Messages in this thread | | | Date | Mon, 4 Nov 2002 09:39:27 -0500 | From | "Theodore Ts'o" <> | Subject | Re: Filesystem Capabilities in 2.6? |
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On Sun, Nov 03, 2002 at 01:37:19AM -0500, Alexander Viro wrote: > > In other words, it would actually make perfect sense to have > > > > -r-sr-sr-x 1 nobody mail 451280 Apr 8 2002 /usr/bin/sendmail > > > > mount --bind --capability=chown,bindlow /usr/bin/sendmail /usr/bin/sendmail > > *blam* > > Congratulations with potential crapload of security holes - now anyone > who'd compromised a process running as nobody can chmod the damn thing > and modify it. > > And that is the reason why suid-nonroot is bad. It creates a class of > binaries that can easily give you a root compromise if one of them has > an exploit - even if that one is never run by root.
This is solved by some implementations of POSIX capabilities by zapping any capabilities if the executible is modified --- just as some Unix systems zap the setuid bit if the executable is modified. It addresses specifically the problem that you've raised.
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