net/ipv6/ipcomp6.c

   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 sk_buff *skb)
 143 {
 144         int err;
 145         struct dst_entry *dst = skb->dst;
 146         struct xfrm_state *x = dst->xfrm;
 147         struct ipv6hdr *top_iph;
 148         int hdr_len;
 149         struct ipv6_comp_hdr *ipch;
 150         struct ipcomp_data *ipcd = x->data;
 151         int plen, dlen;
 152         u8 *start, *scratch;
 153         struct crypto_tfm *tfm;
 154         int cpu;
 155
 156         hdr_len = skb->h.raw - skb->data;
 157
 158         /* check whether datagram len is larger than threshold */
 159         if ((skb->len - hdr_len) < ipcd->threshold) {
 160                 goto out_ok;
 161         }
 162
 163         if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
 164                 skb_linearize(skb, GFP_ATOMIC) != 0) {
 165                 err = -ENOMEM;
 166                 goto error;
 167         }
 168
 169         /* compression */
 170         plen = skb->len - hdr_len;
 171         dlen = IPCOMP_SCRATCH_SIZE;
 172         start = skb->h.raw;
 173
 174         cpu = get_cpu();
 175         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
 176         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 177
 178         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
 179         if (err) {
 180                 put_cpu();
 181                 goto error;
 182         }
 183         if ((dlen + sizeof(struct ipv6_comp_hdr)) >= plen) {
 184                 put_cpu();
 185                 goto out_ok;
 186         }
 187         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
 188         put_cpu();
 189         pskb_trim(skb, hdr_len + dlen + sizeof(struct ip_comp_hdr));
 190
 191         /* insert ipcomp header and replace datagram */
 192         top_iph = (struct ipv6hdr *)skb->data;
 193
 194         top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 195
 196         ipch = (struct ipv6_comp_hdr *)start;
 197         ipch->nexthdr = *skb->nh.raw;
 198         ipch->flags = 0;
 199         ipch->cpi = htons((u16 )ntohl(x->id.spi));
 200         *skb->nh.raw = IPPROTO_COMP;
 201
 202 out_ok:
 203         err = 0;
 204
 205 error:
 206         return err;
 207 }
 208
 209 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 210                                 int type, int code, int offset, __u32 info)
 211 {
 212         u32 spi;
 213         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
 214         struct ipv6_comp_hdr *ipcomph = (struct ipv6_comp_hdr*)(skb->data+offset);
 215         struct xfrm_state *x;
 216
 217         if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG)
 218                 return;
 219
 220         spi = ntohl(ntohs(ipcomph->cpi));
 221         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6);
 222         if (!x)
 223                 return;
 224
 225         printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/"
 226                         "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n",
 227                         spi, NIP6(iph->daddr));
 228         xfrm_state_put(x);
 229 }
 230
 231 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
 232 {
 233         struct xfrm_state *t = NULL;
 234
 235         t = xfrm_state_alloc();
 236         if (!t)
 237                 goto out;
 238
 239         t->id.proto = IPPROTO_IPV6;
 240         t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);
 241         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
 242         memcpy(&t->sel, &x->sel, sizeof(t->sel));
 243         t->props.family = AF_INET6;
 244         t->props.mode = 1;
 245         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
 246
 247         t->type = xfrm_get_type(IPPROTO_IPV6, t->props.family);
 248         if (t->type == NULL)
 249                 goto error;
 250
 251         if (t->type->init_state(t, NULL))
 252                 goto error;
 253
 254         t->km.state = XFRM_STATE_VALID;
 255         atomic_set(&t->tunnel_users, 1);
 256
 257 out:
 258         return t;
 259
 260 error:
 261         xfrm_state_put(t);
 262         goto out;
 263 }
 264
 265 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
 266 {
 267         int err = 0;
 268         struct xfrm_state *t = NULL;
 269         u32 spi;
 270
 271         spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
 272         if (spi)
 273                 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
 274                                               spi, IPPROTO_IPV6, AF_INET6);
 275         if (!t) {
 276                 t = ipcomp6_tunnel_create(x);
 277                 if (!t) {
 278                         err = -EINVAL;
 279                         goto out;
 280                 }
 281                 xfrm_state_insert(t);
 282                 xfrm_state_hold(t);
 283         }
 284         x->tunnel = t;
 285         atomic_inc(&t->tunnel_users);
 286
 287 out:
 288         return err;
 289 }
 290
 291 static void ipcomp6_free_scratches(void)
 292 {
 293         int i;
 294         void **scratches;
 295
 296         if (--ipcomp6_scratch_users)
 297                 return;
 298
 299         scratches = ipcomp6_scratches;
 300         if (!scratches)
 301                 return;
 302
 303         for_each_cpu(i) {
 304                 void *scratch = *per_cpu_ptr(scratches, i);
 305                 if (scratch)
 306                         vfree(scratch);
 307         }
 308
 309         free_percpu(scratches);
 310 }
 311
 312 static void **ipcomp6_alloc_scratches(void)
 313 {
 314         int i;
 315         void **scratches;
 316
 317         if (ipcomp6_scratch_users++)
 318                 return ipcomp6_scratches;
 319
 320         scratches = alloc_percpu(void *);
 321         if (!scratches)
 322                 return NULL;
 323
 324         ipcomp6_scratches = scratches;
 325
 326         for_each_cpu(i) {
 327                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
 328                 if (!scratch)
 329                         return NULL;
 330                 *per_cpu_ptr(scratches, i) = scratch;
 331         }
 332
 333         return scratches;
 334 }
 335
