Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C)2002 USAGI/WIDE Project |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License as published by |
| 6 | * the Free Software Foundation; either version 2 of the License, or |
| 7 | * (at your option) any later version. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program; if not, write to the Free Software |
| 16 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 17 | * |
| 18 | * Authors |
| 19 | * |
| 20 | * Mitsuru KANDA @USAGI : IPv6 Support |
| 21 | * Kazunori MIYAZAWA @USAGI : |
| 22 | * Kunihiro Ishiguro <kunihiro@ipinfusion.com> |
| 23 | * |
| 24 | * This file is derived from net/ipv4/ah.c. |
| 25 | */ |
| 26 | |
| 27 | #include <linux/config.h> |
| 28 | #include <linux/module.h> |
| 29 | #include <net/ip.h> |
| 30 | #include <net/ah.h> |
| 31 | #include <linux/crypto.h> |
| 32 | #include <linux/pfkeyv2.h> |
| 33 | #include <linux/string.h> |
| 34 | #include <net/icmp.h> |
| 35 | #include <net/ipv6.h> |
| 36 | #include <net/xfrm.h> |
| 37 | #include <asm/scatterlist.h> |
| 38 | |
| 39 | static int zero_out_mutable_opts(struct ipv6_opt_hdr *opthdr) |
| 40 | { |
| 41 | u8 *opt = (u8 *)opthdr; |
| 42 | int len = ipv6_optlen(opthdr); |
| 43 | int off = 0; |
| 44 | int optlen = 0; |
| 45 | |
| 46 | off += 2; |
| 47 | len -= 2; |
| 48 | |
| 49 | while (len > 0) { |
| 50 | |
| 51 | switch (opt[off]) { |
| 52 | |
| 53 | case IPV6_TLV_PAD0: |
| 54 | optlen = 1; |
| 55 | break; |
| 56 | default: |
| 57 | if (len < 2) |
| 58 | goto bad; |
| 59 | optlen = opt[off+1]+2; |
| 60 | if (len < optlen) |
| 61 | goto bad; |
| 62 | if (opt[off] & 0x20) |
| 63 | memset(&opt[off+2], 0, opt[off+1]); |
| 64 | break; |
| 65 | } |
| 66 | |
| 67 | off += optlen; |
| 68 | len -= optlen; |
| 69 | } |
| 70 | if (len == 0) |
| 71 | return 1; |
| 72 | |
| 73 | bad: |
| 74 | return 0; |
| 75 | } |
| 76 | |
| 77 | /** |
| 78 | * ipv6_rearrange_rthdr - rearrange IPv6 routing header |
| 79 | * @iph: IPv6 header |
| 80 | * @rthdr: routing header |
| 81 | * |
| 82 | * Rearrange the destination address in @iph and the addresses in @rthdr |
| 83 | * so that they appear in the order they will at the final destination. |
| 84 | * See Appendix A2 of RFC 2402 for details. |
| 85 | */ |
| 86 | static void ipv6_rearrange_rthdr(struct ipv6hdr *iph, struct ipv6_rt_hdr *rthdr) |
| 87 | { |
| 88 | int segments, segments_left; |
| 89 | struct in6_addr *addrs; |
| 90 | struct in6_addr final_addr; |
| 91 | |
| 92 | segments_left = rthdr->segments_left; |
| 93 | if (segments_left == 0) |
| 94 | return; |
| 95 | rthdr->segments_left = 0; |
| 96 | |
| 97 | /* The value of rthdr->hdrlen has been verified either by the system |
| 98 | * call if it is locally generated, or by ipv6_rthdr_rcv() for incoming |
| 99 | * packets. So we can assume that it is even and that segments is |
| 100 | * greater than or equal to segments_left. |
| 101 | * |
| 102 | * For the same reason we can assume that this option is of type 0. |
| 103 | */ |
