tree 8b6968fe9d0c0fbf5bf2713671917eea7022cb27
parent 4a35ef0a53d1f8041adc8bf49585e700bb7af803
author Greg Kaiser <gkaiser@google.com> 1518229499 -0800
committer Greg Kaiser <gkaiser@google.com> 1518455236 -0800

cryptfs: Optionally get crypt type from properties

Instead of hardcoding to "aes-cbc-essiv:sha256", we introduce a
new property, "ro.crypto.crypt_type_name", to allow the use of
different crypt methods.  The only other method we currently
support is "speck128-xts-plain64", although new methods are
easily added.

We intentionally derive things like the keysize from the given
crypt name, to reduce exploit vectors.  We also only accept
crypt names the code has whitelisted.

The biggest impact is replacing the hard-coded KEY_LEN_BYTES.
For compile-time buffers, we use the MAX_KEY_LEN to assure they
will be big enough for any crypt type.  For run-time sizing,
we use the value derived from our property.

Bug: 73079191
Test: On an encrypted gobo, booted successfully with (1) no property set, (2) proproperty set to invalid value (and confirmed we defaulted to aes), and (3) after wiping userdata, with property set to "speck128-xts-plain64", confirmed we were using SPECK.
Change-Id: Ic4e10840d6ee2a4d4df58582448e0f768e6f403f