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/semaphore.h> 18 #include <linux/crypto.h> 19 #include <linux/err.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 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); 70 out: 71 put_cpu(); 72 return err; 73 } 74 75 static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb) 76 { 77 int nexthdr; 78 int err = -ENOMEM; 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 ipch = (void *)skb->data; 88 nexthdr = ipch->nexthdr; 89 90 skb->transport_header = skb->network_header + sizeof(*ipch); 91 __skb_pull(skb, sizeof(*ipch)); 92 err = ipcomp_decompress(x, skb); 93 if (err) 94 goto out; 95 96 err = nexthdr; 97 98 out: 99 return err; 100 } 101 102 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb) 103 { 104 struct ipcomp_data *ipcd = x->data; 105 const int plen = skb->len; 106 int dlen = IPCOMP_SCRATCH_SIZE; 107 u8 *start = skb->data; 108 const int cpu = get_cpu(); 109 u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu); 110 struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu); 111 int err = crypto_comp_compress(tfm, start, plen, scratch, &dlen); 112 113 if (err) 114 goto out; 115 116 if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) { 117 err = -EMSGSIZE; 118 goto out; 119 } 120 121 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen); 122 put_cpu(); 123 124 pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr)); 125 return 0; 126 127 out: 128 put_cpu(); 129 return err; 130 } 131 132 static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb) 133 { 134 int err; 135 struct ip_comp_hdr *ipch; 136 struct ipcomp_data *ipcd = x->data; 137 138 if (skb->len < ipcd->threshold) { 139 /* Don't bother compressing */ 140 goto out_ok; 141 } 142 143 if (skb_linearize_cow(skb)) 144 goto out_ok; 145 146 err = ipcomp_compress(x, skb); 147 148 if (err) { 149 goto out_ok; 150 } 151 152 /* Install ipcomp header, convert into ipcomp datagram. */ 153 ipch = ip_comp_hdr(skb); 154 ipch->nexthdr = *skb_mac_header(skb); 155 ipch->flags = 0; 156 ipch->cpi = htons((u16 )ntohl(x->id.spi)); 157 *skb_mac_header(skb) = IPPROTO_COMP; 158 out_ok: 159 skb_push(skb, -skb_network_offset(skb)); 160 return 0; 161 } 162 163 static void ipcomp4_err(struct sk_buff *skb, u32 info) 164 { 165 __be32 spi; 166 struct iphdr *iph = (struct iphdr *)skb->data; 167 struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2)); 168 struct xfrm_state *x; 169 170 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH || 171 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) 172 return; 173 174 spi = htonl(ntohs(ipch->cpi)); 175 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, 176 spi, IPPROTO_COMP, AF_INET); 177 if (!x) 178 return; 179 NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n", 180 spi, NIPQUAD(iph->daddr)); 181 xfrm_state_put(x); 182 } 183 184 /* We always hold one tunnel user reference to indicate a tunnel */ 185 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x) 186 { 187 struct xfrm_state *t; 188 189 t = xfrm_state_alloc(); 190 if (t == NULL) 191 goto out; 192 193 t->id.proto = IPPROTO_IPIP; 194 t->id.spi = x->props.saddr.a4; 195 t->id.daddr.a4 = x->id.daddr.a4; 196 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 197 t->props.family = AF_INET; 198 t->props.mode = x->props.mode; 199 t->props.saddr.a4 = x->props.saddr.a4; 200 t->props.flags = x->props.flags; 201 202 if (xfrm_init_state(t)) 203 goto error; 204 205 atomic_set(&t->tunnel_users, 1); 206 out: 207 return t; 208 209 error: 210 t->km.state = XFRM_STATE_DEAD; 211 xfrm_state_put(t); 212 t = NULL; 213 goto out; 214 } 215 216 /* 217 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are 218 * always incremented on success. 219 */ 220 static int ipcomp_tunnel_attach(struct xfrm_state *x) 221 { 222 int err = 0; 223 struct xfrm_state *t; 224 225 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4, 226 x->props.saddr.a4, IPPROTO_IPIP, AF_INET); 227 if (!t) { 228 t = ipcomp_tunnel_create(x); 229 if (!t) { 230 err = -EINVAL; 231 goto out; 232 } 233 xfrm_state_insert(t); 234 xfrm_state_hold(t); 235 } 236 x->tunnel = t; 237 atomic_inc(&t->tunnel_users); 238 out: 239 return err; 240 } 241 242 static void ipcomp_free_scratches(void) 243 { 244 int i; 245 void **scratches; 246 247 if (--ipcomp_scratch_users) 248 return; 249 250 scratches = ipcomp_scratches; 251 if (!scratches) 252 return; 253 254 for_each_possible_cpu(i) 255 vfree(*per_cpu_ptr(scratches, i)); 256 257 free_percpu(scratches); 258 } 259 260 static void **ipcomp_alloc_scratches(void) 261 { 262 int i; 263 void **scratches; 264 265 if (ipcomp_scratch_users++) 266 return ipcomp_scratches; 267 268 scratches = alloc_percpu(void *); 269 if (!scratches) 270 return NULL; 271 272 ipcomp_scratches = scratches; 273 274 for_each_possible_cpu(i) { 275 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); 276 if (!scratch) 277 return NULL; 278 *per_cpu_ptr(scratches, i) = scratch; 279 } 280 281 return scratches; 282 } 283 284 static void ipcomp_free_tfms(struct crypto_comp **tfms) 285 { 286 struct ipcomp_tfms *pos; 287 int cpu; 288 289 list_for_each_entry(pos, &ipcomp_tfms_list, list) { 290 if (pos->tfms == tfms) 291 break; 292 } 293 294 BUG_TRAP(pos); 295 296 if (--pos->users) 297 return; 298 299 list_del(&pos->list); 300 kfree(pos); 301 302 if (!tfms) 303 return; 304 305 for_each_possible_cpu(cpu) { 306 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu); 307 crypto_free_comp(tfm); 308 } 309 free_percpu(tfms); 310 } 311 312 static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name) 313 { 314 struct ipcomp_tfms *pos; 315 struct crypto_comp **tfms; 316 int cpu; 317 318 /* This can be any valid CPU ID so we don't need locking. */ 319 cpu = raw_smp_processor_id(); 320 321 list_for_each_entry(pos, &ipcomp_tfms_list, list) { 322 struct crypto_comp *tfm; 323 324 tfms = pos->tfms; 325 tfm = *per_cpu_ptr(tfms, cpu); 326 327 if (!strcmp(crypto_comp_name(tfm), alg_name)) { 328 pos->users++; 329 return tfms; 330 } 331 } 332 333 pos = kmalloc(sizeof(*pos), GFP_KERNEL); 334 if (!pos) 335 return NULL; 336 337 pos->users = 1; 338 INIT_LIST_HEAD(&pos->list); 339 list_add(&pos->list, &ipcomp_tfms_list); 340 341 pos->tfms = tfms = alloc_percpu(struct crypto_comp *); 342 if (!tfms) 343 goto error; 344 345 for_each_possible_cpu(cpu) { 346 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0, 347 CRYPTO_ALG_ASYNC); 348 if (IS_ERR(tfm)) 349 goto error; 350 *per_cpu_ptr(tfms, cpu) = tfm; 351 } 352 353 return tfms; 354 355 error: 356 ipcomp_free_tfms(tfms); 357 return NULL; 358 } 359 360 static void ipcomp_free_data(struct ipcomp_data *ipcd) 361 { 362 if (ipcd->tfms) 363 ipcomp_free_tfms(ipcd->tfms); 364 ipcomp_free_scratches(); 365 } 366 367 static void ipcomp_destroy(struct xfrm_state *x) 368 { 369 struct ipcomp_data *ipcd = x->data; 370 if (!ipcd) 371 return; 372 xfrm_state_delete_tunnel(x); 373 mutex_lock(&ipcomp_resource_mutex); 374 ipcomp_free_data(ipcd); 375 mutex_unlock(&ipcomp_resource_mutex); 376 kfree(ipcd); 377 } 378 379 static int ipcomp_init_state(struct xfrm_state *x) 380 { 381 int err; 382 struct ipcomp_data *ipcd; 383 struct xfrm_algo_desc *calg_desc; 384 385 err = -EINVAL; 386 if (!x->calg) 387 goto out; 388 389 if (x->encap) 390 goto out; 391 392 x->props.header_len = 0; 393 switch (x->props.mode) { 394 case XFRM_MODE_TRANSPORT: 395 break; 396 case XFRM_MODE_TUNNEL: 397 x->props.header_len += sizeof(struct iphdr); 398 break; 399 default: 400 goto out; 401 } 402 403 err = -ENOMEM; 404 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL); 405 if (!ipcd) 406 goto out; 407 408 mutex_lock(&ipcomp_resource_mutex); 409 if (!ipcomp_alloc_scratches()) 410 goto error; 411 412 ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name); 413 if (!ipcd->tfms) 414 goto error; 415 mutex_unlock(&ipcomp_resource_mutex); 416 417 if (x->props.mode == XFRM_MODE_TUNNEL) { 418 err = ipcomp_tunnel_attach(x); 419 if (err) 420 goto error_tunnel; 421 } 422 423 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0); 424 BUG_ON(!calg_desc); 425 ipcd->threshold = calg_desc->uinfo.comp.threshold; 426 x->data = ipcd; 427 err = 0; 428 out: 429 return err; 430 431 error_tunnel: 432 mutex_lock(&ipcomp_resource_mutex); 433 error: 434 ipcomp_free_data(ipcd); 435 mutex_unlock(&ipcomp_resource_mutex); 436 kfree(ipcd); 437 goto out; 438 } 439 440 static const struct xfrm_type ipcomp_type = { 441 .description = "IPCOMP4", 442 .owner = THIS_MODULE, 443 .proto = IPPROTO_COMP, 444 .init_state = ipcomp_init_state, 445 .destructor = ipcomp_destroy, 446 .input = ipcomp_input, 447 .output = ipcomp_output 448 }; 449 450 static struct net_protocol ipcomp4_protocol = { 451 .handler = xfrm4_rcv, 452 .err_handler = ipcomp4_err, 453 .no_policy = 1, 454 }; 455 456 static int __init ipcomp4_init(void) 457 { 458 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) { 459 printk(KERN_INFO "ipcomp init: can't add xfrm type\n"); 460 return -EAGAIN; 461 } 462 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) { 463 printk(KERN_INFO "ipcomp init: can't add protocol\n"); 464 xfrm_unregister_type(&ipcomp_type, AF_INET); 465 return -EAGAIN; 466 } 467 return 0; 468 } 469 470 static void __exit ipcomp4_fini(void) 471 { 472 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) 473 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n"); 474 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0) 475 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n"); 476 } 477 478 module_init(ipcomp4_init); 479 module_exit(ipcomp4_fini); 480 481 MODULE_LICENSE("GPL"); 482 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173"); 483 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); 484 485 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP); 486