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>

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>
Herbert Xu · David S. Miller
1 parent 6fccab671f
Showing 1 changed file with 42 additions and 6 deletions Side-by-side Diff
net/xfrm/xfrm_ipcomp.c
@@ -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 @@
 	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 @@
 		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 += dlen - plen;
-	__skb_put(skb, dlen - plen);
-	skb_copy_to_linear_data(skb, scratch, dlen);
+	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;
+
 out:
 	put_cpu();
 	return err;
...	...	@@ -17,6 +17,7 @@
17	17
18	18	#include <linux/crypto.h>
19	19	#include <linux/err.h>
	20	+#include <linux/gfp.h>
20	21	#include <linux/list.h>
21	22	#include <linux/module.h>
22	23	#include <linux/mutex.h>
...	...	@@ -49,6 +50,7 @@
49	50	u8 scratch = per_cpu_ptr(ipcomp_scratches, cpu);
50	51	struct crypto_comp tfm = per_cpu_ptr(ipcd->tfms, cpu);
51	52	int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
	53	+ int len;
52	54
53	55	if (err)
54	56	goto out;
55	57
...	...	@@ -58,13 +60,47 @@
58	60	goto out;
59	61	}
60	62
61		- err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
62		- if (err)
63		- goto out;
	63	+ len = dlen - plen;
	64	+ if (len > skb_tailroom(skb))
	65	+ len = skb_tailroom(skb);
64	66
65		- skb->truesize += dlen - plen;
66		- __skb_put(skb, dlen - plen);
67		- skb_copy_to_linear_data(skb, scratch, dlen);
	67	+ skb->truesize += len;
	68	+ __skb_put(skb, len);
	69	+
	70	+ len += plen;
	71	+ skb_copy_to_linear_data(skb, scratch, len);
	72	+
	73	+ while ((scratch += len, dlen -= len) > 0) {
	74	+ skb_frag_t *frag;
	75	+
	76	+ err = -EMSGSIZE;
	77	+ if (WARN_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS))
	78	+ goto out;
	79	+
	80	+ frag = skb_shinfo(skb)->frags + skb_shinfo(skb)->nr_frags;
	81	+ frag->page = alloc_page(GFP_ATOMIC);
	82	+
	83	+ err = -ENOMEM;
	84	+ if (!frag->page)
	85	+ goto out;
	86	+
	87	+ len = PAGE_SIZE;
	88	+ if (dlen < len)
	89	+ len = dlen;
	90	+
	91	+ memcpy(page_address(frag->page), scratch, len);
	92	+
	93	+ frag->page_offset = 0;
	94	+ frag->size = len;
	95	+ skb->truesize += len;
	96	+ skb->data_len += len;
	97	+ skb->len += len;
	98	+
	99	+ skb_shinfo(skb)->nr_frags++;
	100	+ }
	101	+
	102	+ err = 0;
	103	+
68	104	out:
69	105	put_cpu();
70	106	return err;