[INET_SOCK]: Move struct inet_sock & helper functions to net/inet_sock.h
[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 <net/protocol.h>
10 #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
17 static 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
57 static 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);
100         ahp->icv(ahp, skb, ah->auth_data);
101
102         top_iph->tos = iph->tos;
103         top_iph->ttl = iph->ttl;
104         top_iph->frag_off = iph->frag_off;
105         if (top_iph->ihl != 5) {
106                 top_iph->daddr = iph->daddr;
107                 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
108         }
109
110         ip_send_check(top_iph);
111
112         err = 0;
113
114 error:
115         return err;
116 }
117
118 static int ah_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb)
119 {
120         int ah_hlen;
121         struct iphdr *iph;
122         struct ip_auth_hdr *ah;
123         struct ah_data *ahp;
124         char work_buf[60];
125
126         if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
127                 goto out;
128
129         ah = (struct ip_auth_hdr*)skb->data;
130         ahp = x->data;
131         ah_hlen = (ah->hdrlen + 2) << 2;
132         
133         if (ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_full_len) &&
134             ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len)) 
135                 goto out;
136
137         if (!pskb_may_pull(skb, ah_hlen))
138                 goto out;
139
140         /* We are going to _remove_ AH header to keep sockets happy,
141          * so... Later this can change. */
142         if (skb_cloned(skb) &&
143             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
144                 goto out;
145
146         skb->ip_summed = CHECKSUM_NONE;
147
148         ah = (struct ip_auth_hdr*)skb->data;
149         iph = skb->nh.iph;
150
151         memcpy(work_buf, iph, iph->ihl*4);
152
153         iph->ttl = 0;
154         iph->tos = 0;
155         iph->frag_off = 0;
156         iph->check = 0;
157         if (iph->ihl != 5) {
158                 u32 dummy;
159                 if (ip_clear_mutable_options(iph, &dummy))
160                         goto out;
161         }
162         {
163                 u8 auth_data[MAX_AH_AUTH_LEN];
164                 
165                 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
166                 skb_push(skb, skb->data - skb->nh.raw);
167                 ahp->icv(ahp, skb, ah->auth_data);
168                 if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) {
169                         x->stats.integrity_failed++;
170                         goto out;
171                 }
172         }
173         ((struct iphdr*)work_buf)->protocol = ah->nexthdr;
174         skb->nh.raw = skb_pull(skb, ah_hlen);
175         memcpy(skb->nh.raw, work_buf, iph->ihl*4);
176         skb->nh.iph->tot_len = htons(skb->len);
177         skb_pull(skb, skb->nh.iph->ihl*4);
178         skb->h.raw = skb->data;
179
180         return 0;
181
182 out:
183         return -EINVAL;
184 }
185
186 static void ah4_err(struct sk_buff *skb, u32 info)
187 {
188         struct iphdr *iph = (struct iphdr*)skb->data;
189         struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+(iph->ihl<<2));
190         struct xfrm_state *x;
191
192         if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
193             skb->h.icmph->code != ICMP_FRAG_NEEDED)
194                 return;
195
196         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET);
197         if (!x)
198                 return;
199         printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n",
200                ntohl(ah->spi), ntohl(iph->daddr));
201         xfrm_state_put(x);
202 }
203
204 static int ah_init_state(struct xfrm_state *x)
205 {
206         struct ah_data *ahp = NULL;
207         struct xfrm_algo_desc *aalg_desc;
208
209         if (!x->aalg)
210                 goto error;
211
212         /* null auth can use a zero length key */
213         if (x->aalg->alg_key_len > 512)
214                 goto error;
215
216         if (x->encap)
217                 goto error;
218
219         ahp = kmalloc(sizeof(*ahp), GFP_KERNEL);
220         if (ahp == NULL)
221                 return -ENOMEM;
222
223         memset(ahp, 0, sizeof(*ahp));
224
225         ahp->key = x->aalg->alg_key;
226         ahp->key_len = (x->aalg->alg_key_len+7)/8;
227         ahp->tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
228         if (!ahp->tfm)
229                 goto error;
230         ahp->icv = ah_hmac_digest;
231         
232         /*
233          * Lookup the algorithm description maintained by xfrm_algo,
234          * verify crypto transform properties, and store information
235          * we need for AH processing.  This lookup cannot fail here
236          * after a successful crypto_alloc_tfm().
237          */
238         aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
239         BUG_ON(!aalg_desc);
240
241         if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
242             crypto_tfm_alg_digestsize(ahp->tfm)) {
243                 printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
244                        x->aalg->alg_name, crypto_tfm_alg_digestsize(ahp->tfm),
245                        aalg_desc->uinfo.auth.icv_fullbits/8);
246                 goto error;
247         }
248         
249         ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
250         ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
251         
252         BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
253         
254         ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL);
255         if (!ahp->work_icv)
256                 goto error;
257         
258         x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len);
259         if (x->props.mode)
260                 x->props.header_len += sizeof(struct iphdr);
261         x->data = ahp;
262
263         return 0;
264
265 error:
266         if (ahp) {
267                 kfree(ahp->work_icv);
268                 crypto_free_tfm(ahp->tfm);
269                 kfree(ahp);
270         }
271         return -EINVAL;
272 }
273
274 static void ah_destroy(struct xfrm_state *x)
275 {
276         struct ah_data *ahp = x->data;
277
278         if (!ahp)
279                 return;
280
281         kfree(ahp->work_icv);
282         ahp->work_icv = NULL;
283         crypto_free_tfm(ahp->tfm);
284         ahp->tfm = NULL;
285         kfree(ahp);
286 }
287
288
289 static struct xfrm_type ah_type =
290 {
291         .description    = "AH4",
292         .owner          = THIS_MODULE,
293         .proto          = IPPROTO_AH,
294         .init_state     = ah_init_state,
295         .destructor     = ah_destroy,
296         .input          = ah_input,
297         .output         = ah_output
298 };
299
300 static struct net_protocol ah4_protocol = {
301         .handler        =       xfrm4_rcv,
302         .err_handler    =       ah4_err,
303         .no_policy      =       1,
304 };
305
306 static int __init ah4_init(void)
307 {
308         if (xfrm_register_type(&ah_type, AF_INET) < 0) {
309                 printk(KERN_INFO "ip ah init: can't add xfrm type\n");
310                 return -EAGAIN;
311         }
312         if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) {
313                 printk(KERN_INFO "ip ah init: can't add protocol\n");
314                 xfrm_unregister_type(&ah_type, AF_INET);
315                 return -EAGAIN;
316         }
317         return 0;
318 }
319
320 static void __exit ah4_fini(void)
321 {
322         if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0)
323                 printk(KERN_INFO "ip ah close: can't remove protocol\n");
324         if (xfrm_unregister_type(&ah_type, AF_INET) < 0)
325                 printk(KERN_INFO "ip ah close: can't remove xfrm type\n");
326 }
327
328 module_init(ah4_init);
329 module_exit(ah4_fini);
330 MODULE_LICENSE("GPL");