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/pfkeyv2.h> 20 #include <linux/percpu.h> 21 #include <linux/smp.h> 22 #include <linux/list.h> 23 #include <linux/vmalloc.h> 24 #include <linux/rtnetlink.h> 25 #include <linux/mutex.h> 26 #include <net/ip.h> 27 #include <net/xfrm.h> 28 #include <net/icmp.h> 29 #include <net/ipcomp.h> 30 #include <net/protocol.h> 31 32 struct ipcomp_tfms { 33 struct list_head list; 34 struct crypto_comp **tfms; 35 int users; 36 }; 37 38 static DEFINE_MUTEX(ipcomp_resource_mutex); 39 static void **ipcomp_scratches; 40 static int ipcomp_scratch_users; 41 static LIST_HEAD(ipcomp_tfms_list); 42 43 static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb) 44 { 45 struct ipcomp_data *ipcd = x->data; 46 const int plen = skb->len; 47 int dlen = IPCOMP_SCRATCH_SIZE; 48 const u8 *start = skb->data; 49 const int cpu = get_cpu(); 50 u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu); 51 struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu); 52 int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen); 53 54 if (err) 55 goto out; 56 57 if (dlen < (plen + sizeof(struct ip_comp_hdr))) { 58 err = -EINVAL; 59 goto out; 60 } 61 62 err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC); 63 if (err) 64 goto out; 65 66 skb->truesize += dlen - plen; 67 __skb_put(skb, dlen - plen); 68 skb_copy_to_linear_data(skb, scratch, dlen); 69 out: 70 put_cpu(); 71 return err; 72 } 73 74 static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb) 75 { 76 int err = -ENOMEM; 77 struct ip_comp_hdr *ipch; 78 79 if (skb_linearize_cow(skb)) 80 goto out; 81 82 skb->ip_summed = CHECKSUM_NONE; 83 84 /* Remove ipcomp header and decompress original payload */ 85 ipch = (void *)skb->data; 86 skb->transport_header = skb->network_header + sizeof(*ipch); 87 __skb_pull(skb, sizeof(*ipch)); 88 err = ipcomp_decompress(x, skb); 89 if (err) 90 goto out; 91 92 err = ipch->nexthdr; 93 94 out: 95 return err; 96 } 97 98 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb) 99 { 100 struct ipcomp_data *ipcd = x->data; 101 const int plen = skb->len; 102 int dlen = IPCOMP_SCRATCH_SIZE; 103 u8 *start = skb->data; 104 const int cpu = get_cpu(); 105 u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu); 106 struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu); 107 int err = crypto_comp_compress(tfm, start, plen, scratch, &dlen); 108 109 if (err) 110 goto out; 111 112 if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) { 113 err = -EMSGSIZE; 114 goto out; 115 } 116 117 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen); 118 put_cpu(); 119 120 pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr)); 121 return 0; 122 123 out: 124 put_cpu(); 125 return err; 126 } 127 128 static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb) 129 { 130 int err; 131 struct ip_comp_hdr *ipch; 132 struct ipcomp_data *ipcd = x->data; 133 134 if (skb->len < ipcd->threshold) { 135 /* Don't bother compressing */ 136 goto out_ok; 137 } 138 139 if (skb_linearize_cow(skb)) 140 goto out_ok; 141 142 err = ipcomp_compress(x, skb); 143 144 if (err) { 145 goto out_ok; 146 } 147 148 /* Install ipcomp header, convert into ipcomp datagram. */ 149 ipch = ip_comp_hdr(skb); 150 ipch->nexthdr = *skb_mac_header(skb); 151 ipch->flags = 0; 152 ipch->cpi = htons((u16 )ntohl(x->id.spi)); 153 *skb_mac_header(skb) = IPPROTO_COMP; 154 out_ok: 155 skb_push(skb, -skb_network_offset(skb)); 156 return 0; 157 } 158 159 static void ipcomp4_err(struct sk_buff *skb, u32 info) 160 { 161 __be32 spi; 162 struct iphdr *iph = (struct iphdr *)skb->data; 163 struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2)); 164 struct