Re: [patch] remove MNT_NOEXEC check for PROT_EXEC mmaps

From: Arjan van de Ven
Date: Mon Sep 25 2006 - 07:17:30 EST

On Sat, 2006-09-23 at 14:30 +0400, Stas Sergeev wrote:
> Hi Andrew.
> I am not sure at all whether this patch is appreciated
> or not. The on-list query yielded no results, but I have
> to try. :)
> This patch removes the MNT_NOEXEC check for the PROT_EXEC
> mappings.

so you remove a security check ...

> That allows to mount tmpfs with "noexec" option
> without breaking the existing apps, which is what debian
> wants to do for sequrity reasons:

... to add a "security" feature?

sounds like the wrong tradeoff!

If you can mmap PROT_EXEC the "noexec" mount option doesn't mean
anything! Because a elf binary loader is easily written in
perl/shell/whatever, the kernel "x" bit is just a convenience there!
The PROT_EXEC check at least makes it a bit harder to do anything like
this; not impossible obviously

Arjan van de Ven

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