[WSL2][systemd][interop] Unable to Execute Windows Binary when systemd enabled

[thelastlin]

Version

0.67.6.0

WSL Version

• WSL 2
• WSL 1

Kernel Version

Linux version 5.15.62.1-microsoft-standard-WSL2 (oe-user@oe-host) (x86_64-msft-linux-gcc (GCC) 9.3.0, GNU ld (GNU Binutils) 2.34.0.20200220) #1 SMP Wed Aug 24 22:24:20 UTC 2022

Distro Version

Ubuntu 22.04

Other Software

No response

Repro Steps

1. Edit /etc/wsl.conf, enable systemd support. (https://devblogs.microsoft.com/commandline/systemd-support-is-now-available-in-wsl/)
2. Run wsl.exe --shutdown in wsl2 shell, and reopen the shell.
3. Run wsl.exe --version or some other PE binaries, and shell will warn you that the "exec format error" or "MZ: not found"

Expected Behavior

Able to execute any valid PE binaries.

Actual Behavior

"exec format error" or "MZ: not found"

Diagnostic Logs

$ execve("/mnt/c/WINDOWS/system32/calc.exe", ["calc.exe"], 0x7ffc12cdd038 /* 37 vars */) = -1 ENOEXEC (Exec format error)
strace: exec: Exec format error
+++ exited with 1 +++

$ echo $WSL_INTEROP
/run/WSL/410_interop

$ ll /run/WSL
total 0
drwxrwxrwx  2 root root 100  9月 22 12:29 ./
drwxr-xr-x 26 root root 760  9月 22 12:29 ../
srwxrwxrwx  1 root root   0  9月 22 12:29 2_interop=
srwxrwxrwx  1 root root   0  9月 22 12:29 410_interop=
srwxrwxrwx  1 root root   0  9月 22 12:29 549_interop=

$ ll /proc/sys/fs/binfmt_misc/
total 0
drwxr-xr-x 2 root root 0  9月 22 12:29 ./
dr-xr-xr-x 1 root root 0  9月 22 12:29 ../
-rw-r--r-- 1 root root 0  9月 22 12:29 llvm-12-runtime.binfmt
-rw-r--r-- 1 root root 0  9月 22 12:29 llvm-14-runtime.binfmt
-rw-r--r-- 1 root root 0  9月 22 12:29 python2.7
-rw-r--r-- 1 root root 0  9月 22 12:29 python3.10
--w------- 1 root root 0  9月 22 12:29 register
-rw-r--r-- 1 root root 0  9月 22 12:29 status

$cat /proc/sys/fs/binfmt_misc/WSLInterop
cat: /proc/sys/fs/binfmt_misc/WSLInterop: No such file or directory

[WitherZuo]

The interoperability of WSL and Windows relies on WSL init. After systemd is turned on, WSL init will also run under systemd, which may be one of the reasons for breaking the interoperability function.

[Re4son]

I don't think it is by design @WitherZuo. I have both systemd and interop working temporarily in Ubuntu but it stops working when I start another WSL distro.
Once I shutdown WSL and start Ubuntu on its own it works again.

[reynoldskr]

The binfmt_misc handler for WSL2 to run Windows binaries either is getting overwritten by systemd or is never set:

systemd enabled

adam@ADAM-HOMEDESK /p/s/f/binfmt_misc> ls -lah
total 0
drwxr-xr-x 2 root root 0 Sep 22 12:20 ./
dr-xr-xr-x 1 root root 0 Sep 22 12:20 ../
-rw-r--r-- 1 root root 0 Sep 22 12:20 llvm-13-runtime.binfmt
-rw-r--r-- 1 root root 0 Sep 22 12:20 llvm-14-runtime.binfmt
-rw-r--r-- 1 root root 0 Sep 22 12:20 python3.10
--w------- 1 root root 0 Sep 22 12:20 register
-rw-r--r-- 1 root root 0 Sep 22 12:20 status

systemd disabled

adam@ADAM-HOMEDESK /p/s/f/binfmt_misc> ls -lah
total 0
drwxr-xr-x 2 root root 0 Sep 22 12:21 ./
dr-xr-xr-x 1 root root 0 Sep 22 12:21 ../
--w------- 1 root root 0 Sep 22 12:21 register
-rw-r--r-- 1 root root 0 Sep 22 12:21 status
-rw-r--r-- 1 root root 0 Sep 22 12:21 WSLInterop

