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