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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
39static 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
73bad:
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 */
86static 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
116static 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)) {
Patrick McHardy64ce2072005-08-09 20:50:53 -0700134 LIMIT_NETDEBUG(
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135 KERN_WARNING "overrun %sopts\n",
136 nexthdr == NEXTHDR_HOP ?
Patrick McHardy64ce2072005-08-09 20:50:53 -0700137 "hop" : "dest");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138 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
157static 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);
222error_free_iph:
223 kfree(tmp_ext);
224 }
225
226error:
227 return err;
228}
229
230static 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)) {
Patrick McHardy64ce2072005-08-09 20:50:53 -0700296 LIMIT_NETDEBUG(KERN_WARNING "ipsec ah authentication error\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297 x->stats.integrity_failed++;
298 goto free_out;
299 }
300 }
301
302 skb->nh.raw = skb_pull(skb, ah_hlen);
303 memcpy(skb->nh.raw, tmp_hdr, hdr_len);
304 skb->nh.ipv6h->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
305 skb_pull(skb, hdr_len);
306 skb->h.raw = skb->data;
307
308
309 kfree(tmp_hdr);
310
311 return nexthdr;
312
313free_out:
314 kfree(tmp_hdr);
315out:
316 return -EINVAL;
317}
318
319static void ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
320 int type, int code, int offset, __u32 info)
321{
322 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
323 struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+offset);
324 struct xfrm_state *x;
325
326 if (type != ICMPV6_DEST_UNREACH &&
327 type != ICMPV6_PKT_TOOBIG)
328 return;
329
330 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6);
331 if (!x)
332 return;
333
Patrick McHardy64ce2072005-08-09 20:50:53 -0700334 NETDEBUG(KERN_DEBUG "pmtu discovery on SA AH/%08x/"
335 "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n",
336 ntohl(ah->spi), NIP6(iph->daddr));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337
338 xfrm_state_put(x);
339}
340
Herbert Xu72cb6962005-06-20 13:18:08 -0700341static int ah6_init_state(struct xfrm_state *x)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342{
343 struct ah_data *ahp = NULL;
344 struct xfrm_algo_desc *aalg_desc;
345
346 if (!x->aalg)
347 goto error;
348
349 /* null auth can use a zero length key */
350 if (x->aalg->alg_key_len > 512)
351 goto error;
352
353 if (x->encap)
354 goto error;
355
356 ahp = kmalloc(sizeof(*ahp), GFP_KERNEL);
357 if (ahp == NULL)
358 return -ENOMEM;
359
360 memset(ahp, 0, sizeof(*ahp));
361
362 ahp->key = x->aalg->alg_key;
363 ahp->key_len = (x->aalg->alg_key_len+7)/8;
364 ahp->tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
365 if (!ahp->tfm)
366 goto error;
367 ahp->icv = ah_hmac_digest;
368
369 /*
370 * Lookup the algorithm description maintained by xfrm_algo,
371 * verify crypto transform properties, and store information
372 * we need for AH processing. This lookup cannot fail here
373 * after a successful crypto_alloc_tfm().
374 */
375 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
376 BUG_ON(!aalg_desc);
377
378 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
379 crypto_tfm_alg_digestsize(ahp->tfm)) {
380 printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
381 x->aalg->alg_name, crypto_tfm_alg_digestsize(ahp->tfm),
382 aalg_desc->uinfo.auth.icv_fullbits/8);
383 goto error;
384 }
385
386 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
387 ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
388
389 BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
390
391 ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL);
392 if (!ahp->work_icv)
393 goto error;
394
395 x->props.header_len = XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_trunc_len);
396 if (x->props.mode)
397 x->props.header_len += sizeof(struct ipv6hdr);
398 x->data = ahp;
399
400 return 0;
401
402error:
403 if (ahp) {
Jesper Juhl573dbd92005-09-01 17:44:29 -0700404 kfree(ahp->work_icv);
405 crypto_free_tfm(ahp->tfm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406 kfree(ahp);
407 }
408 return -EINVAL;
409}
410
411static void ah6_destroy(struct xfrm_state *x)
412{
413 struct ah_data *ahp = x->data;
414
415 if (!ahp)
416 return;
417
Jesper Juhl573dbd92005-09-01 17:44:29 -0700418 kfree(ahp->work_icv);
419 ahp->work_icv = NULL;
420 crypto_free_tfm(ahp->tfm);
421 ahp->tfm = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422 kfree(ahp);
423}
424
425static struct xfrm_type ah6_type =
426{
427 .description = "AH6",
428 .owner = THIS_MODULE,
429 .proto = IPPROTO_AH,
430 .init_state = ah6_init_state,
431 .destructor = ah6_destroy,
432 .input = ah6_input,
433 .output = ah6_output
434};
435
436static struct inet6_protocol ah6_protocol = {
437 .handler = xfrm6_rcv,
438 .err_handler = ah6_err,
439 .flags = INET6_PROTO_NOPOLICY,
440};
441
442static int __init ah6_init(void)
443{
444 if (xfrm_register_type(&ah6_type, AF_INET6) < 0) {
445 printk(KERN_INFO "ipv6 ah init: can't add xfrm type\n");
446 return -EAGAIN;
447 }
448
449 if (inet6_add_protocol(&ah6_protocol, IPPROTO_AH) < 0) {
450 printk(KERN_INFO "ipv6 ah init: can't add protocol\n");
451 xfrm_unregister_type(&ah6_type, AF_INET6);
452 return -EAGAIN;
453 }
454
455 return 0;
456}
457
458static void __exit ah6_fini(void)
459{
460 if (inet6_del_protocol(&ah6_protocol, IPPROTO_AH) < 0)
461 printk(KERN_INFO "ipv6 ah close: can't remove protocol\n");
462
463 if (xfrm_unregister_type(&ah6_type, AF_INET6) < 0)
464 printk(KERN_INFO "ipv6 ah close: can't remove xfrm type\n");
465
466}
467
468module_init(ah6_init);
469module_exit(ah6_fini);
470
471MODULE_LICENSE("GPL");