xfrm6_output.c
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/*
* 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/skbuff.h>
#include <linux/spinlock.h>
#include <linux/icmpv6.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;
}
int xfrm6_output(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;
}
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;
}
err = NET_XMIT_BYPASS;
out_exit:
return err;
error:
spin_unlock_bh(&x->lock);
error_nolock:
kfree_skb(skb);
goto out_exit;
}