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