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Commit 7d7e5a60 authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
Browse files

ipsec: ipcomp - Decompress into frags if necessary 



When decompressing extremely large packets allocating them through
kmalloc is prone to failure.  Therefore it's better to use page
frags instead.

Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6fccab67

net/xfrm/xfrm_ipcomp.c

+42 −6
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 


#include <linux/crypto.h>

#include <linux/err.h>

#include <linux/gfp.h>

#include <linux/list.h>

#include <linux/module.h>

#include <linux/mutex.h>
@@ -49,6 +50,7 @@ static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb) 
	u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);

	struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);

	int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);

	int len;



	if (err)

		goto out;
@@ -58,13 +60,47 @@ static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb) 
		goto out;

	}



	err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);

	if (err)

	len = dlen - plen;

	if (len > skb_tailroom(skb))

		len = skb_tailroom(skb);



	skb->truesize += len;

	__skb_put(skb, len);



	len += plen;

	skb_copy_to_linear_data(skb, scratch, len);



	while ((scratch += len, dlen -= len) > 0) {

		skb_frag_t *frag;



		err = -EMSGSIZE;

		if (WARN_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS))

			goto out;



	skb->truesize += dlen - plen;

	__skb_put(skb, dlen - plen);

	skb_copy_to_linear_data(skb, scratch, dlen);

		frag = skb_shinfo(skb)->frags + skb_shinfo(skb)->nr_frags;

		frag->page = alloc_page(GFP_ATOMIC);



		err = -ENOMEM;

		if (!frag->page)

			goto out;



		len = PAGE_SIZE;

		if (dlen < len)

			len = dlen;



		memcpy(page_address(frag->page), scratch, len);



		frag->page_offset = 0;

		frag->size = len;

		skb->truesize += len;

		skb->data_len += len;

		skb->len += len;



		skb_shinfo(skb)->nr_frags++;

	}



	err = 0;



out:

	put_cpu();

	return err;