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 = 0; 69 u8 nexthdr = 0; 70 int hdr_len = skb->h.raw - skb->nh.raw; 71 unsigned char *tmp_hdr = NULL; 72 struct ipv6hdr *iph; 73 int plen, dlen; 74 struct ipcomp_data *ipcd = x->data; 75 u8 *start, *scratch; 76 struct crypto_tfm *tfm; 77 int cpu; 78 79 if ((skb_is_nonlinear(skb) || skb_cloned(skb)) && 80 skb_linearize(skb, GFP_ATOMIC) != 0) { 81 err = -ENOMEM; 82 goto out; 83 } 84 85 skb->ip_summed = CHECKSUM_NONE; 86 87 /* Remove ipcomp header and decompress original payload */ 88 iph = skb->nh.ipv6h; 89 tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC); 90 if (!tmp_hdr) 91 goto out; 92 memcpy(tmp_hdr, iph, hdr_len); 93 nexthdr = *(u8 *)skb->data; 94 skb_pull(skb, sizeof(struct ipv6_comp_hdr)); 95 skb->nh.raw += sizeof(struct ipv6_comp_hdr); 96 memcpy(skb->nh.raw, tmp_hdr, hdr_len); 97 iph = skb->nh.ipv6h; 98 iph->payload_len = htons(ntohs(iph->payload_len) - sizeof(struct ipv6_comp_hdr)); 99 skb->h.raw = skb->data; 100 101 /* decompression */ 102 plen = skb->len; 103 dlen = IPCOMP_SCRATCH_SIZE; 104 start = skb->data; 105 106 cpu = get_cpu(); 107 scratch = *per_cpu_ptr(ipcomp6_scratches, cpu); 108 tfm = *per_cpu_ptr(ipcd->tfms, cpu); 109 110 err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen); 111 if (err) { 112 err = -EINVAL; 113 goto out_put_cpu; 114 } 115 116 if (dlen < (plen + sizeof(struct ipv6_comp_hdr))) { 117 err = -EINVAL; 118 goto out_put_cpu; 119 } 120 121 err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC); 122 if (err) { 123 goto out_put_cpu; 124 } 125 126 skb_put(skb, dlen - plen); 127 memcpy(skb->data, scratch, dlen); 128 129 iph = skb->nh.ipv6h; 130 iph->payload_len = htons(skb->len); 131 132 out_put_cpu: 133 put_cpu(); 134 out: 135 kfree(tmp_hdr); 136 if (err) 137 goto error_out; 138 return nexthdr; 139 error_out: 140 return err; 141 } 142 143 static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb) 144 { 145 int err; 146 struct ipv6hdr *top_iph; 147 int hdr_len; 148 struct ipv6_comp_hdr *ipch; 149 struct ipcomp_data *ipcd = x->data; 150 int plen, dlen; 151 u8 *start, *scratch; 152 struct crypto_tfm *tfm; 153 int cpu; 154 155 hdr_len = skb->h.raw - skb->data; 156 157 /* check whether datagram len is larger than threshold */ 158 if ((skb->len - hdr_len) < ipcd->threshold) { 159 goto out_ok; 160 } 161 162 if ((skb_is_nonlinear(skb) || skb_cloned(skb)) && 163 skb_linearize(skb, GFP_ATOMIC) != 0) { 164 goto out_ok; 165 } 166 167 /* compression */ 168 plen = skb->len - hdr_len; 169 dlen = IPCOMP_SCRATCH_SIZE; 170 start = skb->h.raw; 171 172 cpu = get_cpu(); 173 scratch = *per_cpu_ptr(ipcomp6_scratches, cpu); 174 tfm = *per_cpu_ptr(ipcd->tfms, cpu); 175 176 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen); 177 if (err || (dlen + sizeof(struct ipv6_comp_hdr)) >= plen) { 178 put_cpu(); 179 goto out_ok; 180 } 181 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen); 182 put_cpu(); 183 pskb_trim(skb, hdr_len + dlen + sizeof(struct ip_comp_hdr)); 184 185 /* insert ipcomp header and replace datagram */ 186 top_iph = (struct ipv6hdr *)skb->data; 187 188 top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr)); 189 190 ipch = (struct ipv6_comp_hdr *)start; 191 ipch->nexthdr = *skb->nh.raw; 192 ipch->flags = 0; 193 ipch->cpi = htons((u16 )ntohl(x->id.spi)); 194 *skb->nh.raw = IPPROTO_COMP; 195 196 out_ok: 197 return 0; 198 } 199 200 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 201 int type, int code, int offset, __u32 info) 202 { 203 u32 spi; 204 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 205 struct ipv6_comp_hdr *ipcomph = (struct