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[Bug 1517685] Re: XDMCP server starts without authentication if configured key does not exist

 

This bug was fixed in the package lightdm - 1.14.4-0ubuntu1

---------------
lightdm (1.14.4-0ubuntu1) vivid; urgency=medium

  * New upstream release:
    - Handle XDMCP Request packet with no addresses. (LP: #1516831)
    - Don't start LightDM if the XDMCP server is configured with a key that
      doesn't exist. (LP: #1517685)
    - Add IP addresses to XDMCP log messages.
    - Refactor XDMCP error handling.
    - Add more tests.

 -- Robert Ancell <robert.ancell@xxxxxxxxxxxxx>  Fri, 20 Nov 2015
16:01:15 +1300

** Changed in: lightdm (Ubuntu Vivid)
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/1517685

Title:
  XDMCP server starts without authentication if configured key does not
  exist

Status in Light Display Manager:
  Fix Released
Status in Light Display Manager 1.10 series:
  Fix Released
Status in Light Display Manager 1.14 series:
  Fix Released
Status in Light Display Manager 1.16 series:
  Fix Released
Status in Light Display Manager 1.2 series:
  Fix Released
Status in lightdm package in Ubuntu:
  Fix Released
Status in lightdm source package in Precise:
  Confirmed
Status in lightdm source package in Trusty:
  Fix Released
Status in lightdm source package in Vivid:
  Fix Released
Status in lightdm source package in Wily:
  Fix Released

Bug description:
  [Impact]
  An incorrectly configured XDMCP server will start without authentication instead of disabling XDMCP / stopping LightDM.

  [Test Case]
  1. Set up LightDM to run an XDMCP server using an XDM authentication key, i.e. in lightdm.conf:
  [XDMCPServer]
  enabled=true
  key=key-name
  2. Do not create /etc/lightdm/keys.conf or do not define 'key-name' in keys.conf.
  3. Start LightDM
  4. Connect XDMCP client.

  Expected result:
  Either LightDM doesn't start or the XDMCP server doesn't start.

  Observed result:
  XDMCP server starts without authentication, any XDMCP client is able to connect. Debug message printed to log warning about missing key, but not easy to spot.

  [Regression Potential]
  Low - change is to not start LightDM if this case occurs. This could affect someone who currently has a misconfigured LightDM. In this case a warning message is printed to the log.

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