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/config.h> 34 #include <linux/module.h> 35 #include <net/ip.h> 36 #include <net/xfrm.h> 37 #include <net/ipcomp.h> 38 #include <asm/scatterlist.h> 39 #include <asm/semaphore.h> 40 #include <linux/crypto.h> 41 #include <linux/pfkeyv2.h> 42 #include <linux/random.h> 43 #include <linux/percpu.h> 44 #include <linux/smp.h> 45 #include <linux/list.h> 46 #include <linux/vmalloc.h> 47 #include <linux/rtnetlink.h> 48 #include <net/icmp.h> 49 #include <net/ipv6.h> 50 #include <net/protocol.h> 51 #include <linux/ipv6.h> 52 #include <linux/icmpv6.h> 53 #include <linux/mutex.h> 54 55 struct ipcomp6_tfms { 56 struct list_head list; 57 struct crypto_tfm **tfms; 58 int users; 59 }; 60 61 static DEFINE_MUTEX(ipcomp6_resource_mutex); 62 static void **ipcomp6_scratches; 63 static int ipcomp6_scratch_users; 64 static LIST_HEAD(ipcomp6_tfms_list); 65 66 static int ipcomp6_input(struct xfrm_state *x, struct sk_buff *skb) 67 { 68 int err = -ENOMEM; 69 struct ipv6hdr *iph; 70 struct ipv6_comp_hdr *ipch; 71 int plen, dlen; 72 struct ipcomp_data *ipcd = x->data; 73 u8 *start, *scratch; 74 struct crypto_tfm *tfm; 75 int cpu; 76 77 if (skb_linearize_cow(skb)) 78 goto out; 79 80 skb->ip_summed = CHECKSUM_NONE; 81 82 /* Remove ipcomp header and decompress original payload */ 83 iph = skb->nh.ipv6h; 84 ipch = (void *)skb->data; 85 skb->h.raw = skb->nh.raw + 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 err = -EINVAL; 100 goto out_put_cpu; 101 } 102 103 if (dlen < (plen + sizeof(struct ipv6_comp_hdr))) { 104 err = -EINVAL; 105 goto out_put_cpu; 106 } 107 108 err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC); 109 if (err) { 110 goto out_put_cpu; 111 } 112 113 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_tfm *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, __u32 info) 180 { 181 u32 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; 202 203 t = xfrm_state_alloc(); 204 if (!t) 205 goto out; 206 207 t->id.proto = IPPROTO_IPV6; 208 t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr); 209 if (!t->id.spi) 210 goto error; 211 212 memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr)); 213 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 214 t->props.family = AF_INET6; 215 t->props.mode = 1; 216 memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr)); 217 218 if (xfrm_init_state(t)) 219 goto error; 220 221 atomic_set(&t->tunnel_users, 1); 222 223 out: 224 return t; 225 226 error: 227 t->km.state = XFRM_STATE_DEAD; 228 xfrm_state_put(t); 229 t = NULL; 230 goto out; 231 } 232 233 static int ipcomp6_tunnel_attach(struct xfrm_state *x) 234 { 235 int err = 0; 236 struct xfrm_state *t = NULL; 237 u32 spi; 238 239 spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr); 240 if (spi) 241 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr, 242 spi, IPPROTO_IPV6, AF_INET6); 243 if (!t) { 244 t = ipcomp6_tunnel_create(x); 245 if (!t) { 246 err = -EINVAL; 247 goto out; 248 } 249 xfrm_state_insert(t); 250 xfrm_state_hold(t); 251 } 252 x->tunnel = t; 253 atomic_inc(&t->tunnel_users); 254 255 out: 256 return err; 257 } 258 259 static void ipcomp6_free_scratches(void) 260 { 261 int i; 262 void **scratches; 263 264 if (--ipcomp6_scratch_users) 265 return; 266 267 scratches = ipcomp6_scratches; 268 if (!scratches) 269 return; 270 271 for_each_possible_cpu(i) { 272 void *scratch = *per_cpu_ptr(scratches, i); 273 274 vfree(scratch); 275 } 276 277 free_percpu(scratches); 278 } 279 280 static void **ipcomp6_alloc_scratches(void) 281 { 282 int i; 283 void **scratches; 284 285 if (ipcomp6_scratch_users++) 286 return ipcomp6_scratches; 287 288 scratches = alloc_percpu(void *); 289 if (!scratches) 290 return NULL; 291 292 ipcomp6_scratches = scratches; 293 294 for_each_possible_cpu(i) { 295 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); 296 if (!scratch) 297 return NULL; 298 *per_cpu_ptr(scratches, i) = scratch; 299 } 300 301 return scratches; 302 } 303 304 static void ipcomp6_free_tfms(struct crypto_tfm **tfms) 305 { 306 struct ipcomp6_tfms *pos; 307 int cpu; 308 309 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 310 if (pos->tfms == tfms) 311 break; 312 } 313 314 BUG_TRAP(pos); 315 316 if (--pos->users) 317 return; 318 319 list_del(&pos->list); 320 kfree(pos); 321 322 if (!tfms) 323 