subcontext_test had been failing due to setexeccon() failing to
transition to vendor_init context. This is a good thing as nothing
other than init should be able to transition into this context.
I don't want to add code to skip the setexeccon() call only for the
tests, so I instead call setexeccon() with the return value of
getcon(). This works however only for root, so these tests are
skipped for non-root.
Test: init unit tests
Change-Id: I8a415599e0ec5506511202f7f5018c0e5265837d
One of the major aspects of treble is the compartmentalization of system
and vendor components, however init leaves a huge gap here, as vendor
init scripts run in the same context as system init scripts and thus can
access and modify the same properties, files, etc as the system can.
This change is meant to close that gap. It forks a separate 'subcontext'
init that runs in a different SELinux context with permissions that match
what vendors should have access to. Commands get sent over a socket to
this 'subcontext' init that then runs them in this SELinux context and
returns the result.
Note that not all commands run in the subcontext; some commands such as
those dealing with services only make sense in the context of the main
init process.
Bug: 62875318
Test: init unit tests, boot bullhead, boot sailfish
Change-Id: Idf4a4ebf98842d27b8627f901f961ab9eb412aee
