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 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 skb->transport_header = skb->network_header + sizeof(*ipch); 83 __skb_pull(skb, sizeof(*ipch)); 84 85 /* decompression */ 86 plen = skb->len; 87 dlen = IPCOMP_SCRATCH_SIZE; 88 start = skb->data; 89 90 cpu = get_cpu(); 91 scratch = *per_cpu_ptr(ipcomp6_scratches, cpu); 92 tfm = *per_cpu_ptr(ipcd->tfms, cpu); 93 94 err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen); 95 if (err) 96 goto out_put_cpu; 97 98 if (dlen < (plen + sizeof(*ipch))) { 99 err = -EINVAL; 100 goto out_put_cpu; 101 } 102 103 err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC); 104 if (err) { 105 goto out_put_cpu; 106 } 107 108 skb->truesize += dlen - plen; 109 __skb_put(skb, dlen - plen); 110 skb_copy_to_linear_data(skb, scratch, dlen); 111 err = ipch->nexthdr; 112 113 out_put_cpu: 114 put_cpu(); 115 out: 116 return err; 117 } 118 119 static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb) 120 { 121 int err; 122 struct ip_comp_hdr *ipch; 123 struct ipcomp_data *ipcd = x->data; 124 int plen, dlen; 125 u8 *start, *scratch; 126 struct crypto_comp *tfm; 127 int cpu; 128 129 /* check whether datagram len is larger than threshold */ 130 if (skb->len < ipcd->threshold) { 131 goto out_ok; 132 } 133 134 if (skb_linearize_cow(skb)) 135 goto out_ok; 136 137 /* compression */ 138 plen = skb->len; 139 dlen = IPCOMP_SCRATCH_SIZE; 140 start = skb->data; 141 142 cpu = get_cpu(); 143 scratch = *per_cpu_ptr(ipcomp6_scratches, cpu); 144 tfm = *per_cpu_ptr(ipcd->tfms, cpu); 145 146 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen); 147 if (err || (dlen + sizeof(*ipch)) >= plen) { 148 put_cpu(); 149 goto out_ok; 150 } 151 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen); 152 put_cpu(); 153 pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr)); 154 155 /* insert ipcomp header and replace datagram */ 156 ipch = ip_comp_hdr(skb); 157 ipch->nexthdr = *skb_mac_header(skb); 158 ipch->flags = 0; 159 ipch->cpi = htons((u16 )ntohl(x->id.spi)); 160 *skb_mac_header(skb) = IPPROTO_COMP; 161 162 out_ok: 163 skb_push(skb, -skb_network_offset(skb)); 164 165 return 0; 166 } 167 168 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 169 int type, int code, int offset, __be32 info) 170 { 171 __be32 spi; 172 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 173 struct ip_comp_hdr *ipcomph = 174 (struct ip_comp_hdr *)(skb->data + offset); 175 struct xfrm_state *x; 176 177 if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG) 178 return; 179 180 spi = htonl(ntohs(ipcomph->cpi)); 181 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6); 182 if (!x) 183 return; 184 185 printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIP6_FMT "\n", 186 spi, NIP6(iph->daddr)); 187 xfrm_state_put(x); 188 } 189 190 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x) 191 { 192 struct xfrm_state *t = NULL; 193 u8 mode = XFRM_MODE_TUNNEL; 194 195 t = xfrm_state_alloc(); 196 if (!t) 197 goto out; 198 199 t->id.proto = IPPROTO_IPV6; 200 t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr); 201 if (!t->id.spi) 202 goto error; 203 204 memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr)); 205 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 206 t->props.family = AF_INET6; 207 if (x->props.mode == XFRM_MODE_BEET) 208 mode = x->props.mode; 209 t->props.mode = mode; 210 memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr)); 211 212 if (xfrm_init_state(t)) 213 goto error; 214 215 atomic_set(&t->tunnel_users, 1); 216 217 out: 218 return t; 219 220 error: 221 t->km.state = XFRM_STATE_DEAD; 222 xfrm_state_put(t); 223 t = NULL; 224 goto out; 225 } 226 227 static int ipcomp6_tunnel_attach(struct xfrm_state *x) 228 { 229 int err = 0; 230 struct xfrm_state *t = NULL; 231 __be32 spi; 232 233 spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr); 234 if (spi) 235 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr, 