1 #include <crypto/hash.h> 2 #include <linux/err.h> 3 #include <linux/module.h> 4 #include <linux/slab.h> 5 #include <net/ip.h> 6 #include <net/xfrm.h> 7 #include <net/ah.h> 8 #include <linux/crypto.h> 9 #include <linux/pfkeyv2.h> 10 #include <linux/scatterlist.h> 11 #include <net/icmp.h> 12 #include <net/protocol.h> 13 14 struct ah_skb_cb { 15 struct xfrm_skb_cb xfrm; 16 void *tmp; 17 }; 18 19 #define AH_SKB_CB(__skb) ((struct ah_skb_cb *)&((__skb)->cb[0])) 20 21 static void *ah_alloc_tmp(struct crypto_ahash *ahash, int nfrags, 22 unsigned int size) 23 { 24 unsigned int len; 25 26 len = size + crypto_ahash_digestsize(ahash) + 27 (crypto_ahash_alignmask(ahash) & 28 ~(crypto_tfm_ctx_alignment() - 1)); 29 30 len = ALIGN(len, crypto_tfm_ctx_alignment()); 31 32 len += sizeof(struct ahash_request) + crypto_ahash_reqsize(ahash); 33 len = ALIGN(len, __alignof__(struct scatterlist)); 34 35 len += sizeof(struct scatterlist) * nfrags; 36 37 return kmalloc(len, GFP_ATOMIC); 38 } 39 40 static inline u8 *ah_tmp_auth(void *tmp, unsigned int offset) 41 { 42 return tmp + offset; 43 } 44 45 static inline u8 *ah_tmp_icv(struct crypto_ahash *ahash, void *tmp, 46 unsigned int offset) 47 { 48 return PTR_ALIGN((u8 *)tmp + offset, crypto_ahash_alignmask(ahash) + 1); 49 } 50 51 static inline struct ahash_request *ah_tmp_req(struct crypto_ahash *ahash, 52 u8 *icv) 53 { 54 struct ahash_request *req; 55 56 req = (void *)PTR_ALIGN(icv + crypto_ahash_digestsize(ahash), 57 crypto_tfm_ctx_alignment()); 58 59 ahash_request_set_tfm(req, ahash); 60 61 return req; 62 } 63 64 static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash, 65 struct ahash_request *req) 66 { 67 return (void *)ALIGN((unsigned long)(req + 1) + 68 crypto_ahash_reqsize(ahash), 69 __alignof__(struct scatterlist)); 70 } 71 72 /* Clear mutable options and find final destination to substitute 73 * into IP header for icv calculation. Options are already checked 74 * for validity, so paranoia is not required. */ 75 76 static int ip_clear_mutable_options(struct iphdr *iph, __be32 *daddr) 77 { 78 unsigned char * optptr = (unsigned char*)(iph+1); 79 int l = iph->ihl*4 - sizeof(struct iphdr); 80 int optlen; 81 82 while (l > 0) { 83 switch (*optptr) { 84 case IPOPT_END: 85 return 0; 86 case IPOPT_NOOP: 87 l--; 88 optptr++; 89 continue; 90 } 91 optlen = optptr[1]; 92 if (optlen<2 || optlen>l) 93 return -EINVAL; 94 switch (*optptr) { 95 case IPOPT_SEC: 96 case 0x85: /* Some "Extended Security" crap. */ 97 case IPOPT_CIPSO: 98 case IPOPT_RA: 99 case 0x80|21: /* RFC1770 */ 100 break; 101 case IPOPT_LSRR: 102 case IPOPT_SSRR: 103 if (optlen < 6) 104 return -EINVAL; 105 memcpy(daddr, optptr+optlen-4, 4); 106 /* Fall through */ 107 default: 108 memset(optptr, 0, optlen); 109 } 110 l -= optlen; 111 optptr += optlen; 112 } 113 return 0; 114 } 115 116 static void ah_output_done(struct crypto_async_request *base, int err) 117 { 118 u8 *icv; 119 struct iphdr *iph; 120 struct sk_buff *skb = base->data; 121 struct xfrm_state *x = skb_dst(skb)->xfrm; 122 struct ah_data *ahp = x->data; 123 struct iphdr *top_iph = ip_hdr(skb); 124 struct ip_auth_hdr *ah = ip_auth_hdr(skb); 125 int ihl = ip_hdrlen(skb); 126 127 iph = AH_SKB_CB(skb)->tmp; 128 icv = ah_tmp_icv(ahp->ahash, iph, ihl); 129 memcpy(ah->auth_data, icv, ahp->icv_trunc_len); 130 131 top_iph->tos = iph->tos; 132 top_iph->ttl = iph->ttl; 133 top_iph->frag_off = iph->frag_off; 134 if (top_iph->ihl != 5) { 135 top_iph->daddr = iph->daddr; 136 