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/module.h>
28 #include <net/ip.h>
29 #include <net/ah.h>
30 #include <linux/crypto.h>
31 #include <linux/pfkeyv2.h>
32 #include <linux/spinlock.h>
33 #include <linux/string.h>
34 #include <net/icmp.h>
35 #include <net/ipv6.h>
36 #include <net/protocol.h>
37 #include <net/xfrm.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 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
78 /**
79 * ipv6_rearrange_destopt - rearrange IPv6 destination options header
80 * @iph: IPv6 header
81 * @destopt: destionation options header
82 */
83 static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt)
84 {
85 u8 *opt = (u8 *)destopt;
86 int len = ipv6_optlen(destopt);
87 int off = 0;
88 int optlen = 0;
89
90 off += 2;
91 len -= 2;
92
93 while (len > 0) {
94
95 switch (opt[off]) {
96
97 case IPV6_TLV_PAD0:
98 optlen = 1;
99 break;
100 default:
101 if (len < 2)
102 goto bad;
103 optlen = opt[off+1]+2;
104 if (len < optlen)
105 goto bad;
106
107 /* Rearrange the source address in @iph and the
108 * addresses in home address option for final source.
109 * See 11.3.2 of RFC 3775 for details.
110 */
111 if (opt[off] == IPV6_TLV_HAO) {
112 struct in6_addr final_addr;
113 struct ipv6_destopt_hao *hao;
114
115 hao = (struct ipv6_destopt_hao *)&opt[off];
116 if (hao->length != sizeof(hao->addr)) {
117 if (net_ratelimit())
118 printk(KERN_WARNING "destopt hao: invalid header length: %u\n", hao->length);
119 goto bad;
120 }
121 ipv6_addr_copy(&final_addr, &hao->addr);
122 ipv6_addr_copy(&hao->addr, &iph->saddr);
123 ipv6_addr_copy(&iph->saddr, &final_addr);
124 }
125 break;
126 }
127
128 off += optlen;
129 len -= optlen;
130 }
131 /* Note: ok if len == 0 */
132 bad:
133 return;
134 }
135 #else
136 static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt) {}
137 #endif
138
139 /**
140 * ipv6_rearrange_rthdr - rearrange IPv6 routing header
141 * @iph: IPv6 header
142 * @rthdr: routing header
143 *
144 * Rearrange the destination address in @iph and the addresses in @rthdr
145 * so that they appear in the order they will at the final destination.
146 * See Appendix A2 of RFC 2402 for details.
147 */
148 static void ipv6_rearrange_rthdr(struct ipv6hdr *iph, struct ipv6_rt_hdr *rthdr)
149 {
150 int segments, segments_left;
151 struct in6_addr *addrs;
152 struct in6_addr final_addr;
153
154 segments_left = rthdr->segments_left;
155 if (segments_left == 0)
156 return;
157 rthdr->segments_left = 0;
158
159 /* The value of rthdr->hdrlen has been verified either by the system
160 * call if it is locally generated, or by ipv6_rthdr_rcv() for incoming
161 * packets. So we can assume that it is even and that segments is
162 * greater than or equal to segments_left.
163 *
164 * For the same reason we can assume that this option is of type 0.
165 */
166 segments = rthdr->hdrlen >> 1;
167
168 addrs = ((struct rt0_hdr *)rthdr)->addr;
169 ipv6_addr_copy(&final_addr, addrs + segments - 1);
170
171 addrs += segments - segments_left;
172 memmove(addrs + 1, addrs, (segments_left - 1) * sizeof(*addrs));
173
174 ipv6_addr_copy(addrs, &iph->daddr);
175 ipv6_addr_copy(&iph->daddr, &final_addr);
176 }
177
178 static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len, int dir)
179 {
180 union {
181 struct ipv6hdr *iph;
182 struct ipv6_opt_hdr *opth;
183 struct ipv6_rt_hdr *rth;
184 char *raw;
185 } exthdr = { .iph = iph };
186 char *end = exthdr.raw + len;
187 int nexthdr = iph->nexthdr;
188
189 exthdr.iph++;
190
191 while (exthdr.raw < end) {
192 switch (nexthdr) {
193 case NEXTHDR_DEST:
194 if (dir == XFRM_POLICY_OUT)
195 ipv6_rearrange_destopt(iph, exthdr.opth);
196 case NEXTHDR_HOP:
197 if (!zero_out_mutable_opts(exthdr.opth)) {
198 LIMIT_NETDEBUG(
199 KERN_WARNING "overrun %sopts\n",
200 nexthdr == NEXTHDR_HOP ?
