linux-kernel - Re: [PATCH v4 0/2] Add further ioctl() operations for namespace discovery

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Message-ID: <87wpd82ear.fsf@xmission.com>
Date:   Fri, 03 Feb 2017 15:34:04 +1300
From:   ebiederm@...ssion.com (Eric W. Biederman)
To:     "Michael Kerrisk \(man-pages\)" <mtk.manpages@...il.com>
Cc:     "Serge E. Hallyn" <serge@...lyn.com>,
        Linux API <linux-api@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        "linux-fsdevel\@vger.kernel.org" <linux-fsdevel@...r.kernel.org>,
        Andrey Vagin <avagin@...nvz.org>,
        James Bottomley <James.Bottomley@...senpartnership.com>,
        "W. Trevor King" <wking@...mily.us>,
        Alexander Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH v4 0/2] Add further ioctl() operations for namespace discovery

ebiederm@...ssion.com (Eric W. Biederman) writes:

> "Michael Kerrisk (man-pages)" <mtk.manpages@...il.com> writes:
>
>
>> On 25 January 2017 at 15:28, Eric W. Biederman <ebiederm@...ssion.com> wrote:
>
>>> My concern is that the difference between returning -EOVERFLOW and
>>> overflow_uid is primarily about usability.  If you haven't played with
>>> the usability I don't trust that we have made the proper trade off.
>>
>> So, I had not initially included the no-UID-mapping case, and when you
>> proposed -EOVERFLOW for that case, it seemed better.
>>
>> On reflection, mapping to the overflow_uid seems simpler. Taking the
>> example shown in my other mail a short time ago, the unmapped UID 0
>> from the outer namespace would map to the overflow_uid (which UID my
>> program would print), but my program would still correctly report that
>> the UID 0 process in the outer namespace might (subject to LSM checks)
>> have capabilities in the inner namespace.
>>
>> So, it seems that reverting the EOVERFLOW change is in order (and my
>> example program thus needs no changes). Does that sound reasonable to
>> you?
>
> It does.  I just care that you have thought through the tradeoffs of
> that corner of the interface design.

So I have just reverted the EOVERFLOW change, applied the patches to
my tree and pushed this to for-next.  Otherwise this looks like this
effort will have stalled.

Eric