Re: [PATCH] kernel: make /proc/kallsyms mode 400 to reduce ease of attacking

[Willy Tarreau <w@1wt.eu>]

On Fri, Nov 19, 2010 at 12:04:47PM -0800, Linus Torvalds wrote:
> On Fri, Nov 19, 2010 at 11:58 AM,  <david@lang.hm> wrote:
> >
> > how far back do we need to maintain compatibility with userspace?
> >
> > Is this something that we can revisit in a few years and lock it down then?
> 
> The rule is basically "we never break user space".
> 
> But the "out" to that rule is that "if nobody notices, it's not
> broken". In a few years? Who knows?
> 
> So breaking user space is a bit like trees falling in the forest. If
> there's nobody around to see it, did it really break?

FWIW, I appreciate a lot that non-breaking rule. I have some testing
machines which boot from PXE or USB on a file-system with some old
tools and libc, that are both 2.4 and 2.6 compatible. Everything works
like a charm, the only point of care was to have both module-init-tools
and modutils (obviously) but even that integrates smoothly.

I know quite a lot of people who never replace user-space but only
kernels on their systems, so this non-breaking rule is much welcome !

Willy