Re: swapfile security weakeness

Pavel Machek (pavel@bug.ucw.cz)
Fri, 6 Nov 1998 00:13:13 +0100


Hi!

> i've found that active swapfile could be deleted, which is
> IMHO very dangerous (set immutable flag on in sys_swapon
> call?). Also,

Why? Under unix files disappear at close, so everything should be just
fine. (Too lazy to check myself, did you try it?)

Even if this was a problem (I think it is not), there are much better
ways how to kill machine when you are root (cat /dev/zero > /dev/hda).

> sys_swapon should check whether owner of swapfile is root and is readable
> only to root ( memory readableby anyone? hmm...)

What does this have to do with kernel? If you think it is a problem
(repeating, root can chmod 666 /etc/passwd, or chmod +s /bin/bash;
that is bad idea, also), patch mkswap/swapon. Still I do not think it
is neccessary.

Pavel

-- 
I'm really pavel@atrey.karlin.mff.cuni.cz. 	   Pavel
Look at http://atrey.karlin.mff.cuni.cz/~pavel/ ;-).

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