Re: [jail] Allowing root privledged users to renice

On Fri, May 25, 2012 at 10:23:53AM -0700, Julian Elischer wrote:
On 5/25/12 10:04 AM, Bjoern A. Zeeb wrote:
On 25. May 2012, at 16:48 , Sean Bruno wrote:

I've been toying with the idea of letting jails renice processes ... how
dangerous and/or stupid is this idea?

==== //depot/yahoo/ybsd_9/src/sys/kern/kern_jail.c#5 -
/home/seanbru/ybsd_9/src/sys/kern/kern_jail.c ====
270a271,275
+ int jail_allow_renice = 0;
+ SYSCTL_INT(_security_jail, OID_AUTO, allow_renice, CTLFLAG_RW,
+&jail_allow_renice, 0,
+ "Prison root can renice processes");

3857a3863,3865
+ case PRIV_SCHED_SETPRIORITY:
+ if (!jail_allow_renice)
+ return (EPERM);

I think sysctls are a bad idea given jails have per-jail flags these days.

Maybe also only allow re-nicing to be nicer but not less nice?
^^^^ for sure ! start a jail with it's max priority and the
root within can allow nicer priorities only..
you can always add priority from teh master (parent) environment outside.


Unless I seriously misunderstood something, that's the case right now.

That is, PRIV_SCHED_SETPRIORITY matters only if resulting nice parameter
would be lower.

--
Mateusz Guzik <mjguzik gmail.com>
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