ipcomp.c revision 0da974f4f303a6842516b764507e3c0a03f41e5a
1/* 2 * IP Payload Compression Protocol (IPComp) - RFC3173. 3 * 4 * Copyright (c) 2003 James Morris <jmorris@intercode.com.au> 5 * 6 * This program is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License as published by the Free 8 * Software Foundation; either version 2 of the License, or (at your option) 9 * any later version. 10 * 11 * Todo: 12 * - Tunable compression parameters. 13 * - Compression stats. 14 * - Adaptive compression. 15 */ 16#include <linux/module.h> 17#include <asm/scatterlist.h> 18#include <asm/semaphore.h> 19#include <linux/crypto.h> 20#include <linux/pfkeyv2.h> 21#include <linux/percpu.h> 22#include <linux/smp.h> 23#include <linux/list.h> 24#include <linux/vmalloc.h> 25#include <linux/rtnetlink.h> 26#include <linux/mutex.h> 27#include <net/ip.h> 28#include <net/xfrm.h> 29#include <net/icmp.h> 30#include <net/ipcomp.h> 31#include <net/protocol.h> 32 33struct ipcomp_tfms { 34 struct list_head list; 35 struct crypto_tfm **tfms; 36 int users; 37}; 38 39static DEFINE_MUTEX(ipcomp_resource_mutex); 40static void **ipcomp_scratches; 41static int ipcomp_scratch_users; 42static LIST_HEAD(ipcomp_tfms_list); 43 44static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb) 45{ 46 int err, plen, dlen; 47 struct ipcomp_data *ipcd = x->data; 48 u8 *start, *scratch; 49 struct crypto_tfm *tfm; 50 int cpu; 51 52 plen = skb->len; 53 dlen = IPCOMP_SCRATCH_SIZE; 54 start = skb->data; 55 56 cpu = get_cpu(); 57 scratch = *per_cpu_ptr(ipcomp_scratches, cpu); 58 tfm = *per_cpu_ptr(ipcd->tfms, cpu); 59 60 err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen); 61 if (err) 62 goto out; 63 64 if (dlen < (plen + sizeof(struct ip_comp_hdr))) { 65 err = -EINVAL; 66 goto out; 67 } 68 69 err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC); 70 if (err) 71 goto out; 72 73 skb->truesize += dlen - plen; 74 __skb_put(skb, dlen - plen); 75 memcpy(skb->data, scratch, dlen); 76out: 77 put_cpu(); 78 return err; 79} 80 81static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb) 82{ 83 int err = -ENOMEM; 84 struct iphdr *iph; 85 struct ip_comp_hdr *ipch; 86 87 if (skb_linearize_cow(skb)) 88 goto out; 89 90 skb->ip_summed = CHECKSUM_NONE; 91 92 /* Remove ipcomp header and decompress original payload */ 93 iph = skb->nh.iph; 94 ipch = (void *)skb->data; 95 iph->protocol = ipch->nexthdr; 96 skb->h.raw = skb->nh.raw + sizeof(*ipch); 97 __skb_pull(skb, sizeof(*ipch)); 98 err = ipcomp_decompress(x, skb); 99 100out: 101 return err; 102} 103 104static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb) 105{ 106 int err, plen, dlen, ihlen; 107 struct iphdr *iph = skb->nh.iph; 108 struct ipcomp_data *ipcd = x->data; 109 u8 *start, *scratch; 110 struct crypto_tfm *tfm; 111 int cpu; 112 113 ihlen = iph->ihl * 4; 114 plen = skb->len - ihlen; 115 dlen = IPCOMP_SCRATCH_SIZE; 116 start = skb->data + ihlen; 117 118 cpu = get_cpu(); 119 scratch = *per_cpu_ptr(ipcomp_scratches, cpu); 120 tfm = *per_cpu_ptr(ipcd->tfms, cpu); 121 122 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen); 123 if (err) 124 goto out; 125 126 if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) { 127 err = -EMSGSIZE; 128 goto out; 129 } 130 131 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen); 132 put_cpu(); 133 134 pskb_trim(skb, ihlen + dlen + sizeof(struct ip_comp_hdr)); 135 return 0; 136 137out: 138 put_cpu(); 139 return err; 140} 141 142static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb) 143{ 144 int err; 145 struct iphdr *iph; 146 struct ip_comp_hdr *ipch; 147 struct ipcomp_data *ipcd = x->data; 148 int hdr_len = 0; 149 150 iph = skb->nh.iph; 151 iph->tot_len = htons(skb->len); 152 hdr_len = iph->ihl * 4; 153 if ((skb->len - hdr_len) < ipcd->threshold) { 154 /* Don't bother compressing */ 155 goto out_ok; 156 } 157 158 if (skb_linearize_cow(skb)) 159 goto