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/config.h> 17 #include <linux/module.h> 18 #include <asm/scatterlist.h> 19 #include <asm/semaphore.h> 20 #include <linux/crypto.h> 21 #include <linux/pfkeyv2.h> 22 #include <linux/percpu.h> 23 #include <linux/smp.h> 24 #include <linux/list.h> 25 #include <linux/vmalloc.h> 26 #include <linux/rtnetlink.h> 27 #include <net/ip.h> 28 #include <net/xfrm.h> 29 #include <net/icmp.h> 30 #include <net/ipcomp.h> 31 32 struct ipcomp_tfms { 33 struct list_head list; 34 struct crypto_tfm **tfms; 35 int users; 36 }; 37 38 static DECLARE_MUTEX(ipcomp_resource_sem); 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 int err, plen, dlen; 46 struct iphdr *iph; 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 iph = skb->nh.iph; 76 iph->tot_len = htons(dlen + iph->ihl * 4); 77 out: 78 put_cpu(); 79 return err; 80 } 81 82 static int ipcomp_input(struct xfrm_state *x, 83 struct xfrm_decap_state *decap, struct sk_buff *skb) 84 { 85 u8 nexthdr; 86 int err = 0; 87 struct iphdr *iph; 88 union { 89 struct iphdr iph; 90 char buf[60]; 91 } tmp_iph; 92 93 94 if ((skb_is_nonlinear(skb) || skb_cloned(skb)) && 95 skb_linearize(skb, GFP_ATOMIC) != 0) { 96 err = -ENOMEM; 97 goto out; 98 } 99 100 skb->ip_summed = CHECKSUM_NONE; 101 102 /* Remove ipcomp header and decompress original payload */ 103 iph = skb->nh.iph; 104 memcpy(&tmp_iph, iph, iph->ihl * 4); 105 nexthdr = *(u8 *)skb->data; 106 skb_pull(skb, sizeof(struct ip_comp_hdr)); 107 skb->nh.raw += sizeof(struct ip_comp_hdr); 108 memcpy(skb->nh.raw, &tmp_iph, tmp_iph.iph.ihl * 4); 109 iph = skb->nh.iph; 110 iph->tot_len = htons(ntohs(iph->tot_len) - sizeof(struct ip_comp_hdr)); 111 iph->protocol = nexthdr; 112 skb->h.raw = skb->data; 113 err = ipcomp_decompress(x, skb); 114 115 out: 116 return err; 117 } 118 119 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb) 120 { 121 int err, plen, dlen, ihlen; 122 struct iphdr *iph = skb->nh.iph; 123 struct ipcomp_data *ipcd = x->data; 124 u8 *start, *scratch; 125 struct crypto_tfm *tfm; 126 int cpu; 127 128 ihlen = iph->ihl * 4; 129 plen = skb->len - ihlen; 130 dlen = IPCOMP_SCRATCH_SIZE; 131 start = skb->data + ihlen; 132 133 cpu = get_cpu(); 134 scratch = *per_cpu_ptr(ipcomp_scratches, cpu); 135 tfm = *per_cpu_ptr(ipcd->tfms, cpu); 136 137 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen); 138 if (err) 139 goto out; 140 141 if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) { 142 err = -EMSGSIZE; 143 goto out; 144 } 145 146 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen); 147 put_cpu(); 148 149 pskb_trim(skb, ihlen + dlen + sizeof(struct ip_comp_hdr)); 150 return 0; 151 152 out: 153 put_cpu(); 154 return err; 155 } 156 157 static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb) 158 { 159 int err; 160 struct iphdr *iph; 161 struct ip_comp_hdr *ipch; 162 struct ipcomp_data *ipcd = x->data; 163 int hdr_len = 0; 164 165 iph = skb->nh.iph; 166 iph->tot_len = htons(skb->len); 167 hdr_len = iph->ihl * 4; 168 if ((skb->len - hdr_len) < ipcd->threshold) { 169 /* Don't bother compressing */ 170 goto out_ok; 171 } 172 173 if ((skb_is_nonlinear(skb) || skb_cloned(skb)) && 174 skb_linearize(skb, GFP_ATOMIC) != 0) { 175 goto out_ok; 176 } 177 178 err = ipcomp_compress(x, skb); 179 iph = skb->nh.iph; 180 181 if (err) { 182 goto out_ok; 183 } 184 185 /* Install ipcomp header, convert into ipcomp datagram. */ 186 iph->tot_len = htons(skb->len); 187 ipch = (struct ip_comp_hdr *)((char *)iph + iph->ihl * 4); 188 ipch->nexthdr = iph->protocol; 189 ipch->flags = 0; 190 ipch->cpi = htons((u16 )ntohl(x->id.spi)); 191 iph->protocol = IPPROTO_COMP; 192 ip_send_check(iph); 193 return 0; 194 195 