return; 324 325 for_each_possible_cpu(cpu) { 326 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu); 327 crypto_free_tfm(tfm); 328 } 329 free_percpu(tfms); 330 } 331 332 static struct crypto_tfm **ipcomp6_alloc_tfms(const char *alg_name) 333 { 334 struct ipcomp6_tfms *pos; 335 struct crypto_tfm **tfms; 336 int cpu; 337 338 /* This can be any valid CPU ID so we don't need locking. */ 339 cpu = raw_smp_processor_id(); 340 341 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 342 struct crypto_tfm *tfm; 343 344 tfms = pos->tfms; 345 tfm = *per_cpu_ptr(tfms, cpu); 346 347 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) { 348 pos->users++; 349 return tfms; 350 } 351 } 352 353 pos = kmalloc(sizeof(*pos), GFP_KERNEL); 354 if (!pos) 355 return NULL; 356 357 pos->users = 1; 358 INIT_LIST_HEAD(&pos->list); 359 list_add(&pos->list, &ipcomp6_tfms_list); 360 361 pos->tfms = tfms = alloc_percpu(struct crypto_tfm *); 362 if (!tfms) 363 goto error; 364 365 for_each_possible_cpu(cpu) { 366 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0); 367 if (!tfm) 368 goto error; 369 *per_cpu_ptr(tfms, cpu) = tfm; 370 } 371 372 return tfms; 373 374 error: 375 ipcomp6_free_tfms(tfms); 376 return NULL; 377 } 378 379 static void ipcomp6_free_data(struct ipcomp_data *ipcd) 380 { 381 if (ipcd->tfms) 382 ipcomp6_free_tfms(ipcd->tfms); 383 ipcomp6_free_scratches(); 384 } 385 386 static void ipcomp6_destroy(struct xfrm_state *x) 387 { 388 struct ipcomp_data *ipcd = x->data; 389 if (!ipcd) 390 return; 391 xfrm_state_delete_tunnel(x); 392 mutex_lock(&ipcomp6_resource_mutex); 393 ipcomp6_free_data(ipcd); 394 mutex_unlock(&ipcomp6_resource_mutex); 395 kfree(ipcd); 396 397 xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr); 398 } 399 400 static int ipcomp6_init_state(struct xfrm_state *x) 401 { 402 int err; 403 struct ipcomp_data *ipcd; 404 struct xfrm_algo_desc *calg_desc; 405 406 err = -EINVAL; 407 if (!x->calg) 408 goto out; 409 410 if (x->encap) 411 goto out; 412 413 err = -ENOMEM; 414 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL); 415 if (!ipcd) 416 goto out; 417 418 x->props.header_len = 0; 419 if (x->props.mode) 420 x->props.header_len += sizeof(struct ipv6hdr); 421 422 mutex_lock(&ipcomp6_resource_mutex); 423 if (!ipcomp6_alloc_scratches()) 424 goto error; 425 426 ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name); 427 if (!ipcd->tfms) 428 goto error; 429 mutex_unlock(&ipcomp6_resource_mutex); 430 431 if (x->props.mode) { 432 err = ipcomp6_tunnel_attach(x); 433 if (err) 434 goto error_tunnel; 435 } 436 437 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0); 438 BUG_ON(!calg_desc); 439 ipcd->threshold = calg_desc->uinfo.comp.threshold; 440 x->data = ipcd; 441 err = 0; 442 out: 443 return err; 444 error_tunnel: 445 mutex_lock(&ipcomp6_resource_mutex); 446 error: 447 ipcomp6_free_data(ipcd); 448 mutex_unlock(&ipcomp6_resource_mutex); 449 kfree(ipcd); 450 451 goto out; 452 } 453 454 static struct xfrm_type ipcomp6_type = 455 { 456 .description = "IPCOMP6", 457 .owner = THIS_MODULE, 458 .proto = IPPROTO_COMP, 459 .init_state = ipcomp6_init_state, 460 .destructor = ipcomp6_destroy, 461 .input = ipcomp6_input, 462 .output = ipcomp6_output, 463 }; 464 465 static struct inet6_protocol ipcomp6_protocol = 466 { 467 .handler = xfrm6_rcv, 468 .err_handler = ipcomp6_err, 469 .flags = INET6_PROTO_NOPOLICY, 470 }; 471 472 static int __init ipcomp6_init(void) 473 { 474 if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) { 475 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n"); 476 return -EAGAIN; 477 } 478 if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) { 479 printk(KERN_INFO "ipcomp6 init: can't add protocol\n"); 480 xfrm_unregister_type(&ipcomp6_type, AF_INET6); 481 return -EAGAIN; 482 } 483 return 0; 484 } 485 486 static void __exit ipcomp6_fini(void) 487 { 488 if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) 489 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n"); 490 if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0) 491 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n"); 492 } 493 494 module_init(ipcomp6_init); 495 module_exit(ipcomp6_fini); 496 MODULE_LICENSE("GPL"); 497 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173"); 498 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>"); 499 500 501