Re: psql: Add role's membership options to the \du+ command - Mailing list pgsql-hackers
| From | David G. Johnston |
|---|---|
| Subject | Re: psql: Add role's membership options to the \du+ command |
| Date | |
| Msg-id | CAKFQuwY9DtC8B-eCpHe39yK+y9LardAyaEz0ccVa_pQ+xBgr2Q@mail.gmail.com Whole thread Raw |
| In response to | Re: psql: Add role's membership options to the \du+ command (Pavel Luzanov <p.luzanov@postgrespro.ru>) |
| Responses |
Re: psql: Add role's membership options to the \du+ command
|
| List | pgsql-hackers |
On Fri, Mar 3, 2023 at 4:01 AM Pavel Luzanov <p.luzanov@postgrespro.ru> wrote:
Hello,On 22.02.2023 00:34, David G. Johnston wrote:I didn't even know this function existed. But I see that it was changed in 3d14e171 with updated documentation:I think that should probably have ADMIN as one of the options as well. Also curious what it reports for an empty membership.
I've been experimenting for a few days and I want to admit that this is a very difficult and not obvious topic.
I'll try to summarize what I think.
1.
About ADMIN value for pg_has_role.
Implementation of ADMIN value will be different from USAGE and SET.
To be True, USAGE value requires the full chain of memberships to have INHERIT option.
Similar with SET: the full chain of memberships must have SET option.
But for ADMIN, only last member in the chain must have ADMIN option and all previous members
must have INHERIT (to administer directly) or SET option (to switch to role, last in the chain).
Therefore, it is not obvious to me that the function needs the ADMIN value.
Or you can SET to some role that then has an unbroken INHERIT chain to the administered role.
ADMIN basically implies SET/USAGE but it doesn't work the other way around.
I'd be fine with "pg_can_admin_role" being a newly created function that provides this true/false answer but it seems indisputable that today there is no core-provided means to answer the question "can one role get ADMIN rights on another role". Modifying \du to show this seems out-of-scope but the pg_has_role function already provides that question for INHERIT and SET so it is at least plausible to extend it to include ADMIN, even if the phrase "has role" seems a bit of a misnomer. I do cover this aspect with the Role Graph pseudo-extension but given the presence and ease-of-use of a boolean-returning function this seems like a natural addition. We've also survived quite long without it - this isn't a new concept in v16, just a bit refined.
2.
pg_has_role function description starts with: Does user have privilege for role?
- This is not exact: function works not only with users, but with NOLOGIN roles too.
- Term "privilege": this term used for ACL columns, such usage may be confusing,
especially after adding INHERIT and SET in addition to ADMIN option.
Yes, it missed the whole "there are only roles now" memo. I don't have an issue with using privilege here though - you have to use the GRANT command which "defines access privileges". Otherwise "membership option" or maybe just "option" would need to be explored.
3.
It is possible to grant membership with all three options turned off:
grant a to b with admin false, inherit false, set false;
But such membership is completely useless (if i didn't miss something).
May be such grants must be prohibited. At least this may be documented in the GRANT command.
I have no issue with prohibiting the "empty membership" if someone wants to code that up.
4.
Since v16 it is possible to grant membership from one role to another several times with different grantors.
And only grantor can revoke membership.
- This is not documented anywhere.
Yeah, a pass over the GRANTED BY actual operation versus documentation seems warranted.
- Current behavior of \du command with duplicated roles in "Member of" column strongly confusing.
This is one of the goals of the discussion patch.
This indeed needs to be fixed, one way (include grantor) or the other (du-duplicate), with the current proposal of including grantor getting my vote.
I think to write about this to pgsql-docs additionally to this topic.
I wouldn't bother starting yet another thread in this area right now, this one can absorb some related changes as well as the subject line item.
David J.
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