Re: Extension pg_trgm, permissions and pg_dump order

[ redirecting to -bugs ]

=?iso-8859-1?Q?F=E4rber=2C_Franz-Josef_=28StMUK=29?= <Franz-Josef(dot)Faerber(at)stmuk(dot)bayern(dot)de> writes:
> My minimal example goes like this: On the fresh container, execute

> ```sql
> CREATE ROLE limitedrole;
> CREATE SCHEMA ext_trgm;
> CREATE EXTENSION pg_trgm SCHEMA ext_trgm;
> GRANT USAGE ON SCHEMA ext_trgm TO limitedrole;

> SET ROLE limitedrole;
> CREATE TABLE x(y text);
> CREATE INDEX ON x USING gist(y ext_trgm.gist_trgm_ops);
> ```

> Dump the database with `pg_dump > /tmp/x`, then do
> ```sql
> DROP SCHEMA ext_trgm CASCADE; DROP TABLE x;
> ```
> (or alternatively create a fresh database and do a ` CREATE ROLE limitedrole;`)

> Then try to restore the dump with `cat /tmp/x | psql`.

> On version 14.2, this succeeds.
> On version 14.3, this fails with "ERROR: permission denied for schema ext_trgm".

I think what is happening here is that parse analysis of the index
expression is now being done as the owner of the table (already assigned
as limitedrole), as a consequence of the patch for CVE-2022-1552.

So basically, that patch has completely broken pg_dump's scheme for
when it can issue GRANTs. I'm not sure there is a simple fix :-(.
We could issue the GRANTs earlier but that is going to break some
other use-cases, if memory serves.

regards, tom lane