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 <linux/crypto.h> 38 #include <linux/err.h> 39 #include <linux/pfkeyv2.h> 40 #include <linux/random.h> 41 #include <linux/percpu.h> 42 #include <linux/smp.h> 43 #include <linux/list.h> 44 #include <linux/vmalloc.h> 45 #include <linux/rtnetlink.h> 46 #include <net/icmp.h> 47 #include <net/ipv6.h> 48 #include <net/protocol.h> 49 #include <linux/ipv6.h> 50 #include <linux/icmpv6.h> 51 #include <linux/mutex.h> 52 53 struct ipcomp6_tfms { 54 struct list_head list; 55 struct crypto_comp **tfms; 56 int users; 57 }; 58 59 static DEFINE_MUTEX(ipcomp6_resource_mutex); 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 sk_buff *skb) 65 { 66 int nexthdr; 67 int err = -ENOMEM; 68 struct ip_comp_hdr *ipch; 69 int plen, dlen; 70 struct ipcomp_data *ipcd = x->data; 71 u8 *start, *scratch; 72 struct crypto_comp *tfm; 73 int cpu; 74 75 if (skb_linearize_cow(skb)) 76 goto out; 77 78 skb->ip_summed = CHECKSUM_NONE; 79 80 /* Remove ipcomp header and decompress original payload */ 81 ipch = (void *)skb->data; 82 nexthdr = ipch->nexthdr; 83 84 skb->transport_header = skb->network_header + 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 goto out_put_cpu; 99 100 if (dlen < (plen + sizeof(*ipch))) { 101 err = -EINVAL; 102 goto out_put_cpu; 103 } 104 105 err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC); 106 if (err) { 107 goto out_put_cpu; 108 } 109 110 skb->truesize += dlen - plen; 111 __skb_put(skb, dlen - plen); 112 skb_copy_to_linear_data(skb, scratch, dlen); 113 err = nexthdr; 114 115 out_put_cpu: 116 put_cpu(); 117 out: 118 return err; 119 } 120 121 static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb) 122 { 123 int err; 124 struct ip_comp_hdr *ipch; 125 struct ipcomp_data *ipcd = x->data; 126 int plen, dlen; 127 u8 *start, *scratch; 128 struct crypto_comp *tfm; 129 int cpu; 130 131 /* check whether datagram len is larger than threshold */ 132 if (skb->len < ipcd->threshold) { 133 goto out_ok; 134 } 135 136 if (skb_linearize_cow(skb)) 137 goto out_ok; 138 139 /* compression */ 140 plen = skb->len; 141 dlen = IPCOMP_SCRATCH_SIZE; 142 start = skb->data; 143 144 cpu = get_cpu(); 145 scratch = *per_cpu_ptr(ipcomp6_scratches, cpu); 146 tfm = *per_cpu_ptr(ipcd->tfms, cpu); 147 148 local_bh_disable(); 149 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen); 150 local_bh_enable(); 151 if (err || (dlen + sizeof(*ipch)) >= plen) { 152 put_cpu(); 153 goto out_ok; 154 } 155 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen); 156 put_cpu(); 157 pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr)); 158 159 /* insert ipcomp header and replace datagram */ 160 ipch = ip_comp_hdr(skb); 161 ipch->nexthdr = *skb_mac_header(skb); 162 ipch->flags = 0; 163 ipch->cpi = htons((u16 )ntohl(x->id.spi)); 164 *skb_mac_header(skb) = IPPROTO_COMP; 165 166 out_ok: 167 skb_push(skb, -skb_network_offset(skb)); 168 169 return 0; 170 } 171 172 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 173 int type, int code, int offset, __be32 info) 174 { 175 __be32 spi; 176 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 177 struct ip_comp_hdr *ipcomph = 178 (struct ip_comp_hdr *)(skb->data + offset); 179 struct xfrm_state *x; 180 181 if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG) 182 return; 183 184 spi = htonl(ntohs(ipcomph->cpi)); 185 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6); 186 if (!x) 187 return; 188 189 printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIP6_FMT "\n", 190 spi, NIP6(iph->daddr)); 191 xfrm_state_put(x); 192 } 193 194 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x) 195 { 196 struct xfrm_state *t = NULL; 197 198 t = xfrm_state_alloc(); 199 if (!t) 200 goto out; 201 202 t->id.proto = IPPROTO_IPV6; 203 t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr); 204 if (!t->id.spi) 205 goto error; 206 207 memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr)); 208 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 209 t->props.family = AF_INET6; 210 t->props.mode = x->props.mode; 211 memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr)); 212 213 if (xfrm_init_state(t)) 214 goto error; 215 216 atomic_set(&t->tunnel_users, 1); 217 218 out: 219 return t; 220 221 error: 222 t->km.state = XFRM_STATE_DEAD; 223 xfrm_state_put(t); 224 t = NULL; 225 goto out; 226 } 227 228 static int ipcomp6_tunnel_attach(struct xfrm_state *x) 229 { 230 int err = 0; 231 struct xfrm_state *t = NULL; 232 __be32 spi; 233 234 spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr); 235 if (spi) 236 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr, 237 spi, IPPROTO_IPV6, AF_INET6); 238 if (!t) { 239 t = ipcomp6_tunnel_create(x); 240 if (!t) { 241 err = -EINVAL; 242 goto out; 243 } 244 xfrm_state_insert(t); 245 xfrm_state_hold(t); 246 } 247 x->tunnel = t; 248 atomic_inc(&t->tunnel_users); 249 250 out: 251 return err; 252 } 253 254 static void ipcomp6_free_scratches(void) 255 { 256 int i; 257 void **scratches; 258 259 if (--ipcomp6_scratch_users) 260 return; 261 262 scratches = ipcomp6_scratches; 263 if (!scratches) 264 return; 265 266 for_each_possible_cpu(i) { 267 void *scratch = *per_cpu_ptr(scratches, i); 268 269 vfree(scratch); 270 } 271 272 free_percpu(scratches); 273 } 274 275 static void **ipcomp6_alloc_scratches(void) 276 { 277 int i; 278 void **scratches; 279 280 if (ipcomp6_scratch_users++) 281 return ipcomp6_scratches; 282 283 scratches = alloc_percpu(void *); 284 if (!scratches) 285 return NULL; 286 287 ipcomp6_scratches = scratches; 288 289 for_each_possible_cpu(i) { 290 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); 291 if (!scratch) 292 return NULL; 293 *per_cpu_ptr(scratches, i) = scratch; 294 } 295 296 return scratches; 297 } 298 299 static void ipcomp6_free_tfms(struct crypto_comp **tfms) 300 { 301 struct ipcomp6_tfms *pos; 302 int cpu; 303 304 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 305 if (pos->tfms == tfms) 306 break; 307 } 308 309 BUG_TRAP(pos); 310 311 if (--pos->users) 312 return; 313 314 list_del(&pos->list); 315 kfree(pos); 316 317 if (!tfms) 318 return; 319 320 for_each_possible_cpu(cpu) { 321 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu); 322 crypto_free_comp(tfm); 323 } 324 free_percpu(tfms); 325 } 326 327 static struct crypto_comp **ipcomp6_alloc_tfms(const char *alg_name) 328 { 329 struct ipcomp6_tfms *pos; 330 struct crypto_comp **tfms; 331 int cpu; 332 333 /* This can be any valid CPU ID so we don't need locking. */ 334 cpu = raw_smp_processor_id(); 335 336 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 337 struct crypto_comp *tfm; 338 339 tfms = pos->tfms; 340 tfm = *per_cpu_ptr(tfms, cpu); 341 342 if (!strcmp(crypto_comp_name(tfm), alg_name)) { 343 pos->users++; 344 return tfms; 345 } 346 } 347 348 pos = kmalloc(sizeof(*pos), GFP_KERNEL); 349 if (!pos) 350 return NULL; 351 352 pos->users = 1; 353 INIT_LIST_HEAD(&pos->list); 354 list_add(&pos->list, &ipcomp6_tfms_list); 355 356 pos->tfms = tfms = alloc_percpu(struct crypto_comp *); 357 if (!tfms) 358 goto error; 359 360 for_each_possible_cpu(cpu) { 361 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0, 