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

From: Leon Romanovsky <[email-masked]>
Date: Tue, 18 Jul 2023 12:52:42 +0300

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 <[email-masked]>
> ---
>  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)) {
> -- 
> 
>