Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6
[linux-2.6] / net / ipv6 / ah6.c
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)
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");