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From: Tom Lane <[email protected]>
To: Andreas Joseph Krogh <[email protected]>
Cc: [email protected]
Subject: Re: prevent users from SELECT-ing from pg_roles/pg_database
Date: Fri, 24 May 2024 13:02:13 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <VisenaEmail.66.54f51e587b38c9cc.18fab4b4eb6@origo-test01.app.internal.visena.net>
References: <VisenaEmail.66.54f51e587b38c9cc.18fab4b4eb6@origo-test01.app.internal.visena.net>

Andreas Joseph Krogh <[email protected]> writes:
> Hi, is there a way to prevent a user/role from SELECT-ing from certain 
> system-tables?
> I'd like the contents of pg_{user,roles,database} to not be visible to all 
> users.

As noted, you can in principle revoke the public SELECT grant from
those views/catalogs.  However, the system is not designed to hide
such information, which means you'll have (at least) two kinds of
issues to worry about:

1. Queries or tools breaking that you didn't expect to break.
It's hardly uncommon for instance for queries on pg_class to
join to pg_roles to get the owner names for tables.

2. Information leaks.  For example, mapping role OID to role name
is trivial with either regrole or pg_get_userbyid(), so it
wouldn't take long to scan the plausible range of role OIDs and
get all their names, even without SQL access to the underlying
catalog.

			regards, tom lane

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