Share private SSH keys with Bash on Windows

Question

I have Windows 10 with Git installed. This Git uses my C:/Users/MyName dir as the HOME directory and the /.ssh/ dir within, appropriately for sourcing my private SSH keys.

I have just enabled and setup "Bash on Ubuntu on Windows" (what a mouthful!) and installed Git therein also. I would like both Gits to use the same set of keys such that it does not matter what environment I work in on this machine, my commits will always come from me.

Trouble being that the HOME dir in bash is different (/home/MyName) and thus it does not see the keys located in the now distant ../../mnt/c/Users/MyName/.ssh. I thought I'd be on to a winner by changing the HOME environment variable using

export HOME=/c/mnt/Users/MyName

This did change the HOME dir successfully but the bash git still does not see the keys contained within the ./.ssh dir.

I'm not sure if this is A) because bash git expects keys in a different file format? (current ones are id_rsa and id_rsa.pub) B) bash git is ignoring the changed HOME variable? Or maybe both.

I'm also not sure C) if arbitrarily changing the HOME variable like this is a good idea in general w.r.t other programs that might reference it?

Answer 1

So as Telastyn commented I added symlinks in WSLs ~/.ssh/ to the id_rsa and id_rsa.pub using:

> ln -s /mnt/c/Users/MyName/.ssh/id_rsa ~/.ssh/id_rsa
> ln -s /mnt/c/Users/MyName/.ssh/id_rsa.pub ~/.ssh/id_rsa.pub

Using the same technique to instead link the symlink directory as suggested by tripleee, I had issues until I saw that the trailing slashes I used in the ln command (left from using the tab key to have bash fill out the directory name) were an issue. Thus, instead of doing the above one could better do:

> ln -s /mnt/c/Users/Myname/.ssh ~/.ssh

The known_hosts file does differ slightly between my use of it (git in powershell using the ssh-agent) in Windows and the SSH use of it in WSL, whereby the host-name and IP are not hashed in the Windows version. According to the man page for ssh-config, there is a flag available to disable this hashing which I took to mean SSH would understand the file without the hashing which has worked out so far.

This latter method means that the details used for SSH used between the two different environments are exactly the same.

Thanks to Matěj Kříž for pointing out a small but vital missing character!

Answer 2

Based on the new build "Insider Build 17063" permissions for files works differently now. In short you need to do:

sudo umount /mnt/c
sudo mount -t drvfs C: /mnt/c -o metadata

This will make permissions for your ssh folder work as you need. Then procced as OP suggests in his answer.

Relevant links:

https://github.com/Microsoft/WSL/issues/3181 https://blogs.msdn.microsoft.com/commandline/2018/01/12/chmod-chown-wsl-improvements/

EDIT

I'm back to this question because I find out this is only temporary solution (yes I'm stupid). Each time you restart (logout) your WSL, you need to cast this commands again.

So the solution that works for me now is to edit (create) config file /etc/wsl.conf in my wsl ubuntu, and put inside following, then restart to do mounts again:

# Enable extra metadata options by default, set uid and gid to 0
[automount]
options = "metadata,uid=,gid="

Why I add metadata:

Linux permissions are added as additional metadata to the file. This means a file can have Linux and Windows read/write/execute permission bits.

Why set uid and gid:

By default, WSL sets the uid and gid to the value of the default user (in Ubuntu distro, the default user is created with uid=1000,gid=1000). If the user specifies a gid or uid option explicitly via this key, the associated value will be overwritten. Otherwise, the default value will always be appended.

Relevant links:

https://docs.microsoft.com/en-us/windows/wsl/wsl-config https://blogs.msdn.microsoft.com/commandline/2018/02/07/automatically-configuring-wsl/ https://blogs.msdn.microsoft.com/commandline/2018/01/12/chmod-chown-wsl-improvements/