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From: "Érico Nogueira" <>
To: <>
Cc: <>
Subject: Re: [musl] $ORIGIN rpath expansion without /proc: code looks wrong
Date: Thu, 18 Nov 2021 16:21:13 -0300	[thread overview]
Message-ID: <CFT5E45O9EIZ.B4QEQ40XC711@mussels> (raw)
In-Reply-To: <>

On Wed Nov 17, 2021 at 5:01 PM -03, Jeffrey Walton wrote:
> On Wed, Nov 17, 2021 at 12:09 PM Érico Nogueira <>
> wrote:
> >
> > On Wed Nov 17, 2021 at 11:04 AM -03, Alexander Sosedkin wrote:
> > > ...
> > > Could somebody take a look at this and double-check that
> > > this codepath makes sense?
> >
> > It does, but it might not be as robust as you wish. fixup_rpath() treats
> > the RPATH entry as a single string, and does all $ORIGIN substitutions
> > in one go (what splits the string by ":" is open_path()). This means
> > that the entire RPATH entry containing $ORIGIN will be ignored if
> > /proc/self/exe can't be accessed, despite one or more of them not
> > depending on $ORIGIN.
> This has come up before on the list. It is different behavior from
> libc, and it may be CVE worthy if a down-level library is used when an
> updated library is available but lost because the RPATH/RUNPATH is
> discarded.

I would file such a CVE on the distro packaging or system administration
rather than musl. The binaries you need to run so /proc is mounted
shouldn't be the sort that depend on dynamic RPATH using ${ORIGIN}
(rather than a static one or no RPATH at all), and any security fix
should be confirmed to actually work before being deployed...

Furthermore, I don't think an unprivileged user should be able to
unmount /proc unless they have called prctl(PR_SET_NO_NEW_PRIVS, 1), no?
Which would make any "attacks" be directed at themselves.

> Jeff

  reply	other threads:[~2021-11-18 19:30 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-17 14:04 Alexander Sosedkin
2021-11-17 17:00 ` Érico Nogueira
2021-11-17 19:25   ` Alexander Sosedkin
2021-11-18 19:15     ` Érico Nogueira
2021-11-17 20:01   ` Jeffrey Walton
2021-11-18 19:21     ` Érico Nogueira [this message]
2021-11-18 19:41       ` Alexander Sosedkin
2021-11-18 19:42       ` Jeffrey Walton
2021-11-18 20:30         ` Rich Felker

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