201 "hop" : "dest");
202 return -EINVAL;
203 }
204 break;
205
206 case NEXTHDR_ROUTING:
207 ipv6_rearrange_rthdr(iph, exthdr.rth);
208 break;
209
210 default :
211 return 0;
212 }
213
214 nexthdr = exthdr.opth->nexthdr;
215 exthdr.raw += ipv6_optlen(exthdr.opth);
216 }
217
218 return 0;
219 }
220
221 static int ah6_output(struct xfrm_state *x, struct sk_buff *skb)
222 {
223 int err;
224 int extlen;
225 struct ipv6hdr *top_iph;
226 struct ip_auth_hdr *ah;
227 struct ah_data *ahp;
228 u8 nexthdr;
229 char tmp_base[8];
230 struct {
231 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
232 struct in6_addr saddr;
233 #endif
234 struct in6_addr daddr;
235 char hdrs[0];
236 } *tmp_ext;
237
238 skb_push(skb, -skb_network_offset(skb));
239 top_iph = ipv6_hdr(skb);
240 top_iph->payload_len = htons(skb->len - sizeof(*top_iph));
241
242 nexthdr = *skb_mac_header(skb);
243 *skb_mac_header(skb) = IPPROTO_AH;
244
245 /* When there are no extension headers, we only need to save the first
246 * 8 bytes of the base IP header.
247 */
248 memcpy(tmp_base, top_iph, sizeof(tmp_base));
249
250 tmp_ext = NULL;
251 extlen = skb_transport_offset(skb) - sizeof(struct ipv6hdr);
252 if (extlen) {
253 extlen += sizeof(*tmp_ext);
254 tmp_ext = kmalloc(extlen, GFP_ATOMIC);
255 if (!tmp_ext) {
256 err = -ENOMEM;
257 goto error;
258 }
259 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
260 memcpy(tmp_ext, &top_iph->saddr, extlen);
261 #else
262 memcpy(tmp_ext, &top_iph->daddr, extlen);
263 #endif
264 err = ipv6_clear_mutable_options(top_iph,
265 extlen - sizeof(*tmp_ext) +
266 sizeof(*top_iph),
267 XFRM_POLICY_OUT);
268 if (err)
269 goto error_free_iph;
270 }
271
272 ah = ip_auth_hdr(skb);
273 ah->nexthdr = nexthdr;
274
275 top_iph->priority = 0;
276 top_iph->flow_lbl[0] = 0;
277 top_iph->flow_lbl[1] = 0;
278 top_iph->flow_lbl[2] = 0;
279 top_iph->hop_limit = 0;
280
281 ahp = x->data;
282 ah->hdrlen = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
283
284 ah->reserved = 0;
285 ah->spi = x->id.spi;
286 ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output);
287
288 spin_lock_bh(&x->lock);
289 err = ah_mac_digest(ahp, skb, ah->auth_data);
290 memcpy(ah->auth_data, ahp->work_icv, ahp->icv_trunc_len);
291 spin_unlock_bh(&x->lock);
292
293 if (err)
294 goto error_free_iph;
295
296 memcpy(top_iph, tmp_base, sizeof(tmp_base));
297 if (tmp_ext) {
298 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
299 memcpy(&top_iph->saddr, tmp_ext, extlen);
300 #else
301 memcpy(&top_iph->daddr, tmp_ext, extlen);
302 #endif
303 error_free_iph:
304 kfree(tmp_ext);
305 }
306
307 error:
308 return err;
309 }
310
311 static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
312 {
313 /*
314 * Before process AH
315 * [IPv6][Ext1][Ext2][AH][Dest][Payload]
316 * |<-------------->| hdr_len
317 *
318 * To erase AH:
319 * Keeping copy of cleared headers. After AH processing,
320 * Moving the pointer of skb->network_header by using skb_pull as long
321 * as AH header length. Then copy back the copy as long as hdr_len
322 * If destination header following AH exists, copy it into after [Ext2].
