Bug#939389: light-locker: Does not work in buster with xfce4

Anton Ivanov

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Sep 4, 2019, 7:20:03 AM9/4/19

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Package: light-locker
Version: 1.8.0-3
Severity: important

Dear Maintainer,

Fails to start with the following message:

ERROR **: 11:46:17.929: session_id is not set, is /proc mounted with hidepid>0?

Looks like this bug: https://github.com/the-cavalry/light-locker/issues/141

-- System Information:
Debian Release: 10.0
APT prefers stable-updates
APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.19.0-5-amd64 (SMP w/12 CPU cores)
Kernel taint flags: TAINT_UNSIGNED_MODULE
Locale: LANG=en_GB.utf8, LC_CTYPE=en_GB.utf8 (charmap=UTF-8), LANGUAGE=en_GB:en (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages light-locker depends on:
ii dconf-gsettings-backend [gsettings-backend] 0.30.1-2
ii libc6 2.28-10
ii libcairo2 1.16.0-4
ii libdbus-1-3 1.12.16-1
ii libdbus-glib-1-2 0.110-4
ii libglib2.0-0 2.58.3-2
ii libgtk-3-0 3.24.5-1
ii libpango-1.0-0 1.42.4-7~deb10u1
ii libpangocairo-1.0-0 1.42.4-7~deb10u1
ii libsystemd0 241-5
ii libx11-6 2:1.6.7-1
ii libxext6 2:1.3.3-1+b2
ii libxss1 1:1.2.3-1
ii lightdm 1.26.0-4

light-locker recommends no packages.

light-locker suggests no packages.

-- no debconf information

Yves-Alexis Perez

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Sep 4, 2019, 7:30:03 AM9/4/19

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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

On Wed, 2019-09-04 at 11:51 +0100, Anton Ivanov wrote:
> Fails to start with the following message:
>
> ERROR **: 11:46:17.929: session_id is not set, is /proc mounted with
> hidepid>0?
>
> Looks like this bug: https://github.com/the-cavalry/light-locker/issues/141

And do you have /proc mounted with hidepid>0?

Regards,
- --
Yves-Alexis
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Anton Ivanov

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Sep 4, 2019, 8:20:02 AM9/4/19

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I do not.

It is mounted normally and light-locker worked fine before the upgrade
to buster.

A

--
Anton R. Ivanov
https://www.kot-begemot.co.uk/

Yves-Alexis Perez

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Sep 4, 2019, 12:30:03 PM9/4/19

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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

On Wed, 2019-09-04 at 12:47 +0100, Anton Ivanov wrote:
> I do not.
>
> It is mounted normally and light-locker worked fine before the upgrade
> to buster.

In your session, is XDG_SESSION_ID set (and to what)? Could you give us the
debug output?

Regards,
- --
Yves-Alexis
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Anton Ivanov

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Sep 4, 2019, 12:40:04 PM9/4/19

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On 04/09/2019 17:18, Yves-Alexis Perez wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA256
>
> On Wed, 2019-09-04 at 12:47 +0100, Anton Ivanov wrote:
>> I do not.
>>
>> It is mounted normally and light-locker worked fine before the upgrade
>> to buster.
> In your session, is XDG_SESSION_ID set (and to what)?

No

These are the XDG environment variables:

XDG_CONFIG_DIRS=/etc/xdg
XDG_CURRENT_DESKTOP=XFCE
XDG_DATA_DIRS=/usr/share/xfce4:/usr/local/share/:/usr/share/:/usr/share
XDG_GREETER_DATA_DIR=/var/lib/lightdm/data/aivanov
XDG_MENU_PREFIX=xfce-
XDG_SEAT=seat0
XDG_SEAT_PATH=/org/freedesktop/DisplayManager/Seat0
XDG_SESSION_DESKTOP=lightdm-xsession
XDG_SESSION_PATH=/org/freedesktop/DisplayManager/Session14
XDG_SESSION_TYPE=x11
XDG_VTNR=7

> Could you give us the
> debug output?

light-locker --debug

** (light-locker:8185): ERROR **: 17:36:51.025: session_id is not set,

is /proc mounted with hidepid>0?