xfrm_state *x; 165 166 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH || 167 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) 168 return; 169 170 spi = htonl(ntohs(ipch->cpi)); 171 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, 172 spi, IPPROTO_COMP, AF_INET); 173 if (!x) 174 return; 175 NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n", 176 spi, NIPQUAD(iph->daddr)); 177 xfrm_state_put(x); 178 } 179 180 /* We always hold one tunnel user reference to indicate a tunnel */ 181 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x) 182 { 183 struct xfrm_state *t; 184 u8 mode = XFRM_MODE_TUNNEL; 185 186 t = xfrm_state_alloc(); 187 if (t == NULL) 188 goto out; 189 190 t->id.proto = IPPROTO_IPIP; 191 t->id.spi = x->props.saddr.a4; 192 t->id.daddr.a4 = x->id.daddr.a4; 193 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 194 t->props.family = AF_INET; 195 if (x->props.mode == XFRM_MODE_BEET) 196 mode = x->props.mode; 197 t->props.mode = mode; 198 t->props.saddr.a4 = x->props.saddr.a4; 199 t->props.flags = x->props.flags; 200 201 if (xfrm_init_state(t)) 202 goto error; 203 204 atomic_set(&t->tunnel_users, 1); 205 out: 206 return t; 207 208 error: 209 t->km.state = XFRM_STATE_DEAD; 210 xfrm_state_put(t); 211 t = NULL; 212 goto out; 213 } 214 215 /* 216 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are 217 * always incremented on success. 218 */ 219 static int ipcomp_tunnel_attach(struct xfrm_state *x) 220 { 221 int err = 0; 222 struct xfrm_state *t; 223 224 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4, 225 x->props.saddr.a4, IPPROTO_IPIP, AF_INET); 226 if (!t) { 227 t = ipcomp_tunnel_create(x); 228 if (!t) { 229 err = -EINVAL; 230 goto out; 231 } 232 xfrm_state_insert(t); 233 xfrm_state_hold(t); 234 } 235 x->tunnel = t; 236 atomic_inc(&t->tunnel_users); 237 out: 238 return err; 239 } 240 241 static void ipcomp_free_scratches(void) 242 { 243 int i; 244 void **scratches; 245 246 if (--ipcomp_scratch_users) 247 return; 248 249 scratches = ipcomp_scratches; 250 if (!scratches) 251 return; 252 253 for_each_possible_cpu(i) 254 vfree(*per_cpu_ptr(scratches, i)); 255 256 free_percpu(scratches); 257 } 258 259 static void **ipcomp_alloc_scratches(void) 260 { 261 int i; 262 void **scratches; 263 264 if (ipcomp_scratch_users++) 265 return ipcomp_scratches; 266 267 scratches = alloc_percpu(void *); 268 if (!scratches) 269 return NULL; 270 271 ipcomp_scratches = scratches; 272 273 for_each_possible_cpu(i) { 274 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); 275 if (!scratch) 276 return NULL; 277 *per_cpu_ptr(scratches, i) = scratch; 278 } 279 280 return scratches; 281 } 282 283 static void ipcomp_free_tfms(struct crypto_comp **tfms) 284 { 285 struct ipcomp_tfms *pos; 286 int cpu; 287 288 list_for_each_entry(pos, &ipcomp_tfms_list, list) { 289 if (pos->tfms == tfms) 290 break; 291 } 292 293 BUG_TRAP(pos); 294 295 if (--pos->users) 296 return; 297 298 list_del(&pos->list); 299 kfree(pos); 300 301 if (!tfms) 302 return; 303 304 for_each_possible_cpu(cpu) { 305 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu); 306 crypto_free_comp(tfm); 307 } 308 free_percpu(tfms); 309 } 310 311 static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name) 312 { 313 struct ipcomp_tfms *pos; 314 struct crypto_comp **tfms; 315 int cpu; 316 317 /* This can be any valid CPU ID so we don't need locking. */ 318 cpu = raw_smp_processor_id(); 319 320 list_for_each_entry(pos, &ipcomp_tfms_list, list) { 321 struct crypto_comp *tfm; 322 323 tfms = pos->tfms; 324 tfm = *per_cpu_ptr(tfms, cpu); 325 326 if (!strcmp(crypto_comp_name(tfm), alg_name)) { 327 pos->users++; 328 return