323 *
324 * |<>|[IPv6][Ext1][Ext2][Dest][Payload]
325 * There is offset of AH before IPv6 header after the process.
326 */
327
328 struct ip_auth_hdr *ah;
329 struct ipv6hdr *ip6h;
330 struct ah_data *ahp;
331 unsigned char *tmp_hdr = NULL;
332 u16 hdr_len;
333 u16 ah_hlen;
334 int nexthdr;
335 int err = -EINVAL;
336
337 if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
338 goto out;
339
340 /* We are going to _remove_ AH header to keep sockets happy,
341 * so... Later this can change. */
342 if (skb_cloned(skb) &&
343 pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
344 goto out;
345
346 skb->ip_summed = CHECKSUM_NONE;
347
348 hdr_len = skb->data - skb_network_header(skb);
349 ah = (struct ip_auth_hdr *)skb->data;
350 ahp = x->data;
351 nexthdr = ah->nexthdr;
352 ah_hlen = (ah->hdrlen + 2) << 2;
353
354 if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
355 ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
356 goto out;
357
358 if (!pskb_may_pull(skb, ah_hlen))
359 goto out;
360
361 tmp_hdr = kmemdup(skb_network_header(skb), hdr_len, GFP_ATOMIC);
362 if (!tmp_hdr)
363 goto out;
364 ip6h = ipv6_hdr(skb);
365 if (ipv6_clear_mutable_options(ip6h, hdr_len, XFRM_POLICY_IN))
366 goto free_out;
367 ip6h->priority = 0;
368 ip6h->flow_lbl[0] = 0;
369 ip6h->flow_lbl[1] = 0;
370 ip6h->flow_lbl[2] = 0;
371 ip6h->hop_limit = 0;
372
373 spin_lock(&x->lock);
374 {
375 u8 auth_data[MAX_AH_AUTH_LEN];
376
377 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
378 memset(ah->auth_data, 0, ahp->icv_trunc_len);
379 skb_push(skb, hdr_len);
380 err = ah_mac_digest(ahp, skb, ah->auth_data);
381 if (err)
382 goto unlock;
383 if (memcmp(ahp->work_icv, auth_data, ahp->icv_trunc_len))
384 err = -EBADMSG;
385 }
386 unlock:
387 spin_unlock(&x->lock);
388
389 if (err)
390 goto free_out;
391
392 skb->network_header += ah_hlen;
393 memcpy(skb_network_header(skb), tmp_hdr, hdr_len);
394 skb->transport_header = skb->network_header;
395 __skb_pull(skb, ah_hlen + hdr_len);
396
397 kfree(tmp_hdr);
398
399 return nexthdr;
400
401 free_out:
402 kfree(tmp_hdr);
403 out:
404 return err;
405 }
406
407 static void ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
408 int type, int code, int offset, __be32 info)
409 {
410 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
411 struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+offset);
412 struct xfrm_state *x;
413
414 if (type != ICMPV6_DEST_UNREACH &&
415 type != ICMPV6_PKT_TOOBIG)
416 return;
417
418 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6);
419 if (!x)
420 return;
421
422 NETDEBUG(KERN_DEBUG "pmtu discovery on SA AH/%08x/" NIP6_FMT "\n",
423 ntohl(ah->spi), NIP6(iph->daddr));
424
425 xfrm_state_put(x);
426 }
427
428 static int ah6_init_state(struct xfrm_state *x)
429 {
430 struct ah_data *ahp = NULL;
431 struct xfrm_algo_desc *aalg_desc;
432 struct crypto_hash *tfm;
433
434 if (!x->aalg)
435 goto error;
436
437 if (x->encap)
438 goto error;
439
440 ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
441 if (ahp == NULL)
442 return -ENOMEM;
443
444 tfm = crypto_alloc_hash(x->aalg->alg_name, 0, CRYPTO_ALG_ASYNC);
445 if (IS_ERR(tfm))
446 goto error;
447
448 ahp->tfm = tfm;
449 if (crypto_hash_setkey(tfm, x->aalg->alg_key,
450 (x->aalg->alg_key_len + 7) / 8))
451 goto error;
452
453 /*
454 * Lookup the algorithm description maintained by xfrm_algo,
455 * verify crypto transform properties, and store information
456 * we need for AH processing. This lookup cannot fail here
457 * after a successful crypto_alloc_hash().
