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_comp **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_comp *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 = ipv6_hdr(skb); 83 ipch = (void *)skb->data; 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 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->truesize += dlen - plen; 113 __skb_put(skb, dlen - plen); 114 skb_copy_to_linear_data(skb, 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 struct ipv6_comp_hdr *ipch; 128 struct ipcomp_data *ipcd = x->data; 129 int plen, dlen; 130 u8 *start, *scratch; 131 struct crypto_comp *tfm; 132 int cpu; 133 int hdr_len = skb_transport_offset(skb); 134 135 /* check whether datagram len is larger than threshold */ 136 if ((skb->len - hdr_len) < ipcd->threshold) { 137 goto out_ok; 138 } 139 140 if (skb_linearize_cow(skb)) 141 goto out_ok; 142 143 /* compression */ 144 plen = skb->len - hdr_len; 145 dlen = IPCOMP_SCRATCH_SIZE; 146 start = skb_transport_header(skb); 147 148 cpu = get_cpu(); 149 scratch = *per_cpu_ptr(ipcomp6_scratches, cpu); 150 tfm = *per_cpu_ptr(ipcd->tfms, cpu); 151 152 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen); 153 if (err || (dlen + sizeof(struct ipv6_comp_hdr)) >= plen) { 154 put_cpu(); 155 goto out_ok; 156 } 157 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen); 158 put_cpu(); 159 pskb_trim(skb, hdr_len + dlen + sizeof(struct ip_comp_hdr)); 160 161 /* insert ipcomp header and replace datagram */ 162 top_iph = (struct ipv6hdr *)skb->data; 163 164 top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr)); 165 166 ipch = (struct ipv6_comp_hdr *)start; 167 ipch->nexthdr = *skb_network_header(skb); 168 ipch->flags = 0; 169 ipch->cpi = htons((u16 )ntohl(x->id.spi)); 170 *skb_network_header(skb) = IPPROTO_COMP; 171 172 out_ok: 173 return 0; 174 } 175 176 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 177 int type, int code, int offset, __be32 info) 178 { 179 __be32 spi; 180 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 181 struct ipv6_comp_hdr *ipcomph = (struct ipv6_comp_hdr*)(skb->data+offset); 182 struct xfrm_state *x; 183 184 if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG) 185 return; 186 187 spi = htonl(ntohs(ipcomph->cpi)); 188 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6); 189 if (!x) 190 return; 191 192 printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIP6_FMT "\n", 193 spi, NIP6(iph->daddr)); 194 xfrm_state_put(x); 195 } 196 197 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x) 198 { 199 struct xfrm_state *t = NULL; 200 u8 mode = XFRM_MODE_TUNNEL; 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 if (x->props.mode == XFRM_MODE_BEET) 215 mode = x->props.mode; 216 t->props.mode = mode; 217 memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr)); 218 219 if (xfrm_init_state(t)) 220 goto error; 221 222 atomic_set(&t->tunnel_users, 1); 223 224 out: 225 return t; 226 227 error: 228 t->km.state = XFRM_STATE_DEAD; 229 xfrm_state_put(t); 230 t = NULL; 231 goto out; 232 } 233 234 static int ipcomp6_tunnel_attach(struct xfrm_state *x) 235 { 236 int err = 0; 237 struct xfrm_state *t = NULL; 238 __be32 spi; 239 240 spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr); 241 if (spi) 242 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr, 243 spi, IPPROTO_IPV6, AF_INET6); 244 if (!t) { 245 t = ipcomp6_tunnel_create(x); 246 if (!t) { 247 err = -EINVAL; 248 goto out; 249 } 250 xfrm_state_insert(t); 251 xfrm_state_hold(t); 252 } 253 x->tunnel = t; 254 atomic_inc(&t->tunnel_users); 255 256 out: 257 return err; 258 } 259 260 static void ipcomp6_free_scratches(void) 261 { 262 int i; 263 void **scratches; 264 265 if (--ipcomp6_scratch_users) 266 return; 267 268 scratches = ipcomp6_scratches; 269 if (!scratches) 270 return; 271 272 for_each_possible_cpu(i) { 273 void *scratch = *per_cpu_ptr(scratches, i); 274 275 vfree(scratch); 276 } 277 278 free_percpu(scratches); 279 } 280 281 static void **ipcomp6_alloc_scratches(void) 282 { 283 int i; 284 void **scratches; 285 286 if (ipcomp6_scratch_users++) 287 return ipcomp6_scratches; 288 289 scratches = alloc_percpu(void *); 290 if (!scratches) 291 return NULL; 292 293 ipcomp6_scratches = scratches; 294 295 for_each_possible_cpu(i) { 296 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); 297 if (!scratch) 298 return NULL; 299 *per_cpu_ptr(scratches, i) = scratch; 300 } 301 302 return scratches; 303 } 304 305 static void ipcomp6_free_tfms(struct crypto_comp **tfms) 306 { 307 struct ipcomp6_tfms *pos; 308 int cpu; 309 310 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 