sepolicy: Allow apps to get info from priv_app by ashmem

This is used to address a CTS testcase failure. This CTS
testcase need to access the content of Contact, some data
from ContactProvider is transfered through ashmem.

Currently ashmem is backed by the tmpfs filesystem, ContactProvider
in android run as a priv_app, so the file context of the ashmem
created by ContactProvider is priv_app_tmpfs. CTS runs as an
untrusted_app, need to be granted the read permission to the
priv_app_tmpfs files.

Bug: 117961216

[Android Version]:
android_p_mr0_r0

[Kernel Version]:
4.19.0-rc8

[CTS Version]:
cts-9.0_r1

[Failed Testcase]:
com.android.cts.devicepolicy.ManagedProfileTest#testManagedContactsPolicies

[Error Log]:
11-11 11:15:50.479 12611 12611 W AndroidTestSuit: type=1400 audit(0.0:811):
avc: denied { read } for path=2F6465762F6173686D656D202864656C6574656429
dev="tmpfs" ino=174636 scontext=u:r:untrusted_app:s0:c113,c256,c522,c768
tcontext=u:object_r:priv_app_tmpfs:s0:c522,c768 tclass=file permissive=0

[Test Result With This Patch]:
PASS

Change-Id: I45efacabe64af36912a53df60ac059889fde1629

private/app.te

@@ -6,6 +6,10 @@ allow appdomain zygote_tmpfs:file read;
 # ashmem, e.g. battery stats.
 allow appdomain system_server_tmpfs:file read;
 
+# Get info from priv_app through ashmem, such as contact
+# info etc.
+allow appdomain priv_app_tmpfs:file read;
+
 neverallow appdomain system_server:udp_socket {
         accept append bind create ioctl listen lock name_bind
         relabelfrom relabelto setattr shutdown };

private/mls

@@ -57,7 +57,7 @@ mlsconstrain dir_file_class_set { create relabelfrom relabelto }
 mlsconstrain dir { open search setattr rename add_name remove_name reparent rmdir }
 	     ( (t2 != app_data_file and t2 != privapp_data_file ) or l1 dom l2 or t1 == mlstrustedsubject);
 mlsconstrain { file lnk_file sock_file } { open setattr unlink link rename }
-	     ( (t2 != app_data_file and t2 != privapp_data_file) or l1 dom l2 or t1 == mlstrustedsubject);
+	     ( (t2 != app_data_file and t2 != privapp_data_file and t2 != priv_app_tmpfs) or l1 dom l2 or t1 == mlstrustedsubject);
 
 #
 # Constraints for file types other than app data files.
@@ -69,7 +69,7 @@ mlsconstrain dir { read getattr search }
 	     (t2 == app_data_file or t2 == privapp_data_file or l1 dom l2 or t1 == mlstrustedsubject or t2 == mlstrustedobject);
 
 mlsconstrain { file lnk_file sock_file chr_file blk_file } { read getattr execute }
-	     (t2 == app_data_file or t2 == privapp_data_file or l1 dom l2 or t1 == mlstrustedsubject or t2 == mlstrustedobject);
+	     (t2 == app_data_file or t2 == privapp_data_file or t2 == priv_app_tmpfs or l1 dom l2 or t1 == mlstrustedsubject or t2 == mlstrustedobject);
 
 # Write operations: Subject must be equivalent to the object unless the
 # subject or the object is trusted.
@@ -77,7 +77,7 @@ mlsconstrain dir { write setattr rename add_name remove_name reparent rmdir }
 	     (t2 == app_data_file or t2 == privapp_data_file or l1 eq l2 or t1 == mlstrustedsubject or t2 == mlstrustedobject);
 
 mlsconstrain { file lnk_file sock_file chr_file blk_file } { write setattr append unlink link rename }
-	     (t2 == app_data_file or t2 == privapp_data_file or l1 eq l2 or t1 == mlstrustedsubject or t2 == mlstrustedobject);
+	     (t2 == app_data_file or t2 == privapp_data_file or t2 == priv_app_tmpfs or l1 eq l2 or t1 == mlstrustedsubject or t2 == mlstrustedobject);
 
 # Special case for FIFOs.
 # These can be unnamed pipes, in which case they will be labeled with the