| 104 | segments = rthdr->hdrlen >> 1; |
| 105 | |
| 106 | addrs = ((struct rt0_hdr *)rthdr)->addr; |
| 107 | ipv6_addr_copy(&final_addr, addrs + segments - 1); |
| 108 | |
| 109 | addrs += segments - segments_left; |
| 110 | memmove(addrs + 1, addrs, (segments_left - 1) * sizeof(*addrs)); |
| 111 | |
| 112 | ipv6_addr_copy(addrs, &iph->daddr); |
| 113 | ipv6_addr_copy(&iph->daddr, &final_addr); |
| 114 | } |
| 115 | |
| 116 | static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len) |
| 117 | { |
| 118 | union { |
| 119 | struct ipv6hdr *iph; |
| 120 | struct ipv6_opt_hdr *opth; |
| 121 | struct ipv6_rt_hdr *rth; |
| 122 | char *raw; |
| 123 | } exthdr = { .iph = iph }; |
| 124 | char *end = exthdr.raw + len; |
| 125 | int nexthdr = iph->nexthdr; |
| 126 | |
| 127 | exthdr.iph++; |
| 128 | |
| 129 | while (exthdr.raw < end) { |
| 130 | switch (nexthdr) { |
| 131 | case NEXTHDR_HOP: |
| 132 | case NEXTHDR_DEST: |
| 133 | if (!zero_out_mutable_opts(exthdr.opth)) { |
| 134 | LIMIT_NETDEBUG(printk( |
| 135 | KERN_WARNING "overrun %sopts\n", |
| 136 | nexthdr == NEXTHDR_HOP ? |
| 137 | "hop" : "dest")); |
| 138 | return -EINVAL; |
| 139 | } |
| 140 | break; |
| 141 | |
| 142 | case NEXTHDR_ROUTING: |
| 143 | ipv6_rearrange_rthdr(iph, exthdr.rth); |
| 144 | break; |
| 145 | |
| 146 | default : |
| 147 | return 0; |
| 148 | } |
| 149 | |
| 150 | nexthdr = exthdr.opth->nexthdr; |
| 151 | exthdr.raw += ipv6_optlen(exthdr.opth); |
| 152 | } |
| 153 | |
| 154 | return 0; |
| 155 | } |
| 156 | |
| 157 | static int ah6_output(struct xfrm_state *x, struct sk_buff *skb) |
| 158 | { |
| 159 | int err; |
| 160 | int extlen; |
| 161 | struct ipv6hdr *top_iph; |
| 162 | struct ip_auth_hdr *ah; |
| 163 | struct ah_data *ahp; |
| 164 | u8 nexthdr; |
| 165 | char tmp_base[8]; |
| 166 | struct { |
| 167 | struct in6_addr daddr; |
| 168 | char hdrs[0]; |
| 169 | } *tmp_ext; |
| 170 | |
| 171 | top_iph = (struct ipv6hdr *)skb->data; |
| 172 | top_iph->payload_len = htons(skb->len - sizeof(*top_iph)); |
| 173 | |
| 174 | nexthdr = *skb->nh.raw; |
| 175 | *skb->nh.raw = IPPROTO_AH; |
| 176 | |
| 177 | /* When there are no extension headers, we only need to save the first |
| 178 | * 8 bytes of the base IP header. |
| 179 | */ |
| 180 | memcpy(tmp_base, top_iph, sizeof(tmp_base)); |
| 181 | |
| 182 | tmp_ext = NULL; |
| 183 | extlen = skb->h.raw - (unsigned char *)(top_iph + 1); |
| 184 | if (extlen) { |
| 185 | extlen += sizeof(*tmp_ext); |
| 186 | tmp_ext = kmalloc(extlen, GFP_ATOMIC); |
| 187 | if (!tmp_ext) { |
| 188 | err = -ENOMEM; |
| 189 | goto error; |
| 190 | } |
| 191 | memcpy(tmp_ext, &top_iph->daddr, extlen); |
| 192 | err = ipv6_clear_mutable_options(top_iph, |
| 193 | extlen - sizeof(*tmp_ext) + |
| 194 | sizeof(*top_iph)); |
| 195 | if (err) |
| 196 | goto error_free_iph; |
| 197 | } |
| 198 | |
| 199 | ah = (struct ip_auth_hdr *)skb->h.raw; |
| 200 | ah->nexthdr = nexthdr; |
| 201 | |
| 202 | top_iph->priority = 0; |
| 203 | top_iph->flow_lbl[0] = 0; |
