1 /* 2 * IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173 3 * 4 * Copyright (C)2003 USAGI/WIDE Project 5 * 6 * Author Mitsuru KANDA <[email protected]> 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/semaphore.h> 38 #include <linux/crypto.h> 39 #include <linux/err.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 nexthdr; 68 int err = -ENOMEM; 69 struct ip_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 ipch = (void *)skb->data; 83 nexthdr = ipch->nexthdr; 84 85 skb->transport_header = skb->network_header + sizeof(*ipch); 86 __skb_pull(skb, sizeof(*ipch)); 87 88 /* decompression */ 89 plen = skb->len; 90 dlen = IPCOMP_SCRATCH_SIZE; 91 start = skb->data; 92 93 cpu = get_cpu(); 94 scratch = *per_cpu_ptr(ipcomp6_scratches, cpu); 95 tfm = *per_cpu_ptr(ipcd->tfms, cpu); 96 97 err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen); 98 if (err) 99 goto out_put_cpu; 100 101 if (dlen < (plen + sizeof(*ipch))) { 102 err = -EINVAL; 103 goto out_put_cpu; 104 } 105 106 err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC); 107 if (err) { 108 goto out_put_cpu; 109 } 110 111 skb->truesize += dlen - plen; 112 __skb_put(skb, dlen - plen); 113 skb_copy_to_linear_data(skb, scratch, dlen); 114 err = nexthdr; 115 116 out_put_cpu: 117 put_cpu(); 118 out: 119 return err; 120 } 121 122 static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb) 123 { 124 int err; 125 struct ip_comp_hdr *ipch; 126 struct ipcomp_data *ipcd = x->data; 127 int plen, dlen; 128 u8 *start, *scratch; 129 struct crypto_comp *tfm; 130 int cpu; 131 132 /* check whether datagram len is larger than threshold */ 133 if (skb->len < ipcd->threshold) { 134 goto out_ok; 135 } 136 137 if (skb_linearize_cow(skb)) 138 goto out_ok; 139 140 /* compression */ 141 plen = skb->len; 142 dlen = IPCOMP_SCRATCH_SIZE; 143 start = skb->data; 144 145 cpu = get_cpu(); 146 scratch = *per_cpu_ptr(ipcomp6_scratches, cpu); 147 tfm = *per_cpu_ptr(ipcd->tfms, cpu); 148 149 local_bh_disable(); 150 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen); 151 local_bh_enable(); 152 if (err || (dlen + sizeof(*ipch)) >= plen) { 153 put_cpu(); 154 goto out_ok; 155 } 156 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen); 157 put_cpu(); 158 pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr)); 159 160 /* insert ipcomp header and replace datagram */ 161 ipch = ip_comp_hdr(skb); 162 ipch->nexthdr = *skb_mac_header(skb); 163 ipch->flags = 0; 164 ipch->cpi = htons((u16 )ntohl(x->id.spi)); 165 *skb_mac_header(skb) = IPPROTO_COMP; 166 167 out_ok: 168 skb_push(skb, -skb_network_offset(skb)); 169 170 return 0; 171 } 172 173 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 174 int type, int code, int offset, __be32 info) 175 { 176 __be32 spi; 177 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 178 struct ip_comp_hdr *ipcomph = 179 (struct ip_comp_hdr *)(skb->data + offset); 180 struct xfrm_state *x; 181 182 if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG) 183 return; 184 185 spi = htonl(ntohs(ipcomph->cpi)); 186 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6); 187 if (!x) 188 return; 189 190 printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIP6_FMT "\n", 191 spi, NIP6(iph->daddr)); 192 xfrm_state_put(x); 193 } 194 195 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x) 196 { 197 struct xfrm_state *t = NULL; 198 199 t = xfrm_state_alloc(); 200 if (!t) 201 goto out; 202 203 t->id.proto = IPPROTO_IPV6; 204 t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr); 205 if (!t->id.spi) 206 goto error; 207 208 memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr)); 209 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 210 t->props.family = AF_INET6; 211 t->props.mode = x->props.mode; 212 memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr)); 213 214 if (xfrm_init_state(t)) 215 goto error; 216 217 atomic_set(&t->tunnel_users, 1); 218 219 out: 220 return t; 221 222 error: 223 t->km.state = XFRM_STATE_DEAD; 224 xfrm_state_put(t); 225 t = NULL; 226 goto out; 227 } 228 229 static int ipcomp6_tunnel_attach(struct xfrm_state *x) 230 { 231 int err = 0; 232 struct xfrm_state *t = NULL; 233 __be32 spi; 