Re: How to stop script executions

On Tue, Jul 26, 2016 at 9:05 AM, Melvin Davidson <melvin6925(at)gmail(dot)com>
wrote:

>
>
> On Tue, Jul 26, 2016 at 9:52 AM, Dev Kumkar <devdas(dot)kumkar(at)gmail(dot)com>
> wrote:
>
>> On Tue, Jul 26, 2016 at 6:59 PM, David G. Johnston <
>> david(dot)g(dot)johnston(at)gmail(dot)com> wrote:
>>
>>> ​Typically this means that given user only having psql, or some other
>>> backend protocol only, connect to the database are they able to execute
>>> arbitrary commands as the user running the PostgreSQL process on the host
>>> system.​
>>>
>>> Untrusted langauges are untrusted for specifically this reason. Without
>>> untrusted languages it requires privilege escalation to interact
>>> dynamically with the host operating system.
>>>
>>> Assuming raised privileges it is presently impossible to prevent such
>>> dynamic interaction.
>>>
>>
>> Just thinking if untrusted language like plperlu is not installed then
>> executing arbitrary commands is not possible.
>> So the other possible which you did mention was COPY FROM PROGRAM
>> command, is this understanding correct?
>>
>> Regards...
>>
>
> >COPY FROM PROGRAM
>
> I think at this point it would be most beneficial if
> 1. You stated your version of PostgreSQL & O/S
> 2. Gave a comprehensive explanation of exactly what you are trying to do.
> IOW, What exactly are you trying to prevent users from doing and why?
>

​I agree. From my reading at:
https://www.postgresql.org/docs/9.5/static/sql-copy.html the COPY FROM
PROGRAM is only available to a PostgreSQL user who is database superuser.
That, sort of, implies to me that said user is trusted not to do "evil",
but abide by the restrictions place upon him/her/it. In some strange
reality where this is not the case, and I was running on Linux, I would use
SeLinux in enforcing mode to really restrict what the id under which the
server is running could do. That is, a "don't allow unless explicitly
allowed" type policy. Or I'd "sandbox" the PostgreSQL server code using
something like docker, or under in a virtual machine with little access to
other services.

>
>
> --
> *Melvin Davidson*
> I reserve the right to fantasize. Whether or not you
> wish to share my fantasy is entirely up to you.
>

--
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Maranatha! <><
John McKown