Messages in this thread | | | From | (Linus Torvalds) | Subject | Re: Direct access to hardware | Date | 22 Jul 2000 10:47:33 -0700 |
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In article <Pine.LNX.4.10.10007221822320.5862-100000@dax.joh.cam.ac.uk>, James Sutherland <jas88@cam.ac.uk> wrote: > >So much for the "root is god" claims made earlier, then. What about iopl() >and the like? IF capabilities can be used to block this (and similar), and >Andre's "sanity checking" for ATA is added, then surely it *IS* possible >to prevent root screwing the HDD (without replacing the kernel, at which >point all bets are off, of course).
What's the point?
If the system is secure, then adding sanity checking to the ATA code makes no difference: nobody gets to do anything improper anyway.
If the system is not secure, then adding sanity checking to the ATA code makes no difference: people who could use the ATA thing can use other things that are much more insidious.
The mechanism that everybody wants is _already_ there. It's called "permissions". No new driver code necessary.
If those permissions do not work, then they don't work, and adding last-minute band-aids makes no difference.
Just as a comparison, look at Windows. It takes the opposite approach: it has no real seurity, but a LOT of band-aids to avoid the "obvious" holes. Leaving it wide open.
Linus
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