out_ok; 160 161 err = ipcomp_compress(x, skb); 162 iph = skb->nh.iph; 163 164 if (err) { 165 goto out_ok; 166 } 167 168 /* Install ipcomp header, convert into ipcomp datagram. */ 169 iph->tot_len = htons(skb->len); 170 ipch = (struct ip_comp_hdr *)((char *)iph + iph->ihl * 4); 171 ipch->nexthdr = iph->protocol; 172 ipch->flags = 0; 173 ipch->cpi = htons((u16 )ntohl(x->id.spi)); 174 iph->protocol = IPPROTO_COMP; 175 ip_send_check(iph); 176 return 0; 177 178out_ok: 179 if (x->props.mode) 180 ip_send_check(iph); 181 return 0; 182} 183 184static void ipcomp4_err(struct sk_buff *skb, u32 info) 185{ 186 u32 spi; 187 struct iphdr *iph = (struct iphdr *)skb->data; 188 struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2)); 189 struct xfrm_state *x; 190 191 if (skb->h.icmph->type != ICMP_DEST_UNREACH || 192 skb->h.icmph->code != ICMP_FRAG_NEEDED) 193 return; 194 195 spi = htonl(ntohs(ipch->cpi)); 196 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, 197 spi, IPPROTO_COMP, AF_INET); 198 if (!x) 199 return; 200 NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n", 201 spi, NIPQUAD(iph->daddr)); 202 xfrm_state_put(x); 203} 204 205/* We always hold one tunnel user reference to indicate a tunnel */ 206static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x) 207{ 208 struct xfrm_state *t; 209 210 t = xfrm_state_alloc(); 211 if (t == NULL) 212 goto out; 213 214 t->id.proto = IPPROTO_IPIP; 215 t->id.spi = x->props.saddr.a4; 216 t->id.daddr.a4 = x->id.daddr.a4; 217 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 218 t->props.family = AF_INET; 219 t->props.mode = 1; 220 t->props.saddr.a4 = x->props.saddr.a4; 221 t->props.flags = x->props.flags; 222 223 if (xfrm_init_state(t)) 224 goto error; 225 226 atomic_set(&t->tunnel_users, 1); 227out: 228 return t; 229 230error: 231 t->km.state = XFRM_STATE_DEAD; 232 xfrm_state_put(t); 233 t = NULL; 234 goto out; 235} 236 237/* 238 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are 239 * always incremented on success. 240 */ 241static int ipcomp_tunnel_attach(struct xfrm_state *x) 242{ 243 int err = 0; 244 struct xfrm_state *t; 245 246 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4, 247 x->props.saddr.a4, IPPROTO_IPIP, AF_INET); 248 if (!t) { 249 t = ipcomp_tunnel_create(x); 250 if (!t) { 251 err = -EINVAL; 252 goto out; 253 } 254 xfrm_state_insert(t); 255 xfrm_state_hold(t); 256 } 257 x->tunnel = t; 258 atomic_inc(&t->tunnel_users); 259out: 260 return err; 261} 262 263static void ipcomp_free_scratches(void) 264{ 265 int i; 266 void **scratches; 267 268 if (--ipcomp_scratch_users) 269 return; 270 271 scratches = ipcomp_scratches; 272 if (!scratches) 273 return; 274 275 for_each_possible_cpu(i) 276 vfree(*per_cpu_ptr(scratches, i)); 277 278 free_percpu(scratches); 279} 280 281static void **ipcomp_alloc_scratches(void) 282{ 283 int i; 284 void **scratches; 285 286 if (ipcomp_scratch_users++) 287 return ipcomp_scratches; 288 289 scratches = alloc_percpu(void *); 290 if (!scratches) 291 return NULL; 292 293 ipcomp_scratches = scratches; 294 295 for_each_possible_cpu(i) { 296 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); 297 if (!scratch) 298 return NULL; 299 *per_cpu_ptr(scratches, i) = scratch; 300 } 301 302 return scratches; 303} 304 305static void ipcomp_free_tfms(struct crypto_tfm **tfms) 306{ 307 struct ipcomp_tfms *pos; 308 int cpu; 309 310 list_for_each_entry(pos, &ipcomp_tfms_list, list) { 311 if (pos->tfms == tfms) 312 break; 313 } 314 315 BUG_TRAP(pos); 316 317 if (--pos->users) 318 return; 319 320 list_del(&pos->list); 321 kfree(pos); 322 323 if (!tfms) 324 return; 325 326 for_each_possible_cpu(cpu) { 327 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu); 328 crypto_free_tfm(tfm); 329 } 330 free_percpu(tfms); 331} 332 333static struct crypto_tfm **ipcomp_alloc_tfms(const char *alg_name) 334{ 335 struct ipcomp_tfms *pos; 336 struct