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/*

 * xfrm_output.c - Common IPsec encapsulation code.

 *

 * Copyright (c) 2007 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/errno.h>

#include <linux/module.h>

#include <linux/netdevice.h>

#include <linux/skbuff.h>

#include <linux/spinlock.h>

#include <net/dst.h>

#include <net/xfrm.h>

static int xfrm_state_check_space(struct xfrm_state *x, struct sk_buff *skb)

{

        int nhead = x->props.header_len + LL_RESERVED_SPACE(skb->dst->dev)

                - skb_headroom(skb);

        if (nhead > 0)

                return pskb_expand_head(skb, nhead, 0, GFP_ATOMIC);

        /* Check tail too... */

        return 0;

}

static int xfrm_state_check(struct xfrm_state *x, struct sk_buff *skb)

{

        int err = xfrm_state_check_expire(x);

        if (err < 0)

                goto err;

        err = xfrm_state_check_space(x, skb);

err:

        return err;

}

int xfrm_output(struct sk_buff *skb)

{

        struct dst_entry *dst = skb->dst;

        struct xfrm_state *x = dst->xfrm;

        int err;

        if (skb->ip_summed == CHECKSUM_PARTIAL) {

                err = skb_checksum_help(skb);

                if (err)

                        goto error_nolock;

        }

        do {

                spin_lock_bh(&x->lock);

                err = xfrm_state_check(x, skb);

                if (err)

                        goto error;

                if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {

                        XFRM_SKB_CB(skb)->seq = ++x->replay.oseq;

                        if (xfrm_aevent_is_on())

                                xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);

                }

                err = x->outer_mode->output(x, skb);

                if (err)

                        goto error;

                x->curlft.bytes += skb->len;

                x->curlft.packets++;

                spin_unlock_bh(&x->lock);

                err = x->type->output(x, skb);

                if (err)

                        goto error_nolock;

                if (!(skb->dst = dst_pop(dst))) {

                        err = -EHOSTUNREACH;

                        goto error_nolock;

                }

                dst = skb->dst;

                x = dst->xfrm;

        } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));

        err = 0;

error_nolock:

        return err;

error:

        spin_unlock_bh(&x->lock);

        goto error_nolock;

}

EXPORT_SYMBOL_GPL(xfrm_output);