Re: [gentoo-dev] Requirements for UID/GID management

[Michael Orlitzky]

On 01/28/2017 09:22 PM, Rich Freeman wrote:
>>
>> Here's a problem I have no solution for. Suppose we tell everyone to
>> pick a fixed UID for their user packages. I have a randomly assigned
>> "tcpdump" user as UID 102 on my machine today. If we roll this out next
>> week and the tcpdump maintainer chooses UID=321 as his fixed UID, what
>> happens when I go to install sys-user/tcpdump? Every option is bad:
>>
>>   * Keep the existing user. Now its UID is wrong. You might say "so
>>     what," but the majority of users on the majority of systems are
>>     going to have this problem, so you have to wonder what we've
>>     gained by deciding on fixed UIDs and then ultimately assigning
>>     them randomly anyway.
>
> Honestly, I really will say "so what" here.  :)
>
> Sure, it isn't a perfect solution, but it costs you nothing, and the
> fallback is just random UIDs, which as we've already established
> aren't a huge problem.  For new installs things will be more
> consistent.
>


"Fixed UIDs with random fallback" and "random UIDs" are the same thing.
If our goal is to make things easy on people who need fixed UIDs, then
they should be truly fixed. Even on a new machine, you might wind up
with all of the preferred UIDs, or they might all be wrong. Suppose I
add a new user 21 on my fresh install. The ftp server was going to use
21, but now it falls back to 22. The SSH daemon was going to take 22,
but now it falls back to 23. The telnet daemon was going to take 23...
That doesn't help NFS users. It's still random in the sense that it
depends on the state of the system in an unpredictable way.

And what about packages that truly require a fixed UID? I think that's
the only place my current implementation and your proposal differ. I
have it die() under the assumption that most ebuilds won't request a
UID. If everyone picks a UID and we can ignore it, what do we do about
the packages that actually need what they asked for?