netdev - Re: [PATCH ipsec-next] net: xfrm: allow clearing socket xfrm policies.

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Date:   Fri, 1 Dec 2017 06:45:13 +0100
From:   Steffen Klassert <steffen.klassert@...unet.com>
To:     Lorenzo Colitti <lorenzo@...gle.com>
CC:     <netdev@...r.kernel.org>, <zenczykowski@...il.com>,
        <nharold@...gle.com>
Subject: Re: [PATCH ipsec-next] net: xfrm: allow clearing socket xfrm
 policies.

On Mon, Nov 20, 2017 at 07:26:02PM +0900, Lorenzo Colitti wrote:
> Currently it is possible to add or update socket policies, but
> not clear them. Therefore, once a socket policy has been applied,
> the socket cannot be used for unencrypted traffic.
> 
> This patch allows (privileged) users to clear socket policies by
> passing in a NULL pointer and zero length argument to the
> {IP,IPV6}_{IPSEC,XFRM}_POLICY setsockopts. This results in both
> the incoming and outgoing policies being cleared.
> 
> The simple approach taken in this patch cannot clear socket
> policies in only one direction. If desired this could be added
> in the future, for example by continuing to pass in a length of
> zero (which currently is guaranteed to return EMSGSIZE) and
> making the policy be a pointer to an integer that contains one
> of the XFRM_POLICY_{IN,OUT} enum values.
> 
> An alternative would have been to interpret the length as a
> signed integer and use XFRM_POLICY_IN (i.e., 0) to clear the
> input policy and -XFRM_POLICY_OUT (i.e., -1) to clear the output
> policy.
> 
> Tested: https://android-review.googlesource.com/539816
> Signed-off-by: Lorenzo Colitti <lorenzo@...gle.com>

Applied to ipsec-next, thanks Lorenzo!