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