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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         struct ipv6hdr *iph;
  70         struct ipv6_comp_hdr *ipch;
  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         ipch = (void *)skb->data;
  88         skb->h.raw = skb->nh.raw + sizeof(*ipch);
  89         __skb_pull(skb, sizeof(*ipch));
  90
  91         /* decompression */
  92         plen = skb->len;
  93         dlen = IPCOMP_SCRATCH_SIZE;
  94         start = skb->data;
  95
  96         cpu = get_cpu();
  97         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
  98         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
  99
 100         err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
 101         if (err) {
 102                 err = -EINVAL;
 103                 goto out_put_cpu;
 104         }
 105
 106         if (dlen < (plen + sizeof(struct ipv6_comp_hdr))) {
 107                 err = -EINVAL;
 108                 goto out_put_cpu;
 109         }
 110
 111         err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
 112         if (err) {
 113                 goto out_put_cpu;
 114         }
 115
 116         skb_put(skb, dlen - plen);
 117         memcpy(skb->data, scratch, dlen);
 118         err = ipch->nexthdr;
 119
 120 out_put_cpu:
 121         put_cpu();
 122 out:
 123         return err;
 124 }
 125
 126 static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb)
 127 {
 128         int err;
 129         struct ipv6hdr *top_iph;
 130         int hdr_len;
 131         struct ipv6_comp_hdr *ipch;
 132         struct ipcomp_data *ipcd = x->data;
 133         int plen, dlen;
 134         u8 *start, *scratch;
 135         struct crypto_tfm *tfm;
 136         int cpu;
 137
 138         hdr_len = skb->h.raw - skb->data;
 139
 140         /* check whether datagram len is larger than threshold */
 141         if ((skb->len - hdr_len) < ipcd->threshold) {
 142                 goto out_ok;
 143         }
 144
 145         if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
 146                 skb_linearize(skb, GFP_ATOMIC) != 0) {
 147                 goto out_ok;
 148         }
 149
 150         /* compression */
 151         plen = skb->len - hdr_len;
 152         dlen = IPCOMP_SCRATCH_SIZE;
 153         start = skb->h.raw;
 154
 155         cpu = get_cpu();
 156         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
 157         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 158
 159         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
 160         if (err || (dlen + sizeof(struct ipv6_comp_hdr)) >= plen) {
 161                 put_cpu();
 162                 goto out_ok;
 163         }
 164         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
 165         put_cpu();
 166         pskb_trim(skb, hdr_len + dlen + sizeof(struct ip_comp_hdr));
 167
 168         /* insert ipcomp header and replace datagram */
 169         top_iph = (struct ipv6hdr *)skb->data;
 170
 171         top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 172
 173         ipch = (struct ipv6_comp_hdr *)start;
 174         ipch->nexthdr = *skb->nh.raw;
 175         ipch->flags = 0;
 176         ipch->cpi = htons((u16 )ntohl(x->id.spi));
 177         *skb->nh.raw = IPPROTO_COMP;
 178
 179 out_ok:
 180         return 0;
 181 }
 182
 183 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 184                                 int type, int code, int offset, __u32 info)
 185 {
 186         u32 spi;
 187         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 188         struct ipv6_comp_hdr *ipcomph = (struct ipv6_comp_hdr*)(skb->data+offset);
 189         struct xfrm_state *x;
 190
 191         if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG)
 192                 return;
 193
 194         spi = htonl(ntohs(ipcomph->cpi));
 195         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6);
 196         if (!x)
 197                 return;
 198
 199         printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIP6_FMT "\n",
 200                         spi, NIP6(iph->daddr));
 201         xfrm_state_put(x);
 202 }
 203
 204 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
 205 {
 206         struct xfrm_state *t = NULL;
 207
 208         t = xfrm_state_alloc();
 209         if (!t)
 210                 goto out;
 211
 212         t->id.proto = IPPROTO_IPV6;
 213         t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);
 214         if (!t->id.spi)
 215                 goto error;
 216
 217         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
 218         memcpy(&t->sel, &x->sel, sizeof(t->sel));
 219         t->props.family = AF_INET6;
 220         t->props.mode = 1;
 221         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
 222
 223         if (xfrm_init_state(t))
 224                 goto error;
 225
 226         atomic_set(&t->tunnel_users, 1);
 227
 228 out:
 229         return t;
 230
 231 error:
 232         t->km.state = XFRM_STATE_DEAD;
 233         xfrm_state_put(t);
 234         t = NULL;
 235         goto out;
 236 }
 237
 238 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
 239 {
 240         int err = 0;
 241         struct xfrm_state *t = NULL;
 242         u32 spi;
 243
 244         spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
 245         if (spi)
 246                 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
 247                                               spi, IPPROTO_IPV6, AF_INET6);
 248         if (!t) {
 249                 t = ipcomp6_tunnel_create(x);
 250                 if (!t) {
 251                         err = -EINVAL;
 252                         goto out;
 253                 }
 254                 xfrm_state_insert(t);
 255                 xfrm_state_hold(t);
 256         }
 257         x->tunnel = t;
 258         atomic_inc(&t->tunnel_users);
 259
 260 out:
 261         return err;
 262 }
 263
 264 static void ipcomp6_free_scratches(void)
 265 {
 266         int i;
