2 #include <linux/module.h>
6 #include <linux/crypto.h>
7 #include <linux/pfkeyv2.h>
8 #include <linux/spinlock.h>
10 #include <net/protocol.h>
11 #include <asm/scatterlist.h>
14 /* Clear mutable options and find final destination to substitute
15 * into IP header for icv calculation. Options are already checked
16 * for validity, so paranoia is not required. */
18 static int ip_clear_mutable_options(struct iphdr *iph, __be32 *daddr)
20 unsigned char * optptr = (unsigned char*)(iph+1);
21 int l = iph->ihl*4 - sizeof(struct iphdr);
34 if (optlen<2 || optlen>l)
38 case 0x85: /* Some "Extended Security" crap. */
41 case 0x80|21: /* RFC1770 */
47 memcpy(daddr, optptr+optlen-4, 4);
50 memset(optptr, 0, optlen);
58 static int ah_output(struct xfrm_state *x, struct sk_buff *skb)
61 struct iphdr *iph, *top_iph;
62 struct ip_auth_hdr *ah;
69 skb_push(skb, -skb_network_offset(skb));
70 top_iph = ip_hdr(skb);
73 iph->tos = top_iph->tos;
74 iph->ttl = top_iph->ttl;
75 iph->frag_off = top_iph->frag_off;
77 if (top_iph->ihl != 5) {
78 iph->daddr = top_iph->daddr;
79 memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
80 err = ip_clear_mutable_options(top_iph, &top_iph->daddr);
85 ah = ip_auth_hdr(skb);
86 ah->nexthdr = *skb_mac_header(skb);
87 *skb_mac_header(skb) = IPPROTO_AH;
90 top_iph->tot_len = htons(skb->len);
91 top_iph->frag_off = 0;
96 ah->hdrlen = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
100 ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq);
102 spin_lock_bh(&x->lock);
103 err = ah_mac_digest(ahp, skb, ah->auth_data);
104 memcpy(ah->auth_data, ahp->work_icv, ahp->icv_trunc_len);
105 spin_unlock_bh(&x->lock);
110 top_iph->tos = iph->tos;
111 top_iph->ttl = iph->ttl;
112 top_iph->frag_off = iph->frag_off;
113 if (top_iph->ihl != 5) {
114 top_iph->daddr = iph->daddr;
115 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
124 static int ah_input(struct xfrm_state *x, struct sk_buff *skb)
130 struct ip_auth_hdr *ah;
134 if (!pskb_may_pull(skb, sizeof(*ah)))
137 ah = (struct ip_auth_hdr *)skb->data;
139 ah_hlen = (ah->hdrlen + 2) << 2;
141 if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
142 ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
145 if (!pskb_may_pull(skb, ah_hlen))
148 /* We are going to _remove_ AH header to keep sockets happy,
149 * so... Later this can change. */
150 if (skb_cloned(skb) &&
151 pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
154 skb->ip_summed = CHECKSUM_NONE;
156 ah = (struct ip_auth_hdr *)skb->data;
159 ihl = skb->data - skb_network_header(skb);
160 memcpy(work_buf, iph, ihl);
166 if (ihl > sizeof(*iph)) {
168 if (ip_clear_mutable_options(iph, &dummy))
172 u8 auth_data[MAX_AH_AUTH_LEN];
174 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
176 err = ah_mac_digest(ahp, skb, ah->auth_data);
180 if (memcmp(ahp->work_icv, auth_data, ahp->icv_trunc_len)) {
181 x->stats.integrity_failed++;
185 ((struct iphdr*)work_buf)->protocol = ah->nexthdr;
186 skb->network_header += ah_hlen;
187 memcpy(skb_network_header(skb), work_buf, ihl);
188 skb->transport_header = skb->network_header;
189 __skb_pull(skb, ah_hlen + ihl);
197 static void ah4_err(struct sk_buff *skb, u32 info)
199 struct iphdr *iph = (struct iphdr*)skb->data;
200 struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+(iph->ihl<<2));
201 struct xfrm_state *x;
203 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
204 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
207 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET);
210 printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n",
211 ntohl(ah->spi), ntohl(iph->daddr));
215 static int ah_init_state(struct xfrm_state *x)
217 struct ah_data *ahp = NULL;
218 struct xfrm_algo_desc *aalg_desc;
219 struct crypto_hash *tfm;
227 ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
231 tfm = crypto_alloc_hash(x->aalg->alg_name, 0, CRYPTO_ALG_ASYNC);
236 if (crypto_hash_setkey(tfm, x->aalg->alg_key,
237 (x->aalg->alg_key_len + 7) / 8))
241 * Lookup the algorithm description maintained by xfrm_algo,
242 * verify crypto transform properties, and store information
243 * we need for AH processing. This lookup cannot fail here
244 * after a successful crypto_alloc_hash().
246 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
249 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
250 crypto_hash_digestsize(tfm)) {
251 printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
252 x->aalg->alg_name, crypto_hash_digestsize(tfm),
253 aalg_desc->uinfo.auth.icv_fullbits/8);
257 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
258 ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
260 BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
262 ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL);
266 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
268 if (x->props.mode == XFRM_MODE_TUNNEL)
269 x->props.header_len += sizeof(struct iphdr);
276 kfree(ahp->work_icv);
277 crypto_free_hash(ahp->tfm);
283 static void ah_destroy(struct xfrm_state *x)
285 struct ah_data *ahp = x->data;
290 kfree(ahp->work_icv);
291 ahp->work_icv = NULL;
292 crypto_free_hash(ahp->tfm);
298 static struct xfrm_type ah_type =
300 .description = "AH4",
301 .owner = THIS_MODULE,
303 .flags = XFRM_TYPE_REPLAY_PROT,
304 .init_state = ah_init_state,
305 .destructor = ah_destroy,
310 static struct net_protocol ah4_protocol = {
311 .handler = xfrm4_rcv,
312 .err_handler = ah4_err,
316 static int __init ah4_init(void)
318 if (xfrm_register_type(&ah_type, AF_INET) < 0) {
319 printk(KERN_INFO "ip ah init: can't add xfrm type\n");
322 if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) {
323 printk(KERN_INFO "ip ah init: can't add protocol\n");
324 xfrm_unregister_type(&ah_type, AF_INET);
330 static void __exit ah4_fini(void)
332 if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0)
333 printk(KERN_INFO "ip ah close: can't remove protocol\n");
334 if (xfrm_unregister_type(&ah_type, AF_INET) < 0)
335 printk(KERN_INFO "ip ah close: can't remove xfrm type\n");
338 module_init(ah4_init);
339 module_exit(ah4_fini);
340 MODULE_LICENSE("GPL");
341 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH);