Allow netd-spawned domains to use inherited netd unix_dgram_socket.

Resolves denials such as:
 avc:  denied  { read write } for  pid=4346 comm="hostapd" path="socket:[7874]" dev="sockfs" ino=7874 scontext=u:r:hostapd:s0 tcontext=u:r:netd:s0 tclass=unix_dgram_socket
 avc:  denied  { read write } for  pid=4348 comm="dnsmasq" path="socket:[7874]" dev="sockfs" ino=7874 scontext=u:r:dnsmasq:s0 tcontext=u:r:netd:s0 tclass=unix_dgram_socket

Change-Id: Ie82f39c32c6e04bc9ef1369ca787cf80b3b4141c
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>

dnsmasq.te

@@ -20,3 +20,4 @@ allow dnsmasq netd:netlink_kobject_uevent_socket { read write };
 allow dnsmasq netd:netlink_nflog_socket { read write };
 allow dnsmasq netd:netlink_route_socket { read write };
 allow dnsmasq netd:unix_stream_socket { read write };
+allow dnsmasq netd:unix_dgram_socket { read write };

hostapd.te

@@ -17,8 +17,10 @@ allow hostapd wpa_socket:dir create_dir_perms;
 allow hostapd wpa_socket:sock_file create_file_perms;
 allow hostapd netd:fd use;
 allow hostapd netd:udp_socket { read write };
+allow hostapd netd:fifo_file { read write };
+# TODO: Investigate whether these inherited sockets should be closed on exec.
 allow hostapd netd:netlink_kobject_uevent_socket { read write };
 allow hostapd netd:netlink_nflog_socket { read write };
 allow hostapd netd:netlink_route_socket { read write };
 allow hostapd netd:unix_stream_socket { read write };
-allow hostapd netd:fifo_file { read write };
+allow hostapd netd:unix_dgram_socket { read write };