out_ok: 196 if (x->props.mode) 197 ip_send_check(iph); 198 return 0; 199 } 200 201 static void ipcomp4_err(struct sk_buff *skb, u32 info) 202 { 203 u32 spi; 204 struct iphdr *iph = (struct iphdr *)skb->data; 205 struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2)); 206 struct xfrm_state *x; 207 208 if (skb->h.icmph->type != ICMP_DEST_UNREACH || 209 skb->h.icmph->code != ICMP_FRAG_NEEDED) 210 return; 211 212 spi = ntohl(ntohs(ipch->cpi)); 213 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, 214 spi, IPPROTO_COMP, AF_INET); 215 if (!x) 216 return; 217 NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n", 218 spi, NIPQUAD(iph->daddr)); 219 xfrm_state_put(x); 220 } 221 222 /* We always hold one tunnel user reference to indicate a tunnel */ 223 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x) 224 { 225 struct xfrm_state *t; 226 227 t = xfrm_state_alloc(); 228 if (t == NULL) 229 goto out; 230 231 t->id.proto = IPPROTO_IPIP; 232 t->id.spi = x->props.saddr.a4; 233 t->id.daddr.a4 = x->id.daddr.a4; 234 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 235 t->props.family = AF_INET; 236 t->props.mode = 1; 237 t->props.saddr.a4 = x->props.saddr.a4; 238 t->props.flags = x->props.flags; 239 240 if (xfrm_init_state(t)) 241 goto error; 242 243 atomic_set(&t->tunnel_users, 1); 244 out: 245 return t; 246 247 error: 248 t->km.state = XFRM_STATE_DEAD; 249 xfrm_state_put(t); 250 t = NULL; 251 goto out; 252 } 253 254 /* 255 * Must be protected by xfrm_cfg_sem. State and tunnel user references are 256 * always incremented on success. 257 */ 258 static int ipcomp_tunnel_attach(struct xfrm_state *x) 259 { 260 int err = 0; 261 struct xfrm_state *t; 262 263 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4, 264 x->props.saddr.a4, IPPROTO_IPIP, AF_INET); 265 if (!t) { 266 t = ipcomp_tunnel_create(x); 267 if (!t) { 268 err = -EINVAL; 269 goto out; 270 } 271 xfrm_state_insert(t); 272 xfrm_state_hold(t); 273 } 274 x->tunnel = t; 275 atomic_inc(&t->tunnel_users); 276 out: 277 return err; 278 } 279 280 static void ipcomp_free_scratches(void) 281 { 282 int i; 283 void **scratches; 284 285 if (--ipcomp_scratch_users) 286 return; 287 288 scratches = ipcomp_scratches; 289 if (!scratches) 290 return; 291 292 for_each_cpu(i) { 293 void *scratch = *per_cpu_ptr(scratches, i); 294 if (scratch) 295 vfree(scratch); 296 } 297 298 free_percpu(scratches); 299 } 300 301 static void **ipcomp_alloc_scratches(void) 302 { 303 int i; 304 void **scratches; 305 306 if (ipcomp_scratch_users++) 307 return ipcomp_scratches; 308 309 scratches = alloc_percpu(void *); 310 if (!scratches) 311 return NULL; 312 313 ipcomp_scratches = scratches; 314 315 for_each_cpu(i) { 316 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); 317 if (!scratch) 318 return NULL; 319 *per_cpu_ptr(scratches, i) = scratch; 320 } 321 322 return scratches; 323 } 324 325 static void ipcomp_free_tfms(struct crypto_tfm **tfms) 326 { 327 struct ipcomp_tfms *pos; 328 int cpu; 329 330 list_for_each_entry(pos, &ipcomp_tfms_list, list) { 331 if (pos->tfms == tfms) 332 break; 333 } 334 335 BUG_TRAP(pos); 336 337 if (--pos->users) 338 return; 339 340 list_del(&pos->list); 341 kfree(pos); 342 343 if (!tfms) 344 return; 345 346 for_each_cpu(cpu) { 347 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu); 348 if (tfm) 349 crypto_free_tfm(tfm); 350 } 351 free_percpu(tfms); 352 } 353 354 static struct crypto_tfm **ipcomp_alloc_tfms(const char *alg_name) 355 { 356 struct ipcomp_tfms *pos; 357 struct crypto_tfm **tfms; 358 int cpu; 359 360 /* This can be any valid CPU ID so we don't need locking. */ 361 cpu = raw_smp_processor_id(); 362 363 list_for_each_entry(pos, &ipcomp_tfms_list, list) { 