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 <linux/ipv6.h> 51 #include <linux/icmpv6.h> 52 53 struct ipcomp6_tfms { 54 struct list_head list; 55 struct crypto_tfm **tfms; 56 int users; 57 }; 58 59 static DECLARE_MUTEX(ipcomp6_resource_sem); 60 static void **ipcomp6_scratches; 61 static int ipcomp6_scratch_users; 62 static LIST_HEAD(ipcomp6_tfms_list); 63 64 static int ipcomp6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb) 65 { 66 int err = 0; 67 u8 nexthdr = 0; 68 int hdr_len = skb->h.raw - skb->nh.raw; 69 unsigned char *tmp_hdr = NULL; 70 struct ipv6hdr *iph; 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_is_nonlinear(skb) || skb_cloned(skb)) && 78 skb_linearize(skb, GFP_ATOMIC) != 0) { 79 err = -ENOMEM; 80 goto out; 81 } 82 83 skb->ip_summed = CHECKSUM_NONE; 84 85 /* Remove ipcomp header and decompress original payload */ 86 iph = skb->nh.ipv6h; 87 tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC); 88 if (!tmp_hdr) 89 goto out; 90 memcpy(tmp_hdr, iph, hdr_len); 91 nexthdr = *(u8 *)skb->data; 92 skb_pull(skb, sizeof(struct ipv6_comp_hdr)); 93 skb->nh.raw += sizeof(struct ipv6_comp_hdr); 94 memcpy(skb->nh.raw, tmp_hdr, hdr_len); 95 iph = skb->nh.ipv6h; 96 iph->payload_len = htons(ntohs(iph->payload_len) - sizeof(struct ipv6_comp_hdr)); 97 skb->h.raw = skb->data; 98 99 /* decompression */ 100 plen = skb->len; 101 dlen = IPCOMP_SCRATCH_SIZE; 102 start = skb->data; 103 104 cpu = get_cpu(); 105 scratch = *per_cpu_ptr(ipcomp6_scratches, cpu); 106 tfm = *per_cpu_ptr(ipcd->tfms, cpu); 107 108 err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen); 109 if (err) { 110 err = -EINVAL; 111 goto out_put_cpu; 112 } 113 114 if (dlen < (plen + sizeof(struct ipv6_comp_hdr))) { 115 err = -EINVAL; 116 goto out_put_cpu; 117 } 118 119 err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC); 120 if (err) { 121 goto out_put_cpu; 122 } 123 124 skb_put(skb, dlen - plen); 125 memcpy(skb->data, scratch, dlen); 126 127 iph = skb->nh.ipv6h; 128 iph->payload_len = htons(skb->len); 129 130 out_put_cpu: 131 put_cpu(); 132 out: 133 kfree(tmp_hdr); 134 if (err) 135 goto error_out; 136 return nexthdr; 137 error_out: 138 return err; 139 } 140 141 static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb) 142 { 143 int err; 144 struct ipv6hdr *top_iph; 145 int hdr_len; 146 struct ipv6_comp_hdr *ipch; 147 struct ipcomp_data *ipcd = x->data; 148 int plen, dlen; 149 u8 *start, *scratch; 150 struct crypto_tfm *tfm; 151 int cpu; 152 153 hdr_len = skb->h.raw - skb->data; 154 155 /* check whether datagram len is larger than threshold */ 156 if ((skb->len - hdr_len) < ipcd->threshold) { 157 goto out_ok; 158 } 159 160 if ((skb_is_nonlinear(skb) || skb_cloned(skb)) && 161 skb_linearize(skb, GFP_ATOMIC) != 0) { 162 goto out_ok; 163 } 164 165 /* compression */ 166 plen = skb->len - hdr_len; 167 dlen = IPCOMP_SCRATCH_SIZE; 168 start = skb->h.raw; 169 170 cpu = get_cpu(); 171 scratch = *per_cpu_ptr(ipcomp6_scratches, cpu); 172 tfm = *per_cpu_ptr(ipcd->tfms, cpu); 173 174 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen); 175 if (err || (dlen + sizeof(struct ipv6_comp_hdr)) >= plen) { 176 put_cpu(); 177 goto out_ok; 178 } 179 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen); 180 put_cpu(); 181 pskb_trim(skb, hdr_len + dlen + sizeof(struct ip_comp_hdr)); 182 183 /* insert ipcomp header and replace datagram */ 184 top_iph = (struct ipv6hdr *)skb->data; 185 186 top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr)); 187 188 ipch = (struct ipv6_comp_hdr *)start; 189 ipch->nexthdr = *skb->nh.raw; 190 ipch->flags = 0; 191 ipch->cpi = htons((u16 )ntohl(x->id.spi)); 192 *skb->nh.raw = IPPROTO_COMP; 193 194 out_ok: 195 return 0; 