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: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -17,6 +17,7 @@
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#include <linux/crypto.h>
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#include <linux/err.h>
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#include <linux/gfp.h>
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#include <linux/list.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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@ -49,6 +50,7 @@ static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
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u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
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struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
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int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
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int len;
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if (err)
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goto out;
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@ -58,13 +60,47 @@ static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
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goto out;
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}
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err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
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if (err)
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goto out;
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len = dlen - plen;
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if (len > skb_tailroom(skb))
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len = skb_tailroom(skb);
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skb->truesize += len;
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__skb_put(skb, len);
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len += plen;
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skb_copy_to_linear_data(skb, scratch, len);
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while ((scratch += len, dlen -= len) > 0) {
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skb_frag_t *frag;
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err = -EMSGSIZE;
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if (WARN_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS))
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goto out;
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frag = skb_shinfo(skb)->frags + skb_shinfo(skb)->nr_frags;
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frag->page = alloc_page(GFP_ATOMIC);
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err = -ENOMEM;
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if (!frag->page)
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goto out;
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len = PAGE_SIZE;
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if (dlen < len)
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len = dlen;
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memcpy(page_address(frag->page), scratch, len);
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frag->page_offset = 0;
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frag->size = len;
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skb->truesize += len;
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skb->data_len += len;
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skb->len += len;
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skb_shinfo(skb)->nr_frags++;
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}
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err = 0;
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skb->truesize += dlen - plen;
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__skb_put(skb, dlen - plen);
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skb_copy_to_linear_data(skb, scratch, dlen);
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out:
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put_cpu();
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return err;
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