1. A Sneak Peek Into
Android Internals
GDG Dec-2012
By Yoav Weiss
MobileSpaces Founder & CTO

2. What we're going to talk about
● Virtualizing Android
● Understanding Android internals
through dynamic tracing

3. What is MobileSpaces
● Solving BYOD through a unique
virtualization platform
● Any app, any device, no root(!)
● Funded by Accel Partners

4. Short demo of

5. Android Security Model in a nutshell
● The Android security model is based on linux
kernel separation
● Apps and services run in usermode
● Each app is assigned a unique uid and a
home directory
● Android takes advantage of linux gids
● Android permissions are enforced by uid
rather than package

6. Application Initialization Process
Step 1 - ActivityManager asks the System Server to start
Activity/Service/Receiver/Provider
* ActivityManager is actually a service running in the system_server process

7. Application Initialization Process
Step 2 - System Server checks which package provides that functionality

8. Application Initialization Process
Step 3 - System Server tells Zygote to load the package

9. Application Initialization Process
Step 4 - Zygote forks and creates the new application process

10. Application Initialization Process
Step 5 - The application is set up:
● Check permissions
● Set gid
● Set uid
● Load the package

11. Application Initialization Process
Step 6 - The application starts listening for instructions from
ActivityManager (Activity lifecycle messages)

12. Virtualizing Android
Since Android apps and services run in
usermode, they must interact with the world via
syscalls.

13. Binder Flow Example
Step 1 - Camera app asks MediaServer to access the camera

14. Binder Flow Example
Step 2 - MediaServer asks system_server if camera app is allow to access
the camera

15. Binder Flow Example
Step 3 - system_server grants the permission

16. Binder Flow Example
Step 4 - MediaServer opens the camera driver and configures it

17. Binder Flow Example
Step 5 - MediaServer returns the file descriptor to the camera app which
can now use the camera

18. Live Demos Using the
platform

19. Summary
● We virtualized Android. No root required
● We used the VM to peek into the system
MobileSpaces is hiring!
Visit us at: http://www.mobilespaces.som
Contact us: jobs@mobilespaces.com

20. Q&A