can't cat /proc/sys/fs/binfmt_misc/WSLInterop Too many levels of symbolic links

[QAston]

While in the environment cat /proc/sys/fs/binfmt_misc/WSLInterop produces this error

Too many levels of symbolic links

This breaks wslu

[QAston]

Looks like this was solved in another project by disabling some systemd services and explictly mounting binfmt_misc: https://github.com/DamionGans/ubuntu-wsl2-systemd-script/issues/15 https://github.com/DamionGans/ubuntu-wsl2-systemd-script/pull/17/files

It'd be great to have these changes ported here, as disabling the service alone doesn't fix the issue.

[QAston]

I resolved the issue locally by mounting binfmt:

diff --git a/src/bottle.rs b/src/bottle.rs
index f04804a..cbb4768 100644
--- a/src/bottle.rs
+++ b/src/bottle.rs
@@ -243,6 +243,14 @@ fn exec_systemd2_child(systemd_bin: CString) -> Result<(), error::Error> {
     )
     .expect("proc mount failure");

+    nix::mount::mount(
+        Some(OsStr::new("binfmt_misc")),
+        OsStr::new("/proc/sys/fs/binfmt_misc"),
+        Some(OsStr::new("binfmt_misc")),
+        MsFlags::MS_NOSUID | MsFlags::MS_NODEV | MsFlags::MS_NOEXEC,
+        OS_NONE,
+    )
+    .expect("binfmt mount failure");
     nix::unistd::chdir("/").unwrap();
     nix::unistd::setgid(nix::unistd::Gid::from_raw(0)).unwrap();
     nix::unistd::setuid(nix::unistd::Uid::from_raw(0)).unwrap();

and disabling binfmt mount related services

sudo mkdir -p /etc/systemd/wsl2-incompatible/user/sockets.target.wants/ /lib/systemd/wsl2-incompatible/system/sysinit.target.wants/ /usr/lib/systemd/wsl2-incompatible/system/
# remove binfmt mounting done by systemd because it doesn't work and triggers 'too many simlinks error
sudo mv /lib/systemd/system/sysinit.target.wants/proc-sys-fs-binfmt_misc.automount /lib/systemd/wsl2-incompatible/system/sysinit.target.wants/
sudo mv /lib/systemd/system/sysinit.target.wants/systemd-binfmt.service /lib/systemd/wsl2-incompatible/system/sysinit.target.wants/
sudo mv /usr/lib/systemd/system/proc-sys-fs-binfmt_misc.automount /usr/lib/systemd/wsl2-incompatible/system/
sudo mv /usr/lib/systemd/system/proc-sys-fs-binfmt_misc.mount /usr/lib/systemd/wsl2-incompatible/system/