blob: 514c85b2631a3332187141c2afdd7ed7825314cb [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>
9#include <asm/scatterlist.h>
10
11
12/* Clear mutable options and find final destination to substitute
13 * into IP header for icv calculation. Options are already checked
14 * for validity, so paranoia is not required. */
15
16static int ip_clear_mutable_options(struct iphdr *iph, u32 *daddr)
17{
18 unsigned char * optptr = (unsigned char*)(iph+1);
19 int l = iph->ihl*4 - sizeof(struct iphdr);
20 int optlen;
21
22 while (l > 0) {
23 switch (*optptr) {
24 case IPOPT_END:
25 return 0;
26 case IPOPT_NOOP:
27 l--;
28 optptr++;
29 continue;
30 }
31 optlen = optptr[1];
32 if (optlen<2 || optlen>l)
33 return -EINVAL;
34 switch (*optptr) {
35 case IPOPT_SEC:
36 case 0x85: /* Some "Extended Security" crap. */
37 case 0x86: /* Another "Commercial Security" crap. */
38 case IPOPT_RA:
39 case 0x80|21: /* RFC1770 */
40 break;
41 case IPOPT_LSRR:
42 case IPOPT_SSRR:
43 if (optlen < 6)
44 return -EINVAL;
45 memcpy(daddr, optptr+optlen-4, 4);
46 /* Fall through */
47 default:
48 memset(optptr+2, 0, optlen-2);
49 }
50 l -= optlen;
51 optptr += optlen;
52 }
53 return 0;
54}
55
56static int ah_output(struct xfrm_state *x, struct sk_buff *skb)
57{
58 int err;
59 struct iphdr *iph, *top_iph;
60 struct ip_auth_hdr *ah;
61 struct ah_data *ahp;
62 union {
63 struct iphdr iph;
64 char buf[60];
65 } tmp_iph;
66
67 top_iph = skb->nh.iph;
68 iph = &tmp_iph.iph;
69
70 iph->tos = top_iph->tos;
71 iph->ttl = top_iph->ttl;
72 iph->frag_off = top_iph->frag_off;
73
74 if (top_iph->ihl != 5) {
75 iph->daddr = top_iph->daddr;
76 memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
77 err = ip_clear_mutable_options(top_iph, &top_iph->daddr);
78 if (err)
79 goto error;
80 }
81
82 ah = (struct ip_auth_hdr *)((char *)top_iph+top_iph->ihl*4);
83 ah->nexthdr = top_iph->protocol;
84
85 top_iph->tos = 0;
86 top_iph->tot_len = htons(skb->len);
87 top_iph->frag_off = 0;
88 top_iph->ttl = 0;
89 top_iph->protocol = IPPROTO_AH;
90 top_iph->check = 0;
91
92 ahp = x->data;
93 ah->hdrlen = (XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
94 ahp->icv_trunc_len) >> 2) - 2;
95
96 ah->reserved = 0;
97 ah->spi = x->id.spi;
98 ah->seq_no = htonl(++x->replay.oseq);
99 ahp->icv(ahp, skb, ah->auth_data);
100
101 top_iph->tos = iph->tos;
102 top_iph->ttl = iph->ttl;
103 top_iph->frag_off = iph->frag_off;
104 if (top_iph->ihl != 5) {
105 top_iph->daddr = iph->daddr;
106 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
107 }
108
109 ip_send_check(top_iph);
110
111 err = 0;
112
113error:
114 return err;
115}
116
117static int ah_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb)
118{
119 int ah_hlen;
120 struct iphdr *iph;
121 struct ip_auth_hdr *ah;
122 struct ah_data *ahp;
123 char work_buf[60];
124
125 if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
126 goto out;
127
128 ah = (struct ip_auth_hdr*)skb->data;
129 ahp = x->data;
130 ah_hlen = (ah->hdrlen + 2) << 2;
131
132 if (ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_full_len) &&
133 ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len))
134 goto out;
135
136 if (!pskb_may_pull(skb, ah_hlen))
137 goto out;
138
139 /* We are going to _remove_ AH header to keep sockets happy,
140 * so... Later this can change. */
141 if (skb_cloned(skb) &&
142 pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
143 goto out;
144
145 skb->ip_summed = CHECKSUM_NONE;
146
147 ah = (struct ip_auth_hdr*)skb->data;
148 iph = skb->nh.iph;
149
150 memcpy(work_buf, iph, iph->ihl*4);
151
152 iph->ttl = 0;
153 iph->tos = 0;
154 iph->frag_off = 0;
155 iph->check = 0;
156 if (iph->ihl != 5) {
157 u32 dummy;
158 if (ip_clear_mutable_options(iph, &dummy))
159 goto out;
160 }
161 {
162 u8 auth_data[MAX_AH_AUTH_LEN];
163
164 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
165 skb_push(skb, skb->data - skb->nh.raw);
166 ahp->icv(ahp, skb, ah->auth_data);
167 if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) {
168 x->stats.integrity_failed++;
169 goto out;
170 }
171 }
172 ((struct iphdr*)work_buf)->protocol = ah->nexthdr;
173 skb->nh.raw = skb_pull(skb, ah_hlen);
