Re: setuid scripts (was Re: proc fs and shared pids)

Matthias Urlichs (smurf@smurf.noris.de)
Tue, 17 Sep 1996 06:14:59 +0100

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In linux.dev.kernel, article <Pine.LNX.3.95.960906174146.31788A-100000@xarius.demon.co.uk>,
Darren J Moffat <darren@xarius.demon.co.uk> writes:
>
> $ setuidexec /bin/sh
> Syntax error while executing setuidexec
> Usage: #! setuidexec <shell>
>
> The reason for this is the setuidexec program (as posted in this list)
> does the /dev/fd hack that Solaris 2.x does exactly _and_ checks the
> permisons of the script _and_ creates a minimal standard environment _and_
> can't be run unless it is called via a #! mechanism.

But the only way to check the latter is via looking at argv[]. Thus, this
check can be defeated by calling suidexec with a trivial C wrapper.

Nonono... setuidexec _must_ check whether the file system the script is on
is mounted with nosuid/nosgid.

-- DIDI ... is that a MARTIAN name, or, are we in ISRAEL? -- Zippy the Pinhead

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