Re: For review: user_namespace(7) man page

From: Michael Kerrisk (man-pages)
Date: Sat Sep 13 2014 - 22:42:41 EST


On 09/11/2014 08:14 AM, Andy Lutomirski wrote:
> On Thu, Sep 11, 2014 at 7:46 AM, Michael Kerrisk (man-pages)
> <mtk.manpages@xxxxxxxxx> wrote:
>> Hi Eric,
>>
>> On 09/09/2014 09:05 AM, Eric W. Biederman wrote:
>>> "Michael Kerrisk (man-pages)" <mtk.manpages@xxxxxxxxx> writes:
>>>
>>>> Hi Andy, and Eric,
>>>>>> 1. The writing process must have the CAP_SETUID (CAP_SETGID)
>>>>>> capability in the user namespace of the process pid.
>>>>>
>>>>> This checked for the opening process (and I don't actually remember
>>>>> whether it's checked for the writing process).
>>>>
>>>> Eric, can you comment?
>>>
>>> We have to check for the opening processes and that changes was made
>>> after I implemented my interface. Pieces of the code appear to also
>>> examine the writing process and verify everything applies to it as well.
>>>
>>> I goofed when I designed the interface originall and had not realized
>>> what a classic design error it can be to not restrict by the opening
>>> process.
>>
>> So, I still need some help here. Should the sentence above just read:
>>
>> 1. The *opening* process must have the CAP_SETUID (CAP_SETGID)
>> capability in the user namespace of the process pid.
>
> I think this is sufficient.
>
>>
>> or must something also be said about the writing process? (If so, i'd
>> appreciate a completely formed sentence or two that I can just drop into
>> the man page..)
>
> There might be a restriction there, too, but I think it could be
> removed, and I also think that it's unlikely that anyone will
> encounter it.

Okay. Thanks, Andy.

Cheers,

Michael


--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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