Messages in this thread | | | Date | Thu, 03 Jun 2004 16:01:57 -0700 | From | Andy Lutomirski <> | Subject | Re: [announce] [patch] NX (No eXecute) support for x86, 2.6.7-rc2-bk2 |
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Andi Kleen wrote: > On Thu, 3 Jun 2004 14:44:48 +0200 > Ingo Molnar <mingo@elte.hu> wrote: > > > >>- in exec.c, since address-space executability is a security-relevant >>item, we must clear the personality when we exec a setuid binary. I >>believe this is also a (small) security robustness fix for current >>64-bit architectures. > > > I'm not sure I like that. This means I cannot earily force an i386 uname > or 3GB address space on suid programs anymore on x86-64. > > While in theory it could be a small security problem I think the utility > is much greater. > > It's hard to see how setting NX could cause a security hole. The program > may crash, but it is unlikely to be exploitable.
The whole point of NX, though, is that it prevents certain classes of exploits. If a setuid binary is vulnerable to one of these, then Ingo's patch "fixes" it. Your approach breaks that.
I don't like Ingo's fix either, though. At least it should check CAP_PTRACE or some such. A better fix would be for LSM to pass down a flag indicating a change of security context. I'll throw that in to my caps/apply_creds cleanup, in case that ever gets applied.
--Andy
> > -Andi
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