Now that we're treating storage as a runtime permission, we need to
grant read/write access without killing the app. This is really
tricky, since we had been using GIDs for access control, and they're
set in stone once Zygote drops privileges.
The only thing left that can change dynamically is the filesystem
itself, so let's do that. This means changing the FUSE daemon to
present itself as three different views:
/mnt/runtime_default/foo - view for apps with no access
/mnt/runtime_read/foo - view for apps with read access
/mnt/runtime_write/foo - view for apps with write access
There is still a single location for all the backing files, and
filesystem permissions are derived the same way for each view, but
the file modes are masked off differently for each mountpoint.
During Zygote fork, it wires up the appropriate storage access into
an isolated mount namespace based on the current app permissions. When
the app is granted permissions dynamically at runtime, the system
asks vold to jump into the existing mount namespace and bind mount
the newly granted access model into place.
Bug: 21858077
Change-Id: Iade538e4bc7af979fe20095f74416e8a0f165a4a
When a private volume is mounted, create an emulated volume above it
hosted at the /media path on that device. That emulated volume is
automatically torn down when unmounting the private volume.
Add "removed" state for volume, which signals to framework that
media has left the building, send when the volume is destroyed.
Bug: 19993667
Change-Id: I1f82b51de578ac5cfcc5d7b9a6fb44f6f25c775c
Wire up new Disk and VolumeBase objects and events to start replacing
older DirectVolume code. Use filesystem UUID as visible PublicVolume
name to be more deterministic.
When starting, create DiskSource instances based on fstab, and watch
for kernel devices to appear. Turn matching devices into Disk
objects, scan for partitions, and create any relevant VolumeBase
objects. Broadcast all of these events towards userspace so the
framework can decide what to mount.
Keep track of the primary VolumeBase, and update the new per-user
/storage/self/primary symlink for all started users.
Provide a reset command that framework uses to start from a known
state when runtime is restarted. When vold is unexpectedly killed,
try recovering by unmounting everything under /mnt and /storage
before moving forward.
Remove UMS sharing support for now, since no current devices support
it; MTP is the recommended solution going forward because it offers
better multi-user support.
Switch killProcessesWithOpenFiles() to directly take signal. Fix
one SOCK_CLOEXEC bug, but SELinux says there are more lurking.
Bug: 19993667
Change-Id: I2dad1303aa4667ec14c52f774e2a28b3c1c1ff6d
This is the first in a series of changes that are designed to
introduce better support for dynamic block devices.
It starts by defining a new Volume object which represents a storage
endpoint that knows how to mount, unmount, and format itself. This
could be a filesystem directly on a partition, or it could be an
emulated FUSE filesystem, an ASEC, or an OBB.
These new volumes can be "stacked" so that unmounting a volume will
also unmount any volumes stacked above it. Volumes that provide
shared storage can also be asked to present themselves (through bind
mounts) into user-specific mount areas.
This change also adds a Disk class which is created based on block
kernel netlink events. Instead of waiting for partition events from
the kernel, it uses gptfdisk to read partition details and creates
the relevant Volume objects.
Change-Id: I0e8bc1f8f9dcb24405f5e795c0658998e22ae2f7
