pam_tty_audit failed in pam_open_session

Status changed to 'Confirmed' because the bug affects multiple users.

Please see https://wiki.ubuntu.com/SponsorshipProcess and https://wiki.ubuntu.com/StableReleaseUpdates#Procedure if you can volunteer to get the fix landed. Note that I don't expect anyone to work on this any time soon. It needs volunteers.

Attached patch (which is based on pam_1.1.8-3.6ubuntu2) fixes the issue for Ubuntu 18.04/Bionic
Following fix was implemented as mentioned by the reporter of the LP bug: https://github.com/linux-pam/linux-pam/commit/c5f829931a22c65feffee16570efdae036524bee

I tested the patch and it indeed resolves the issue: pam_tty_audit now
works as expected and users are still able to login after adding:
session required pam_tty_audit.so enable=root
to
/etc/pam.d/common-session

"aureport --tty" shows the expected output.

  * Fix: pam_tty_audit failed in pam_open_session (LP: #1666203)

The patch has also been submitted to Debian.

The attachment "bionic-fix-for-lp-1666203.debdiff" seems to be a debdiff. The ubuntu-sponsors team has been subscribed to the bug report so that they can review and hopefully sponsor the debdiff. If the attachment isn't a patch, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are member of the ~ubuntu-sponsors, unsubscribe the team.

[This is an automated message performed by a Launchpad user owned by ~brian-murray, for any issue please contact him.]

I am unable to reproduce this issue on Ubuntu 16.04/Xenial with:
libpam-modules 1.1.8-3.2ubuntu2.1
kernel 4.4.0-112-generic

Toru Ikezoe: Could you verify whether this issue still exists on 16.04?

I currently have no plans on testing with Ubuntu 14.04 because of end of support on april 2019.

Thank you for your response.

I tested on 16.04/xenial with below packages, but this issue still exists.
libpam-modules-bin 1.1.8-3.2ubuntu2.1
linux-image-4.4.0-137-generic 4.4.0-137.163

This issue has been fixed on the PAM 1.2.0, but 16.04/xenial and 18.04/bionic used the PAM 1.1.8 and the current package is not include a patche for this issue.

I also tested with commit https://github.com/linux-pam/linux-pam/commit/05a1ccc0df92d0ca031699124ddf7ec3ce12f78f#diff-c5b734a338a8a0460af7f0c08a7b138a which fixes yet another uninitialized use.

Resulting pam_tty_audit.so with both mentioned upstream commits tested and works on bionic, cosmic, and disco.

Thank you both very much for the responses.

Toru: I just tested this on another 16.04 system (now with kernel 4.4.0-142-generic) and was unable to reproduce the issue there also. I was able to reproduce the issue on both Bionic systems I tested however. So there seems to be a difference between Xenial and Bionic.

Patrik: I believe LTS patches are required to be as minimal as possible to minimize regression risk. It appears that the bug is resolved without the change you mentioned. I looked at the code quickly and couldn't determine whether this change is strictly necessary as the variable that is initialized doesn't seem to be used within the module itself. Should you disagree, then please report back.

I would like to ask a sponsor to review the debdiff and give feedback about what changes are desired to get the patch accepted. I will then also test the disco release.

Any feedback or additional information is more than welcome, I'm just trying to move this issue forward as well as I can.

Hello Don, probably an SRU sponsor would like the debdiff to include references where to find the patch that you applied in upstream sources or other bug reports. The usual way to do so is via a Description: and Origin: header in the patch, see https://dep-team.pages.debian.net/deps/dep3/ for more information.

Thanks

Hi Don-san.

I am able to reproduce with the following procedure.

