Extending MADV_PROTECT

[Konstantin Belousov]

On Fri, Jul 12, 2013 at 05:48:57PM -0400, John Baldwin wrote:
> On Friday, June 28, 2013 2:46:01 pm John Baldwin wrote:
> > Ok, there isn't really a clear consensus here, but I need a system call to let
> > me toggle this flag on existing processes.
> > 
> > One reason I don't like the procctl() approach is I am uneasy about forcing
> > a certain behavior for how commands treat pgid (first-fail vs best-effort).
> > I guess it can always change in the future so that isn't completely unsolvable.
> > 
> > I guess I am fine just making it use hardcoded sizes instead of full-blown
> > ioctl encoding.
> 
> Ok, I have updated patches for this for HEAD.  I have not yet implemented the
> inheritance bits because I'm loathe to add the first bit to a p_flag2. :-P
> However, if that's the best course of action I suppose we can do that.
> 
> The kernel patch is at www.freebsd.org/~jhb/patches/procctl.patch
> 
> The patch for the protect binary is at www.freebsd.org/~jhb/patches/protect.patch
> 

It seems that p_cansee() is called twice, once in kern_procctl(), and
then in protect_setchild().

Is AUE_WAIT6 the correct audit event id for procctl ?

I thought proposing to use pget() for P_PID case in kern_procctl(), but
indeed open coding of the process lookup is easier, since otherwise
you would need to move proctree_lock acquisition to P_PGID.

Why do you need PPROT_CLEAR ?  If you do need the flag, would it be better
to assign a non-zero value to it ?
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