Re: [PATCH] xfrm: Allow ESP over UDP in packet offload mode

[Ilia Lin]

Hi Leon,

Indeed the policy check is checking the sec_path lags set after
decapsulation, but this has nothing to do with UDP encapsulation, the
driver will set them anyway.
Regarding the driver support, each driver may restrict NAT-T support
in their state_add callback, so in common code it may stay allowed.

Thanks,
Ilia

BR,
Ilia Lin



On Tue, Jul 18, 2023 at 12:53 PM Leon Romanovsky <leonro@xxxxxxxxxx> wrote:
>
> On Tue, Jul 18, 2023 at 12:24:05PM +0300, Ilia Lin wrote:
> > The ESP encapsulation is not supported only in crypto mode.
> > In packet offload mode, the RX is bypassing the XFRM,
> > so we can enable the encapsulation.
>
> It is not accurate. RX is bypassed after XFRM validated packet to ensure
> that it was really handled by HW.
>
> However, this patch should come with relevant driver code which should
> support ESP over UDP. You can see it here:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git/log/?h=xfrm-next
>  xfrm: Support UDP encapsulation in packet offload mode
>  net/mlx5e: Support IPsec NAT-T functionality
>  net/mlx5e: Check for IPsec NAT-T support
>  net/mlx5: Add relevant capabilities bits to support NAT-T
>
> Thanks
>
> >
> > Signed-off-by: Ilia Lin <ilia.lin@xxxxxxxxxx>
> > ---
> >  net/xfrm/xfrm_device.c | 7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/net/xfrm/xfrm_device.c b/net/xfrm/xfrm_device.c
> > index 4aff76c6f12e0..3018468d97662 100644
> > --- a/net/xfrm/xfrm_device.c
> > +++ b/net/xfrm/xfrm_device.c
> > @@ -246,8 +246,10 @@ int xfrm_dev_state_add(struct net *net, struct xfrm_state *x,
> >               return -EINVAL;
> >       }
> >
> > -     /* We don't yet support UDP encapsulation and TFC padding. */
> > -     if (x->encap || x->tfcpad) {
> > +     is_packet_offload = xuo->flags & XFRM_OFFLOAD_PACKET;
> > +
> > +     /* We don't yet support UDP encapsulation except full mode and TFC padding. */
> > +     if ((!is_packet_offload && x->encap) || x->tfcpad) {
> >               NL_SET_ERR_MSG(extack, "Encapsulation and TFC padding can't be offloaded");
> >               return -EINVAL;
> >       }
> > @@ -258,7 +260,6 @@ int xfrm_dev_state_add(struct net *net, struct xfrm_state *x,
> >               return -EINVAL;
> >       }
> >
> > -     is_packet_offload = xuo->flags & XFRM_OFFLOAD_PACKET;
> >       dev = dev_get_by_index(net, xuo->ifindex);
> >       if (!dev) {
> >               if (!(xuo->flags & XFRM_OFFLOAD_INBOUND)) {
> > --
> >
> >