QuarksLab has a new blog on encryption support of Linux’s Ext4 file system:
Excerpting the beginning of the post:
Linux 4.1 has arrived with a new feature for its popular ext4 filesystem: filesystem-level encryption! This feature appears to have been implemented by Google since they plan to use it for future versions of Android and Chrome OS. Android filesystem encryption currently relies on dm-crypt. Google’s motivations for pushing encryption to ext4 seem:
* To avoid using a stacked filesystem design (for better performance?).
* To encrypt data with integrity.
* To allow multiple users to encrypt their files with different keys on the same filesystem.
More Information:
http://blog.quarkslab.com/a-glimpse-of-ext4-filesystem-level-encryption.html
Also see this article from April:
https://lwn.net/Articles/639427/
UPDATE: See-also this recent talk from Google at the 2015 Linux Security Summit:
Encrypting Android Devices
Paul Lawrence and Mike Halcrow, Google
Firmware Security 