-----------------
vagrant init ubuntu/xenial64
vagrant ssh
# at xenial64 on VM
echo 'session required pam_tty_audit.so enable=*' | sudo tee -a /etc/pam.d/common-session
-----------------

When 'vagrant ssh' from other terminal, it is fail.
I tested below environment.
-----------------
vagrant@ubuntu-xenial:~$ uname -a
Linux ubuntu-xenial 4.4.0-142-generic #168-Ubuntu SMP Wed Jan 16 21:00:45 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
vagrant@ubuntu-xenial:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04.5 LTS
Release: 16.04
Codename: xenial
vagrant@ubuntu-xenial:~$ dpkg -l | grep -E 'libpam|linux-image'
ii libpam-modules:amd64 1.1.8-3.2ubuntu2.1 amd64 Pluggable Authentication Modules for PAM
ii libpam-modules-bin 1.1.8-3.2ubuntu2.1 amd64 Pluggable Authentication Modules for PAM - helper binaries
ii libpam-runtime 1.1.8-3.2ubuntu2.1 all Runtime support for the PAM library
ii libpam-systemd:amd64 229-4ubuntu21.15 amd64 system and service manager - PAM module
ii libpam0g:amd64 1.1.8-3.2ubuntu2.1 amd64 Pluggable Authentication Modules library
ii linux-image-4.4.0-142-generic 4.4.0-142.168 amd64 Linux kernel image for version 4.4.0 on 64 bit x86 SMP
ii linux-image-virtual 4.4.0.142.148 amd64 This package will always depend on the latest minimal generic kernel image.
vagrant@ubuntu-xenial:~$
-----------------

If you cannot reproduce this issue above procedure, you try to enable/disable other pam module.
This problem is caused by an uninitialized stack variable, so it is important to manipulate the state of the stack to reproduce it.
For example, it is good to activate pam_ldap.

Don, I've looked closer at the code and I agree with you.

Thank you all very much for the responses.

I added the description, origin and bug headers to the bionical debdiff, new debdiff is attached.

I was able to reproduce the issue on xenial using vagrant, I will create and test a patch.

Please see attached patch for Ubuntu 16.04/Xenial.
I have tested and verified that the patch works as intended.

This has been fixed for disco with the upload of pam 1.3.1-2ubuntu1.

Thanks Steve!

However, what is the status for Xenial and Bionic?
The bug seems closed now (status: fix released), can someone reopen it?

I have opened bug tasks for the bionic and xenial releases. Your patches are in the queue for the ubuntu-sponsors team to review.

Status changed to 'Confirmed' because the bug affects multiple users.

Don van der Haghen (donvdh),

Seems like you need a sponsor. If I sponsor the patch for you, will you be amenable to test the packages once found in $RELEASE-proposed ?

If cosmic is impacted, could you also please provide a debdiff for it, before I proceed.

Regards,
Eric

and could you please fill the SRU template ?
https://wiki.ubuntu.com/StableReleaseUpdates

I have provided a test package to an impacted user for Bionic/18.04LTS.

Here's what has been brought to my attention after this user tried the test package:
"Test results look good. Keystroke logging audit messages are coming through."

Don,

I'll take care of patching Bionic and Cosmic, and I will let you handle Xenial, if you don't mind through the Ubuntu sponsorship.

I have reviewed your Xenial debdiff, and it will need some rework.
The patch requires to be in quilt (debian/patches-applied), and not file manipulate directly like you did.

- Eric

Uploaded for Bionic and Cosmic.

Hello Toru, or anyone else affected,

Accepted pam into cosmic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/pam/1.1.8-3.6ubuntu3 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 on 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-cosmic to verification-done-cosmic. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-cosmic. In either case, without details of your testing we will not be able to proceed.

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

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

Hello Toru, or anyone else affected,

Accepted pam into bionic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/pam/1.1.8-3.6ubuntu2.18.04.1 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 on 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-bionic to verification-done-bionic. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-bionic. In either case, without details of your testing we will not be able to proceed.

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

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[VERIFICATION BIONIC]
It has been brought to my attention the following (by an impacted user):

I have enabled the "-proposed" pocket and done the following:
1) Logged into workstation, elevated to root
2) Installed packages from "-proposed": libpam0g libpam-modules libpam-modules-bin libpam-runtime
3) Updated /etc/pam.d/common-session and common-session-interactive
4) Started a second session as a regular user and performed a number of console commands, then exited session
5) From the first (root) session, executed "aureport --tty -i".
- The output of the audit report looks good.

If I attempt to perform the same test on another workstation, using the original libpam packages (e.g. skipping step 2) then the test fails at step 4, as the user cannot login. In the logs PAM complains about an invalid parameter on the pam_tty_audit.so line (enable=*).

Sorry for the delay and thanks for the feedback and effort Eric!

Please find the new Xenial debdiff (xenial-fix-for-lp-1666203-v2.debdiff) attached.
I tested the update and verified that it works.

I also tested the Bionic update and verified that it works as intended.

[VERIFICATION COSMIC]

1) Used vagrant init ubuntu/cosmic64 to create new instance.
2) Used vagrant ssh to login.
3) Added "session required pam_tty_audit.so enable=*" at the top of /etc/pam.d/common-session
4) Tried to use in with new vagrant ssh session (package 1.1.8-3.6ubuntu2): DOES NOT WORK/SESSION CLOSES
5) Installed 1.1.8-3.6ubuntu3 from cosmic-proposed
6) Tried to use in with new vagrant ssh session (package 1.1.8-3.6ubuntu3): WORKS
7) Ran "aureport --tty": shows expected output

@Donvdh,

Thanks I'll have a look at it probably next week. Thanks !

This bug was fixed in the package pam - 1.1.8-3.6ubuntu3

---------------
pam (1.1.8-3.6ubuntu3) cosmic; urgency=medium

  * debian/patches-applied/fix-pam_tty_audit.patch: (LP: #1666203)
    Fix pam_tty_audit log_passwd support and regression.

 -- Eric Desrochers <email address hidden> Thu, 28 Feb 2019 01:20:35 +0000

The verification of the Stable Release Update for pam 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.

This bug was fixed in the package pam - 1.1.8-3.6ubuntu2.18.04.1

---------------
pam (1.1.8-3.6ubuntu2.18.04.1) bionic; urgency=medium

  * debian/patches-applied/fix-pam_tty_audit.patch: (LP: #1666203)
    Fix pam_tty_audit log_passwd support and regression.

 -- Eric Desrochers <email address hidden> Wed, 27 Feb 2019 14:26:50 +0000

Uploaded to Xenial.

For future reference, the patches directory goes inside debian/

Thanks!

Hello Toru, or anyone else affected,

Accepted pam into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/pam/1.1.8-3.2ubuntu2.2 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 on 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-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. 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!

Thanks!

[VERIFICATION XENIAL]

1) Used vagrant init ubuntu/xenial64 to create new instance.
2) Used vagrant ssh to login.
3) Added "session required pam_tty_audit.so enable=*" at the top of /etc/pam.d/common-session
5) Installed 1.1.8-3.2ubuntu2.2 from xenial-proposed
6) Tried to use in with new vagrant ssh session: WORKS
7) Ran "aureport --tty": shows expected output

@Toru: Could you verify this also?

Hi Don-san.

I tried test, but it not fixed.
I tried building by source code of version 1.1.8-3.2ubuntu 2.2, it looks like the patch has not been applied.
Can you check again?

[VERIFICATION XENIAL]

1) Used vagrant init ubuntu/xenial64 to create new instance.
2) Used vagrant ssh to login.
3) Added "session required pam_tty_audit.so enable=*" at the top of /etc/pam.d/common-session
4) Tried to use in with new vagrant ssh session (package 1.1.8-3.2ubuntu2.1): DOES NOT WORK/SESSION CLOSES
5) Installed 1.1.8-3.2ubuntu2.2 from xenial-proposed
6) Tried to use in with new vagrant ssh session: DOES NOT WORK/SESSION CLOSES

All autopkgtests for the newly accepted pam (1.1.8-3.2ubuntu2.2) for xenial have finished running.
The following regressions have been reported in tests triggered by the package:

systemd/229-4ubuntu21.21 (s390x)

Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-migration/xenial/update_excuses.html#pam

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

Hello!

Thanks for your work with creating and testing the patch.
When Xenial Fix will be released?

I'd love to see it, because activation of Proposed repo on dozens hosts does not looks very good.
Thanks!

@David have you tested the version of the package in -proposed and does it work for you? If so could you please provide testing details so that we can release the package.

The version of pam in the proposed pocket of Xenial that was purported to fix this bug report has been removed because the bugs that were to be fixed by the upload were not verified in a timely (105 days) fashion.

