[Bug 1677329] Re: libpam-winbind: unable to dlopen

Andreas Hasenack andreas at canonical.com
Wed Jun 21 13:45:25 UTC 2017


** Description changed:

  [Impact]
  
  The pam_winbind.so module is unusable in zesty. It won't load because of
  missing symbols:
  
  Jun 21 13:17:05 zesty-pamwinbind-1677329 systemd: PAM unable to
  dlopen(pam_winbind.so): /lib/security/pam_winbind.so: cannot open shared
  object file: No such file or directory
  
  This is due to the (re)introduction of patch fix-1584485.patch which
  changes the way this module is built, trying to statically link some
  libraries. That linking was incorrectly done.
  
  The patch was subsequently removed, but later added back again by
- mistake during a huge sync.
+ mistake during a sync.
  
- A new version of the patch exists, but upstream (Samba) isn't very fond
- of such a change and asked to submit it for discussion to the samba-
- technical mailing list.
+ A new version of the patch exists
+ (https://code.launchpad.net/~ahasenack/ubuntu/+source/samba/+git/samba/+merge/323767),
+ but upstream (Samba and Debian) isn't very fond of such a change and
+ asked me to submit it for discussion to the samba-technical mailing list
+ (https://lists.samba.org/archive/samba-technical/2017-June/121139.html).
  
  That was done, but since this could take some time, we decided it's best
- to revert the patch one more time.
+ to revert the patch again.
  
  [Test Case]
  
  In a zesty machine/container:
-  * sudo apt install libpam-winbind winbind samba
-  * tail -f /var/log/auth.log
-  * perform a login on this machine. Via ssh, for example
-  * the broken version will log this:
+  * sudo apt install libpam-winbind winbind samba
+  * tail -f /var/log/auth.log
+  * perform a login on this machine. Via ssh, for example
+  * the broken version will log this:
  Jun 21 13:17:05 zesty-pamwinbind-1677329 systemd: PAM unable to dlopen(pam_winbind.so): /lib/security/pam_winbind.so: cannot open shared object file: No such file or directory
-  * The fixed version will load winbind just fine, but won't log anything (unless you fully setup winbind). It's easier to add "debug" to the pam_winbind.so lines in /etc/pam.d/common-* files and repeat the login, then you get to see it being loaded in the logs
+  * The fixed version will load pam_winbind.so just fine, but won't log anything (unless you fully setup winbind). It's easier to add "debug" to the pam_winbind.so lines in /etc/pam.d/common-* files and repeat the login, then you get to see it being loaded in the logs.
  
  [Regression Potential]
  
  This reversal has been done before and worked. Right now, the biggest
  regression potential is to add the broken patch back again.
  
+ Reversing this patch will also reintroduce bug #1584485, but I think the
+ configuration that leads to that bug is asking for trouble and I stated
+ as such in a comment
+ (https://bugs.launchpad.net/ubuntu/+source/samba/+bug/1584485/comments/43).
+ "winbind" should be listed after "files" or "compat", not before.
+ 
+ That being said, it is my opinion that having a working pam_winbind
+ module benefits more users than the amount of users that could be
+ affected by the particular configuration that leads to #1584485.
+ 
  [Other Info]
- Sorry for keeping both bugs open (#1644428 and #1677329), but the history on this issue is a bit complicated with multiple SRUs and regressions.
+ 
+ Sorry for keeping both bugs open (#1644428 and #1677329), but the
+ history on this issue is a bit complicated with multiple SRUs and
+ regressions.

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https://bugs.launchpad.net/bugs/1677329

Title:
  libpam-winbind: unable to dlopen

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