 267         void **scratches;
 268
 269         if (--ipcomp6_scratch_users)
 270                 return;
 271
 272         scratches = ipcomp6_scratches;
 273         if (!scratches)
 274                 return;
 275
 276         for_each_possible_cpu(i) {
 277                 void *scratch = *per_cpu_ptr(scratches, i);
 278
 279                 vfree(scratch);
 280         }
 281
 282         free_percpu(scratches);
 283 }
 284
 285 static void **ipcomp6_alloc_scratches(void)
 286 {
 287         int i;
 288         void **scratches;
 289
 290         if (ipcomp6_scratch_users++)
 291                 return ipcomp6_scratches;
 292
 293         scratches = alloc_percpu(void *);
 294         if (!scratches)
 295                 return NULL;
 296
 297         ipcomp6_scratches = scratches;
 298
 299         for_each_possible_cpu(i) {
 300                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
 301                 if (!scratch)
 302                         return NULL;
 303                 *per_cpu_ptr(scratches, i) = scratch;
 304         }
 305
 306         return scratches;
 307 }
 308
 309 static void ipcomp6_free_tfms(struct crypto_tfm **tfms)
 310 {
 311         struct ipcomp6_tfms *pos;
 312         int cpu;
 313
 314         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 315                 if (pos->tfms == tfms)
 316                         break;
 317         }
 318
 319         BUG_TRAP(pos);
 320
 321         if (--pos->users)
 322                 return;
 323
 324         list_del(&pos->list);
 325         kfree(pos);
 326
 327         if (!tfms)
 328                 return;
 329
 330         for_each_possible_cpu(cpu) {
 331                 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu);
 332                 crypto_free_tfm(tfm);
 333         }
 334         free_percpu(tfms);
 335 }
 336
 337 static struct crypto_tfm **ipcomp6_alloc_tfms(const char *alg_name)
 338 {
 339         struct ipcomp6_tfms *pos;
 340         struct crypto_tfm **tfms;
 341         int cpu;
 342
 343         /* This can be any valid CPU ID so we don't need locking. */
 344         cpu = raw_smp_processor_id();
 345
 346         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 347                 struct crypto_tfm *tfm;
 348
 349                 tfms = pos->tfms;
 350                 tfm = *per_cpu_ptr(tfms, cpu);
 351
 352                 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) {
 353                         pos->users++;
 354                         return tfms;
 355                 }
 356         }
 357
 358         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
 359         if (!pos)
 360                 return NULL;
 361
 362         pos->users = 1;
 363         INIT_LIST_HEAD(&pos->list);
 364         list_add(&pos->list, &ipcomp6_tfms_list);
 365
 366         pos->tfms = tfms = alloc_percpu(struct crypto_tfm *);
 367         if (!tfms)
 368                 goto error;
 369
 370         for_each_possible_cpu(cpu) {
 371                 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0);
 372                 if (!tfm)
 373                         goto error;
 374                 *per_cpu_ptr(tfms, cpu) = tfm;
 375         }
 376
 377         return tfms;
 378
 379 error:
 380         ipcomp6_free_tfms(tfms);
 381         return NULL;
 382 }
 383
 384 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
 385 {
 386         if (ipcd->tfms)
 387                 ipcomp6_free_tfms(ipcd->tfms);
 388         ipcomp6_free_scratches();
 389 }
 390
 391 static void ipcomp6_destroy(struct xfrm_state *x)
 392 {
 393         struct ipcomp_data *ipcd = x->data;
 394         if (!ipcd)
 395                 return;
 396         xfrm_state_delete_tunnel(x);
 397         mutex_lock(&ipcomp6_resource_mutex);
 398         ipcomp6_free_data(ipcd);
 399         mutex_unlock(&ipcomp6_resource_mutex);
 400         kfree(ipcd);
 401
 402         xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
 403 }
 404
 405 static int ipcomp6_init_state(struct xfrm_state *x)
 406 {
 407         int err;
 408         struct ipcomp_data *ipcd;
 409         struct xfrm_algo_desc *calg_desc;
 410
 411         err = -EINVAL;
 412         if (!x->calg)
 413                 goto out;
 414
 415         if (x->encap)
 416                 goto out;
 417
 418         err = -ENOMEM;
 419         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
 420         if (!ipcd)
 421                 goto out;
 422
 423         x->props.header_len = 0;
 424         if (x->props.mode)
 425                 x->props.header_len += sizeof(struct ipv6hdr);
 426
 427         mutex_lock(&ipcomp6_resource_mutex);
 428         if (!ipcomp6_alloc_scratches())
 429                 goto error;
 430
 431         ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name);
 432         if (!ipcd->tfms)
 433                 goto error;
 434         mutex_unlock(&ipcomp6_resource_mutex);
 435
 436         if (x->props.mode) {
 437                 err = ipcomp6_tunnel_attach(x);
 438                 if (err)
 439                         goto error_tunnel;
 440         }
 441
 442         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
 443         BUG_ON(!calg_desc);
 444         ipcd->threshold = calg_desc->uinfo.comp.threshold;
 445         x->data = ipcd;
 446         err = 0;
 447 out:
 448         return err;
 449 error_tunnel:
 450         mutex_lock(&ipcomp6_resource_mutex);
 451 error:
 452         ipcomp6_free_data(ipcd);
 453         mutex_unlock(&ipcomp6_resource_mutex);
 454         kfree(ipcd);
 455
 456         goto out;
 457 }
 458
 459 static struct xfrm_type ipcomp6_type =
 460 {
 461         .description    = "IPCOMP6",
 462         .owner          = THIS_MODULE,
 463         .proto          = IPPROTO_COMP,
 464         .init_state     = ipcomp6_init_state,
 465         .destructor     = ipcomp6_destroy,
 466         .input          = ipcomp6_input,
 467         .output         = ipcomp6_output,
 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