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 if (xfrm_init_state(t)) 238 goto error; 239 240 atomic_set(&t->tunnel_users, 1); 241 242 out: 243 return t; 244 245 error: 246 xfrm_state_put(t); 247 goto out; 248 } 249 250 static int ipcomp6_tunnel_attach(struct xfrm_state *x) 251 { 252 int err = 0; 253 struct xfrm_state *t = NULL; 254 u32 spi; 255 256 spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr); 257 if (spi) 258 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr, 259 spi, IPPROTO_IPV6, AF_INET6); 260 if (!t) { 261 t = ipcomp6_tunnel_create(x); 262 if (!t) { 263 err = -EINVAL; 264 goto out; 265 } 266 xfrm_state_insert(t); 267 xfrm_state_hold(t); 268 } 269 x->tunnel = t; 270 atomic_inc(&t->tunnel_users); 271 272 out: 273 return err; 274 } 275 276 static void ipcomp6_free_scratches(void) 277 { 278 int i; 279 void **scratches; 280 281 if (--ipcomp6_scratch_users) 282 return; 283 284 scratches = ipcomp6_scratches; 285 if (!scratches) 286 return; 287 288 for_each_cpu(i) { 289 void *scratch = *per_cpu_ptr(scratches, i); 290 if (scratch) 291 vfree(scratch); 292 } 293 294 free_percpu(scratches); 295 } 296 297 static void **ipcomp6_alloc_scratches(void) 298 { 299 int i; 300 void **scratches; 301 302 if (ipcomp6_scratch_users++) 303 return ipcomp6_scratches; 304 305 scratches = alloc_percpu(void *); 306 if (!scratches) 307 return NULL; 308 309 ipcomp6_scratches = scratches; 310 311 for_each_cpu(i) { 312 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); 313 if (!scratch) 314 return NULL; 315 *per_cpu_ptr(scratches, i) = scratch; 316 } 317 318 return scratches; 319 } 320 321 static void ipcomp6_free_tfms(struct crypto_tfm **tfms) 322 { 323 struct ipcomp6_tfms *pos; 324 int cpu; 325 326 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 327 if (pos->tfms == tfms) 328 break; 329 } 330 331 BUG_TRAP(pos); 332 333 if (--pos->users) 334 return; 335 336 list_del(&pos->list); 337 kfree(pos); 338 339 if (!tfms) 340 return; 341 342 for_each_cpu(cpu) { 343 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu); 344 crypto_free_tfm(tfm); 345 } 346 free_percpu(tfms); 347 } 348 349 static struct crypto_tfm **ipcomp6_alloc_tfms(const char *alg_name) 350 { 351 struct ipcomp6_tfms *pos; 352 struct crypto_tfm **tfms; 353 int cpu; 354 355 /* This can be any valid CPU ID so we don't need locking. */ 356 cpu = raw_smp_processor_id(); 357 358 list_for_each_entry(pos, &ipcomp6_tfms_list, list) { 359 struct crypto_tfm *tfm; 360 361 tfms = pos->tfms; 362 tfm = *per_cpu_ptr(tfms, cpu); 363 364 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) { 365 pos->users++; 366 return tfms; 367 } 368 } 369 370 pos = kmalloc(sizeof(*pos), GFP_KERNEL); 371 if (!pos) 372 return NULL; 373 374 pos->users = 1; 375 INIT_LIST_HEAD(&pos->list); 376 list_add(&pos->list, &ipcomp6_tfms_list); 377 378 pos->tfms = tfms = alloc_percpu(struct crypto_tfm *); 379 if (!tfms) 380 goto error; 381 382 for_each_cpu(cpu) { 383 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0); 384 if (!tfm) 385 goto error; 386 *per_cpu_ptr(tfms, cpu) = tfm; 387 } 388 389 return tfms; 390 391 error: 392 ipcomp6_free_tfms(tfms); 393 return NULL; 394 } 395 396 static void ipcomp6_free_data(struct ipcomp_data *ipcd) 397 { 398 if (ipcd->tfms) 399 ipcomp6_free_tfms(ipcd->tfms); 400 ipcomp6_free_scratches(); 401 } 402 403 static void ipcomp6_destroy(struct xfrm_state *x) 404 { 405 struct ipcomp_data *ipcd = x->data; 406 if (!ipcd) 407 return; 408 xfrm_state_delete_tunnel(x); 409 down(&ipcomp6_resource_sem); 410 ipcomp6_free_data(ipcd); 411 up(&ipcomp6_resource_sem); 412 kfree(ipcd); 413 414 xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr); 415 } 416 417 static int ipcomp6_init_state(struct xfrm_state *x) 418 { 419 int err; 420 struct ipcomp_data *ipcd; 421 struct xfrm_algo_desc *calg_desc; 422 423 err = -EINVAL; 424 if (!x->calg) 425 goto out; 426 427 if (x->encap) 428 goto out; 429 430 err = -ENOMEM; 431 ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL); 432 if (!ipcd) 433 goto out; 434 435 memset(ipcd, 0, sizeof(*ipcd)); 436 x->props.header_len = 0; 437 if (x->props.mode) 438 x->props.header_len += sizeof(struct ipv6hdr); 439 440 down(&ipcomp6_resource_sem); 441 if (!ipcomp6_alloc_scratches()) 442 goto error; 443 444 ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name); 445 if (!ipcd->tfms) 446 goto error; 447 up(&ipcomp6_resource_sem); 448 449 if (x->props.mode) { 450 err = ipcomp6_tunnel_attach(x); 451 if (err) 452 goto error_tunnel; 453 } 454 455 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0); 456 BUG_ON(!calg_desc); 457 ipcd->threshold = calg_desc->uinfo.comp.threshold; 458 x->data = ipcd; 459 err = 0; 460 out: 461 return err; 462 error_tunnel: 463 down(&ipcomp6_resource_sem); 464 error: 465 ipcomp6_free_data(ipcd); 466 up(&ipcomp6_resource_sem); 467 kfree(ipcd); 468 469 goto out; 470 } 471 472 static struct xfrm_type ipcomp6_type = 473 { 474 .description = "IPCOMP6", 475 .owner = THIS_MODULE, 476 .proto = IPPROTO_COMP, 477 .init_state = ipcomp6_init_state, 478 .destructor = ipcomp6_destroy, 479 .input = ipcomp6_input, 480 .output = ipcomp6_output, 481 }; 482 483 static struct inet6_protocol ipcomp6_protocol = 484 { 485 .handler = xfrm6_rcv, 486 .err_handler = ipcomp6_err, 487 .flags = INET6_PROTO_NOPOLICY, 488 }; 489 490 static int __init ipcomp6_init(void) 491 { 492 if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) { 493 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n"); 494 return -EAGAIN; 495 } 496 if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) { 497 printk(KERN_INFO "ipcomp6 init: can't add protocol\n"); 498 xfrm_unregister_type(&ipcomp6_type, AF_INET6); 499 return -EAGAIN; 500 } 501 return 0; 502 } 503 504 static void __exit ipcomp6_fini(void) 505 { 506 if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) 507 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n"); 508 if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0) 509 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n"); 510 } 511 512 module_init(ipcomp6_init); 513 module_exit(ipcomp6_fini); 514 MODULE_LICENSE("GPL"); 515 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173"); 516 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>"); 517 518 519