1 #define pr_fmt(fmt) "IPsec: " fmt 2 3 #include <crypto/hash.h> 4 #include <linux/err.h> 5 #include <linux/module.h> 6 #include <linux/slab.h> 7 #include <net/ip.h> 8 #include <net/xfrm.h> 9 #include <net/ah.h> 10 #include <linux/crypto.h> 11 #include <linux/pfkeyv2.h> 12 #include <linux/scatterlist.h> 13 #include <net/icmp.h> 14 #include <net/protocol.h> 15 16 struct ah_skb_cb { 17 struct xfrm_skb_cb xfrm; 18 void *tmp; 19 }; 20 21 #define AH_SKB_CB(__skb) ((struct ah_skb_cb *)&((__skb)->cb[0])) 22 23 static void *ah_alloc_tmp(struct crypto_ahash *ahash, int nfrags, 24 unsigned int size) 25 { 26 unsigned int len; 27 28 len = size + crypto_ahash_digestsize(ahash) + 29 (crypto_ahash_alignmask(ahash) & 30 ~(crypto_tfm_ctx_alignment() - 1)); 31 32 len = ALIGN(len, crypto_tfm_ctx_alignment()); 33 34 len += sizeof(struct ahash_request) + crypto_ahash_reqsize(ahash); 35 len = ALIGN(len, __alignof__(struct scatterlist)); 36 37 len += sizeof(struct scatterlist) * nfrags; 38 39 return kmalloc(len, GFP_ATOMIC); 40 } 41 42 static inline u8 *ah_tmp_auth(void *tmp, unsigned int offset) 43 { 44 return tmp + offset; 45 } 46 47 static inline u8 *ah_tmp_icv(struct crypto_ahash *ahash, void *tmp, 48 unsigned int offset) 49 { 50 return PTR_ALIGN((u8 *)tmp + offset, crypto_ahash_alignmask(ahash) + 1); 51 } 52 53 static inline struct ahash_request *ah_tmp_req(struct crypto_ahash *ahash, 54 u8 *icv) 55 { 56 struct ahash_request *req; 57 58 req = (void *)PTR_ALIGN(icv + crypto_ahash_digestsize(ahash), 59 crypto_tfm_ctx_alignment()); 60 61 ahash_request_set_tfm(req, ahash); 62 63 return req; 64 } 65 66 static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash, 67 struct ahash_request *req) 68 { 69 return (void *)ALIGN((unsigned long)(req + 1) + 70 crypto_ahash_reqsize(ahash), 71 __alignof__(struct scatterlist)); 72 } 73 74 /* Clear mutable options and find final destination to substitute 75 * into IP header for icv calculation. Options are already checked 76 * for validity, so paranoia is not required. */ 77 78 static int ip_clear_mutable_options(const struct iphdr *iph, __be32 *daddr) 79 { 80 unsigned char *optptr = (unsigned char *)(iph+1); 81 int l = iph->ihl*4 - sizeof(struct iphdr); 82 int optlen; 83 84 while (l > 0) { 85 switch (*optptr) { 86 case IPOPT_END: 87 return 0; 88 case IPOPT_NOOP: 89 l--; 90 optptr++; 91 continue; 92 } 93 optlen = optptr[1]; 94 if (optlen<2 || optlen>l) 95 return -EINVAL; 96 switch (*optptr) { 97 case IPOPT_SEC: 98 case 0x85: /* Some "Extended Security" crap. */ 99 case IPOPT_CIPSO: 100 case IPOPT_RA: 101 case 0x80|21: /* RFC1770 */ 102 break; 103 case IPOPT_LSRR: 104 case IPOPT_SSRR: 105 if (optlen < 6) 106 return -EINVAL; 107 memcpy(daddr, optptr+optlen-4, 4); 108 /* Fall through */ 109 default: 110 memset(optptr, 0, optlen); 111 } 112 l -= optlen; 113 optptr += optlen; 114 } 115 return 0; 116 } 117 118 static void ah_output_done(struct crypto_async_request *base, int err) 119 { 120 u8 *icv; 121 struct iphdr *iph; 122 struct sk_buff *skb = base->data; 123 struct xfrm_state *x = skb_dst(skb)->xfrm; 124 struct ah_data *ahp = x->data; 125 struct iphdr *top_iph = ip_hdr(skb); 126 struct ip_auth_hdr *ah = ip_auth_hdr(skb); 127 int ihl = ip_hdrlen(skb); 128 129 iph = AH_SKB_CB(skb)->tmp; 130 icv = ah_tmp_icv(ahp->ahash, iph, ihl); 131 memcpy(ah->auth_data, icv, ahp->icv_trunc_len); 132 133 top_iph->tos = iph->tos; 134 top_iph->ttl = iph->ttl; 135 top_iph->frag_off = iph->frag_off; 136 if (top_iph->ihl != 5) { 137 top_iph->daddr = iph->daddr; 138 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); 139 } 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 int seqhi_len = 0; 159 __be32 *seqhi; 160 int sglists = 0; 161 struct scatterlist *seqhisg; 162 163 ahp = x->data; 164 ahash = ahp->ahash; 165 166 if ((err = skb_cow_data(skb, 0, &trailer)) < 0) 167 goto out; 168 nfrags = err; 169 170 skb_push(skb, -skb_network_offset(skb)); 171 ah = ip_auth_hdr(skb); 172 ihl = ip_hdrlen(skb); 173 174 if (x->props.flags & XFRM_STATE_ESN) { 175 sglists = 1; 176 seqhi_len = sizeof(*seqhi); 177 } 178 err = -ENOMEM; 179 iph = ah_alloc_tmp(ahash, nfrags + sglists, ihl + seqhi_len); 180 if (!iph) 181 goto out; 182 seqhi = (__be32 *)((char *)iph + ihl); 183 icv = ah_tmp_icv(ahash, seqhi, seqhi_len); 184 req = ah_tmp_req(ahash, icv); 185 sg = ah_req_sg(ahash, req); 186 seqhisg = sg + nfrags; 187 188 memset(ah->auth_data, 0, ahp->icv_trunc_len); 189 190 top_iph = ip_hdr(skb); 191 192 iph->tos = top_iph->tos; 193 iph->ttl = top_iph->ttl; 194 iph->frag_off = top_iph->frag_off; 195 196 if (top_iph->ihl != 5) { 197 iph->daddr = top_iph->daddr; 198 memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); 199 err = ip_clear_mutable_options(top_iph, &top_iph->daddr); 200 if (err) 201 goto out_free; 202 } 203 204 ah->nexthdr = *skb_mac_header(skb); 205 *skb_mac_header(skb) = IPPROTO_AH; 206 207 top_iph->tos = 0; 208 top_iph->tot_len = htons(skb->len); 209 top_iph->frag_off = 0; 210 top_iph->ttl = 0; 211 top_iph->check = 0; 212 213 if (x->props.flags & XFRM_STATE_ALIGN4) 214 ah->hdrlen = (XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2; 215 else 216 ah->hdrlen = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2; 217 218 ah->reserved = 0; 219 ah->spi = x->id.spi; 220 ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low); 221 222 sg_init_table(sg, nfrags + sglists); 223 skb_to_sgvec_nomark(skb, sg, 0, skb->len); 224 225 if (x->props.flags & XFRM_STATE_ESN) { 226 /* Attach seqhi sg right after packet payload */ 227 *seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi); 228 sg_set_buf(seqhisg, seqhi, seqhi_len); 229 } 230 ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len); 231 ahash_request_set_callback(req, 0, ah_output_done, skb); 232 233 AH_SKB_CB(skb)->tmp = iph; 234 235 err = crypto_ahash_digest(req); 236 if (err) { 237 if (err == -EINPROGRESS) 238 goto out; 239 240 if (err == -EBUSY) 241 err = NET_XMIT_DROP; 242 goto out_free; 243 } 244 245 memcpy(ah->auth_data, icv, ahp->icv_trunc_len); 246 247 top_iph->tos = iph->tos; 248 top_iph->ttl = iph->ttl; 249 top_iph->frag_off = iph->frag_off; 250 if (top_iph->ihl != 5) { 251 top_iph->daddr = iph->daddr; 252 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); 253 } 254 255 out_free: 256 kfree(iph); 257 out: 258 return err; 259 } 260 261 static void ah_input_done(struct crypto_async_request *base, int err) 262 { 263 u8 *auth_data; 264 u8 *icv; 265 struct iphdr *work_iph; 266 struct sk_buff *skb = base->data; 267 struct xfrm_state *x = xfrm_input_state(skb); 268 struct ah_data *ahp = x->data; 269 struct ip_auth_hdr *ah = ip_auth_hdr(skb); 270 int ihl = ip_hdrlen(skb); 271 int ah_hlen = (ah->hdrlen + 2) << 2; 272 273 if (err) 274 goto out; 275 276 work_iph = AH_SKB_CB(skb)->tmp; 277 auth_data = ah_tmp_auth(work_iph, ihl); 278 icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len); 279 280 err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0; 281 if (err) 282 goto out; 283 284 err = ah->nexthdr; 285 286 skb->network_header += ah_hlen; 287 memcpy(skb_network_header(skb), work_iph, ihl); 288 __skb_pull(skb, ah_hlen + ihl); 289 290 if (x->props.mode == XFRM_MODE_TUNNEL) 291 skb_reset_transport_header(skb); 292 else 293 skb_set_transport_header(skb, -ihl); 294 out: 295 kfree(AH_SKB_CB(skb)->tmp); 296 xfrm_input_resume(skb, err); 297 } 298 299 static int ah_input(struct xfrm_state *x, struct sk_buff *skb) 300 { 301 int ah_hlen; 302 int ihl; 303 int nexthdr; 304 int nfrags; 305 u8 *auth_data; 306 u8 *icv; 307 struct sk_buff *trailer; 308 struct crypto_ahash *ahash; 309 struct ahash_request *req; 310 struct scatterlist *sg; 311 struct iphdr *iph, *work_iph; 312 struct ip_auth_hdr *ah; 313 struct ah_data *ahp; 314 int err = -ENOMEM; 315 int seqhi_len = 0; 316 __be32 *seqhi; 317 int sglists = 0; 318 struct scatterlist *seqhisg; 319 320 if (!pskb_may_pull(skb, sizeof(*ah))) 321 goto out; 322 323 ah = (struct ip_auth_hdr *)skb->data; 324 ahp = x->data; 325 ahash = ahp->ahash; 326 327 nexthdr = ah->nexthdr; 328 ah_hlen = (ah->hdrlen + 2) << 2; 329 330 if (x->props.flags & XFRM_STATE_ALIGN4) { 331 if (ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_full_len) && 332 ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len)) 333 goto out; 334 } else { 335 if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) && 336 ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len)) 337 goto out; 338 } 339 340 if (!pskb_may_pull(skb, ah_hlen)) 341 goto out; 342 343 /* We are going to _remove_ AH header to keep sockets happy, 344 * so... Later this can change. */ 345 if (skb_unclone(skb, GFP_ATOMIC)) 346 goto out; 347 348 skb->ip_summed = CHECKSUM_NONE; 349 350 351 if ((err = skb_cow_data(skb, 0, &trailer)) < 0) 352 goto out; 353 nfrags = err; 354 355 ah = (struct ip_auth_hdr *)skb->data; 356 iph = ip_hdr(skb); 357 ihl = ip_hdrlen(skb); 358 359 if (x->props.flags & XFRM_STATE_ESN) { 360 sglists = 1; 361 seqhi_len = sizeof(*seqhi); 362 } 363 364 work_iph = ah_alloc_tmp(ahash, nfrags + sglists, ihl + 365 ahp->icv_trunc_len + seqhi_len); 366 if (!work_iph) { 367 err = -ENOMEM; 368 goto out; 369 } 370 371 seqhi = (__be32 *)((char *)work_iph + ihl); 372 auth_data = ah_tmp_auth(seqhi, seqhi_len); 373 icv = ah_tmp_icv(ahash, auth_data, ahp->icv_trunc_len); 374 req = ah_tmp_req(ahash, icv); 375 sg = ah_req_sg(ahash, req); 376 seqhisg = sg + nfrags; 377 378 memcpy(work_iph, iph, ihl); 379 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len); 380 memset(ah->auth_data, 0, ahp->icv_trunc_len); 381 382 iph->ttl = 0; 383 iph->tos = 0; 384 iph->frag_off = 0; 385 iph->check = 0; 386 if (ihl > sizeof(*iph)) { 387 __be32 dummy; 388 err = ip_clear_mutable_options(iph, &dummy); 389 if (err) 390 goto out_free; 391 } 392 393 skb_push(skb, ihl); 394 395 sg_init_table(sg, nfrags + sglists); 396 skb_to_sgvec_nomark(skb, sg, 0, skb->len); 397 398 if (x->props.flags & XFRM_STATE_ESN) { 399 /* Attach seqhi sg right after packet payload */ 400 *seqhi = XFRM_SKB_CB(skb)->seq.input.hi; 401 sg_set_buf(seqhisg, seqhi, seqhi_len); 402 } 403 ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len); 404 ahash_request_set_callback(req, 0, ah_input_done, skb); 405 406 AH_SKB_CB(skb)->tmp = work_iph; 407 408 err = crypto_ahash_digest(req); 409 if (err) { 410 if (err == -EINPROGRESS) 411 goto out; 412 413 goto out_free; 414 } 415 416 err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0; 417 if (err) 418 goto out_free; 419 420 skb->network_header += ah_hlen; 421 memcpy(skb_network_header(skb), work_iph, ihl); 422 __skb_pull(skb, ah_hlen + ihl); 423 if (x->props.mode == XFRM_MODE_TUNNEL) 424 skb_reset_transport_header(skb); 425 else 426 skb_set_transport_header(skb, -ihl); 427 428 err = nexthdr; 429 430 out_free: 431 kfree (work_iph); 432 out: 433 return err; 434 } 435 436 static int ah4_err(struct sk_buff *skb, u32 info) 437 { 438 struct net *net = dev_net(skb->dev); 439 const struct iphdr *iph = (const struct iphdr *)skb->data; 440 struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+(iph->ihl<<2)); 441 struct xfrm_state *x; 442 443 switch (icmp_hdr(skb)->type) { 444 case ICMP_DEST_UNREACH: 445 if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) 446 return 0; 447 case ICMP_REDIRECT: 448 break; 449 default: 450 return 0; 451 } 452 453 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr, 454 ah->spi, IPPROTO_AH, AF_INET); 455 if (!x) 456 return 0; 457 458 if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH) 459 ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_AH, 0); 460 else 461 ipv4_redirect(skb, net, 0, 0, IPPROTO_AH, 0); 462 xfrm_state_put(x); 463 464 return 0; 465 } 466 467 static int ah_init_state(struct xfrm_state *x) 468 { 469 struct ah_data *ahp = NULL; 470 struct xfrm_algo_desc *aalg_desc; 471 struct crypto_ahash *ahash; 472 473 if (!x->aalg) 474 goto error; 475 476 if (x->encap) 477 goto error; 478 479 ahp = kzalloc(sizeof(*ahp), GFP_KERNEL); 480 if (!ahp) 481 return -ENOMEM; 482 483 ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0); 484 if (IS_ERR(ahash)) 485 goto error; 486 487 ahp->ahash = ahash; 488 if (crypto_ahash_setkey(ahash, x->aalg->alg_key, 489 (x->aalg->alg_key_len + 7) / 8)) 490 goto error; 491 492 /* 493 * Lookup the algorithm description maintained by xfrm_algo, 494 * verify crypto transform properties, and store information 495 * we need for AH processing. This lookup cannot fail here 496 * after a successful crypto_alloc_ahash(). 497 */ 498 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 499 BUG_ON(!aalg_desc); 500 501 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 502 crypto_ahash_digestsize(ahash)) { 503 pr_info("%s: %s digestsize %u != %hu\n", 504 __func__, x->aalg->alg_name, 505 crypto_ahash_digestsize(ahash), 506 aalg_desc->uinfo.auth.icv_fullbits / 8); 507 goto error; 508 } 509 510 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 511 ahp->icv_trunc_len = x->aalg->alg_trunc_len/8; 512 513 if (x->props.flags & XFRM_STATE_ALIGN4) 514 x->props.header_len = XFRM_ALIGN4(sizeof(struct ip_auth_hdr) + 515 ahp->icv_trunc_len); 516 else 517 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + 518 ahp->icv_trunc_len); 519 if (x->props.mode == XFRM_MODE_TUNNEL) 520 x->props.header_len += sizeof(struct iphdr); 521 x->data = ahp; 522 523 return 0; 524 525 error: 526 if (ahp) { 527 crypto_free_ahash(ahp->ahash); 528 kfree(ahp); 529 } 530 return -EINVAL; 531 } 532 533 static void ah_destroy(struct xfrm_state *x) 534 { 535 struct ah_data *ahp = x->data; 536 537 if (!ahp) 538 return; 539 540 crypto_free_ahash(ahp->ahash); 541 kfree(ahp); 542 } 543 544 static int ah4_rcv_cb(struct sk_buff *skb, int err) 545 { 546 return 0; 547 } 548 549 static const struct xfrm_type ah_type = 550 { 551 .description = "AH4", 552 .owner = THIS_MODULE, 553 .proto = IPPROTO_AH, 554 .flags = XFRM_TYPE_REPLAY_PROT, 555 .init_state = ah_init_state, 556 .destructor = ah_destroy, 557 .input = ah_input, 558 .output = ah_output 559 }; 560 561 static struct xfrm4_protocol ah4_protocol = { 562 .handler = xfrm4_rcv, 563 .input_handler = xfrm_input, 564 .cb_handler = ah4_rcv_cb, 565 .err_handler = ah4_err, 566 .priority = 0, 567 }; 568 569 static int __init ah4_init(void) 570 { 571 if (xfrm_register_type(&ah_type, AF_INET) < 0) { 572 pr_info("%s: can't add xfrm type\n", __func__); 573 return -EAGAIN; 574 } 575 if (xfrm4_protocol_register(&ah4_protocol, IPPROTO_AH) < 0) { 576 pr_info("%s: can't add protocol\n", __func__); 577 xfrm_unregister_type(&ah_type, AF_INET); 578 return -EAGAIN; 579 } 580 return 0; 581 } 582 583 static void __exit ah4_fini(void) 584 { 585 if (xfrm4_protocol_deregister(&ah4_protocol, IPPROTO_AH) < 0) 586 pr_info("%s: can't remove protocol\n", __func__); 587 if (xfrm_unregister_type(&ah_type, AF_INET) < 0) 588 pr_info("%s: can't remove xfrm type\n", __func__); 589 } 590 591 module_init(ah4_init); 592 module_exit(ah4_fini); 593 MODULE_LICENSE("GPL"); 594 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH); 595