 336 static void ipcomp6_free_tfms(struct crypto_tfm **tfms)
 337 {
 338         struct ipcomp6_tfms *pos;
 339         int cpu;
 340
 341         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 342                 if (pos->tfms == tfms)
 343                         break;
 344         }
 345
 346         BUG_TRAP(pos);
 347
 348         if (--pos->users)
 349                 return;
 350
 351         list_del(&pos->list);
 352         kfree(pos);
 353
 354         if (!tfms)
 355                 return;
 356
 357         for_each_cpu(cpu) {
 358                 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu);
 359                 if (tfm)
 360                         crypto_free_tfm(tfm);
 361         }
 362         free_percpu(tfms);
 363 }
 364
 365 static struct crypto_tfm **ipcomp6_alloc_tfms(const char *alg_name)
 366 {
 367         struct ipcomp6_tfms *pos;
 368         struct crypto_tfm **tfms;
 369         int cpu;
 370
 371         /* This can be any valid CPU ID so we don't need locking. */
 372         cpu = smp_processor_id();
 373
 374         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
 375                 struct crypto_tfm *tfm;
 376
 377                 tfms = pos->tfms;
 378                 tfm = *per_cpu_ptr(tfms, cpu);
 379
 380                 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) {
 381                         pos->users++;
 382                         return tfms;
 383                 }
 384         }
 385
 386         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
 387         if (!pos)
 388                 return NULL;
 389
 390         pos->users = 1;
 391         INIT_LIST_HEAD(&pos->list);
 392         list_add(&pos->list, &ipcomp6_tfms_list);
 393
 394         pos->tfms = tfms = alloc_percpu(struct crypto_tfm *);
 395         if (!tfms)
 396                 goto error;
 397
 398         for_each_cpu(cpu) {
 399                 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0);
 400                 if (!tfm)
 401                         goto error;
 402                 *per_cpu_ptr(tfms, cpu) = tfm;
 403         }
 404
 405         return tfms;
 406
 407 error:
 408         ipcomp6_free_tfms(tfms);
 409         return NULL;
 410 }
 411
 412 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
 413 {
 414         if (ipcd->tfms)
 415                 ipcomp6_free_tfms(ipcd->tfms);
 416         ipcomp6_free_scratches();
 417 }
 418
 419 static void ipcomp6_destroy(struct xfrm_state *x)
 420 {
 421         struct ipcomp_data *ipcd = x->data;
 422         if (!ipcd)
 423                 return;
 424         xfrm_state_delete_tunnel(x);
 425         down(&ipcomp6_resource_sem);
 426         ipcomp6_free_data(ipcd);
 427         up(&ipcomp6_resource_sem);
 428         kfree(ipcd);
 429
 430         xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
 431 }
 432
 433 static int ipcomp6_init_state(struct xfrm_state *x, void *args)
 434 {
 435         int err;
 436         struct ipcomp_data *ipcd;
 437         struct xfrm_algo_desc *calg_desc;
 438
 439         err = -EINVAL;
 440         if (!x->calg)
 441                 goto out;
 442
 443         if (x->encap)
 444                 goto out;
 445
 446         err = -ENOMEM;
 447         ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL);
 448         if (!ipcd)
 449                 goto out;
 450
 451         memset(ipcd, 0, sizeof(*ipcd));
 452         x->props.header_len = 0;
 453         if (x->props.mode)
 454                 x->props.header_len += sizeof(struct ipv6hdr);
 455
 456         down(&ipcomp6_resource_sem);
 457         if (!ipcomp6_alloc_scratches())
 458                 goto error;
 459
 460         ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name);
 461         if (!ipcd->tfms)
 462                 goto error;
 463         up(&ipcomp6_resource_sem);
 464
 465         if (x->props.mode) {
 466                 err = ipcomp6_tunnel_attach(x);
 467                 if (err)
 468                         goto error_tunnel;
 469         }
 470
 471         calg_desc = xfrm_calg_get_byname(x->calg->alg_name);
 472         BUG_ON(!calg_desc);
 473         ipcd->threshold = calg_desc->uinfo.comp.threshold;
 474         x->data = ipcd;
 475         err = 0;
 476 out:
 477         return err;
 478 error_tunnel:
 479         down(&ipcomp6_resource_sem);
 480 error:
 481         ipcomp6_free_data(ipcd);
 482         up(&ipcomp6_resource_sem);
 483         kfree(ipcd);
 484
 485         goto out;
 486 }
 487
 488 static struct xfrm_type ipcomp6_type =
 489 {
 490         .description    = "IPCOMP6",
 491         .owner          = THIS_MODULE,
 492         .proto          = IPPROTO_COMP,
 493         .init_state     = ipcomp6_init_state,
 494         .destructor     = ipcomp6_destroy,
 495         .input          = ipcomp6_input,
 496         .output         = ipcomp6_output,
 497 };
 498
 499 static struct inet6_protocol ipcomp6_protocol =
 500 {
 501         .handler        = xfrm6_rcv,
 502         .err_handler    = ipcomp6_err,
 503         .flags          = INET6_PROTO_NOPOLICY,
 504 };
 505
 506 static int __init ipcomp6_init(void)
 507 {
 508         if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
 509                 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n");
 510                 return -EAGAIN;
 511         }
 512         if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
 513                 printk(KERN_INFO "ipcomp6 init: can't add protocol\n");
 514                 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
 515                 return -EAGAIN;
 516         }
 517         return 0;
 518 }
 519
 520 static void __exit ipcomp6_fini(void)
 521 {
 522         if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0)
 523                 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n");
 524         if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
 525                 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n");
 526 }
 527
 528 module_init(ipcomp6_init);
 529 module_exit(ipcomp6_fini);
 530 MODULE_LICENSE("GPL");
 531 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
 532 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
 533
 534