Re: Directory/File Access Permissions for COPY and Generic File Access Functions

From: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Andres Freund <andres(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Stephen Frost <sfrost(at)snowman(dot)net>, Adam Brightwell <adam(dot)brightwell(at)crunchydatasolutions(dot)com>, Peter Eisentraut <peter_e(at)gmx(dot)net>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Directory/File Access Permissions for COPY and Generic File Access Functions
Date: 2014-10-29 15:26:18
Message-ID: 20141029152618.GG1791@alvin.alvh.no-ip.org
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Robert Haas wrote:
> On Wed, Oct 29, 2014 at 10:52 AM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
> >> The larger point though is that this is just one of innumerable attack
> >> routes for anyone with the ability to make the server do filesystem reads
> >> or writes of his choosing. If you think that's something you can safely
> >> give to people you don't trust enough to make them superusers, you are
> >> wrong, and I don't particularly want to spend the next ten years trying
> >> to wrap band-aids around your misjudgment.
> >
> > ... but that doesn't necessarily address this point.
>
> I think the question is "just how innumerable are those attack
> routes"? So, we can prevent a symlink from being used via O_NOFOLLOW.
> But what about hard links?

Users cannot create a hard link to a file they can't already access.

--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

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