MFC r326362:
Disallow TUN and TAP character device IOCTLs to modify the network device
type to any value. This can cause page faults and panics due to accessing
uninitialized fields in the "struct ifnet" which are specific to the network
device type.

Found by: jau@iki.fi
PR: 223767
Sponsored by: Mellanox Technologies

MFH r274083:
convert .Nm to proper .Xr's...

MFH r275298:
Cross reference tap(4) and tun(4) and include a short explanation as
to how they differ. This will assist users in selecting which interface
is more appropriate for their purposes.

No objection: jmg (r274083)
Approved by: grog (co-mentor)

MFH r274083:
convert .Nm to proper .Xr's...

MFH r275298:
Cross reference tap(4) and tun(4) and include a short explanation as
to how they differ. This will assist users in selecting which interface
is more appropriate for their purposes.

No objection: jmg (r274083)
Approved by: grog (co-mentor)