Subject: Re: more on non-executable mappings vs. emulations
To: Christos Zoulas <>
From: Chuck Silvers <>
List: tech-kern
Date: 07/12/2004 08:12:41
On Mon, Jul 12, 2004 at 12:32:21PM +0000, Christos Zoulas wrote:
> I agree that we should not make kernels insecure by default in order to
> please broken emulations. On the other hand, we should document and
> explain why emulations break and provide a sysctl to let broken emulated
> programs run until we supply the tools you mention above. This sysctl
> should default to "off" and users should be strongly cautioned against
> turning it "on".

well, the tools will be much easier to write than the sysctl,
so I'm only going to do the tools.  I'd prefer that the sysctl thing
never actually be done, since it opens a big can of worms.

the ppc ELF tool should be trivial, I'll write it this evening.

as for the sparc a.out issue, it occurred to me on my morning walk that
it may be possible to have mprotect() the relevant parts of itself
before it needs to execute the incorrectly mapped instructions.
I'll look into this tonight also.