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); 137 } 138 139 err = ah->nexthdr; 140 141 kfree(AH_SKB_CB(skb)->tmp); 142 xfrm_output_resume(skb, err); 143 } 144 145 static int ah_output(struct xfrm_state *x, struct sk_buff *skb) 146 { 147 int err; 148 int nfrags; 149 int ihl; 150 u8 *icv; 151 struct sk_buff *trailer; 152 struct crypto_ahash *ahash; 153 struct ahash_request *req; 154 struct scatterlist *sg; 155 struct iphdr *iph, *top_iph; 156 struct ip_auth_hdr *ah; 157 struct ah_data *ahp; 158 159 ahp = x->data; 160 ahash = ahp->ahash; 161 162 if ((err = skb_cow_data(skb, 0, &trailer)) < 0) 163 goto out; 164 nfrags = err; 165 166 skb_push(skb, -skb_network_offset(skb)); 167 ah = ip_auth_hdr(skb); 168 ihl = ip_hdrlen(skb); 169 170 err = -ENOMEM; 171 iph = ah_alloc_tmp(ahash, nfrags, ihl); 172 if (!iph) 173 goto out; 174 175 icv = ah_tmp_icv(ahash, iph, ihl); 176 req = ah_tmp_req(ahash, icv); 177 sg = ah_req_sg(ahash, req); 178 179 memset(ah->auth_data, 0, ahp->icv_trunc_len); 180 181 top_iph = ip_hdr(skb); 182 183 iph->tos = top_iph->tos; 184 iph->ttl = top_iph->ttl; 185 iph->frag_off = top_iph->frag_off; 186 187 if (top_iph->ihl != 5) { 188 iph->daddr = top_iph->daddr; 189 memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); 190 err = ip_clear_mutable_options(top_iph, &top_iph->daddr); 191 if (err) 192 goto out_free; 193 } 194 195 ah->nexthdr = *skb_mac_header(skb); 196 *skb_mac_header(skb) = IPPROTO_AH; 197 198 top_iph->tos = 0; 199 top_iph->tot_len = htons(skb->len); 200 top_iph->frag_off = 0; 201 top_iph->ttl = 0; 202 top_iph->check = 0; 203 204 if (x->props.flags & XFRM_STATE_ALIGN4) 205 ah->hdrlen = (XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2; 206 else 207 ah->hdrlen = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2; 208 209 ah->reserved = 0; 210 ah->spi = x->id.spi; 211 ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low); 212 213 sg_init_table(sg, nfrags); 214 skb_to_sgvec(skb, sg, 0, skb->len); 215 216 ahash_request_set_crypt(req, sg, icv, skb->len); 217 ahash_request_set_callback(req, 0, ah_output_done, skb); 218 219 AH_SKB_CB(skb)->tmp = iph; 220 221 err = crypto_ahash_digest(req); 222 if (err) { 223 if (err == -EINPROGRESS) 224 goto out; 225 226 if (err == -EBUSY) 227 err = NET_XMIT_DROP; 228 goto out_free; 229 } 230 231 memcpy(ah->auth_data, icv, ahp->icv_trunc_len); 232 233 top_iph->tos = iph->tos; 234 top_iph->ttl = iph->ttl; 235 top_iph->frag_off = iph->frag_off; 236 if (top_iph->ihl != 5) { 237 top_iph->daddr = iph->daddr; 238 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); 239 } 240 241 out_free: 242 kfree(iph); 243 out: 244 return err; 245 } 246 247 static void ah_input_done(struct crypto_async_request *base, int err) 248 { 249 u8 *auth_data; 250 u8 *icv; 251 struct iphdr *work_iph; 252 struct sk_buff *skb = base->data; 253 struct xfrm_state *x = xfrm_input_state(skb); 254 struct ah_data *ahp = x->data; 255 struct ip_auth_hdr *ah = ip_auth_hdr(skb); 256 int ihl = ip_hdrlen(skb); 257 int ah_hlen = (ah->hdrlen + 2) << 2; 258 259 work_iph = AH_SKB_CB(skb)->tmp; 260 auth_data = ah_tmp_auth(work_iph, ihl); 261 icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len); 262 263 err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0; 264 if (err) 265 goto out; 266 267 skb->network_header += ah_hlen; 268 memcpy(skb_network_header(skb), work_iph, ihl); 269 __skb_pull(skb, ah_hlen + ihl); 270 skb_set_transport_header(skb, -ihl); 271 272 err = ah->nexthdr; 273 