| 204 | top_iph->flow_lbl[1] = 0; |
| 205 | top_iph->flow_lbl[2] = 0; |
| 206 | top_iph->hop_limit = 0; |
| 207 | |
| 208 | ahp = x->data; |
| 209 | ah->hdrlen = (XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + |
| 210 | ahp->icv_trunc_len) >> 2) - 2; |
| 211 | |
| 212 | ah->reserved = 0; |
| 213 | ah->spi = x->id.spi; |
| 214 | ah->seq_no = htonl(++x->replay.oseq); |
| 215 | ahp->icv(ahp, skb, ah->auth_data); |
| 216 | |
| 217 | err = 0; |
| 218 | |
| 219 | memcpy(top_iph, tmp_base, sizeof(tmp_base)); |
| 220 | if (tmp_ext) { |
| 221 | memcpy(&top_iph->daddr, tmp_ext, extlen); |
| 222 | error_free_iph: |
| 223 | kfree(tmp_ext); |
| 224 | } |
| 225 | |
| 226 | error: |
| 227 | return err; |
| 228 | } |
| 229 | |
| 230 | static int ah6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb) |
| 231 | { |
| 232 | /* |
| 233 | * Before process AH |
| 234 | * [IPv6][Ext1][Ext2][AH][Dest][Payload] |
| 235 | * |<-------------->| hdr_len |
| 236 | * |
| 237 | * To erase AH: |
| 238 | * Keeping copy of cleared headers. After AH processing, |
| 239 | * Moving the pointer of skb->nh.raw by using skb_pull as long as AH |
| 240 | * header length. Then copy back the copy as long as hdr_len |
| 241 | * If destination header following AH exists, copy it into after [Ext2]. |
| 242 | * |
| 243 | * |<>|[IPv6][Ext1][Ext2][Dest][Payload] |
| 244 | * There is offset of AH before IPv6 header after the process. |
| 245 | */ |
| 246 | |
| 247 | struct ipv6_auth_hdr *ah; |
| 248 | struct ah_data *ahp; |
| 249 | unsigned char *tmp_hdr = NULL; |
| 250 | u16 hdr_len; |
| 251 | u16 ah_hlen; |
| 252 | int nexthdr; |
| 253 | |
| 254 | if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr))) |
| 255 | goto out; |
| 256 | |
| 257 | /* We are going to _remove_ AH header to keep sockets happy, |
| 258 | * so... Later this can change. */ |
| 259 | if (skb_cloned(skb) && |
| 260 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) |
| 261 | goto out; |
| 262 | |
| 263 | hdr_len = skb->data - skb->nh.raw; |
| 264 | ah = (struct ipv6_auth_hdr*)skb->data; |
| 265 | ahp = x->data; |
| 266 | nexthdr = ah->nexthdr; |
| 267 | ah_hlen = (ah->hdrlen + 2) << 2; |
| 268 | |
| 269 | if (ah_hlen != XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_full_len) && |
| 270 | ah_hlen != XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_trunc_len)) |
| 271 | goto out; |
| 272 | |
| 273 | if (!pskb_may_pull(skb, ah_hlen)) |
| 274 | goto out; |
| 275 | |
| 276 | tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC); |
| 277 | if (!tmp_hdr) |
| 278 | goto out; |
| 279 | memcpy(tmp_hdr, skb->nh.raw, hdr_len); |
| 280 | if (ipv6_clear_mutable_options(skb->nh.ipv6h, hdr_len)) |
| 281 | goto out; |
| 282 | skb->nh.ipv6h->priority = 0; |
| 283 | skb->nh.ipv6h->flow_lbl[0] = 0; |
| 284 | skb->nh.ipv6h->flow_lbl[1] = 0; |
| 285 | skb->nh.ipv6h->flow_lbl[2] = 0; |
| 286 | skb->nh.ipv6h->hop_limit = 0; |
| 287 | |
| 288 | { |
| 289 | u8 auth_data[MAX_AH_AUTH_LEN]; |
| 290 | |
