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 = skb->nh.ipv6h; 83 ipch = (void *)skb->data; 84 skb->h.raw = skb->nh.raw + 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 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_comp *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, __be32 info) 180 { 181 __be32 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 u8 mode = XFRM_MODE_TUNNEL; 203 204 t = xfrm_state_alloc(); 205 if (!t) 206 goto out; 207 208 t->id.proto = IPPROTO_IPV6; 209 t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr); 210 if (!t->id.spi) 211 goto error; 212 213 memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr)); 214 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 215 t->props.family = AF_INET6; 216 if (x->props.mode == XFRM_MODE_BEET) 217 mode = x->props.mode; 218 t->props.mode = mode; 219 memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr)); 220 221 if (xfrm_init_state(t)) 222 goto error; 223 224 atomic_set(&t->tunnel_users, 1); 225 226 out: 227 return t; 228 229 error: 230 t->km.state = XFRM_STATE_DEAD; 231 xfrm_state_put(t); 232 t = NULL; 233 goto out; 234 } 235 236 static int ipcomp6_tunnel_attach(struct xfrm_state *x) 237 { 238 int err = 0; 239 struct xfrm_state *t = NULL; 240 __be32 spi; 241 242 spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr); 243 if (spi) 244 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr, 245 spi, IPPROTO_IPV6, AF_INET6); 246 if (!t) { 247 t = ipcomp6_tunnel_create(x); 248 if (!t) { 249 err = -EINVAL; 250 goto out; 251 } 252 xfrm_state_insert(t); 253 xfrm_state_hold(t); 254 } 255 x->tunnel = t; 256 atomic_inc(&t->tunnel_users); 257 258 out: 259 return err; 260 } 261 262 static void ipcomp6_free_scratches(void) 263 { 264 int i; 265 void **scratches; 266 267 if (--ipcomp6_scratch_users) 268 return; 269 270 scratches = ipcomp6_scratches; 271 if (!scratches) 272 return; 273 274 for_each_possible_cpu(i) { 275 void *scratch = *per_cpu_ptr(scratches, i); 276 277 vfree(scratch); 278 } 279 280 free_percpu(scratches); 281 } 282 283 static void **ipcomp6_alloc_scratches(void) 284 { 285 int i; 286 void **scratches; 287 288 if (ipcomp6_scratch_users++) 289 return ipcomp6_scratches; 290 291 scratches = alloc_percpu(void *); 292 if (!scratches) 293 return NULL; 294 295 ipcomp6_scratches = scratches; 296 297 for_each_possible_cpu(i) { 298 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); 299 if (!scratch) 300 return NULL; 301 *per_cpu_ptr(scratches, i) = scratch; 302 } 303 304 return scratches; 305 } 306 307 static void ipcomp6_free_tfms(struct crypto_comp **tfms) 308 { 309 struct ipcomp6_tfms *pos; 310 int cpu; 311 312 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 313 if (pos->tfms == tfms) 314 break; 315 } 316 317 BUG_TRAP(pos); 318 319 if (--pos->users) 320 return; 321 322 list_del(&pos->list); 323 kfree(pos); 324 325 if (!tfms) 326 return; 327 328 for_each_possible_cpu(cpu) { 329 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu); 330 crypto_free_comp(tfm); 331 } 332 free_percpu(tfms); 333 } 334 335 static struct crypto_comp **ipcomp6_alloc_tfms(const char *alg_name) 336 { 337 struct ipcomp6_tfms *pos; 338 struct crypto_comp **tfms; 339 int cpu; 340 341 /* This can be any valid CPU ID so we don't need locking. */ 342 cpu = raw_smp_processor_id(); 343 344 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 345 struct crypto_comp *tfm; 346 347 tfms = pos->tfms; 348 tfm = *per_cpu_ptr(tfms, cpu); 349 350 if (!strcmp(crypto_comp_name(tfm), alg_name)) { 351 pos->users++; 352 return tfms; 353 } 354 } 355 356 pos = kmalloc(sizeof(*pos), GFP_KERNEL); 357 if (!pos) 358 return NULL; 359 360 pos->users = 1; 361 INIT_LIST_HEAD(&pos->list); 362 list_add(&pos->list, &ipcomp6_tfms_list); 363 364 pos->tfms = tfms = alloc_percpu(struct crypto_comp *); 365 if (!tfms) 366 goto error; 367 368 for_each_possible_cpu(cpu) { 369 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0, 370 CRYPTO_ALG_ASYNC); 371 if (!tfm) 372 goto error; 373 *per_cpu_ptr(tfms, cpu) = tfm; 374 } 375 376 return tfms; 377 378 error: 379 ipcomp6_free_tfms(tfms); 380 return NULL; 381 } 382 383 static void ipcomp6_free_data(struct ipcomp_data *ipcd) 384 { 385 if (ipcd->tfms) 386 ipcomp6_free_tfms(ipcd->tfms); 387 ipcomp6_free_scratches(); 388 } 389 390 static void ipcomp6_destroy(struct xfrm_state *x) 391 { 392 struct ipcomp_data *ipcd = x->data; 393 if (!ipcd) 394 return; 395 xfrm_state_delete_tunnel(x); 396 mutex_lock(&ipcomp6_resource_mutex); 397 ipcomp6_free_data(ipcd); 398 mutex_unlock(&ipcomp6_resource_mutex); 399 kfree(ipcd); 400 401 xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr); 402 } 403 404 static int ipcomp6_init_state(struct xfrm_state *x) 405 { 406 int err; 407 struct ipcomp_data *ipcd; 408 struct xfrm_algo_desc *calg_desc; 409 410 err = -EINVAL; 411 if (!x->calg) 412 goto out; 413 414 if (x->encap) 415 goto out; 416 417 err = -ENOMEM; 418 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL); 419 if (!ipcd) 420 goto out; 421 422 x->props.header_len = 0; 423 if (x->props.mode == XFRM_MODE_TUNNEL) 424 x->props.header_len += sizeof(struct ipv6hdr); 425 426 mutex_lock(&ipcomp6_resource_mutex); 427 if (!ipcomp6_alloc_scratches()) 428 goto error; 429 430 ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name); 431 if (!ipcd->tfms) 432 goto error; 433 mutex_unlock(&ipcomp6_resource_mutex); 434 435 if (x->props.mode == XFRM_MODE_TUNNEL) { 436 err = ipcomp6_tunnel_attach(x); 437 if (err) 438 goto error_tunnel; 439 } 440 441 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0); 442 BUG_ON(!calg_desc); 443 ipcd->threshold = calg_desc->uinfo.comp.threshold; 444 x->data = ipcd; 445 err = 0; 446 out: 447 return err; 448 error_tunnel: 449 mutex_lock(&ipcomp6_resource_mutex); 450 error: 451 ipcomp6_free_data(ipcd); 452 mutex_unlock(&ipcomp6_resource_mutex); 453 kfree(ipcd); 454 455 goto out; 456 } 457 458 static struct xfrm_type ipcomp6_type = 459 { 460 .description = "IPCOMP6", 461 .owner = THIS_MODULE, 462 .proto = IPPROTO_COMP, 463 .init_state = ipcomp6_init_state, 464 .destructor = ipcomp6_destroy, 465 .input = ipcomp6_input, 466 .output = ipcomp6_output, 467 .hdr_offset = xfrm6_find_1stfragopt, 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>"); 504 505 506