Re: [PATCH] net/mlx5: fix GRE flow rule

[Yongseok Koh <yskoh@mellanox.com>]

On Tue, May 22, 2018 at 10:36:43PM -0700, Matan Azrad wrote:
> Hi Yongseok
> 
> From:  Yongseok Koh
> > Creating a flow having pattern from the middle of a packet is allowed. For
> > example,
> > 
> >   testpmd> flow create 0 ingress pattern vxlan vni is 20 / end actions ...
> > 
> > Device can parse GRE header but without proper support from library and
> > firmware (HAVE_IBV_DEVICE_MPLS_SUPPORT), a field in GRE header can't be
> > specified when creating a rule. As a result, the following rule will be
> > interpreted as a wildcard rule, which always matches any packet.
> > 
> >   testpmd> flow create 0 ingress pattern gre / end actions ...
> > Fixes: 96c6c65a10d2 ("net/mlx5: support GRE tunnel flow")
> > Fixes: 1f106da2bf7b ("net/mlx5: support MPLS-in-GRE and MPLS-in-UDP")
> > Cc: stable@dpdk.org
> > 
> > Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
> > ---
> >  drivers/net/mlx5/mlx5_flow.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/net/mlx5/mlx5_flow.c b/drivers/net/mlx5/mlx5_flow.c index
> > 994be05be..526fe6b0e 100644
> > --- a/drivers/net/mlx5/mlx5_flow.c
> > +++ b/drivers/net/mlx5/mlx5_flow.c
> > @@ -330,9 +330,11 @@ static const enum rte_flow_action_type
> > valid_actions[] = {  static const struct mlx5_flow_items mlx5_flow_items[] = {
> >  	[RTE_FLOW_ITEM_TYPE_END] = {
> >  		.items = ITEMS(RTE_FLOW_ITEM_TYPE_ETH,
> > +#ifdef HAVE_IBV_DEVICE_MPLS_SUPPORT
> 
> The GRE item was here even before the MPLSoGRE support

Yes, this bug has existed before adding MPLSoGRE support.

> so I think that this is not the correct fix and even that it can hurt the
> support of GRE for the current customers use it.

How can it hurt? Please clarify.

> Looks like you must specify at least 1 spec in the GRE to apply it correctly
> as you did for VXLAN, Can you try empty vxlan and fully gre (with protocol
> field)?

That's exactly the reason why I'm taking this out. If you look at the code, it
doesn't even set any field for GRE if HAVE_IBV_DEVICE_MPLS_SUPPORT isn't
supported. Thus, it is considered as a wildcard (all-matching) rule. But if it
has HAVE_IBV_DEVICE_MPLS_SUPPORT, such pattern can be allowed.

Having pattern 'vxlan' without vni isn't allowed by mlx5 PMD because zero VNI is
never accepted.

Thanks,
Yongseok

> > +			       RTE_FLOW_ITEM_TYPE_GRE,
> > +#endif
> >  			       RTE_FLOW_ITEM_TYPE_VXLAN,
> > -			       RTE_FLOW_ITEM_TYPE_VXLAN_GPE,
> > -			       RTE_FLOW_ITEM_TYPE_GRE),
> > +			       RTE_FLOW_ITEM_TYPE_VXLAN_GPE),
> >  	},
> >  	[RTE_FLOW_ITEM_TYPE_ETH] = {
> >  		.items = ITEMS(RTE_FLOW_ITEM_TYPE_VLAN,
> 
> 
>