Messages in this thread | | | Date | Thu, 03 Jun 2004 16:54:39 -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:
>>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. > > > Good point. > > But that only applies to the NX personality bit. For the uname emulation > it is not an issue. > > So maybe the dropping on exec should only zero a few selected > personality bits, but not all.
True.
>>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. > > > Don't think we should require an LSM module for that. That's > far overkill.
I'm not suggesting a new LSM module. I'm suggesting modifying the existing LSM code to handle this cleanly. We already have a function (security_bprm_secureexec) that does something like this, and, in fact, it's probably the right thing to test here.
I'm currently compiling a new patch (modified from my last caps cleanup) that makes a new bitfield for this stuff. I don't know if it's worth applying, but I'll send it off to Andrew once I convince myself it works.
--Andy
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