uacess vs root

[m1st0]

I was trying to look into required permissions. With some other keyboard LED projects, I've been able to work with hardware using udev rules in Ubuntu at /etc/udev/rules.d/ 51-hv-kb395l-keyboard.rules such as the following for that keyboard

ACTION=="add", SUBSYSTEM=="usb", ATTRS{idVendor}=="04d9", ATTRS{idProduct}=="a1dd", TAG+="uaccess"

or in the case of a Vulcan 121 AIMO I tried

ACTION=="add", SUBSYSTEM=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="3098", TAG+="uaccess"

Of course this was just a test and there are other needs in the software for more access rights over just the hardware. I was just wondering if we can go this route and remove the need for root access?

[X3n0m0rph59]

Hi @m1st0, thank you for your request!

It should be possible to remove the need for running as the root user. I believe that using the uaccess mechanism is not going to work out though.

I got it mostly working using a dedicated user and group (eruption), by performing the following steps:

# set up user
sudo useradd -r eruption -s /usr/sbin/nologin -d /
sudo usermod -a -G input eruption

# dirs and permissions
sudo mkdir /run/eruption
sudo chown eruption /run/eruption
sudo chown -R eruption:eruption /var/lib/eruption/

# permissions in /dev
sudo setfacl /dev/uinput -m u:eruption:rw 

# run eruption as non-root
sudo -u eruption -g eruption RUST_LOG=debug RUST_BACKTRACE=full target/debug/eruption -c support/config/eruption-dev.conf

support/udev/99-eruption.rules

# Stable links to Eruption virtual devices

ACTION=="add|change", ATTRS{name}=="Eruption Virtual Keyboard", SYMLINK+="input/by-id/eruption-virtual-keyboard"
ACTION=="add|change", ATTRS{name}=="Eruption Virtual Mouse", SYMLINK+="input/by-id/eruption-virtual-mouse"


ACTION=="change", GOTO="eruption_end"
ACTION=="remove", GOTO="eruption_end"


# check for presence of lock file

TEST=="/run/lock/eruption-hotplug-helper.lock", GOTO="eruption_end"


# Permissions

ACTION=="add|change", SUBSYSTEMS=="input", RUN+="/usr/bin/setfacl -m u:eruption:rw $env{DEVNAME}"


# Keyboard devices

# ROCCAT Vulcan 100/120/121
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="307a", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="3098", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"

# ROCCAT Vulcan Pro
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="30f7", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"

# ROCCAT Vulcan TKL
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="2fee", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"

# ROCCAT Vulcan Pro TKL
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="311a", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"

# ROCCAT Magma
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="3124", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"

# Corsair STRAFE Gaming Keyboard
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1b1c", ATTRS{idProduct}=="1b15", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"


# Mouse devices

# ROCCAT Kone Aimo
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="2e27", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"

# ROCCAT Kone Aimo Remastered
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="2e2c", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"

# ROCCAT Kone Pure Ultra
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="2dd2", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"

# ROCCAT Kone Pro Air
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="2c8e", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="2c92", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"

# ROCCAT Burst Pro
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="2de1", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"

# ROCCAT Kain 100
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="2d00", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"

# ROCCAT Kain 2xx
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="2d5f", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="2d60", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"

# ROCCAT Kova AIMO
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="2cf1", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="2cf3", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"

# ROCCAT Kova 2016
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="0x2cee", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="0x2cef", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="0x2cf0", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"

# ROCCAT Nyth
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="2e7c", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="2e7d", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"


# Miscellaneous devices

# ROCCAT/Turtle Beach Elo 7.1 Air
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="3a37", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"

# ROCCAT Aimo Pad Wide
ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1e7d", ATTRS{idProduct}=="343b", TAG+="systemd", ENV{SYSTEMD_WANTS}+="eruption-hotplug-helper.service", GROUP="eruption"

LABEL="eruption_end"

support/dbus/org.eruption.control.conf:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE busconfig PUBLIC
 "-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN"
 "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">

<!--
    This file is part of Eruption.

    Eruption is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    Eruption is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with Eruption.  If not, see <http://www.gnu.org/licenses/>.
-->

<busconfig>
  <!-- Only user root and user eruption can own the eruption.control service -->
  <policy user="root">
    <allow own="org.eruption"/>
  </policy>

  <policy user="eruption">
    <allow own="org.eruption"/>
  </policy>

  <!-- Allow anyone to call into the service -->
  <policy context="default">
    <allow send_destination="org.eruption"
           send_interface="org.eruption.Slot"/>
    <allow send_destination="org.eruption"
           send_interface="org.eruption.Profile"/>
    <allow send_destination="org.eruption"
           send_interface="org.eruption.Status"/>
    <allow send_destination="org.eruption"
           send_interface="org.eruption.Config"/>
    <allow send_destination="org.eruption"
           send_interface="org.eruption.Device"/>
    <allow send_destination="org.eruption"
           send_interface="org.freedesktop.DBus.Properties"/>
    <allow send_destination="org.eruption"
           send_interface="org.freedesktop.DBus.Introspectable"/>
    <allow send_destination="org.eruption"
           send_interface="org.freedesktop.DBus.Peer"/>
  </policy>
</busconfig>

I will try to polish the changes somewhat and then merge them to the master branch.

[m1st0]

Made a branch to test this, but can't build at the moment:

Updating git repository `https://github.com/X3n0m0rph59/pulsectl.git`
error: failed to select a version for the requirement `phf = "^0.11.0"`
candidate versions found which didn't match: 0.10.1, 0.10.0, 0.9.0, ...
location searched: crates.io index
required by package `csscolorparser v0.6.2`
    ... which satisfies dependency `csscolorparser = "^0.6.2"` (locked to 0.6.2) of package `eruption v0.2.0 (. . .)`
make: *** [Makefile:30: build] Error 101`

[Phen-Ro]

@m1st0 You'll need to use rustup to get the latest version of cargo. I went through the same trouble on Kubuntu 22.04. I don't know all the technical details, but the version format of packages has changed recently, and older versions of cargo can't parse the new format.

If you're in the same boat I was, just uninstall the package manager's version of rust, cargo, etc, then install the latest rust using rustup.