[Pkg-xfce-devel] Bug#887773: It is possible to circumvent authentication after locking screen in lightdm

[Matsievskiy S.V.]

Package: lightdm
Version: 1.18.3-4
Followup-For: Bug #887773

Dear Maintainer,

I had the same problem with lightdm. Installing light-locker seems to be
solving it.
If I lock and switch ttys without light-locker, lightdm creates a new seat.
Here is the output of the systemctl for it:

● lightdm.service - Light Display Manager
   Loaded: loaded (/lib/systemd/system/lightdm.service; indirect; vendor
preset: enabled)
   Active: active (running) since Sat 2018-03-03 10:37:53 MSK; 16min ago
     Docs: man:lightdm(1)
 Main PID: 848 (lightdm)
    Tasks: 10 (limit: 4915)
   CGroup: /system.slice/lightdm.service
           ├─  848 /usr/sbin/lightdm
           ├─  925 /usr/lib/xorg/Xorg :0 -seat seat0 -auth
/var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
           ├─27023 /usr/lib/xorg/Xorg :1 -seat seat0 -auth
/var/run/lightdm/root/:1 -nolisten tcp vt8 -novtswitch
           └─27091 lightdm --session-child 13 22

With light-locker running everything seems to work as expected. No additional
seat is created.

● lightdm.service - Light Display Manager
   Loaded: loaded (/lib/systemd/system/lightdm.service; indirect; vendor
preset: enabled)
   Active: active (running) since Sat 2018-03-03 10:54:58 MSK; 1min 20s ago
     Docs: man:lightdm(1)
  Process: 27948 ExecStartPre=/bin/sh -c [ "$(cat /etc/X11/default-display-
manager 2>/dev/null)" = "/usr/sbin/lightdm" ] (code=exited, status=0/SUCCESS)
 Main PID: 27950 (lightdm)
    Tasks: 6 (limit: 4915)
   CGroup: /system.slice/lightdm.service
           ├─27950 /usr/sbin/lightdm
           └─27955 /usr/lib/xorg/Xorg :0 -seat seat0 -auth
/var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch



-- System Information:
Debian Release: buster/sid
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'testing'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.14.0-3-amd64 (SMP w/8 CPU cores)
Locale: LANG=en_GB.utf8, LC_CTYPE=en_GB.utf8 (charmap=UTF-8), LANGUAGE=en_GB.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages lightdm depends on:
ii  adduser                                3.117
ii  dbus                                   1.12.4-1
ii  debconf [debconf-2.0]                  1.5.65
ii  libaudit1                              1:2.8.2-1
ii  libc6                                  2.26-6
ii  libgcrypt20                            1.8.1-4
ii  libglib2.0-0                           2.54.3-2
ii  libpam-systemd                         236-3
ii  libpam0g                               1.1.8-3.7
ii  libxcb1                                1.12-1
ii  libxdmcp6                              1:1.1.2-3
ii  lightdm-gtk-greeter [lightdm-greeter]  2.0.4-1
ii  lsb-base                               9.20170808

Versions of packages lightdm recommends:
ii  xserver-xorg  1:7.7+19

Versions of packages lightdm suggests:
ii  accountsservice  0.6.45-1
ii  upower           0.99.7-2
ii  xserver-xephyr   2:1.19.6-1

-- debconf information:
* shared/default-x-display-manager: lightdm
  lightdm/daemon_name: /usr/sbin/lightdm