Cellrox's Amir Golstein presentation at MobModCon 2015, exploring the Binder under the hood.

1. Amir Goldstein
amir@cellrox.com
www.cellrox.com
copyright Cellrox Inc. 2015
aprilzosia

2. MobModCon 20152
OS Virtualization
Android
applications
Android
framework
Android
applications
Android
framework
Linux
kernel
thinvisor

3. MobModCon 20153
Android OS Virtualization
Android
applications
Android
framework
Android
applications
Android
framework
Linux
kernel
thinvisor
Binder

4. MobModCon 20154
Binder questions
• What is Binder?

5. MobModCon 20155
Binder questions
• What is Binder?
An IPC framework

6. MobModCon 20156
Binder questions
• What is Binder?
An IPC framework
• Why Binder for Android?

7. MobModCon 20157
Binder questions
• What is Binder?
An IPC framework
• Why Binder for Android?
Memory, Graphics, Security, ...

8. MobModCon 20158
Binder questions
• What is Binder?
An IPC framework
• Why Binder for Android?
Memory, Graphics, Security, ...
• Why not?

9. MobModCon 20159
Binder questions
• What is Binder?
An IPC framework
• Why Binder for Android?
Memory, Graphics, Security, ...
• Why not?
Ask LKML

10. MobModCon 201510
Binder questions
• What is Binder?
An IPC framework
• Why Binder for Android?
Memory, Graphics, Security, ...
• Why not?
Ask LKML
• How does it work?

11. MobModCon 201511
Binder questions
• What is Binder?
An IPC framework
• Why Binder for Android?
Memory, Graphics, Security, ...
• Why not?
Ask LKML
• How does it work?
Stay tuned...

12. MobModCon 201512
IPC coloring book
Post Office
BobAlice

13. MobModCon 201513
IPC coloring book - Binder
Public Registry:
➢ Notary
Bob
Alice
I am a Notary
Looking for
a Notary
Notarize
[document]

14. MobModCon 201514
IPC coloring book - Binder
Public Registry:
➢ Notary
Bob
Alice
I am a Notary
Looking for
a Notary
Notarize
[document]
EveI am a translator
Translate
[document]

15. MobModCon 201515
Binder Terminology
❏ AIDL
❏ Binder Client
❏ Proxy
❏ IBinder Interface
❏ Stub
❏ Binder (Object)
❏ Binder Service
❏ Context Manager
❏ Binder Driver
❏ Binder Protocol
❏ Binder Token
❏ Binder Transaction
❏ Parcel
❏ Marshalling
❏ Unmarshalling

16. MobModCon 201516
Binder Code Samples
❏ AIDL
❏ frameworks/base/core/java/android/os/IBatteryPropertiesRegistrar.aidl
❏ Native
❏ frameworks/native/include/batteryservice/IBatteryPropertiesRegistrar.h
❏ frameworks/native/services/batteryservice/IBatteryPropertiesRegistrar.cpp
❏ system/core/healthd/BatteryPropertiesRegistrar.cpp
❏ Java
❏ frameworks/base/services/core/java/com/android/server/BatteryService.java
❏ packages/apps/Battery/src/com/example/cellrox/battery/BatteryActivity.java
BatteryService => BatteryPropertiesRegistrar.registerListener()
BatteryPropertiesRegistrar => BatteryService.BatteryListener.batteryPropertiesChanged() => Intent.
ACTION_BATTERY_CHANGED => BatteryActivity.BroadcastReceiver.onReceive()

17. MobModCon 201517
Binder Debugging
❏ service list, dumpsys
batteryproperties: [android.os.IBatteryPropertiesRegistrar]
❏ /sys/kernel/debug/binder
❏ proc/<pid>
❏ stats (#procs, #threads, #nodes)
❏ transaction_log (call/reply/async)
❏ Quiz: # service >/=/< # proc >/=/< # threads ?

18. MobModCon 201518
Binder Limitation
❏ 1MB per process (TransactionTooLargeException)
❏ Max 15 threads

19. MobModCon 201519
Binder Death
❏ isBinderAlive()
❏ linkToDeath (IBinder.DeathRecipient)

20. MobModCon 201520
Binder Security
❏ enforceCallingOrSelfPermission
❏ getCallingUid()
❏ getCallingPid()
❏ SELinux binder extensions
❏ binder_service
❏ binder_use
❏ binder_call

21. MobModCon 201521
Binder Resources
❏ google.com
❏ elinux.org
❏ lwn.net
❏ androidxref.com
❏ developer.android.com
❏ Android Builders Summit
❏ Deep Dive into Android IPC/Binder Framework

22. MobModCon 201522
Questions?
Thank you!
Amir Goldstein
amir@cellrox.com
www.cellrox.com
copyright Cellrox Inc. 2015