linux-kernel - Re: RFC: capabilities(7): notes for kernel developers

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Message-ID: <e8a6d266-9870-2591-576b-927208683b5d@gmail.com>
Date:   Fri, 16 Dec 2016 15:55:35 +0100
From:   "Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>
To:     Casey Schaufler <casey@...aufler-ca.com>,
        John Stultz <john.stultz@...aro.org>
Cc:     mtk.manpages@...il.com, "Serge E. Hallyn" <serge@...lyn.com>,
        James Morris <jmorris@...ei.org>,
        Kees Cook <keescook@...omium.org>,
        Andy Lutomirski <luto@...capital.net>,
        Jann Horn <jann@...jh.net>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        linux-man <linux-man@...r.kernel.org>,
        linux-security-module <linux-security-module@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: RFC: capabilities(7): notes for kernel developers

On 12/16/2016 01:44 AM, Casey Schaufler wrote:
> On 12/15/2016 4:31 PM, John Stultz wrote:
>> On Thu, Dec 15, 2016 at 12:40 PM, Casey Schaufler
>> <casey@...aufler-ca.com> wrote:
>>> On 12/15/2016 11:41 AM, Michael Kerrisk (man-pages) wrote:
>>>> On 12/15/2016 05:29 PM, Casey Schaufler wrote:
>>>>> CAP_WAKE_ALARM could readily be CAP_TIME.
>>>> Actually, I don't quite understand what you mean with that sentence.
>>>> Could you elaborate?
>>> Should have said CAP_SYS_TIME
>>>
>>> Setting an alarm could be considered a time management function,
>>> depending on what it actually does.
>> Just a nit here. CAP_WAKE_ALARM is more about the privilege of waking
>> a system from suspend, while CAP_SYS_TIME covers the ability to set
>> the time. One wouldn't necessarily want to give applications which
>> could wake a system up the capability to also set the time.
> 
> Doesn't really matter, except that an ignorant developer
> might make the mistake I did and assume that WAKE_ALARM
> was somehow related to time management. If you want to use
> it as an example don't let my dunderheadedness get in your
> way.

Actually, I decided it wasn't such a good example anyway.
That capability could potentially be generic. (But it probably
should better have been named something like 'CAP_WAKE_SYSTEM'.)

>> thanks
>> -john
> 
> Again, thank you for taking this on. It should be a
> big help.

You're welcome. And thanks for your help, Casey.

Cheers,

Michael


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