2 #include <linux/module.h>
6 #include <linux/crypto.h>
7 #include <linux/pfkeyv2.h>
9 #include <net/protocol.h>
10 #include <asm/scatterlist.h>
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. */
17 static int ip_clear_mutable_options(struct iphdr *iph, __be32 *daddr)
19 unsigned char * optptr = (unsigned char*)(iph+1);
20 int l = iph->ihl*4 - sizeof(struct iphdr);
33 if (optlen<2 || optlen>l)
37 case 0x85: /* Some "Extended Security" crap. */
40 case 0x80|21: /* RFC1770 */
46 memcpy(daddr, optptr+optlen-4, 4);
49 memset(optptr, 0, optlen);
57 static int ah_output(struct xfrm_state *x, struct sk_buff *skb)
60 struct iphdr *iph, *top_iph;
61 struct ip_auth_hdr *ah;
68 top_iph = ip_hdr(skb);
71 iph->tos = top_iph->tos;
72 iph->ttl = top_iph->ttl;
73 iph->frag_off = top_iph->frag_off;
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);
83 ah = (struct ip_auth_hdr *)((char *)top_iph+top_iph->ihl*4);
84 ah->nexthdr = top_iph->protocol;
87 top_iph->tot_len = htons(skb->len);
88 top_iph->frag_off = 0;
90 top_iph->protocol = IPPROTO_AH;
94 ah->hdrlen = (XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
95 ahp->icv_trunc_len) >> 2) - 2;
99 ah->seq_no = htonl(++x->replay.oseq);
100 xfrm_aevent_doreplay(x);
101 err = ah_mac_digest(ahp, skb, ah->auth_data);
104 memcpy(ah->auth_data, ahp->work_icv, ahp->icv_trunc_len);
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));
114 ip_send_check(top_iph);
122 static int ah_input(struct xfrm_state *x, struct sk_buff *skb)
128 struct ip_auth_hdr *ah;
132 if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
135 ah = (struct ip_auth_hdr*)skb->data;
137 ah_hlen = (ah->hdrlen + 2) << 2;
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))
143 if (!pskb_may_pull(skb, ah_hlen))
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))
152 skb->ip_summed = CHECKSUM_NONE;
154 ah = (struct ip_auth_hdr*)skb->data;
157 ihl = skb->data - skb_network_header(skb);
158 memcpy(work_buf, iph, ihl);
164 if (ihl > sizeof(*iph)) {
166 if (ip_clear_mutable_options(iph, &dummy))
170 u8 auth_data[MAX_AH_AUTH_LEN];
172 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
174 err = ah_mac_digest(ahp, skb, ah->auth_data);
178 if (memcmp(ahp->work_icv, auth_data, ahp->icv_trunc_len)) {
179 x->stats.integrity_failed++;
183 ((struct iphdr*)work_buf)->protocol = ah->nexthdr;
184 skb->network_header += ah_hlen;
185 memcpy(skb_network_header(skb), work_buf, ihl);
186 skb->transport_header = skb->network_header;
187 __skb_pull(skb, ah_hlen + ihl);
195 static void ah4_err(struct sk_buff *skb, u32 info)
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;
201 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
202 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
205 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET);
208 printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n",
209 ntohl(ah->spi), ntohl(iph->daddr));
213 static int ah_init_state(struct xfrm_state *x)
215 struct ah_data *ahp = NULL;
216 struct xfrm_algo_desc *aalg_desc;
217 struct crypto_hash *tfm;
225 ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
229 tfm = crypto_alloc_hash(x->aalg->alg_name, 0, CRYPTO_ALG_ASYNC);
234 if (crypto_hash_setkey(tfm, x->aalg->alg_key,
235 (x->aalg->alg_key_len + 7) / 8))
239 * Lookup the algorithm description maintained by xfrm_algo,
240 * verify crypto transform properties, and store information
241 * we need for AH processing. This lookup cannot fail here
242 * after a successful crypto_alloc_hash().
244 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
247 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
248 crypto_hash_digestsize(tfm)) {
249 printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
250 x->aalg->alg_name, crypto_hash_digestsize(tfm),
251 aalg_desc->uinfo.auth.icv_fullbits/8);
255 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
256 ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
258 BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
260 ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL);
264 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len);
265 if (x->props.mode == XFRM_MODE_TUNNEL)
266 x->props.header_len += sizeof(struct iphdr);
273 kfree(ahp->work_icv);
274 crypto_free_hash(ahp->tfm);
280 static void ah_destroy(struct xfrm_state *x)
282 struct ah_data *ahp = x->data;
287 kfree(ahp->work_icv);
288 ahp->work_icv = NULL;
289 crypto_free_hash(ahp->tfm);
295 static struct xfrm_type ah_type =
297 .description = "AH4",
298 .owner = THIS_MODULE,
300 .init_state = ah_init_state,
301 .destructor = ah_destroy,
306 static struct net_protocol ah4_protocol = {
307 .handler = xfrm4_rcv,
308 .err_handler = ah4_err,
312 static int __init ah4_init(void)
314 if (xfrm_register_type(&ah_type, AF_INET) < 0) {
315 printk(KERN_INFO "ip ah init: can't add xfrm type\n");
318 if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) {
319 printk(KERN_INFO "ip ah init: can't add protocol\n");
320 xfrm_unregister_type(&ah_type, AF_INET);
326 static void __exit ah4_fini(void)
328 if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0)
329 printk(KERN_INFO "ip ah close: can't remove protocol\n");
330 if (xfrm_unregister_type(&ah_type, AF_INET) < 0)
331 printk(KERN_INFO "ip ah close: can't remove xfrm type\n");
334 module_init(ah4_init);
335 module_exit(ah4_fini);
336 MODULE_LICENSE("GPL");
337 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH);