[SK_BUFF]: Introduce skb_reset_transport_header(skb)
[linux-2.6.git] / net / ipv4 / ah4.c
1 #include <linux/err.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, __be32 *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 IPOPT_CIPSO:
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 = ip_hdr(skb);
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         xfrm_aevent_doreplay(x);
101         err = ah_mac_digest(ahp, skb, ah->auth_data);
102         if (err)
103                 goto error;
104         memcpy(ah->auth_data, ahp->work_icv, ahp->icv_trunc_len);
105
106         top_iph->tos = iph->tos;
107         top_iph->ttl = iph->ttl;
108         top_iph->frag_off = iph->frag_off;
109         if (top_iph->ihl != 5) {
110                 top_iph->daddr = iph->daddr;
111                 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
112         }
113
114         ip_send_check(top_iph);
115
116         err = 0;
117
118 error:
119         return err;
120 }
121
122 static int ah_input(struct xfrm_state *x, struct sk_buff *skb)
123 {
124         int ah_hlen;
125         int ihl;
126         int err = -EINVAL;
127         struct iphdr *iph;
128         struct ip_auth_hdr *ah;
129         struct ah_data *ahp;
130         char work_buf[60];
131
132         if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
133                 goto out;
134
135         ah = (struct ip_auth_hdr*)skb->data;
136         ahp = x->data;
137         ah_hlen = (ah->hdrlen + 2) << 2;
138
139         if (ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_full_len) &&
140             ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len))
141                 goto out;
142
143         if (!pskb_may_pull(skb, ah_hlen))
144                 goto out;
145
146         /* We are going to _remove_ AH header to keep sockets happy,
147          * so... Later this can change. */
148         if (skb_cloned(skb) &&
149             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
150                 goto out;
151
152         skb->ip_summed = CHECKSUM_NONE;
153
154         ah = (struct ip_auth_hdr*)skb->data;
155         iph = ip_hdr(skb);
156
157         ihl = skb->data - skb_network_header(skb);
158         memcpy(work_buf, iph, ihl);
159
160         iph->ttl = 0;
161         iph->tos = 0;
162         iph->frag_off = 0;
163         iph->check = 0;
164         if (ihl > sizeof(*iph)) {
165                 __be32 dummy;
166                 if (ip_clear_mutable_options(iph, &dummy))
167                         goto out;
168         }
169         {
170                 u8 auth_data[MAX_AH_AUTH_LEN];
171
172                 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
173                 skb_push(skb, ihl);
174                 err = ah_mac_digest(ahp, skb, ah->auth_data);
175                 if (err)
176                         goto out;
177                 err = -EINVAL;
178                 if (memcmp(ahp->work_icv, auth_data, ahp->icv_trunc_len)) {
179                         x->stats.integrity_failed++;
180                         goto out;
181                 }
182         }
183         ((struct iphdr*)work_buf)->protocol = ah->nexthdr;
184         skb->nh.raw += ah_hlen;
185         memcpy(skb_network_header(skb), work_buf, ihl);
186         skb->h.raw = skb->nh.raw;
187         __skb_pull(skb, ah_hlen + ihl);
188
189         return 0;
190
191 out:
192         return err;
193 }
194
195 static void ah4_err(struct sk_buff *skb, u32 info)
196 {
197         struct iphdr *iph = (struct iphdr*)skb->data;
198         struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+(iph->ihl<<2));
199         struct xfrm_state *x;
200
201         if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
202             skb->h.icmph->code != ICMP_FRAG_NEEDED)
203                 return;
204
205         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET);
206         if (!x)
207                 return;
208         printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n",
209                ntohl(ah->spi), ntohl(iph->daddr));
210         xfrm_state_put(x);
211 }
212
213 static int ah_init_state(struct xfrm_state *x)
214 {
215         struct ah_data *ahp = NULL;
216         struct xfrm_algo_desc *aalg_desc;
217         struct crypto_hash *tfm;
218
219         if (!x->aalg)
220                 goto error;
221
222         /* null auth can use a zero length key */
223         if (x->aalg->alg_key_len > 512)
224                 goto error;
225
226         if (x->encap)
227                 goto error;
228
229         ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
230         if (ahp == NULL)
231                 return -ENOMEM;
232
233         ahp->key = x->aalg->alg_key;
234         ahp->key_len = (x->aalg->alg_key_len+7)/8;
235         tfm = crypto_alloc_hash(x->aalg->alg_name, 0, CRYPTO_ALG_ASYNC);
236         if (IS_ERR(tfm))
237                 goto error;
238
239         ahp->tfm = tfm;
240         if (crypto_hash_setkey(tfm, ahp->key, ahp->key_len))
241                 goto error;
242
243         /*
244          * Lookup the algorithm description maintained by xfrm_algo,
245          * verify crypto transform properties, and store information
246          * we need for AH processing.  This lookup cannot fail here
247          * after a successful crypto_alloc_hash().
248          */
249         aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
250         BUG_ON(!aalg_desc);
251
252         if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
253             crypto_hash_digestsize(tfm)) {
254                 printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
255                        x->aalg->alg_name, crypto_hash_digestsize(tfm),
256                        aalg_desc->uinfo.auth.icv_fullbits/8);
257                 goto error;
258         }
259
260         ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
261         ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
262
263         BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
264
265         ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL);
266         if (!ahp->work_icv)
267                 goto error;
268
269         x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len);
270         if (x->props.mode == XFRM_MODE_TUNNEL)
271                 x->props.header_len += sizeof(struct iphdr);
272         x->data = ahp;
273
274         return 0;
275
276 error:
277         if (ahp) {
278                 kfree(ahp->work_icv);
279                 crypto_free_hash(ahp->tfm);
280                 kfree(ahp);
281         }
282         return -EINVAL;
283 }
284
285 static void ah_destroy(struct xfrm_state *x)
286 {
287         struct ah_data *ahp = x->data;
288
289         if (!ahp)
290                 return;
291
292         kfree(ahp->work_icv);
293         ahp->work_icv = NULL;
294         crypto_free_hash(ahp->tfm);
295         ahp->tfm = NULL;
296         kfree(ahp);
297 }
298
299
300 static struct xfrm_type ah_type =
301 {
302         .description    = "AH4",
303         .owner          = THIS_MODULE,
304         .proto          = IPPROTO_AH,
305         .init_state     = ah_init_state,
306         .destructor     = ah_destroy,
307         .input          = ah_input,
308         .output         = ah_output
309 };
310
311 static struct net_protocol ah4_protocol = {
312         .handler        =       xfrm4_rcv,
313         .err_handler    =       ah4_err,
314         .no_policy      =       1,
315 };
316
317 static int __init ah4_init(void)
318 {
319         if (xfrm_register_type(&ah_type, AF_INET) < 0) {
320                 printk(KERN_INFO "ip ah init: can't add xfrm type\n");
321                 return -EAGAIN;
322         }
323         if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) {
324                 printk(KERN_INFO "ip ah init: can't add protocol\n");
325                 xfrm_unregister_type(&ah_type, AF_INET);
326                 return -EAGAIN;
327         }
328         return 0;
329 }
330
331 static void __exit ah4_fini(void)
332 {
333         if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0)
334                 printk(KERN_INFO "ip ah close: can't remove protocol\n");
335         if (xfrm_unregister_type(&ah_type, AF_INET) < 0)
336                 printk(KERN_INFO "ip ah close: can't remove xfrm type\n");
337 }
338
339 module_init(ah4_init);
340 module_exit(ah4_fini);
341 MODULE_LICENSE("GPL");