Date: Thu, 7 Jul 2022 11:40:01 -0700
From: Nathan Bossart <nathandbossart@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Michael Paquier <michael@paquier.xyz>, pgsql-hackers@postgresql.org
Subject: Re: pg_parameter_aclcheck() and trusted extensions
Message-ID: <20220707184001.GA2255643@nathanxps13>
References: <20220706224727.GA2158260@nathanxps13>
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On Thu, Jul 07, 2022 at 12:41:00PM -0400, Tom Lane wrote:
> Yeah.  So the fix here seems pretty obvious: rather than applying the
> permissions check using bare GetUserId(), we need to remember the role
> OID that originally applied the setting, and use that.

Please ignore my previous message.  This makes sense.

> The problem with this sketch is that
> 
> (1) we need an OID field in struct config_generic, as well as GucStack,
> which means an ABI break for any extensions that look directly at GUC
> records.  There probably aren't many, but ...
> 
> (2) we need an additional parameter to set_config_option, which
> again is a compatibility break for anything calling that directly.
> There surely are such callers --- our own extensions do it.
> 
> Can we get away with doing these things in beta3?  We could avoid
> breaking (2) in the v15 branch by making set_config_option into
> a wrapper around set_config_option_ext, or something like that;
> but the problem with struct config_generic seems inescapable.
> (Putting the new field at the end would solve nothing, since
> config_generic is embedded into larger structs.)
> 
> The alternative to API/ABI breaks seems to be to revert the
> feature, which would be sad.

I personally lean more towards the compatibility break than reverting the
feature.  There are still a couple of months before 15.0, and I suspect it
won't be too difficult to fix any extensions that break because of this.

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com