Re: Is it possible to stop sessions killing eachother when they all authorize as the same role?

From: Bryn Llewellyn <bryn(at)yugabyte(dot)com>
To: "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>
Cc: pgsql-general list <pgsql-general(at)lists(dot)postgresql(dot)org>
Subject: Re: Is it possible to stop sessions killing eachother when they all authorize as the same role?
Date: 2022-09-13 03:44:30
Message-ID: E34C9A5F-832D-444C-8798-89BA8F5B386C@yugabyte.com
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-general

> david(dot)g(dot)johnston(at)gmail(dot)com wrote:
>
>> bryn(at)yugabyte(dot)com wrote:
>>
>> revoke execute on function pg_terminate_backend(int, bigint) from public;
>
> I just did this very thing in v16 (head-ish) and it worked as expected, preventing the non-superuser role from executing the function:
>
> Session 1 - superuser
> postgres=# revoke execute on function pg_terminate_backend from public;
> REVOKE
>
> Session 2 - non-superuser (normalrole with direct login)
> postgres=> select pid, usename, query, state from pg_stat_activity;
> pid | usename | query | state
> --------+------------+----------------------------------------------------------+--------
> 466663 | | <insufficient privilege> |
> 466664 | vagrant | <insufficient privilege> |
> 470387 | normalrole | select pid, usename, query, state from pg_stat_activity; | active
> 470391 | normalrole | select pg_sleep(1000); | active
> 470412 | vagrant | <insufficient privilege> |
> 466660 | | <insufficient privilege> |
> 466659 | | <insufficient privilege> |
> 466662 | | <insufficient privilege> |
> (8 rows)
>
> postgres=> select pg_terminate_backend(470391);
> ERROR: permission denied for function pg_terminate_backend

Version 16? Thus might be the clue, then. Here's the result of "select version()" with my macOS PG :

PostgreSQL 14.5 (Homebrew) on x86_64-apple-darwin20.6.0, compiled by Apple ...

The current PG doc says "PostgreSQL 14.5 Documentation". And it does seem to be a reasonable policy for me, an ordinary end user, to arrange always to use the current non-Beta software as the doc advertises it to be. I repeated my test to be doubly sure. My non-superuser normalrole with direct login, "u1", is *still* able to invoke pg_terminate_backend() and kill other "u1" sessions—even after this (as a super-user):

revoke execute on function pg_terminate_backend from public;
revoke execute on function pg_terminate_backend from u1;

It very much looks as if what I have describe was deemed to be a bug (after that behavior had survived from at least version 11) and that it's now been fixed!

Can you (or anybody) please confirm this? And if this is confirmed, then obviously I'll shut up just wait patiently until Version 16 is supported version.

In response to

Responses

Browse pgsql-general by date

  From Date Subject
Next Message Christophe Pettus 2022-09-13 03:53:07 Re: Is it possible to stop sessions killing eachother when they all authorize as the same role?
Previous Message David G. Johnston 2022-09-13 01:38:12 Re: Is it possible to stop sessions killing eachother when they all authorize as the same role?