linux-kernel - Re: [RFC] block: relax permission for Persistent Reservations ioctl

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Message-ID: <319aa379-2694-5bb7-b79e-5401e894f390@linux.alibaba.com>
Date:   Sat, 10 Jun 2023 16:12:00 +0800
From:   Jingbo Xu <jefflexu@...ux.alibaba.com>
To:     Christoph Hellwig <hch@....de>
Cc:     axboe@...nel.dk, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, tianjia.zhang@...ux.alibaba.com,
        xiang@...nel.org, casey@...aufler-ca.com
Subject: Re: [RFC] block: relax permission for Persistent Reservations ioctl



On 6/10/23 2:06 PM, Christoph Hellwig wrote:
> On Fri, Jun 09, 2023 at 06:21:22PM +0800, Jingbo Xu wrote:
>> When the shared storage is accessed from containers [1], it's not
>> recommended to grant CAP_SYS_ADMIN to containers for access to
>> Persistent Reservations in risk of container escape.
>>
>> Remove the extra CAP_SYS_ADMIN permission constraint for Persistent
>> Reservations ioctl which shall do no harm [2].
> 
> I think we still to check that if CAP_SYS_ADMIN is not present,
> the file descriptors needs to be open for write, and we're not called
> on a partition (the latter should probbaly be always checked,
> as a reservation for a partitions doesn't make sense).
> 
> But in general I think relaxing this is a good idea, we just need to
> be very careful.  Looking at the discussion of unprivileged nvme
> command passthrough might be a good start.

Hi,

Thanks for the reply.

It seems I need to dive deeper into details of Persistent Reservations
protocol and the permission control you mentioned in nvme command
passthrough.

Thanks for your suggestions.  I will send a new version later.

-- 
Thanks,
Jingbo