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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         kfree(tmp_hdr);
 134         if (err)
 135                 goto error_out;
 136         return nexthdr;
 137 error_out:
 138         return err;
 139 }
 140
 141 static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb)
 142 {
 143         int err;
 144         struct ipv6hdr *top_iph;
 145         int hdr_len;
 146         struct ipv6_comp_hdr *ipch;
 147         struct ipcomp_data *ipcd = x->data;
 148         int plen, dlen;
 149         u8 *start, *scratch;
 150         struct crypto_tfm *tfm;
 151         int cpu;
 152
 153         hdr_len = skb->h.raw - skb->data;
 154
 155         /* check whether datagram len is larger than threshold */
 156         if ((skb->len - hdr_len) < ipcd->threshold) {
 157                 goto out_ok;
 158         }
 159
 160         if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
 161                 skb_linearize(skb, GFP_ATOMIC) != 0) {
 162                 goto out_ok;
 163         }
 164
 165         /* compression */
 166         plen = skb->len - hdr_len;
 167         dlen = IPCOMP_SCRATCH_SIZE;
 168         start = skb->h.raw;
 169
 170         cpu = get_cpu();
 171         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
 172         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 173
 174         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
 175         if (err || (dlen + sizeof(struct ipv6_comp_hdr)) >= plen) {
 176                 put_cpu();
 177                 goto out_ok;
 178         }
 179         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
 180         put_cpu();
 181         pskb_trim(skb, hdr_len + dlen + sizeof(struct ip_comp_hdr));
 182
 183         /* insert ipcomp header and replace datagram */
 184         top_iph = (struct ipv6hdr *)skb->data;
 185
 186         top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 187
 188         ipch = (struct ipv6_comp_hdr *)start;
 189         ipch->nexthdr = *skb->nh.raw;
 190         ipch->flags = 0;
 191         ipch->cpi = htons((u16 )ntohl(x->id.spi));
 192         *skb->nh.raw = IPPROTO_COMP;
 193
 194 out_ok:
 195         return 0;
 196 }
 197
 198 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 199                                 int type, int code, int offset, __u32 info)
 200 {
 201         u32 spi;
 202         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 203         struct ipv6_comp_hdr *ipcomph = (struct ipv6_comp_hdr*)(skb->data+offset);
 204         struct xfrm_state *x;
 205
 206         if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG)
 207                 return;
 208
 209         spi = ntohl(ntohs(ipcomph->cpi));
 210         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6);
 211         if (!x)
 212                 return;
 213
 214         printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/"
 215                         "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n",
 216                         spi, NIP6(iph->daddr));
 217         xfrm_state_put(x);
 218 }
 219
 220 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
 221 {
 222         struct xfrm_state *t = NULL;
 223
 224         t = xfrm_state_alloc();
 225         if (!t)
 226                 goto out;
 227
 228         t->id.proto = IPPROTO_IPV6;
 229         t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);
 230         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
 231         memcpy(&t->sel, &x->sel, sizeof(t->sel));
 232         t->props.family = AF_INET6;
 233         t->props.mode = 1;
 234         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
 235
 236         if (xfrm_init_state(t))
 237                 goto error;
 238
 239         atomic_set(&t->tunnel_users, 1);
 240
 241 out:
 242         return t;
 243
 244 error:
 245         xfrm_state_put(t);
 246         goto out;
 247 }
 248
 249 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
 250 {
 251         int err = 0;
 252         struct xfrm_state *t = NULL;
 253         u32 spi;
 254
 255         spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
 256         if (spi)
 257                 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
 258                                               spi, IPPROTO_IPV6, AF_INET6);
 259         if (!t) {
 260                 t = ipcomp6_tunnel_create(x);
 261                 if (!t) {
 262                         err = -EINVAL;
 263                         goto out;
 264                 }
 265                 xfrm_state_insert(t);
 266                 xfrm_state_hold(t);
 267         }
 268         x->tunnel = t;
 269         atomic_inc(&t->tunnel_users);
 270
 271 out:
 272         return err;
 273 }
 274
 275 static void ipcomp6_free_scratches(void)
 276 {
 277         int i;
 278         void **scratches;
 279
 280         if (--ipcomp6_scratch_users)
 281                 return;
 282
 283         scratches = ipcomp6_scratches;
 284         if (!scratches)
 285                 return;
 286
 287         for_each_cpu(i) {
 288                 void *scratch = *per_cpu_ptr(scratches, i);
 289                 if (scratch)
 290                         vfree(scratch);
 291         }
 292
 293         free_percpu(scratches);
 294 }
 295
 296 static void **ipcomp6_alloc_scratches(void)
 297 {
 298         int i;
 299         void **scratches;
 300
 301         if (ipcomp6_scratch_users++)
 302                 return ipcomp6_scratches;
 303
 304         scratches = alloc_percpu(void *);
 305         if (!scratches)
 306                 return NULL;
 307
 308         ipcomp6_scratches = scratches;
 309
 310         for_each_cpu(i) {
 311                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
 312                 if (!scratch)
 313                         return NULL;
 314                 *per_cpu_ptr(scratches, i) = scratch;
 315         }
 316
 317         return scratches;
 318 }
 319
 320 static void ipcomp6_free_tfms(struct crypto_tfm **tfms)
 321 {
 322         struct ipcomp6_tfms *pos;
