/* * xfrm6_output.c - Common IPsec encapsulation code for IPv6. * Copyright (C) 2002 USAGI/WIDE Project * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include <linux/compiler.h> #include <linux/skbuff.h> #include <linux/spinlock.h> #include <linux/icmpv6.h> #include <linux/netfilter_ipv6.h> #include <net/dsfield.h> #include <net/inet_ecn.h> #include <net/ipv6.h> #include <net/xfrm.h> /* Add encapsulation header. * * In transport mode, the IP header and mutable extension headers will be moved * forward to make space for the encapsulation header. * * In tunnel mode, the top IP header will be constructed per RFC 2401. * The following fields in it shall be filled in by x->type->output: * payload_len * * On exit, skb->h will be set to the start of the encapsulation header to be * filled in by x->type->output and skb->nh will be set to the nextheader field * of the extension header directly preceding the encapsulation header, or in * its absence, that of the top IP header. The value of skb->data will always * point to the top IP header. */ static void xfrm6_encap(struct sk_buff *skb) { struct dst_entry *dst = skb->dst; struct xfrm_state *x = dst->xfrm; struct ipv6hdr *iph, *top_iph; int dsfield; skb_push(skb, x->props.header_len); iph = skb->nh.ipv6h; if (!x->props.mode) { u8 *prevhdr; int hdr_len; hdr_len = ip6_find_1stfragopt(skb, &prevhdr); skb->nh.raw = prevhdr - x->props.header_len; skb->h.raw = skb->data + hdr_len; memmove(skb->data, iph, hdr_len); return; } skb->nh.raw = skb->data; top_iph = skb->nh.ipv6h; skb->nh.raw = &top_iph->nexthdr; skb->h.ipv6h = top_iph + 1; top_iph->version = 6; top_iph->priority = iph->priority; top_iph->flow_lbl[0] = iph->flow_lbl[0]; top_iph->flow_lbl[1] = iph->flow_lbl[1]; top_iph->flow_lbl[2] = iph->flow_lbl[2]; dsfield = ipv6_get_dsfield(top_iph); dsfield = INET_ECN_encapsulate(dsfield, dsfield); if (x->props.flags & XFRM_STATE_NOECN) dsfield &= ~INET_ECN_MASK; ipv6_change_dsfield(top_iph, 0, dsfield); top_iph->nexthdr = IPPROTO_IPV6; top_iph->hop_limit = dst_metric(dst->child, RTAX_HOPLIMIT); ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr); ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr); } static int xfrm6_tunnel_check_size(struct sk_buff *skb) { int mtu, ret = 0; struct dst_entry *dst = skb->dst; mtu = dst_mtu(dst); if (mtu < IPV6_MIN_MTU) mtu = IPV6_MIN_MTU; if (skb->len > mtu) { skb->dev = dst->dev; icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev); ret = -EMSGSIZE; } return ret; } static int xfrm6_output_one(struct sk_buff *skb) { struct dst_entry *dst = skb->dst; struct xfrm_state *x = dst->xfrm; int err; if (skb->ip_summed == CHECKSUM_HW) { err = skb_checksum_help(skb, 0); if (err) goto error_nolock; } if (x->props.mode) { err = xfrm6_tunnel_check_size(skb); if (err) goto error_nolock; } do { spin_lock_bh(&x->lock); err = xfrm_state_check(x, skb); if (err) goto error; xfrm6_encap(skb); err = x->type->output(x, skb); if (err) goto error; x->curlft.bytes += skb->len; x->curlft.packets++; spin_unlock_bh(&x->lock); skb->nh.raw = skb->data; if (!(skb->dst = dst_pop(dst))) { err = -EHOSTUNREACH; goto error_nolock; } dst = skb->dst; x = dst->xfrm; } while (x && !x->props.mode); IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED; err = 0; out_exit: return err; error: spin_unlock_bh(&x->lock); error_nolock: kfree_skb(skb); goto out_exit; } static int xfrm6_output_finish(struct sk_buff *skb) { int err; while (likely((err = xfrm6_output_one(skb)) == 0)) { nf_reset(skb); err = nf_hook(PF_INET6, NF_IP6_LOCAL_OUT, &skb, NULL, skb->dst->dev, dst_output); if (unlikely(err != 1)) break; if (!skb->dst->xfrm) return dst_output(skb); err = nf_hook(PF_INET6, NF_IP6_POST_ROUTING, &skb, NULL, skb->dst->dev, xfrm6_output_finish); if (unlikely(err != 1)) break; } return err; } int xfrm6_output(struct sk_buff *skb) { return NF_HOOK(PF_INET6, NF_IP6_POST_ROUTING, skb, NULL, skb->dst->dev, xfrm6_output_finish); }