cap_sysctlbyname for hw.vmm.destroy

[Mark Johnston]

On Wed, Apr 28, 2021 at 02:30:26PM +0300, Ionuț Mihalache wrote:
> I tried to test the example from the documentation between here [1] and
> here [2]. The code stops here [3].

I think you're referencing an old version of the cap_sysctl man page?
See the example from the copy in your repo:
https://github.com/FreeBSD-UPB/freebsd-src/blob/3a08ffe4839de9b8396b1760f1dc42b066428807/lib/libcasper/services/cap_sysctl/cap_sysctl.3#L122
In particular, when setting limits consumers should not be building
nvlists directly.

> [1] -
> https://github.com/FreeBSD-UPB/freebsd-src/blob/3a08ffe4839de9b8396b1760f1dc42b066428807/usr.sbin/bhyve/bhyverun.c#L1538
> [2] -
> https://github.com/FreeBSD-UPB/freebsd-src/blob/3a08ffe4839de9b8396b1760f1dc42b066428807/usr.sbin/bhyve/bhyverun.c#L1585
> [3] -
> https://github.com/FreeBSD-UPB/freebsd-src/blob/3a08ffe4839de9b8396b1760f1dc42b066428807/usr.sbin/bhyve/bhyverun.c#L1581
> 
> În lun., 26 apr. 2021 la 20:40, Mark Johnston <markj at freebsd.org> a scris:
> 
> > On Mon, Apr 26, 2021 at 05:16:14PM +0300, Ionuț Mihalache wrote:
> > > Hello,
> > >
> > > I am working on adding capsicum support for the bhyve snapshot feature.
> > At
> > > the end of the suspend process, the guest should be destroyed and the
> > code
> > > handles this part with a sysctlbyname call which is not working in
> > > capability mode. I don't know what is the problem but even when using
> > > cap_sysctlbyname I still get the same error code (EPERM). I tried the
> > > example from the documentation aswell [1] and still the same error code.
> > > What could be the problem? I have a FreeBSD13 host and a FreeBSD13 guest.
> >
> > I'm not sure why it would happen unless the casper process is somehow
> > running as a non-root user.  Can you share the code you're testing
> > somewhere?
> >