Messages in this thread |  | | From | Keith Owens <> | Subject | Re: Local root exploit with kmod and modutils > 2.1.121 | Date | Wed, 15 Nov 2000 09:50:16 +1100 |
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On Tue, 14 Nov 2000 12:31:41 -0800, "Adam J. Richter" <adam@freya.yggdrasil.com> wrote: >>The only secure fix I can see is to add SAFEMODE=1 to modprobe's >>environment and change exec_modprobe. > > SAFEMODE may mean other things to other programs, so that
MOD_SAFEMODE.
> It would be much better to just add a command line option >to modprobe that request_module() would cause it treat the following
Changing the command line is not an option. Kernel 2.2 still runs with modutils 2.1.121, changing the request_module command line would break people using modutils 2.1.121 and force them to upgrade, AC would kill me. I needed a mechanism that would work with modutils 2.3 but have no effect on modutils 2.1.121, remember that 2.1.121 does not have this security exposure. It also had to work on 2.2 kernels because many people are using moditils 2.3 on 2.2 kernels. SGI ship a 2.2 kernel with devfs for their big machines, that needs modutils 2.3.
> Another possible approach would be to create a separate >/sbin/safe_modprobe. modprobe already behaves differently >based on whether argv[0] ends in "modprobe", "insmod", "depmod", >or "rmmod". So this would be in keeping with that convention. >It would also be trivial to retrofit old systems. Just have >some system boot script do: > > echo /sbin/safe_modprobe > /proc/sys/kernel/modprobe
I thought about that but it assumes that users will add that line to their scripts - not guaranteed. The fix needed a change that would automatically detect that safe mode was required and not rely on manual intervention. Especially with 30+ Linux distributions out there.
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