Re: [PATCH net v3 2/2] udp_offload: Set encapsulation before inner completes.

From: David Miller
Date: Fri May 06 2016 - 18:25:54 EST

From: Jarno Rajahalme <jarno@xxxxxxx>
Date: Tue, 3 May 2016 16:10:21 -0700

> UDP tunnel segmentation code relies on the inner offsets being set for
> an UDP tunnel GSO packet, but the inner *_complete() functions will
> set the inner offsets only if 'encapsulation' is set before calling
> them. Currently, udp_gro_complete() sets 'encapsulation' only after
> the inner *_complete() functions are done. This causes the inner
> offsets having invalid values after udp_gro_complete() returns, which
> in turn will make it impossible to properly segment the packet in case
> it needs to be forwarded, which would be visible to the user either as
> invalid packets being sent or as packet loss.
> This patch fixes this by setting skb's 'encapsulation' in
> udp_gro_complete() before calling into the inner complete functions,
> and by making each possible UDP tunnel gro_complete() callback set the
> inner_mac_header to the beginning of the tunnel payload.
> Signed-off-by: Jarno Rajahalme <jarno@xxxxxxx>
> ---
> v3: Added setting inner_mac_header from all possible callbacks to cover
> cases where there is no inner mac header.