Subject: Re: PROT_EXEC mappings of vnodes -> VTEXT
To: Ben Harris <>
From: Jason R Thorpe <>
List: tech-kern
Date: 10/30/2001 06:45:36
On Tue, Oct 30, 2001 at 11:04:34AM +0000, Ben Harris wrote:

 > In article <> you write:
 > >but I really don't think we should allow unpriviledged users
 > >to cause any file they can read to become read-only just by
 > >mapping it with PROT_EXEC.  the VTEXT flag was originally used
 > >just for the read-only part, I was overloading it when I used it
 > >for affecting paging behaviour.
 > Hmm.  What's the reasoning behind protecting executables against being
 > overwritten, and why doesn't it apply to shared libraries as well?

Yah, I'm a little fuzzy on this, too.  If the idea is that you don't
want the underlying file changing while you deamand-page from it, then
that applies to shared libraries, too.

        -- Jason R. Thorpe <>