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_tfm **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_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_put(skb, dlen - plen); 74 memcpy(skb->data, scratch, dlen); 75 out: 76 put_cpu(); 77 return err; 78 } 79 80 static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb) 81 { 82 int err = -ENOMEM; 83 struct iphdr *iph; 84 struct ip_comp_hdr *ipch; 85 86 if (skb_linearize_cow(skb)) 87 goto out; 88 89 skb->ip_summed = CHECKSUM_NONE; 90 91 /* Remove ipcomp header and decompress original payload */ 92 iph = skb->nh.iph; 93 ipch = (void *)skb->data; 94 iph->protocol = ipch->nexthdr; 95 skb->h.raw = skb->nh.raw + sizeof(*ipch); 96 __skb_pull(skb, sizeof(*ipch)); 97 err = ipcomp_decompress(x, skb); 98 99 out: 100 return err; 101 } 102 103 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb) 104 { 105 int err, plen, dlen, ihlen; 106 struct iphdr *iph = skb->nh.iph; 107 struct ipcomp_data *ipcd = x->data; 108 u8 *start, *scratch; 109 struct crypto_tfm *tfm; 110 int cpu; 111 112 ihlen = iph->ihl * 4; 113 plen = skb->len - ihlen; 114 dlen = IPCOMP_SCRATCH_SIZE; 115 start = skb->data + ihlen; 116 117 cpu = get_cpu(); 118 scratch = *per_cpu_ptr(ipcomp_scratches, cpu); 119 tfm = *per_cpu_ptr(ipcd->tfms, cpu); 120 121 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen); 122 if (err) 123 goto out; 124 125 if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) { 126 err = -EMSGSIZE; 127 goto out; 128 } 129 130 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen); 131 put_cpu(); 132 133 pskb_trim(skb, ihlen + dlen + sizeof(struct ip_comp_hdr)); 134 return 0; 135 136 out: 137 put_cpu(); 138 return err; 139 } 140 141 static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb) 142 { 143 int err; 144 struct iphdr *iph; 145 struct ip_comp_hdr *ipch; 146 struct ipcomp_data *ipcd = x->data; 147 int hdr_len = 0; 148 149 iph = skb->nh.iph; 150 iph->tot_len = htons(skb->len); 151 hdr_len = iph->ihl * 4; 152 if ((skb->len - hdr_len) < ipcd->threshold) { 153 /* Don't bother compressing */ 154 goto out_ok; 155 } 156 157 if (skb_linearize_cow(skb)) 158 goto out_ok; 159 160 err = ipcomp_compress(x, skb); 161 iph = skb->nh.iph; 162 163 if (err) { 164 goto out_ok; 165 } 166 167 /* Install ipcomp header, convert into ipcomp datagram. */ 168 iph->tot_len = htons(skb->len); 169 ipch = (struct ip_comp_hdr *)((char *)iph + iph->ihl * 4); 170 ipch->nexthdr = iph->protocol; 171 ipch->flags = 0; 172 ipch->cpi = htons((u16 )ntohl(x->id.spi)); 173 iph->protocol = IPPROTO_COMP; 174 ip_send_check(iph); 175 return 0; 176 177 out_ok: 178 if (x->props.mode) 179 ip_send_check(iph); 180 return 0; 181 } 182 183 static void ipcomp4_err(struct sk_buff *skb, u32 info) 184 { 185 u32 spi; 186 struct iphdr *iph = (struct iphdr *)skb->data; 187 struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2)); 188 struct xfrm_state *x; 189 190 if (skb->h.icmph->type != ICMP_DEST_UNREACH || 191 skb->h.icmph->code != ICMP_FRAG_NEEDED) 192 return; 193 194 spi = htonl(ntohs(ipch->cpi)); 195 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, 196 spi, IPPROTO_COMP, AF_INET); 197 if (!x) 198 return; 199 NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n", 200 spi, NIPQUAD(iph->daddr)); 201 xfrm_state_put(x); 202 } 203 204 /* We always hold one tunnel user reference to indicate a tunnel */ 205 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x) 206 { 207 struct xfrm_state *t; 208 209 t = xfrm_state_alloc(); 210 if (t == NULL) 211 goto out; 212 213 t->id.proto = IPPROTO_IPIP; 214 t->id.spi = x->props.saddr.a4; 215 t->id.daddr.a4 = x->id.daddr.a4; 216 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 217 t->props.family = AF_INET; 218 t->props.mode = 1; 219 t->props.saddr.a4 = x->props.saddr.a4; 220 t->props.flags = x->props.flags; 221 222 if (xfrm_init_state(t)) 223 goto error; 224 225 atomic_set(&t->tunnel_users, 1); 226 out: 227 return t; 228 229 error: 230 t->km.state = XFRM_STATE_DEAD; 231 xfrm_state_put(t); 232 t = NULL; 233 goto out; 234 } 235 236 /* 237 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are 238 * always incremented on success. 