A kernel security hole [LWN.net]

A kernel security hole

Posted Jan 17, 2008 9:12 UTC (Thu) by filipjoelsson (subscriber, #2622)
In reply to: A kernel security hole by jamesm
Parent article: A kernel security hole

So, what you're saying is that implementing the same checks twice independently significantly
lowers the risk of this kind of mistake, right? (If the chance of a mistake is 1:1000 - the
chance of the same mistake in both layers is 1:1000000.)

Though this is clearly true, doesn't it implicate a bit of a performance problem? And is every
relevant check implemented twice (ie once in code and once for the security module)?

Or am I completely misunderstanding something?

(Log in to post comments)

A kernel security hole

Posted Jan 17, 2008 10:04 UTC (Thu) by jamesm (guest, #2273) [Link]

I don't know if you can generalize things in that way, as it is essentially a side effect of having independent DAC and MAC mechanisms that has been observed a couple of times. Yes, there is a performance hit when you have multiple security mechanisms, but MAC is typically expected to have some impact.