Re: CREATE ROLE IF NOT EXISTS

> On Nov 9, 2021, at 8:22 AM, Stephen Frost <sfrost(at)snowman(dot)net> wrote:
>
> In terms of least-surprise, I do tend to think that the answer is "only
> care about what is explicitly put into the command"- that is, if it
> isn't in the CREATE ROLE statement then it gets left as-is. Not sure
> how others feel about that though.

bob: CREATE ROLE charlie;
bob: GRANT charlie TO david;

super_alice: CREATE OR REPLACE ROLE charlie SUPERUSER;

I think this is the sort of thing Tom and I are worried about. "david" is now a member of a superuser role, and it is far from clear that "super_alice" intended that. Even if "bob" is not malicious, having this happen by accident is pretty bad.

If we fix the existing bug that the pg_auth_members.grantor field can end up as a dangling reference, instead making sure that it is always accurate, then perhaps this would be ok if all roles granted into "charlie" had grantor="super_alice". I'm not sure that is really good enough, but it is a lot closer to making this safe than allowing the command to succeed when role "charlie" has been granted away by someone else.

—
Mark Dilger
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