blob: 8219b7e0968d1df51a315b2880bf35be09888ab3 [file] [log] [blame]
Herbert Xu07d4ee52006-08-20 14:24:50 +10001#include <linux/err.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002#include <linux/module.h>
3#include <net/ip.h>
4#include <net/xfrm.h>
5#include <net/ah.h>
6#include <linux/crypto.h>
7#include <linux/pfkeyv2.h>
Herbert Xub7c65382007-10-09 13:33:35 -07008#include <linux/spinlock.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07009#include <net/icmp.h>
Arnaldo Carvalho de Melo14c85022005-12-27 02:43:12 -020010#include <net/protocol.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070011
12
13/* Clear mutable options and find final destination to substitute
14 * into IP header for icv calculation. Options are already checked
15 * for validity, so paranoia is not required. */
16
Al Virod5a0a1e2006-11-08 00:23:14 -080017static int ip_clear_mutable_options(struct iphdr *iph, __be32 *daddr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070018{
19 unsigned char * optptr = (unsigned char*)(iph+1);
20 int l = iph->ihl*4 - sizeof(struct iphdr);
21 int optlen;
22
23 while (l > 0) {
24 switch (*optptr) {
25 case IPOPT_END:
26 return 0;
27 case IPOPT_NOOP:
28 l--;
29 optptr++;
30 continue;
31 }
32 optlen = optptr[1];
33 if (optlen<2 || optlen>l)
34 return -EINVAL;
35 switch (*optptr) {
36 case IPOPT_SEC:
37 case 0x85: /* Some "Extended Security" crap. */
Paul Moore11a03f72006-08-03 16:46:20 -070038 case IPOPT_CIPSO:
Linus Torvalds1da177e2005-04-16 15:20:36 -070039 case IPOPT_RA:
40 case 0x80|21: /* RFC1770 */
41 break;
42 case IPOPT_LSRR:
43 case IPOPT_SSRR:
44 if (optlen < 6)
45 return -EINVAL;
46 memcpy(daddr, optptr+optlen-4, 4);
47 /* Fall through */
48 default:
Nick Bowler96fe1c02007-08-22 12:33:51 -070049 memset(optptr, 0, optlen);
Linus Torvalds1da177e2005-04-16 15:20:36 -070050 }
51 l -= optlen;
52 optptr += optlen;
53 }
54 return 0;
55}
56
57static int ah_output(struct xfrm_state *x, struct sk_buff *skb)
58{
59 int err;
60 struct iphdr *iph, *top_iph;
61 struct ip_auth_hdr *ah;
62 struct ah_data *ahp;
63 union {
64 struct iphdr iph;
65 char buf[60];
66 } tmp_iph;
67
Herbert Xu7b277b12007-10-10 15:44:06 -070068 skb_push(skb, -skb_network_offset(skb));
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -070069 top_iph = ip_hdr(skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -070070 iph = &tmp_iph.iph;
71
72 iph->tos = top_iph->tos;
73 iph->ttl = top_iph->ttl;
74 iph->frag_off = top_iph->frag_off;
75
76 if (top_iph->ihl != 5) {
77 iph->daddr = top_iph->daddr;
78 memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
79 err = ip_clear_mutable_options(top_iph, &top_iph->daddr);
80 if (err)
81 goto error;
82 }
83
Herbert Xu87bdc482007-10-10 15:45:25 -070084 ah = ip_auth_hdr(skb);
Herbert Xu37fedd32007-10-10 15:44:44 -070085 ah->nexthdr = *skb_mac_header(skb);
86 *skb_mac_header(skb) = IPPROTO_AH;
Linus Torvalds1da177e2005-04-16 15:20:36 -070087
88 top_iph->tos = 0;
89 top_iph->tot_len = htons(skb->len);
90 top_iph->frag_off = 0;
91 top_iph->ttl = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 top_iph->check = 0;
93
94 ahp = x->data;
Herbert Xu87bdc482007-10-10 15:45:25 -070095 ah->hdrlen = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -070096
97 ah->reserved = 0;
98 ah->spi = x->id.spi;
Herbert Xub318e0e2008-02-12 22:50:35 -080099 ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output);
Herbert Xub7c65382007-10-09 13:33:35 -0700100
101 spin_lock_bh(&x->lock);
Herbert Xu07d4ee52006-08-20 14:24:50 +1000102 err = ah_mac_digest(ahp, skb, ah->auth_data);
Herbert Xub7c65382007-10-09 13:33:35 -0700103 memcpy(ah->auth_data, ahp->work_icv, ahp->icv_trunc_len);
104 spin_unlock_bh(&x->lock);
105
Herbert Xu07d4ee52006-08-20 14:24:50 +1000106 if (err)
107 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108
109 top_iph->tos = iph->tos;
110 top_iph->ttl = iph->ttl;
111 top_iph->frag_off = iph->frag_off;
112 if (top_iph->ihl != 5) {
113 top_iph->daddr = iph->daddr;
114 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
115 }
116
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 err = 0;
118
119error:
120 return err;
121}
122
Herbert Xue6956332006-04-01 00:52:46 -0800123static int ah_input(struct xfrm_state *x, struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124{
125 int ah_hlen;
Herbert Xu31a4ab92006-05-27 23:06:13 -0700126 int ihl;
Herbert Xu631a6692007-10-10 15:46:21 -0700127 int nexthdr;
Herbert Xu07d4ee52006-08-20 14:24:50 +1000128 int err = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 struct iphdr *iph;
