Discussion:
[Bug 1771434] [NEW] Log Out/login does not recognize new supplementary group; Hangs after repeated Log Out/login cycles
jimav
2018-05-15 21:22:02 UTC
Permalink
Public bug reported:

If a supplementary group is added to a user who is currently logged in
to a graphical session, then strange breakage occurs:

Problem #1: If the changed user logs out and then logs in again,
  their processes still do not have the new group membership.

  It seems necessary to reboot for the group add to take effect in
  graphically logins. However "su - <user>" in a terminal does get a
  process with tne new group.

Problem #2: If the changed user repeatedly does "Log Out" and then
  logs in again via gdm, eventually "Log Out" stops working
  completely (invoking it has no discernible effect).

STEPS TO REPRODUCE:

1. Log in graphically as any existing user (might not be relevant).

2. Control-Alt-F3 to get a vt login; log in as root.

   In the root shell:
     adduser testuser
     (enter a password)
     (hit ENTER to take defaults for all other prompts)

3. Alt-Ctrl-F1 to get to the grpahical login
   Log in as "testuser"

4. Control-Alt-F3 to return to the root shell.

     usermod -a -G sudo testuser # group 'sudo' is an example

5. Alt-Ctrl-F1 to get to the grpahical login
   Return to session of user "testuser"

   Upper-right-corner-menu->testuser->Log Out
   (returns to graphical login selector)

6. Log in as "testuser" again
   Start a gnome-terminal and type "id<Enter>"

RESULTS: "id" shows that the process does NOT
  have "sudo" as a supplementary group.

EXPECTED RESULTS: New graphical logins should see credential changes.

7. Repeatedly do
     Upper-right-corner-menu->testuser->Log Out
     Log in again as "testuser"

RESULTS: After 3 or 4 iterations, "Log Out" stops working altogether.

(When finished "deluser --remove-home testuser" to clean up)

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gdm3 3.28.0-0ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-20.21-generic 4.15.17
Uname: Linux 4.15.0-20-generic x86_64
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Tue May 15 14:17:25 2018
InstallationDate: Installed on 2018-04-05 (40 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Beta amd64 (20180403.1)
SourcePackage: gdm3
UpgradeStatus: No upgrade log present (probably fresh install)

** Affects: gdm3 (Ubuntu)
Importance: Undecided
Status: New


** Tags: amd64 apport-bug bionic

** Summary changed:

- Log Out/login does not recognize new supplementary group; Lot Out hangs eventually
+ Log Out/login does not recognize new supplementary group; Hangs after repeated Log Out/login cycles

** Description changed:

If a supplementary group is added to a user who is currently logged in
to a graphical session, then strange breakage occurs:

Problem #1: If the changed user logs out and then logs in again,
- their processes still do not have the new group membership.
+   their processes still do not have the new group membership.

- It seems necessary to reboot for the group add to take effect in
- in graphically logins.
+   It seems necessary to reboot for the group add to take effect in
+   graphically logins. However "su - <user>" in a terminal does get a
+ process with tne new group.

Problem #2: If the changed user repeatedly does "Log Out" and then
- logs in again via gdm, eventually "Log Out" stops working
- completely (invoking it has no discernible effect).
+   logs in again via gdm, eventually "Log Out" stops working
+   completely (invoking it has no discernible effect).

STEPS TO REPRODUCE:

1. Log in graphically as any existing user (might not be relevant).

2. Control-Alt-F3 to get a vt login; log in as root.

- In the root shell:
- adduser testuser
- (enter a password)
- (hit ENTER to take defaults for all other prompts)
+    In the root shell:
+      adduser testuser
+      (enter a password)
+      (hit ENTER to take defaults for all other prompts)

- 3. Alt-Ctrl-F1 to get to the grpahical login
- Log in as "testuser"
+ 3. Alt-Ctrl-F1 to get to the grpahical login
+    Log in as "testuser"

4. Control-Alt-F3 to return to the root shell.

- usermod -a -G sudo testuser # group 'sudo' is an example
+      usermod -a -G sudo testuser # group 'sudo' is an example

