340 lines
7.6 KiB
C
340 lines
7.6 KiB
C
#include <linux/err.h>
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#include <linux/module.h>
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#include <net/ip.h>
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#include <net/xfrm.h>
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#include <net/ah.h>
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#include <linux/crypto.h>
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#include <linux/pfkeyv2.h>
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#include <net/icmp.h>
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#include <net/protocol.h>
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#include <asm/scatterlist.h>
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/* Clear mutable options and find final destination to substitute
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* into IP header for icv calculation. Options are already checked
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* for validity, so paranoia is not required. */
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static int ip_clear_mutable_options(struct iphdr *iph, u32 *daddr)
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{
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unsigned char * optptr = (unsigned char*)(iph+1);
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int l = iph->ihl*4 - sizeof(struct iphdr);
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int optlen;
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while (l > 0) {
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switch (*optptr) {
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case IPOPT_END:
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return 0;
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case IPOPT_NOOP:
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l--;
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optptr++;
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continue;
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}
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optlen = optptr[1];
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if (optlen<2 || optlen>l)
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return -EINVAL;
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switch (*optptr) {
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case IPOPT_SEC:
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case 0x85: /* Some "Extended Security" crap. */
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case IPOPT_CIPSO:
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case IPOPT_RA:
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case 0x80|21: /* RFC1770 */
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break;
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case IPOPT_LSRR:
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case IPOPT_SSRR:
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if (optlen < 6)
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return -EINVAL;
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memcpy(daddr, optptr+optlen-4, 4);
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/* Fall through */
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default:
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memset(optptr+2, 0, optlen-2);
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}
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l -= optlen;
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optptr += optlen;
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}
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return 0;
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}
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static int ah_output(struct xfrm_state *x, struct sk_buff *skb)
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{
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int err;
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struct iphdr *iph, *top_iph;
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struct ip_auth_hdr *ah;
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struct ah_data *ahp;
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union {
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struct iphdr iph;
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char buf[60];
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} tmp_iph;
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top_iph = skb->nh.iph;
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iph = &tmp_iph.iph;
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iph->tos = top_iph->tos;
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iph->ttl = top_iph->ttl;
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iph->frag_off = top_iph->frag_off;
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if (top_iph->ihl != 5) {
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iph->daddr = top_iph->daddr;
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memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
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err = ip_clear_mutable_options(top_iph, &top_iph->daddr);
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if (err)
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goto error;
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}
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ah = (struct ip_auth_hdr *)((char *)top_iph+top_iph->ihl*4);
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ah->nexthdr = top_iph->protocol;
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top_iph->tos = 0;
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top_iph->tot_len = htons(skb->len);
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top_iph->frag_off = 0;
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top_iph->ttl = 0;
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top_iph->protocol = IPPROTO_AH;
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top_iph->check = 0;
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ahp = x->data;
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ah->hdrlen = (XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
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ahp->icv_trunc_len) >> 2) - 2;
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ah->reserved = 0;
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ah->spi = x->id.spi;
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ah->seq_no = htonl(++x->replay.oseq);
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xfrm_aevent_doreplay(x);
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err = ah_mac_digest(ahp, skb, ah->auth_data);
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if (err)
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goto error;
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memcpy(ah->auth_data, ahp->work_icv, ahp->icv_trunc_len);
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top_iph->tos = iph->tos;
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top_iph->ttl = iph->ttl;
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top_iph->frag_off = iph->frag_off;
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if (top_iph->ihl != 5) {
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top_iph->daddr = iph->daddr;
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memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
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}
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ip_send_check(top_iph);
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err = 0;
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error:
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return err;
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}
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static int ah_input(struct xfrm_state *x, struct sk_buff *skb)
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{
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int ah_hlen;
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int ihl;
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int err = -EINVAL;
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struct iphdr *iph;
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struct ip_auth_hdr *ah;
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struct ah_data *ahp;
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char work_buf[60];
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if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
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goto out;
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ah = (struct ip_auth_hdr*)skb->data;
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ahp = x->data;
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ah_hlen = (ah->hdrlen + 2) << 2;
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if (ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_full_len) &&
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ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len))
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goto out;
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if (!pskb_may_pull(skb, ah_hlen))
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goto out;
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/* We are going to _remove_ AH header to keep sockets happy,
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* so... Later this can change. */
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if (skb_cloned(skb) &&
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pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
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goto out;
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skb->ip_summed = CHECKSUM_NONE;
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ah = (struct ip_auth_hdr*)skb->data;
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iph = skb->nh.iph;
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ihl = skb->data - skb->nh.raw;
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memcpy(work_buf, iph, ihl);
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iph->ttl = 0;
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iph->tos = 0;
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iph->frag_off = 0;
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iph->check = 0;
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if (ihl > sizeof(*iph)) {
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u32 dummy;
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if (ip_clear_mutable_options(iph, &dummy))
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goto out;
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}
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{
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u8 auth_data[MAX_AH_AUTH_LEN];
