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; 158 159 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 err = ah->nexthdr; 268 269 skb->network_header += ah_hlen; 270 memcpy(skb_network_header(skb), work_iph, ihl); 271 __skb_pull(skb, ah_hlen + ihl); 272 skb_set_transport_header(skb, -ihl); 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 goto out_free; 375 } 376 377 err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0; 378 if (err) 379 goto out_free; 380 381 skb->network_header += ah_hlen; 382 memcpy(skb_network_header(skb), work_iph, ihl); 383 __skb_pull(skb, ah_hlen + ihl); 384 skb_set_transport_header(skb, -ihl); 385 386 err = nexthdr; 387 388 out_free: 389 kfree (work_iph); 390 out: 391 return err; 392 } 393 394 static void ah4_err(struct sk_buff *skb, u32 info) 395 { 396 struct net *net = dev_net(skb->dev); 397 const struct iphdr *iph = (const struct iphdr *)skb->data; 398 struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+(iph->ihl<<2)); 399 struct xfrm_state *x; 400 401 switch (icmp_hdr(skb)->type) { 402 case ICMP_DEST_UNREACH: 403 if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) 404 return; 405 case ICMP_REDIRECT: 406 break; 407 default: 408 return; 409 } 410 411 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr, 412 ah->spi, IPPROTO_AH, AF_INET); 413 if (!x) 414 return; 415 416 if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH) 417 ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_AH, 0); 418 else 419 ipv4_redirect(skb, net, 0, 0, IPPROTO_AH, 0); 420 xfrm_state_put(x); 421 } 422 423 static int ah_init_state(struct xfrm_state *x) 424 { 425 struct ah_data *ahp = NULL; 426 struct xfrm_algo_desc *aalg_desc; 427 struct crypto_ahash *ahash; 428 429 if (!x->aalg) 430 goto error; 431 432 if (x->encap) 433 goto error; 434 435 ahp = kzalloc(sizeof(*ahp), GFP_KERNEL); 436 if (!ahp) 437 return -ENOMEM; 438 439 ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0); 440 if (IS_ERR(ahash)) 441 goto error; 442 443 ahp->ahash = ahash; 444 if (crypto_ahash_setkey(ahash, x->aalg->alg_key, 445 (x->aalg->alg_key_len + 7) / 8)) 446 goto error; 447 448 /* 449 * Lookup the algorithm description maintained by xfrm_algo, 450 * verify crypto transform properties, and store information 451 * we need for AH processing. This lookup cannot fail here 452 * after a successful crypto_alloc_ahash(). 453 */ 454 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 455 BUG_ON(!aalg_desc); 456 457 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 458 crypto_ahash_digestsize(ahash)) { 459 pr_info("%s: %s digestsize %u != %hu\n", 460 __func__, x->aalg->alg_name, 461 crypto_ahash_digestsize(ahash), 462 aalg_desc->uinfo.auth.icv_fullbits / 8); 463 goto error; 464 } 465 466 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 467 ahp->icv_trunc_len = x->aalg->alg_trunc_len/8; 468 469 BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN); 470 471 if (x->props.flags & XFRM_STATE_ALIGN4) 472 x->props.header_len = XFRM_ALIGN4(sizeof(struct ip_auth_hdr) + 473 ahp->icv_trunc_len); 474 else 475 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + 476 ahp->icv_trunc_len); 477 if (x->props.mode == XFRM_MODE_TUNNEL) 478 x->props.header_len += sizeof(struct iphdr); 479 x->data = ahp; 480 481 return 0; 482 483 error: 484 if (ahp) { 485 crypto_free_ahash(ahp->ahash); 486 kfree(ahp); 487 } 488 return -EINVAL; 489 } 490 491 static void ah_destroy(struct xfrm_state *x) 492 { 493 struct ah_data *ahp = x->data; 494 495 if (!ahp) 496 return; 497 498 crypto_free_ahash(ahp->ahash); 499 kfree(ahp); 500 } 501 502 503 static const struct xfrm_type ah_type = 504 { 505 .description = "AH4", 506 .owner = THIS_MODULE, 507 .proto = IPPROTO_AH, 508 .flags = XFRM_TYPE_REPLAY_PROT, 509 .init_state = ah_init_state, 510 .destructor = ah_destroy, 511 .input = ah_input, 512 .output = ah_output 513 }; 514 515 static const struct net_protocol ah4_protocol = { 516 .handler = xfrm4_rcv, 517 .err_handler = ah4_err, 518 .no_policy = 1, 519 .netns_ok = 1, 520 }; 521 522 static int __init ah4_init(void) 523 { 524 if (xfrm_register_type(&ah_type, AF_INET) < 0) { 525 pr_info("%s: can't add xfrm type\n", __func__); 526 return -EAGAIN; 527 } 528 if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) { 529 pr_info("%s: can't add protocol\n", __func__); 530 xfrm_unregister_type(&ah_type, AF_INET); 531 return -EAGAIN; 532 } 533 return 0; 534 } 535 536 static void __exit ah4_fini(void) 537 { 538 if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0) 539 pr_info("%s: can't remove protocol\n", __func__); 540 if (xfrm_unregister_type(&ah_type, AF_INET) < 0) 541 pr_info("%s: can't remove xfrm type\n", __func__); 542 } 543 544 module_init(ah4_init); 545 module_exit(ah4_fini); 546 MODULE_LICENSE("GPL"); 547 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH); 548