Understanding Qubes /rw folder

monkeychimpanzeefrog · April 5, 2024, 6:06pm

Can someone explain the logic behind the /rw folder for (disposable) templates?

For example: When following this guide, I do not understand, why files from /rw/config/NM-system-connections/ are resulting in files in /etc/NetworkManager/system-connections

This article does not even mention NM-system-connections

I did use search function and I have read Qubes documentation (sorry, can only post two links as new user): templates, disposable-customization, bind-dirs

apparatus · April 5, 2024, 6:18pm

It’s Qubes OS configuration.
Here’s the script that is making a link for the NM config files from /rw to /etc:

github.com

QubesOS/qubes-core-agent-linux/blob/main/network/network-manager-prepare-conf-dir

#!/bin/sh

# Source Qubes library.
# shellcheck source=init/functions
. /usr/lib/qubes/init/functions

if test -d /sys/fs/selinux; then enable_selinux=Z; else enable_selinux=''; fi
NM_CONFIG_DIR=/etc/NetworkManager/system-connections
if [ -d "$NM_CONFIG_DIR" ] && [ ! -h "$NM_CONFIG_DIR" ]; then
    mkdir "-p$enable_selinux" /rw/config/NM-system-connections
    mv ${enable_selinux:+-Z} "$NM_CONFIG_DIR"/* /rw/config/NM-system-connections/ 2> /dev/null || true
    rmdir "$NM_CONFIG_DIR"
    ln -s /rw/config/NM-system-connections "$NM_CONFIG_DIR"
fi

# Do not manage xen-provided network devices
unmanaged_devices=mac:fe:ff:ff:ff:ff:ff
#for mac in `xenstore-ls device/vif | grep mac | cut -d= -f2 | tr -d '" '`; do
#    unmanaged_devices="$unmanaged_devices;mac:$mac"
#done

This file has been truncated. show original

It’s this file in your template /lib/qubes/network-manager-prepare-conf-dir.

monkeychimpanzeefrog · April 5, 2024, 6:21pm

Wow, that was quick. Is there any way to have this knowledge without studying the source code of qubes? I guess something like this has been done for other things besides the network-manager?

apparatus · April 5, 2024, 6:25pm

I think there is no documentation available for every change.
For example, if you’re interested how NM-system-connections is used in a qube you could search this string inside the qube files and you’d find where is it used and then check the related files:

$ sudo grep -lr "NM-system-connections" /etc /lib/qubes*
/lib/qubes/network-manager-prepare-conf-dir