#include <linux/err.h> #include <linux/module.h> #include <net/ip.h> #include <net/xfrm.h> #include <net/ah.h> #include <linux/crypto.h> #include <linux/pfkeyv2.h> #include <linux/spinlock.h> #include <net/icmp.h> #include <net/protocol.h> /* Clear mutable options and find final destination to substitute * into IP header for icv calculation. Options are already checked * for validity, so paranoia is not required. */ static int ip_clear_mutable_options(struct iphdr *iph, __be32 *daddr) { unsigned char * optptr = (unsigned char*)(iph+1); int l = iph->ihl*4 - sizeof(struct iphdr); int optlen; while (l > 0) { switch (*optptr) { case IPOPT_END: return 0; case IPOPT_NOOP: l--; optptr++; continue; } optlen = optptr[1]; if (optlen<2 || optlen>l) return -EINVAL; switch (*optptr) { case IPOPT_SEC: case 0x85: /* Some "Extended Security" crap. */ case IPOPT_CIPSO: case IPOPT_RA: case 0x80|21: /* RFC1770 */ break; case IPOPT_LSRR: case IPOPT_SSRR: if (optlen < 6) return -EINVAL; memcpy(daddr, optptr+optlen-4, 4); /* Fall through */ default: memset(optptr, 0, optlen); } l -= optlen; optptr += optlen; } return 0; } static int ah_output(struct xfrm_state *x, struct sk_buff *skb) { int err; struct iphdr *iph, *top_iph; struct ip_auth_hdr *ah; struct ah_data *ahp; union { struct iphdr iph; char buf[60]; } tmp_iph; skb_push(skb, -skb_network_offset(skb)); top_iph = ip_hdr(skb); iph = &tmp_iph.iph; iph->tos = top_iph->tos; iph->ttl = top_iph->ttl; iph->frag_off = top_iph->frag_off; if (top_iph->ihl != 5) { iph->daddr = top_iph->daddr; memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); err = ip_clear_mutable_options(top_iph, &top_iph->daddr); if (err) goto error; } ah = ip_auth_hdr(skb); ah->nexthdr = *skb_mac_header(skb); *skb_mac_header(skb) = IPPROTO_AH; top_iph->tos = 0; top_iph->tot_len = htons(skb->len); top_iph->frag_off = 0; top_iph->ttl = 0; top_iph->check = 0; ahp = x->data; ah->hdrlen = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2; ah->reserved = 0; ah->spi = x->id.spi; ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output); spin_lock_bh(&x->lock); err = ah_mac_digest(ahp, skb, ah->auth_data); memcpy(ah->auth_data, ahp->work_icv, ahp->icv_trunc_len); spin_unlock_bh(&x->lock); if (err) goto error; top_iph->tos = iph->tos; top_iph->ttl = iph->ttl; top_iph->frag_off = iph->frag_off; if (top_iph->ihl != 5) { top_iph->daddr = iph->daddr; memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); } err = 0; error: return err; } static int ah_input(struct xfrm_state *x, struct sk_buff *skb) { int ah_hlen; int ihl; int nexthdr; int err = -EINVAL; struct iphdr *iph; struct ip_auth_hdr *ah; struct ah_data *ahp; char work_buf[60]; if (!pskb_may_pull(skb, sizeof(*ah))) goto out; ah = (struct ip_auth_hdr *)skb->data; ahp = x->data; nexthdr = ah->nexthdr; ah_hlen = (ah->hdrlen + 2) << 2; if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) && ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len)) goto out; if (!pskb_may_pull(skb, ah_hlen)) goto out; /* We are going to _remove_ AH header to keep sockets happy, * so... Later this can change. */ if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) goto out; skb->ip_summed = CHECKSUM_NONE; ah = (struct ip_auth_hdr *)skb->data; iph = ip_hdr(skb); ihl = skb->data - skb_network_header(skb); memcpy(work_buf, iph, ihl); iph->ttl = 0; iph->tos = 0; iph->frag_off = 0; iph->check = 0; if (ihl > sizeof(*iph)) { __be32 dummy; if (ip_clear_mutable_options(iph, &dummy)) goto out; } spin_lock(&x->lock); { u8 auth_data[MAX_AH_AUTH_LEN]; memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len); skb_push(skb, ihl); err = ah_mac_digest(ahp, skb, ah->auth_data); if (err) goto unlock; if (memcmp(ahp->work_icv, auth_data, ahp->icv_trunc_len)) err = -EBADMSG; } unlock: spin_unlock(&x->lock); if (err) goto out; skb->network_header += ah_hlen; memcpy(skb_network_header(skb), work_buf, ihl); skb->transport_header = skb->network_header; __skb_pull(skb, ah_hlen + ihl); return nexthdr; out: return err; } static void ah4_err(struct sk_buff *skb, u32 info) { struct net *net = dev_net(skb->dev); struct iphdr *iph = (struct iphdr *)skb->data; struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+(iph->ihl<<2)); struct xfrm_state *x; if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH || icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) return; x = xfrm_state_lookup(net, (xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET); if (!x) return; printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n", ntohl(ah->spi), ntohl(iph->daddr)); xfrm_state_put(x); } static int ah_init_state(struct xfrm_state *x) { struct ah_data *ahp = NULL; struct xfrm_algo_desc *aalg_desc; struct crypto_hash *tfm; if (!x->aalg) goto error; if (x->encap) goto error; ahp = kzalloc(sizeof(*ahp), GFP_KERNEL); if (ahp == NULL) return -ENOMEM; tfm = crypto_alloc_hash(x->aalg->alg_name, 0, CRYPTO_ALG_ASYNC); if (IS_ERR(tfm)) goto error; ahp->tfm = tfm; if (crypto_hash_setkey(tfm, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8)) goto error; /* * Lookup the algorithm description maintained by xfrm_algo, * verify crypto transform properties, and store information * we need for AH processing. This lookup cannot fail here * after a successful crypto_alloc_hash(). */ aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); BUG_ON(!aalg_desc); if (aalg_desc->uinfo.auth.icv_fullbits/8 != crypto_hash_digestsize(tfm)) { printk(KERN_INFO "AH: %s digestsize %u != %hu\n", x->aalg->alg_name, crypto_hash_digestsize(tfm), aalg_desc->uinfo.auth.icv_fullbits/8); goto error; } ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN); ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL); if (!ahp->work_icv) goto error; x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len); if (x->props.mode == XFRM_MODE_TUNNEL) x->props.header_len += sizeof(struct iphdr); x->data = ahp; return 0; error: if (ahp) { kfree(ahp->work_icv); crypto_free_hash(ahp->tfm); kfree(ahp); } return -EINVAL; } static void ah_destroy(struct xfrm_state *x) { struct ah_data *ahp = x->data; if (!ahp) return; kfree(ahp->work_icv); crypto_free_hash(ahp->tfm); kfree(ahp); } static const struct xfrm_type ah_type = { .description = "AH4", .owner = THIS_MODULE, .proto = IPPROTO_AH, .flags = XFRM_TYPE_REPLAY_PROT, .init_state = ah_init_state, .destructor = ah_destroy, .input = ah_input, .output = ah_output }; static struct net_protocol ah4_protocol = { .handler = xfrm4_rcv, .err_handler = ah4_err, .no_policy = 1, .netns_ok = 1, }; static int __init ah4_init(void) { if (xfrm_register_type(&ah_type, AF_INET) < 0) { printk(KERN_INFO "ip ah init: can't add xfrm type\n"); return -EAGAIN; } if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) { printk(KERN_INFO "ip ah init: can't add protocol\n"); xfrm_unregister_type(&ah_type, AF_INET); return -EAGAIN; } return 0; } static void __exit ah4_fini(void) { if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0) printk(KERN_INFO "ip ah close: can't remove protocol\n"); if (xfrm_unregister_type(&ah_type, AF_INET) < 0) printk(KERN_INFO "ip ah close: can't remove xfrm type\n"); } module_init(ah4_init); module_exit(ah4_fini); MODULE_LICENSE("GPL"); MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH);