Lock screen bypassed by switching to console and then back to GUI

[hussain]

[Impact]

When I lock the screen I found that switching to console and then using ctrl+alt+F7 to switch back to GUI bypasses the lock screen without typing any password. even when I click on switch user after locking the screen if replicate the same process it takes me to the locked user account without prompting for password.

[Test Case]

- Make sure On Screen Keyboard is enabled under Universal Access in System
  Settings
- Lock the screen either from the gui or even using a terminal command.
- switch to a tty i.e ctrl + alt + f4
- Switch back to gui ctrl + alt + F7

ubuntu 15.10.
unity desktop.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: lightdm 1.16.7-0ubuntu1
ProcVersionSignature: Ubuntu 4.2.0-27.32-generic 4.2.8-ckt1
Uname: Linux 4.2.0-27-generic x86_64
ApportVersion: 2.19.1-0ubuntu5
Architecture: amd64
CurrentDesktop: Unity
Date: Thu Mar 3 07:19:08 2016
InstallationDate: Installed on 2015-11-09 (114 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
SourcePackage: lightdm
UpgradeStatus: No upgrade log present (probably fresh install)

[Seth Arnold (seth-arnold)]

I can't reproduce this; do you perhaps have any of the settings allowing logging in without password or unlocking/resuming without a password configured? Poke around the System Settings, in the brightness and lock, security and privacy, and user account tabs.

Thanks

[hussain (abuznb195)]

All the settings are set to require password. and sure enough it does prompt for a password but it can be bypassed by the steps I mentioned.

[Peeter P. Mõtsküla (ppmotskula)]

I just reproduced it on latest Xenial.

[Seth Arnold (seth-arnold)]

Peeter, Hussain, could you guys give some directions on how to reproduce this issue after a fresh install into a VM?

Thanks

[Marco Trevisan (Treviño) (3v1n0)]

hussain, Peeter can you reproduce that everytime regurarly?

Before doing the tty switch, please in a terminal run:
  gdbus monitor --system --dest org.freedesktop.login1 &
  gdbus monitor --session --dest com.canonical.Unity

And let us know what happens

[hussain (abuznb195)]

I don't know what happened but my problem was solved after I did the following :

I tried changing the lock screen to something that looks similar to the login greeter. At first it didn't work.
After a while I had a problem with the panel and launcher not showing up in my account. So I created a new user and I was surprised that the lock screen change worked. So I try to bypass the lock screen and I discover that I can't do it anymore.

In answer to your question: yes I could reproduce it every single time before changing the lock screen.

[Marco Trevisan (Treviño) (3v1n0)]

Ouch... Having a broken system would have been good for debugging.

[Alex (athewsey)]

I'm currently experiencing this on 15.10. Any data I can provide to help?

[Marco Trevisan (Treviño) (3v1n0)]

Alex, could you do what I've explained on comment #6 (https://bugs.launchpad.net/ubuntu/+source/unity/+bug/1552537/comments/6).

Also providing your auth.log could help.

[Peeter P. Mõtsküla (ppmotskula)]

Marco, I can reproduce that with 100% reliability on my 16.04 beta (with all the updates installed). When I see the auth dialog (i.e. after locking the screen or returning from sleep), I hit ctrl+alt+F6 ctrl+alt+F7 and gain access to my system. During the process, nothing at all gets added to /var/log/auth.log

user@host:~$ gdbus monitor --system --dest org.freedesktop.login1 & gdbus monitor --session --dest com.canonical.Unity
[1] 26646
Monitoring signals from all objects owned by org.freedesktop.login1
The name org.freedesktop.login1 is owned by :1.4
Monitoring signals from all objects owned by com.canonical.Unity
The name com.canonical.Unity is owned by :1.14
/org/freedesktop/login1/session/c2: org.freedesktop.DBus.Properties.PropertiesChanged ('org.freedesktop.login1.Session', {'IdleHint': <true>, 'IdleSinceHint': <uint64 1459227675096697>, 'IdleSinceHintMonotonic': <uint64 11646057942>}, @as [])
/org/freedesktop/login1/seat/seat0: org.freedesktop.DBus.Properties.PropertiesChanged ('org.freedesktop.login1.Seat', {'IdleHint': <true>, 'IdleSinceHint': <uint64 1459227675096697>, 'IdleSinceHintMonotonic': <uint64 11646057942>}, @as [])
/org/freedesktop/login1/user/_1000: org.freedesktop.DBus.Properties.PropertiesChanged ('org.freedesktop.login1.User', {'IdleHint': <true>, 'IdleSinceHint': <uint64 1459227675096697>, 'IdleSinceHintMonotonic': <uint64 11646057942>}, @as [])
/org/freedesktop/login1: org.freedesktop.DBus.Properties.PropertiesChanged ('org.freedesktop.login1.Manager', {'IdleHint': <true>, 'IdleSinceHint': <uint64 1459227675096697>, 'IdleSinceHintMonotonic': <uint64 11646057942>}, @as [])
/org/freedesktop/login1/session/c2: org.freedesktop.DBus.Properties.PropertiesChanged ('org.freedesktop.login1.Session', {'Active': <false>}, @as [])
/org/freedesktop/login1/seat/seat0: org.freedesktop.DBus.Properties.PropertiesChanged ('org.freedesktop.login1.Seat', {'ActiveSession': <('', objectpath '/')>}, @as [])
/org/freedesktop/login1/session/c2: org.freedesktop.DBus.Properties.PropertiesChanged ('org.freedesktop.login1.Session', {'Active': <true>}, @as [])
/org/freedesktop/login1/seat/seat0: org.freedesktop.DBus.Properties.PropertiesChanged ('org.freedesktop.login1.Seat', {'ActiveSession': <('c2', objectpath '/org/freedesktop/login1/session/c2')>}, @as [])
/org/freedesktop/login1/session/c2: org.freedesktop.DBus.Properties.PropertiesChanged ('org.freedesktop.login1.Session', {'IdleHint': <false>, 'IdleSinceHint': <uint64 1459227691145076>, 'IdleSinceHintMonotonic': <uint64 11662106321>}, @as [])
/org/freedesktop/login1/seat/seat0: org.freedesktop.DBus.Properties.PropertiesChanged ('org.freedesktop.login1.Seat', {'IdleHint': <false>, 'IdleSinceHint': <uint64 1459227691145076>, 'IdleSinceHintMonotonic': <uint64 11662106321>}, @as [])
/org/freedesktop/login1/user/_1000: org.freedesktop.DBus.Properties.PropertiesChanged ('org.freedesktop.login1.User', {'IdleHint': <false>, 'IdleSinceHint': <uint64 1459227691145076>, 'IdleSinceHintMonotonic': <uint64 11662106321>}, @as [])
/org/freedesktop/login1: org.freedesktop.DBus.Properties.PropertiesChanged ('org.freedesktop.login1.Manager', {'IdleHint': <false>, 'IdleSinceHint': <uint64 1459227691145076>, ...

