The documentation for pam_open_session says, "It should be noted that the effective uid, geteuid(2). of the application should be of sufficient privilege to perform such tasks as creating or mounting the user's home directory for example."
AFAICT, this is contrary to Steve Langasek's assertion that "Session modules are normally invoked after the application has changed uids to that of the target user." If lightdm has already dropped privileges at this point, I think it's a bug. -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to lightdm in Ubuntu. https://bugs.launchpad.net/bugs/956848 Title: pam_mkhomedir.so fails to create homedir in precise Status in Light Display Manager: New Status in “lightdm” package in Ubuntu: Confirmed Bug description: I am testing Ubuntu Precise and I think I found a bug related to creation of home directories with pam_mkhomedir.so. I found it initially in an LDAP-based setup, but to nail down the problem I did a fresh re-install, added: session optional pam_mkhomedir.so umask=0077 skel=/etc/skel to /etc/pam.d/common-session and I removed the home directory of the user used during installation, so the bug has nothing to do with network auth. Anyway - when I login to lightdm I am successfully authenticated and the logon screen disappears, but I am presented with a black screen and nothing happens. I can login from text mode, the homedir is created and afterwards I can login, even using the graphical interface. I tried to see if this is related to lightdm or unity, but if I select Gnome classic, I get the same problem, if I switch to GDM, the problem remains. I am attaching the logs from lightdm. The syslog says: Mar 16 10:31:45 tubuntu kernel: [99829.342230] accounts-daemon[2152]: segfault at 10 ip b76c86c3 sp bfab7640 error 4 in libdbus-1.so.3.5.8[b76a3000+47000] Mar 16 10:31:45 tubuntu kernel: [99829.342545] gdm-session-wor[29440]: segfault at 6e756279 ip b743cd4c sp bf84b250 error 4 in libc-2.15.so[b73ca000+19e000] but I cannot say if this caused the issue or was caused by the issue. I hope somebody can have a look at this. I can help to do some investigating, unfortunately I don't know where to look. To manage notifications about this bug go to: https://bugs.launchpad.net/lightdm/+bug/956848/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp