6_scratches = scratches;
 310
 311         for_each_cpu(i) {
 312                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
 313                 if (!scratch)
 314                         return NULL;
 315                 *per_cpu_ptr(scratches, i) = scratch;
 316         }
 317
 318         return scratches;
 319 }
 320
 321 static void ipcomp6_free_tfms(struct crypto_tfm **tfms)
 322 {
 323         struct ipcomp6_tfms *pos;
 324         int cpu;
 325
 326         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 327                 if (pos->tfms == tfms)
 328                         break;
 329         }
 330
 331         BUG_TRAP(pos);
 332
 333         if (--pos->users)
 334                 return;
 335
 336         list_del(&pos->list);
 337         kfree(pos);
 338
 339         if (!tfms)
 340                 return;
 341
 342         for_each_cpu(cpu) {
 343                 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu);
 344                 if (tfm)
 345                         crypto_free_tfm(tfm);
 346         }
 347         free_percpu(tfms);
 348 }
 349
 350 static struct crypto_tfm **ipcomp6_alloc_tfms(const char *alg_name)
 351 {
 352         struct ipcomp6_tfms *pos;
 353         struct crypto_tfm **tfms;
 354         int cpu;
 355
 356         /* This can be any valid CPU ID so we don't need locking. */
 357         cpu = raw_smp_processor_id();
 358
 359         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 360                 struct crypto_tfm *tfm;
 361
 362                 tfms = pos->tfms;
 363                 tfm = *per_cpu_ptr(tfms, cpu);
 364
 365                 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) {
 366                         pos->users++;
 367                         return tfms;
 368                 }
 369         }
 370
 371         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
 372         if (!pos)
 373                 return NULL;
 374
 375         pos->users = 1;
 376         INIT_LIST_HEAD(&pos->list);
 377         list_add(&pos->list, &ipcomp6_tfms_list);
 378
 379         pos->tfms = tfms = alloc_percpu(struct crypto_tfm *);
 380         if (!tfms)
 381                 goto error;
 382
 383         for_each_cpu(cpu) {
 384                 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0);
 385                 if (!tfm)
 386                         goto error;
 387                 *per_cpu_ptr(tfms, cpu) = tfm;
 388         }
 389
 390         return tfms;
 391
 392 error:
 393         ipcomp6_free_tfms(tfms);
 394         return NULL;
 395 }
 396
 397 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
 398 {
 399         if (ipcd->tfms)
 400                 ipcomp6_free_tfms(ipcd->tfms);
 401         ipcomp6_free_scratches();
 402 }
 403
 404 static void ipcomp6_destroy(struct xfrm_state *x)
 405 {
 406         struct ipcomp_data *ipcd = x->data;
 407         if (!ipcd)
 408                 return;
 409         xfrm_state_delete_tunnel(x);
 410         down(&ipcomp6_resource_sem);
 411         ipcomp6_free_data(ipcd);
 412         up(&ipcomp6_resource_sem);
 413         kfree(ipcd);
 414
 415         xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
 416 }
 417
 418 static int ipcomp6_init_state(struct xfrm_state *x)
 419 {
 420         int err;
 421         struct ipcomp_data *ipcd;
 422         struct xfrm_algo_desc *calg_desc;
 423
 424         err = -EINVAL;
 425         if (!x->calg)
 426                 goto out;
 427
 428         if (x->encap)
 429                 goto out;
 430
 431         err = -ENOMEM;
 432         ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL);
 433         if (!ipcd)
 434                 goto out;
 435
 436         memset(ipcd, 0, sizeof(*ipcd));
 437         x->props.header_len = 0;
 438         if (x->props.mode)
 439                 x->props.header_len += sizeof(struct ipv6hdr);
 440
 441         down(&ipcomp6_resource_sem);
 442         if (!ipcomp6_alloc_scratches())
 443                 goto error;
 444
 445         ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name);
 446         if (!ipcd->tfms)
 447                 goto error;
 448         up(&ipcomp6_resource_sem);
 449
 450         if (x->props.mode) {
 451                 err = ipcomp6_tunnel_attach(x);
 452                 if (err)
 453                         goto error_tunnel;
 454         }
 455
 456         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
 457         BUG_ON(!calg_desc);
 458         ipcd->threshold = calg_desc->uinfo.comp.threshold;
 459         x->data = ipcd;
 460         err = 0;
 461 out:
 462         return err;
 463 error_tunnel:
 464         down(&ipcomp6_resource_sem);
 465 error:
 466         ipcomp6_free_data(ipcd);
 467         up(&ipcomp6_resource_sem);
 468         kfree(ipcd);
 469
 470         goto out;
 471 }
 472
 473 static struct xfrm_type ipcomp6_type =
 474 {
 475         .description    = "IPCOMP6",
 476         .owner          = THIS_MODULE,
 477         .proto          = IPPROTO_COMP,
 478         .init_state     = ipcomp6_init_state,
 479         .destructor     = ipcomp6_destroy,
 480         .input          = ipcomp6_input,
 481         .output         = ipcomp6_output,
 482 };
 483
 484 static struct inet6_protocol ipcomp6_protocol =
 485 {
 486         .handler        = xfrm6_rcv,
 487         .err_handler    = ipcomp6_err,
 488         .flags          = INET6_PROTO_NOPOLICY,
 489 };
 490
 491 static int __init ipcomp6_init(void)
 492 {
 493         if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
 494                 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n");
 495                 return -EAGAIN;
 496         }
 497         if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
 498                 printk(KERN_INFO "ipcomp6 init: can't add protocol\n");
 499                 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
 500                 return -EAGAIN;
 501         }
 502         return 0;
 503 }
 504
 505 static void __exit ipcomp6_fini(void)
 506 {
 507         if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0)
 508                 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n");
 509         if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
 510                 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n");
 511 }
 512
 513 module_init(ipcomp6_init);
 514 module_exit(ipcomp6_fini);
 515 MODULE_LICENSE("GPL");
 516 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
 517 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
 518
 519