sysnetwork: allow dhcpcd to send and receive messages from systemd resolved

The dhcpcd can send DNS information to systemd-resolved to update
resolv.conf.

Fixes:
avc:  denied  { send_msg } for msgtype=method_call
interface=org.freedesktop.resolve1.Manager member=RevertLink
dest=org.freedesktop.resolve1 spid=340 tpid=345
scontext=system_u:system_r:dhcpc_t:s0-s15:c0.c1023
tcontext=system_u:system_r:systemd_resolved_t:s0-s15:c0.c1023
tclass=dbus permissive=0

avc:  denied  { send_msg } for msgtype=method_return dest=:1.6 spid=345
tpid=340 scontext=system_u:system_r:systemd_resolved_t:s0-s15:c0.c1023
tcontext=system_u:system_r:dhcpc_t:s0-s15:c0.c1023 tclass=dbus
permissive=0

Signed-off-by: Yi Zhao <[email protected]>

Author: yizhao1

policy/modules/system/sysnetwork.te

@@ -187,6 +187,10 @@ ifdef(`init_systemd',`
 	init_stream_connect(dhcpc_t)
 	init_get_all_units_status(dhcpc_t)
 	init_search_units(dhcpc_t)
+
+	optional_policy(`
+		systemd_dbus_chat_resolved(dhcpc_t)
+	')
 ')
 
 optional_policy(`