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 33 struct ipcomp_tfms { 34 struct list_head list; 35 struct crypto_comp **tfms; 36 int users; 37 }; 38 39 static DEFINE_MUTEX(ipcomp_resource_mutex); 40 static void **ipcomp_scratches; 41 static int ipcomp_scratch_users; 42 static LIST_HEAD(ipcomp_tfms_list); 43 44 static 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_comp *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); 76 out: 77 put_cpu(); 78 return err; 79 } 80 81 static 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); 99 100 out: 101 return err; 102 } 103 104 static 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_comp *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; 136 137 out: 138 put_cpu(); 139 return err; 140 } 141 142 static 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; 177 178 out_ok: 179 if (x->props.mode == XFRM_MODE_TUNNEL) 180 ip_send_check(iph); 181 return 0; 182 } 183 184 static void ipcomp4_err(struct sk_buff *skb, u32 info) 185 { 186 __be32 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 */ 206 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x) 207 { 208 struct xfrm_state *t; 209 u8 mode = XFRM_MODE_TUNNEL; 210 211 t = xfrm_state_alloc(); 212 if (t == NULL) 213 goto out; 214 215 t->id.proto = IPPROTO_IPIP; 216 t->id.spi = x->props.saddr.a4; 217 t->id.daddr.a4 = x->id.daddr.a4; 218 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 219 t->props.family = AF_INET; 220 if (x->props.mode == XFRM_MODE_BEET) 221 mode = x->props.mode; 222 t->props.mode = mode; 223 t->props.saddr.a4 = x->props.saddr.a4; 224 t->props.flags = x->props.flags; 225 226 if (xfrm_init_state(t)) 227 goto error; 228 229 atomic_set(&t->tunnel_users, 1); 230 out: 231 return t; 232 233 error: 234 t->km.state = XFRM_STATE_DEAD; 235 xfrm_state_put(t); 236 t = NULL; 237 goto out; 238 } 239 240 /* 241 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are 242 * always incremented on success. 243 */ 244 static int ipcomp_tunnel_attach(struct xfrm_state *x) 245 { 246 int err = 0; 247 struct xfrm_state *t; 248 249 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4, 250 x->props.saddr.a4, IPPROTO_IPIP, AF_INET); 251 if (!t) { 252 t = ipcomp_tunnel_create(x); 253 if (!t) { 254 err = -EINVAL; 255 goto out; 256 } 257 xfrm_state_insert(t); 258 xfrm_state_hold(t); 259 } 260 x->tunnel = t; 261 atomic_inc(&t->tunnel_users); 262 out: 263 return err; 264 } 265 266 static void ipcomp_free_scratches(void) 267 { 268 int i; 269 void **scratches; 270 271 if (--ipcomp_scratch_users) 272 return; 273 274 scratches = ipcomp_scratches; 275 if (!scratches) 276 return; 277 278 for_each_possible_cpu(i) 279 vfree(*per_cpu_ptr(scratches, i)); 280 281 free_percpu(scratches); 282 } 283 284 static void **ipcomp_alloc_scratches(void) 285 { 286 int i; 287 void **scratches; 288 289 if (ipcomp_scratch_users++) 290 return ipcomp_scratches; 291 292 scratches = alloc_percpu(void *); 293 if (!scratches) 294 return NULL; 295 296 ipcomp_scratches = scratches; 297 298 for_each_possible_cpu(i) { 299 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); 300 if (!scratch) 301 return NULL; 302 *per_cpu_ptr(scratches, i) = scratch; 303 } 304 305 return scratches; 306 } 307 308 static void ipcomp_free_tfms(struct crypto_comp **tfms) 309 { 310 struct ipcomp_tfms *pos; 311 int cpu; 312 313 list_for_each_entry(pos, &ipcomp_tfms_list, list) { 314 if (pos->tfms == tfms) 315 break; 316 } 317 318 BUG_TRAP(pos); 319 320 if (--pos->users) 321 return; 322 323 list_del(&pos->list); 324 kfree(pos); 325 326 if (!tfms) 327 return; 328 329 for_each_possible_cpu(cpu) { 330 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu); 331 crypto_free_comp(tfm); 332 } 333 free_percpu(tfms); 334 } 335 336 static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name) 337 { 338 struct ipcomp_tfms *pos; 339 struct crypto_comp **tfms; 340 int cpu; 341 342 /* This can