service_contexts: label service_contexts explicitly

The label applies to all service_contexts regardless of their location.
This also lets us track the service_contexts usage and limit access to
the files for the corresponding object manager alone.

Bug: 36002427
Test: Boot sailfish and observe no denials for 'serice_contexts'
Test: cts-tradefed run singleCommand cts --skip-device-info \
          --skip-preconditions --skip-connectivity-check \
          --abi arm64-v8a --module CtsSecurityHostTestCases \
          -t android.security.cts.SELinuxHostTest#testAospServiceContexts

Change-Id: I97fc8b24bc99ca5c00d010fb522cd39a35572858
Signed-off-by: Sandeep Patil <sspatil@google.com>

private/adbd.te

@@ -100,6 +100,7 @@ allow adbd system_file:file r_file_perms;
 allow adbd selinuxfs:dir r_dir_perms;
 allow adbd selinuxfs:file r_file_perms;
 allow adbd kernel:security read_policy;
+allow adbd service_contexts_file:file r_file_perms;
 
 allow adbd surfaceflinger_service:service_manager find;
 allow adbd bootchart_data_file:dir search;

private/file_contexts

@@ -50,8 +50,8 @@
 /nonplat_seapp_contexts     u:object_r:rootfs:s0
 /plat_seapp_contexts     u:object_r:rootfs:s0
 /sepolicy           u:object_r:rootfs:s0
-/plat_service_contexts   u:object_r:rootfs:s0
-/nonplat_service_contexts   u:object_r:rootfs:s0
+/plat_service_contexts   u:object_r:service_contexts_file:s0
+/nonplat_service_contexts   u:object_r:service_contexts_file:s0
 
 ##########################
 # Devices
@@ -250,12 +250,14 @@
 /system/bin/vr_wm                u:object_r:vr_wm_exec:s0
 /system/bin/hw/android\.hidl\.allocator@1\.0-service          u:object_r:hal_allocator_default_exec:s0
 /system/etc/selinux/plat_property_contexts  u:object_r:property_contexts_file:s0
+/system/etc/selinux/plat_service_contexts  u:object_r:service_contexts_file:s0
 
 #############################
 # Vendor files
 #
 /vendor(/.*)?		u:object_r:system_file:s0
 /vendor/etc/selinux/nonplat_property_contexts   u:object_r:property_contexts_file:s0
+/vendor/etc/selinux/nonplat_service_contexts    u:object_r:service_contexts_file:s0
 
 #############################
 # OEM and ODM files

public/file.te

@@ -259,6 +259,9 @@ type gps_control, file_type;
 # property_contexts file
 type property_contexts_file, file_type;
 
+# service_contexts file
+type service_contexts_file, file_type;
+
 # Allow files to be created in their appropriate filesystems.
 allow fs_type self:filesystem associate;
 allow sysfs_type sysfs:filesystem associate;

public/servicemanager.te

@@ -11,7 +11,8 @@ type servicemanager_exec, exec_type, file_type;
 allow servicemanager self:binder set_context_mgr;
 allow servicemanager { domain -init }:binder transfer;
 
-r_dir_file(servicemanager, rootfs)
+# Access to all (system and vendor) service_contexts
+allow servicemanager service_contexts_file:file r_file_perms;
 
 # Check SELinux permissions.
 selinux_check_access(servicemanager)