362 CRYPTO_ALG_ASYNC); 363 if (IS_ERR(tfm)) 364 goto error; 365 *per_cpu_ptr(tfms, cpu) = tfm; 366 } 367 368 return tfms; 369 370 error: 371 ipcomp6_free_tfms(tfms); 372 return NULL; 373 } 374 375 static void ipcomp6_free_data(struct ipcomp_data *ipcd) 376 { 377 if (ipcd->tfms) 378 ipcomp6_free_tfms(ipcd->tfms); 379 ipcomp6_free_scratches(); 380 } 381 382 static void ipcomp6_destroy(struct xfrm_state *x) 383 { 384 struct ipcomp_data *ipcd = x->data; 385 if (!ipcd) 386 return; 387 xfrm_state_delete_tunnel(x); 388 mutex_lock(&ipcomp6_resource_mutex); 389 ipcomp6_free_data(ipcd); 390 mutex_unlock(&ipcomp6_resource_mutex); 391 kfree(ipcd); 392 393 xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr); 394 } 395 396 static int ipcomp6_init_state(struct xfrm_state *x) 397 { 398 int err; 399 struct ipcomp_data *ipcd; 400 struct xfrm_algo_desc *calg_desc; 401 402 err = -EINVAL; 403 if (!x->calg) 404 goto out; 405 406 if (x->encap) 407 goto out; 408 409 x->props.header_len = 0; 410 switch (x->props.mode) { 411 case XFRM_MODE_TRANSPORT: 412 break; 413 case XFRM_MODE_TUNNEL: 414 x->props.header_len += sizeof(struct ipv6hdr); 415 break; 416 default: 417 goto out; 418 } 419 420 err = -ENOMEM; 421 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL); 422 if (!ipcd) 423 goto out; 424 425 mutex_lock(&ipcomp6_resource_mutex); 426 if (!ipcomp6_alloc_scratches()) 427 goto error; 428 429 ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name); 430 if (!ipcd->tfms) 431 goto error; 432 mutex_unlock(&ipcomp6_resource_mutex); 433 434 if (x->props.mode == XFRM_MODE_TUNNEL) { 435 err = ipcomp6_tunnel_attach(x); 436 if (err) 437 goto error_tunnel; 438 } 439 440 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0); 441 BUG_ON(!calg_desc); 442 ipcd->threshold = calg_desc->uinfo.comp.threshold; 443 x->data = ipcd; 444 err = 0; 445 out: 446 return err; 447 error_tunnel: 448 mutex_lock(&ipcomp6_resource_mutex); 449 error: 450 ipcomp6_free_data(ipcd); 451 mutex_unlock(&ipcomp6_resource_mutex); 452 kfree(ipcd); 453 454 goto out; 455 } 456 457 static const struct xfrm_type ipcomp6_type = 458 { 459 .description = "IPCOMP6", 460 .owner = THIS_MODULE, 461 .proto = IPPROTO_COMP, 462 .init_state = ipcomp6_init_state, 463 .destructor = ipcomp6_destroy, 464 .input = ipcomp6_input, 465 .output = ipcomp6_output, 466 .hdr_offset = xfrm6_find_1stfragopt, 467 }; 468 469 static struct inet6_protocol ipcomp6_protocol = 470 { 471 .handler = xfrm6_rcv, 472 .err_handler = ipcomp6_err, 473 .flags = INET6_PROTO_NOPOLICY, 474 }; 475 476 static int __init ipcomp6_init(void) 477 { 478 if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) { 479 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n"); 480 return -EAGAIN; 481 } 482 if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) { 483 printk(KERN_INFO "ipcomp6 init: can't add protocol\n"); 484 xfrm_unregister_type(&ipcomp6_type, AF_INET6); 485 return -EAGAIN; 486 } 487 return 0; 488 } 489 490 static void __exit ipcomp6_fini(void) 491 { 492 if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) 493 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n"); 494 if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0) 495 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n"); 496 } 497 498 module_init(ipcomp6_init); 499 module_exit(ipcomp6_fini); 500 MODULE_LICENSE("GPL"); 501 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173"); 502 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>"); 503 504 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP); 505