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@ -8,14 +8,19 @@ redirect_from:
# How to make any file in a TemplateBasedVM persistent using bind-dirs #
## What is bind-dirs.sh? ##
## What is bind-dirs? ##
With [bind-dirs.sh](https://github.com/QubesOS/qubes-core-agent-linux/blob/master/vm-systemd/bind-dirs.sh)
you can make arbitrary files or folders persistent in TemplateBasedVMs.
With [bind-dirs](https://github.com/QubesOS/qubes-core-agent-linux/blob/master/vm-systemd/bind-dirs.sh)
any arbitrary files or folders can be made persistent in TemplateBasedVMs.
## What is it useful for? ##
For example, it is useful for Whonix, sys-whonix, where [Tor's data dir /var/lib/tor has been made persistent in the TemplateBased ProxyVM sys-whonix](https://github.com/Whonix/qubes-whonix/blob/8438d13d75822e9ea800b9eb6024063f476636ff/usr/lib/qubes-bind-dirs.d/40_qubes-whonix.conf#L5). So sys-whonix does not require to be a StandaloneVM. And therefore can benefit from the Tor anonymity feature 'persistent Tor entry guards' without the overhead of a StandaloneVM.
In a TemplateBasedVM all of the file system comes from the template except /home and /usr/local.
This means that changes in the rest of the filesystem are lost when the TemplateBasedVM is shutdown.
bind-dirs provides a mechanism whereby files usually taken from the template can be persisted across reboots.
For example, in Whonix, [Tor's data dir /var/lib/tor has been made persistent in the TemplateBased ProxyVM sys-whonix](https://github.com/Whonix/qubes-whonix/blob/8438d13d75822e9ea800b9eb6024063f476636ff/usr/lib/qubes-bind-dirs.d/40_qubes-whonix.conf#L5).
In this way sys-whonix can benefit from the Tor anonymity feature 'persistent Tor entry guards' but does not have to be a StandaloneVM.
## Minimum Qubes Version ##
@ -29,26 +34,18 @@ Inside your TemplateBasedVM.
sudo mkdir -p /rw/config/qubes-bind-dirs.d
2. Create a file `/rw/config/qubes-bind-dirs.d/50_user.conf` with root rights inside a VM.
2. Create a file `/rw/config/qubes-bind-dirs.d/50_user.conf` with root rights inside a TemplateBasedVM.
sudo nano /rw/config/qubes-bind-dirs.d/50_user.conf
3. Append a folder or file to the `binds` variable. In the following example we are using folder `/var/lib/tor`. You can replace that folder with a folder of your choice.
binds+=( '/var/lib/tor' )
In the following example we are using file `/etc/tor/torrc`. You can replace that file with a file of your choice.
binds+=( '/etc/tor/torrc' )
Multiple configuration lines, files and folders supported. For example, you could use both.
3. Edit the file 50_user.conf to append a folder or file name to the `binds` variable. (In the following example we are using folder `/var/lib/tor`. You can replace that name with a folder or file name of your choice.)
binds+=( '/var/lib/tor' )
binds+=( '/etc/tor/torrc' )
Multiple entries are possible, each on a separate line.
4. Save.
5. Reboot your TemplateBasedVM.
5. Reboot the TemplateBasedVM.
6. Done.
@ -60,16 +57,32 @@ If you added for example folder `/var/lib/tor` to the `binds` variable, from now
* `/etc/qubes-bind-dirs.d` (intermediate priority, for template wide configuration)
* `/rw/config/qubes-bind-dirs.d` (highest priority, for per VM configuration)
## How does it work? ##
bind-dirs.sh is called on startup of a TemplateBasedVM, and configuration files in the configuration folders above are parsed to build a bash array.
Files or folders identified in the array are copied to /rw/bind-dirs if they do not already exist there, and are then bind mounted over the original files/folders.
Creation of the file and folders in /rw/bind-dirs should be automatic the first time the TemplateBasedVM is restarted after configuration.
If you want to circumvent this process, you can create the relevant filestructure under /rw/bind-dirs and make any changes at the same time that you perform the configuration, before reboot.
## Limitations ##
* Files that exist in the TemplateVM root image cannot be made deleted in the TemplateBasedVMs root image using bind-dirs.sh.
* Does not work if the file / folder in question does not already exist in the root image. I.e. a file that does not exist in the root image cannot be bind mounted in the TemplateBasedVM.
* Re-running `sudo /usr/lib/qubes/bind-dirs.sh` without previous `sudo /usr/lib/qubes/bind-dirs.sh umount` does not work.
* Running `sudo /usr/lib/qubes/bind-dirs.sh umount` after boot (before shutdown) is probably not sane and nothing can be done about that.
* Files that exist in the TemplateVM root image cannot be deleted in the TemplateBasedVMs root image using bind-dirs.sh.
* The file / folder in question must already exist in the root image. I.e. a file that does not exist in the root image cannot be bind mounted in the TemplateBasedVM.
* Re-running `sudo /usr/lib/qubes/bind-dirs.sh` without a previous `sudo /usr/lib/qubes/bind-dirs.sh umount` does not work.
* Running 'sudo /usr/lib/qubes/bind-dirs.sh umount' after boot (before shutdown) is probably not sane and nothing can be done about that.
* Many editors create a temporary file and copy it over the original file. If you have bind mounted an individual file this will break the mount.
Any changes you make will not survive a reboot. If you think it likely you will want to edit a file, then either include the parent directory in bind-dirs.rather than the file, or perform the file operation on the file in /rw/bind-dirs.
* Some files are altered when a qube boots - e.g. /etc/hosts. If you try to use bind-dirs on such files you may break your qube in unpredictable ways.
## How to remove binds from bind-dirs.sh? ##
`binds` is actually just a bash variable (an array) and the bind-dirs.sh configuration folders are `source`d as bash snippets in lexical order. Therefore if you wanted to remove an existing entry from the `binds` array, you could do that by using a lexically higher configuration file. For example, if you wanted to make `/var/lib/tor` non-persistent in `sys-whonix` without manually editing [`/usr/lib/qubes-bind-dirs.d/40_qubes-whonix.conf`](https://github.com/Whonix/qubes-whonix/blob/master/usr/lib/qubes-bind-dirs.d/40_qubes-whonix.conf), you could use the following.
`binds` is actually just a bash variable (an array) and the bind-dirs.sh configuration folders are `source`d as bash snippets in lexical order.
Therefore if you wanted to remove an existing entry from the `binds` array, you could do that by using a lexically higher configuration file.
For example, if you wanted to make `/var/lib/tor` non-persistant in `sys-whonix` without manually editing [`/usr/lib/qubes-bind-dirs.d/40_qubes-whonix.conf`](https://github.com/Whonix/qubes-whonix/blob/master/usr/lib/qubes-bind-dirs.d/40_qubes-whonix.conf), you could use the following.
`/rw/config/qubes-bind-dirs.d/50_user.conf`