[Andrea Azzarone (azzar1)]

Can you please check if in the system settings the "On Screen Keyboard" is enabled?

[hussain (abuznb195)]

When I had the problem on screen keyboard was enabled. And it shows up upon signing in.

[Peeter P. Mõtsküla (ppmotskula)]

Checked. On my system, the bug only manifests itself when on-screen keyboard (onboard) is enabled.

[Andrea Azzarone (azzar1)]

Ok, a fix has already been proposed. Thanks.

[Launchpad Janitor (janitor)]

This bug was fixed in the package unity - 7.4.0+16.04.20160415-0ubuntu1

---------------
unity (7.4.0+16.04.20160415-0ubuntu1) xenial; urgency=medium

  [ Andrea Azzarone ]
  * Do not use pointers to LazyLoadTextures. (LP: #1569100)
  * Fix unity script crash. (LP: #1566565)
  * LockscreenController: Don't use SetActivate(False) for gnome-
    screensaver to prevent unlocking on tty switch. It will not only
    deactivate the screensaver but also unlock the screen. (LP:
    #1552537)
  * unityshell.xml: Fix typo (LP: #1559427)

 -- Marco Trevisan (Treviño) <[e-mail]> Fri, 15 Apr 2016 05:33:08 +0000

[Martin Pitt (pitti)]

Hello hussain, or anyone else affected,

Accepted unity into trusty-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/unity/7.2.6+14.04.20160408-0ubuntu1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Marco Trevisan (Treviño) (3v1n0)]

Anyone can test this for Trusty SRU?

[Mathew Hodson (mhodson)]

I reproduced this issue in Trusty, but it is still broken with unity/7.2.6+14.04.20160408-0ubuntu1

Another issue I found is that while On Screen Keyboard is enabled, the Lock shortcut doesn't work and neither does selecting Lock from the menu or when logging out.

To test, what I did was switch to Guest Session and then log out to get to the lock screen.

$ apt list --installed unity unity-services libunity-core-6.0-9
Listing... Done
libunity-core-6.0-9/now 7.2.6+14.04.20160408-0ubuntu1 amd64 [installed,local]
unity/now 7.2.6+14.04.20160408-0ubuntu1 amd64 [installed,local]
unity-services/now 7.2.6+14.04.20160408-0ubuntu1 amd64 [installed,local]

[Andrea Azzarone (azzar1)]

@Mathew I cannot understand from your comment if you marked the bug as verification-failed because you fail to lock the screen or beucase you can bypass as described in the description.

[Mathew Hodson (mhodson)]

I was able to bypass the lockscreen as described in the description.

The lock command failing is another issue that appeared for me when On Screen Keyboard is enabled. I mentioned it because it makes the test somewhat different. I was still able to test the bypass by switching to Guest Session and then logging out to get to the lock screen.

[Andrea Azzarone (azzar1)]

Are you sure are you running the last version? Did you restart (actually a logout is enough) after the upgrade?

[Mathew Hodson (mhodson)]

I did do a system restart before I tested, and I was using unity/7.2.6+14.04.20160408-0ubuntu1 from -proposed.

[Martin Pitt (pitti)]

So this is "just" this bug not being fixed still, but not actually a regression. I'll release this update to fix bug 1568031 and will then reopen this.

[Martin Pitt (pitti)]

The verification of the Stable Release Update for unity has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

[Launchpad Janitor (janitor)]

This bug was fixed in the package unity - 7.2.6+14.04.20160408-0ubuntu1

---------------
unity (7.2.6+14.04.20160408-0ubuntu1) trusty; urgency=medium

  [ Andrea Azzarone ]
  * Don't use SetActivate from gnome-screensaver as it will not only
    deactivate the screensaver but also unlock the screen. (LP:
    #1552537)
  * Improve the "lock on suspend" logic to always keep in sync the
    inhibitor with the lockscreen. (LP: #1568031)

 -- Marco Trevisan (Treviño) <[e-mail]> Fri, 08 Apr 2016 16:34:44 +0000

[Martin Pitt (pitti)]

Reopening trusty task, see above. Sorry for the "fix released" noise, this cannot be avoided due to releasing the package for the other bug.