1 #define pr_fmt(fmt) "IPsec: " fmt 2 3 #include <crypto/algapi.h> 4 #include <crypto/hash.h> 5 #include <linux/err.h> 6 #include <linux/module.h> 7 #include <linux/slab.h> 8 #include <net/ip.h> 9 #include <net/xfrm.h> 10 #include <net/ah.h> 11 #include <linux/crypto.h> 12 #include <linux/pfkeyv2.h> 13 #include <linux/scatterlist.h> 14 #include <net/icmp.h> 15 #include <net/protocol.h> 16 17 struct ah_skb_cb { 18 struct xfrm_skb_cb xfrm; 19 void *tmp; 20 }; 21 22 #define AH_SKB_CB(__skb) ((struct ah_skb_cb *)&((__skb)->cb[0])) 23 24 static void *ah_alloc_tmp(struct crypto_ahash *ahash, int nfrags, 25 unsigned int size) 26 { 27 unsigned int len; 28 29 len = size + crypto_ahash_digestsize(ahash) + 30 (crypto_ahash_alignmask(ahash) & 31 ~(crypto_tfm_ctx_alignment() - 1)); 32 33 len = ALIGN(len, crypto_tfm_ctx_alignment()); 34 35 len += sizeof(struct ahash_request) + crypto_ahash_reqsize(ahash); 36 len = ALIGN(len, __alignof__(struct scatterlist)); 37 38 len += sizeof(struct scatterlist) * nfrags; 39 40 return kmalloc(len, GFP_ATOMIC); 41 } 42 43 static inline u8 *ah_tmp_auth(void *tmp, unsigned int offset) 44 { 45 return tmp + offset; 46 } 47 48 static inline u8 *ah_tmp_icv(struct crypto_ahash *ahash, void *tmp, 49 unsigned int offset) 50 { 51 return PTR_ALIGN((u8 *)tmp + offset, crypto_ahash_alignmask(ahash) + 1); 52 } 53 54 static inline struct ahash_request *ah_tmp_req(struct crypto_ahash *ahash, 55 u8 *icv) 56 { 57 struct ahash_request *req; 58 59 req = (void *)PTR_ALIGN(icv + crypto_ahash_digestsize(ahash), 60 crypto_tfm_ctx_alignment()); 61 62 ahash_request_set_tfm(req, ahash); 63 64 return req; 65 } 66 67 static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash, 68 struct ahash_request *req) 69 { 70 return (void *)ALIGN((unsigned long)(req + 1) + 71 crypto_ahash_reqsize(ahash), 72 __alignof__(struct scatterlist)); 73 } 74 75 /* Clear mutable options and find final destination to substitute 76 * into IP header for icv calculation. Options are already checked 77 * for validity, so paranoia is not required. */ 78 79 static int ip_clear_mutable_options(const struct iphdr *iph, __be32 *daddr) 80 { 81 unsigned char *optptr = (unsigned char *)(iph+1); 82 int l = iph->ihl*4 - sizeof(struct iphdr); 83 int optlen; 84 85 while (l > 0) { 86 switch (*optptr) { 87 case IPOPT_END: 88 return 0; 89 case IPOPT_NOOP: 90 l--; 91 optptr++; 92 continue; 93 } 94 optlen = optptr[1]; 95 if (optlen<2 || optlen>l) 96 return -EINVAL; 97 switch (*optptr) { 98 case IPOPT_SEC: 99 case 0x85: /* Some "Extended Security" crap. */ 100 case IPOPT_CIPSO: 101 case IPOPT_RA: 102 case 0x80|21: /* RFC1770 */ 103 break; 104 case IPOPT_LSRR: 105 case IPOPT_SSRR: 106 if (optlen < 6) 107 return -EINVAL; 108 memcpy(daddr, optptr+optlen-4, 4); 109 /* Fall through */ 110 default: 111 memset(optptr, 0, optlen); 112 } 113 l -= optlen; 114 optptr += optlen; 115 } 116 return 0; 117 } 118 119 static void ah_output_done(struct crypto_async_request *base, int err) 120 { 121 u8 *icv; 122 struct iphdr *iph; 123 struct sk_buff *skb = base->data; 124 struct xfrm_state *x = skb_dst(skb)->xfrm; 