crypto_tfm **tfms; 337 int cpu; 338 339 /* This can be any valid CPU ID so we don't need locking. */ 340 cpu = raw_smp_processor_id(); 341 342 list_for_each_entry(pos, &ipcomp_tfms_list, list) { 343 struct crypto_tfm *tfm; 344 345 tfms = pos->tfms; 346 tfm = *per_cpu_ptr(tfms, cpu); 347 348 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) { 349 pos->users++; 350 return tfms; 351 } 352 } 353 354 pos = kmalloc(sizeof(*pos), GFP_KERNEL); 355 if (!pos) 356 return NULL; 357 358 pos->users = 1; 359 INIT_LIST_HEAD(&pos->list); 360 list_add(&pos->list, &ipcomp_tfms_list); 361 362 pos->tfms = tfms = alloc_percpu(struct crypto_tfm *); 363 if (!tfms) 364 goto error; 365 366 for_each_possible_cpu(cpu) { 367 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0); 368 if (!tfm) 369 goto error; 370 *per_cpu_ptr(tfms, cpu) = tfm; 371 } 372 373 return tfms; 374 375error: 376 ipcomp_free_tfms(tfms); 377 return NULL; 378} 379 380static void ipcomp_free_data(struct ipcomp_data *ipcd) 381{ 382 if (ipcd->tfms) 383 ipcomp_free_tfms(ipcd->tfms); 384 ipcomp_free_scratches(); 385} 386 387static void ipcomp_destroy(struct xfrm_state *x) 388{ 389 struct ipcomp_data *ipcd = x->data; 390 if (!ipcd) 391 return; 392 xfrm_state_delete_tunnel(x); 393 mutex_lock(&ipcomp_resource_mutex); 394 ipcomp_free_data(ipcd); 395 mutex_unlock(&ipcomp_resource_mutex); 396 kfree(ipcd); 397} 398 399static int ipcomp_init_state(struct xfrm_state *x) 400{ 401 int err; 402 struct ipcomp_data *ipcd; 403 struct xfrm_algo_desc *calg_desc; 404 405 err = -EINVAL; 406 if (!x->calg) 407 goto out; 408 409 if (x->encap) 410 goto out; 411 412 err = -ENOMEM; 413 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL); 414 if (!ipcd) 415 goto out; 416 417 x->props.header_len = 0; 418 if (x->props.mode) 419 x->props.header_len += sizeof(struct iphdr); 420 421 mutex_lock(&ipcomp_resource_mutex); 422 if (!ipcomp_alloc_scratches()) 423 goto error; 424 425 ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name); 426 if (!ipcd->tfms) 427 goto error; 428 mutex_unlock(&ipcomp_resource_mutex); 429 430 if (x->props.mode) { 431 err = ipcomp_tunnel_attach(x); 432 if (err) 433 goto error_tunnel; 434 } 435 436 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0); 437 BUG_ON(!calg_desc); 438 ipcd->threshold = calg_desc->uinfo.comp.threshold; 439 x->data = ipcd; 440 err = 0; 441out: 442 return err; 443 444error_tunnel: 445 mutex_lock(&ipcomp_resource_mutex); 446error: 447 ipcomp_free_data(ipcd); 448 mutex_unlock(&ipcomp_resource_mutex); 449 kfree(ipcd); 450 goto out; 451} 452 453static struct xfrm_type ipcomp_type = { 454 .description = "IPCOMP4", 455 .owner = THIS_MODULE, 456 .proto = IPPROTO_COMP, 457 .init_state = ipcomp_init_state, 458 .destructor = ipcomp_destroy, 459 .input = ipcomp_input, 460 .output = ipcomp_output 461}; 462 463static struct net_protocol ipcomp4_protocol = { 464 .handler = xfrm4_rcv, 465 .err_handler = ipcomp4_err, 466 .no_policy = 1, 467}; 468 469static int __init ipcomp4_init(void) 470{ 471 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) { 472 printk(KERN_INFO "ipcomp init: can't add xfrm type\n"); 473 return -EAGAIN; 474 } 475 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) { 476 printk(KERN_INFO "ipcomp init: can't add protocol\n"); 477 xfrm_unregister_type(&ipcomp_type, AF_INET); 478 return -EAGAIN; 479 } 480 return 0; 481} 482 483static void __exit ipcomp4_fini(void) 484{ 485 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) 486 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n"); 487 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0) 488 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n"); 489} 490 491module_init(ipcomp4_init); 492module_exit(ipcomp4_fini); 493 494MODULE_LICENSE("GPL"); 495MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173"); 496MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); 497 498