Autofs cifs mounts via Kerberos

Autofs cifs mounts via Kerberos

[Carter, Joel]

Hi there.

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@DOMAIN.CA
        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 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.

Any help is much appreciated, I'm almost there!

Joel.

Re: Autofs cifs mounts via Kerberos

[Ian Kent]

On Mon, 2010-12-06 at 12:41 -0800, Carter, Joel wrote:
> Hi there.
> 
> 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.

Yeah, this is probably the wrong place for this since it may be more to
do with cifs than autofs.

I would say log a Bugzilla bug against RHEL CIFS but, strictly speaking,
you should go via GSS support, as GSS are the group that sanity check,
gather initial information, and monitor escalations for fixes that
customers need.

But logging a Bugzilla bug may get some information reasonably quickly
if you can get some attention.

> 
> 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@DOMAIN.CA
>         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 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.
> 
> Any help is much appreciated, I'm almost there!
> 
> Joel.
> 
> _______________________________________________
> autofs mailing list
> autofs@linux.kernel.org
> http://linux.kernel.org/mailman/listinfo/autofs

Autofs cifs mounts via Kerberos

[Carter, Joel]

Hi there.

Note - cross-posted to autofs-CPWUtch7KCBzeIdxy0IIJw@public.gmane.org

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-Cx6ELD3zwl23NexWsGEg3A@public.gmane.org
        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
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.

Any help is much appreciated, I'm almost there!

Joel.


 
Joel Carter 
Senior Systems Administrator
, , 
Direct: (604) 320-7624   Cell: (604) 328-0672   Branch: (604) 320-7624
Toll Free:    Fax:   
trailerwizards.com

Re: Autofs cifs mounts via Kerberos

[Jeff Layton]

On Mon, 6 Dec 2010 14:00:28 -0800
"Carter, Joel" <JoelC-RAygmcqizRRkKYb1c3iuxNBPR1lH4CV8@public.gmane.org> wrote:

> Hi there.
> 
> Note - cross-posted to autofs-CPWUtch7KCBzeIdxy0IIJw@public.gmane.org
> 
> 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-Cx6ELD3zwl23NexWsGEg3A@public.gmane.org
>         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-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

RE: Autofs cifs mounts via Kerberos

[Carter, Joel]

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-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org] 
Sent: December-07-10 5:13 AM
To: Carter, Joel
Cc: linux-cifs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: Autofs cifs mounts via Kerberos

On Mon, 6 Dec 2010 14:00:28 -0800
"Carter, Joel" <JoelC-RAygmcqizRRkKYb1c3iuxNBPR1lH4CV8@public.gmane.org> wrote:

> Hi there.
> 
> Note - cross-posted to autofs-CPWUtch7KCBzeIdxy0IIJw@public.gmane.org
> 
> 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-Cx6ELD3zwl23NexWsGEg3A@public.gmane.org
>         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-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

Re: Autofs cifs mounts via Kerberos

[Steve French]

On Tue, Dec 7, 2010 at 11:03 AM, Carter, Joel <JoelC-RAygmcqizRRkKYb1c3iuxNBPR1lH4CV8@public.gmane.org> wrote:
> 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.

smbfs doesn't support krb5.

I did get the impression that Jeff did a good job of the Kerberos
backport for RHEL5 though.

-- 
Thanks,

Steve

Re: Autofs cifs mounts via Kerberos

[Jeff Layton]

On Tue, 7 Dec 2010 11:11:08 -0600
Steve French <smfrench-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> On Tue, Dec 7, 2010 at 11:03 AM, Carter, Joel <JoelC-RAygmcqizRRkKYb1c3iuxNBPR1lH4CV8@public.gmane.org> wrote:
> > 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.
> 
> smbfs doesn't support krb5.
> 

Actually, I think it does. Socket creation and setup in smbfs was
essentially offloaded to userspace so as long as libsmbclient supported
it, it did too. I never really messed with it though so I can't vouch
for its robustness.

The point is moot though since RHEL5 didn't ship with smbfs enabled.

> I did get the impression that Jeff did a good job of the Kerberos
> backport for RHEL5 though.
> 

Thanks, it basically works. There are some differences between how
RHEL5 and RHEL6/mainline handle the uid= option however.

-- 
Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>