[XFRM]: Fix leak in ah6_input
[linux-2.6.git] / 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/protocol.h>
37 #include <net/xfrm.h>
38 #include <asm/scatterlist.h>
39
40 static int zero_out_mutable_opts(struct ipv6_opt_hdr *opthdr)
41 {
42         u8 *opt = (u8 *)opthdr;
43         int len = ipv6_optlen(opthdr);
44         int off = 0;
45         int optlen = 0;
46
47         off += 2;
48         len -= 2;
49
50         while (len > 0) {
51
52                 switch (opt[off]) {
53
54                 case IPV6_TLV_PAD0:
55                         optlen = 1;
56                         break;
57                 default:
58                         if (len < 2) 
59                                 goto bad;
60                         optlen = opt[off+1]+2;
61                         if (len < optlen)
62                                 goto bad;
63                         if (opt[off] & 0x20)
64                                 memset(&opt[off+2], 0, opt[off+1]);
65                         break;
66                 }
67
68                 off += optlen;
69                 len -= optlen;
70         }
71         if (len == 0)
72                 return 1;
73
74 bad:
75         return 0;
76 }
77
78 /**
79  *      ipv6_rearrange_rthdr - rearrange IPv6 routing header
80  *      @iph: IPv6 header
81  *      @rthdr: routing header
82  *
83  *      Rearrange the destination address in @iph and the addresses in @rthdr
84  *      so that they appear in the order they will at the final destination.
85  *      See Appendix A2 of RFC 2402 for details.
86  */
87 static void ipv6_rearrange_rthdr(struct ipv6hdr *iph, struct ipv6_rt_hdr *rthdr)
88 {
89         int segments, segments_left;
90         struct in6_addr *addrs;
91         struct in6_addr final_addr;
92
93         segments_left = rthdr->segments_left;
94         if (segments_left == 0)
95                 return;
96         rthdr->segments_left = 0; 
97
98         /* The value of rthdr->hdrlen has been verified either by the system
99          * call if it is locally generated, or by ipv6_rthdr_rcv() for incoming
100          * packets.  So we can assume that it is even and that segments is
101          * greater than or equal to segments_left.
102          *
103          * For the same reason we can assume that this option is of type 0.
104          */
105         segments = rthdr->hdrlen >> 1;
106
107         addrs = ((struct rt0_hdr *)rthdr)->addr;
108         ipv6_addr_copy(&final_addr, addrs + segments - 1);
109
110         addrs += segments - segments_left;
111         memmove(addrs + 1, addrs, (segments_left - 1) * sizeof(*addrs));
112
113         ipv6_addr_copy(addrs, &iph->daddr);
114         ipv6_addr_copy(&iph->daddr, &final_addr);
115 }
116
117 static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len)
118 {
119         union {
120                 struct ipv6hdr *iph;
121                 struct ipv6_opt_hdr *opth;
122                 struct ipv6_rt_hdr *rth;
123                 char *raw;
124         } exthdr = { .iph = iph };
125         char *end = exthdr.raw + len;
126         int nexthdr = iph->nexthdr;
127
128         exthdr.iph++;
129
130         while (exthdr.raw < end) {
131                 switch (nexthdr) {
132                 case NEXTHDR_HOP:
133                 case NEXTHDR_DEST:
134                         if (!zero_out_mutable_opts(exthdr.opth)) {
135                                 LIMIT_NETDEBUG(
136                                         KERN_WARNING "overrun %sopts\n",
137                                         nexthdr == NEXTHDR_HOP ?
138                                                 "hop" : "dest");
139                                 return -EINVAL;
140                         }
141                         break;
142
143                 case NEXTHDR_ROUTING:
144                         ipv6_rearrange_rthdr(iph, exthdr.rth);
145                         break;
146
147                 default :
148                         return 0;
149                 }
150
151                 nexthdr = exthdr.opth->nexthdr;
152                 exthdr.raw += ipv6_optlen(exthdr.opth);
153         }
154
155         return 0;
156 }
157
158 static int ah6_output(struct xfrm_state *x, struct sk_buff *skb)
159 {
160         int err;
161         int extlen;
162         struct ipv6hdr *top_iph;
163         struct ip_auth_hdr *ah;
164         struct ah_data *ahp;
165         u8 nexthdr;
166         char tmp_base[8];
167         struct {
168                 struct in6_addr daddr;
169                 char hdrs[0];
170         } *tmp_ext;
171
172         top_iph = (struct ipv6hdr *)skb->data;
173         top_iph->payload_len = htons(skb->len - sizeof(*top_iph));
174
175         nexthdr = *skb->nh.raw;
176         *skb->nh.raw = IPPROTO_AH;
177
178         /* When there are no extension headers, we only need to save the first
179          * 8 bytes of the base IP header.
