Commit a8db7b2d authored by Florian Westphal's avatar Florian Westphal Committed by Pablo Neira Ayuso
Browse files

netfilter: nf_queue: fix queueing of bridged gro skbs 



When trying to nf_queue GRO/GSO skbs, nf_queue uses skb_gso_segment
to split the skb.

However, if nf_queue is called via bridge netfilter, the mac header
won't be preserved -- packets will thus contain a bogus mac header.

Fix this by setting skb->data to the mac header when skb->nf_bridge
is set and restoring skb->data afterwards for all segments.

Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent e0aac52e

net/netfilter/nf_queue.c

+32 −8
Original line number Diff line number Diff line
@@ -203,6 +203,27 @@ err: 
	return status;

}



#ifdef CONFIG_BRIDGE_NETFILTER

/* When called from bridge netfilter, skb->data must point to MAC header

 * before calling skb_gso_segment(). Else, original MAC header is lost

 * and segmented skbs will be sent to wrong destination.

 */

static void nf_bridge_adjust_skb_data(struct sk_buff *skb)

{

	if (skb->nf_bridge)

		__skb_push(skb, skb->network_header - skb->mac_header);

}



static void nf_bridge_adjust_segmented_data(struct sk_buff *skb)

{

	if (skb->nf_bridge)

		__skb_pull(skb, skb->network_header - skb->mac_header);

}

#else

#define nf_bridge_adjust_skb_data(s) do {} while (0)

#define nf_bridge_adjust_segmented_data(s) do {} while (0)

#endif



int nf_queue(struct sk_buff *skb,

	     struct list_head *elem,

	     u_int8_t pf, unsigned int hook,
@@ -212,7 +233,7 @@ int nf_queue(struct sk_buff *skb, 
	     unsigned int queuenum)

{

	struct sk_buff *segs;

	int err;

	int err = -EINVAL;

	unsigned int queued;



	if (!skb_is_gso(skb))
@@ -228,23 +249,25 @@ int nf_queue(struct sk_buff *skb, 
		break;

	}



	nf_bridge_adjust_skb_data(skb);

	segs = skb_gso_segment(skb, 0);

	/* Does not use PTR_ERR to limit the number of error codes that can be

	 * returned by nf_queue.  For instance, callers rely on -ECANCELED to mean

	 * 'ignore this hook'.

	 */

	if (IS_ERR(segs))

		return -EINVAL;



		goto out_err;

	queued = 0;

	err = 0;

	do {

		struct sk_buff *nskb = segs->next;



		segs->next = NULL;

		if (err == 0)

		if (err == 0) {

			nf_bridge_adjust_segmented_data(segs);

			err = __nf_queue(segs, elem, pf, hook, indev,

					   outdev, okfn, queuenum);

		}

		if (err == 0)

			queued++;

		else
@@ -252,11 +275,12 @@ int nf_queue(struct sk_buff *skb, 
		segs = nskb;

	} while (segs);



	/* also free orig skb if only some segments were queued */

	if (unlikely(err && queued))

		err = 0;

	if (err == 0)

	if (queued) {

		kfree_skb(skb);

		return 0;

	}

  out_err:

	nf_bridge_adjust_segmented_data(skb);

	return err;

}

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