selinux - allow netd to create tun device and pass it in via open fd across execve to clatd cli

This is needed to resolve some race conditions between clatd startup and interface naming/numbering.

This resolves:
  type=1400 audit(): avc: denied { read write } for comm="Binder:820_4" name="tun" dev="tmpfs" ino=20564 scontext=u:r:netd:s0 tcontext=u:object_r:tun_device:s0 tclass=chr_file
  type=1400 audit(): avc: denied { open } for comm="Binder:820_4" path="/dev/tun" dev="tmpfs" ino=20564 scontext=u:r:netd:s0 tcontext=u:object_r:tun_device:s0 tclass=chr_file
  type=1400 audit(): avc: denied { ioctl } for comm="Binder:820_4" path="/dev/tun" dev="tmpfs" ino=20564 ioctlcmd=0x54ca scontext=u:r:netd:s0 tcontext=u:object_r:tun_device:s0 tclass=chr_file
  type=1400 audit(): avc: denied { create } for comm="Binder:820_4" scontext=u:r:netd:s0 tcontext=u:r:netd:s0 tclass=tun_socket

Test: built/installed on crosshatch with netd->clatd tunfd passing and observed no selinux denials
Bug: 65674744
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Ib501c755e11ec8a3a22c8aa333b5af7ec0bff306
1 file changed