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