out: 274 kfree(AH_SKB_CB(skb)->tmp); 275 xfrm_input_resume(skb, err); 276 } 277 278 static int ah_input(struct xfrm_state *x, struct sk_buff *skb) 279 { 280 int ah_hlen; 281 int ihl; 282 int nexthdr; 283 int nfrags; 284 u8 *auth_data; 285 u8 *icv; 286 struct sk_buff *trailer; 287 struct crypto_ahash *ahash; 288 struct ahash_request *req; 289 struct scatterlist *sg; 290 struct iphdr *iph, *work_iph; 291 struct ip_auth_hdr *ah; 292 struct ah_data *ahp; 293 int err = -ENOMEM; 294 295 if (!pskb_may_pull(skb, sizeof(*ah))) 296 goto out; 297 298 ah = (struct ip_auth_hdr *)skb->data; 299 ahp = x->data; 300 ahash = ahp->ahash; 301 302 nexthdr = ah->nexthdr; 303 ah_hlen = (ah->hdrlen + 2) << 2; 304 305 if (x->props.flags & XFRM_STATE_ALIGN4) { 306 if (ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_full_len) && 307 ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len)) 308 goto out; 309 } else { 310 if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) && 311 ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len)) 312 goto out; 313 } 314 315 if (!pskb_may_pull(skb, ah_hlen)) 316 goto out; 317 318 /* We are going to _remove_ AH header to keep sockets happy, 319 * so... Later this can change. */ 320 if (skb_cloned(skb) && 321 pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) 322 goto out; 323 324 skb->ip_summed = CHECKSUM_NONE; 325 326 327 if ((err = skb_cow_data(skb, 0, &trailer)) < 0) 328 goto out; 329 nfrags = err; 330 331 ah = (struct ip_auth_hdr *)skb->data; 332 iph = ip_hdr(skb); 333 ihl = ip_hdrlen(skb); 334 335 work_iph = ah_alloc_tmp(ahash, nfrags, ihl + ahp->icv_trunc_len); 336 if (!work_iph) 337 goto out; 338 339 auth_data = ah_tmp_auth(work_iph, ihl); 340 icv = ah_tmp_icv(ahash, auth_data, ahp->icv_trunc_len); 341 req = ah_tmp_req(ahash, icv); 342 sg = ah_req_sg(ahash, req); 343 344 memcpy(work_iph, iph, ihl); 345 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len); 346 memset(ah->auth_data, 0, ahp->icv_trunc_len); 347 348 iph->ttl = 0; 349 iph->tos = 0; 350 iph->frag_off = 0; 351 iph->check = 0; 352 if (ihl > sizeof(*iph)) { 353 __be32 dummy; 354 err = ip_clear_mutable_options(iph, &dummy); 355 if (err) 356 goto out_free; 357 } 358 359 skb_push(skb, ihl); 360 361 sg_init_table(sg, nfrags); 362 skb_to_sgvec(skb, sg, 0, skb->len); 363 364 ahash_request_set_crypt(req, sg, icv, skb->len); 365 ahash_request_set_callback(req, 0, ah_input_done, skb); 366 367 AH_SKB_CB(skb)->tmp = work_iph; 368 369 err = crypto_ahash_digest(req); 370 if (err) { 371 if (err == -EINPROGRESS) 372 goto out; 373 374 if (err == -EBUSY) 375 err = NET_XMIT_DROP; 376 goto out_free; 377 } 378 379 err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0; 380 if (err) 381 goto out_free; 382 383 skb->network_header += ah_hlen; 384 memcpy(skb_network_header(skb), work_iph, ihl); 385 __skb_pull(skb, ah_hlen + ihl); 386 skb_set_transport_header(skb, -ihl); 387 388 err = nexthdr; 389 390 out_free: 391 kfree (work_iph); 392 out: 393 return err; 394 } 395 396 static void ah4_err(struct sk_buff *skb, u32 info) 397 { 398 struct net *net = dev_net(skb->dev); 399 struct iphdr *iph = (struct iphdr *)skb->data; 400 struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+(iph->ihl<<2)); 401 struct xfrm_state *x; 402 403 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH || 404 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) 405 return; 406 407 x = xfrm_state_lookup(net, skb->mark, (xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET); 