1 // SPDX-License-Identifier: GPL-2.0-only 2 #define pr_fmt(fmt) "IPsec: " fmt 3 4 #include <crypto/hash.h> 5 #include <crypto/utils.h> 6 #include <linux/err.h> 7 #include <linux/module.h> 8 #include <linux/slab.h> 9 #include <net/ip.h> 10 #include <net/xfrm.h> 11 #include <net/ah.h> 12 #include <linux/crypto.h> 13 #include <linux/pfkeyv2.h> 14 #include <linux/scatterlist.h> 15 #include <net/icmp.h> 16 #include <net/protocol.h> 17 18 struct ah_skb_cb { 19 struct xfrm_skb_cb xfrm; 20 void *tmp; 21 }; 22 23 #define AH_SKB_CB(__skb) ((struct ah_skb_cb *)&((__skb)->cb[0])) 24 25 static void *ah_alloc_tmp(struct crypto_ahash *ahash, int nfrags, 26 unsigned int size) 27 { 28 unsigned int len; 29 30 len = size + crypto_ahash_digestsize(ahash); 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(void *tmp, unsigned int offset) 48 { 49 return tmp + offset; 50 } 51 52 static inline struct ahash_request *ah_tmp_req(struct crypto_ahash *ahash, 53 u8 *icv) 54 { 55 struct ahash_request *req; 56 57 req = (void *)PTR_ALIGN(icv + crypto_ahash_digestsize(ahash), 58 crypto_tfm_ctx_alignment()); 59 60 ahash_request_set_tfm(req, ahash); 61 62 return req; 63 } 64 65 static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash, 66 struct ahash_request *req) 67 { 68 return (void *)ALIGN((unsigned long)(req + 1) + 69 crypto_ahash_reqsize(ahash), 70 __alignof__(struct scatterlist)); 71 } 72 73 /* Clear mutable options and find final destination to substitute 74 * into IP header for icv calculation. Options are already checked 75 * for validity, so paranoia is not required. */ 76 77 static int ip_clear_mutable_options(const struct iphdr *iph, __be32 *daddr) 78 { 79 unsigned char *optptr = (unsigned char *)(iph+1); 80 int l = iph->ihl*4 - sizeof(struct iphdr); 81 int optlen; 82 83 while (l > 0) { 84 switch (*optptr) { 85 case IPOPT_END: 86 return 0; 87 case IPOPT_NOOP: 88 l--; 89 optptr++; 90 continue; 91 } 92 optlen = optptr[1]; 93 if (optlen<2 || optlen>l) 94 return -EINVAL; 95 switch (*optptr) { 96 case IPOPT_SEC: 97 case 0x85: /* Some "Extended Security" crap. */ 98 case IPOPT_CIPSO: 99 case IPOPT_RA: 100 case 0x80|21: /* RFC1770 */ 101 break; 102 case IPOPT_LSRR: 103 case IPOPT_SSRR: 104 if (optlen < 6) 105 return -EINVAL; 106 memcpy(daddr, optptr+optlen-4, 4); 107 fallthrough; 108 default: 109 memset(optptr, 0, optlen); 110 } 111 l -= optlen; 112 optptr += optlen; 113 } 114 return 0; 115 } 116 117 static void ah_output_done(void *data, int err) 118 { 119 u8 *icv; 120 struct iphdr *iph; 121 struct sk_buff *skb = data; 122 struct xfrm_state *x = skb_dst(skb)->xfrm; 123 struct ah_data *ahp = x->data; 124 struct iphdr *top_iph = ip_hdr(skb); 125 struct ip_auth_hdr *ah = ip_auth_hdr(skb); 126 int ihl = ip_hdrlen(skb); 127 128 iph = AH_SKB_CB(skb)->tmp; 129 icv = ah_tmp_icv(iph, ihl); 130 memcpy(ah->auth_data, icv, ahp->icv_trunc_len); 131 132 top_iph->tos = iph->tos; 133 top_iph->ttl = iph->ttl; 134 top_iph->frag_off = iph->frag_off; 135 if (top_iph->ihl != 5) { 136 top_iph->daddr = iph->daddr; 137 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); 138 } 139 140 kfree(AH_SKB_CB(skb)->tmp); 141 xfrm_output_resume(skb->sk, skb, err); 142 } 143 144 static int ah_output(struct xfrm_state *x, struct sk_buff *skb) 145 { 146 int err; 147 int nfrags; 148 int ihl; 149 u8 *icv; 150 struct sk_buff *trailer; 151 struct crypto_ahash *ahash; 152 struct ahash_request *req; 153 struct scatterlist *sg; 154 struct iphdr *iph, *top_iph; 155 struct ip_auth_hdr *ah; 156 struct ah_data *ahp; 157 int seqhi_len = 0; 158 __be32 *seqhi; 159 int sglists = 0; 160 struct scatterlist *seqhisg; 161 162 ahp = x->data; 163 ahash = ahp->ahash; 164 165 if ((err = skb_cow_data(skb, 0, &trailer)) < 0) 166 goto out; 167 nfrags = err; 168 169 skb_push(skb, -skb_network_offset(skb)); 170 ah = ip_auth_hdr(skb); 171 ihl = ip_hdrlen(skb); 172 173 if (x->props.flags & XFRM_STATE_ESN) { 174 sglists = 1; 175 seqhi_len = sizeof(*seqhi); 176 } 177 err = -ENOMEM; 178 iph = ah_alloc_tmp(ahash, nfrags + sglists, ihl + seqhi_len); 179 if (!iph) 180 goto out; 181 seqhi = (__be32 *)((char *)iph + ihl); 182 icv = ah_tmp_icv(seqhi, seqhi_len); 183 req = ah_tmp_req(ahash, icv); 184 sg = ah_req_sg(ahash, req); 185 seqhisg = sg + nfrags; 186 187 memset(ah->auth_data, 0, ahp->icv_trunc_len); 188 189 top_iph = ip_hdr(skb); 190 191 iph->tos = top_iph->tos; 192 iph->ttl = top_iph->ttl; 193 iph->frag_off = top_iph->frag_off; 194 195 if (top_iph->ihl != 5) { 196 iph->daddr = top_iph->daddr; 197 memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); 198 err = ip_clear_mutable_options(top_iph, &top_iph->daddr); 199 if (err) 200 goto out_free; 201 } 202 203 ah->nexthdr = *skb_mac_header(skb); 204 *skb_mac_header(skb) = IPPROTO_AH; 205 206 top_iph->tos = 0; 207 top_iph->tot_len = htons(skb->len); 208 top_iph->frag_off = 0; 209 top_iph->ttl = 0; 210 top_iph->check = 0; 211 212 if (x->props.flags & XFRM_STATE_ALIGN4) 213 ah->hdrlen = (XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2; 214 else 215 ah->hdrlen = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2; 216 217 ah->reserved = 0; 218 ah->spi = x->id.spi; 219 ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low); 220 221 sg_init_table(sg, nfrags + sglists); 222 err = skb_to_sgvec_nomark(skb, sg, 0, skb->len); 223 if (unlikely(err < 0)) 224 goto out_free; 225 226 if (x->props.flags & XFRM_STATE_ESN) { 227 /* Attach seqhi sg right after packet payload */ 228 *seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi); 229 sg_set_buf(seqhisg, seqhi, seqhi_len); 230 } 231 ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len); 232 ahash_request_set_callback(req, 0, ah_output_done, skb); 233 234 AH_SKB_CB(skb)->tmp = iph; 235 236 err = crypto_ahash_digest(req); 237 if (err) { 238 if (err == -EINPROGRESS) 239 goto out; 240 241 if (err == -ENOSPC) 242 err = NET_XMIT_DROP; 243 goto out_free; 244 } 245 246 memcpy(ah->auth_data, icv, ahp->icv_trunc_len); 247 248 top_iph->tos = iph->tos; 249 top_iph->ttl = iph->ttl; 250 top_iph->frag_off = iph->frag_off; 251 if (top_iph->ihl != 5) { 252 top_iph->daddr = iph->daddr; 253 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); 254 } 255 256 out_free: 257 kfree(iph); 258 out: 259 return err; 260 } 261 262 static void ah_input_done(void *data, int err) 263 { 264 u8 *auth_data; 265 u8 *icv; 266 struct iphdr *work_iph; 267 struct sk_buff *skb = data; 268 struct xfrm_state *x = xfrm_input_state(skb); 269 struct ah_data *ahp = x->data; 270 struct ip_auth_hdr *ah = ip_auth_hdr(skb); 271 int ihl = ip_hdrlen(skb); 272 int ah_hlen = (ah->hdrlen + 2) << 2; 273 274 if (err) 275 goto out; 276 277 work_iph = AH_SKB_CB(skb)->tmp; 278 auth_data = ah_tmp_auth(work_iph, ihl); 279 icv = ah_tmp_icv(auth_data, ahp->icv_trunc_len); 280 281 err = crypto_memneq(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0; 282 if (err) 283 goto out; 284 285 err = ah->nexthdr; 286 287 skb->network_header += ah_hlen; 288 memcpy(skb_network_header(skb), work_iph, ihl); 289 __skb_pull(skb, ah_hlen + ihl); 290 291 if (x->props.mode == XFRM_MODE_TUNNEL) 292 skb_reset_transport_header(skb); 293 else 294 skb_set_transport_header(skb, -ihl); 295 out: 296 kfree(AH_SKB_CB(skb)->tmp); 297 xfrm_input_resume(skb, err); 298 } 299 300 static int ah_input(struct xfrm_state *x, struct sk_buff *skb) 301 { 302 int ah_hlen; 303 int ihl; 304 int nexthdr; 305 int nfrags; 306 u8 *auth_data; 307 u8 *icv; 308 struct sk_buff *trailer; 309 struct crypto_ahash *ahash; 310 struct ahash_request *req; 311 struct scatterlist *sg; 312 struct iphdr *iph, *work_iph; 313 struct ip_auth_hdr *ah; 314 struct ah_data *ahp; 315 int err = -ENOMEM; 316 int seqhi_len = 0; 317 __be32 *seqhi; 318 int sglists = 0; 319 struct scatterlist *seqhisg; 320 321 if (!pskb_may_pull(skb, sizeof(*ah))) 322 goto out; 323 324 ah = (struct ip_auth_hdr *)skb->data; 325 ahp = x->data; 326 ahash = ahp->ahash; 327 328 nexthdr = ah->nexthdr; 329 ah_hlen = (ah->hdrlen + 2) << 2; 330 331 if (x->props.flags & XFRM_STATE_ALIGN4) { 332 if (ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_full_len) && 333 ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len)) 334 goto out; 335 } else { 336 if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) && 337 ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len)) 338 goto out; 339 } 340 341 if (!pskb_may_pull(skb, ah_hlen)) 342 goto out; 343 344 /* We are going to _remove_ AH header to keep sockets happy, 345 * so... Later this can change. */ 346 if (skb_unclone(skb, GFP_ATOMIC)) 347 goto out; 348 349 skb->ip_summed = CHECKSUM_NONE; 350 351 352 if ((err = skb_cow_data(skb, 0, &trailer)) < 0) 353 goto out; 354 nfrags = err; 355 356 ah = (struct ip_auth_hdr *)skb->data; 357 iph = ip_hdr(skb); 358 ihl = ip_hdrlen(skb); 359 360 if (x->props.flags & XFRM_STATE_ESN) { 361 sglists = 1; 362 seqhi_len = sizeof(*seqhi); 363 } 364 365 work_iph = ah_alloc_tmp(ahash, nfrags + sglists, ihl + 366 ahp->icv_trunc_len + seqhi_len); 367 if (!work_iph) { 368 err = -ENOMEM; 369 goto out; 370 } 371 372 seqhi = (__be32 *)((char *)work_iph + ihl); 373 auth_data = ah_tmp_auth(seqhi, seqhi_len); 374 icv = ah_tmp_icv(auth_data, ahp->icv_trunc_len); 375 req = ah_tmp_req(ahash, icv); 376 sg = ah_req_sg(ahash, req); 377 seqhisg = sg + nfrags; 378 379 memcpy(work_iph, iph, ihl); 380 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len); 381 memset(ah->auth_data, 0, ahp->icv_trunc_len); 382 383 iph->ttl = 0; 384 iph->tos = 0; 385 iph->frag_off = 0; 386 iph->check = 0; 387 if (ihl > sizeof(*iph)) { 388 __be32 dummy; 389 err = ip_clear_mutable_options(iph, &dummy); 390 if (err) 391 goto out_free; 392 } 393 394 skb_push(skb, ihl); 395 396 sg_init_table(sg, nfrags + sglists); 397 err = skb_to_sgvec_nomark(skb, sg, 0, skb->len); 398 if (unlikely(err < 0)) 399 goto out_free; 400 401 if (x->props.flags & XFRM_STATE_ESN) { 402 /* Attach seqhi sg right after packet payload */ 403 *seqhi = XFRM_SKB_CB(skb)->seq.input.hi; 404 sg_set_buf(seqhisg, seqhi, seqhi_len); 405 } 406 ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len); 407 ahash_request_set_callback(req, 0, ah_input_done, skb); 408 409 AH_SKB_CB(skb)->tmp = work_iph; 410 411 err = crypto_ahash_digest(req); 412 if (err) { 413 if (err == -EINPROGRESS) 414 goto out; 415 416 goto out_free; 417 } 418 419 err = crypto_memneq(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0; 420 if (err) 421 goto out_free; 422 423 skb->network_header += ah_hlen; 424 memcpy(skb_network_header(skb), work_iph, ihl); 425 __skb_pull(skb, ah_hlen + ihl); 426 if (x->props.mode == XFRM_MODE_TUNNEL) 427 skb_reset_transport_header(skb); 428 else 429 skb_set_transport_header(skb, -ihl); 430 431 err = nexthdr; 432 433 out_free: 434 kfree (work_iph); 435 out: 436 return err; 437 } 438 439 static int ah4_err(struct sk_buff *skb, u32 info) 440 { 441 struct net *net = dev_net(skb->dev); 442 const struct iphdr *iph = (const struct iphdr *)skb->data; 443 struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+(iph->ihl<<2)); 444 struct xfrm_state *x; 445 446 switch (icmp_hdr(skb)->type) { 447 case ICMP_DEST_UNREACH: 448 if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) 449 return 0; 450 break; 451 case ICMP_REDIRECT: 452 break; 453 default: 454 return 0; 455 } 456 457 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr, 458 ah->spi, IPPROTO_AH, AF_INET); 459 if (!x) 460 return 0; 461 462 if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH) 463 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_AH); 464 else 465 ipv4_redirect(skb, net, 0, IPPROTO_AH); 466 xfrm_state_put(x); 467 468 return 0; 469 } 470 471 static int ah_init_state(struct xfrm_state *x, struct netlink_ext_ack *extack) 472 { 473 struct ah_data *ahp = NULL; 474 struct xfrm_algo_desc *aalg_desc; 475 struct crypto_ahash *ahash; 476 477 if (!x->aalg) { 478 NL_SET_ERR_MSG(extack, "AH requires a state with an AUTH algorithm"); 479 goto error; 480 } 481 482 if (x->encap) { 483 NL_SET_ERR_MSG(extack, "AH is not compatible with encapsulation"); 484 goto error; 485 } 486 487 ahp = kzalloc(sizeof(*ahp), GFP_KERNEL); 488 if (!ahp) 489 return -ENOMEM; 490 491 ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0); 