Cannot chmod +x files under /mnt/c/Windows

[dac514]

Version

Microsoft Windows [Version 10.0.22000.708]

WSL Version

• WSL 2
• WSL 1

Kernel Version

Linux version 5.10.16.3-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 Fri Apr 2 22:23:49 UTC 2021

Distro Version

Ubuntu 22.04

Other Software

N/A

Repro Steps

My /etc/wsl.conf is:

[automount]
options = "metadata,umask=022,fmask=111,case=off"

When I run wslsys I get:

/usr/bin/wslsys: line 216: /mnt/c/Windows/System32/reg.exe: Permission denied
/usr/bin/wslsys: line 149: /mnt/c/Windows/System32/chcp.com: Permission denied
/usr/bin/wslsys: line 156: /mnt/c/Windows/System32/WindowsPowerShell/v1.0/powershell.exe: Permission denied
/usr/bin/wslsys: line 149: /mnt/c/Windows/System32/chcp.com: Permission denied
/usr/bin/wslsys: line 279: /mnt/c/Windows/System32/reg.exe: Permission denied
/usr/bin/wslsys: line 265: /mnt/c/Windows/System32/reg.exe: Permission denied
/usr/bin/wslsys: line 216: /mnt/c/Windows/System32/reg.exe: Permission denied
/usr/bin/wslsys: line 274: /mnt/c/Windows/System32/reg.exe: Permission denied
/usr/bin/wslvar: line 149: /mnt/c/Windows/System32/chcp.com: Permission denied
/usr/bin/wslvar: line 156: /mnt/c/Windows/System32/WindowsPowerShell/v1.0/powershell.exe: Permission denied
/usr/bin/wslvar: line 149: /mnt/c/Windows/System32/chcp.com: Permission denied
/usr/bin/wslsys: line 149: /mnt/c/Windows/System32/chcp.com: Permission denied
/usr/bin/wslsys: line 156: /mnt/c/Windows/System32/WindowsPowerShell/v1.0/powershell.exe: Permission denied
/usr/bin/wslsys: line 149: /mnt/c/Windows/System32/chcp.com: Permission denied
/usr/bin/wslsys: line 284: /mnt/c/Windows/System32/reg.exe: Permission denied
/usr/bin/wslsys: line 149: /mnt/c/Windows/System32/chcp.com: Permission denied
/usr/bin/wslsys: line 156: /mnt/c/Windows/System32/WindowsPowerShell/v1.0/powershell.exe: Permission denied
/usr/bin/wslsys: line 149: /mnt/c/Windows/System32/chcp.com: Permission denied
WSL Version: 1
Locale:
Release Install Date: Wed Dec 31 19:00:00 EST 1969
Branch:
Build:
Full Build:
Display Scaling:
Windows Theme: dark
Windows Uptime: 0d 0h 0m
WSL Uptime: 0d 0h 32m
WSL Release: Ubuntu 22.04 LTS
WSL Kernel: Linux 5.10.16.3-microsoft-standard-WSL2
Packages Count: 695

No problem, I think to myself, I'll just run as administrator and do:

 chmod +x  /mnt/c/Windows/System32/reg.exe

Expected Behavior

I can change the exec permission.

Actual Behavior

chmod: changing permissions of '/mnt/c/Windows/System32/reg.exe': Permission denied

Diagnostic Logs

No response

[elsaco]

@connerbw not sure why you'd want to change permissions in C:\Windows\System32 folder, but WSL already mounts C:\ with execute enabled:

tux@RIPPER ~ $ getfacl /mnt/c/Windows/System32/reg.exe
getfacl: Removing leading '/' from absolute path names
# file: mnt/c/Windows/System32/reg.exe
# owner: tux
# group: tux
user::r-x
group::r-x
other::r-x

tux@RIPPER ~ $ ls -l /mnt/c/Windows/System32/reg.exe
-r-xr-xr-x 2 tux tux 77312 Dec  7  2019 /mnt/c/Windows/System32/reg.exe

[dac514]

@elsaco the important part is under the Repro steps please re-read?

 getfacl /mnt/c/Windows/System32/reg.exe
getfacl: Removing leading '/' from absolute path names
# file: mnt/c/Windows/System32/reg.exe
# owner: dac
# group: dac
user::r--
group::r--
other::r--

[dac514]

Why:

• https://gist.github.com/carlolars/7914d2606204001e798c812961c3ac88
• https://kizu514.com/blog/ubuntu-22-04-lts-inside-windows-11/

Similar issues:

• metadata allows us to have correct permissions, but saving a file overrides permissions back to 755 #3165
• Can't open Windows app from WSL 2 anymore #4567

Not sure why this was converted into a "discussion" ... 👎

[sebble]

Remounting the rest of c/Windows has helped me, this restores the unwanted but necessary file permissions within the unmodifiable c/Windows directory.

sudo mount -t drvfs c:/Windows /mnt/c/Windows

[jmelanso]

This fixed the issue for me!

[NotTheDr01ds]

@sebble Good workaround.

@connerbw

Not sure why this was converted into a "discussion" ... 👎

I'm assuming that it was converted into a discussion because it isn't a bug -- It's expected behavior.

WSL runs at the permission level of the Windows user. As such, changing files in C:\Windows (and some other directories) (even the NTFS extended attributes in which WSL stores the Linux permissions) is off-limit to WSL (even sudo/root) when running under your normal account. The behavior is noted in the gist you linked to. While it recommends running WSL as Administrator, I would caution against that.

Much better and safer to use @sebble's workaround.