125 struct ah_data *ahp = x->data; 126 struct iphdr *top_iph = ip_hdr(skb); 127 struct ip_auth_hdr *ah = ip_auth_hdr(skb); 128 int ihl = ip_hdrlen(skb); 129 130 iph = AH_SKB_CB(skb)->tmp; 131 icv = ah_tmp_icv(ahp->ahash, iph, ihl); 132 memcpy(ah->auth_data, icv, ahp->icv_trunc_len); 133 134 top_iph->tos = iph->tos; 135 top_iph->ttl = iph->ttl; 136 top_iph->frag_off = iph->frag_off; 137 if (top_iph->ihl != 5) { 138 top_iph->daddr = iph->daddr; 139 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); 140 } 141 142 kfree(AH_SKB_CB(skb)->tmp); 143 xfrm_output_resume(skb, err); 144 } 145 146 static int ah_output(struct xfrm_state *x, struct sk_buff *skb) 147 { 148 int err; 149 int nfrags; 150 int ihl; 151 u8 *icv; 152 struct sk_buff *trailer; 153 struct crypto_ahash *ahash; 154 struct ahash_request *req; 155 struct scatterlist *sg; 156 struct iphdr *iph, *top_iph; 157 struct ip_auth_hdr *ah; 158 struct ah_data *ahp; 159 int seqhi_len = 0; 160 __be32 *seqhi; 161 int sglists = 0; 162 struct scatterlist *seqhisg; 163 164 ahp = x->data; 165 ahash = ahp->ahash; 166 167 if ((err = skb_cow_data(skb, 0, &trailer)) < 0) 168 goto out; 169 nfrags = err; 170 171 skb_push(skb, -skb_network_offset(skb)); 172 ah = ip_auth_hdr(skb); 173 ihl = ip_hdrlen(skb); 174 175 if (x->props.flags & XFRM_STATE_ESN) { 176 sglists = 1; 177 seqhi_len = sizeof(*seqhi); 178 } 179 err = -ENOMEM; 180 iph = ah_alloc_tmp(ahash, nfrags + sglists, ihl + seqhi_len); 181 if (!iph) 182 goto out; 183 seqhi = (__be32 *)((char *)iph + ihl); 184 icv = ah_tmp_icv(ahash, seqhi, seqhi_len); 185 req = ah_tmp_req(ahash, icv); 186 sg = ah_req_sg(ahash, req); 187 seqhisg = sg + nfrags; 188 189 memset(ah->auth_data, 0, ahp->icv_trunc_len); 190 191 top_iph = ip_hdr(skb); 192 193 iph->tos = top_iph->tos; 194 iph->ttl = top_iph->ttl; 195 iph->frag_off = top_iph->frag_off; 196 197 if (top_iph->ihl != 5) { 198 iph->daddr = top_iph->daddr; 199 memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); 200 err = ip_clear_mutable_options(top_iph, &top_iph->daddr); 201 if (err) 202 goto out_free; 203 } 204 205 ah->nexthdr = *skb_mac_header(skb); 206 *skb_mac_header(skb) = IPPROTO_AH; 207 208 top_iph->tos = 0; 209 top_iph->tot_len = htons(skb->len); 210 top_iph->frag_off = 0; 211 top_iph->ttl = 0; 212 top_iph->check = 0; 213 214 if (x->props.flags & XFRM_STATE_ALIGN4) 215 ah->hdrlen = (XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2; 216 else 217 ah->hdrlen = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2; 218 219 ah->reserved = 0; 220 ah->spi = x->id.spi; 221 ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low); 222 223 sg_init_table(sg, nfrags + sglists); 224 err = skb_to_sgvec_nomark(skb, sg, 0, skb->len); 225 if (unlikely(err < 0)) 226 goto out_free; 227 228 if (x->props.flags & XFRM_STATE_ESN) { 229 /* Attach seqhi sg right after packet payload */ 230 *seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi); 231 sg_set_buf(seqhisg, seqhi, seqhi_len); 232 } 233 ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len); 234 ahash_request_set_callback(req, 0, ah_output_done, skb); 235 