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_tfm **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_tfm *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_put(skb, dlen - plen); 113 memcpy(skb->data, scratch, dlen); 114 err = ipch->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 ipv6hdr *top_iph; 126 int hdr_len; 127 struct ipv6_comp_hdr *ipch; 128 struct ipcomp_data *ipcd = x->data; 129 int plen, dlen; 130 u8 *start, *scratch; 131 struct crypto_tfm *tfm; 132 int cpu; 133 134 hdr_len = skb->h.raw - skb->data; 135 136 /* check whether datagram len is larger than threshold */ 137 if ((skb->len - hdr_len) < ipcd->threshold) { 138 goto out_ok; 139 } 140 141 if (skb_linearize_cow(skb)) 142 goto out_ok; 143 144 /* compression */ 145 plen = skb->len - hdr_len; 146 dlen = IPCOMP_SCRATCH_SIZE; 147 start = skb->h.raw; 148 149 cpu = get_cpu(); 150 scratch = *per_cpu_ptr(ipcomp6_scratches, cpu); 151 tfm = *per_cpu_ptr(ipcd->tfms, cpu); 152 153 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen); 154 if (err || (dlen + sizeof(struct ipv6_comp_hdr)) >= plen) { 155 put_cpu(); 156 goto out_ok; 157 } 158 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen); 159 put_cpu(); 160 pskb_trim(skb, hdr_len + dlen + sizeof(struct ip_comp_hdr)); 161 162 /* insert ipcomp header and replace datagram */ 163 top_iph = (struct ipv6hdr *)skb->data; 164 165 top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr)); 166 167 ipch = (struct ipv6_comp_hdr *)start; 168 ipch->nexthdr = *skb->nh.raw; 169 ipch->flags = 0; 170 ipch->cpi = htons((u16 )ntohl(x->id.spi)); 171 *skb->nh.raw = IPPROTO_COMP; 172 173 out_ok: 174 return 0; 175 } 176 177 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 178 int type, int code, int offset, __u32 info) 179 { 180 u32 spi; 181 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 182 struct ipv6_comp_hdr *ipcomph = (struct ipv6_comp_hdr*)(skb->data+offset); 183 struct xfrm_state *x; 184 185 if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG) 186 return; 187 188 spi = htonl(ntohs(ipcomph->cpi)); 189 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6); 190 if (!x) 191 return; 192 193 printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIP6_FMT "\n", 194 spi, NIP6(iph->daddr)); 195 xfrm_state_put(x); 196 } 197 198 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x) 199 { 200 struct xfrm_state *t = NULL; 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 t->props.mode = 1; 215 memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr)); 216 217 if (xfrm_init_state(t)) 218 goto error; 219 220 atomic_set(&t->tunnel_users, 1); 221 222 out: 223 return t; 224 225 error: 226 t->km.state = XFRM_STATE_DEAD; 227 xfrm_state_put(t); 228 t = NULL; 229 goto out; 230 } 231 232 static int ipcomp6_tunnel_attach(struct xfrm_state *x) 233 { 234 int err = 0; 235 struct xfrm_state *t = NULL; 236 u32 spi; 237 238 spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr); 239 if (spi) 240 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr, 241 spi, IPPROTO_IPV6, AF_INET6); 242 if (!t) { 243 t = ipcomp6_tunnel_create(x); 244 if (!t) { 245 err = -EINVAL; 246 goto out; 247 } 248 xfrm_state_insert(t); 249 xfrm_state_hold(t); 250 } 251 x->tunnel = t; 252 atomic_inc(&t->tunnel_users); 253 254 out: 255 return err; 256 } 257 258 static void ipcomp6_free_scratches(void) 259 { 260 int i; 261 void **scratches; 262 263 if (--ipcomp6_scratch_users) 264 return; 265 266 scratches = ipcomp6_scratches; 267 if (!scratches) 268 return; 269 270 for_each_possible_cpu(i) { 271 void *scratch = *per_cpu_ptr(scratches, i); 272 273 vfree(scratch); 274 } 275 276 free_percpu(scratches); 277 } 278 279 static void **ipcomp6_alloc_scratches(void) 280 { 281 int i; 282 void **scratches; 283 284 if (ipcomp6_scratch_users++) 285 return ipcomp6_scratches; 286 287 scratches = alloc_percpu(void *); 288 if (!scratches) 289 return NULL; 290 291 ipcomp6_scratches = scratches; 292 293 for_each_possible_cpu(i) { 294 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); 295 if (!scratch) 296 return NULL; 297 *per_cpu_ptr(scratches, i) = scratch; 298 } 299 300 return scratches; 301 } 302 303 static void ipcomp6_free_tfms(struct crypto_tfm **tfms) 304 { 305 struct ipcomp6_tfms *pos; 306 int cpu; 307 308 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 309 if (pos->tfms == tfms) 310 break; 311 } 312 313 BUG_TRAP(pos); 314 315 if (--pos->users) 