Re: [PATCH 2/2] user_namespaces.7: Update the documention to reflect the fixes for negative groups

From: Michael Kerrisk (man-pages)
Date: Thu Feb 12 2015 - 05:11:20 EST

On 02/11/2015 03:01 PM, Eric W. Biederman wrote:
> "Michael Kerrisk (man-pages)" <mtk.manpages@xxxxxxxxx> writes:
>> Hi Eric,
>> Ping!
>> Cheers,
>> Michael
>> On 2 February 2015 at 16:37, Michael Kerrisk (man-pages)
>> <mtk.manpages@xxxxxxxxx> wrote:
>>> Hi Eric,
>>> Thanks for writing this up!
>>> On 12/12/2014 10:54 PM, Eric W. Biederman wrote:
>>>> Files with access permissions such as ---rwx---rwx give fewer
>>>> permissions to their group then they do to everyone else. Which means
>>>> dropping groups with setgroups(0, NULL) actually grants a process
>>>> privileges.
>>>> The uprivileged setting of gid_map turned out not to be safe after
> ^^^^^^^^^^^
> unprivileged -- typo fix

Thanks for confirming.

>>>> this change. Privilege setting of gid_map can be interpreted as
>>>> meaning yes it is ok to drop groups.
>>> I had trouble to parse that sentence (and I'd like to make sure that
>>> the right sentence ends up in the commit message). Did you mean:
>>> "*Unprivileged* setting of gid_map can be interpreted as meaning
>>> yes it is ok to drop groups"
>>> ?
>>> Or something else?
> I meant: Setting of gid_map with privilege has been clarified to mean
> that dropping groups is ok. This allows existing programs that set
> gid_map with privilege to work without changes. That is newgidmap
> continues to work unchanged.

Thanks. I added that text to the changelog message.



Michael Kerrisk
Linux man-pages maintainer;
Linux/UNIX System Programming Training:
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