236 AH_SKB_CB(skb)->tmp = iph; 237 238 err = crypto_ahash_digest(req); 239 if (err) { 240 if (err == -EINPROGRESS) 241 goto out; 242 243 if (err == -EBUSY) 244 err = NET_XMIT_DROP; 245 goto out_free; 246 } 247 248 memcpy(ah->auth_data, icv, ahp->icv_trunc_len); 249 250 top_iph->tos = iph->tos; 251 top_iph->ttl = iph->ttl; 252 top_iph->frag_off = iph->frag_off; 253 if (top_iph->ihl != 5) { 254 top_iph->daddr = iph->daddr; 255 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); 256 } 257 258 out_free: 259 kfree(iph); 260 out: 261 return err; 262 } 263 264 static void ah_input_done(struct crypto_async_request *base, int err) 265 { 266 u8 *auth_data; 267 u8 *icv; 268 struct iphdr *work_iph; 269 struct sk_buff *skb = base->data; 270 struct xfrm_state *x = xfrm_input_state(skb); 271 struct ah_data *ahp = x->data; 272 struct ip_auth_hdr *ah = ip_auth_hdr(skb); 273 int ihl = ip_hdrlen(skb); 274 int ah_hlen = (ah->hdrlen + 2) << 2; 275 276 if (err) 277 goto out; 278 279 work_iph = AH_SKB_CB(skb)->tmp; 280 auth_data = ah_tmp_auth(work_iph, ihl); 281 icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len); 282 283 err = crypto_memneq(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0; 284 if (err) 285 goto out; 286 287 err = ah->nexthdr; 288 289 skb->network_header += ah_hlen; 290 memcpy(skb_network_header(skb), work_iph, ihl); 291 __skb_pull(skb, ah_hlen + ihl); 292 293 if (x->props.mode == XFRM_MODE_TUNNEL) 294 skb_reset_transport_header(skb); 295 else 296 skb_set_transport_header(skb, -ihl); 297 out: 298 kfree(AH_SKB_CB(skb)->tmp); 299 xfrm_input_resume(skb, err); 300 } 301 302 static int ah_input(struct xfrm_state *x, struct sk_buff *skb) 303 { 304 int ah_hlen; 305 int ihl; 306 int nexthdr; 307 int nfrags; 308 u8 *auth_data; 309 u8 *icv; 310 struct sk_buff *trailer; 311 struct crypto_ahash *ahash; 312 struct ahash_request *req; 313 struct scatterlist *sg; 314 struct iphdr *iph, *work_iph; 315 struct ip_auth_hdr *ah; 316 struct ah_data *ahp; 317 int err = -ENOMEM; 318 int seqhi_len = 0; 319 __be32 *seqhi; 320 int sglists = 0; 321 struct scatterlist *seqhisg; 322 323 if (!pskb_may_pull(skb, sizeof(*ah))) 324 goto out; 325 326 ah = (struct ip_auth_hdr *)skb->data; 327 ahp = x->data; 328 ahash = ahp->ahash; 329 330 nexthdr = ah->nexthdr; 331 ah_hlen = (ah->hdrlen + 2) << 2; 332 333 if (x->props.flags & XFRM_STATE_ALIGN4) { 334 if (ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_full_len) && 335 ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len)) 336 goto out; 337 } else { 338 if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) && 339 ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len)) 340 goto out; 341 } 342 343 if (!pskb_may_pull(skb, ah_hlen)) 344 goto out; 345 346 /* We are going to _remove_ AH header to keep sockets happy, 347 * so... Later this can change. */ 348 if (skb_unclone(skb, GFP_ATOMIC)) 349 goto out; 350 351 skb->ip_summed = CHECKSUM_NONE; 352 353 354 if ((err = skb_cow_data(skb, 0, &trailer)) < 0) 355 goto out; 356 nfrags = err; 357 358 ah = (struct ip_auth_hdr *)skb->data; 359 iph = ip_hdr(skb); 360 ihl = ip_hdrlen(skb); 361 362 if (x->props.flags & XFRM_STATE_ESN) { 363 sglists = 1; 364 seqhi_len = sizeof(*seqhi); 365 } 366 367 work_iph = ah_alloc_tmp(ahash, nfrags + sglists, ihl + 368 ahp->icv_trunc_len + seqhi_len); 369 if (!work_iph) { 370 err = -ENOMEM; 371 goto out; 372 } 373 374 seqhi = (__be32 *)((char *)work_iph + ihl); 375 auth_data = ah_tmp_auth(seqhi, seqhi_len); 376 icv = ah_tmp_icv(ahash, auth_data, ahp->icv_trunc_len); 377 req = ah_tmp_req(ahash, icv); 378 sg = ah_req_sg(ahash, req); 379 seqhisg = sg + nfrags; 380 381 memcpy(work_iph, iph, ihl); 382 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len); 383 memset(ah->auth_data, 0, ahp->icv_trunc_len); 384 385 iph->ttl = 0; 386 iph->tos = 0; 387 iph->frag_off = 0; 388 iph->check = 0; 389 if (ihl > sizeof(*iph)) { 390 __be32 dummy; 391 err = ip_clear_mutable_options(iph, &dummy); 392 if (err) 393 goto out_free; 394 } 395 396 skb_push(skb, ihl); 397 398 sg_init_table(sg, nfrags + sglists); 399 err = skb_to_sgvec_nomark(skb, sg, 0, skb->len); 400 if (unlikely(err < 0)) 401 goto out_free; 402 403 if (x->props.flags & XFRM_STATE_ESN) { 404 /* Attach seqhi sg right after packet payload */ 405 *seqhi = XFRM_SKB_CB(skb)->seq.input.hi; 406 sg_set_buf(seqhisg, seqhi, seqhi_len); 407 } 408 ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len); 409 ahash_request_set_callback(req, 0, ah_input_done, skb); 410 411 AH_SKB_CB(skb)->tmp = work_iph; 412 413 err = crypto_ahash_digest(req); 414 if (err) { 415 if (err == -EINPROGRESS) 416 goto out; 417 418 goto out_free; 419 } 420 421 err = crypto_memneq(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0; 422 if (err) 423 goto out_free; 424 425 skb->network_header += ah_hlen; 426 memcpy(skb_network_header(skb), work_iph, ihl); 427 __skb_pull(skb, ah_hlen + ihl); 428 if (x->props.mode == XFRM_MODE_TUNNEL) 429 skb_reset_transport_header(skb); 430 else 431 skb_set_transport_header(skb, -ihl); 432 433 err = nexthdr; 434 435 out_free: 436 kfree (work_iph); 437 out: 438 return err; 439 } 440 441 static int ah4_err(struct sk_buff *skb, u32 info) 442 { 443 struct net *net = dev_net(skb->dev); 444 const struct iphdr *iph = (const struct iphdr *)skb->data; 445 struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+(iph->ihl<<2)); 446 struct xfrm_state *x; 447 448 switch (icmp_hdr(skb)->type) { 449 case ICMP_DEST_UNREACH: 450 if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) 451 return 0; 452 case ICMP_REDIRECT: 453 break; 454 default: 455 return 0; 456 } 457 458 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr, 459 ah->spi, IPPROTO_AH, AF_INET); 460 if (!x) 461 return 0; 462 463 if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH) 464 ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_AH, 0); 465 else 466 ipv4_redirect(skb, net, 0, 0, IPPROTO_AH, 0); 467 xfrm_state_put(x); 468 469 return 0; 470 } 471 472 static int ah_init_state(struct xfrm_state *x) 473 { 474 struct ah_data *ahp = NULL; 475 struct xfrm_algo_desc *aalg_desc; 476 struct crypto_ahash *ahash; 477 478 if (!x->aalg) 479 goto error; 480 481 if (x->encap) 482 goto