 323         int cpu;
 324
 325         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 326                 if (pos->tfms == tfms)
 327                         break;
 328         }
 329
 330         BUG_TRAP(pos);
 331
 332         if (--pos->users)
 333                 return;
 334
 335         list_del(&pos->list);
 336         kfree(pos);
 337
 338         if (!tfms)
 339                 return;
 340
 341         for_each_cpu(cpu) {
 342                 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu);
 343                 crypto_free_tfm(tfm);
 344         }
 345         free_percpu(tfms);
 346 }
 347
 348 static struct crypto_tfm **ipcomp6_alloc_tfms(const char *alg_name)
 349 {
 350         struct ipcomp6_tfms *pos;
 351         struct crypto_tfm **tfms;
 352         int cpu;
 353
 354         /* This can be any valid CPU ID so we don't need locking. */
 355         cpu = raw_smp_processor_id();
 356
 357         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 358                 struct crypto_tfm *tfm;
 359
 360                 tfms = pos->tfms;
 361                 tfm = *per_cpu_ptr(tfms, cpu);
 362
 363                 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) {
 364                         pos->users++;
 365                         return tfms;
 366                 }
 367         }
 368
 369         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
 370         if (!pos)
 371                 return NULL;
 372
 373         pos->users = 1;
 374         INIT_LIST_HEAD(&pos->list);
 375         list_add(&pos->list, &ipcomp6_tfms_list);
 376
 377         pos->tfms = tfms = alloc_percpu(struct crypto_tfm *);
 378         if (!tfms)
 379                 goto error;
 380
 381         for_each_cpu(cpu) {
 382                 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0);
 383                 if (!tfm)
 384                         goto error;
 385                 *per_cpu_ptr(tfms, cpu) = tfm;
 386         }
 387
 388         return tfms;
 389
 390 error:
 391         ipcomp6_free_tfms(tfms);
 392         return NULL;
 393 }
 394
 395 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
 396 {
 397         if (ipcd->tfms)
 398                 ipcomp6_free_tfms(ipcd->tfms);
 399         ipcomp6_free_scratches();
 400 }
 401
 402 static void ipcomp6_destroy(struct xfrm_state *x)
 403 {
 404         struct ipcomp_data *ipcd = x->data;
 405         if (!ipcd)
 406                 return;
 407         xfrm_state_delete_tunnel(x);
 408         down(&ipcomp6_resource_sem);
 409         ipcomp6_free_data(ipcd);
 410         up(&ipcomp6_resource_sem);
 411         kfree(ipcd);
 412
 413         xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
 414 }
 415
 416 static int ipcomp6_init_state(struct xfrm_state *x)
 417 {
 418         int err;
 419         struct ipcomp_data *ipcd;
 420         struct xfrm_algo_desc *calg_desc;
 421
 422         err = -EINVAL;
 423         if (!x->calg)
 424                 goto out;
 425
 426         if (x->encap)
 427                 goto out;
 428
 429         err = -ENOMEM;
 430         ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL);
 431         if (!ipcd)
 432                 goto out;
 433
 434         memset(ipcd, 0, sizeof(*ipcd));
 435         x->props.header_len = 0;
 436         if (x->props.mode)
 437                 x->props.header_len += sizeof(struct ipv6hdr);
 438
 439         down(&ipcomp6_resource_sem);
 440         if (!ipcomp6_alloc_scratches())
 441                 goto error;
 442
 443         ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name);
 444         if (!ipcd->tfms)
 445                 goto error;
 446         up(&ipcomp6_resource_sem);
 447
 448         if (x->props.mode) {
 449                 err = ipcomp6_tunnel_attach(x);
 450                 if (err)
 451                         goto error_tunnel;
 452         }
 453
 454         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
 455         BUG_ON(!calg_desc);
 456         ipcd->threshold = calg_desc->uinfo.comp.threshold;
 457         x->data = ipcd;
 458         err = 0;
 459 out:
 460         return err;
 461 error_tunnel:
 462         down(&ipcomp6_resource_sem);
 463 error:
 464         ipcomp6_free_data(ipcd);
 465         up(&ipcomp6_resource_sem);
 466         kfree(ipcd);
 467
 468         goto out;
 469 }
 470
 471 static struct xfrm_type ipcomp6_type =
 472 {
 473         .description    = "IPCOMP6",
 474         .owner          = THIS_MODULE,
 475         .proto          = IPPROTO_COMP,
 476         .init_state     = ipcomp6_init_state,
 477         .destructor     = ipcomp6_destroy,
 478         .input          = ipcomp6_input,
 479         .output         = ipcomp6_output,
 480 };
 481
 482 static struct inet6_protocol ipcomp6_protocol =
 483 {
 484         .handler        = xfrm6_rcv,
 485         .err_handler    = ipcomp6_err,
 486         .flags          = INET6_PROTO_NOPOLICY,
 487 };
 488
 489 static int __init ipcomp6_init(void)
 490 {
 491         if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
 492                 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n");
 493                 return -EAGAIN;
 494         }
 495         if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
 496                 printk(KERN_INFO "ipcomp6 init: can't add protocol\n");
 497                 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
 498                 return -EAGAIN;
 499         }
 500         return 0;
 501 }
 502
 503 static void __exit ipcomp6_fini(void)
 504 {
 505         if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0)
 506                 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n");
 507         if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
 508                 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n");
 509 }
 510
 511 module_init(ipcomp6_init);
 512 module_exit(ipcomp6_fini);
 513 MODULE_LICENSE("GPL");
 514 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
 515 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
 516
 517