174 memcpy(skb->nh.raw, work_buf, iph->ihl*4);
175 skb->nh.iph->tot_len = htons(skb->len);
176 skb_pull(skb, skb->nh.iph->ihl*4);
177 skb->h.raw = skb->data;
178
179 return 0;
180
181out:
182 return -EINVAL;
183}
184
185static void ah4_err(struct sk_buff *skb, u32 info)
186{
187 struct iphdr *iph = (struct iphdr*)skb->data;
188 struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+(iph->ihl<<2));
189 struct xfrm_state *x;
190
191 if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
192 skb->h.icmph->code != ICMP_FRAG_NEEDED)
193 return;
194
195 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET);
196 if (!x)
197 return;
198 printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n",
199 ntohl(ah->spi), ntohl(iph->daddr));
200 xfrm_state_put(x);
201}
202
Herbert Xu72cb6962005-06-20 13:18:08 -0700203static int ah_init_state(struct xfrm_state *x)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204{
205 struct ah_data *ahp = NULL;
206 struct xfrm_algo_desc *aalg_desc;
207
208 if (!x->aalg)
209 goto error;
210
211 /* null auth can use a zero length key */
212 if (x->aalg->alg_key_len > 512)
213 goto error;
214
215 if (x->encap)
216 goto error;
217
218 ahp = kmalloc(sizeof(*ahp), GFP_KERNEL);
219 if (ahp == NULL)
220 return -ENOMEM;
221
222 memset(ahp, 0, sizeof(*ahp));
223
224 ahp->key = x->aalg->alg_key;
225 ahp->key_len = (x->aalg->alg_key_len+7)/8;
226 ahp->tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
227 if (!ahp->tfm)
228 goto error;
229 ahp->icv = ah_hmac_digest;
230
231 /*
232 * Lookup the algorithm description maintained by xfrm_algo,
233 * verify crypto transform properties, and store information
234 * we need for AH processing. This lookup cannot fail here
235 * after a successful crypto_alloc_tfm().
236 */
237 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
238 BUG_ON(!aalg_desc);
239
240 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
241 crypto_tfm_alg_digestsize(ahp->tfm)) {
242 printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
243 x->aalg->alg_name, crypto_tfm_alg_digestsize(ahp->tfm),
244 aalg_desc->uinfo.auth.icv_fullbits/8);
245 goto error;
246 }
247
248 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
249 ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
250
251 BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
252
253 ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL);
254 if (!ahp->work_icv)
255 goto error;
256
257 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len);
258 if (x->props.mode)
259 x->props.header_len += sizeof(struct iphdr);
260 x->data = ahp;
261
262 return 0;
263
264error:
265 if (ahp) {
266 if (ahp->work_icv)
267 kfree(ahp->work_icv);
268 if (ahp->tfm)
269 crypto_free_tfm(ahp->tfm);
270 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
282 if (ahp->work_icv) {
283 kfree(ahp->work_icv);
284 ahp->work_icv = NULL;
285 }
286 if (ahp->tfm) {
287 crypto_free_tfm(ahp->tfm);
288 ahp->tfm = NULL;
289 }
290 kfree(ahp);
291}
292
293
294static struct xfrm_type ah_type =
295{
296 .description = "AH4",
297 .owner = THIS_MODULE,
298 .proto = IPPROTO_AH,
299 .init_state = ah_init_state,
300 .destructor = ah_destroy,
301 .input = ah_input,
302 .output = ah_output
303};
304
305static struct net_protocol ah4_protocol = {
306 .handler = xfrm4_rcv,
307 .err_handler = ah4_err,
308 .no_policy = 1,
309};
310
311static int __init ah4_init(void)
312{
313 if (xfrm_register_type(&ah_type, AF_INET) < 0) {
314 printk(KERN_INFO "ip ah init: can't add xfrm type\n");
315 return -EAGAIN;
316 }
317 if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) {
318 printk(KERN_INFO "ip ah init: can't add protocol\n");
319 xfrm_unregister_type(&ah_type, AF_INET);
320 return -EAGAIN;
321 }
322 return 0;
323}
324
325static void __exit ah4_fini(void)
326{
327 if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0)
328 printk(KERN_INFO "ip ah close: can't remove protocol\n");
329 if (xfrm_unregister_type(&ah_type, AF_INET) < 0)
330 printk(KERN_INFO "ip ah close: can't remove xfrm type\n");
331}
332
333module_init(ah4_init);
334module_exit(ah4_fini);
335MODULE_LICENSE("GPL");