tree 301de0927faa32b37e26cfaca256bb4393150f92
parent 2cc6f21833a3c836e369c05497d237de555b4a47
author Tianjie Xu <xunchang@google.com> 1565119925 -0700
committer Tianjie Xu <xunchang@google.com> 1579730506 +0000

Force package installation with FUSE unless the package stores on device

The non-A/B package installation is subject to TOC/TOU flaw if the
attacker can switch the package in the middle of installation. And the
most pratical case is to store the package on an external device, e.g. a
sdcard, and swap the device in the middle.

To prevent that, we can adopt the same protection as used in sideloading
a package with FUSE. Specifically, when we install the package with FUSE,
we read the entire package to cryptographically verify its signature.
The hash for each transfer block is recorded in the memory (TOC), and
the subsequent reads (TOU) will be rejected upon dectecting a mismatch.

This CL forces the package installation with FUSE when the package stays
on a removable media.

Bug: 136498130
Test: Run bin/recovery --update_package with various paths;
and packages are installed from FUSE as expected
Test: recovery_component_test - all passing

Change-Id: Ibc9b095036a2fa624e8edf6c347ed4f12aef072f
Merged-In: Ibc9b095036a2fa624e8edf6c347ed4f12aef072f