Messages in this thread | | | Subject | Re: Out of tree module using LSM | From | Valdis.Kletnieks@vt ... | Date | Thu, 29 Nov 2007 15:56:28 -0500 |
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On Thu, 29 Nov 2007 14:45:51 EST, Jon Masters said: > Ah, but I could write a sequence of pages that on their own looked > garbage, but in reality, when executed would print out a copy of the > Jargon File in all its glory. And if you still think you could look for > patterns, how about executable code that self-modifies in random ways > but when executed as a whole actually has the functionality of fetchmail > embedded within it? How would you guard against that?
So, just because Fred Cohen showed in his PhD thesis that *perfect* virus/malware scanning is equivalent to the Turing Halting Problem, we should abandon efforts to make a 99.9998% workable system?
Yes, most of these schemes *can* be bypassed because some malicious code does a mmap() or similar trick. But what is being overlooked here is that in most cases, what is *desired* is a way to filter things being handled by *non* malicious code. Yeah, sure, a shar archive can contain a binary that does evil things - but if we stop /bin/cp from copying the file that has the evil in it, it's a non-issue.
Let's get real here guys - trying to do *absolutely perfect* security is pointless. You want to do security that reduces your *total* cost - and in most cases this means "pretty good security" that stops "almost all issues".
As Linus reminds us once in a while - the perfect is the enemy of the good. In this case, we don't *need* to be perfect - we only need to be noticably better than another well-known operating system that isn't even very good at it. [unhandled content-type:application/pgp-signature] | |