311 if (pos->tfms == tfms) 312 break; 313 } 314 315 BUG_TRAP(pos); 316 317 if (--pos->users) 318 return; 319 320 list_del(&pos->list); 321 kfree(pos); 322 323 if (!tfms) 324 return; 325 326 for_each_possible_cpu(cpu) { 327 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu); 328 crypto_free_comp(tfm); 329 } 330 free_percpu(tfms); 331 } 332 333 static struct crypto_comp **ipcomp6_alloc_tfms(const char *alg_name) 334 { 335 struct ipcomp6_tfms *pos; 336 struct crypto_comp **tfms; 337 int cpu; 338 339 /* This can be any valid CPU ID so we don't need locking. */ 340 cpu = raw_smp_processor_id(); 341 342 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 343 struct crypto_comp *tfm; 344 345 tfms = pos->tfms; 346 tfm = *per_cpu_ptr(tfms, cpu); 347 348 if (!strcmp(crypto_comp_name(tfm), alg_name)) { 349 pos->users++; 350 return tfms; 351 } 352 } 353 354 pos = kmalloc(sizeof(*pos), GFP_KERNEL); 355 if (!pos) 356 return NULL; 357 358 pos->users = 1; 359 INIT_LIST_HEAD(&pos->list); 360 list_add(&pos->list, &ipcomp6_tfms_list); 361 362 pos->tfms = tfms = alloc_percpu(struct crypto_comp *); 363 if (!tfms) 364 goto error; 365 366 for_each_possible_cpu(cpu) { 367 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0, 368 CRYPTO_ALG_ASYNC); 369 if (!tfm) 370 goto error; 371 *per_cpu_ptr(tfms, cpu) = tfm; 372 } 373 374 return tfms; 375 376 error: 377 ipcomp6_free_tfms(tfms); 378 return NULL; 379 } 380 381 static void ipcomp6_free_data(struct ipcomp_data *ipcd) 382 { 383 if (ipcd->tfms) 384 ipcomp6_free_tfms(ipcd->tfms); 385 ipcomp6_free_scratches(); 386 } 387 388 static void ipcomp6_destroy(struct xfrm_state *x) 389 { 390 struct ipcomp_data *ipcd = x->data; 391 if (!ipcd) 392 return; 393 xfrm_state_delete_tunnel(x); 394 mutex_lock(&ipcomp6_resource_mutex); 395 ipcomp6_free_data(ipcd); 396 mutex_unlock(&ipcomp6_resource_mutex); 397 kfree(ipcd); 398 399 xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr); 400 } 401 402 static int ipcomp6_init_state(struct xfrm_state *x) 403 { 404 int err; 405 struct ipcomp_data *ipcd; 406 struct xfrm_algo_desc *calg_desc; 407 408 err = -EINVAL; 409 if (!x->calg) 410 goto out; 411 412 if (x->encap) 413 goto out; 414 415 err = -ENOMEM; 416 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL); 417 if (!ipcd) 418 goto out; 419 420 x->props.header_len = 0; 421 if (x->props.mode == XFRM_MODE_TUNNEL) 422 x->props.header_len += sizeof(struct ipv6hdr); 423 424 mutex_lock(&ipcomp6_resource_mutex); 425 if (!ipcomp6_alloc_scratches()) 426 goto error; 427 428 ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name); 429 if (!ipcd->tfms) 430 goto error; 431 mutex_unlock(&ipcomp6_resource_mutex); 432 433 if (x->props.mode == XFRM_MODE_TUNNEL) { 434 err = ipcomp6_tunnel_attach(x); 435 if (err) 436 goto error_tunnel; 437 } 438 439 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0); 440 BUG_ON(!calg_desc); 441 ipcd->threshold = calg_desc->uinfo.comp.threshold; 442 x->data = ipcd; 443 err = 0; 444 out: 445 return err; 446 error_tunnel: 447 mutex_lock(&ipcomp6_resource_mutex); 448 error: 449 ipcomp6_free_data(ipcd); 450 mutex_unlock(&ipcomp6_resource_mutex); 451 kfree(ipcd); 452 453 goto out; 454 } 455 456 static struct xfrm_type ipcomp6_type = 457 { 458 .description = "IPCOMP6", 459 .owner = THIS_MODULE, 460 .proto = IPPROTO_COMP, 461 .init_state = ipcomp6_init_state, 462 .destructor = ipcomp6_destroy, 463 .input = ipcomp6_input, 464 .output = ipcomp6_output, 465 .hdr_offset = xfrm6_find_1stfragopt, 466 }; 467 468 static struct inet6_protocol ipcomp6_protocol = 469 { 470 .handler = xfrm6_rcv, 471 .err_handler = ipcomp6_err, 472 .flags = INET6_PROTO_NOPOLICY, 473 }; 474 475 static int __init ipcomp6_init(void) 476 { 477 if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) { 478 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n"); 479 return -EAGAIN; 480 } 481 if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) { 482 printk(KERN_INFO "ipcomp6 init: can't add protocol\n"); 483 xfrm_unregister_type(&ipcomp6_type, AF_INET6); 484 return -EAGAIN; 485 } 486 return 0; 487 } 488 489 static void __exit ipcomp6_fini(void) 490 { 491 if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) 492 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n"); 493 if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0) 494 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n"); 495 } 496 497 module_init(ipcomp6_init); 498 module_exit(ipcomp6_fini); 499 MODULE_LICENSE("GPL"); 500 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173"); 501 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>"); 502 503 504