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authorRusty Russell <rusty@rustcorp.com.au>2008-02-04 23:49:54 -0500
committerRusty Russell <rusty@rustcorp.com.au>2008-02-04 23:49:56 +1100
commitf35d9d8aae08940b7fdd1bb8110619da2ece6b28 (patch)
tree562d8d7a6583d0a0750ec8d996026b73e8315421 /net
parent9135f1901ee6449dfe338adf6e40e9c2025b8150 (diff)
downloadlinux-linaro-stable-f35d9d8aae08940b7fdd1bb8110619da2ece6b28.tar.gz
virtio: Implement skb_partial_csum_set, for setting partial csums on untrusted packets.
Use it in virtio_net (replacing buggy version there), it's also going to be used by TAP for partial csum support. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/skbuff.c29
1 files changed, 29 insertions, 0 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 98420f9c4b6d..4e354221ec23 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2461,6 +2461,34 @@ int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
return elt;
}
+/**
+ * skb_partial_csum_set - set up and verify partial csum values for packet
+ * @skb: the skb to set
+ * @start: the number of bytes after skb->data to start checksumming.
+ * @off: the offset from start to place the checksum.
+ *
+ * For untrusted partially-checksummed packets, we need to make sure the values
+ * for skb->csum_start and skb->csum_offset are valid so we don't oops.
+ *
+ * This function checks and sets those values and skb->ip_summed: if this
+ * returns false you should drop the packet.
+ */
+bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
+{
+ if (unlikely(start > skb->len - 2) ||
+ unlikely((int)start + off > skb->len - 2)) {
+ if (net_ratelimit())
+ printk(KERN_WARNING
+ "bad partial csum: csum=%u/%u len=%u\n",
+ start, off, skb->len);
+ return false;
+ }
+ skb->ip_summed = CHECKSUM_PARTIAL;
+ skb->csum_start = skb_headroom(skb) + start;
+ skb->csum_offset = off;
+ return true;
+}
+
EXPORT_SYMBOL(___pskb_trim);
EXPORT_SYMBOL(__kfree_skb);
EXPORT_SYMBOL(kfree_skb);
@@ -2497,3 +2525,4 @@ EXPORT_SYMBOL(skb_append_datato_frags);
EXPORT_SYMBOL_GPL(skb_to_sgvec);
EXPORT_SYMBOL_GPL(skb_cow_data);
+EXPORT_SYMBOL_GPL(skb_partial_csum_set);