492 if (IS_ERR(ahash)) { 493 NL_SET_ERR_MSG(extack, "Kernel was unable to initialize cryptographic operations"); 494 goto error; 495 } 496 497 ahp->ahash = ahash; 498 if (crypto_ahash_setkey(ahash, x->aalg->alg_key, 499 (x->aalg->alg_key_len + 7) / 8)) { 500 NL_SET_ERR_MSG(extack, "Kernel was unable to initialize cryptographic operations"); 501 goto error; 502 } 503 504 /* 505 * Lookup the algorithm description maintained by xfrm_algo, 506 * verify crypto transform properties, and store information 507 * we need for AH processing. This lookup cannot fail here 508 * after a successful crypto_alloc_ahash(). 509 */ 510 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 511 BUG_ON(!aalg_desc); 512 513 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 514 crypto_ahash_digestsize(ahash)) { 515 NL_SET_ERR_MSG(extack, "Kernel was unable to initialize cryptographic operations"); 516 goto error; 517 } 518 519 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 520 ahp->icv_trunc_len = x->aalg->alg_trunc_len/8; 521 522 if (x->props.flags & XFRM_STATE_ALIGN4) 523 x->props.header_len = XFRM_ALIGN4(sizeof(struct ip_auth_hdr) + 524 ahp->icv_trunc_len); 525 else 526 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + 527 ahp->icv_trunc_len); 528 if (x->props.mode == XFRM_MODE_TUNNEL) 529 x->props.header_len += sizeof(struct iphdr); 530 x->data = ahp; 531 532 return 0; 533 534 error: 535 if (ahp) { 536 crypto_free_ahash(ahp->ahash); 537 kfree(ahp); 538 } 539 return -EINVAL; 540 } 541 542 static void ah_destroy(struct xfrm_state *x) 543 { 544 struct ah_data *ahp = x->data; 545 546 if (!ahp) 547 return; 548 549 crypto_free_ahash(ahp->ahash); 550 kfree(ahp); 551 } 552 553 static int ah4_rcv_cb(struct sk_buff *skb, int err) 554 { 555 return 0; 556 } 557 558 static const struct xfrm_type ah_type = 559 { 560 .owner = THIS_MODULE, 561 .proto = IPPROTO_AH, 562 .flags = XFRM_TYPE_REPLAY_PROT, 563 .init_state = ah_init_state, 564 .destructor = ah_destroy, 565 .input = ah_input, 566 .output = ah_output 567 }; 568 569 static struct xfrm4_protocol ah4_protocol = { 570 .handler = xfrm4_rcv, 571 .input_handler = xfrm_input, 572 .cb_handler = ah4_rcv_cb, 573 .err_handler = ah4_err, 574 .priority = 0, 575 }; 576 577 static int __init ah4_init(void) 578 { 579 if (xfrm_register_type(&ah_type, AF_INET) < 0) { 580 pr_info("%s: can't add xfrm type\n", __func__); 581 return -EAGAIN; 582 } 583 if (xfrm4_protocol_register(&ah4_protocol, IPPROTO_AH) < 0) { 584 pr_info("%s: can't add protocol\n", __func__); 585 xfrm_unregister_type(&ah_type, AF_INET); 586 return -EAGAIN; 587 } 588 return 0; 589 } 590 591 static void __exit ah4_fini(void) 592 { 593 if (xfrm4_protocol_deregister(&ah4_protocol, IPPROTO_AH) < 0) 594 pr_info("%s: can't remove protocol\n", __func__); 595 xfrm_unregister_type(&ah_type, AF_INET); 596 } 597 598 module_init(ah4_init); 599 module_exit(ah4_fini); 600 MODULE_DESCRIPTION("IPv4 AH transformation library"); 601 MODULE_LICENSE("GPL"); 602 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH); 603