[IPSEC]: Add xfrm_init_state
[linux-2.6.git] / net / ipv4 / ah4.c
1 #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
16 static 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
56 static 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
113 error:
114         return err;
115 }
116
117 static 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
181 out:
182         return -EINVAL;
183 }
184
185 static 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
203 static int ah_init_state(struct xfrm_state *x)
204 {
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
264 error:
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
275 static 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
294 static 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
305 static struct net_protocol ah4_protocol = {
306         .handler        =       xfrm4_rcv,
307         .err_handler    =       ah4_err,
308         .no_policy      =       1,
309 };
310
311 static 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
325 static 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
333 module_init(ah4_init);
334 module_exit(ah4_fini);
335 MODULE_LICENSE("GPL");