From: Nathan Bossart <nathandbossart@gmail.com>
To: Noah Misch <noah@leadboat.com>
Cc: Michael Paquier <michael@paquier.xyz>
Cc: pgsql-bugs@lists.postgresql.org, Färber, Franz-Josef (StMUK) <Franz-Josef.Faerber@stmuk.bayern.de>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Subject: Re: Extension pg_trgm, permissions and pg_dump order
Date: Wed, 22 Jun 2022 09:25:50 -0700
Message-ID: <20220622162550.GA95419@nathanxps13> (raw)
In-Reply-To: <20220622033704.GA4167527@rfd.leadboat.com>
References: <20220529043403.GB3265235@rfd.leadboat.com>
<YpWZ02YEN9pipA6M@paquier.xyz>
<20220531152855.GA2236210@nathanxps13>
<20220603181724.GA2672350@nathanxps13>
<20220606063056.GA3527347@rfd.leadboat.com>
<20220609051708.GA3615673@rfd.leadboat.com>
<20220613034551.GB3728437@rfd.leadboat.com>
<20220616054218.GA3980475@rfd.leadboat.com>
<20220621175616.GA93985@nathanxps13>
<20220622033704.GA4167527@rfd.leadboat.com>
On Tue, Jun 21, 2022 at 08:37:04PM -0700, Noah Misch wrote:
> On Tue, Jun 21, 2022 at 10:56:16AM -0700, Nathan Bossart wrote:
>> On Wed, Jun 15, 2022 at 10:42:18PM -0700, Noah Misch wrote:
>> > + * Identify the opclass to use. Use of ddl_userid is necessary due to
>> > + * ACL checks therein. This is safe despite opclasses containing
>> > + * opaque expressions (specifically, functions), because only
>> > + * superusers can define opclasses.
>>
>> It's not clear to me why the fact that only superusers can define opclasses
>> makes this safe.
>
> classOidP[attn] = ResolveOpClass(attribute->opclass,
> atttype,
> accessMethodName,
> accessMethodId);
>
> To write the comment, I pondered how those four arguments could conceivably
> lead ResolveOpClass() to locate Trojan code. Since only superusers can define
> opclasses, we can assume the catalog entries of an opclass do not point to
> Trojan code. (The superuser could just do the mischief directly, rather than
> going to extra trouble to set a trap for later.) If you see a hole in that
> thinking, please do share.
Thanks for clarifying. That makes sense to me.
--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com
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To: pgsql-bugs@postgresql.org
Cc: nathandbossart@gmail.com, noah@leadboat.com, michael@paquier.xyz, Franz-Josef.Faerber@stmuk.bayern.de, tgl@sss.pgh.pa.us
Subject: Re: Extension pg_trgm, permissions and pg_dump order
In-Reply-To: <20220622162550.GA95419@nathanxps13>
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