ipcomp.c revision 87bdc48d304191313203df9b98d783e1ab5a55ab
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_comp **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 struct ipcomp_data *ipcd = x->data; 47 const int plen = skb->len; 48 int dlen = IPCOMP_SCRATCH_SIZE; 49 const u8 *start = skb->data; 50 const int cpu = get_cpu(); 51 u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu); 52 struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu); 53 int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen); 54 55 if (err) 56 goto out; 57 58 if (dlen < (plen + sizeof(struct ip_comp_hdr))) { 59 err = -EINVAL; 60 goto out; 61 } 62 63 err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC); 64 if (err) 65 goto out; 66 67 skb->truesize += dlen - plen; 68 __skb_put(skb, dlen - plen); 69 skb_copy_to_linear_data(skb, scratch, dlen); 70out: 71 put_cpu(); 72 return err; 73} 74 75static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb) 76{ 77 int err = -ENOMEM; 78 struct iphdr *iph; 79 struct ip_comp_hdr *ipch; 80 81 if (skb_linearize_cow(skb)) 82 goto out; 83 84 skb->ip_summed = CHECKSUM_NONE; 85 86 /* Remove ipcomp header and decompress original payload */ 87 iph = ip_hdr(skb); 88 ipch = (void *)skb->data; 89 iph->protocol = ipch->nexthdr; 90 skb->transport_header = skb->network_header + sizeof(*ipch); 91 __skb_pull(skb, sizeof(*ipch)); 92 err = ipcomp_decompress(x, skb); 93 94out: 95 return err; 96} 97 98static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb) 99{ 100 struct ipcomp_data *ipcd = x->data; 101 const int ihlen = skb_transport_offset(skb); 102 const int plen = skb->len - ihlen; 103 int dlen = IPCOMP_SCRATCH_SIZE; 104 u8 *start = skb_transport_header(skb); 105 const int cpu = get_cpu(); 106 u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu); 107 struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu); 108 int err = crypto_comp_compress(tfm, start, plen, scratch, &dlen); 109 110 if (err) 111 goto out; 112 113 if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) { 114 err = -EMSGSIZE; 115 goto out; 116 } 117 118 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen); 119 put_cpu(); 120 121 pskb_trim(skb, ihlen + dlen + sizeof(struct ip_comp_hdr)); 122 return 0; 123 124out: 125 put_cpu(); 126 return err; 127} 128 129static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb) 130{ 131 int err; 132 struct ip_comp_hdr *ipch; 133 struct ipcomp_data *ipcd = x->data; 134 int hdr_len = 0; 135 struct iphdr *iph = ip_hdr(skb); 136 137 skb_push(skb, -skb_network_offset(skb)); 138 iph->tot_len = htons(skb->len); 139 hdr_len = iph->ihl * 4; 140 if ((skb->len - hdr_len) < ipcd->threshold) { 141 /* Don't bother compressing */ 142 goto out_ok; 143 } 144 145 if (skb_linearize_cow(skb)) 146 goto out_ok; 147 148 err = ipcomp_compress(x, skb); 149 iph = ip_hdr(skb); 150 151 if (err) { 152 goto out_ok; 153 } 154 155 /* Install ipcomp header, convert into ipcomp datagram. */ 156 iph->tot_len = htons(skb->len); 157 ipch = ip_comp_hdr(skb); 158 ipch->nexthdr = *skb_mac_header(skb); 159 ipch->flags = 0; 160 ipch->cpi = htons((u16 )ntohl(x->id.spi)); 161 *skb_mac_header(skb) = IPPROTO_COMP; 162 ip_send_check(iph); 163 return 0; 164 165out_ok: 166 if (x->props.mode == XFRM_MODE_TUNNEL) 167 ip_send_check(iph); 168 return 0; 169} 170 171static void ipcomp4_err(struct sk_buff *skb, u32 info) 172{ 173 __be32 spi; 174 struct iphdr *iph = (struct iphdr *)skb->data; 175 struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2)); 176 struct xfrm_state *x; 177 178 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH || 179 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) 180 return; 181 182 spi = htonl(ntohs(ipch->cpi)); 183 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, 184 spi, IPPROTO_COMP, AF_INET); 185 if (!x) 186 return; 187 NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n", 188 spi, NIPQUAD(iph->daddr)); 189 xfrm_state_put(x); 190} 191 192/* We always hold one tunnel user reference to indicate a tunnel */ 193static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x) 194{ 195 struct xfrm_state *t; 196 u8 mode = XFRM_MODE_TUNNEL; 197 198 t = xfrm_state_alloc(); 199 if (t == NULL) 200 goto out; 201 202 t->id.proto = IPPROTO_IPIP; 203 t->id.spi = x->props.saddr.a4; 204 t->id.daddr.a4 = x->id.daddr.a4; 205 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 206 t->props.family = AF_INET; 207 if (x->props.mode == XFRM_MODE_BEET) 208 mode = x->props.mode; 209 t->props.mode = mode; 210 t->props.saddr.a4 = x->props.saddr.a4; 211 t->props.flags = x->props.flags; 212 213 if (xfrm_init_state(t)) 214 goto error; 215 216 atomic_set(&t->tunnel_users, 1); 217out: 218 return t; 219 220error: 221 t->km.state = XFRM_STATE_DEAD; 222 xfrm_state_put(t); 223 t = NULL; 224 goto out; 225} 226 227/* 228 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are 229 * always incremented on success. 230 */ 231static int ipcomp_tunnel_attach(struct xfrm_state *x) 232{ 233 int err = 0; 234 struct xfrm_state *t; 235 236 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4, 237 x->props.saddr.a4, IPPROTO_IPIP, AF_INET); 238 if (!t) { 239 t = ipcomp_tunnel_create(x); 240 if (!t) { 241 err = -EINVAL; 242 goto out; 243 } 244 xfrm_state_insert(t); 245 xfrm_state_hold(t); 246 } 247 x->tunnel = t; 248 atomic_inc(&t->tunnel_users); 249out: 250 return err; 251} 252 253static void ipcomp_free_scratches(void) 254{ 255 int i; 256 void **scratches; 257 258 if (--ipcomp_scratch_users) 259 return; 260 261 scratches = ipcomp_scratches; 262 if (!scratches) 263 return; 264 265 for_each_possible_cpu(i) 266 vfree(*per_cpu_ptr(scratches, i)); 267 268 free_percpu(scratches); 269} 270 271static void **ipcomp_alloc_scratches(void) 272{ 273 int i; 274 void **scratches; 275 276 if (ipcomp_scratch_users++) 277 return ipcomp_scratches; 278 279 scratches = alloc_percpu(void *); 280 if (!scratches) 281 return NULL; 282 283 ipcomp_scratches = scratches; 284 285 for_each_possible_cpu(i) { 286 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); 287 if (!scratch) 288 return NULL; 289 *per_cpu_ptr(scratches, i) = scratch; 290 } 291 292 return scratches; 293} 294 295static void ipcomp_free_tfms(struct crypto_comp **tfms) 296{ 297 struct ipcomp_tfms *pos; 298 int cpu; 299 300 list_for_each_entry(pos, &ipcomp_tfms_list, list) { 301 if (pos->tfms == tfms) 302 break; 303 } 304 305 BUG_TRAP(pos); 306 307 if (--pos->users) 308 return; 309 310 list_del(&pos->list); 311 kfree(pos); 312 313 if (!tfms) 314 return; 315 316 for_each_possible_cpu(cpu) { 317 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu); 318 crypto_free_comp(tfm); 319 } 320 free_percpu(tfms); 321} 322 323static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name) 324{ 325 struct ipcomp_tfms *pos; 326 struct crypto_comp **tfms; 327 int cpu; 328 329 /* This can be any valid CPU ID so we don't need locking. */ 330 cpu = raw_smp_processor_id(); 331 332 list_for_each_entry(pos, &ipcomp_tfms_list, list) { 333 struct crypto_comp *tfm; 334 335 tfms = pos->tfms; 336 tfm = *per_cpu_ptr(tfms, cpu); 337 338 if (!strcmp(crypto_comp_name(tfm), alg_name)) { 339 pos->users++; 340 return tfms; 341 } 342 } 343 344 pos = kmalloc(sizeof(*pos), GFP_KERNEL); 345 if (!pos) 346 return NULL; 347 348 pos->users = 1; 349 INIT_LIST_HEAD(&pos->list); 350 list_add(&pos->list, &ipcomp_tfms_list); 351 352 pos->tfms = tfms = alloc_percpu(struct crypto_comp *); 353 if (!tfms) 354 goto error; 355 356 for_each_possible_cpu(cpu) { 357 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0, 358 CRYPTO_ALG_ASYNC); 359 if (!tfm) 360 goto error; 361 *per_cpu_ptr(tfms, cpu) = tfm; 362 } 363 364 return tfms; 365 366error: 367 ipcomp_free_tfms(tfms); 368 return NULL; 369} 370 371static void ipcomp_free_data(struct ipcomp_data *ipcd) 372{ 373 if (ipcd->tfms) 374 ipcomp_free_tfms(ipcd->tfms); 375 ipcomp_free_scratches(); 376} 377 378static void ipcomp_destroy(struct xfrm_state *x) 379{ 380 struct ipcomp_data *ipcd = x->data; 381 if (!ipcd) 382 return; 383 xfrm_state_delete_tunnel(x); 384 mutex_lock(&ipcomp_resource_mutex); 385 ipcomp_free_data(ipcd); 386 mutex_unlock(&ipcomp_resource_mutex); 387 kfree(ipcd); 388} 389 390static int ipcomp_init_state(struct xfrm_state *x) 391{ 392 int err; 393 struct ipcomp_data *ipcd; 394 struct xfrm_algo_desc *calg_desc; 395 396 err = -EINVAL; 397 if (!x->calg) 398 goto out; 399 400 if (x->encap) 401 goto out; 402 403 err = -ENOMEM; 404 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL); 405 if (!ipcd) 406 goto out; 407 408 x->props.header_len = 0; 409 if (x->props.mode == XFRM_MODE_TUNNEL) 410 x->props.header_len += sizeof(struct iphdr); 411 412 mutex_lock(&ipcomp_resource_mutex); 413 if (!ipcomp_alloc_scratches()) 414 goto error; 415 416 ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name); 417 if (!ipcd->tfms) 418 goto error; 419 mutex_unlock(&ipcomp_resource_mutex); 420 421 if (x->props.mode == XFRM_MODE_TUNNEL) { 422 err = ipcomp_tunnel_attach(x); 423 if (err) 424 goto error_tunnel; 425 } 426 427 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0); 428 BUG_ON(!calg_desc); 429 ipcd->threshold = calg_desc->uinfo.comp.threshold; 430 x->data = ipcd; 431 err = 0; 432out: 433 return err; 434 435error_tunnel: 436 mutex_lock(&ipcomp_resource_mutex); 437error: 438 ipcomp_free_data(ipcd); 439 mutex_unlock(&ipcomp_resource_mutex); 440 kfree(ipcd); 441 goto out; 442} 443 444static struct xfrm_type ipcomp_type = { 445 .description = "IPCOMP4", 446 .owner = THIS_MODULE, 447 .proto = IPPROTO_COMP, 448 .init_state = ipcomp_init_state, 449 .destructor = ipcomp_destroy, 450 .input = ipcomp_input, 451 .output = ipcomp_output 452}; 453 454static struct net_protocol ipcomp4_protocol = { 455 .handler = xfrm4_rcv, 456 .err_handler = ipcomp4_err, 457 .no_policy = 1, 458}; 459 460static int __init ipcomp4_init(void) 461{ 462 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) { 463 printk(KERN_INFO "ipcomp init: can't add xfrm type\n"); 464 return -EAGAIN; 465 } 466 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) { 467 printk(KERN_INFO "ipcomp init: can't add protocol\n"); 468 xfrm_unregister_type(&ipcomp_type, AF_INET); 469 return -EAGAIN; 470 } 471 return 0; 472} 473 474static void __exit ipcomp4_fini(void) 475{ 476 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) 477 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n"); 478 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0) 479 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n"); 480} 481 482module_init(ipcomp4_init); 483module_exit(ipcomp4_fini); 484 485MODULE_LICENSE("GPL"); 486MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173"); 487MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); 488 489MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP); 490