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Date:      Sat, 02 Sep 2000 15:07:08 -0700
From:      Peter Wemm <peter@netplex.com.au>
To:        Poul-Henning Kamp <phk@critter.freebsd.dk>
Cc:        Brian Somers <brian@Awfulhak.org>, "Jacques A. Vidrine" <n@nectar.com>, Dan Nelson <dnelson@emsphone.com>, sthaug@nethelp.no, ume@FreeBSD.ORG, arch@FreeBSD.ORG
Subject:   Re: setuid ssh should die (Re: Request for review: nsswitch) 
Message-ID:  <200009022207.e82M78G32995@netplex.com.au>
In-Reply-To: <41784.967926245@critter> 

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Poul-Henning Kamp wrote:
> In message <200009022015.e82KFN740808@hak.lan.Awfulhak.org>, Brian Somers wri
    te
> s:
> >> On Sat, Sep 02, 2000 at 02:58:22PM -0500, Dan Nelson wrote:
> >> > Rather, it's so it can read the host key, which is only readable by
> >> > root.
> >> 
> >> We're talking about ssh, not sshd.
> >> 
> >> IMHO, ssh should be mode 0555.  I have to change this all the time on
> >> my machines, since I often socksify ssh.
> >
> >Yes, a make.conf variable would be in order, defaulting to 0555 in 
> >line with FallBackToRsh being set to no in /etc/ssh/ssh_config. 
> 
> Uhm, how about a ssh_config variable where you tell it to drop
> the setuid bit right away, wouldn't that work ?

It's too late by then.  issetugid() is sticky and stays on forever.

Perhaps we can add a clearsetugid() syscall that apps can call when they
are prepared to guarantee that things like libc getpwent() don't have a
cached copy of the priviliged master.passwd in memory that a coredump might
otherwise expose or ptrace() could extract.

On the other hand, I don't think applications *can* make this guarantee -
they have no way to be *certain* that libc hasn't cached something
sensitive.

Cheers,
-Peter
--
Peter Wemm - peter@FreeBSD.org; peter@yahoo-inc.com; peter@netplex.com.au
"All of this is for nothing if we don't go to the stars" - JMS/B5



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