dx-packages team mailing list archive

[Grzegorz Gutowski <1314095@xxxxxxxxxxxxxxxxxx>]

When I add suid root to unix_chkpwd binary:

chmod u+s /sbin/unix_chkpwd

then everything works as expected: both lightdm and unity lockscreen are
accepting my password.

Without suid it seems that call (with correct username) to getspnam in function get_account_info in file passverify.c in pam/modules/pam_unix returns NULL. I don't understand this behaviour. I wrote a simple c program that calls getspnam and it works as expected when called from unprivileged user.
When unix_chkpwd (both suid root and not) is called by lightdm, then it always works good.

-- 
You received this bug notification because you are a member of DX
Packages, which is subscribed to unity in Ubuntu.
Matching subscriptions: dx-packages
https://bugs.launchpad.net/bugs/1314095

Title:
  Unity Lockscreen in 14.04 can't unlock when using LDAP account

Status in “unity” package in Ubuntu:
  Confirmed

Bug description:
  My setup is:

  Ubuntu 14.04 LTS,
  ldap accounts,
  krb5 authentication,
  Lightdm,
  Unity session

  ldap+krb5 is configured using nss-ldapd and nslcd. It works fine. getent passwd and getent shadow works fine.
  I am able to login in console without any problems.
  I was able to login in lightdm.
  Then I used the lock screen.
  I could not disable the lock screen using my password.
  I rebooted my computer.

  Now:
  After logging in through lightdm, the unity lockscreen locks the screen immediately and I can not disable it using my password.

  From my short inspection of auth.log and unix_chkpwd sources it seems,
  that unix_chkpwd works fine when called from lightdm and fails to get
  user info when called from unity lockscreen.


  lsb_release -rd
  Description:	Ubuntu 14.04 LTS
  Release:	14.04

  apt-cache policy unity lightdm libpam-modules
  unity:
    Installed: 7.2.0+14.04.20140416-0ubuntu1
    Candidate: 7.2.0+14.04.20140416-0ubuntu1
    Version table:
   *** 7.2.0+14.04.20140416-0ubuntu1 0
          500 http://archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages
          100 /var/lib/dpkg/status
  lightdm:
    Installed: 1.10.0-0ubuntu3
    Candidate: 1.10.0-0ubuntu3
    Version table:
   *** 1.10.0-0ubuntu3 0
          500 http://archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages
          100 /var/lib/dpkg/status
  libpam-modules:
    Installed: 1.1.8-1ubuntu2
    Candidate: 1.1.8-1ubuntu2
    Version table:
   *** 1.1.8-1ubuntu2 0
          500 http://archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages
          100 /var/lib/dpkg/status

  Contents of /var/log/auth.log:

  Apr 29 06:49:27 localhost lightdm: pam_succeed_if(lightdm:auth): requirement "user ingroup nopasswdlogin" not met by user "user"
  Apr 29 06:49:31 localhost lightdm: pam_unix(lightdm:auth): authentication failure; logname= uid=0 euid=0 tty=:2 ruser= rhost=  user=user
  Apr 29 06:49:31 localhost lightdm: pam_krb5(lightdm:auth): user user authenticated as user@NETWORK
  Apr 29 06:49:32 localhost lightdm[15604]: pam_unix(lightdm-greeter:session): session closed for user lightdm
  Apr 29 06:49:37 localhost unix_chkpwd[15825]: check pass; user unknown
  Apr 29 06:49:37 localhost unix_chkpwd[15825]: password check failed for user (user)
  Apr 29 06:49:37 localhost compiz: pam_unix(lightdm:auth): authentication failure; logname= uid=1001 euid=1001 tty= ruser= rhost=  user=user
  Apr 29 06:49:37 localhost compiz: pam_krb5(lightdm:auth): user user authenticated as user@NETWORK
  Apr 29 06:49:37 localhost unix_chkpwd[15826]: could not obtain user info (user)
  Apr 29 06:49:37 localhost unix_chkpwd[15827]: could not obtain user info (user)
  Apr 29 06:49:37 localhost compiz: pam_succeed_if(lightdm:auth): requirement "user ingroup nopasswdlogin" not met by user "user"

  cat /etc/pam.d/common-auth 
  account     required    pam_unix.so
  auth        required    pam_group.so
  auth [success=2 default=ignore] pam_unix.so try_first_pass nullok_secure
  auth [success=1 default=ignore] pam_krb5.so try_first_pass minimum_uid=200
  auth        requisite   pam_deny.so
  auth        required    pam_permit.so

  auth        optional    pam_afs_session.so minimum_uid=200
  auth        optional    pam_ecryptfs.so unwrap
  auth        optional    pam_cap.so

  cat /etc/pam.d/common-account 
  account     required    pam_unix.so

  cat /etc/pam.d/lightdm
  auth        requisite   pam_nologin.so
  auth        sufficient  pam_succeed_if.so user ingroup nopasswdlogin
  @include common-auth
  auth        optional    pam_gnome_keyring.so
  @include common-account
  session [success=ok ignore=ignore module_unknown=ignore default=bad] pam_selinux.so close
  auth        optional    pam_group.so
  session     required    pam_limits.so
  @include common-session
  session [success=ok ignore=ignore module_unknown=ignore default=bad] pam_selinux.so open
  session     optional    pam_gnome_keyring.so auto_start
  session     required    pam_env.so readenv=1
  session     required    pam_env.so readenv=1 user_readenv=1 envfile=/etc/default/locale
  @include common-password

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/unity/+bug/1314095/+subscriptions