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 if (tmp_hdr) 134 kfree(tmp_hdr); 135 if (err) 136 goto error_out; 137 return nexthdr; 138 error_out: 139 return err; 140 } 141 142 static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb) 143 { 144 int err; 145 struct ipv6hdr *top_iph; 146 int hdr_len; 147 struct ipv6_comp_hdr *ipch; 148 struct ipcomp_data *ipcd = x->data; 149 int plen, dlen; 150 u8 *start, *scratch; 151 struct crypto_tfm *tfm; 152 int cpu; 153 154 hdr_len = skb->h.raw - skb->data; 155 156 /* check whether datagram len is larger than threshold */ 157 if ((skb->len - hdr_len) < ipcd->threshold) { 158 goto out_ok; 159 } 160 161 if ((skb_is_nonlinear(skb) || skb_cloned(skb)) && 162 skb_linearize(skb, GFP_ATOMIC) != 0) { 163 goto out_ok; 164 } 165 166 /* compression */ 167 plen = skb->len - hdr_len; 168 dlen = IPCOMP_SCRATCH_SIZE; 169 start = skb->h.raw; 170 171 cpu = get_cpu(); 172 scratch = *per_cpu_ptr(ipcomp6_scratches, cpu); 173 tfm = *per_cpu_ptr(ipcd->tfms, cpu); 174 175 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen); 176 if (err || (dlen + sizeof(struct ipv6_comp_hdr)) >= plen) { 177 put_cpu(); 178 goto out_ok; 179 } 180 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen); 181 put_cpu(); 182 pskb_trim(skb, hdr_len + dlen + sizeof(struct ip_comp_hdr)); 183 184 /* insert ipcomp header and replace datagram */ 185 top_iph = (struct ipv6hdr *)skb->data; 186 187 top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr)); 188 189 ipch = (struct ipv6_comp_hdr *)start; 190 ipch->nexthdr = *skb->nh.raw; 191 ipch->flags = 0; 192 ipch->cpi = htons((u16 )ntohl(x->id.spi)); 193 *skb->nh.raw = IPPROTO_COMP; 194 195 out_ok: 196 return 0; 197 } 198 199 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 200 int type, int code, int offset, __u32 info) 201 { 202 u32 spi; 203 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 204 struct ipv6_comp_hdr *ipcomph = (struct ipv6_comp_hdr*)(skb->data+offset); 205 struct xfrm_state *x; 206 207 if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG) 208 return; 209 210 spi = ntohl(ntohs(ipcomph->cpi)); 211 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6); 212 if (!x) 213 return; 214 215 printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" 216 "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\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 memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr)); 232 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 233 t->props.family = AF_INET6; 234 t->props.mode = 1; 235 memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr)); 236 237 t->type = xfrm_get_type(IPPROTO_IPV6, t->props.family); 238 if (t->type == NULL) 239 goto error; 240 241 if (t->type->init_state(t, NULL)) 242 goto error; 243 244 t->km.state = XFRM_STATE_VALID; 245 atomic_set(&t->tunnel_users, 1); 246 247 out: 248 return t; 249 250 error: 251 xfrm_state_put(t); 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_cpu(i) { 294 void *scratch = *per_cpu_ptr(scratches, i); 295 if (scratch) 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_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_cpu(cpu) { 348 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu); 349 if (tfm) 350 crypto_free_tfm(tfm); 351 } 352 free_percpu(tfms); 353 } 354 355 static struct crypto_tfm **ipcomp6_alloc_tfms(const char *alg_name) 356 { 357 struct ipcomp6_tfms *pos; 358 struct crypto_tfm **tfms; 359 int cpu; 360 361 /* This can be any valid CPU ID so we don't need locking. */ 362 cpu = smp_processor_id(); 363 364 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 365 struct crypto_tfm *tfm; 366 367 tfms = pos->tfms; 368 tfm = *per_cpu_ptr(tfms, cpu); 369 370 