SerialChat avc permission error on Android

[Sathya]

Hi,

I am trying to use SerialChat application located at frameworks/base/tests/SerialChat for accessing serial port (/dev/ttyHSL1) from Android Java application layer. But when I launch application, it throws exception related to permission. I have verified whether the serial_service is included in the selinux policy.

I have verified in the service_context at out directory of android build.

serial                                    u:object_r:serial_service:s0

In file_contexts at out directory of android build.

/dev/ttyHSL1                                    u:object_r:serial_device:s0

In /obj/ETC/sepolicy_intermediates/policy.conf at out directory of android build.

type serial_device, dev_type;
type serial_service, system_api_service, system_server_service, service_manager_type;
allow system_app serial_service: service_manager find;
allow system_server serial_device:chr_file { { getattr open read ioctl lock } { open append write } };
allow untrusted_app serial_service: service_manager find;

Logcat when I keep SELinux in enforce mode, following is the log.

01-01 00:03:15.509   799   972 I ActivityManager: START u0 {act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 pkg=com.android.serialchat cmp=com.android.serialchat/.SerialChat} from uid 10011 on display 0
01-01 00:03:15.570   799  1346 I ActivityManager: Start proc 1960:com.android.serialchat/u0a54 for activity com.android.serialchat/.SerialChat
[  193.544684] type=1400 audit(195.699:301): avc: denied { read write } for pid=1308 comm="Binder_5" path="/dev/ttyHSL1" dev="tmpfs" ino=8663 scontext=u:r:untrusted_app:s0:c512,c768 tcontext=u:object_r:serial_device:s0 tclass=chr_file permissive=0 xb853c5f8
01-01 00:03:15.649  1960  1960 W System  : ClassLoader referenced unknown path: /data/app/com.android.serialchat-1/lib/arm
01-01 00:03:15.709  1960  1960 E SerialManager: SerialManager.openSerialPort name is /dev/ttyHSL1 speed is 115200
01-01 00:03:15.717  1960  1960 E JavaBinder: !!! FAILED BINDER TRANSACTION !!!  (parcel size = 104)
01-01 00:03:15.719  1960  1960 E SerialManager: exception in SerialManager.openSerialPort
01-01 00:03:15.719  1960  1960 E SerialManager: android.os.DeadObjectException: Transaction failed on small parcel; remote process probably died
01-01 00:03:15.719  1960  1960 E SerialManager:         at android.os.BinderProxy.transactNative(Native Method)
01-01 00:03:15.719  1960  1960 E SerialManager:         at android.os.BinderProxy.transact(Binder.java:503)
01-01 00:03:15.719  1960  1960 E SerialManager:         at android.hardware.ISerialManager$Stub$Proxy.openSerialPort(ISerialManager.java:115)
01-01 00:03:15.719  1960  1960 E SerialManager:         at android.hardware.SerialManager.openSerialPort(SerialManager.java:69)
01-01 00:03:15.719  1960  1960 E SerialManager:         at com.android.serialchat.SerialChat.onResume(SerialChat.java:81)
01-01 00:03:15.719  1960  1960 E SerialManager:         at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1259)
01-01 00:03:15.719  1960  1960 E SerialManager:         at android.app.Activity.performResume(Activity.java:6361)
01-01 00:03:15.719  1960  1960 E SerialManager:         at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3092)
01-01 00:03:15.719  1960  1960 E SerialManager:         at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:3134)
01-01 00:03:15.719  1960  1960 E SerialManager:         at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2481)
01-01 00:03:15.719  1960  1960 E SerialManager:         at android.app.ActivityThread.access$900(ActivityThread.java:150)
01-01 00:03:15.719  1960  1960 E SerialManager:         at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
01-01 00:03:15.719  1960  1960 E SerialManager:         at android.os.Handler.dispatchMessage(Handler.java:102)
01-01 00:03:15.719  1960  1960 E SerialManager:         at android.os.Looper.loop(Looper.java:148)
01-01 00:03:15.719  1960  1960 E SerialManager:         at android.app.ActivityThread.main(ActivityThread.java:5417)
01-01 00:03:15.719  1960  1960 E SerialManager:         at java.lang.reflect.Method.invoke(Native Method)
01-01 00:03:15.719  1960  1960 E SerialManager:         at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
01-01 00:03:15.719  1960  1960 E SerialManager:         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
01-01 00:03:15.727  1960  1973 D OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true
01-01 00:03:18.833  1308  1308 W Binder_5: type=1400 audit(0.0:301): avc: denied { read write } for path="/dev/ttyHSL1" dev="tmpfs" ino=8663 scontext=u:r:untrusted_app:s0:c512,c768 tcontext=u:object_r:serial_device:s0 tclass=chr_file permissive=0
01-01 00:03:16.005   799   843 I ActivityManager: Displayed com.android.serialchat/.SerialChat: +452ms


Logcat when I keep SELinux in permissive mode using setenforce 0, following is the log.

01-01 00:03:37.582   799  1346 I ActivityManager: START u0 {act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.android.serialchat/.SerialChat (has extras)} from uid 10016 on display 0
01-01 00:03:37.668  1960  1960 E SerialManager: SerialManager.openSerialPort name is /dev/ttyHSL1 speed is 115200
01-01 00:03:40.793   985   985 I Binder_4: type=1400 audit(0.0:303): avc: denied { read write } for path="/dev/ttyHSL1" dev="tmpfs" ino=8663 scontext=u:r:untrusted_app:s0:c512,c768 tcontext=u:object_r:serial_device:s0 tclass=chr_file permissive=1
01-01 00:03:40.793  1960  1960 I roid.serialchat: type=1400 audit(0.0:304): avc: denied { ioctl } for path="/dev/ttyHSL1" dev="tmpfs" ino=8663 ioctlcmd=5401 scontext=u:r:untrusted_app:s0:c512,c768 tcontext=u:object_r:serial_device:s0 tclass=chr_file permissive=1
01-01 00:03:37.671  1960  1960 E SerialManager: SerialManager.openSerialPort pfd is not null
01-01 00:03:37.675  1960  2028 D SerialChat: run
01-01 00:03:37.675  1960  2028 D SerialChat: calling read
01-01 00:03:37.754   799   843 I ActivityManager: Displayed com.android.serialchat/.SerialChat: +134ms

Apart from those sepolicy, is there anything else to be added? Or do I miss anything else?

Regards,
Sathya

[David Escalona]

Hello,

I am having exactly the same issue but with an SPI interface. I think I have set all the SE Policy permissions and rules correctly, but I keep getting the denied message followed by the binder transaction failed crash.

Were you able to fix this issue? If so, what was the correct fix?

Thanks in advance!