| 291 | memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len); |
| 292 | memset(ah->auth_data, 0, ahp->icv_trunc_len); |
| 293 | skb_push(skb, skb->data - skb->nh.raw); |
| 294 | ahp->icv(ahp, skb, ah->auth_data); |
| 295 | if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) { |
| 296 | LIMIT_NETDEBUG( |
| 297 | printk(KERN_WARNING "ipsec ah authentication error\n")); |
| 298 | x->stats.integrity_failed++; |
| 299 | goto free_out; |
| 300 | } |
| 301 | } |
| 302 | |
| 303 | skb->nh.raw = skb_pull(skb, ah_hlen); |
| 304 | memcpy(skb->nh.raw, tmp_hdr, hdr_len); |
| 305 | skb->nh.ipv6h->payload_len = htons(skb->len - sizeof(struct ipv6hdr)); |
| 306 | skb_pull(skb, hdr_len); |
| 307 | skb->h.raw = skb->data; |
| 308 | |
| 309 | |
| 310 | kfree(tmp_hdr); |
| 311 | |
| 312 | return nexthdr; |
| 313 | |
| 314 | free_out: |
| 315 | kfree(tmp_hdr); |
| 316 | out: |
| 317 | return -EINVAL; |
| 318 | } |
| 319 | |
| 320 | static void ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, |
| 321 | int type, int code, int offset, __u32 info) |
| 322 | { |
| 323 | struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; |
| 324 | struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+offset); |
| 325 | struct xfrm_state *x; |
| 326 | |
| 327 | if (type != ICMPV6_DEST_UNREACH && |
| 328 | type != ICMPV6_PKT_TOOBIG) |
| 329 | return; |
| 330 | |
| 331 | x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6); |
| 332 | if (!x) |
| 333 | return; |
| 334 | |
| 335 | NETDEBUG(printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/" |
| 336 | "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n", |
| 337 | ntohl(ah->spi), NIP6(iph->daddr))); |
| 338 | |
| 339 | xfrm_state_put(x); |
| 340 | } |
| 341 | |
| 342 | static int ah6_init_state(struct xfrm_state *x, void *args) |
| 343 | { |
| 344 | struct ah_data *ahp = NULL; |
| 345 | struct xfrm_algo_desc *aalg_desc; |
| 346 | |
| 347 | if (!x->aalg) |
| 348 | goto error; |
| 349 | |
| 350 | /* null auth can use a zero length key */ |
| 351 | if (x->aalg->alg_key_len > 512) |
| 352 | goto error; |
| 353 | |
| 354 | if (x->encap) |
| 355 | goto error; |
| 356 | |
| 357 | ahp = kmalloc(sizeof(*ahp), GFP_KERNEL); |
| 358 | if (ahp == NULL) |
| 359 | return -ENOMEM; |
| 360 | |
| 361 | memset(ahp, 0, sizeof(*ahp)); |
| 362 | |
| 363 | ahp->key = x->aalg->alg_key; |
| 364 | ahp->key_len = (x->aalg->alg_key_len+7)/8; |
| 365 | ahp->tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); |
| 366 | if (!ahp->tfm) |
| 367 | goto error; |
| 368 | ahp->icv = ah_hmac_digest; |
| 369 | |
| 370 | /* |
| 371 | * Lookup the algorithm description maintained by xfrm_algo, |
| 372 | * verify crypto transform properties, and store information |
| 373 | * we need for AH processing. This lookup cannot fail here |
| 374 | * after a successful crypto_alloc_tfm(). |
| 375 | */ |
| 376 | aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); |
| 377 | BUG_ON(!aalg_desc); |
| 378 | |
| 379 | if (aalg_desc->uinfo.auth.icv_fullbits/8 != |
