blob: e16d8b42b953bfd93de8be94b787353dfcc9f192 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001#include <linux/config.h>
2#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>
8#include <net/icmp.h>
Arnaldo Carvalho de Melo14c85022005-12-27 02:43:12 -02009#include <net/protocol.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070010#include <asm/scatterlist.h>
11
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
17static int ip_clear_mutable_options(struct iphdr *iph, u32 *daddr)
18{
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. */
38 case 0x86: /* Another "Commercial Security" crap. */
39 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:
49 memset(optptr+2, 0, optlen-2);
50 }
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
68 top_iph = skb->nh.iph;
69 iph = &tmp_iph.iph;
70
71 iph->tos = top_iph->tos;
72 iph->ttl = top_iph->ttl;
73 iph->frag_off = top_iph->frag_off;
74
75 if (top_iph->ihl != 5) {
76 iph->daddr = top_iph->daddr;
77 memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
78 err = ip_clear_mutable_options(top_iph, &top_iph->daddr);
79 if (err)
80 goto error;
81 }
82
83 ah = (struct ip_auth_hdr *)((char *)top_iph+top_iph->ihl*4);
84 ah->nexthdr = top_iph->protocol;
85
86 top_iph->tos = 0;
87 top_iph->tot_len = htons(skb->len);
88 top_iph->frag_off = 0;
89 top_iph->ttl = 0;
90 top_iph->protocol = IPPROTO_AH;
91 top_iph->check = 0;
92
93 ahp = x->data;
94 ah->hdrlen = (XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
95 ahp->icv_trunc_len) >> 2) - 2;
96
97 ah->reserved = 0;
98 ah->spi = x->id.spi;
99 ah->seq_no = htonl(++x->replay.oseq);
Jamal Hadi Salim9500e8a2006-03-20 19:15:29 -0800100 xfrm_aevent_doreplay(x);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 ahp->icv(ahp, skb, ah->auth_data);
102
103 top_iph->tos = iph->tos;
104 top_iph->ttl = iph->ttl;
105 top_iph->frag_off = iph->frag_off;
106 if (top_iph->ihl != 5) {
107 top_iph->daddr = iph->daddr;
108 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
109 }
110
111 ip_send_check(top_iph);
112
113 err = 0;
114
115error:
116 return err;
117}
118
119static int ah_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb)
120{
121 int ah_hlen;
122 struct iphdr *iph;
123 struct ip_auth_hdr *ah;
124 struct ah_data *ahp;
125 char work_buf[60];
126
127 if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
128 goto out;
129
130 ah = (struct ip_auth_hdr*)skb->data;
131 ahp = x->data;
132 ah_hlen = (ah->hdrlen + 2) << 2;
133
134 if (ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_full_len) &&
135 ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len))
136 goto out;
137
138 if (!pskb_may_pull(skb, ah_hlen))
139 goto out;
140
141 /* We are going to _remove_ AH header to keep sockets happy,
142 * so... Later this can change. */
143 if (skb_cloned(skb) &&
144 pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
145 goto out;
146
147 skb->ip_summed = CHECKSUM_NONE;
148
149 ah = (struct ip_auth_hdr*)skb->data;
150 iph = skb->nh.iph;
151
152 memcpy(work_buf, iph, iph->ihl*4);
153
154 iph->ttl = 0;
155 iph->tos = 0;
156 iph->frag_off = 0;
157 iph->check = 0;
158 if (iph->ihl != 5) {
159 u32 dummy;
160 if (ip_clear_mutable_options(iph, &dummy))
161 goto out;
162 }
163 {
164 u8 auth_data[MAX_AH_AUTH_LEN];
165
166 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
167 skb_push(skb, skb->data - skb->nh.raw);
168 ahp->icv(ahp, skb, ah->auth_data);
169 if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) {
170 x->stats.integrity_failed++;
171 goto out;
172 }
173 }
174 ((struct iphdr*)work_buf)->protocol = ah->nexthdr;
175 skb->nh.raw = skb_pull(skb, ah_hlen);
176 memcpy(skb->nh.raw, work_buf, iph->ihl*4);
177 skb->nh.iph->tot_len = htons(skb->len);
178 skb_pull(skb, skb->nh.iph->ihl*4);
179 skb->h.raw = skb->data;
180
181 return 0;
182
183out:
184 return -EINVAL;
185}
186
187static void ah4_err(struct sk_buff *skb, u32 info)
188{
189 struct iphdr *iph = (struct iphdr*)skb->data;