239 */ 240 static int ipcomp_tunnel_attach(struct xfrm_state *x) 241 { 242 int err = 0; 243 struct xfrm_state *t; 244 245 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4, 246 x->props.saddr.a4, IPPROTO_IPIP, AF_INET); 247 if (!t) { 248 t = ipcomp_tunnel_create(x); 249 if (!t) { 250 err = -EINVAL; 251 goto out; 252 } 253 xfrm_state_insert(t); 254 xfrm_state_hold(t); 255 } 256 x->tunnel = t; 257 atomic_inc(&t->tunnel_users); 258 out: 259 return err; 260 } 261 262 static void ipcomp_free_scratches(void) 263 { 264 int i; 265 void **scratches; 266 267 if (--ipcomp_scratch_users) 268 return; 269 270 scratches = ipcomp_scratches; 271 if (!scratches) 272 return; 273 274 for_each_possible_cpu(i) 275 vfree(*per_cpu_ptr(scratches, i)); 276 277 free_percpu(scratches); 278 } 279 280 static void **ipcomp_alloc_scratches(void) 281 { 282 int i; 283 void **scratches; 284 285 if (ipcomp_scratch_users++) 286 return ipcomp_scratches; 287 288 scratches = alloc_percpu(void *); 289 if (!scratches) 290 return NULL; 291 292 ipcomp_scratches = scratches; 293 294 for_each_possible_cpu(i) { 295 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); 296 if (!scratch) 297 return NULL; 298 *per_cpu_ptr(scratches, i) = scratch; 299 } 300 301 return scratches; 302 } 303 304 static void ipcomp_free_tfms(struct crypto_tfm **tfms) 305 { 306 struct ipcomp_tfms *pos; 307 int cpu; 308 309 list_for_each_entry(pos, &ipcomp_tfms_list, list) { 310 if (pos->tfms == tfms) 311 break; 312 } 313 314 BUG_TRAP(pos); 315 316 if (--pos->users) 317 return; 318 319 list_del(&pos->list); 320 kfree(pos); 321 322 if (!tfms) 323 return; 324 325 for_each_possible_cpu(cpu) { 326 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu); 327 crypto_free_tfm(tfm); 328 } 329 free_percpu(tfms); 330 } 331 332 static struct crypto_tfm **ipcomp_alloc_tfms(const char *alg_name) 333 { 334 struct ipcomp_tfms *pos; 335 struct crypto_tfm **tfms; 336 int cpu; 337 338 /* This can be any valid CPU ID so we don't need locking. */ 339 cpu = raw_smp_processor_id(); 340 341 list_for_each_entry(pos, &ipcomp_tfms_list, list) { 342 struct crypto_tfm *tfm; 343 344 tfms = pos->tfms; 345 tfm = *per_cpu_ptr(tfms, cpu); 346 347 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) { 348 pos->users++; 349 return tfms; 350 } 351 } 352 353 pos = kmalloc(sizeof(*pos), GFP_KERNEL); 354 if (!pos) 355 return NULL; 356 357 pos->users = 1; 358 INIT_LIST_HEAD(&pos->list); 359 list_add(&pos->list, &ipcomp_tfms_list); 360 361 pos->tfms = tfms = alloc_percpu(struct crypto_tfm *); 362 if (!tfms) 363 goto error; 364 365 for_each_possible_cpu(cpu) { 366 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0); 367 if (!tfm) 368 goto error; 369 *per_cpu_ptr(tfms, cpu) = tfm; 370 } 371 372 return tfms; 373 374 error: 375 ipcomp_free_tfms(tfms); 376 return NULL; 377 } 378 379 static void ipcomp_free_data(struct ipcomp_data *ipcd) 380 { 381 if (ipcd->tfms) 382 ipcomp_free_tfms(ipcd->tfms); 383 ipcomp_free_scratches(); 384 } 385 386 static void ipcomp_destroy(struct xfrm_state *x) 387 { 388 struct ipcomp_data *ipcd = x->data; 389 if (!ipcd) 390 return; 391 xfrm_state_delete_tunnel(x); 392 mutex_lock(&ipcomp_resource_mutex); 393 ipcomp_free_data(ipcd); 394 mutex_unlock(&ipcomp_resource_mutex); 395 kfree(ipcd); 396 } 397 398 static int ipcomp_init_state(struct xfrm_state *x) 399 { 400 int err; 401 struct ipcomp_data *ipcd; 402 struct xfrm_algo_desc *calg_desc; 403 404 err = -EINVAL; 405 if (!x->calg) 406 goto out; 407 408 if (x->encap) 409 goto out; 410 411 err = -ENOMEM; 412 ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL); 413 if (!ipcd) 414 goto out; 415 416 memset(ipcd, 0, sizeof(*ipcd)); 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; 441 out: 442 return err; 443 444 error_tunnel: 445 mutex_lock(&ipcomp_resource_mutex); 446 error: 447 ipcomp_free_data(ipcd); 448 mutex_unlock(&ipcomp_resource_mutex); 449 kfree(ipcd); 450 goto out; 451 } 452 453 static 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 }; 462 463 static struct net_protocol ipcomp4_protocol = { 464 .handler = xfrm4_rcv, 465 .err_handler = ipcomp4_err, 466 .no_policy = 1, 467 }; 468 469 static 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 } 482 483 static 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 } 490 491 module_init(ipcomp4_init); 492 module_exit(ipcomp4_fini); 493 494 MODULE_LICENSE("GPL"); 495 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173"); 496 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); 497 498