Subject: Re: [PATCH] xfrm: add SA information to the offloaded packet

From: Leon Romanovsky <[email-masked]>
Date: Wed, 28 Aug 2024 14:26:19 +0300

On Wed, Aug 28, 2024 at 07:32:47AM +0200, Steffen Klassert wrote:
> On Thu, Aug 22, 2024 at 01:02:52PM -0700, Feng Wang wrote:
> > From: wangfe <[email-masked]>
> > 
> > In packet offload mode, append Security Association (SA) information
> > to each packet, replicating the crypto offload implementation.
> > The XFRM_XMIT flag is set to enable packet to be returned immediately
> > from the validate_xmit_xfrm function, thus aligning with the existing
> > code path for packet offload mode.
> > 
> > This SA info helps HW offload match packets to their correct security
> > policies. The XFRM interface ID is included, which is crucial in setups
> > with multiple XFRM interfaces where source/destination addresses alone
> > can't pinpoint the right policy.
> > 
> > Signed-off-by: wangfe <[email-masked]>
> 
> Applied to ipsec-next, thanks Feng!

Stephen, can you please explain why do you think that this is correct
thing to do?

There are no in-tree any drivers which is using this information, and it
is unclear to me how state is released and it has controversial code
around validity of xfrm_offload() too.

For example:
+		sp->olen++;
+		sp->xvec[sp->len++] = x;
+		xfrm_state_hold(x);
+
+		xo = xfrm_offload(skb);
+		if (!xo) { <--- previous code handled this case perfectly in validate_xmit_xfrm
+			secpath_reset(skb);
+			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
+			kfree_skb(skb);
+			return -EINVAL; <--- xfrm state leak
+		}

Can you please revert/drop this patch for now?

Thanks