be any valid CPU ID so we don't need locking. */ 343 cpu = raw_smp_processor_id(); 344 345 list_for_each_entry(pos, &ipcomp_tfms_list, list) { 346 struct crypto_comp *tfm; 347 348 tfms = pos->tfms; 349 tfm = *per_cpu_ptr(tfms, cpu); 350 351 if (!strcmp(crypto_comp_name(tfm), alg_name)) { 352 pos->users++; 353 return tfms; 354 } 355 } 356 357 pos = kmalloc(sizeof(*pos), GFP_KERNEL); 358 if (!pos) 359 return NULL; 360 361 pos->users = 1; 362 INIT_LIST_HEAD(&pos->list); 363 list_add(&pos->list, &ipcomp_tfms_list); 364 365 pos->tfms = tfms = alloc_percpu(struct crypto_comp *); 366 if (!tfms) 367 goto error; 368 369 for_each_possible_cpu(cpu) { 370 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0, 371 CRYPTO_ALG_ASYNC); 372 if (!tfm) 373 goto error; 374 *per_cpu_ptr(tfms, cpu) = tfm; 375 } 376 377 return tfms; 378 379 error: 380 ipcomp_free_tfms(tfms); 381 return NULL; 382 } 383 384 static void ipcomp_free_data(struct ipcomp_data *ipcd) 385 { 386 if (ipcd->tfms) 387 ipcomp_free_tfms(ipcd->tfms); 388 ipcomp_free_scratches(); 389 } 390 391 static void ipcomp_destroy(struct xfrm_state *x) 392 { 393 struct ipcomp_data *ipcd = x->data; 394 if (!ipcd) 395 return; 396 xfrm_state_delete_tunnel(x); 397 mutex_lock(&ipcomp_resource_mutex); 398 ipcomp_free_data(ipcd); 399 mutex_unlock(&ipcomp_resource_mutex); 400 kfree(ipcd); 401 } 402 403 static int ipcomp_init_state(struct xfrm_state *x) 404 { 405 int err; 406 struct ipcomp_data *ipcd; 407 struct xfrm_algo_desc *calg_desc; 408 409 err = -EINVAL; 410 if (!x->calg) 411 goto out; 412 413 if (x->encap) 414 goto out; 415 416 err = -ENOMEM; 417 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL); 418 if (!ipcd) 419 goto out; 420 421 x->props.header_len = 0; 422 if (x->props.mode == XFRM_MODE_TUNNEL) 423 x->props.header_len += sizeof(struct iphdr); 424 425 mutex_lock(&ipcomp_resource_mutex); 426 if (!ipcomp_alloc_scratches()) 427 goto error; 428 429 ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name); 430 if (!ipcd->tfms) 431 goto error; 432 mutex_unlock(&ipcomp_resource_mutex); 433 434 if (x->props.mode == XFRM_MODE_TUNNEL) { 435 err = ipcomp_tunnel_attach(x); 436 if (err) 437 goto error_tunnel; 438 } 439 440 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0); 441 BUG_ON(!calg_desc); 442 ipcd->threshold = calg_desc->uinfo.comp.threshold; 443 x->data = ipcd; 444 err = 0; 445 out: 446 return err; 447 448 error_tunnel: 449 mutex_lock(&ipcomp_resource_mutex); 450 error: 451 ipcomp_free_data(ipcd); 452 mutex_unlock(&ipcomp_resource_mutex); 453 kfree(ipcd); 454 goto out; 455 } 456 457 static struct xfrm_type ipcomp_type = { 458 .description = "IPCOMP4", 459 .owner = THIS_MODULE, 460 .proto = IPPROTO_COMP, 461 .init_state = ipcomp_init_state, 462 .destructor = ipcomp_destroy, 463 .input = ipcomp_input, 464 .output = ipcomp_output 465 }; 466 467 static struct net_protocol ipcomp4_protocol = { 468 .handler = xfrm4_rcv, 469 .err_handler = ipcomp4_err, 470 .no_policy = 1, 471 }; 472 473 static int __init ipcomp4_init(void) 474 { 475 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) { 476 printk(KERN_INFO "ipcomp init: can't add xfrm type\n"); 477 return -EAGAIN; 478 } 479 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) { 480 printk(KERN_INFO "ipcomp init: can't add protocol\n"); 481 xfrm_unregister_type(&ipcomp_type, AF_INET); 482 return -EAGAIN; 483 } 484 return 0; 485 } 486 487 static void __exit ipcomp4_fini(void) 488 { 489 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) 490 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n"); 491 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0) 492 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n"); 493 } 494 495 module_init(ipcomp4_init); 496 module_exit(ipcomp4_fini); 497 498 MODULE_LICENSE("GPL"); 499 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173"); 500 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); 501 502