Revert "Revert "SELinux policy changes for re-execing init.""

This reverts commit c450759e8e.

There was nothing wrong with this change originally --- the companion
change in init was broken.

Bug: http://b/19702273
Change-Id: I9d806f6ac251734a61aa90c0741bec7118ea0387

domain.te

@@ -299,7 +299,8 @@ neverallow { domain -init } property_data_file:file no_w_file_perms;
 
 # Only recovery should be doing writes to /system
 neverallow { domain -recovery } { system_file exec_type }:dir_file_class_set
-    { create write setattr relabelfrom relabelto append unlink link rename };
+    { create write setattr relabelfrom append unlink link rename };
+neverallow { domain -recovery -kernel } { system_file exec_type }:dir_file_class_set relabelto;
 
 # Don't allow mounting on top of /system files or directories
 neverallow domain { system_file exec_type }:dir_file_class_set mounton;

file_contexts

@@ -12,7 +12,7 @@
 
 # Executables
 /charger		u:object_r:rootfs:s0
-/init			u:object_r:rootfs:s0
+/init			u:object_r:init_exec:s0
 /sbin(/.*)?		u:object_r:rootfs:s0
 
 # Empty directories

init.te

@@ -1,7 +1,22 @@
-# init switches to init domain (via init.rc).
+# init is its own domain.
 type init, domain, mlstrustedsubject;
 tmpfs_domain(init)
 
+# The init domain is entered by execing init.
+type init_exec, exec_type, file_type;
+
+# /dev/__null__ node created by init.
+allow init tmpfs:chr_file create_file_perms;
+
+#
+# init direct restorecon calls.
+#
+# /dev/socket
+allow init { device socket_device }:dir relabelto;
+# /dev/__properties__
+allow init tmpfs:file relabelfrom;
+allow init properties_device:file relabelto;
+
 # setrlimit
 allow init self:capability sys_resource;
 
@@ -30,6 +45,8 @@ allow init self:capability sys_admin;
 allow init rootfs:dir create_dir_perms;
 allow init rootfs:dir mounton;
 
+allow init proc:dir mounton;
+
 # Mount on /dev/usb-ffs/adb.
 allow init device:dir mounton;
 
@@ -144,8 +161,8 @@ recovery_only(`
   domain_trans(init, rootfs, recovery)
 ')
 domain_trans(init, shell_exec, shell)
-domain_trans(init, rootfs, ueventd)
-domain_trans(init, rootfs, watchdogd)
+domain_trans(init, init_exec, ueventd)
+domain_trans(init, init_exec, watchdogd)
 
 # Support "adb shell stop"
 allow init self:capability kill;
@@ -257,9 +274,9 @@ unix_socket_connect(init, vold, vold)
 
 # The init domain is only entered via setcon from the kernel domain,
 # never via an exec-based transition.
-neverallow { domain -kernel} init:process dyntransition;
-neverallow domain init:process transition;
-neverallow init { file_type fs_type }:file entrypoint;
+neverallow domain init:process dyntransition;
+neverallow { domain -kernel} init:process transition;
+neverallow init { file_type fs_type -init_exec }:file entrypoint;
 
 # Never read/follow symlinks created by shell or untrusted apps.
 neverallow init shell_data_file:lnk_file read;

kernel.te

@@ -3,15 +3,11 @@ type kernel, domain, mlstrustedsubject;
 
 allow kernel self:capability sys_nice;
 
-# Run /init before we have switched domains.
-allow kernel rootfs:file execute_no_trans;
-
-# /dev/__null__ node created by init prior to policy load.
-allow kernel tmpfs:chr_file rw_file_perms;
-
-# setcon to init domain.
-allow kernel self:process setcurrent;
-allow kernel init:process dyntransition;
+# Allow init relabel itself.
+allow kernel rootfs:file relabelfrom;
+allow kernel init_exec:file relabelto;
+# TODO: investigate why we need this.
+allow kernel init:process share;
 
 # cgroup filesystem initialization prior to setting the cgroup root directory label.
 allow kernel unlabeled:dir search;
@@ -20,18 +16,6 @@ allow kernel unlabeled:dir search;
 allow kernel usbfs:filesystem mount;
 allow kernel usbfs:dir search;
 
-# init direct restorecon calls prior to switching to init domain
-# /dev and /dev/socket
-allow kernel tmpfs:dir relabelfrom;
-allow kernel { device socket_device }:dir relabelto;
-# /dev/__properties__
-allow kernel tmpfs:file relabelfrom;
-allow kernel properties_device:file relabelto;
-# /sys
-allow kernel sysfs:{ dir file lnk_file } relabelfrom;
-allow kernel sysfs_type:{ dir file lnk_file } relabelto;
-allow kernel sysfs_type:dir r_dir_perms;
-
 # Initial setenforce by init prior to switching to init domain.
 # We use dontaudit instead of allow to prevent a kernel spawned userspace
 # process from turning off SELinux once enabled.
@@ -58,6 +42,8 @@ allow kernel vold:fd use;
 allow kernel app_data_file:file read;
 allow kernel asec_image_file:file read;
 
+domain_auto_trans(kernel, init_exec, init)
+
 ###
 ### neverallow rules
 ###