On Fri, Sep 04, 2015 at 01:21:06PM +0800, Herbert Xu wrote:

On Mon, Aug 31, 2015 at 03:35:26PM +0800, Herbert Xu wrote:

quoted

I see where the bug came from.  Indeed IPv6 does do fragmentation
but only for tunnel mode.  While your patch added a check that also
affected transport mode.  So in addition to the GSO fix we should
also make the MTU check conditional to tunnel mode.

Here is the patch:

---8<---
ipv6: Fix IPsec pre-encap fragmentation check

The IPv6 IPsec pre-encap path performs fragmentation for tunnel-mode
packets.  That is, we perform fragmentation pre-encap rather than
post-encap.

A check was added later to ensure that proper MTU information is
passed back for locally generated traffic.  Unfortunately this
check was performed on all IPsec packets, including transport-mode
packets.

What's more, the check failed to take GSO into account.

The end result is that transport-mode GSO packets get dropped at
the check.

This patch fixes it by moving the tunnel mode check forward as well
as adding the GSO check.

Fixes: dd767856a36e ("xfrm6: Don't call icmpv6_send on local error")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Applied to the ipsec tree, thanks Herbert!