5. Alt-Ctrl-F1 to get to the grpahical login
- Return to session of user "testuser"
+    Return to session of user "testuser"

- Upper-right-corner-menu->testuser->Log Out
- (returns to graphical login selector)
+    Upper-right-corner-menu->testuser->Log Out
+    (returns to graphical login selector)

6. Log in as "testuser" again
- Start a gnome-terminal and type "id<Enter>"
+    Start a gnome-terminal and type "id<Enter>"

RESULTS: "id" shows that the process does NOT
- have "sudo" as a supplementary group.
+   have "sudo" as a supplementary group.

EXPECTED RESULTS: New graphical logins should see credential changes.

7. Repeatedly do
- Upper-right-corner-menu->testuser->Log Out
- Log in again as "testuser"
+      Upper-right-corner-menu->testuser->Log Out
+      Log in again as "testuser"

RESULTS: After 3 or 4 iterations, "Log Out" stops working altogether.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gdm3 3.28.0-0ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-20.21-generic 4.15.17
Uname: Linux 4.15.0-20-generic x86_64
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Tue May 15 14:17:25 2018
InstallationDate: Installed on 2018-04-05 (40 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Beta amd64 (20180403.1)
SourcePackage: gdm3
UpgradeStatus: No upgrade log present (probably fresh install)

** Description changed:

If a supplementary group is added to a user who is currently logged in
to a graphical session, then strange breakage occurs:

Problem #1: If the changed user logs out and then logs in again,
  their processes still do not have the new group membership.

  It seems necessary to reboot for the group add to take effect in
  graphically logins. However "su - <user>" in a terminal does get a
- process with tne new group.
+   process with tne new group.

Problem #2: If the changed user repeatedly does "Log Out" and then
  logs in again via gdm, eventually "Log Out" stops working
  completely (invoking it has no discernible effect).

STEPS TO REPRODUCE:

1. Log in graphically as any existing user (might not be relevant).

2. Control-Alt-F3 to get a vt login; log in as root.

   In the root shell:
     adduser testuser
     (enter a password)
     (hit ENTER to take defaults for all other prompts)

3. Alt-Ctrl-F1 to get to the grpahical login
   Log in as "testuser"

4. Control-Alt-F3 to return to the root shell.

     usermod -a -G sudo testuser # group 'sudo' is an example

5. Alt-Ctrl-F1 to get to the grpahical login
   Return to session of user "testuser"

   Upper-right-corner-menu->testuser->Log Out
   (returns to graphical login selector)

6. Log in as "testuser" again
   Start a gnome-terminal and type "id<Enter>"

RESULTS: "id" shows that the process does NOT
  have "sudo" as a supplementary group.

EXPECTED RESULTS: New graphical logins should see credential changes.

7. Repeatedly do
     Upper-right-corner-menu->testuser->Log Out
     Log in again as "testuser"

RESULTS: After 3 or 4 iterations, "Log Out" stops working altogether.

+ (When finished "deluser --remove-home testuser" to clean up)
+
ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gdm3 3.28.0-0ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-20.21-generic 4.15.17
Uname: Linux 4.15.0-20-generic x86_64
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Tue May 15 14:17:25 2018
InstallationDate: Installed on 2018-04-05 (40 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Beta amd64 (20180403.1)
SourcePackage: gdm3
UpgradeStatus: No upgrade log present (probably fresh install)
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https://bugs.launchpad.net/bugs/1771434

Title:
Log Out/login does not recognize new supplementary group; Hangs after
repeated Log Out/login cycles

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Daniel van Vugt
2018-05-16 04:19:51 UTC
Permalink
You seem to be reporting two separate bugs.

Please reword this one so as to move the other into a new bug report.

** Changed in: gdm3 (Ubuntu)
Status: New => Incomplete
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https://bugs.launchpad.net/bugs/1771434

Title:
Log Out/login does not recognize new supplementary group; Hangs after
repeated Log Out/login cycles

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/gdm3/+bug/1771434/+subscriptions
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