init: Add an selinux transition for snapuserd.
With compressed VAB updates, it is not possible to mount /system without
first running snapuserd, which is the userspace component to the dm-user
kernel module. This poses a problem because as soon as selinux
enforcement is enabled, snapuserd (running in a kernel context) does not
have access to read and decompress the underlying system partition.
To account for this, we split SelinuxInitialize into multiple steps:
First, sepolicy is read into an in-memory string.
Second, the device-mapper tables for all snapshots are rebuilt. This
flushes any pending reads and creates new dm-user devices. The original
kernel-privileged snapuserd is then killed.
Third, sepolicy is loaded from the in-memory string.
Fourth, we re-launch snapuserd and connect it to the newly created
dm-user devices. As part of this step we restorecon device-mapper
devices and /dev/block/by-name/super, since the new snapuserd is in a
limited context.
Finally, we set enforcing mode.
This sequence ensures that snapuserd has appropriate privileges with a
minimal number of permissive audits.
Bug: 173476209
Test: full OTA with VABC applies and boots
Change-Id: Ie4e0f5166b01c31a6f337afc26fc58b96217604e
diff --git a/init/Android.mk b/init/Android.mk
index c881e2f..561d641 100644
--- a/init/Android.mk
+++ b/init/Android.mk
@@ -57,6 +57,8 @@
reboot_utils.cpp \
selabel.cpp \
selinux.cpp \
+ service_utils.cpp \
+ snapuserd_transition.cpp \
switch_root.cpp \
uevent_listener.cpp \
util.cpp \