When termux uses the system signature, an error is reported when the command is executed

[tangzeyu7]

can't execute: Permission denied

Configuration

• Termux uses the system signature in the platform source code
  

• Configure sharedUserId="android.uid.system" in AndroidManifest
  

Phenomenon

Session mode

• Start interface

  

• Execute Command

  

Failsafe mode

• The start interface is consistent with the Session

• Execute Command

  

• ls -l

  
  
  

• Execute Command: ./

  

What causes this problem? How to solve it?

[agnostic-apollo]

Are you on android 10+? If yes, then likely issue considering that now termux will be running as the user of the system package, its targetSdkVersion restrictions would apply and not termux's own. That's why /system/bin binaries work fine but not the ones in termux's own priv app data dir under $PREFIX. Check https://github.com/termux/termux-packages/wiki/Termux-and-Android-10

Check logcat for confirmation, likely selinux avc denial entries.

I wonder why sh session started in normal session instead of bash (failing), maybe canExecute() failed (unless OP changed default). 🤔

[tangzeyu7]

Are you on android 10+? If yes, then likely issue considering that now termux will be running as the user of the system package, its targetSdkVersion restrictions would apply and not termux's own. That's why /system/bin binaries work fine but not the ones in termux's own priv app data dir under $PREFIX. Check https://github.com/termux/termux-packages/wiki/Termux-and-Android-10

Check logcat for confirmation, likely selinux avc denial entries.

I wonder why sh session started in normal session instead of bash (failing), maybe canExecute() failed (unless OP changed default). 🤔

You're right, it does run on Android 10.
Error log:

2021-07-27 09:44:47.910 18506-18506/com.termux W/com.termux: type=1400 audit(0.0:1245): avc: denied { execute } for name="login" dev="dm-8" ino=644006 scontext=u:r:system_app:s0 tcontext=u:object_r:system_app_data_file:s0 tclass=file permissive=0
2021-07-27 09:45:00.002 18594-18594/? W/sh: type=1400 audit(0.0:1277): avc: denied { execute } for name="coreutils" dev="dm-8" ino=646644 scontext=u:r:system_app:s0 tcontext=u:object_r:system_app_data_file:s0 tclass=file permissive=0

This problem has been bothering me for 2 days, thank you for your help!

[agnostic-apollo]

You are welcome.

[TREYWANGCQU]

Thanks

[agnostic-apollo]

@tangzeyu7 You may wanna check out #2445 (comment).

[tangzeyu7]

@tangzeyu7 You may wanna check out #2445 (comment).

OK, thank you for reminding me.

[agnostic-apollo]

Welcome.