Minimize public policy

Ideally, public should only contain APIs (types / attributes) for
vendor. The other statements like allow/neverallow/typeattributes are
regarded as implementation detail for platform and should be in private.

Bug: 232023812
Test: m selinux_policy
Test: diff <(git diff --staged | grep "^-" | cut -b2- | sort) \
           <(git diff --staged | grep "^+" | cut -b2- | sort)
Test: remove comments on plat_sepolicy.cil, replace base_typeattr_*
      to base_typeattr and then compare old and new plat_sepolicy.cil
Change-Id: I5e7d2da4465ab0216de6bacdf03077d37f6ffe12
diff --git a/private/servicemanager.te b/private/servicemanager.te
index 5a69a43..7a5bf51 100644
--- a/private/servicemanager.te
+++ b/private/servicemanager.te
@@ -12,3 +12,39 @@
 
 # servicemanager is using apex_info via libvintf
 use_apex_info(servicemanager)
+
+# Note that we do not use the binder_* macros here.
+# servicemanager is unique in that it only provides
+# name service (aka context manager) for Binder.
+# As such, it only ever receives and transfers other references
+# created by other domains.  It never passes its own references
+# or initiates a Binder IPC.
+allow servicemanager self:binder set_context_mgr;
+allow servicemanager {
+  domain
+  -init
+  -vendor_init
+  -hwservicemanager
+  -vndservicemanager
+}:binder transfer;
+
+allow servicemanager service_contexts_file:file r_file_perms;
+
+allow servicemanager vendor_service_contexts_file:file r_file_perms;
+
+# nonplat_service_contexts only accessible on non full-treble devices
+not_full_treble(`allow servicemanager vendor_service_contexts_file:file r_file_perms;')
+
+add_service(servicemanager, service_manager_service)
+allow servicemanager dumpstate:fd use;
+allow servicemanager dumpstate:fifo_file write;
+
+# Check SELinux permissions.
+selinux_check_access(servicemanager)
+
+allow servicemanager kmsg_device:chr_file rw_file_perms;
+
+recovery_only(`
+  # Read VINTF files.
+  r_dir_file(servicemanager, rootfs)
+')