1 files changed, 27 insertions, 0 deletions

diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
index 5cebca134585..33a140e15834 100644
--- a/net/ethernet/eth.c
+++ b/net/ethernet/eth.c
@@ -146,6 +146,33 @@ int eth_rebuild_header(struct sk_buff *skb)
 EXPORT_SYMBOL(eth_rebuild_header);
 
 /**
+ * eth_get_headlen - determine the the length of header for an ethernet frame
+ * @data: pointer to start of frame
+ * @len: total length of frame
+ *
+ * Make a best effort attempt to pull the length for all of the headers for
+ * a given frame in a linear buffer.
+ */
+u32 eth_get_headlen(void *data, unsigned int len)
+{
+        const struct ethhdr *eth = (const struct ethhdr *)data;
+        struct flow_keys keys;
+
+        /* this should never happen, but better safe than sorry */
+        if (len < sizeof(*eth))
+                return len;
+
+        /* parse any remaining L2/L3 headers, check for L4 */
+        if (!__skb_flow_dissect(NULL, &keys, data,
+                                eth->h_proto, sizeof(*eth), len))
+                return max_t(u32, keys.thoff, sizeof(*eth));
+
+        /* parse for any L4 headers */
+        return min_t(u32, __skb_get_poff(NULL, data, &keys, len), len);
+}
+EXPORT_SYMBOL(eth_get_headlen);
+
+/**
  * eth_type_trans - determine the packet's protocol ID.
  * @skb: received socket data
  * @dev: receiving network device