Обсуждение: How was I able to drop a role even though objects depend on it?

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How was I able to drop a role even though objects depend on it?

От
"Wojciechowski, Robert (GE Transportation)"
Дата:
I’ve noticed a weird situation on one of our development servers running PostgreSQL 9.1.3 where roles have been dropped
eventhough objects depend on that user. I didn’t think that was possible due to the dependency checks on DROP
USER/ROLE.For example, there is a database that shows this connect grant to a user that was known as foo1_userA (oid
3562339547):3562339547=c/postgres This happened after a nightly database import script was run that takes in new clone
databasesfrom production. After the script imports new databases another script runs that drop all users matching a
regex(/^foo1_user/ for example) to clear out stale users. This obviously should succeed dropping a user that does not
havedependent objects and should fail on users that do. For some this is not holding true. Is this a bug? Am I relying
toomuch on DROP USER/ROLE? Any alternative approaches to clearing out users that do not have dependent objects or
guidanceon debugging this situation would be much appreciated! -- Robert 


Re: How was I able to drop a role even though objects depend on it?

От
Alvaro Herrera
Дата:
Wojciechowski, Robert (GE Transportation) wrote:
> I’ve noticed a weird situation on one of our development servers running PostgreSQL 9.1.3 where roles have been
droppedeven though objects depend on that user. I didn’t think that was possible due to the dependency checks on DROP
USER/ROLE.For example, there is a database that shows this connect grant to a user that was known as foo1_userA (oid
3562339547):3562339547=c/postgres This happened after a nightly database import script was run that takes in new clone
databasesfrom production. After the script imports new databases another script runs that drop all users matching a
regex(/^foo1_user/ for example) to clear out stale users. This obviously should succeed dropping a user that does not
havedependent objects and should fail on users that do. For some this is not holding true. Is this a bug? Am I relying
toomuch on DROP USER/ROLE? Any alternative approaches to clearing out users that do not have dependent objects or
guidanceon debugging this situation would be much appreciated! -- Robert 

It sounds like a bug to me.  Can you provide a self-contained reproducer
of this?  It'd be useful to know what kind of objects (should have)
depended on that user, for instance.

--
Álvaro Herrera                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services


Re: How was I able to drop a role even though objects depend on it?

От
David Johnston
Дата:
Wojciechowski, Robert (GE Transportation) wrote
> [...] there is a database that shows this connect grant to a user that was
> known as foo1_userA (oid 3562339547): 3562339547=c/postgres

The main user dependent situation is having said user OWNER on a database
object.  Simply giving a user connect privileges on a database does not make
the database dependent upon said user and so removing said user remains
possible.

Either (or both) a more explicit description or a self-contained test case
is needed to figure out if you are simply mis-understanding the situation or
if there truly is a bug.  The sentence I quoted above leads me to think
operator-error.

David J.




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Re: How was I able to drop a role even though objects depend on it?

От
Alvaro Herrera
Дата:
David Johnston wrote:
> Wojciechowski, Robert (GE Transportation) wrote
> > [...] there is a database that shows this connect grant to a user that was
> > known as foo1_userA (oid 3562339547): 3562339547=c/postgres
>
> The main user dependent situation is having said user OWNER on a database
> object.  Simply giving a user connect privileges on a database does not make
> the database dependent upon said user and so removing said user remains
> possible.

Dropping a user which is either a database owner or has been granted
CONNECT privileges is supposed to be disallowed:

alvherre=# create user f;
CREATE ROLE
alvherre=# create database f owner f;
CREATE DATABASE
alvherre=# drop role f;
ERROR:  role "f" cannot be dropped because some objects depend on it
DETALLE:  owner of database f
alvherre=# create role g;
CREATE ROLE
alvherre=# grant connect on database f to g;
GRANT
alvherre=# drop role g;
ERROR:  role "g" cannot be dropped because some objects depend on it
DETALLE:  privileges for database f

We're supposed to have sufficient locking so that concurrent
transactions don't see problems either (one xact drops the user while
the other creates the database), but maybe there are bugs somewhere.

--
Álvaro Herrera                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services


Re: How was I able to drop a role even though objects depend on it?

От
David Johnston
Дата:
Alvaro Herrera-9 wrote
> David Johnston wrote:
>> Wojciechowski, Robert (GE Transportation) wrote
>> > [...] there is a database that shows this connect grant to a user that
>> was
>> > known as foo1_userA (oid 3562339547): 3562339547=c/postgres
>>
>> The main user dependent situation is having said user OWNER on a database
>> object.  Simply giving a user connect privileges on a database does not
>> make
>> the database dependent upon said user and so removing said user remains
>> possible.
>
> Dropping a user which is either a database owner or has been granted
> CONNECT privileges is supposed to be disallowed:
>
> alvherre=# create user f;
> CREATE ROLE
> alvherre=# create database f owner f;
> CREATE DATABASE
> alvherre=# drop role f;
> ERROR:  role "f" cannot be dropped because some objects depend on it
> DETALLE:  owner of database f
> alvherre=# create role g;
> CREATE ROLE
> alvherre=# grant connect on database f to g;
> GRANT
> alvherre=# drop role g;
> ERROR:  role "g" cannot be dropped because some objects depend on it
> DETALLE:  privileges for database f
>
> We're supposed to have sufficient locking so that concurrent
> transactions don't see problems either (one xact drops the user while
> the other creates the database), but maybe there are bugs somewhere.

OK.  Looking at the documentation for this I see where this is stated though
I read it that only direct permissions are evaluated.  If foo1_userA is
getting permission to connect to database "postgres" via a parent role then
foo1_userA can be dropped since it would not need/have direct connect
privileges but would still how up as being allowed by the system.  I don't
know whether 3562339547 = c/postgres would show up only in the direct case
or if also via inheritance - and I'm not totally sure where this is actually
being queried in the first place.


David J.






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