The initial launch of snapuserd happens in first-stage init, before
sepolicy is loaded, since snapuserd is needed to mount initial
partitions. After sepolicy is loaded, we immediately re-launch snapuserd
in the correct context. This requires a transition similar to init.
The "allow" lines for the kernel happen in permissive mode, since we
need to relabel critical parts of /dev/block in order to re-launch
snapuserd.
Bug: 173476209
Test: OTA applies with ro.virtual_ab.compression.enabled = true
Change-Id: I80184e737ccb558107a14b384a61f7fec31c9428
Restrict access to controlling snapuserd via ctl properties. Allow
update_engine to control snapuserd, and connect/write to its socket.
update_engine needs this access so it can create the appropriate dm-user
device (which sends queries to snapuserd), which is then used to build
the update snapshot.
This also fixes a bug where /dev/dm-user was not properly labelled. As a
result, snapuserd and update_engine have been granted r_dir_perms to
dm_user_device.
Bug: 168554689
Test: full ota with VABC enabled
Change-Id: I1f65ba9f16a83fe3e8ed41a594421939a256aec0
dm-user is a new device-mapper module, providing a FUSE-like service for
block devices. It creates control nodes as misc devices under
/dev/dm-user/. Make sure these nodes get a unique selabel.
snapuserd is a daemon for servicing requests from dm-user. It is a
low-level component of Virtual A/B updates, and provides the bridge
betewen dm-snapshot and the new COW format. For this reason it needs
read/write access to device-mapper devices.
Bug: 168259959
Test: ctl.start snapuserd, no denials
vts_libsnapshot_test, no denials
Change-Id: I36858a23941767f6127d6fbb9e6755c68b91ad31
