Re: [RFC][PATCH] Randomize kernel base address on boot

[Ingo Molnar]

* Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:

> If you compile your own kernel version, you're already home free, 
> and load-time randomization is pointless.

Most successful exploits work in two steps: first a local exploit 
(weak password with a user, stupid script escaping bug, or a buffer 
overflow somewhere), then a local kernel exploit to gain root and 
kernel access. (for a rootkit and what not)

Straight remote root exploits are pretty rare - and per system 
relinking only protects against that.

The problem with your relinking solution is that a local attacker can 
easily figure out where the kernel is. So this does not protect 
against the more common break-in scenario.

Kernel image randomization makes this last step really 
indeterministic and thus dangerous to attackers.

Thanks,

	Ingo
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