Re: [systemd-devel] WebUSB

[Simon McVittie]

On Mon, 09 Jan 2017 at 10:20:33 +0100, Lars Knudsen wrote:
> 2. make sure that webusb devices will be somehow accessible to be used by a
> browser running with user permissions (current temp solution listed here:
> adding user to plugdev, adding 0664 permissions to device: https://
> developers.google.com/web/updates/2016/03/access-usb-devices-on-the-web )  
> (udev/systemd task).

Since I didn't see a response to this: this sounds like a job for uaccess.
Most things that happened via the plugdev group (on Debian/derivatives)
5 or 10 years ago should happen via uaccess now.

TAG+="uaccess" in a udev rule results in an ACL being set so that
a currently-active logind session on the same seat can read and write
the device node.

S
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Re: [systemd-devel] User bus broke automatic multiseat

[Simon McVittie]

On Wed, 14 Dec 2016 at 23:23:55 +0300, Oleg Samarin wrote:
> The following change in systemd-226:
> 
> systemd now supports the concept of user buses replacing
> session buses, if used with dbus-1.10 (and enabled via dbus
> --enable-user-session). It previously only supported this on
> kdbus-enabled systems, and this release expands this to
> 'dbus-daemon' systems
> 
> totally broke the automatic multiseat with GDM: https://bugzilla.redhat
> .com/show_bug.cgi?id=1404849
> 
> What configuration options can restore the the old session-bus
> behavior?

Either don't configure dbus with --enable-user-session, or teach gdm
to create a per-display D-Bus bus for each of its X11 displays (or
Wayland equivalent).

For the former solution, see the split between the dbus and
dbus-user-session packages in Debian. dbus is always configured
with --enable-user-session there, but we split out the user-session parts
(basically /usr/lib/systemd/user) into dbus-user-session_*.deb so that
it's opt-in.

For the latter solution, the patch/script on the Red Hat bug you referenced
are implementations of the right sort of idea. Please talk to the gdm (GNOME)
developers about the best way to integrate that.

S
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Re: [systemd-devel] question regarding DBUS_SESSION_BUS_ADDRESS in multiseat environment

[Simon McVittie]

On Sat, 03 Dec 2016 at 11:18:43 +0530, MohanR wrote:
> I'm looking through this --enable-user-session in dbus-daemon. Even if
> I enable that option, how can I retrive uniq DBUS_SESSION_BUS_ADDRESS
> from systemd started dbus-daemon to pass it to gnome-session?

I suggest taking a look at how it has been done in an OS distribution that
integrates --enable-user-session, such as Debian (with the dbus-user-session
package), Fedora or Arch Linux.

The socket used for the systemd-started dbus-daemon is predictable per-uid,
and recent versions of the major D-Bus implementations (libdbus, GDBus,
sd-bus) all try that socket before autostarting a new one.

Setting DBUS_SESSION_BUS_ADDRESS is only necessary to be nice to minor
D-Bus implementations (ndesk-dbus, dbus-java, etc.) or programs that
second-guess how D-Bus works (which currently includes gnome-session,
).

S
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