Re: How to put a file in /gnu/store and set its permissions

[Gary Johnson]

> Nathan Dehnel <ncdehnel@gmail.com> writes:
>
> Thanks. I guess then I need to know how to put a file in /etc/ssh
> without putting it in the store.

> On Sun, Dec 5, 2021 at 8:44 PM Gary Johnson <lambdatronic@disroot.org> wrote:
>
> To programmatically add a file to /etc, you can extend the
> etc-service-type in your operating-system's services field like so:
>
> ```
> (use-modules
>  ((gnu services)         #:select (simple-service etc-service-type))
>  ((gnu services desktop) #:select (%desktop-services))
>  ((gnu system)           #:select (operating-system))
>  ((guix gexp)            #:select (local-file)))
>
> (define guixrig_host_rsa_key
>   (local-file "ssh/guixrig_host_rsa_key" #:recursive? #t))
>
> (operating-system
>  ...
>  (services (cons* (simple-service 'my-secret-service etc-service-type
>                                   `(("ssh/guixrig_host_rsa_key" 
> ,guixrig_host_rsa_key)))
>                   %desktop-services)))
> ```
>
> Have fun and happy hacking!
>   ~Gary

> Nathan Dehnel <ncdehnel@gmail.com> writes:
>
> Thanks. Though that code causes "guix system: error: symlink: File
> exists: "/etc/ssh"" when I use it, and by the looks of it, would still
> be putting the key in the store, which is insecure.

Bummer. It works as expected when I run that code on my system with:

```
sudo guix system reconfigure config.scm
```

Maybe you manually created /etc/ssh already, which could be causing the
error on your end? Either way, your file does end up in the store and is
owned by root:root with permissions 444.

I'm not aware of a way to add files to /etc or any other guix-managed
directory without placing a copy in the store. However, once your file
lands in /etc/ssh/guixrig_host_rsa_key, isn't it owned by root:root and
readable as well?

Perhaps one of the other Guix wizards on this mailing list would have
some ideas on how to control the permissions on these auto-generated
files.

Good luck,
  Gary

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