Re: Modprobe local root exploit

[Malcolm Beattie <mbeattie@sable.ox.ac.uk>]

Keith Owens writes:
> All these patches against request_module are attacking the problem at
> the wrong point.  The kernel can request any module name it likes,
> using any string it likes, as long as the kernel generates the name.
> The real problem is when the kernel blindly accepts some user input and
> passes it straight to modprobe, then the kernel is acting like a setuid
> wrapper for a program that was never designed to run setuid.

Rather than add sanity checking to modprobe, it would be a lot easier
and safer from a security audit point of view to have the kernel call
/sbin/kmodprobe instead of /sbin/modprobe. Then kmodprobe can sanitise
all the data and exec the real modprobe. That way the only thing that
needs auditing is a string munging/sanitising program.

--Malcolm

-- 
Malcolm Beattie <mbeattie@sable.ox.ac.uk>
Unix Systems Programmer
Oxford University Computing Services
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