Re: [HACKERS] QGIS Seem To Bypass PostgreSQL/PostGIS User Privileges/Permissions - Mailing list pgsql-hackers

While I do not know QGIS, I'm wondering if it's similar to some of our applications where they always use the same system login for the database while each user provides a unique login to the application. Have you ever set log_connections in your postgresql.conf file? That would show you which user is connecting during your attempts, and they might very well be something you're not expecting. As far as I know, there is no way for any application to bypass PostgreSQL's internal security model.

On Fri, Mar 17, 2017 at 11:43 AM, Osahon Oduware <oduwareosahon@gmail.com> wrote:

Hi Giuseppe,

Thanks for the response. I have provided the GRANTS and other PostgreSQL setup scripts below as it includes what you have suggested:

ROLE

---------

CREATE ROLE <role_name> WITH NOLOGIN NOSUPERUSER INHERIT NOCREATEDB NOCREATEROLE NOREPLICATION;

USER

----------

CREATE USER <username> WITH PASSWORD '<password>'

REVOKES

----------------

REVOKE ALL PRIVILEGES ON DATABASE <database_name> FROM PUBLIC;

REVOKE ALL PRIVILEGES ON DATABASE postgres FROM PUBLIC;

GRANTS

-------------

GRANT CONNECT ON DATABASE <database_name> TO <role_name>;

GRANT USAGE ON SCHEMA <schema_name> TO <role_name>;

GRANT SELECT ON ALL TABLES IN SCHEMA <schema_name> TO <role_name>;

GRANT <role_name> TO <username>;

I cannot but wonder why these privileges are working when tested in pgAdmin/pgsql, but not in QGIS with the same user/schema/table/database.

On Fri, Mar 17, 2017 at 4:16 PM, Giuseppe Broccolo <giuseppe.broccolo@2ndquadrant.it> wrote:

Hi Osahon,

2017-03-17 15:54 GMT+01:00 Osahon Oduware <oduwareosahon@gmail.com>:

Hi All,

I created a "Read-only" User in PostgreSQL via a Role with "SELECT" ONLY privilege on all tables in a schema as shown below:

GRANT SELECT ON ALL TABLES IN SCHEMA [schema_name] TO [role_name]

GRANT [role_name] TO [user_name]

I'd have done this as followed:

REVOKE ALL ON SCHEMA [schema_name] FROM PUBLIC;
GRANT USAGE ON SCHEMA [schema_name] TO [role_name];
GRANT SELECT ON ALL TABLES IN SCHEMA [schema_name] TO [role_name];

GRANT [role_name] TO [user_name];

 

Next, I test this by trying to UPDATE a column in a table (same schema as above) with pgAdmin/psql and this works fine by giving a response that the user has no permission - 'ERROR: permission denied for relation <table_name>.'

Next, I connect with the same user in QGIS and add a layer from the same table (same schema as above). I open the attribute table for the layer, turn on editing mode (by clicking on the pencil-like icon), and edit the same field/column above. To my surprise, the edit was saved successfully without any permission error prompt.

Next, I check the value of the field/column (same table/schema as above) in pgAdmin/psql and it is having the new (edited) value from QGIS. This is rather strange as it seems QGIS is bypassing the permissions set for the same user in the PostgreSQL/PostGIS database.

I will be glad if someone can help me unravel this mystery.

Check which user is used the first time you connect to the database through QGIS, and if you switch the user to [user_name] in a second moment. I'm wondering if you are keeping some privileges from a previous session.

All the best,

Giuseppe.

--

Giuseppe Broccolo - 2ndQuadrant Italy
PostgreSQL & PostGIS Training, Services and Support
giuseppe.broccolo@2ndQuadrant.it | www.2ndQuadrant.it