196 } 197 198 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 199 int type, int code, int offset, __u32 info) 200 { 201 u32 spi; 202 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 203 struct ipv6_comp_hdr *ipcomph = (struct ipv6_comp_hdr*)(skb->data+offset); 204 struct xfrm_state *x; 205 206 if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG) 207 return; 208 209 spi = ntohl(ntohs(ipcomph->cpi)); 210 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6); 211 if (!x) 212 return; 213 214 printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" 215 "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n", 216 spi, NIP6(iph->daddr)); 217 xfrm_state_put(x); 218 } 219 220 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x) 221 { 222 struct xfrm_state *t = NULL; 223 224 t = xfrm_state_alloc(); 225 if (!t) 226 goto out; 227 228 t->id.proto = IPPROTO_IPV6; 229 t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr); 230 memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr)); 231 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 232 t->props.family = AF_INET6; 233 t->props.mode = 1; 234 memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr)); 235 236 if (xfrm_init_state(t)) 237 goto error; 238 239 atomic_set(&t->tunnel_users, 1); 240 241 out: 242 return t; 243 244 error: 245 xfrm_state_put(t); 246 goto out; 247 } 248 249 static int ipcomp6_tunnel_attach(struct xfrm_state *x) 250 { 251 int err = 0; 252 struct xfrm_state *t = NULL; 253 u32 spi; 254 255 spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr); 256 if (spi) 257 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr, 258 spi, IPPROTO_IPV6, AF_INET6); 259 if (!t) { 260 t = ipcomp6_tunnel_create(x); 261 if (!t) { 262 err = -EINVAL; 263 goto out; 264 } 265 xfrm_state_insert(t); 266 xfrm_state_hold(t); 267 } 268 x->tunnel = t; 269 atomic_inc(&t->tunnel_users); 270 271 out: 272 return err; 273 } 274 275 static void ipcomp6_free_scratches(void) 276 { 277 int i; 278 void **scratches; 279 280 if (--ipcomp6_scratch_users) 281 return; 282 283 scratches = ipcomp6_scratches; 284 if (!scratches) 285 return; 286 287 for_each_cpu(i) { 288 void *scratch = *per_cpu_ptr(scratches, i); 289 if (scratch) 290 vfree(scratch); 291 } 292 293 free_percpu(scratches); 294 } 295 296 static void **ipcomp6_alloc_scratches(void) 297 { 298 int i; 299 void **scratches; 300 301 if (ipcomp6_scratch_users++) 302 return ipcomp6_scratches; 303 304 scratches = alloc_percpu(void *); 305 if (!scratches) 306 return NULL; 307 308 ipcomp6_scratches = scratches; 309 310 for_each_cpu(i) { 311 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); 312 if (!scratch) 313 return NULL; 314 *per_cpu_ptr(scratches, i) = scratch; 315 } 316 317 return scratches; 318 } 319 320 static void ipcomp6_free_tfms(struct crypto_tfm **tfms) 321 { 322 struct ipcomp6_tfms *pos; 323 int cpu; 324 325 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 326 if (pos->tfms == tfms) 327 break; 328 } 329 330 BUG_TRAP(pos); 331 332 if (--pos->users) 333 return; 334 335 list_del(&pos->list); 336 kfree(pos); 337 338 if (!tfms) 339 return; 340 341 for_each_cpu(cpu) { 342 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu); 343 crypto_free_tfm(tfm); 344 } 345 free_percpu(tfms); 346 } 347 348 static struct crypto_tfm **ipcomp6_alloc_tfms(const char *alg_name) 349 { 350 struct ipcomp6_tfms *pos; 351 struct crypto_tfm **tfms; 352 int cpu; 353 354 /* This can be any valid CPU ID so we don't need locking. */ 355 cpu = raw_smp_processor_id(); 356 357 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 358 struct crypto_tfm *tfm; 359 360 tfms = pos->tfms; 361 tfm = *per_cpu_ptr(tfms, cpu); 362 363 