190 struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+(iph->ihl<<2));
191 struct xfrm_state *x;
192
193 if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
194 skb->h.icmph->code != ICMP_FRAG_NEEDED)
195 return;
196
197 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET);
198 if (!x)
199 return;
200 printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n",
201 ntohl(ah->spi), ntohl(iph->daddr));
202 xfrm_state_put(x);
203}
204
Herbert Xu72cb6962005-06-20 13:18:08 -0700205static int ah_init_state(struct xfrm_state *x)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206{
207 struct ah_data *ahp = NULL;
208 struct xfrm_algo_desc *aalg_desc;
209
210 if (!x->aalg)
211 goto error;
212
213 /* null auth can use a zero length key */
214 if (x->aalg->alg_key_len > 512)
215 goto error;
216
217 if (x->encap)
218 goto error;
219
220 ahp = kmalloc(sizeof(*ahp), GFP_KERNEL);
221 if (ahp == NULL)
222 return -ENOMEM;
223
224 memset(ahp, 0, sizeof(*ahp));
225
226 ahp->key = x->aalg->alg_key;
227 ahp->key_len = (x->aalg->alg_key_len+7)/8;
228 ahp->tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
229 if (!ahp->tfm)
230 goto error;
231 ahp->icv = ah_hmac_digest;
232
233 /*
234 * Lookup the algorithm description maintained by xfrm_algo,
235 * verify crypto transform properties, and store information
236 * we need for AH processing. This lookup cannot fail here
237 * after a successful crypto_alloc_tfm().
238 */
239 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
240 BUG_ON(!aalg_desc);
241
242 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
243 crypto_tfm_alg_digestsize(ahp->tfm)) {
244 printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
245 x->aalg->alg_name, crypto_tfm_alg_digestsize(ahp->tfm),
246 aalg_desc->uinfo.auth.icv_fullbits/8);
247 goto error;
248 }
249
250 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
251 ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
252
253 BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
254
255 ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL);
256 if (!ahp->work_icv)
257 goto error;
258
259 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len);
260 if (x->props.mode)
261 x->props.header_len += sizeof(struct iphdr);
262 x->data = ahp;
263
264 return 0;
265
266error:
267 if (ahp) {
Jesper Juhl573dbd92005-09-01 17:44:29 -0700268 kfree(ahp->work_icv);
269 crypto_free_tfm(ahp->tfm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270 kfree(ahp);
271 }
272 return -EINVAL;
273}
274
275static void ah_destroy(struct xfrm_state *x)
276{
277 struct ah_data *ahp = x->data;
278
279 if (!ahp)
280 return;
281
Jesper Juhl573dbd92005-09-01 17:44:29 -0700282 kfree(ahp->work_icv);
283 ahp->work_icv = NULL;
284 crypto_free_tfm(ahp->tfm);
285 ahp->tfm = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 kfree(ahp);
287}
288
289
290static struct xfrm_type ah_type =
291{
292 .description = "AH4",
293 .owner = THIS_MODULE,
294 .proto = IPPROTO_AH,
295 .init_state = ah_init_state,
296 .destructor = ah_destroy,
297 .input = ah_input,
298 .output = ah_output
299};
300
301static struct net_protocol ah4_protocol = {
302 .handler = xfrm4_rcv,
303 .err_handler = ah4_err,
304 .no_policy = 1,
305};
306
307static int __init ah4_init(void)
308{
309 if (xfrm_register_type(&ah_type, AF_INET) < 0) {
310 printk(KERN_INFO "ip ah init: can't add xfrm type\n");
311 return -EAGAIN;
312 }
313 if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) {
314 printk(KERN_INFO "ip ah init: can't add protocol\n");
315 xfrm_unregister_type(&ah_type, AF_INET);
316 return -EAGAIN;
317 }
318 return 0;
319}
320
321static void __exit ah4_fini(void)
322{
323 if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0)
324 printk(KERN_INFO "ip ah close: can't remove protocol\n");
325 if (xfrm_unregister_type(&ah_type, AF_INET) < 0)
326 printk(KERN_INFO "ip ah close: can't remove xfrm type\n");
327}
328
329module_init(ah4_init);
330module_exit(ah4_fini);
331MODULE_LICENSE("GPL");