From: Vitaliy Makkoveev <mvs@openbsd.org>
Subject: Re: sysctl: unlock IPCTL_MRTPROTO
To: Alexander Bluhm <bluhm@openbsd.org>
Cc: tech@openbsd.org
Date: Mon, 23 Jun 2025 18:40:45 +0300

On Mon, Jun 23, 2025 at 04:30:06PM +0200, Alexander Bluhm wrote:
> On Mon, Jun 23, 2025 at 04:14:22PM +0300, Vitaliy Makkoveev wrote:
> > Read-only access from sysctl(2) interface.
> 
> Maybe IPCTL_MRTPROTO is a leftover from routing daemon support in
> kernel that was deleted.  As we might revive that code from attic
> some day, let's keep that sysctl.  I remember fixing something in
> netstat for the IPv6 case.
> 
> Your unlocking code is correct.  Could you add a [I] comment in
> ip_mroute.c?
> 
> OK bluhm@
> 

The `ip6_mrtproto' is also immutable. Will update it too with the
IPV6CTL_MRTPROTO diff.

> > Index: sys/netinet/ip_input.c
> > ===================================================================
> > RCS file: /cvs/src/sys/netinet/ip_input.c,v
> > diff -u -p -r1.411 ip_input.c
> > --- sys/netinet/ip_input.c	23 Jun 2025 09:16:32 -0000	1.411
> > +++ sys/netinet/ip_input.c	23 Jun 2025 13:12:21 -0000
> > @@ -116,12 +116,12 @@ const struct sysctl_bounded_args ipctl_v
> >  	{ IPCTL_FORWARDING, &ip_forwarding, 0, 2 },
> >  	{ IPCTL_SENDREDIRECTS, &ip_sendredirects, 0, 1 },
> >  	{ IPCTL_DIRECTEDBCAST, &ip_directedbcast, 0, 1 },
> > -};
> > -
> > -const struct sysctl_bounded_args ipctl_vars[] = {
> >  #ifdef MROUTING
> >  	{ IPCTL_MRTPROTO, &ip_mrtproto, SYSCTL_INT_READONLY },
> >  #endif
> > +};
> > +
> > +const struct sysctl_bounded_args ipctl_vars[] = {
> >  	{ IPCTL_DEFTTL, &ip_defttl, 0, 255 },
> >  	{ IPCTL_IPPORT_FIRSTAUTO, &ipport_firstauto, 0, 65535 },
> >  	{ IPCTL_IPPORT_LASTAUTO, &ipport_lastauto, 0, 65535 },
> > @@ -1830,6 +1830,9 @@ ip_sysctl(int *name, u_int namelen, void
> >  	case IPCTL_FORWARDING:
> >  	case IPCTL_SENDREDIRECTS:
> >  	case IPCTL_DIRECTEDBCAST:
> > +#ifdef MROUTING
> > +	case IPCTL_MRTPROTO:
> > +#endif
> >  		return (sysctl_bounded_arr(
> >  		    ipctl_vars_unlocked, nitems(ipctl_vars_unlocked),
> >  		    name, namelen, oldp, oldlenp, newp, newlen));
>