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) { 364 pos->users++; 365 return tfms; 366 } 367 } 368 369 pos = kmalloc(sizeof(*pos), GFP_KERNEL); 370 if (!pos) 371 return NULL; 372 373 pos->users = 1; 374 INIT_LIST_HEAD(&pos->list); 375 list_add(&pos->list, &ipcomp6_tfms_list); 376 377 pos->tfms = tfms = alloc_percpu(struct crypto_tfm *); 378 if (!tfms) 379 goto error; 380 381 for_each_cpu(cpu) { 382 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0); 383 if (!tfm) 384 goto error; 385 *per_cpu_ptr(tfms, cpu) = tfm; 386 } 387 388 return tfms; 389 390 error: 391 ipcomp6_free_tfms(tfms); 392 return NULL; 393 } 394 395 static void ipcomp6_free_data(struct ipcomp_data *ipcd) 396 { 397 if (ipcd->tfms) 398 ipcomp6_free_tfms(ipcd->tfms); 399 ipcomp6_free_scratches(); 400 } 401 402 static void ipcomp6_destroy(struct xfrm_state *x) 403 { 404 struct ipcomp_data *ipcd = x->data; 405 if (!ipcd) 406 return; 407 xfrm_state_delete_tunnel(x); 408 down(&ipcomp6_resource_sem); 409 ipcomp6_free_data(ipcd); 410 up(&ipcomp6_resource_sem); 411 kfree(ipcd); 412 413 xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr); 414 } 415 416 static int ipcomp6_init_state(struct xfrm_state *x) 417 { 418 int err; 419 struct ipcomp_data *ipcd; 420 struct xfrm_algo_desc *calg_desc; 421 422 err = -EINVAL; 423 if (!x->calg) 424 goto out; 425 426 if (x->encap) 427 goto out; 428 429 err = -ENOMEM; 430 ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL); 431 if (!ipcd) 432 goto out; 433 434 memset(ipcd, 0, sizeof(*ipcd)); 435 x->props.header_len = 0; 436 if (x->props.mode) 437 x->props.header_len += sizeof(struct ipv6hdr); 438 439 down(&ipcomp6_resource_sem); 440 if (!ipcomp6_alloc_scratches()) 441 goto error; 442 443 ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name); 444 if (!ipcd->tfms) 445 goto error; 446 up(&ipcomp6_resource_sem); 447 448 if (x->props.mode) { 449 err = ipcomp6_tunnel_attach(x); 450 if (err) 451 goto error_tunnel; 452 } 453 454 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0); 455 BUG_ON(!calg_desc); 456 ipcd->threshold = calg_desc->uinfo.comp.threshold; 457 x->data = ipcd; 458 err = 0; 459 out: 460 return err; 461 error_tunnel: 462 down(&ipcomp6_resource_sem); 463 error: 464 ipcomp6_free_data(ipcd); 465 up(&ipcomp6_resource_sem); 466 kfree(ipcd); 467 468 goto out; 469 } 470 471 static struct xfrm_type ipcomp6_type = 472 { 473 .description = "IPCOMP6", 474 .owner = THIS_MODULE, 475 .proto = IPPROTO_COMP, 476 .init_state = ipcomp6_init_state, 477 .destructor = ipcomp6_destroy, 478 .input = ipcomp6_input, 479 .output = ipcomp6_output, 480 }; 481 482 static struct inet6_protocol ipcomp6_protocol = 483 { 484 .handler = xfrm6_rcv, 485 .err_handler = ipcomp6_err, 486 .flags = INET6_PROTO_NOPOLICY, 487 }; 488 489 static int __init ipcomp6_init(void) 490 { 491 if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) { 492 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n"); 493 return -EAGAIN; 494 } 495 if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) { 496 printk(KERN_INFO "ipcomp6 init: can't add protocol\n"); 497 xfrm_unregister_type(&ipcomp6_type, AF_INET6); 498 return -EAGAIN; 499 } 500 return 0; 501 } 502 503 static void __exit ipcomp6_fini(void) 504 { 505 if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) 506 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n"); 507 if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0) 508 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n"); 509 } 510 511 module_init(ipcomp6_init); 512 module_exit(ipcomp6_fini); 513 MODULE_LICENSE("GPL"); 514 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173"); 515 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>"); 516 517 518