ipv6_comp_hdr*)(skb->data+offset); 206 struct xfrm_state *x; 207 208 if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG) 209 return; 210 211 spi = ntohl(ntohs(ipcomph->cpi)); 212 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6); 213 if (!x) 214 return; 215 216 printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIP6_FMT "\n", 217 spi, NIP6(iph->daddr)); 218 xfrm_state_put(x); 219 } 220 221 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x) 222 { 223 struct xfrm_state *t = NULL; 224 225 t = xfrm_state_alloc(); 226 if (!t) 227 goto out; 228 229 t->id.proto = IPPROTO_IPV6; 230 t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr); 231 if (!t->id.spi) 232 goto error; 233 234 memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr)); 235 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 236 t->props.family = AF_INET6; 237 t->props.mode = 1; 238 memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr)); 239 240 if (xfrm_init_state(t)) 241 goto error; 242 243 atomic_set(&t->tunnel_users, 1); 244 245 out: 246 return t; 247 248 error: 249 t->km.state = XFRM_STATE_DEAD; 250 xfrm_state_put(t); 251 t = NULL; 252 goto out; 253 } 254 255 static int ipcomp6_tunnel_attach(struct xfrm_state *x) 256 { 257 int err = 0; 258 struct xfrm_state *t = NULL; 259 u32 spi; 260 261 spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr); 262 if (spi) 263 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr, 264 spi, IPPROTO_IPV6, AF_INET6); 265 if (!t) { 266 t = ipcomp6_tunnel_create(x); 267 if (!t) { 268 err = -EINVAL; 269 goto out; 270 } 271 xfrm_state_insert(t); 272 xfrm_state_hold(t); 273 } 274 x->tunnel = t; 275 atomic_inc(&t->tunnel_users); 276 277 out: 278 return err; 279 } 280 281 static void ipcomp6_free_scratches(void) 282 { 283 int i; 284 void **scratches; 285 286 if (--ipcomp6_scratch_users) 287 return; 288 289 scratches = ipcomp6_scratches; 290 if (!scratches) 291 return; 292 293 for_each_possible_cpu(i) { 294 void *scratch = *per_cpu_ptr(scratches, i); 295 296 vfree(scratch); 297 } 298 299 free_percpu(scratches); 300 } 301 302 static void **ipcomp6_alloc_scratches(void) 303 { 304 int i; 305 void **scratches; 306 307 if (ipcomp6_scratch_users++) 308 return ipcomp6_scratches; 309 310 scratches = alloc_percpu(void *); 311 if (!scratches) 312 return NULL; 313 314 ipcomp6_scratches = scratches; 315 316 for_each_possible_cpu(i) { 317 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); 318 if (!scratch) 319 return NULL; 320 *per_cpu_ptr(scratches, i) = scratch; 321 } 322 323 return scratches; 324 } 325 326 static void ipcomp6_free_tfms(struct crypto_tfm **tfms) 327 { 328 struct ipcomp6_tfms *pos; 329 int cpu; 330 331 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 332 if (pos->tfms == tfms) 333 break; 334 } 335 336 BUG_TRAP(pos); 337 338 if (--pos->users) 339 return; 340 341 list_del(&pos->list); 342 kfree(pos); 343 344 if (!tfms) 345 return; 346 347 for_each_possible_cpu(cpu) { 348 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu); 349 crypto_free_tfm(tfm); 350 } 351 free_percpu(tfms); 352 } 353 354 static struct crypto_tfm **ipcomp6_alloc_tfms(const char *alg_name) 355 { 356 struct ipcomp6_tfms *pos; 357 struct crypto_tfm **tfms; 358 int cpu; 359 360 /* This can be any valid CPU ID so we don't need locking. */ 361 cpu = raw_smp_processor_id(); 362 363 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 364 struct crypto_tfm *tfm; 365 366 tfms = pos->tfms; 367 tfm = *per_cpu_ptr(tfms, cpu); 368 369 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) { 370 pos->users++; 371 return tfms; 372 } 373 } 374 375 pos = kmalloc(sizeof(*pos), GFP_KERNEL); 376 if (!pos) 377 return NULL; 378 379 pos->users = 1; 380 INIT_LIST_HEAD(&pos->list); 381 list_add(&pos->list, &ipcomp6_tfms_list); 382 383 pos->tfms = tfms = alloc_percpu(struct crypto_tfm *); 384 if (!tfms) 385 goto error; 386 387 for_each_possible_cpu(cpu) { 388 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0); 389 if (!tfm) 390 goto error; 391 *per_cpu_ptr(tfms, cpu) = tfm; 392 } 393 394 return tfms; 395 396 error: 397 ipcomp6_free_tfms(tfms); 398 return NULL; 399 } 400 401 static void ipcomp6_free_data(struct ipcomp_data *ipcd) 402 { 403 if (ipcd->tfms) 404 ipcomp6_free_tfms(ipcd->tfms); 405 ipcomp6_free_scratches(); 406 } 407 408 static void ipcomp6_destroy(struct xfrm_state *x) 409 { 410 struct ipcomp_data *ipcd = x->data; 411 if (!ipcd) 412 return; 413 xfrm_state_delete_tunnel(x); 414 mutex_lock(&ipcomp6_resource_mutex); 415 ipcomp6_free_data(ipcd); 416 mutex_unlock(&ipcomp6_resource_mutex); 417 kfree(ipcd); 418 419 xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr); 420 } 421 422 static int ipcomp6_init_state(struct xfrm_state *x) 423 { 424 int err; 425 struct ipcomp_data *ipcd; 426 struct xfrm_algo_desc *calg_desc; 427 428 err = -EINVAL; 429 if (!x->calg) 430 goto out; 431 432 if (x->encap) 433 goto out; 434 435 err = -ENOMEM; 436 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL); 437 if (!ipcd) 438 goto out; 439 440 x->props.header_len = 0; 441 if (x->props.mode) 442 x->props.header_len += sizeof(struct ipv6hdr); 443 444 mutex_lock(&ipcomp6_resource_mutex); 445 if (!ipcomp6_alloc_scratches()) 446 goto error; 447 448 ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name); 449 if (!ipcd->tfms) 450 goto error; 451 mutex_unlock(&ipcomp6_resource_mutex); 452 453 if (x->props.mode) { 454 err = ipcomp6_tunnel_attach(x); 455 if (err) 456 goto error_tunnel; 457 } 458 459 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0); 460 BUG_ON(!calg_desc); 461 ipcd->threshold = calg_desc->uinfo.comp.threshold; 462 x->data = ipcd; 463 err = 0; 464 out: 465 return err; 466 error_tunnel: 467 mutex_lock(&ipcomp6_resource_mutex); 468 error: 469 ipcomp6_free_data(ipcd); 470 mutex_unlock(&ipcomp6_resource_mutex); 471 kfree(ipcd); 472 473 goto out; 474 } 475 476 static struct xfrm_type ipcomp6_type = 477 { 478 .description = "IPCOMP6", 479 .owner = THIS_MODULE, 480 .proto = IPPROTO_COMP, 481 .init_state = ipcomp6_init_state, 482 .destructor = ipcomp6_destroy, 483 .input = ipcomp6_input, 484 .output = ipcomp6_output, 485 }; 486 487 static struct inet6_protocol ipcomp6_protocol = 488 { 489 .handler = xfrm6_rcv, 490 .err_handler = ipcomp6_err, 491 .flags = INET6_PROTO_NOPOLICY, 492 }; 493 494 static int __init ipcomp6_init(void) 495 { 496 if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) { 497 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n"); 498 return -EAGAIN; 499 } 500 if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) { 501 printk(KERN_INFO "ipcomp6 init: can't add protocol\n"); 502 xfrm_unregister_type(&ipcomp6_type, AF_INET6); 503 return -EAGAIN; 504 } 505 return 0; 506 } 507 508 static void __exit ipcomp6_fini(void) 509 { 510 if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) 511 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n"); 512 if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0) 513 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n"); 514 } 515 516 module_init(ipcomp6_init); 517 module_exit(ipcomp6_fini); 518 MODULE_LICENSE("GPL"); 519 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173"); 520 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>"); 521 522 523