Re: mmap_min_addr and your local LSM (ok, just SELinux)

[Pavel Machek <pavel@ucw.cz>]

Hi!

> Brad Spengler recently pointed out that the SELinux decision on how to
> handle mmap_min_addr in some ways weakens system security vs on a system
> without SELinux (and in other ways can be stronger).  There is a trade
> off and a reason I did what I did but I would like ideas and discussion
> on how to get the best of both worlds.
> 
> With SELinux mapping the 0 page requires an SELinux policy permission,
> mmap_zero.  Without SELinux mapping the 0 page requires CAP_SYS_RAWIO.
> Note that CAP_SYS_RAWIO roughly translates to uid=0 since noone really
> does interesting things with capabilities.

I wonder if cap_sys_rawio is right capability for this..? rawio
normally grants you kernel-llevel access, so you don't want to give it
to wine. But maybe if it checked cap_sys_nice or some new capability,
we could reasonably give that to wine, and problem would be gone?

cap_sys_obscure_features ?

(I guess vm86 mode should fall under that, too :-)

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