tfms; 329 } 330 } 331 332 pos = kmalloc(sizeof(*pos), GFP_KERNEL); 333 if (!pos) 334 return NULL; 335 336 pos->users = 1; 337 INIT_LIST_HEAD(&pos->list); 338 list_add(&pos->list, &ipcomp_tfms_list); 339 340 pos->tfms = tfms = alloc_percpu(struct crypto_comp *); 341 if (!tfms) 342 goto error; 343 344 for_each_possible_cpu(cpu) { 345 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0, 346 CRYPTO_ALG_ASYNC); 347 if (!tfm) 348 goto error; 349 *per_cpu_ptr(tfms, cpu) = tfm; 350 } 351 352 return tfms; 353 354 error: 355 ipcomp_free_tfms(tfms); 356 return NULL; 357 } 358 359 static void ipcomp_free_data(struct ipcomp_data *ipcd) 360 { 361 if (ipcd->tfms) 362 ipcomp_free_tfms(ipcd->tfms); 363 ipcomp_free_scratches(); 364 } 365 366 static void ipcomp_destroy(struct xfrm_state *x) 367 { 368 struct ipcomp_data *ipcd = x->data; 369 if (!ipcd) 370 return; 371 xfrm_state_delete_tunnel(x); 372 mutex_lock(&ipcomp_resource_mutex); 373 ipcomp_free_data(ipcd); 374 mutex_unlock(&ipcomp_resource_mutex); 375 kfree(ipcd); 376 } 377 378 static int ipcomp_init_state(struct xfrm_state *x) 379 { 380 int err; 381 struct ipcomp_data *ipcd; 382 struct xfrm_algo_desc *calg_desc; 383 384 err = -EINVAL; 385 if (!x->calg) 386 goto out; 387 388 if (x->encap) 389 goto out; 390 391 err = -ENOMEM; 392 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL); 393 if (!ipcd) 394 goto out; 395 396 x->props.header_len = 0; 397 if (x->props.mode == XFRM_MODE_TUNNEL) 398 x->props.header_len += sizeof(struct iphdr); 399 400 mutex_lock(&ipcomp_resource_mutex); 401 if (!ipcomp_alloc_scratches()) 402 goto error; 403 404 ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name); 405 if (!ipcd->tfms) 406 goto error; 407 mutex_unlock(&ipcomp_resource_mutex); 408 409 if (x->props.mode == XFRM_MODE_TUNNEL) { 410 err = ipcomp_tunnel_attach(x); 411 if (err) 412 goto error_tunnel; 413 } 414 415 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0); 416 BUG_ON(!calg_desc); 417 ipcd->threshold = calg_desc->uinfo.comp.threshold; 418 x->data = ipcd; 419 err = 0; 420 out: 421 return err; 422 423 error_tunnel: 424 mutex_lock(&ipcomp_resource_mutex); 425 error: 426 ipcomp_free_data(ipcd); 427 mutex_unlock(&ipcomp_resource_mutex); 428 kfree(ipcd); 429 goto out; 430 } 431 432 static struct xfrm_type ipcomp_type = { 433 .description = "IPCOMP4", 434 .owner = THIS_MODULE, 435 .proto = IPPROTO_COMP, 436 .init_state = ipcomp_init_state, 437 .destructor = ipcomp_destroy, 438 .input = ipcomp_input, 439 .output = ipcomp_output 440 }; 441 442 static struct net_protocol ipcomp4_protocol = { 443 .handler = xfrm4_rcv, 444 .err_handler = ipcomp4_err, 445 .no_policy = 1, 446 }; 447 448 static int __init ipcomp4_init(void) 449 { 450 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) { 451 printk(KERN_INFO "ipcomp init: can't add xfrm type\n"); 452 return -EAGAIN; 453 } 454 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) { 455 printk(KERN_INFO "ipcomp init: can't add protocol\n"); 456 xfrm_unregister_type(&ipcomp_type, AF_INET); 457 return -EAGAIN; 458 } 459 return 0; 460 } 461 462 static void __exit ipcomp4_fini(void) 463 { 464 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) 465 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n"); 466 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0) 467 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n"); 468 } 469 470 module_init(ipcomp4_init); 471 module_exit(ipcomp4_fini); 472 473 MODULE_LICENSE("GPL"); 474 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173"); 475 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); 476 477 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP); 478