netdev - [net PATCH] net: Copy inner L3 and L4 headers as unaligned on GRE TEB

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Message-ID: <20160209141234.19305.82202.stgit@localhost.localdomain>
Date:	Tue, 09 Feb 2016 06:14:43 -0800
From:	Alexander Duyck <aduyck@...antis.com>
To:	netdev@...r.kernel.org, alexander.duyck@...il.com
Cc:	tom@...bertland.com, davem@...emloft.net
Subject: [net PATCH] net: Copy inner L3 and L4 headers as unaligned on GRE
 TEB

This patch corrects the unaligned accesses seen on GRE TEB tunnels when
generating hash keys.  Specifically what this patch does is make it so that
we force the use of skb_copy_bits when the GRE inner headers will be
unaligned due to NET_IP_ALIGNED being a non-zero value.

Signed-off-by: Alexander Duyck <aduyck@...antis.com>
---

I don't have the ability to test it but this should fix flow dissector for
GRE TEB tunnels traffic seen on architectures that require network and
transport headers to be 4 byte aligned.

 net/core/flow_dissector.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 699b2c415cb0..9c181ba7263e 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -402,6 +402,13 @@ ip_proto_again:
 				goto out_bad;
 			proto = eth->h_proto;
 			nhoff += sizeof(*eth);
+
+			/* Cap headers that we access via pointers at the
+			 * end of the Ethernet header as our maximum alignment
+			 * at that point is only 2 bytes.
+			 */
+			if (NET_IP_ALIGN)
+				hlen = nhoff;
 		}

 		key_control->flags |= FLOW_DIS_ENCAPSULATION;