Trace/breakpoint trap

>
> Regards,
> - --
> Yves-Alexis
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Yves-Alexis Perez

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Sep 4, 2019, 2:50:02 PM9/4/19

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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

control: tag -1 unreproducible moreinfo

On Wed, 2019-09-04 at 17:37 +0100, Anton Ivanov wrote:
> No
>
> These are the XDG environment variables:
>
> XDG_CONFIG_DIRS=/etc/xdg
> XDG_CURRENT_DESKTOP=XFCE
> XDG_DATA_DIRS=/usr/share/xfce4:/usr/local/share/:/usr/share/:/usr/share
> XDG_GREETER_DATA_DIR=/var/lib/lightdm/data/aivanov
> XDG_MENU_PREFIX=xfce-
> XDG_SEAT=seat0
> XDG_SEAT_PATH=/org/freedesktop/DisplayManager/Seat0
> XDG_SESSION_DESKTOP=lightdm-xsession
> XDG_SESSION_PATH=/org/freedesktop/DisplayManager/Session14
> XDG_SESSION_TYPE=x11
> XDG_VTNR=7

So there's definitely something fishy, because lightdm should definitely set
XDG_SESSION_ID. Try looking at lightdm logs maybe?

- --
Yves-Alexis
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Anton Ivanov

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Sep 5, 2019, 2:40:03 AM9/5/19

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I tried to trace it sticking debug echoes into Xsession.d scripts

It is not set to start off with and even if it was
95dbus_update-activation-env

will unset it. Lines 8-10 in that are:

    unset XDG_SEAT
    unset XDG_SESSION_ID
    unset XDG_VTNR

A.

Yves-Alexis Perez

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Sep 5, 2019, 3:50:03 AM9/5/19

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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

On Thu, 2019-09-05 at 07:28 +0100, Anton Ivanov wrote:
> It is not set to start off with and even if it was
> 95dbus_update-activation-env
>
> will unset it. Lines 8-10 in that are:
>
> unset XDG_SEAT
> unset XDG_SESSION_ID
> unset XDG_VTNR

This is done in a subshell and shouldn't touch the parent environment.

XDG_SESSION_ID should be set to the logind session, so it's likely *something*
in your environment is wrong, but I have no idea which and you'll have to
investigate yourself (it works just fine on other Buster boxes I have).

Note that if you don't have a logind session (check with loginctl) it's likely
other stuff won't work correctly. Just in case, make sure libpam-systemd is
installed.

Regards,

- --
Yves-Alexis
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Anton Ivanov

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Sep 5, 2019, 4:20:04 AM9/5/19

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On 05/09/2019 08:43, Yves-Alexis Perez wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA256
>
> On Thu, 2019-09-05 at 07:28 +0100, Anton Ivanov wrote:
>> It is not set to start off with and even if it was
>> 95dbus_update-activation-env
>>
>> will unset it. Lines 8-10 in that are:
>>
>> unset XDG_SEAT
>> unset XDG_SESSION_ID
>> unset XDG_VTNR
> This is done in a subshell and shouldn't touch the parent environment.
>
> XDG_SESSION_ID should be set to the logind session, so it's likely *something*
> in your environment is wrong, but I have no idea which and you'll have to
> investigate yourself (it works just fine on other Buster boxes I have).
>
> Note that if you don't have a logind session (check with loginctl) it's likely
> other stuff won't work correctly. Just in case, make sure libpam-systemd is
> installed.

That looks to be the case and it is something specific to upgrade. I do
not see the user session using loginctl, only the root console logins.

I do not recall having any of these issues on a clean buster install.

I will continue digging, thanks for your help.

>
> Regards,
> - --
> Yves-Alexis
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Anton Ivanov

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Sep 5, 2019, 6:50:03 AM9/5/19

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Root cause:

systemd-login service does not work in a NIS environment without nscd
installed.

It ends up doing a yp call which is TCP and that is prohibited by
configuration. The call fails, a rather meaningless error is returned
and pam_systemd fails to setup session. It does not prevent a login
because session setup is marked as optional in the corresponding pam files.

Installing nscd bypasses this because it will be going over the nscd
unix domain socket which is allowed

IMHO this as a workaround is NOT stable and not guaranteed to work. The
config for logind should be relaxed to allow it TCP calls in order to
function correctly in PAM environments which use network authentication.

Brgds,

A.

On 05/09/2019 07:33, Debian Bug Tracking System wrote:
> Thank you for the additional information you have supplied regarding
> this Bug report.
>
> This is an automatically generated reply to let you know your message
> has been received.
>
> Your message is being forwarded to the package maintainers and other
> interested parties for their attention; they will reply in due course.
>
> Your message has been sent to the package maintainer(s):
> Debian Xfce Maintainers <debia...@lists.debian.org>
>
> If you wish to submit further information on this problem, please
> send it to 939...@bugs.debian.org.
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