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ipsec: ipcomp - Decompress into frags if necessary

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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: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2008-07-25 02:55:33 -07:00 committed by David S. Miller
parent 6fccab671f
commit 7d7e5a60c6
1 changed files with 42 additions and 6 deletions
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48
net/xfrm/xfrm_ipcomp.c
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@ -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)
goto out;
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;
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;
skb->truesize += dlen - plen;
__skb_put(skb, dlen - plen);
skb_copy_to_linear_data(skb, scratch, dlen);
out:
put_cpu();
return err;