458 */
459 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
460 BUG_ON(!aalg_desc);
461
462 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
463 crypto_hash_digestsize(tfm)) {
464 printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
465 x->aalg->alg_name, crypto_hash_digestsize(tfm),
466 aalg_desc->uinfo.auth.icv_fullbits/8);
467 goto error;
468 }
469
470 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
471 ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
472
473 BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
474
475 ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL);
476 if (!ahp->work_icv)
477 goto error;
478
479 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
480 ahp->icv_trunc_len);
481 switch (x->props.mode) {
482 case XFRM_MODE_BEET:
483 case XFRM_MODE_TRANSPORT:
484 break;
485 case XFRM_MODE_TUNNEL:
486 x->props.header_len += sizeof(struct ipv6hdr);
487 break;
488 default:
489 goto error;
490 }
491 x->data = ahp;
492
493 return 0;
494
495 error:
496 if (ahp) {
497 kfree(ahp->work_icv);
498 crypto_free_hash(ahp->tfm);
499 kfree(ahp);
500 }
501 return -EINVAL;
502 }
503
504 static void ah6_destroy(struct xfrm_state *x)
505 {
506 struct ah_data *ahp = x->data;
507
508 if (!ahp)
509 return;
510
511 kfree(ahp->work_icv);
512 ahp->work_icv = NULL;
513 crypto_free_hash(ahp->tfm);
514 ahp->tfm = NULL;
515 kfree(ahp);
516 }
517
518 static const struct xfrm_type ah6_type =
519 {
520 .description = "AH6",
521 .owner = THIS_MODULE,
522 .proto = IPPROTO_AH,
523 .flags = XFRM_TYPE_REPLAY_PROT,
524 .init_state = ah6_init_state,
525 .destructor = ah6_destroy,
526 .input = ah6_input,
527 .output = ah6_output,
528 .hdr_offset = xfrm6_find_1stfragopt,
529 };
530
531 static struct inet6_protocol ah6_protocol = {
532 .handler = xfrm6_rcv,
533 .err_handler = ah6_err,
534 .flags = INET6_PROTO_NOPOLICY,
535 };
536
537 static int __init ah6_init(void)
538 {
539 if (xfrm_register_type(&ah6_type, AF_INET6) < 0) {
540 printk(KERN_INFO "ipv6 ah init: can't add xfrm type\n");
541 return -EAGAIN;
542 }
543
544 if (inet6_add_protocol(&ah6_protocol, IPPROTO_AH) < 0) {
545 printk(KERN_INFO "ipv6 ah init: can't add protocol\n");
546 xfrm_unregister_type(&ah6_type, AF_INET6);
547 return -EAGAIN;
548 }
549
550 return 0;
551 }
552
553 static void __exit ah6_fini(void)
554 {
555 if (inet6_del_protocol(&ah6_protocol, IPPROTO_AH) < 0)
556 printk(KERN_INFO "ipv6 ah close: can't remove protocol\n");
557
558 if (xfrm_unregister_type(&ah6_type, AF_INET6) < 0)
559 printk(KERN_INFO "ipv6 ah close: can't remove xfrm type\n");
560
561 }
562
563 module_init(ah6_init);
564 module_exit(ah6_fini);
565
566 MODULE_LICENSE("GPL");
567 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_AH);
568
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