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

From: Li Zefan
Date: Thu May 17 2012 - 23:56:47 EST


Amos Kong wrote:

> CC: Li Zefan <lizf@xxxxxxxxxxxxxx>, Tejun Heo <tj@xxxxxxxxxx>, jmorris@xxxxxxxxx
>
> On Sat, Oct 15, 2011 at 8:39 AM, Amos Kong <kongjianjun@xxxxxxxxx> 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 ??

>> ^^
>> # 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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