Re: Bug in how capability inheritance is handled in "fs/exec.c", 2.3.99

From: Casey Schaufler (casey@sgi.com)
Date: Mon May 29 2000 - 19:03:16 EST


"Theodore Y. Ts'o" wrote:

> I think I actually overstated things when I said that "root shell" is
> prohibited. It doesn't have to run with PIE=(0,0,0). Linda was right
> on that score. (That is one way of doing things, but it's not the only
> way of doing things.)
>
> Still, even given that you're running with a shell with privileges,
> given that most executables have a PIE of (0,0,0), it means that they
> won't inherit any privileges by default. So "rm" would only get
> privileges if it was explicitly allowed to inherit DAC override (for
> example --- no reason to allow it to inherit CAP_SETUID, or CAP_SETPCAP,
> or any other privilege).

The first question a user of a pure capability system asks:

        Q: "How do I get root?"
        A: "su root -C all=eip" on Irix

It will be some time before everyone takes capabilities seriously.
But then again, who had a firewall up in 1992? We're changing our
computer usage patterns. Security is moving beyond the CrypoMagic
era. We may be slow, but we're not stoopid.

-- 

Casey Schaufler Manager, Trust Technology, SGI casey@sgi.com voice: (650) 933-1634

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