234 235 spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr); 236 if (spi) 237 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr, 238 spi, IPPROTO_IPV6, AF_INET6); 239 if (!t) { 240 t = ipcomp6_tunnel_create(x); 241 if (!t) { 242 err = -EINVAL; 243 goto out; 244 } 245 xfrm_state_insert(t); 246 xfrm_state_hold(t); 247 } 248 x->tunnel = t; 249 atomic_inc(&t->tunnel_users); 250 251 out: 252 return err; 253 } 254 255 static void ipcomp6_free_scratches(void) 256 { 257 int i; 258 void **scratches; 259 260 if (--ipcomp6_scratch_users) 261 return; 262 263 scratches = ipcomp6_scratches; 264 if (!scratches) 265 return; 266 267 for_each_possible_cpu(i) { 268 void *scratch = *per_cpu_ptr(scratches, i); 269 270 vfree(scratch); 271 } 272 273 free_percpu(scratches); 274 } 275 276 static void **ipcomp6_alloc_scratches(void) 277 { 278 int i; 279 void **scratches; 280 281 if (ipcomp6_scratch_users++) 282 return ipcomp6_scratches; 283 284 scratches = alloc_percpu(void *); 285 if (!scratches) 286 return NULL; 287 288 ipcomp6_scratches = scratches; 289 290 for_each_possible_cpu(i) { 291 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); 292 if (!scratch) 293 return NULL; 294 *per_cpu_ptr(scratches, i) = scratch; 295 } 296 297 return scratches; 298 } 299 300 static void ipcomp6_free_tfms(struct crypto_comp **tfms) 301 { 302 struct ipcomp6_tfms *pos; 303 int cpu; 304 305 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 306 if (pos->tfms == tfms) 307 break; 308 } 309 310 BUG_TRAP(pos); 311 312 if (--pos->users) 313 return; 314 315 list_del(&pos->list); 316 kfree(pos); 317 318 if (!tfms) 319 return; 320 321 for_each_possible_cpu(cpu) { 322 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu); 323 crypto_free_comp(tfm); 324 } 325 free_percpu(tfms); 326 } 327 328 static struct crypto_comp **ipcomp6_alloc_tfms(const char *alg_name) 329 { 330 struct ipcomp6_tfms *pos; 331 struct crypto_comp **tfms; 332 int cpu; 333 334 /* This can be any valid CPU ID so we don't need locking. */ 335 cpu = raw_smp_processor_id(); 336 337 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 338 struct crypto_comp *tfm; 339 340 tfms = pos->tfms; 341 tfm = *per_cpu_ptr(tfms, cpu); 342 343 if (!strcmp(crypto_comp_name(tfm), alg_name)) { 344 pos->users++; 345 return tfms; 346 } 347 } 348 349 pos = kmalloc(sizeof(*pos), GFP_KERNEL); 350 if (!pos) 351 return NULL; 352 353 pos->users = 1; 354 INIT_LIST_HEAD(&pos->list); 355 list_add(&pos->list, &ipcomp6_tfms_list); 356 357 pos->tfms = tfms = alloc_percpu(struct crypto_comp *); 358 if (!tfms) 359 goto error; 360 361 for_each_possible_cpu(cpu) { 362 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0, 363 CRYPTO_ALG_ASYNC); 364 if (IS_ERR(tfm)) 365 goto error; 366 *per_cpu_ptr(tfms, cpu) = tfm; 367 } 368 369 return tfms; 370 371 error: 372 ipcomp6_free_tfms(tfms); 373 return NULL; 374 } 375 376 static void ipcomp6_free_data(struct ipcomp_data *ipcd) 377 { 378 if (ipcd->tfms) 379 ipcomp6_free_tfms(ipcd->tfms); 380 ipcomp6_free_scratches(); 381 } 382 383 static void ipcomp6_destroy(struct xfrm_state *x) 384 { 385 struct ipcomp_data *ipcd = x->data; 386 if (!ipcd) 387 return; 388 xfrm_state_delete_tunnel(x); 389 mutex_lock(&ipcomp6_resource_mutex); 390 ipcomp6_free_data(ipcd); 391 mutex_unlock(&ipcomp6_resource_mutex); 392 kfree(ipcd); 393 394 xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr); 395 } 396 397 static int ipcomp6_init_state(struct xfrm_state *x) 398 { 399 int err; 400 struct ipcomp_data *ipcd; 401 struct xfrm_algo_desc *calg_desc; 402 403 err = -EINVAL; 404 if (!x->calg) 405 goto out; 406 407 if (x->encap) 408 goto out; 409 410 x->props.header_len = 0; 411 switch (x->props.mode) { 412 case XFRM_MODE_TRANSPORT: 413 break; 414 case XFRM_MODE_TUNNEL: 415 x->props.header_len += sizeof(struct ipv6hdr); 416 break; 417 default: 418 goto out; 419 } 420 421 err = -ENOMEM; 422 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL); 423 if (!ipcd) 424 goto out; 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 const 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 <[email protected]>"); 504 505 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP); 506