Thread: 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. vex=> select version(); version ------------------------------------------------------------------------- PostgreSQL 6.3.2 on i386-unknown-netbsd1.3B, compiled by gcc 2.7.2.2+myc1 (1 row) vex=> SELECT relname, relacl FROM pg_class, pg_user vex-> WHERE ( relkind = 'r' OR relkind = 'i' OR relkind = 'S') AND vex-> relname = 'client' AND vex-> usesysid = relowner vex-> ORDER BY relname; relname|relacl -------+-------------- client |{"=","root=r"} (1 row) vex=> select user; getpgusername ------------- carol (1 row) vex=> select * from client; ERROR: client: Permission denied. Exactly what I expected. Now, here is another. trends=> select version(); version -------------------------------------------------------------------------- PostgreSQL 6.4.0 on i386-unknown-netbsd1.3.2, compiled by gcc 2.7.2.2+myc1 (1 row) trends=> SELECT relname, relacl FROM pg_class, pg_user trends-> WHERE ( relkind = 'r' OR relkind = 'i' OR relkind = 'S') AND trends-> relname = 'client' AND trends-> usesysid = relowner trends-> ORDER BY relname; relname|relacl -------+--------------- client |{"=","db=arwR"} (1 row) trends=> select user; getpgusername ------------- darcy (1 row) trends=> select * from client; [Rows returned as if I had permissions] Am I missing something or did table permission protections get lost on the way to 6.4? -- D'Arcy J.M. Cain <darcy@{druid|vex}.net> | Democracy is three wolves http://www.druid.net/darcy/ | and a sheep voting on +1 416 424 2871 (DoD#0082) (eNTP) | what's for dinner.
> > 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 -- #======================================================================# # It's easier to get forgiveness for being wrong than for being right. # # Let's break this rule - forgive me. # #======================================== jwieck@debis.com (Jan Wieck) #
Thus spake Jan Wieck > I assume user carol does not have usesuper set in pg_shadow. Correct. > 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. Correct again. I half suspected something like this. Perhaps the prompt in createuser should be changed to reflect that the user is being granted full superuser privileges rather than just being able to create more users. -- D'Arcy J.M. Cain <darcy@{druid|vex}.net> | Democracy is three wolves http://www.druid.net/darcy/ | and a sheep voting on +1 416 424 2871 (DoD#0082) (eNTP) | what's for dinner.