Hello Toru, or anyone else affected,

Accepted pam into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/pam/1.1.8-3.2ubuntu2.3 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 on 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, what testing has been performed on the package and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, without details of your testing we will not be able to proceed.

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

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

All autopkgtests for the newly accepted pam (1.1.8-3.2ubuntu2.3) for xenial have finished running.
The following regressions have been reported in tests triggered by the package:

systemd/229-4ubuntu21.29 (amd64, i386)
kscreenlocker/5.5.5-0ubuntu1 (armhf)

Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-migration/xenial/update_excuses.html#pam

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

Verified the new upload on xenial:

root@xenial-pam-play:~# dpkg -l libpam-modules
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-============================================-===========================-===========================-==============================================================================================
ii libpam-modules:amd64 1.1.8-3.2ubuntu2.1 amd64 Pluggable Authentication Modules for PAM
root@xenial-pam-play:~# sudo -u ubuntu bash
sudo: policy plugin failed session initialization
root@xenial-pam-play:~# apt install libpam-modules/xenial-proposed libpam-modules-bin/xenial-proposed
Reading package lists... Done
Building dependency tree
Reading state information... Done
Selected version '1.1.8-3.2ubuntu2.3' (Ubuntu:16.04/xenial-proposed [amd64]) for 'libpam-modules'
Selected version '1.1.8-3.2ubuntu2.3' (Ubuntu:16.04/xenial-proposed [amd64]) for 'libpam-modules-bin'
Recommended packages:
  update-motd
The following packages will be upgraded:
  libpam-modules libpam-modules-bin
2 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 281 kB of archives.
After this operation, 0 B of additional disk space will be used.
Get:1 http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 libpam-modules-bin amd64 1.1.8-3.2ubuntu2.3 [36.9 kB]
Get:2 http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 libpam-modules amd64 1.1.8-3.2ubuntu2.3 [244 kB]
Fetched 281 kB in 2s (111 kB/s)
Preconfiguring packages ...
(Reading database ... 47120 files and directories currently installed.)
Preparing to unpack .../libpam-modules-bin_1.1.8-3.2ubuntu2.3_amd64.deb ...
Unpacking libpam-modules-bin (1.1.8-3.2ubuntu2.3) over (1.1.8-3.2ubuntu2.1) ...
Setting up libpam-modules-bin (1.1.8-3.2ubuntu2.3) ...
(Reading database ... 47120 files and directories currently installed.)
Preparing to unpack .../libpam-modules_1.1.8-3.2ubuntu2.3_amd64.deb ...
Unpacking libpam-modules:amd64 (1.1.8-3.2ubuntu2.3) over (1.1.8-3.2ubuntu2.1) ...
Setting up libpam-modules:amd64 (1.1.8-3.2ubuntu2.3) ...
root@xenial-pam-play:~# sudo -u ubuntu bash
To run a command as administrator (user "root"), use "sudo <command>".
See "man sudo_root" for details.

bash: /root/.bashrc: Permission denied
ubuntu@xenial-pam-play:~$ ls
ls: cannot open directory '.': Permission denied
ubuntu@xenial-pam-play:~$ exit
root@xenial-pam-play:~# aureport --tty -i

TTY Report
===============================================
# date time event auid term sess comm data
===============================================
1. 10/01/20 08:21:14 132 unset ? 4294967295 bash "ls",<ret>,<^D>

This bug was fixed in the package pam - 1.1.8-3.2ubuntu2.3

---------------
pam (1.1.8-3.2ubuntu2.3) xenial; urgency=medium

  * Move patch fixing LP: #1666203 from debian/patches to
    debian/patches-applied so it actually gets applied.
  * debian/libpam-modules.postinst: Add /snap/bin to $PATH in
    /etc/environment. (LP: #1659719)

pam (1.1.8-3.2ubuntu2.2) xenial; urgency=medium

  * Fix: pam_tty_audit failed in pam_open_session (LP: #1666203)

 -- Michael Hudson-Doyle <email address hidden> Thu, 01 Oct 2020 10:03:21 +1300