xfrm_output.c 4.5 KB
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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>
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#include <linux/netfilter.h>
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#include <linux/skbuff.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
#include <net/dst.h>
#include <net/xfrm.h>

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static int xfrm_output2(struct sk_buff *skb);

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static int xfrm_state_check_space(struct xfrm_state *x, struct sk_buff *skb)
{
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	struct dst_entry *dst = skb_dst(skb);
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	int nhead = dst->header_len + LL_RESERVED_SPACE(dst->dev)
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		- skb_headroom(skb);
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	int ntail = dst->dev->needed_tailroom - skb_tailroom(skb);
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	if (nhead <= 0) {
		if (ntail <= 0)
			return 0;
		nhead = 0;
	} else if (ntail < 0)
		ntail = 0;

	return pskb_expand_head(skb, nhead, ntail, GFP_ATOMIC);
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}

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static int xfrm_output_one(struct sk_buff *skb, int err)
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{
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	struct dst_entry *dst = skb_dst(skb);
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	struct xfrm_state *x = dst->xfrm;
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	struct net *net = xs_net(x);
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	if (err <= 0)
		goto resume;
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	do {
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		err = xfrm_state_check_space(x, skb);
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		if (err) {
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			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
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			goto error_nolock;
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		}
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		err = x->outer_mode->output(x, skb);
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		if (err) {
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			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
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			goto error_nolock;
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		}
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		spin_lock_bh(&x->lock);
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		err = xfrm_state_check_expire(x);
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		if (err) {
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			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
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			goto error;
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		}
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		if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
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			XFRM_SKB_CB(skb)->seq.output = ++x->replay.oseq;
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			if (unlikely(x->replay.oseq == 0)) {
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				XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
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				x->replay.oseq--;
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				xfrm_audit_state_replay_overflow(x, skb);
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				err = -EOVERFLOW;
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				goto error;
			}
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			if (xfrm_aevent_is_on(net))
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				xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
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		}

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

		spin_unlock_bh(&x->lock);

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		err = x->type->output(x, skb);
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		if (err == -EINPROGRESS)
			goto out_exit;
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resume:
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		if (err) {
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			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
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			goto error_nolock;
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		}
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		dst = dst_pop(dst);
		if (!dst) {
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			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
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			err = -EHOSTUNREACH;
			goto error_nolock;
		}
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		skb_dst_set(skb, dst);
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		x = dst->xfrm;
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	} while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
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	err = 0;

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out_exit:
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	return err;
error:
	spin_unlock_bh(&x->lock);
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error_nolock:
	kfree_skb(skb);
	goto out_exit;
}

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int xfrm_output_resume(struct sk_buff *skb, int err)
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{
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	while (likely((err = xfrm_output_one(skb, err)) == 0)) {
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		nf_reset(skb);

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		err = skb_dst(skb)->ops->local_out(skb);
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		if (unlikely(err != 1))
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			goto out;
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		if (!skb_dst(skb)->xfrm)
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			return dst_output(skb);

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		err = nf_hook(skb_dst(skb)->ops->family,
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			      NF_INET_POST_ROUTING, skb,
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			      NULL, skb_dst(skb)->dev, xfrm_output2);
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		if (unlikely(err != 1))
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			goto out;
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	}

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	if (err == -EINPROGRESS)
		err = 0;

out:
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	return err;
}
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EXPORT_SYMBOL_GPL(xfrm_output_resume);
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static int xfrm_output2(struct sk_buff *skb)
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{
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	return xfrm_output_resume(skb, 1);
}
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static int xfrm_output_gso(struct sk_buff *skb)
{
	struct sk_buff *segs;
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	segs = skb_gso_segment(skb, 0);
	kfree_skb(skb);
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	if (IS_ERR(segs))
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		return PTR_ERR(segs);

	do {
		struct sk_buff *nskb = segs->next;
		int err;

		segs->next = NULL;
		err = xfrm_output2(segs);

		if (unlikely(err)) {
			while ((segs = nskb)) {
				nskb = segs->next;
				segs->next = NULL;
				kfree_skb(segs);
			}
			return err;
		}

		segs = nskb;
	} while (segs);

	return 0;
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}
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int xfrm_output(struct sk_buff *skb)
{
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	struct net *net = dev_net(skb_dst(skb)->dev);
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	int err;

	if (skb_is_gso(skb))
		return xfrm_output_gso(skb);

	if (skb->ip_summed == CHECKSUM_PARTIAL) {
		err = skb_checksum_help(skb);
		if (err) {
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			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
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			kfree_skb(skb);
			return err;
		}
	}

	return xfrm_output2(skb);
}
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int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
{
	struct xfrm_mode *inner_mode;
	if (x->sel.family == AF_UNSPEC)
		inner_mode = xfrm_ip2inner_mode(x,
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				xfrm_af2proto(skb_dst(skb)->ops->family));
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	else
		inner_mode = x->inner_mode;

	if (inner_mode == NULL)
		return -EAFNOSUPPORT;
	return inner_mode->afinfo->extract_output(x, skb);
}

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EXPORT_SYMBOL_GPL(xfrm_output);
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EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);