| From: | Bertrand Drouvot <bertranddrouvot(dot)pg(at)gmail(dot)com> |
|---|---|
| To: | shveta malik <shveta(dot)malik(at)gmail(dot)com> |
| Cc: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, "Zhijie Hou (Fujitsu)" <houzj(dot)fnst(at)fujitsu(dot)com>, Peter Smith <smithpb2250(at)gmail(dot)com>, Ajin Cherian <itsajin(at)gmail(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Nisha Moond <nisha(dot)moond412(at)gmail(dot)com>, "Hayato Kuroda (Fujitsu)" <kuroda(dot)hayato(at)fujitsu(dot)com>, Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com>, Peter Eisentraut <peter(dot)eisentraut(at)enterprisedb(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> |
| Subject: | Re: Synchronizing slots from primary to standby |
| Date: | 2024-02-23 09:07:23 |
| Message-ID: | ZdhgS/Npe04JPZlp@ip-10-97-1-34.eu-west-3.compute.internal |
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| Lists: | pgsql-hackers |
Hi,
On Fri, Feb 23, 2024 at 02:15:11PM +0530, shveta malik wrote:
> On Fri, Feb 23, 2024 at 1:28 PM Bertrand Drouvot
> <bertranddrouvot(dot)pg(at)gmail(dot)com> wrote:
> >
> > Hi,
> >
> > Because one could create say the "=" OPERATOR in their own schema, attach a
> > function to it doing undesired stuff and change the search_path for the database
> > the sync slot worker connects to.
> >
> > Then this new "=" operator would be used (instead of the pg_catalog.= one),
> > triggering the "undesired" function as superuser.
>
> Thanks for the details. I understand it now. We do not use '=' in our
> main slots-fetch query but we do use '=' in remote-validation query.
> See validate_remote_info().
Oh, right, I missed it during the review.
> Do you think instead of doing the above,
> we can override search-path with empty string in the slot-sync case.
> SImilar to logical apply worker and autovacuum worker case (see
> InitializeLogRepWorker(), AutoVacWorkerMain()).
Yeah, we should definitively ensure that any operators being used in the query
is coming from the pg_catalog schema (could be by setting the search path or
using the up-thread proposal).
Setting the search path would prevent any risks in case the query is changed
later on, so I'd vote for changing the search path in validate_remote_info()
and in synchronize_slots() to be on the safe side.
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
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