Hi, I'm having problems using libpam-heimdal (Kerberos v5) with xdm under Debian (Sarge). I've tracked down the problem precisely, and I am proposing a specific fix; this isn't a cry for help.
The symptom is the following. If the file /etc/pam.d/xdm contains the line auth sufficient pam_krb5.so debug at the top, the function "pam_setcred" is called twice by xdm, first in the function Verify at about line 500 in the file xc/programs/xdm/greeter/verify.c then again in the function StartClient at about line 596 in the file xc/programs/xdm/session.c What happens is that the function pam_sm_setcred in libpam-heimdal-1.0/pam_krb5_auth.c checks to see if a Kerberos credentials cache already exists, and if it does the function fails. Since it is called twice, the credentials cache is created by the first call, then the second call causes pam_sm_setcred to fail, and with it the login fails. It turns out that this behavior (checking for the existence of a credentials cache in pam_sm_setcred and failing if it exists) is added by a Debian patch, namely the last hunk of "destroy-ticket.patch" that comes with libpam-heimdal. If I build libpam-heimdal without this hunk, then everything works fine. In addition, after logging in with xdm, the credentials cache contains the TGT and host tickets I expect. So we should either remove this hunk from libpam-heimdal so that it doesn't care if the ccache exists already, or xdm should not call pam_setcred twice (once for authentication and once for session). Chip -- Charles M. "Chip" Coldwell System Administrator Harvard Physics Department 617-495-3388
