Re: Linus replies. Re: Computer: Can We Make Operating Systems Reliable and Secure?// SAS

[Bas Wijnen]

On Thu, May 11, 2006 at 04:44:40PM -0400, Jonathan S. Shapiro wrote:
> I approve of safe programming languages (which doesn't necessarily
> require a JVM). I just think that they aren't a complete solution by
> themselves.

In particular, safe languages will not generate code which shares things which
should not be shared.  However, they cannot guarantee that there are no bugs
in the code.  And if some cracker takes over the program through such a bug,
you cannot assume that he will just use the same limits on the code that the
compiler would use.  In fact you can be pretty sure he won't.  And without
hardware protection, that means any bug compromises the whole machine.  I
wouldn't call that secure...

Yes, these things can be enforced with a virtual machine.  But I don't
actually see why a virtual machine would be better than a real machine,
considering the performance penalty a virtual machine gives.  I have no
numbers, but I don't think it's comparable to the performance you lose because
you can't share more flexible than per page.

Thanks,
Bas

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