linux-kernel - Re: cgroup: denying device doesn't work with 'rw' mode string

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Message-ID: <CAFeW=patEo56jXmyO6EPkDOf4oBwk1kaNE8OQASZHK-3d3zhZA@mail.gmail.com>
Date:	Fri, 18 May 2012 12:31:06 +0800
From:	Amos Kong <kongjianjun@...il.com>
To:	Li Zefan <lizefan@...wei.com>
Cc:	serue@...ibm.com, viro@...iv.linux.org.uk,
	linux-kernel@...r.kernel.org, tj@...nel.org, jmorris@...ei.org
Subject: Re: cgroup: denying device doesn't work with 'rw' mode string

On Fri, May 18, 2012 at 11:52 AM, Li Zefan <lizefan@...wei.com> wrote:
> Amos Kong wrote:
>
>> CC: Li Zefan <lizf@...fujitsu.com>, Tejun Heo <tj@...nel.org>, jmorris@...ei.org
>>
>> On Sat, Oct 15, 2011 at 8:39 AM, Amos Kong <kongjianjun@...il.com> wrote:
>>> # mount -t cgroup -o devices none /cgroup
>>> # mkdir /cgroups/devices
>>> # ls -l /dev/vg/lv
>>> lrwxrwxrwx. 1 root root 7 Oct 14 19:03 /dev/vg/lv -> ../dm-3
>>> # ls -l /dev/dm-3
>>> brw-rw----. 1 root disk 253, 3 Oct 14 19:03 /dev/dm-3


>>> ------- test1
>>> deny read-write permission of dm-3, but it doesn't effect.
>>>
>>> # echo a > devices/devices.allow
>>> # echo 'b 253:2 rw' > devices.deny
>
>
> 253:2 ??

sorry, typo

# echo 'b 253:3 rw' > devices.deny      # But read-write permission is
not denied

>>>                ^^
>>> # echo $$ > task
>>> # dd if=/dev/zero of=/dev/dm-3 bs=1M count=1
>>> can write to /dev/dm-3 successfully  (problem exists)
>>>
>>> ------- test2
>>> # echo a > devices/devices.allow
>>> # echo 'b 253:3 rwm' > devices/devices.deny
>
>
> 253:3 !!
>
>>>                ^^^
>>> # echo $$ > task
>>> # dd if=/dev/zero of=/dev/dm-3 bs=1M count=1
>>> couldn't write to /dev/dm-3 successfully
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