linux-kernel - Re: [PATCH v2 1/6] xfrm/compat: Add 64=>32-bit messages translator

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Message-ID: <20200907112411.GK20687@gauss3.secunet.de>
Date:   Mon, 7 Sep 2020 13:24:11 +0200
From:   Steffen Klassert <steffen.klassert@...unet.com>
To:     Dmitry Safonov <dima@...sta.com>
CC:     <linux-kernel@...r.kernel.org>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Florian Westphal <fw@...len.de>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Jakub Kicinski <kuba@...nel.org>,
        Stephen Suryaputra <ssuryaextr@...il.com>,
        <netdev@...r.kernel.org>
Subject: Re: [PATCH v2 1/6] xfrm/compat: Add 64=>32-bit messages translator

On Wed, Aug 26, 2020 at 02:49:44AM +0100, Dmitry Safonov wrote:
> XFRM is disabled for compatible users because of the UABI difference.
> The difference is in structures paddings and in the result the size
> of netlink messages differ.
> 
> Possibility for compatible application to manage xfrm tunnels was
> disabled by: the commmit 19d7df69fdb2 ("xfrm: Refuse to insert 32 bit
> userspace socket policies on 64 bit systems") and the commit 74005991b78a
> ("xfrm: Do not parse 32bits compiled xfrm netlink msg on 64bits host").
> 
> This is my second attempt to resolve the xfrm/compat problem by adding
> the 64=>32 and 32=>64 bit translators those non-visibly to a user
> provide translation between compatible user and kernel.
> Previous attempt was to interrupt the message ABI according to a syscall
> by xfrm_user, which resulted in over-complicated code [1].
> 
> Florian Westphal provided the idea of translator and some draft patches
> in the discussion. In these patches, his idea is reused and some of his
> initial code is also present.

One comment on this. Looks like the above is the same in all
commit messages. Please provide that generic information
with the patch 0/n and remove it from the other patches.