On s390x and ppc64, the permissions of the /dev/kvm device are currently
not right as long as the kvm kernel module has not been loaded yet. The
kernel module is using MODULE_ALIAS("devname:kvm") there, so the module
will be loaded on the first access to /dev/kvm. In that case, udev needs
to apply the permission to the static node already (which was created via
devtmpfs), i.e. we have to specify the option "static_node=kvm" in the
udev rule.
Note that on x86, the kvm kernel modules are loaded early instead (via the
MODULE_DEVICE_TABLE(x86cpu, ...) feature checking), so that the right module
is loaded for the Intel or AMD hypervisor extensions right from the start.
Thus the "static_node=kvm" is not required on x86 - but it also should not
hurt here (and using it here even might be more future proof in case the
module loading is also done delayed there one day), so we just add the new
option to the rule here unconditionally.
- Remove the uaccess tag from /dev/dri/renderD*.
- Change the owning group from video to render.
- Change default mode to 0666.
- Add an option to allow users to set the access mode for these devices at
compile time.
Freescale IMX SoCs serial ports driven by kernel "imx-uart" driver have
names of "ttymxcN", let's add this pattern to an udev rule for serial
ports so they will have proper ownership applied.
This places the input_id call after the evdev hwdb calls. With this the
hwdb fixups in evdev can affect the device capabilities assigned in
input_id.
Remove the ID_INPUT_KEY dependency in atkbd rule because it is now not
assigned at this point.
The /dev/mediaX and /dev/cecX devices belong to the video group.
Add two default rules for that.
The /dev/cecX devices were introduced in kernel 4.8 in staging and moved
out of staging in 4.10. These devices support the HDMI CEC bus.
The /dev/mediaX devices are much older, but because they are not used very
frequently nobody got around to adding this rule to systemd. They let the
user control complex media pipelines.
Kernel default mode is 0600, but distributions change it to group kvm, mode
either 0660 (e.g. Debian) or 0666 (e.g. Fedora). Both approaches have valid
reasons (a stricter mode limits exposure to bugs in the kvm subsystem, a looser
mode makes libvirt and other virtualization mechanisms work out of the box for
unprivileged users over ssh).
In Fedora the qemu package carries the relevant rule, but it's nicer to have it
in systemd, so that the permissions are not dependent on the qemu package being
installed. Use of packaged qemu binaries is not required to make use of
/dev/kvm, e.g. it's possible to use a self-compiled qemu or some alternative.
https://bugzilla.redhat.com/show_bug.cgi?id=1431876
To accomodate both approaches, add a rule to set the mode in 50-udev-default.rules,
but allow the mode to be overridden with a --with-dev-kvm-mode configure rule.
The default is 0660, as the (slightly) more secure option.
2017-03-27 12:34:24 +02:00
Renamed from rules/50-udev-default.rules (Browse further)
Thomas Huth