Implement a new method of sideloading over ADB that does not require
the entire package to be held in RAM (useful for low-RAM devices and
devices using block OTA where we'd rather have more RAM available for
binary patching).
We communicate with the host using a new adb service called
"sideload-host", which makes the host act as a server, sending us
different parts of the package file on request.
We create a FUSE filesystem that creates a virtual file
"/sideload/package.zip" that is backed by the ADB connection -- users
see a normal file, but when they read from the file we're actually
fetching the data from the adb host. This file is then passed to the
verification and installation systems like any other.
To prevent a malicious adb host implementation from serving different
data to the verification and installation phases of sideloading, the
FUSE filesystem verifies that the contents of the file don't change
between reads -- every time we fetch a block from the host we compare
its hash to the previous hash for that block (if it was read before)
and cause the read to fail if it changes.
One necessary change is that the minadbd started by recovery in
sideload mode no longer drops its root privileges (they're needed to
mount the FUSE filesystem). We rely on SELinux enforcement to
restrict the set of things that can be accessed.
Change-Id: Ida7dbd3b04c1d4e27a2779d88c1da0c7c81fb114
In kernel(3.10) USB ADB gadget driver is removed.
Using Functionfs for USB adb gadget.
Android recovery uses a stripped down version
of adb command for sideload only. It's missing
the ffs function support, so add the ffs
support to allow sideload command to work
b/12608946
Change-Id: I4ad024723dfc5bdb544548391f99637c390b171e
Signed-off-by: Pierre Couillaud <pierre@broadcom.com>
Make minadbd drop its root privileges after initializing. We need to
make the /tmp directory writable by the shell group so that it can
drop the sideloaded file there.
Change-Id: I67b292cf769383f0f67fb934e5a80d408a4c131d
Rather than depending on the existence of some place to store a file
that is accessible to users on an an unbootable device (eg, a physical
sdcard, external USB drive, etc.), add support for sideloading
packages sent to the device with adb.
This change adds a "minimal adbd" which supports nothing but receiving
a package over adb (with the "adb sideload" command) and storing it to
a fixed filename in the /tmp ramdisk, from where it can be verified
and sideloaded in the usual way. This should be leave available even
on locked user-build devices.
The user can select "apply package from ADB" from the recovery menu,
which starts minimal-adb mode (shutting down any real adbd that may be
running). Once minimal-adb has received a package it exits
(restarting real adbd if appropriate) and then verification and
installation of the received package proceeds.
Change-Id: I6fe13161ca064a98d06fa32104e1f432826582f5
