Re: [HACKERS] Permissions not working?

>
> Something seems to be wrong here unless I am doing something wrong that
> I can't see. Here is a dump of one session.
>
> version
> -------------------------------------------------------------------------
> PostgreSQL 6.3.2 on i386-unknown-netbsd1.3B, compiled by gcc 2.7.2.2+myc1
>
> relname|relacl
> -------+--------------
> client |{"=","root=r"}
>
> getpgusername
> -------------
> carol
>
> vex=> select * from client;
> ERROR: client: Permission denied.
>
> Exactly what I expected. Now, here is another.

I assume user carol does not have usesuper set in pg_shadow.

> version
> --------------------------------------------------------------------------
> PostgreSQL 6.4.0 on i386-unknown-netbsd1.3.2, compiled by gcc 2.7.2.2+myc1
>
> relname|relacl
> -------+---------------
> client |{"=","db=arwR"}
>
> getpgusername
> -------------
> darcy
>
> trends=> select * from client;
> [Rows returned as if I had permissions]

Here I assume user darcy has usesuper set in pg_shadow. Check
and correct me if I'm wrong. The superuser flag is set if you
allow darcy to create users on createuser time.

> Am I missing something or did table permission protections get lost on
> the way to 6.4?

The only thing changed is that relations accessed due to
rewrite rules get checked against the owner of the relation,
the rules are fired for (ev_class attribute of pg_rewrite).
This was only done for read access due to rules in 6.3 and
now does also check for append/write access since we open all
rules to regular users in 6.4.

Someone can now setup a view from tables she has access to
and then grant access to the view but does not need to grant
access to the tables the view is made of. This is how we make
pg_user (a view) publicly readable but protect pg_shadow (the
selected table) from public access.

Or someone can setup rules on insert, update and delete to
one table (granted) that do logging of these events into a
log table (not granted).

All the required permissions are checked during the actual
query rewriting. Thus, later ACL changes will correctly be
in effect. Example:

Table t1 owner user_a granted select to user_b
View v1 owner user_b granted select to user_c

user_c can select from v1

Now user_a revokes select on t1 from user_b

user_c gets 't1: permission denied' on select from v1

But if user_b is a superuser (usesuper set)

user_c can still select from v1

Jan

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