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) { 371 pos->users++; 372 return tfms; 373 } 374 } 375 376 pos = kmalloc(sizeof(*pos), GFP_KERNEL); 377 if (!pos) 378 return NULL; 379 380 pos->users = 1; 381 INIT_LIST_HEAD(&pos->list); 382 list_add(&pos->list, &ipcomp6_tfms_list); 383 384 pos->tfms = tfms = alloc_percpu(struct crypto_tfm *); 385 if (!tfms) 386 goto error; 387 388 for_each_cpu(cpu) { 389 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0); 390 if (!tfm) 391 goto error; 392 *per_cpu_ptr(tfms, cpu) = tfm; 393 } 394 395 return tfms; 396 397 error: 398 ipcomp6_free_tfms(tfms); 399 return NULL; 400 } 401 402 static void ipcomp6_free_data(struct ipcomp_data *ipcd) 403 { 404 if (ipcd->tfms) 405 ipcomp6_free_tfms(ipcd->tfms); 406 ipcomp6_free_scratches(); 407 } 408 409 static void ipcomp6_destroy(struct xfrm_state *x) 410 { 411 struct ipcomp_data *ipcd = x->data; 412 if (!ipcd) 413 return; 414 xfrm_state_delete_tunnel(x); 415 down(&ipcomp6_resource_sem); 416 ipcomp6_free_data(ipcd); 417 up(&ipcomp6_resource_sem); 418 kfree(ipcd); 419 420 xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr); 421 } 422 423 static int ipcomp6_init_state(struct xfrm_state *x, void *args) 424 { 425 int err; 426 struct ipcomp_data *ipcd; 427 struct xfrm_algo_desc *calg_desc; 428 429 err = -EINVAL; 430 if (!x->calg) 431 goto out; 432 433 if (x->encap) 434 goto out; 435 436 err = -ENOMEM; 437 ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL); 438 if (!ipcd) 439 goto out; 440 441 memset(ipcd, 0, sizeof(*ipcd)); 442 x->props.header_len = 0; 443 if (x->props.mode) 444 x->props.header_len += sizeof(struct ipv6hdr); 445 446 down(&ipcomp6_resource_sem); 447 if (!ipcomp6_alloc_scratches()) 448 goto error; 449 450 ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name); 451 if (!ipcd->tfms) 452 goto error; 453 up(&ipcomp6_resource_sem); 454 455 if (x->props.mode) { 456 err = ipcomp6_tunnel_attach(x); 457 if (err) 458 goto error_tunnel; 459 } 460 461 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0); 462 BUG_ON(!calg_desc); 463 ipcd->threshold = calg_desc->uinfo.comp.threshold; 464 x->data = ipcd; 465 err = 0; 466 out: 467 return err; 468 error_tunnel: 469 down(&ipcomp6_resource_sem); 470 error: 471 ipcomp6_free_data(ipcd); 472 up(&ipcomp6_resource_sem); 473 kfree(ipcd); 474 475 goto out; 476 } 477 478 static struct xfrm_type ipcomp6_type = 479 { 480 .description = "IPCOMP6", 481 .owner = THIS_MODULE, 482 .proto = IPPROTO_COMP, 483 .init_state = ipcomp6_init_state, 484 .destructor = ipcomp6_destroy, 485 .input = ipcomp6_input, 486 .output = ipcomp6_output, 487 }; 488 489 static struct inet6_protocol ipcomp6_protocol = 490 { 491 .handler = xfrm6_rcv, 492 .err_handler = ipcomp6_err, 493 .flags = INET6_PROTO_NOPOLICY, 494 }; 495 496 static int __init ipcomp6_init(void) 497 { 498 if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) { 499 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n"); 500 return -EAGAIN; 501 } 502 if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) { 503 printk(KERN_INFO "ipcomp6 init: can't add protocol\n"); 504 xfrm_unregister_type(&ipcomp6_type, AF_INET6); 505 return -EAGAIN; 506 } 507 return 0; 508 } 509 510 static void __exit ipcomp6_fini(void) 511 { 512 if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) 513 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n"); 514 if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0) 515 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n"); 516 } 517 518 module_init(ipcomp6_init); 519 module_exit(ipcomp6_fini); 520 MODULE_LICENSE("GPL"); 521 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173"); 522 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>"); 523 524 525