Disabling interop via /proc/sys/fs/binfmt_misc/WSLInterop does not work

[debuglevel]

Windows Version

Microsoft Windows [Version 10.0.19045.4291]

WSL Version

2.1.5.0

Are you using WSL 1 or WSL 2?

• WSL 2
• WSL 1

Kernel Version

5.15.146.1-2

Distro Version

Ubuntu 22.04

Other Software

No response

Repro Steps

1. echo 0 | sudo tee /proc/sys/fs/binfmt_misc/WSLInterop
2. cat /proc/sys/fs/binfmt_misc/WSLInterop to ensure it is disabled.
3. python3.exe --version

Expected Behavior

Should not work.

Actual Behavior

Works.

Diagnostic Logs

No response

[debuglevel]

The way described in #8932 works however.

[github-actions]

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If this a feature request, please reply with '/feature'. If this is a question, reply with '/question'.
Otherwise please attach logs by following the instructions below, your issue will not be reviewed unless they are added. These logs will help us understand what is going on in your machine.

How to collect WSL logs

Download and execute collect-wsl-logs.ps1 in an administrative powershell prompt:

Invoke-WebRequest -UseBasicParsing "https://raw.githubusercontent.com/microsoft/WSL/master/diagnostics/collect-wsl-logs.ps1" -OutFile collect-wsl-logs.ps1
Set-ExecutionPolicy Bypass -Scope Process -Force
.\collect-wsl-logs.ps1

The scipt will output the path of the log file once done.

Once completed please upload the output files to this Github issue.

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View similar issues

Please view the issues below to see if they solve your problem, and if the issue describes your problem please consider closing this one and thumbs upping the other issue to help us prioritize it!

Closed similar issues:

• Cannot disable Interop via /etc/wsl.conf -- 0.68.2 regression (probably introduced in 0.67.6) (#8932), similarity score: 0.75

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[firejox]

Check the files in /proc/sys/fs/binfmt_misc/ and make sure none of them is similar to /proc/sys/fs/binfmt_misc/WSLInterop.

[zcobol]

@debuglevel there are two WSLInterop files in /proc/sys/fs/binfmt_misc. Disable in WSLInterop and WSLInterop-late

root@eleven:~# echo 0 | tee /proc/sys/fs/binfmt_misc/WSLInterop
0
root@eleven:~# cat /proc/sys/fs/binfmt_misc/WSLInterop
disabled
interpreter /init
flags: PF
offset 0
magic 4d5a
root@eleven:~# python3.exe --version
Python 3.12.3
root@eleven:~# echo 0 | tee /proc/sys/fs/binfmt_misc/WSLInterop-late
0
root@eleven:~# cat /proc/sys/fs/binfmt_misc/WSLInterop-late
disabled
interpreter /init
flags: P
offset 0
magic 4d5a
root@eleven:~# python3.exe --version
/mnt/c/Users/valli/AppData/Local/Microsoft/WindowsApps/python3.exe: line 1: MZ: command not found

[OneBlue]

zcobol's answer is correct. When systemd is enabled, WSL creates two binfmt_misc entries. The supported way of disabling interop is via wsl.conf though:

[interop]
enabled=false