[Devel] Re: [patch 1/1][RFC] do not sys_reboot when not in init_pid_ns

Daniel Lezcano dlezcano at fr.ibm.com
Tue Nov 4 14:14:14 PST 2008


Serge E. Hallyn wrote:
> Quoting Daniel Lezcano (dlezcano at fr.ibm.com):
>> Daniel Hokka Zakrisson wrote:
>>> Daniel Lezcano wrote:
>>>
>>> Wouldn't it be better to simply remove CAP_SYS_BOOT from containers
>>> until sys_reboot emits some signal to userspace to restart/halt the
>>> container? (This is what we do in Linux-VServer.)
>> Ok, I will try, thanks.
>>
>> BTW, isn't possible that a process gave CAP_SYS_BOOT capability again to 
>>   himself and being able to shutdown the host ? I guess I should remove 
>> CAP_SETPCAP too, no ?
> 
> No, remove it from your bounding set.  You can never add bits back to
> that set.  prctl(PR_CAPBSET_DROP, CAP_SYS_BOOT);

Tested with lxc and debian minimal, I can halt/shutdown the container 
from inside. Cool !

Thanks.
  -- Daniel
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