[lkml]   [2005]   [Jan]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: thoughts on kernel security issues

* John Richard Moser <> wrote:

> Split-out portions of PaX (and of ES) don't make sense. [...]

which shows that you dont know the exec-shield patch at all, nor those
split-out portions. At which point it becomes pretty pointless to
discuss any technical details, dont you think?

> PT_GNU_STACK annoys me :P I'm more interested in 1) PaX' full set of
> markings (-ps for NX, -m for mprotect(), r for randmmap, x for
> randexec), [...]
> I guess it works on Exec Shield, but it frightens me that I have to
> audit every library an executable uses for a PT_GNU_STACK marking to
> see if it has an executable stack.

here there are two misconceptions:

1) you claim that the manual setting of markings is better than the
_automatic_ setting of markings in Fedora. Manual setting is a support
and maintainance nightmare, there can be false positives and false
negatives as well. Also, manual setting of markings assumes code review
or 'does this application break' type of feedback - neither is as
reliable as automatic detection done by the compiler.

2) you claim that you have to audit everything. You dont have to. It's
all automatic. _Fedora developers_ (not you) then check the markings and
reduce the number of executable stacks as much as possible.

> [...] ES' NX approximation fails if you relieve protections on a
> higher mapping-- which confuses me, isn't vsyscall() a high-address
> executable mapping, which would disable NX protection for the full
> address space?

another misconception. Read the patch and you'll see how it's solved.

> Aside from that, I just trust the PaX developer more. He's already
> got a more developed product; he's a security developer instead of a
> scheduler developer; and he reads CPU manuals for breakfast.

this is your choice, and i respect it. Please show the same amount of
respect for the choice of others as well, without badmouthing anything
just because their choice is different from yours.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 14:09    [W:0.169 / U:1.612 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site