From: Paolo Bonzini <pbonzini@redhat.com>
To: Ric Wheeler <ricwheeler@gmail.com>
Cc: axboe@kernel.dk, Mike Snitzer <snitzer@redhat.com>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org
Subject: Re: [Ping^3] Re: [PATCH] sg_io: allow UNMAP and WRITE SAME without CAP_SYS_RAWIO
Date: Thu, 06 Sep 2012 08:31:33 +0200 [thread overview]
Message-ID: <50484345.8040508@redhat.com> (raw)
In-Reply-To: <5047B38D.9000607@gmail.com>
Il 05/09/2012 22:18, Ric Wheeler ha scritto:
>>
>
> Hi Paolo,
>
> Both of these commands are destructive. WRITE_SAME (if done without the
> discard bits set) can also take a very long time to be destructive and
> tie up the storage.
FORMAT_UNIT has the same characteristics and yet it is allowed (btw, I
don't think WRITE SAME slowness is limited to the case where a real
write is requested; discarding can be just as slow).
Also, the two new commands are anyway restricted to programs that have
write access to the disk. If you have read-only access, you won't be
able to issue any destructive command (there is one exception, START
STOP UNIT is allowed even with read-only capability and is somewhat
destructive).
Honestly, the only reason why these two commands weren't included, is
that the current whitelist is heavily tailored towards CD/DVD burning.
> I think that restricting them to CAP_SYS_RAWIO seems reasonable - better
> to vet and give the appropriate apps the needed capability than to
> widely open up the safety check?
CAP_SYS_RAWIO is so wide in its scope, that anything that requires it is
insecure.
Paolo
next prev parent reply other threads:[~2012-09-06 6:31 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-20 16:30 [PATCH] sg_io: allow UNMAP and WRITE SAME without CAP_SYS_RAWIO Paolo Bonzini
2012-08-01 15:53 ` Paolo Bonzini
2012-08-28 11:04 ` Paolo Bonzini
2012-09-05 14:41 ` [Ping^3] " Paolo Bonzini
2012-09-05 20:18 ` Ric Wheeler
2012-09-06 6:31 ` Paolo Bonzini [this message]
2012-09-06 11:31 ` Ric Wheeler
2012-09-06 11:49 ` Paolo Bonzini
2012-09-06 12:08 ` Ric Wheeler
2012-09-06 12:36 ` Paolo Bonzini
2012-09-06 14:20 ` Lukáš Czerner
2012-09-11 16:59 ` Tejun Heo
2012-09-11 17:56 ` Paolo Bonzini
2012-09-11 18:29 ` Tejun Heo
2012-09-11 18:54 ` Paolo Bonzini
2012-09-11 19:13 ` Tejun Heo
2012-09-11 19:24 ` Paolo Bonzini
2012-09-11 20:01 ` Tejun Heo
2012-09-11 21:50 ` Paolo Bonzini
2012-09-11 22:02 ` Tejun Heo
2012-09-11 22:10 ` Paolo Bonzini
2012-09-11 22:13 ` Tejun Heo
2012-09-12 8:05 ` James Bottomley
2012-09-12 8:18 ` Paolo Bonzini
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