From: Tom Lane <tgl@sss.pgh.pa.us>
To: Peter Geoghegan <pg@bowt.ie>
Cc: Michael Paquier <michael@paquier.xyz>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Adrien Nayrat <adrien.nayrat@anayrat.info>
Cc: Thomas Munro <thomas.munro@enterprisedb.com>
Cc: Dmitry Dolgov <9erthalion6@gmail.com>
Cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: Vik Fearing <vik.fearing@2ndquadrant.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: David Rowley <david.rowley@2ndquadrant.com>
Cc: Pg Hackers <pgsql-hackers@postgresql.org>
Subject: Re: random() (was Re: New GUC to sample log queries)
Date: Thu, 27 Dec 2018 14:33:34 -0500
Message-ID: <9585.1545939214@sss.pgh.pa.us> (raw)
In-Reply-To: <CAH2-WznuXsWmjnvbt=odKMVxpj1zutgzRb7s6Vu3VPXCjejS5g@mail.gmail.com>
References: <20181129214850.kiq6mvofsgplqjdr@alvherre.pgsql>
<3859.1545849900@sss.pgh.pa.us>
<20181227013458.GF2106@paquier.xyz>
<32696.1545875185@sss.pgh.pa.us>
<CAH2-Wz=xJiy+BgU7M49L6EHSkMbJWbzbprge=AqyOC8aDXRj8A@mail.gmail.com>
<2820.1545878340@sss.pgh.pa.us>
<CAH2-WznuXsWmjnvbt=odKMVxpj1zutgzRb7s6Vu3VPXCjejS5g@mail.gmail.com>
Peter Geoghegan <pg@bowt.ie> writes:
> On Wed, Dec 26, 2018 at 6:39 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Now, we could probably fix that with some less intrusive patch than
>> #define'ing random() --- in particular, if we give drandom and setseed
>> their own private PRNG state, we've really fixed the security exposure
>> without need to change anything else anywhere. So maybe we should
>> just do that and be happy.
> +1. I don't like the idea of #define'ing random() myself.
> We're already making fairly broad assumptions about our having control
> of the backend's PRNG state within InitProcessGlobals(). How should
> this affect the new drandom()/setseed() private state, if at all?
I would think that InitProcessGlobals would initialize drandom's
seed alongside random()'s seed. Hopefully to values not easily
predictable from each other -- see also Munro's comment, which
I'll respond to in a moment.
regards, tom lane
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To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, pg@bowt.ie, michael@paquier.xyz, alvherre@2ndquadrant.com, adrien.nayrat@anayrat.info, thomas.munro@enterprisedb.com, 9erthalion6@gmail.com, tomas.vondra@2ndquadrant.com, vik.fearing@2ndquadrant.com, robertmhaas@gmail.com, david.rowley@2ndquadrant.com
Subject: Re: random() (was Re: New GUC to sample log queries)
In-Reply-To: <9585.1545939214@sss.pgh.pa.us>
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