Messages in this thread |  | | Date | Sat, 13 Jul 1996 14:44:16 +0100 (BST) | From | Philip Blundell <> | Subject | Re: Misc Fixes |
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On Fri, 12 Jul 1996, Steffen Grunewald wrote:
> |> It doesnt help. The malicious module does > |> > |> unsigned long **ptr=(unsigned long **)&get_securelevel; > |> unsigned long *securelevelptr=ptr[SOME_CONSTANT]; > |> *securelevelptr=0; > > So we have to implement some `immutable memory' mechanism. once the > securelevel is set, it has to be (and the whole page) turned to readonly. > What a waste of valuable memory ! (I hear people complain about kernel > bloat once again :-)
No. As Alan said, we just have to disallow module loads. If you start allowing untrusted code to be inserted into the kernel, you can abandon all pretence at security.
Because modules run with kernel privilege, there's nothing you can do to keep them in check. If you set the page to be readonly, the rogue module can just set it back again.
P.
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