180          */
181         memcpy(tmp_base, top_iph, sizeof(tmp_base));
182
183         tmp_ext = NULL;
184         extlen = skb->h.raw - (unsigned char *)(top_iph + 1);
185         if (extlen) {
186                 extlen += sizeof(*tmp_ext);
187                 tmp_ext = kmalloc(extlen, GFP_ATOMIC);
188                 if (!tmp_ext) {
189                         err = -ENOMEM;
190                         goto error;
191                 }
192                 memcpy(tmp_ext, &top_iph->daddr, extlen);
193                 err = ipv6_clear_mutable_options(top_iph,
194                                                  extlen - sizeof(*tmp_ext) +
195                                                  sizeof(*top_iph));
196                 if (err)
197                         goto error_free_iph;
198         }
199
200         ah = (struct ip_auth_hdr *)skb->h.raw;
201         ah->nexthdr = nexthdr;
202
203         top_iph->priority    = 0;
204         top_iph->flow_lbl[0] = 0;
205         top_iph->flow_lbl[1] = 0;
206         top_iph->flow_lbl[2] = 0;
207         top_iph->hop_limit   = 0;
208
209         ahp = x->data;
210         ah->hdrlen  = (XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + 
211                                    ahp->icv_trunc_len) >> 2) - 2;
212
213         ah->reserved = 0;
214         ah->spi = x->id.spi;
215         ah->seq_no = htonl(++x->replay.oseq);
216         ahp->icv(ahp, skb, ah->auth_data);
217
218         err = 0;
219
220         memcpy(top_iph, tmp_base, sizeof(tmp_base));
221         if (tmp_ext) {
222                 memcpy(&top_iph->daddr, tmp_ext, extlen);
223 error_free_iph:
224                 kfree(tmp_ext);
225         }
226
227 error:
228         return err;
229 }
230
231 static int ah6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb)
232 {
233         /*
234          * Before process AH
235          * [IPv6][Ext1][Ext2][AH][Dest][Payload]
236          * |<-------------->| hdr_len
237          *
238          * To erase AH:
239          * Keeping copy of cleared headers. After AH processing,
240          * Moving the pointer of skb->nh.raw by using skb_pull as long as AH
241          * header length. Then copy back the copy as long as hdr_len
242          * If destination header following AH exists, copy it into after [Ext2].
243          * 
244          * |<>|[IPv6][Ext1][Ext2][Dest][Payload]
245          * There is offset of AH before IPv6 header after the process.
246          */
247
248         struct ipv6_auth_hdr *ah;
249         struct ah_data *ahp;
250         unsigned char *tmp_hdr = NULL;
251         u16 hdr_len;
252         u16 ah_hlen;
253         int nexthdr;
254
255         if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
256                 goto out;
257
258         /* We are going to _remove_ AH header to keep sockets happy,
259          * so... Later this can change. */
260         if (skb_cloned(skb) &&
261             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
262                 goto out;
263
264         hdr_len = skb->data - skb->nh.raw;
265         ah = (struct ipv6_auth_hdr*)skb->data;
266         ahp = x->data;
267         nexthdr = ah->nexthdr;
268         ah_hlen = (ah->hdrlen + 2) << 2;
269
270         if (ah_hlen != XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_full_len) &&
271             ah_hlen != XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_trunc_len))
272                 goto out;
273
274         if (!pskb_may_pull(skb, ah_hlen))
275                 goto out;
276
277         tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC);
278         if (!tmp_hdr)
279                 goto out;
280         memcpy(tmp_hdr, skb->nh.raw, hdr_len);
281         if (ipv6_clear_mutable_options(skb->nh.ipv6h, hdr_len))
282                 goto free_out;
283         skb->nh.ipv6h->priority    = 0;
284         skb->nh.ipv6h->flow_lbl[0] = 0;
285         skb->nh.ipv6h->flow_lbl[1] = 0;
286         skb->nh.ipv6h->flow_lbl[2] = 0;
287         skb->nh.ipv6h->hop_limit   = 0;
288
289         {
290                 u8 auth_data[MAX_AH_AUTH_LEN];
291
292                 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
293                 memset(ah->auth_data, 0, ahp->icv_trunc_len);
294                 skb_push(skb, skb->data - skb->nh.raw);
295                 ahp->icv(ahp, skb, ah->auth_data);
296                 if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) {
297                         LIMIT_NETDEBUG(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(KERN_DEBUG "pmtu discovery on SA AH/%08x/" NIP6_FMT "\n",
336                  ntohl(ah->spi), NIP6(iph->daddr));
337
338         xfrm_state_put(x);
339 }
340
341 static int ah6_init_state(struct xfrm_state *x)
342 {
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
402 error:
403         if (ahp) {
404                 kfree(ahp->work_icv);
405                 crypto_free_tfm(ahp->tfm);
406                 kfree(ahp);
407         }
408         return -EINVAL;
409 }
410
411 static void ah6_destroy(struct xfrm_state *x)
412 {
413         struct ah_data *ahp = x->data;
414
415         if (!ahp)
416                 return;
417
418         kfree(ahp->work_icv);
419         ahp->work_icv = NULL;
420         crypto_free_tfm(ahp->tfm);
421         ahp->tfm = NULL;
422         kfree(ahp);
423 }
424
425 static 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
436 static struct inet6_protocol ah6_protocol = {
437         .handler        =       xfrm6_rcv,
438         .err_handler    =       ah6_err,
439         .flags          =       INET6_PROTO_NOPOLICY,
440 };
441
442 static 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
458 static 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
468 module_init(ah6_init);
469 module_exit(ah6_fini);
470
471 MODULE_LICENSE("GPL");