Hi Jeff. Yes I think you are right that it's race condition between the Kerberos ticket being stored and the automounter attempting to use that ticket. Thanks for the reminder of sec=krb5 maturity status, I wasn't aware of that. This is for a production system so I should probably stay away from it. That said, do you know if this is possible with RHEL5 using smbfs (sorry - off topic) or should I push this off until we move to RHEL6? It's not a must have, just trying to make our AD/RHEL integration as tight as possible. I found your bugzilla entry as well, I'll keep my eyes on it. Thanks, Joel. -----Original Message----- From: Jeff Layton [mailto:jlayton@xxxxxxxxxx] Sent: December-07-10 5:13 AM To: Carter, Joel Cc: linux-cifs@xxxxxxxxxxxxxxx Subject: Re: Autofs cifs mounts via Kerberos On Mon, 6 Dec 2010 14:00:28 -0800 "Carter, Joel" <JoelC@xxxxxxxxxxxxxxxxxx> wrote: > Hi there. > > Note - cross-posted to autofs@xxxxxxxxxxxxxxxx > > I am putting the finishing touches on our AD/LDAP using autofs to mount > home directories on a Red Hat 5 box. I have login authentication working > great, using both traditional SSH authentication (Linux does > authentication) and GSSAPI (passes Kerberos tickets directly) for > single-sign-on. The problem is mounting the home directories. If this is > the wrong list for this integration stuff let me know if you know of a > better candidate. > > Here's my configuration: > > auto.master: > /home_cifs /etc/auto.cifs --timeout=5 > > auto.cifs: > * > -fstype=cifs,sec=krb5,user=&,uid=&,gid=lgtr,file_mode=0644,dir_mode=0755 > ://smb.domain.local/userdata/& > > /etc/request-key.conf: > ... > create cifs.spnego * * /usr/sbin/cifs.upcall %k create dns_resolver * > * /usr/sbin/cifs.upcall %k > > /etc/pam.d/system-auth-ac: > #%PAM-1.0 > # This file is auto-generated. > # User changes will be destroyed the next time authconfig is run. > auth required pam_env.so > auth sufficient pam_unix.so nullok try_first_pass > auth sufficient pam_krb5.so > auth requisite pam_succeed_if.so uid >= 500 quiet > auth required pam_deny.so > > account required pam_unix.so > account sufficient pam_succeed_if.so uid < 500 quiet > account sufficient pam_krb5.so > account required pam_permit.so > > password requisite pam_cracklib.so try_first_pass retry=3 > password sufficient pam_unix.so md5 shadow nullok try_first_pass > use_authtok > password required pam_deny.so > > session optional pam_keyinit.so revoke > session required pam_limits.so > session [success=1 default=ignore] pam_succeed_if.so service in > crond quiet use_uid > session required pam_unix.so > > /etc/pam.d/sshd > #%PAM-1.0 > auth include system-auth > account required pam_nologin.so > account include system-auth > password include system-auth > session optional pam_keyinit.so force revoke > session include system-auth > session required pam_loginuid.so > > Every user has their unixHomeDirectory set to /home_cifs/<username> > > The mount doesn't seem to work on login but autofs is working. It works > fine once logged in (most of the time but does fail sometimes as well) > and I change the directory to the home: > > Dec 6 11:57:37 bilbo-rh5 cifs.upcall: key description: > cifs.spnego;0;0;3f000000;ver=0x2;host=smb.domain.local;ip4=192.168.1.58; > sec=mskrb5;uid=0x4e20;user=lguser > Dec 6 11:57:37 bilbo-rh5 cifs.upcall: find_krb5_cc: considering > /tmp/krb5cc_20000_BfIUPW5852 Dec 6 11:57:37 bilbo-rh5 cifs.upcall: > find_krb5_cc: FILE:/tmp/krb5cc_20000_BfIUPW5852 is valid ccache Dec 6 > 11:57:37 bilbo-rh5 cifs.upcall: handle_krb5_mech: getting service ticket > for cifs/smb.domain.local Dec 6 11:57:37 bilbo-rh5 cifs.upcall: > handle_krb5_mech: obtained service ticket Dec 6 11:57:37 bilbo-rh5 > automount[5642]: mount(generic): mounted > //smb.domain.local/userdata/lguser type cifs on /home_cifs/lguser Dec 6 > 11:57:37 bilbo-rh5 automount[5642]: mounted /home_cifs/lguser > > Klist shows this: > 12/06/10 12:06:55 12/06/10 21:17:32 cifs/smb.domain.local@xxxxxxxxx > renew until 12/06/10 22:06:55 > > Then I can login without problem until automount expires the mount. When > it doesn't work this is what is shown: > > Dec 6 11:59:09 bilbo-rh5 cifs.upcall: key description: > cifs.spnego;0;0;3f000000;ver=0x2;host=smb.domain.local;ip4=192.168.1.58; > sec=mskrb5;uid=0x4e20;user=lguser > Dec 6 11:59:09 bilbo-rh5 cifs.upcall: handle_krb5_mech: getting service > ticket for cifs/smb.domain.local Dec 6 11:59:09 bilbo-rh5 cifs.upcall: > handle_krb5_mech: failed to obtain service ticket (-1765328189) Dec 6 > 11:59:09 bilbo-rh5 cifs.upcall: handle_krb5_mech: getting service ticket > for host/smb.domain.local Dec 6 11:59:09 bilbo-rh5 cifs.upcall: > handle_krb5_mech: failed to obtain service ticket (-1765328189) Dec 6 $ grep 1765328189 /usr/include/krb5/krb5.h #define KRB5_FCC_NOFILE (-1765328189L) ...which means that cifs.upcall couldn't find the credential cache for that UID (20000). Yes, it would be nice to pretty-print that error, but I'm not sure what kerberos function does that. > 11:59:09 bilbo-rh5 kernel: CIFS VFS: cifs_mount failed w/return code = > -126 Dec 6 11:59:09 bilbo-rh5 automount[5642]: >> Refer to the > mount.cifs(8) manual page (e.g. man mount.cifs) Dec 6 11:59:09 > bilbo-rh5 automount[5642]: mount(generic): failed to mount > //smb.domain.local/userdata/lguser (type cifs) on /home_cifs/lguser Dec > 6 11:59:09 bilbo-rh5 automount[5642]: failed to mount /home_cifs/lguser > > I have wireshark traces as well for success and non-success. > I doubt that'll tell you much. I think the problem is with kerberos. Maybe you have a race condition between the creation of the credential cache and the automount being triggered? That's probably where I'd focus my efforts... For an FYI, the sec=krb5 code is still "tech-preview" in RHEL5. There are some differences between the implementation there and the one in RHEL6. I'm hoping to get multiuser mounts into RHEL6.1, which will mean that you can do away with autofs here and just mount "userdata" on "/home_cifs" in this configuration. Each user will be able to use their own credentials when accessing the mount. That should be a lot simpler and less "fiddly" than autofs for this configuration. -- Jeff Layton <jlayton@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