316 return; 317 318 list_del(&pos->list); 319 kfree(pos); 320 321 if (!tfms) 322 return; 323 324 for_each_possible_cpu(cpu) { 325 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu); 326 crypto_free_tfm(tfm); 327 } 328 free_percpu(tfms); 329 } 330 331 static struct crypto_tfm **ipcomp6_alloc_tfms(const char *alg_name) 332 { 333 struct ipcomp6_tfms *pos; 334 struct crypto_tfm **tfms; 335 int cpu; 336 337 /* This can be any valid CPU ID so we don't need locking. */ 338 cpu = raw_smp_processor_id(); 339 340 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 341 struct crypto_tfm *tfm; 342 343 tfms = pos->tfms; 344 tfm = *per_cpu_ptr(tfms, cpu); 345 346 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) { 347 pos->users++; 348 return tfms; 349 } 350 } 351 352 pos = kmalloc(sizeof(*pos), GFP_KERNEL); 353 if (!pos) 354 return NULL; 355 356 pos->users = 1; 357 INIT_LIST_HEAD(&pos->list); 358 list_add(&pos->list, &ipcomp6_tfms_list); 359 360 pos->tfms = tfms = alloc_percpu(struct crypto_tfm *); 361 if (!tfms) 362 goto error; 363 364 for_each_possible_cpu(cpu) { 365 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0); 366 if (!tfm) 367 goto error; 368 *per_cpu_ptr(tfms, cpu) = tfm; 369 } 370 371 return tfms; 372 373 error: 374 ipcomp6_free_tfms(tfms); 375 return NULL; 376 } 377 378 static void ipcomp6_free_data(struct ipcomp_data *ipcd) 379 { 380 if (ipcd->tfms) 381 ipcomp6_free_tfms(ipcd->tfms); 382 ipcomp6_free_scratches(); 383 } 384 385 static void ipcomp6_destroy(struct xfrm_state *x) 386 { 387 struct ipcomp_data *ipcd = x->data; 388 if (!ipcd) 389 return; 390 xfrm_state_delete_tunnel(x); 391 mutex_lock(&ipcomp6_resource_mutex); 392 ipcomp6_free_data(ipcd); 393 mutex_unlock(&ipcomp6_resource_mutex); 394 kfree(ipcd); 395 396 xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr); 397 } 398 399 static int ipcomp6_init_state(struct xfrm_state *x) 400 { 401 int err; 402 struct ipcomp_data *ipcd; 403 struct xfrm_algo_desc *calg_desc; 404 405 err = -EINVAL; 406 if (!x->calg) 407 goto out; 408 409 if (x->encap) 410 goto out; 411 412 err = -ENOMEM; 413 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL); 414 if (!ipcd) 415 goto out; 416 417 x->props.header_len = 0; 418 if (x->props.mode) 419 x->props.header_len += sizeof(struct ipv6hdr); 420 421 mutex_lock(&ipcomp6_resource_mutex); 422 if (!ipcomp6_alloc_scratches()) 423 goto error; 424 425 ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name); 426 if (!ipcd->tfms) 427 goto error; 428 mutex_unlock(&ipcomp6_resource_mutex); 429 430 if (x->props.mode) { 431 err = ipcomp6_tunnel_attach(x); 432 if (err) 433 goto error_tunnel; 434 } 435 436 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0); 437 BUG_ON(!calg_desc); 438 ipcd->threshold = calg_desc->uinfo.comp.threshold; 439 x->data = ipcd; 440 err = 0; 441 out: 442 return err; 443 error_tunnel: 444 mutex_lock(&ipcomp6_resource_mutex); 445 error: 446 ipcomp6_free_data(ipcd); 447 mutex_unlock(&ipcomp6_resource_mutex); 448 kfree(ipcd); 449 450 goto out; 451 } 452 453 static struct xfrm_type ipcomp6_type = 454 { 455 .description = "IPCOMP6", 456 .owner = THIS_MODULE, 457 .proto = IPPROTO_COMP, 458 .init_state = ipcomp6_init_state, 459 .destructor = ipcomp6_destroy, 460 .input = ipcomp6_input, 461 .output = ipcomp6_output, 462 }; 463 464 static struct inet6_protocol ipcomp6_protocol = 465 { 466 .handler = xfrm6_rcv, 467 .err_handler = ipcomp6_err, 468 .flags = INET6_PROTO_NOPOLICY, 469 }; 470 471 static int __init ipcomp6_init(void) 472 { 473 if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) { 474 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n"); 475 return -EAGAIN; 476 } 477 if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) { 478 printk(KERN_INFO "ipcomp6 init: can't add protocol\n"); 479 xfrm_unregister_type(&ipcomp6_type, AF_INET6); 480 return -EAGAIN; 481 } 482 return 0; 483 } 484 485 static void __exit ipcomp6_fini(void) 486 { 487 if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) 488 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n"); 489 if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0) 490 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n"); 491 } 492 493 module_init(ipcomp6_init); 494 module_exit(ipcomp6_fini); 495 MODULE_LICENSE("GPL"); 496 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173"); 497 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>"); 498 499 500