Re: Sample pg_hba.conf allows local users to access all databases

Hi David,

David G. Johnston schreef op 2023-08-01 19:35:
> On Tue, Aug 1, 2023 at 10:13 AM William Edwards
> <wedwards(at)cyberfusion(dot)nl> wrote:
>
>> This allows all local users connecting over TCP to access all
>> databases,
>> not only the databases that the user is a member of as one might
>> expect.
>>
>> Proof that user is able to access database that it is not a member
>> of is
>> below.
>
> Roles do not gain membership in databases.

I mixed up \du and \l output (the latter has a 'Member of' column)
because I used identical names for some roles and databases. Sorry for
the confusion.

> Roles can be granted
> permissions on databases (mainly CONNECT). And all roles, via PUBLIC,
> get connect privileges on all databases by default. So the
> pg_hba.conf entry is not causing something to happen against the
> wishes of the privileges system.
>
> https://www.postgresql.org/docs/current/ddl-priv.html
>
> And yes, this is a usability vs secure-by-default that hasn't seen
> enough complaint to take on changing the default.

Understood - records in pg_hba.conf limit access preemptively during
client authentication and do not control privileges.

For completeness' sake: from what I understand, with default privileges,
this does allow users to manipulate and read objects in any 'public'
schema pre PostgreSQL 15.x
(https://www.postgresql.org/docs/15/release-15.html E.4.2).

>
> David J.

Met vriendelijke groeten,

William Edwards