error; 483 484 ahp = kzalloc(sizeof(*ahp), GFP_KERNEL); 485 if (!ahp) 486 return -ENOMEM; 487 488 ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0); 489 if (IS_ERR(ahash)) 490 goto error; 491 492 ahp->ahash = ahash; 493 if (crypto_ahash_setkey(ahash, x->aalg->alg_key, 494 (x->aalg->alg_key_len + 7) / 8)) 495 goto error; 496 497 /* 498 * Lookup the algorithm description maintained by xfrm_algo, 499 * verify crypto transform properties, and store information 500 * we need for AH processing. This lookup cannot fail here 501 * after a successful crypto_alloc_ahash(). 502 */ 503 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 504 BUG_ON(!aalg_desc); 505 506 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 507 crypto_ahash_digestsize(ahash)) { 508 pr_info("%s: %s digestsize %u != %hu\n", 509 __func__, x->aalg->alg_name, 510 crypto_ahash_digestsize(ahash), 511 aalg_desc->uinfo.auth.icv_fullbits / 8); 512 goto error; 513 } 514 515 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 516 ahp->icv_trunc_len = x->aalg->alg_trunc_len/8; 517 518 if (x->props.flags & XFRM_STATE_ALIGN4) 519 x->props.header_len = XFRM_ALIGN4(sizeof(struct ip_auth_hdr) + 520 ahp->icv_trunc_len); 521 else 522 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + 523 ahp->icv_trunc_len); 524 if (x->props.mode == XFRM_MODE_TUNNEL) 525 x->props.header_len += sizeof(struct iphdr); 526 x->data = ahp; 527 528 return 0; 529 530 error: 531 if (ahp) { 532 crypto_free_ahash(ahp->ahash); 533 kfree(ahp); 534 } 535 return -EINVAL; 536 } 537 538 static void ah_destroy(struct xfrm_state *x) 539 { 540 struct ah_data *ahp = x->data; 541 542 if (!ahp) 543 return; 544 545 crypto_free_ahash(ahp->ahash); 546 kfree(ahp); 547 } 548 549 static int ah4_rcv_cb(struct sk_buff *skb, int err) 550 { 551 return 0; 552 } 553 554 static const struct xfrm_type ah_type = 555 { 556 .description = "AH4", 557 .owner = THIS_MODULE, 558 .proto = IPPROTO_AH, 559 .flags = XFRM_TYPE_REPLAY_PROT, 560 .init_state = ah_init_state, 561 .destructor = ah_destroy, 562 .input = ah_input, 563 .output = ah_output 564 }; 565 566 static struct xfrm4_protocol ah4_protocol = { 567 .handler = xfrm4_rcv, 568 .input_handler = xfrm_input, 569 .cb_handler = ah4_rcv_cb, 570 .err_handler = ah4_err, 571 .priority = 0, 572 }; 573 574 static int __init ah4_init(void) 575 { 576 if (xfrm_register_type(&ah_type, AF_INET) < 0) { 577 pr_info("%s: can't add xfrm type\n", __func__); 578 return -EAGAIN; 579 } 580 if (xfrm4_protocol_register(&ah4_protocol, IPPROTO_AH) < 0) { 581 pr_info("%s: can't add protocol\n", __func__); 582 xfrm_unregister_type(&ah_type, AF_INET); 583 return -EAGAIN; 584 } 585 return 0; 586 } 587 588 static void __exit ah4_fini(void) 589 { 590 if (xfrm4_protocol_deregister(&ah4_protocol, IPPROTO_AH) < 0) 591 pr_info("%s: can't remove protocol\n", __func__); 592 if (xfrm_unregister_type(&ah_type, AF_INET) < 0) 593 pr_info("%s: can't remove xfrm type\n", __func__); 594 } 595 596 module_init(ah4_init); 597 module_exit(ah4_fini); 598 MODULE_LICENSE("GPL"); 599 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH); 600