408 if (!x) 409 return; 410 printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n", 411 ntohl(ah->spi), ntohl(iph->daddr)); 412 xfrm_state_put(x); 413 } 414 415 static int ah_init_state(struct xfrm_state *x) 416 { 417 struct ah_data *ahp = NULL; 418 struct xfrm_algo_desc *aalg_desc; 419 struct crypto_ahash *ahash; 420 421 if (!x->aalg) 422 goto error; 423 424 if (x->encap) 425 goto error; 426 427 ahp = kzalloc(sizeof(*ahp), GFP_KERNEL); 428 if (!ahp) 429 return -ENOMEM; 430 431 ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0); 432 if (IS_ERR(ahash)) 433 goto error; 434 435 ahp->ahash = ahash; 436 if (crypto_ahash_setkey(ahash, x->aalg->alg_key, 437 (x->aalg->alg_key_len + 7) / 8)) 438 goto error; 439 440 /* 441 * Lookup the algorithm description maintained by xfrm_algo, 442 * verify crypto transform properties, and store information 443 * we need for AH processing. This lookup cannot fail here 444 * after a successful crypto_alloc_ahash(). 445 */ 446 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 447 BUG_ON(!aalg_desc); 448 449 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 450 crypto_ahash_digestsize(ahash)) { 451 printk(KERN_INFO "AH: %s digestsize %u != %hu\n", 452 x->aalg->alg_name, crypto_ahash_digestsize(ahash), 453 aalg_desc->uinfo.auth.icv_fullbits/8); 454 goto error; 455 } 456 457 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 458 ahp->icv_trunc_len = x->aalg->alg_trunc_len/8; 459 460 BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN); 461 462 if (x->props.flags & XFRM_STATE_ALIGN4) 463 x->props.header_len = XFRM_ALIGN4(sizeof(struct ip_auth_hdr) + 464 ahp->icv_trunc_len); 465 else 466 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + 467 ahp->icv_trunc_len); 468 if (x->props.mode == XFRM_MODE_TUNNEL) 469 x->props.header_len += sizeof(struct iphdr); 470 x->data = ahp; 471 472 return 0; 473 474 error: 475 if (ahp) { 476 crypto_free_ahash(ahp->ahash); 477 kfree(ahp); 478 } 479 return -EINVAL; 480 } 481 482 static void ah_destroy(struct xfrm_state *x) 483 { 484 struct ah_data *ahp = x->data; 485 486 if (!ahp) 487 return; 488 489 crypto_free_ahash(ahp->ahash); 490 kfree(ahp); 491 } 492 493 494 static const struct xfrm_type ah_type = 495 { 496 .description = "AH4", 497 .owner = THIS_MODULE, 498 .proto = IPPROTO_AH, 499 .flags = XFRM_TYPE_REPLAY_PROT, 500 .init_state = ah_init_state, 501 .destructor = ah_destroy, 502 .input = ah_input, 503 .output = ah_output 504 }; 505 506 static const struct net_protocol ah4_protocol = { 507 .handler = xfrm4_rcv, 508 .err_handler = ah4_err, 509 .no_policy = 1, 510 .netns_ok = 1, 511 }; 512 513 static int __init ah4_init(void) 514 { 515 if (xfrm_register_type(&ah_type, AF_INET) < 0) { 516 printk(KERN_INFO "ip ah init: can't add xfrm type\n"); 517 return -EAGAIN; 518 } 519 if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) { 520 printk(KERN_INFO "ip ah init: can't add protocol\n"); 521 xfrm_unregister_type(&ah_type, AF_INET); 522 return -EAGAIN; 523 } 524 return 0; 525 } 526 527 static void __exit ah4_fini(void) 528 { 529 if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0) 530 printk(KERN_INFO "ip ah close: can't remove protocol\n"); 531 if (xfrm_unregister_type(&ah_type, AF_INET) < 0) 532 printk(KERN_INFO "ip ah close: can't remove xfrm type\n"); 533 } 534 535 module_init(ah4_init); 536 module_exit(ah4_fini); 537 MODULE_LICENSE("GPL"); 538 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH); 539