364 struct crypto_tfm *tfm; 365 366 tfms = pos->tfms; 367 tfm = *per_cpu_ptr(tfms, cpu); 368 369 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) { 370 pos->users++; 371 return tfms; 372 } 373 } 374 375 pos = kmalloc(sizeof(*pos), GFP_KERNEL); 376 if (!pos) 377 return NULL; 378 379 pos->users = 1; 380 INIT_LIST_HEAD(&pos->list); 381 list_add(&pos->list, &ipcomp_tfms_list); 382 383 pos->tfms = tfms = alloc_percpu(struct crypto_tfm *); 384 if (!tfms) 385 goto error; 386 387 for_each_cpu(cpu) { 388 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0); 389 if (!tfm) 390 goto error; 391 *per_cpu_ptr(tfms, cpu) = tfm; 392 } 393 394 return tfms; 395 396 error: 397 ipcomp_free_tfms(tfms); 398 return NULL; 399 } 400 401 static void ipcomp_free_data(struct ipcomp_data *ipcd) 402 { 403 if (ipcd->tfms) 404 ipcomp_free_tfms(ipcd->tfms); 405 ipcomp_free_scratches(); 406 } 407 408 static void ipcomp_destroy(struct xfrm_state *x) 409 { 410 struct ipcomp_data *ipcd = x->data; 411 if (!ipcd) 412 return; 413 xfrm_state_delete_tunnel(x); 414 down(&ipcomp_resource_sem); 415 ipcomp_free_data(ipcd); 416 up(&ipcomp_resource_sem); 417 kfree(ipcd); 418 } 419 420 static int ipcomp_init_state(struct xfrm_state *x) 421 { 422 int err; 423 struct ipcomp_data *ipcd; 424 struct xfrm_algo_desc *calg_desc; 425 426 err = -EINVAL; 427 if (!x->calg) 428 goto out; 429 430 if (x->encap) 431 goto out; 432 433 err = -ENOMEM; 434 ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL); 435 if (!ipcd) 436 goto out; 437 438 memset(ipcd, 0, sizeof(*ipcd)); 439 x->props.header_len = 0; 440 if (x->props.mode) 441 x->props.header_len += sizeof(struct iphdr); 442 443 down(&ipcomp_resource_sem); 444 if (!ipcomp_alloc_scratches()) 445 goto error; 446 447 ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name); 448 if (!ipcd->tfms) 449 goto error; 450 up(&ipcomp_resource_sem); 451 452 if (x->props.mode) { 453 err = ipcomp_tunnel_attach(x); 454 if (err) 455 goto error_tunnel; 456 } 457 458 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0); 459 BUG_ON(!calg_desc); 460 ipcd->threshold = calg_desc->uinfo.comp.threshold; 461 x->data = ipcd; 462 err = 0; 463 out: 464 return err; 465 466 error_tunnel: 467 down(&ipcomp_resource_sem); 468 error: 469 ipcomp_free_data(ipcd); 470 up(&ipcomp_resource_sem); 471 kfree(ipcd); 472 goto out; 473 } 474 475 static struct xfrm_type ipcomp_type = { 476 .description = "IPCOMP4", 477 .owner = THIS_MODULE, 478 .proto = IPPROTO_COMP, 479 .init_state = ipcomp_init_state, 480 .destructor = ipcomp_destroy, 481 .input = ipcomp_input, 482 .output = ipcomp_output 483 }; 484 485 static struct net_protocol ipcomp4_protocol = { 486 .handler = xfrm4_rcv, 487 .err_handler = ipcomp4_err, 488 .no_policy = 1, 489 }; 490 491 static int __init ipcomp4_init(void) 492 { 493 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) { 494 printk(KERN_INFO "ipcomp init: can't add xfrm type\n"); 495 return -EAGAIN; 496 } 497 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) { 498 printk(KERN_INFO "ipcomp init: can't add protocol\n"); 499 xfrm_unregister_type(&ipcomp_type, AF_INET); 500 return -EAGAIN; 501 } 502 return 0; 503 } 504 505 static void __exit ipcomp4_fini(void) 506 { 507 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) 508 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n"); 509 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0) 510 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n"); 511 } 512 513 module_init(ipcomp4_init); 514 module_exit(ipcomp4_fini); 515 516 MODULE_LICENSE("GPL"); 517 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173"); 518 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); 519 520