[cerebrate]

Systemd does that, as those of us who've futzed with alternative systemd solutions in the past have come to know. The solution-slash-workaround is to put this file:

https://github.com/arkane-systems/bottle-imp/blob/master/othersrc/usr-lib/binfmt.d/WSLInterop.conf

in your /usr/lib/binfmt.d .

[Re4son]

Good pointer @cerebrate, thanks heaps! That helped.

I compared the distro that worked out of the box and the distro that didn't and the difference was existing config files in "/usr/lib/binfmt.d"

• Stock Ubuntu out of the box with nothing in "/usr/lib/binfmt.d" works fine
• Kali Linux with plenty of packages installed and thus several config files in "/usr/lib/binfmt.d" does not work

Ubuntu on its own works fine.
Kali doesn't work and also breaks Ubuntu.
Deleting everything under "/usr/lib/binfmt.d" in the Kali distro fixes Kali (and stops breaking Ubuntu).
Adding your file to "/usr/lib/binfmt.d" alongside the existing files fixes Kali (and stops breaking Ubuntu).

Thanks for that @cerebrate, much appreciate it.

[benhillis]

@Re4son - thanks for the additional detail. This boils down to Linux not supporting namespacing of binfmt_misc interpreters. Any fix we make is going to be problematic until that is resolved.

It looks like we need to handle the case where the distro has binfmt interpreters installed by adding our own .conf file though.

[dbbao]

有什么解决方案吗，我也碰到这个问题了

[PhyX-Meow]

Systemd does that, as those of us who've futzed with alternative systemd solutions in the past have come to know. The solution-slash-workaround is to put this file:

https://github.com/arkane-systems/bottle-imp/blob/master/othersrc/usr-lib/binfmt.d/WSLInterop.conf

in your /usr/lib/binfmt.d .

@lhrbest 这里已经给了 workaround 了

[dbbao]

我是Ubuntu 20.04，会报如下的错误：
``root@lhrxxt:/mnt/f/pwsh# cmd.exe
<3>WSL (996) ERROR: UtilConnectUnix:511: connect failed 2
root@lhrxxt:/mnt/f/pwsh#
root@lhrxxt:/mnt/f/pwsh# ll /usr/lib/binfmt.d/
total 12
drwxr-xr-x 2 root root 4096 Sep 26 15:30 ./
drwxr-xr-x 122 root root 4096 Sep 14 10:57 ../
-rw-r--r-- 1 root root 27 Sep 26 15:30 WSLInterop.conf
root@lhrxxt:/mnt/f/pwsh# cmd.exe
<3>WSL (1000) ERROR: UtilConnectUnix:511: connect failed 2
root@lhrxxt:/mnt/f/pwsh#
root@lhrxxt:/mnt/f/pwsh#

[PhyX-Meow]

@lhrbest Try restart wsl. Normally there should be a file named WSLInterop.

[kpko]

Hi,

I'm using https://github.com/yuk7/ArchWSL and enabling systemd reliably broke the ability to execute Windows applications from WSL. I resolved the issue by generating a file in /usr/lib/binfmt.d/WSLInterop.conf with the following content:

:WSLInterop:M::MZ::/init:PF

Also I removed mono.conf from the same directory as they might create a conflicting mapping. After running sudo systemctl restart systemd-binfmt, my executables are working now.

I've tried several binfmt entries but most of the entries I found online did not include the 'PF' flags and resulted in an error.