re: modstat and kaslr

[matthew green <mrg%eterna.com.au@localhost>]

Maxime Villard writes:
> Hi,
> Here is a patch [1] that hides the addresses of the kernel modules when
> 'modstat -k' is entered by an unprivileged user. The current behavior is
> preserved for root.
> 
> The addresses currently leaked cannot be used to reconstruct the layout of
> the kernel, since the module VAs are embedded in bootspace.boot, whose location
> is independent from that of each of the remaining kernel segments.
> 
> But it's still good not to leak such information, to limit the surface for ROP
> and a few other things, and this, also in the non-kaslr case. Ok?
> 
> [1] http://m00nbsd.net/garbage/module/modstat.diff

seems reasonable and needed with kaslr.

i wonder if this is something that should be hidden if security.curtain
is set, or something else with a higher hardening mode than normal,
rather than generally, or on systems without kaslr.  a higher hardened
mode should hide them from root too, i guess.


.mrg.