# \[PATCH net-next 5/6\] flow\_dissector: Include GRE keyid in hash computation

- From: Tom Herbert \<hidden\>
- Date: 2015-02-28 03:13:00 
- List: netdev
- Page: https://ratatoskr.run/netdev/2015/02/10979352
- Thread: https://ratatoskr.run/netdev/2015/02/10979346/t.md

```text
If keyid is present include that in hash_extra in flow_keys when
dissecting. This will then be included in hash computation.

Signed-off-by: Tom Herbert <redacted>
---
 net/core/flow_dissector.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index b11eec1..e04946f 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -219,8 +219,21 @@ ipv6:
 			nhoff += 4;
 			if (hdr->flags & GRE_CSUM)
 				nhoff += 4;
-			if (hdr->flags & GRE_KEY)
+			if (hdr->flags & GRE_KEY) {
+				const __be32 *keyid;
+				__be32 _keyid;
+
+				keyid = __skb_header_pointer(skb, nhoff,
+							     sizeof(_keyid),
+							     data, hlen,
+							     &_keyid);
+				if (!keyid)
+					return false;
+
+				flow->hash_extra ^= *keyid;
+
 				nhoff += 4;
+			}
 			if (hdr->flags & GRE_SEQ)
 				nhoff += 4;
 			if (proto == htons(ETH_P_TEB)) {
-- 
2.2.0.rc0.207.ga3a616c
```