| 380 | crypto_tfm_alg_digestsize(ahp->tfm)) { |
| 381 | printk(KERN_INFO "AH: %s digestsize %u != %hu\n", |
| 382 | x->aalg->alg_name, crypto_tfm_alg_digestsize(ahp->tfm), |
| 383 | aalg_desc->uinfo.auth.icv_fullbits/8); |
| 384 | goto error; |
| 385 | } |
| 386 | |
| 387 | ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; |
| 388 | ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; |
| 389 | |
| 390 | BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN); |
| 391 | |
| 392 | ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL); |
| 393 | if (!ahp->work_icv) |
| 394 | goto error; |
| 395 | |
| 396 | x->props.header_len = XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_trunc_len); |
| 397 | if (x->props.mode) |
| 398 | x->props.header_len += sizeof(struct ipv6hdr); |
| 399 | x->data = ahp; |
| 400 | |
| 401 | return 0; |
| 402 | |
| 403 | error: |
| 404 | if (ahp) { |
| 405 | if (ahp->work_icv) |
| 406 | kfree(ahp->work_icv); |
| 407 | if (ahp->tfm) |
| 408 | crypto_free_tfm(ahp->tfm); |
| 409 | kfree(ahp); |
| 410 | } |
| 411 | return -EINVAL; |
| 412 | } |
| 413 | |
| 414 | static void ah6_destroy(struct xfrm_state *x) |
| 415 | { |
| 416 | struct ah_data *ahp = x->data; |
| 417 | |
| 418 | if (!ahp) |
| 419 | return; |
| 420 | |
| 421 | if (ahp->work_icv) { |
| 422 | kfree(ahp->work_icv); |
| 423 | ahp->work_icv = NULL; |
| 424 | } |
| 425 | if (ahp->tfm) { |
| 426 | crypto_free_tfm(ahp->tfm); |
| 427 | ahp->tfm = NULL; |
| 428 | } |
| 429 | kfree(ahp); |
| 430 | } |
| 431 | |
| 432 | static struct xfrm_type ah6_type = |
| 433 | { |
| 434 | .description = "AH6", |
| 435 | .owner = THIS_MODULE, |
| 436 | .proto = IPPROTO_AH, |
| 437 | .init_state = ah6_init_state, |
| 438 | .destructor = ah6_destroy, |
| 439 | .input = ah6_input, |
| 440 | .output = ah6_output |
| 441 | }; |
| 442 | |
| 443 | static struct inet6_protocol ah6_protocol = { |
| 444 | .handler = xfrm6_rcv, |
| 445 | .err_handler = ah6_err, |
| 446 | .flags = INET6_PROTO_NOPOLICY, |
| 447 | }; |
| 448 | |
| 449 | static int __init ah6_init(void) |
| 450 | { |
| 451 | if (xfrm_register_type(&ah6_type, AF_INET6) < 0) { |
| 452 | printk(KERN_INFO "ipv6 ah init: can't add xfrm type\n"); |
| 453 | return -EAGAIN; |
| 454 | } |
| 455 | |
| 456 | if (inet6_add_protocol(&ah6_protocol, IPPROTO_AH) < 0) { |
| 457 | printk(KERN_INFO "ipv6 ah init: can't add protocol\n"); |
| 458 | xfrm_unregister_type(&ah6_type, AF_INET6); |
| 459 | return -EAGAIN; |
| 460 | } |
| 461 | |
| 462 | return 0; |
| 463 | } |
| 464 | |
| 465 | static void __exit ah6_fini(void) |
| 466 | { |
| 467 | if (inet6_del_protocol(&ah6_protocol, IPPROTO_AH) < 0) |
| 468 | printk(KERN_INFO "ipv6 ah close: can't remove protocol\n"); |
| 469 | |
| 470 | if (xfrm_unregister_type(&ah6_type, AF_INET6) < 0) |
| 471 | printk(KERN_INFO "ipv6 ah close: can't remove xfrm type\n"); |
| 472 | |
| 473 | } |
| 474 | |
| 475 | module_init(ah6_init); |
| 476 | module_exit(ah6_fini); |
| 477 | |
| 478 | MODULE_LICENSE("GPL"); |