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memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
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skb_push(skb, ihl);
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err = ah_mac_digest(ahp, skb, ah->auth_data);
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if (err)
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goto out;
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err = -EINVAL;
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if (memcmp(ahp->work_icv, auth_data, ahp->icv_trunc_len)) {
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x->stats.integrity_failed++;
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goto out;
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}
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}
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((struct iphdr*)work_buf)->protocol = ah->nexthdr;
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skb->h.raw = memcpy(skb->nh.raw += ah_hlen, work_buf, ihl);
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__skb_pull(skb, ah_hlen + ihl);
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return 0;
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out:
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return err;
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}
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static void ah4_err(struct sk_buff *skb, u32 info)
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{
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struct iphdr *iph = (struct iphdr*)skb->data;
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struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+(iph->ihl<<2));
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struct xfrm_state *x;
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if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
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skb->h.icmph->code != ICMP_FRAG_NEEDED)
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return;
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x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET);
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if (!x)
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return;
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printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n",
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ntohl(ah->spi), ntohl(iph->daddr));
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xfrm_state_put(x);
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}
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static int ah_init_state(struct xfrm_state *x)
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{
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struct ah_data *ahp = NULL;
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struct xfrm_algo_desc *aalg_desc;
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struct crypto_hash *tfm;
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if (!x->aalg)
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goto error;
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/* null auth can use a zero length key */
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if (x->aalg->alg_key_len > 512)
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goto error;
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if (x->encap)
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goto error;
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ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
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if (ahp == NULL)
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return -ENOMEM;
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ahp->key = x->aalg->alg_key;
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ahp->key_len = (x->aalg->alg_key_len+7)/8;
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tfm = crypto_alloc_hash(x->aalg->alg_name, 0, CRYPTO_ALG_ASYNC);
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if (IS_ERR(tfm))
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goto error;
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ahp->tfm = tfm;
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if (crypto_hash_setkey(tfm, ahp->key, ahp->key_len))
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goto error;
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/*
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* Lookup the algorithm description maintained by xfrm_algo,
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* verify crypto transform properties, and store information
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* we need for AH processing. This lookup cannot fail here
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* after a successful crypto_alloc_hash().
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*/
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aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
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BUG_ON(!aalg_desc);
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if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
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crypto_hash_digestsize(tfm)) {
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printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
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x->aalg->alg_name, crypto_hash_digestsize(tfm),
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aalg_desc->uinfo.auth.icv_fullbits/8);
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goto error;
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}
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ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
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ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
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BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
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ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL);
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if (!ahp->work_icv)
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goto error;
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x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len);
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if (x->props.mode == XFRM_MODE_TUNNEL)
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x->props.header_len += sizeof(struct iphdr);
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x->data = ahp;
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return 0;
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error:
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if (ahp) {
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kfree(ahp->work_icv);
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crypto_free_hash(ahp->tfm);
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kfree(ahp);
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}
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return -EINVAL;
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}
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static void ah_destroy(struct xfrm_state *x)
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{
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struct ah_data *ahp = x->data;
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if (!ahp)
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return;
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kfree(ahp->work_icv);
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ahp->work_icv = NULL;
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crypto_free_hash(ahp->tfm);
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ahp->tfm = NULL;
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kfree(ahp);
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}
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static struct xfrm_type ah_type =
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{
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.description = "AH4",
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.owner = THIS_MODULE,
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.proto = IPPROTO_AH,
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.init_state = ah_init_state,
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.destructor = ah_destroy,
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.input = ah_input,
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.output = ah_output
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};
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static struct net_protocol ah4_protocol = {
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.handler = xfrm4_rcv,
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.err_handler = ah4_err,
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.no_policy = 1,
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};
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static int __init ah4_init(void)
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{
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if (xfrm_register_type(&ah_type, AF_INET) < 0) {
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printk(KERN_INFO "ip ah init: can't add xfrm type\n");
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return -EAGAIN;
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}
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if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) {
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printk(KERN_INFO "ip ah init: can't add protocol\n");
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xfrm_unregister_type(&ah_type, AF_INET);
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return -EAGAIN;
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}
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return 0;
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}
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static void __exit ah4_fini(void)
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{
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if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0)
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printk(KERN_INFO "ip ah close: can't remove protocol\n");
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if (xfrm_unregister_type(&ah_type, AF_INET) < 0)
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printk(KERN_INFO "ip ah close: can't remove xfrm type\n");
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}
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module_init(ah4_init);
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module_exit(ah4_fini);
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MODULE_LICENSE("GPL");
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