1#include <crypto/hash.h> 2#include <linux/err.h> 3#include <linux/module.h> 4#include <linux/slab.h> 5#include <net/ip.h> 6#include <net/xfrm.h> 7#include <net/ah.h> 8#include <linux/crypto.h> 9#include <linux/pfkeyv2.h> 10#include <linux/scatterlist.h> 11#include <net/icmp.h> 12#include <net/protocol.h> 13 14struct ah_skb_cb { 15 struct xfrm_skb_cb xfrm; 16 void *tmp; 17}; 18 19#define AH_SKB_CB(__skb) ((struct ah_skb_cb *)&((__skb)->cb[0])) 20 21static void *ah_alloc_tmp(struct crypto_ahash *ahash, int nfrags, 22 unsigned int size) 23{ 24 unsigned int len; 25 26 len = size + crypto_ahash_digestsize(ahash) + 27 (crypto_ahash_alignmask(ahash) & 28 ~(crypto_tfm_ctx_alignment() - 1)); 29 30 len = ALIGN(len, crypto_tfm_ctx_alignment()); 31 32 len += sizeof(struct ahash_request) + crypto_ahash_reqsize(ahash); 33 len = ALIGN(len, __alignof__(struct scatterlist)); 34 35 len += sizeof(struct scatterlist) * nfrags; 36 37 return kmalloc(len, GFP_ATOMIC); 38} 39 40static inline u8 *ah_tmp_auth(void *tmp, unsigned int offset) 41{ 42 return tmp + offset; 43} 44 45static inline u8 *ah_tmp_icv(struct crypto_ahash *ahash, void *tmp, 46 unsigned int offset) 47{ 48 return PTR_ALIGN((u8 *)tmp + offset, crypto_ahash_alignmask(ahash) + 1); 49} 50 51static inline struct ahash_request *ah_tmp_req(struct crypto_ahash *ahash, 52 u8 *icv) 53{ 54 struct ahash_request *req; 55 56 req = (void *)PTR_ALIGN(icv + crypto_ahash_digestsize(ahash), 57 crypto_tfm_ctx_alignment()); 58 59 ahash_request_set_tfm(req, ahash); 60 61 return req; 62} 63 64static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash, 65 struct ahash_request *req) 66{ 67 return (void *)ALIGN((unsigned long)(req + 1) + 68 crypto_ahash_reqsize(ahash), 69 __alignof__(struct scatterlist)); 70} 71 72/* Clear mutable options and find final destination to substitute 73 * into IP header for icv calculation. Options are already checked 74 * for validity, so paranoia is not required. */ 75 76static int ip_clear_mutable_options(struct iphdr *iph, __be32 *daddr) 77{ 78 unsigned char * optptr = (unsigned char*)(iph+1); 79 int l = iph->ihl*4 - sizeof(struct iphdr); 80 int optlen; 81 82 while (l > 0) { 83 switch (*optptr) { 84 case IPOPT_END: 85 return 0; 86 case IPOPT_NOOP: 87 l--; 88 optptr++; 89 continue; 90 } 91 optlen = optptr[1]; 92 if (optlen<2 || optlen>l) 93 return -EINVAL; 94 switch (*optptr) { 95 case IPOPT_SEC: 96 case 0x85: /* Some "Extended Security" crap. */ 97 case IPOPT_CIPSO: 98 case IPOPT_RA: 99 case 0x80|21: /* RFC1770 */ 100 break; 101 case IPOPT_LSRR: 102 case IPOPT_SSRR: 103 if (optlen < 6) 104 return -EINVAL; 105 memcpy(daddr, optptr+optlen-4, 4); 106 /* Fall through */ 107 default: 108 memset(optptr, 0, optlen); 109 } 110 l -= optlen; 111 optptr += optlen; 112 } 113 return 0; 114} 115 116static void ah_output_done(struct crypto_async_request *base, int err) 117{ 118 u8 *icv; 119 struct iphdr *iph; 120 struct sk_buff *skb = base->data; 121 struct xfrm_state *x = skb_dst(skb)->xfrm; 122 struct ah_data *ahp = x->data; 123 struct iphdr *top_iph = ip_hdr(skb); 124 struct ip_auth_hdr *ah = ip_auth_hdr(skb); 125 int ihl = ip_hdrlen(skb); 126 127 iph = AH_SKB_CB(skb)->tmp; 128 icv = ah_tmp_icv(ahp->ahash, iph, ihl); 129 memcpy(ah->auth_data, icv, ahp->icv_trunc_len); 130 131 top_iph->tos = iph->tos; 132 top_iph->ttl = iph->ttl; 133 top_iph->frag_off = iph->frag_off; 134 if (top_iph->ihl != 5) { 135 top_iph->daddr = iph->daddr; 136 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); 137 } 138 139 err = ah->nexthdr; 140 141 kfree(AH_SKB_CB(skb)->tmp); 142 xfrm_output_resume(skb, err); 143} 144 145static 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 ah->hdrlen = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2; 205 206 ah->reserved = 0; 207 ah->spi = x->id.spi; 208 ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output); 209 210 sg_init_table(sg, nfrags); 211 skb_to_sgvec(skb, sg, 0, skb->len); 212 213 ahash_request_set_crypt(req, sg, icv, skb->len); 214 ahash_request_set_callback(req, 0, ah_output_done, skb); 215 216 AH_SKB_CB(skb)->tmp = iph; 217 218 err = crypto_ahash_digest(req); 219 if (err) { 220 if (err == -EINPROGRESS) 221 goto out; 222 223 if (err == -EBUSY) 224 err = NET_XMIT_DROP; 225 goto out_free; 226 } 227 228 memcpy(ah->auth_data, icv, ahp->icv_trunc_len); 229 230 top_iph->tos = iph->tos; 231 top_iph->ttl = iph->ttl; 232 top_iph->frag_off = iph->frag_off; 233 if (top_iph->ihl != 5) { 234 top_iph->daddr = iph->daddr; 235 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); 236 } 237 238out_free: 239 kfree(iph); 240out: 241 return err; 242} 243 244static void ah_input_done(struct crypto_async_request *base, int err) 245{ 246 u8 *auth_data; 247 u8 *icv; 248 struct iphdr *work_iph; 249 struct sk_buff *skb = base->data; 250 struct xfrm_state *x = xfrm_input_state(skb); 251 struct ah_data *ahp = x->data; 252 struct ip_auth_hdr *ah = ip_auth_hdr(skb); 253 int ihl = ip_hdrlen(skb); 254 int ah_hlen = (ah->hdrlen + 2) << 2; 255 256 work_iph = AH_SKB_CB(skb)->tmp; 257 auth_data = ah_tmp_auth(work_iph, ihl); 258 icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len); 259 260 err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0; 261 if (err) 262 goto out; 263 264 skb->network_header += ah_hlen; 265 memcpy(skb_network_header(skb), work_iph, ihl); 266 __skb_pull(skb, ah_hlen + ihl); 267 skb_set_transport_header(skb, -ihl); 268 269 err = ah->nexthdr; 270out: 271 kfree(AH_SKB_CB(skb)->tmp); 272 xfrm_input_resume(skb, err); 273} 274 275static int ah_input(struct xfrm_state *x, struct sk_buff *skb) 276{ 277 int ah_hlen; 278 int ihl; 279 int nexthdr; 280 int nfrags; 281 u8 *auth_data; 282 u8 *icv; 283 struct sk_buff *trailer; 284 struct crypto_ahash *ahash; 285 struct ahash_request *req; 286 struct scatterlist *sg; 287 struct iphdr *iph, *work_iph; 288 struct ip_auth_hdr *ah; 289 struct ah_data *ahp; 290 int err = -ENOMEM; 291 292 if (!pskb_may_pull(skb, sizeof(*ah))) 293 goto out; 294 295 ah = (struct ip_auth_hdr *)skb->data; 296 ahp = x->data; 297 ahash = ahp->ahash; 298 299 nexthdr = ah->nexthdr; 300 ah_hlen = (ah->hdrlen + 2) << 2; 301 302 if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) && 303 ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len)) 304 goto out; 305 306 if (!pskb_may_pull(skb, ah_hlen)) 307 goto out; 308 309 /* We are going to _remove_ AH header to keep sockets happy, 310 * so... Later this can change. */ 311 if (skb_cloned(skb) && 312 pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) 313 goto out; 314 315 skb->ip_summed = CHECKSUM_NONE; 316 317 ah = (struct ip_auth_hdr *)skb->data; 318 iph = ip_hdr(skb); 319 ihl = ip_hdrlen(skb); 320 321 if ((err = skb_cow_data(skb, 0, &trailer)) < 0) 322 goto out; 323 nfrags = err; 324 325 work_iph = ah_alloc_tmp(ahash, nfrags, ihl + ahp->icv_trunc_len); 326 if (!work_iph) 327 goto out; 328 329 auth_data = ah_tmp_auth(work_iph, ihl); 330 icv = ah_tmp_icv(ahash, auth_data, ahp->icv_trunc_len); 331 req = ah_tmp_req(ahash, icv); 332 sg = ah_req_sg(ahash, req); 333 334 memcpy(work_iph, iph, ihl); 335 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len); 336 memset(ah->auth_data, 0, ahp->icv_trunc_len); 337 338 iph->ttl = 0; 339 iph->tos = 0; 340 iph->frag_off = 0; 341 iph->check = 0; 342 if (ihl > sizeof(*iph)) { 343 __be32 dummy; 344 err = ip_clear_mutable_options(iph, &dummy); 345 if (err) 346 goto out_free; 347 } 348 349 skb_push(skb, ihl); 350 351 sg_init_table(sg, nfrags); 352 skb_to_sgvec(skb, sg, 0, skb->len); 353 354 ahash_request_set_crypt(req, sg, icv, skb->len); 355 ahash_request_set_callback(req, 0, ah_input_done, skb); 356 357 AH_SKB_CB(skb)->tmp = work_iph; 358 359 err = crypto_ahash_digest(req); 360 if (err) { 361 if (err == -EINPROGRESS) 362 goto out; 363 364 if (err == -EBUSY) 365 err = NET_XMIT_DROP; 366 goto out_free; 367 } 368 369 err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0; 370 if (err) 371 goto out_free; 372 373 skb->network_header += ah_hlen; 374 memcpy(skb_network_header(skb), work_iph, ihl); 375 __skb_pull(skb, ah_hlen + ihl); 376 skb_set_transport_header(skb, -ihl); 377 378 err = nexthdr; 379 380out_free: 381 kfree (work_iph); 382out: 383 return err; 384} 385 386static void ah4_err(struct sk_buff *skb, u32 info) 387{ 388 struct net *net = dev_net(skb->dev); 389 struct iphdr *iph = (struct iphdr *)skb->data; 390 struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+(iph->ihl<<2)); 391 struct xfrm_state *x; 392 393 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH || 394 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) 395 return; 396 397 x = xfrm_state_lookup(net, skb->mark, (xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET); 398 if (!x) 399 return; 400 printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n", 401 ntohl(ah->spi), ntohl(iph->daddr)); 402 xfrm_state_put(x); 403} 404 405static int ah_init_state(struct xfrm_state *x) 406{ 407 struct ah_data *ahp = NULL; 408 struct xfrm_algo_desc *aalg_desc; 409 struct crypto_ahash *ahash; 410 411 if (!x->aalg) 412 goto error; 413 414 if (x->encap) 415 goto error; 416 417 ahp = kzalloc(sizeof(*ahp), GFP_KERNEL); 418 if (!ahp) 419 return -ENOMEM; 420 421 ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0); 422 if (IS_ERR(ahash)) 423 goto error; 424 425 ahp->ahash = ahash; 426 if (crypto_ahash_setkey(ahash, x->aalg->alg_key, 427 (x->aalg->alg_key_len + 7) / 8)) 428 goto error; 429 430 /* 431 * Lookup the algorithm description maintained by xfrm_algo, 432 * verify crypto transform properties, and store information 433 * we need for AH processing. This lookup cannot fail here 434 * after a successful crypto_alloc_ahash(). 435 */ 436 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 437 BUG_ON(!aalg_desc); 438 439 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 440 crypto_ahash_digestsize(ahash)) { 441 printk(KERN_INFO "AH: %s digestsize %u != %hu\n", 442 x->aalg->alg_name, crypto_ahash_digestsize(ahash), 443 aalg_desc->uinfo.auth.icv_fullbits/8); 444 goto error; 445 } 446 447 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 448 ahp->icv_trunc_len = x->aalg->alg_trunc_len/8; 449 450 BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN); 451 452 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + 453 ahp->icv_trunc_len); 454 if (x->props.mode == XFRM_MODE_TUNNEL) 455 x->props.header_len += sizeof(struct iphdr); 456 x->data = ahp; 457 458 return 0; 459 460error: 461 if (ahp) { 462 crypto_free_ahash(ahp->ahash); 463 kfree(ahp); 464 } 465 return -EINVAL; 466} 467 468static void ah_destroy(struct xfrm_state *x) 469{ 470 struct ah_data *ahp = x->data; 471 472 if (!ahp) 473 return; 474 475 crypto_free_ahash(ahp->ahash); 476 kfree(ahp); 477} 478 479 480static const struct xfrm_type ah_type = 481{ 482 .description = "AH4", 483 .owner = THIS_MODULE, 484 .proto = IPPROTO_AH, 485 .flags = XFRM_TYPE_REPLAY_PROT, 486 .init_state = ah_init_state, 487 .destructor = ah_destroy, 488 .input = ah_input, 489 .output = ah_output 490}; 491 492static const struct net_protocol ah4_protocol = { 493 .handler = xfrm4_rcv, 494 .err_handler = ah4_err, 495 .no_policy = 1, 496 .netns_ok = 1, 497}; 498 499static int __init ah4_init(void) 500{ 501 if (xfrm_register_type(&ah_type, AF_INET) < 0) { 502 printk(KERN_INFO "ip ah init: can't add xfrm type\n"); 503 return -EAGAIN; 504 } 505 if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) { 506 printk(KERN_INFO "ip ah init: can't add protocol\n"); 507 xfrm_unregister_type(&ah_type, AF_INET); 508 return -EAGAIN; 509 } 510 return 0; 511} 512 513static void __exit ah4_fini(void) 514{ 515 if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0) 516 printk(KERN_INFO "ip ah close: can't remove protocol\n"); 517 if (xfrm_unregister_type(&ah_type, AF_INET) < 0) 518 printk(KERN_INFO "ip ah close: can't remove xfrm type\n"); 519} 520 521module_init(ah4_init); 522module_exit(ah4_fini); 523MODULE_LICENSE("GPL"); 524MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH); 525