130 struct ip_auth_hdr *ah;
131 struct ah_data *ahp;
132 char work_buf[60];
133
Herbert Xu87bdc482007-10-10 15:45:25 -0700134 if (!pskb_may_pull(skb, sizeof(*ah)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135 goto out;
136
Herbert Xu87bdc482007-10-10 15:45:25 -0700137 ah = (struct ip_auth_hdr *)skb->data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138 ahp = x->data;
Herbert Xu631a6692007-10-10 15:46:21 -0700139 nexthdr = ah->nexthdr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140 ah_hlen = (ah->hdrlen + 2) << 2;
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900141
Herbert Xu87bdc482007-10-10 15:45:25 -0700142 if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
143 ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144 goto out;
145
146 if (!pskb_may_pull(skb, ah_hlen))
147 goto out;
148
149 /* We are going to _remove_ AH header to keep sockets happy,
150 * so... Later this can change. */
151 if (skb_cloned(skb) &&
152 pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
153 goto out;
154
155 skb->ip_summed = CHECKSUM_NONE;
156
Herbert Xu87bdc482007-10-10 15:45:25 -0700157 ah = (struct ip_auth_hdr *)skb->data;
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -0700158 iph = ip_hdr(skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159
Arnaldo Carvalho de Melod56f90a2007-04-10 20:50:43 -0700160 ihl = skb->data - skb_network_header(skb);
Herbert Xu31a4ab92006-05-27 23:06:13 -0700161 memcpy(work_buf, iph, ihl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162
163 iph->ttl = 0;
164 iph->tos = 0;
165 iph->frag_off = 0;
166 iph->check = 0;
Herbert Xu31a4ab92006-05-27 23:06:13 -0700167 if (ihl > sizeof(*iph)) {
Al Virod5a0a1e2006-11-08 00:23:14 -0800168 __be32 dummy;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169 if (ip_clear_mutable_options(iph, &dummy))
170 goto out;
171 }
Herbert Xu0ebea8e2007-11-13 21:45:58 -0800172
173 spin_lock(&x->lock);
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900174 {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 u8 auth_data[MAX_AH_AUTH_LEN];
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900176
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
Herbert Xu31a4ab92006-05-27 23:06:13 -0700178 skb_push(skb, ihl);
Herbert Xu07d4ee52006-08-20 14:24:50 +1000179 err = ah_mac_digest(ahp, skb, ah->auth_data);
180 if (err)
Herbert Xu0ebea8e2007-11-13 21:45:58 -0800181 goto unlock;
Herbert Xu9dd32452007-12-30 21:10:30 -0800182 if (memcmp(ahp->work_icv, auth_data, ahp->icv_trunc_len))
Herbert Xu668dc8a2007-12-16 15:55:02 -0800183 err = -EBADMSG;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184 }
Herbert Xu0ebea8e2007-11-13 21:45:58 -0800185unlock:
186 spin_unlock(&x->lock);
187
188 if (err)
189 goto out;
190
Arnaldo Carvalho de Melob0e380b2007-04-10 21:21:55 -0700191 skb->network_header += ah_hlen;
Arnaldo Carvalho de Melobadff6d2007-03-13 13:06:52 -0300192 memcpy(skb_network_header(skb), work_buf, ihl);
Arnaldo Carvalho de Melob0e380b2007-04-10 21:21:55 -0700193 skb->transport_header = skb->network_header;
Herbert Xu31a4ab92006-05-27 23:06:13 -0700194 __skb_pull(skb, ah_hlen + ihl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195
Herbert Xu631a6692007-10-10 15:46:21 -0700196 return nexthdr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197
198out:
Herbert Xu07d4ee52006-08-20 14:24:50 +1000199 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200}
201
202static void ah4_err(struct sk_buff *skb, u32 info)
203{
204 struct iphdr *iph = (struct iphdr*)skb->data;
205 struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+(iph->ihl<<2));
206 struct xfrm_state *x;
207
Arnaldo Carvalho de Melo88c76642007-03-13 14:43:18 -0300208 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
209 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 return;
211
212 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET);
213 if (!x)
214 return;
215 printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n",
216 ntohl(ah->spi), ntohl(iph->daddr));
217 xfrm_state_put(x);
218}
219
Herbert Xu72cb6962005-06-20 13:18:08 -0700220static int ah_init_state(struct xfrm_state *x)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221{
222 struct ah_data *ahp = NULL;
223 struct xfrm_algo_desc *aalg_desc;
Herbert Xu07d4ee52006-08-20 14:24:50 +1000224 struct crypto_hash *tfm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225
226 if (!x->aalg)
227 goto error;
228
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229 if (x->encap)
230 goto error;
231
