linux-kernel - Re: RFC: sort out get

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200930161742.GF4441@mtj.duckdns.org>
Date:   Wed, 30 Sep 2020 12:17:42 -0400
From:   Tejun Heo <tj@...nel.org>
To:     Christoph Hellwig <hch@....de>
Cc:     Jens Axboe <axboe@...nel.dk>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
        Minho Ban <mhban@...sung.com>, cgroups@...r.kernel.org,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: Re: RFC: sort out get_gendisk abuses

Hello, Christoph.

On Fri, Sep 25, 2020 at 06:14:45PM +0200, Christoph Hellwig wrote:
> this series tries to remove two abuses of the get_gendisk API.
> The first one is fairly straigt forward and switched the blk-cgroup
> configuration API to properly open the block device, but I'd love to see
> it reviewed and tested by the cgroup maintainers, as I don't really know
> how this code is actually used.

I'm a bit worried that requiring fully opening the device for configuration
can lead to surprising behaviors. A now-unlikely but still possible case
would be trying to configure IO parameters for a device w/ removeable media.
All that the user is trying to do is configuring a bunch of parameters but
the kernel would try to spin up the media and fail configuration and so on.

The use case of needing to access the associated data structures without
fully activating the IO device seems valid to me. Whether that interface is
blkdev_get() or something better abstracted, I don't really care.

Thanks.

-- 
tejun