236 spi, IPPROTO_IPV6, AF_INET6); 237 if (!t) { 238 t = ipcomp6_tunnel_create(x); 239 if (!t) { 240 err = -EINVAL; 241 goto out; 242 } 243 xfrm_state_insert(t); 244 xfrm_state_hold(t); 245 } 246 x->tunnel = t; 247 atomic_inc(&t->tunnel_users); 248 249 out: 250 return err; 251 } 252 253 static void ipcomp6_free_scratches(void) 254 { 255 int i; 256 void **scratches; 257 258 if (--ipcomp6_scratch_users) 259 return; 260 261 scratches = ipcomp6_scratches; 262 if (!scratches) 263 return; 264 265 for_each_possible_cpu(i) { 266 void *scratch = *per_cpu_ptr(scratches, i); 267 268 vfree(scratch); 269 } 270 271 free_percpu(scratches); 272 } 273 274 static void **ipcomp6_alloc_scratches(void) 275 { 276 int i; 277 void **scratches; 278 279 if (ipcomp6_scratch_users++) 280 return ipcomp6_scratches; 281 282 scratches = alloc_percpu(void *); 283 if (!scratches) 284 return NULL; 285 286 ipcomp6_scratches = scratches; 287 288 for_each_possible_cpu(i) { 289 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); 290 if (!scratch) 291 return NULL; 292 *per_cpu_ptr(scratches, i) = scratch; 293 } 294 295 return scratches; 296 } 297 298 static void ipcomp6_free_tfms(struct crypto_comp **tfms) 299 { 300 struct ipcomp6_tfms *pos; 301 int cpu; 302 303 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 304 if (pos->tfms == tfms) 305 break; 306 } 307 308 BUG_TRAP(pos); 309 310 if (--pos->users) 311 return; 312 313 list_del(&pos->list); 314 kfree(pos); 315 316 if (!tfms) 317 return; 318 319 for_each_possible_cpu(cpu) { 320 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu); 321 crypto_free_comp(tfm); 322 } 323 free_percpu(tfms); 324 } 325 326 static struct crypto_comp **ipcomp6_alloc_tfms(const char *alg_name) 327 { 328 struct ipcomp6_tfms *pos; 329 struct crypto_comp **tfms; 330 int cpu; 331 332 /* This can be any valid CPU ID so we don't need locking. */ 333 cpu = raw_smp_processor_id(); 334 335 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 336 struct crypto_comp *tfm; 337 338 tfms = pos->tfms; 339 tfm = *per_cpu_ptr(tfms, cpu); 340 341 if (!strcmp(crypto_comp_name(tfm), alg_name)) { 342 pos->users++; 343 return tfms; 344 } 345 } 346 347 pos = kmalloc(sizeof(*pos), GFP_KERNEL); 348 if (!pos) 349 return NULL; 350 351 pos->users = 1; 352 INIT_LIST_HEAD(&pos->list); 353 list_add(&pos->list, &ipcomp6_tfms_list); 354 355 pos->tfms = tfms = alloc_percpu(struct crypto_comp *); 356 if (!tfms) 357 goto error; 358 359 for_each_possible_cpu(cpu) { 360 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0, 361 CRYPTO_ALG_ASYNC); 362 if (!tfm) 363 goto error; 364 *per_cpu_ptr(tfms, cpu) = tfm; 365 } 366 367 return tfms; 368 369 error: 370 ipcomp6_free_tfms(tfms); 371 return NULL; 372 } 373 374 static void ipcomp6_free_data(struct ipcomp_data *ipcd) 375 { 376 if (ipcd->tfms) 377 ipcomp6_free_tfms(ipcd->tfms); 378 ipcomp6_free_scratches(); 379 } 380 381 static void ipcomp6_destroy(struct xfrm_state *x) 382 { 383 struct ipcomp_data *ipcd = x->data; 384 if (!ipcd) 385 return; 386 xfrm_state_delete_tunnel(x); 387 mutex_lock(&ipcomp6_resource_mutex); 388 ipcomp6_free_data(ipcd); 389 mutex_unlock(&ipcomp6_resource_mutex); 390 kfree(ipcd); 391 392 xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr); 393 } 394 395 static int ipcomp6_init_state(struct xfrm_state *x) 396 { 397 int err; 398 struct ipcomp_data *ipcd; 399 struct xfrm_algo_desc *calg_desc; 400 401 err = -EINVAL; 402 if (!x->calg) 403 goto out; 404 405 if (x->encap) 406 goto out; 407 408 err = -ENOMEM; 409 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL); 410 if (!ipcd) 411 goto out; 412 413 x->props.header_len = 0; 414 switch (x->props.mode) { 415 case XFRM_MODE_BEET: 416 case XFRM_MODE_TRANSPORT: 417 break; 418 case XFRM_MODE_TUNNEL: 419 x->props.header_len += sizeof(struct ipv6hdr); 420 default: 421 goto error; 422 } 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 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP); 504