Panagiotis Issaris0da974f2006-07-21 14:51:30 -0700232 ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233 if (ahp == NULL)
234 return -ENOMEM;
235
Herbert Xu07d4ee52006-08-20 14:24:50 +1000236 tfm = crypto_alloc_hash(x->aalg->alg_name, 0, CRYPTO_ALG_ASYNC);
237 if (IS_ERR(tfm))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238 goto error;
Herbert Xu07d4ee52006-08-20 14:24:50 +1000239
240 ahp->tfm = tfm;
Herbert Xubc31d3b2007-10-08 17:14:34 -0700241 if (crypto_hash_setkey(tfm, x->aalg->alg_key,
242 (x->aalg->alg_key_len + 7) / 8))
Herbert Xu07d4ee52006-08-20 14:24:50 +1000243 goto error;
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900244
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 /*
246 * Lookup the algorithm description maintained by xfrm_algo,
247 * verify crypto transform properties, and store information
248 * we need for AH processing. This lookup cannot fail here
Herbert Xu07d4ee52006-08-20 14:24:50 +1000249 * after a successful crypto_alloc_hash().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250 */
251 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
252 BUG_ON(!aalg_desc);
253
254 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
Herbert Xu07d4ee52006-08-20 14:24:50 +1000255 crypto_hash_digestsize(tfm)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
Herbert Xu07d4ee52006-08-20 14:24:50 +1000257 x->aalg->alg_name, crypto_hash_digestsize(tfm),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258 aalg_desc->uinfo.auth.icv_fullbits/8);
259 goto error;
260 }
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900261
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
263 ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900264
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265 BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900266
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267 ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL);
268 if (!ahp->work_icv)
269 goto error;
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900270
Herbert Xu87bdc482007-10-10 15:45:25 -0700271 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
272 ahp->icv_trunc_len);
Masahide NAKAMURA7e49e6d2006-09-22 15:05:15 -0700273 if (x->props.mode == XFRM_MODE_TUNNEL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 x->props.header_len += sizeof(struct iphdr);
275 x->data = ahp;
276
277 return 0;
278
279error:
280 if (ahp) {
Jesper Juhl573dbd92005-09-01 17:44:29 -0700281 kfree(ahp->work_icv);
Herbert Xu07d4ee52006-08-20 14:24:50 +1000282 crypto_free_hash(ahp->tfm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 kfree(ahp);
284 }
285 return -EINVAL;
286}
287
288static void ah_destroy(struct xfrm_state *x)
289{
290 struct ah_data *ahp = x->data;
291
292 if (!ahp)
293 return;
294
Jesper Juhl573dbd92005-09-01 17:44:29 -0700295 kfree(ahp->work_icv);
296 ahp->work_icv = NULL;
Herbert Xu07d4ee52006-08-20 14:24:50 +1000297 crypto_free_hash(ahp->tfm);
Jesper Juhl573dbd92005-09-01 17:44:29 -0700298 ahp->tfm = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 kfree(ahp);
300}
301
302
Eric Dumazet533cb5b2008-01-30 19:11:50 -0800303static const struct xfrm_type ah_type =
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304{
305 .description = "AH4",
306 .owner = THIS_MODULE,
307 .proto = IPPROTO_AH,
Herbert Xu436a0a42007-10-08 17:25:53 -0700308 .flags = XFRM_TYPE_REPLAY_PROT,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309 .init_state = ah_init_state,
310 .destructor = ah_destroy,
311 .input = ah_input,
312 .output = ah_output
313};
314
315static struct net_protocol ah4_protocol = {
316 .handler = xfrm4_rcv,
317 .err_handler = ah4_err,
318 .no_policy = 1,
319};
320
321static int __init ah4_init(void)
322{
323 if (xfrm_register_type(&ah_type, AF_INET) < 0) {
324 printk(KERN_INFO "ip ah init: can't add xfrm type\n");
325 return -EAGAIN;
326 }
327 if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) {
328 printk(KERN_INFO "ip ah init: can't add protocol\n");
329 xfrm_unregister_type(&ah_type, AF_INET);
330 return -EAGAIN;
331 }
332 return 0;
333}
334
335static void __exit ah4_fini(void)
336{
337 if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0)
338 printk(KERN_INFO "ip ah close: can't remove protocol\n");
339 if (xfrm_unregister_type(&ah_type, AF_INET) < 0)
340 printk(KERN_INFO "ip ah close: can't remove xfrm type\n");
341}
342
343module_init(ah4_init);
344module_exit(ah4_fini);
345MODULE_LICENSE("GPL");
Masahide NAKAMURAd3d6dd32007-06-26 23:57:49 -0700346MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH);