[Bug 794112] Re: Kerberos + LDAP + NFSv4 - Unable to recover unattended client

Launchpad Bug Tracker 794112 at bugs.launchpad.net
Fri Sep 28 18:44:38 UTC 2012


** Branch linked: lp:ubuntu/nfs-utils

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https://bugs.launchpad.net/bugs/794112

Title:
  Kerberos + LDAP + NFSv4 - Unable to recover unattended client

Status in Network Authentication System:
  New
Status in NFS-Utils - NFS support files common to client and server:
  New
Status in “nfs-utils” package in Ubuntu:
  Fix Released
Status in “nfs-utils” source package in Precise:
  In Progress
Status in “nfs-utils” package in Debian:
  New

Bug description:
  [Impact]
  Those who heavily rely on kerberized mounted home directories

  
  [Test Case]
  Hi there!

  I've configured a Natty client/server pair to authenticate over
  Kerberos and LDAP and to mount user home directories via NFSv4 with
  sec=krb5. I am using a slight variation on the configuration described
  here: http://www.danbishop.org/2011/05/01/ubuntu-11-04-sbs-small-
  business-server-setup-part-3-openldap/

  Under this setup, user sessions that are left unattended for a long
  period of time -- eg, when someone goes home for the night but stays
  logged in -- always result in a wedged machine. What do I mean by
  "wedged?" When the user returns to their session (the next morning),
  the screen is sorta grayed out. Keystrokes and mouse movement fail to
  elicit a reaction from the OS. I can switch to an ANSI terminal
  (Ctrl+Alt+F1), but cannot log in as the offending user there; the
  prompt will accept a username and password but never return. I CAN
  login using my localadmin, presumably because it uses UNIX
  authentication rather than LDAP/Kerberos. I have heretofore been
  unable to recover the machine as the localadmin, though. If localadmin
  attempts to sudo reboot the machine, the reboot process starts but
  never finishes.

  [Regression Potentional]
  Seems minimal as we are adding an additional condition check for expired tickets.

  
  [More info]

  Some odd things in the server syslog:

  Jun  6 07:40:15 server krb5kdc[822]: AS_REQ (7 etypes {18 17 16 23 1 3 2}) 192.168.0.59: NEEDED_PREAUTH: nfs/carina.co57.lan at CO57.LAN for krbtgt/CO57.LAN at CO57.LAN, Additional pre-authentication required
  Jun  6 07:40:15 server krb5kdc[822]: AS_REQ (7 etypes {18 17 16 23 1 3 2}) 192.168.0.59: ISSUE: authtime 1307360415, etypes {rep=18 tkt=18 ses=18}, nfs/carina.co57.lan at CO57.LAN for krbtgt/CO57.LAN at CO57.LAN
  Jun  6 07:40:15 server krb5kdc[822]: TGS_REQ (7 etypes {18 17 16 23 1 3 2}) 192.168.0.59: ISSUE: authtime 1307360415, etypes {rep=18 tkt=18 ses=18}, nfs/carina.co57.lan at CO57.LAN for nfs/server.co57.lan at CO57.LAN
  Jun  6 07:40:15 server krb5kdc[822]: TGS_REQ (3 etypes {1 3 2}) 192.168.0.59: ISSUE: authtime 1307360415, etypes {rep=18 tkt=18 ses=1}, nfs/carina.co57.lan at CO57.LAN for nfs/server.co57.lan at CO57.LAN
  Jun  6 07:40:15 server nslcd[950]: [92ef4c] nslcd_passwd_byname(nfs/carina.co57.lan): invalid user name
  Jun  6 07:46:49 server slapd[836]: <= bdb_equality_candidates: (uid) not indexed
  Jun  6 07:46:49 server slapd[836]: <= bdb_equality_candidates: (cn) not indexed
  Jun  6 07:48:51 server slapd[836]: <= bdb_equality_candidates: (uidNumber) not indexed
  Jun  6 07:49:20 server slapd[836]: <= bdb_equality_candidates: (uid) not indexed
  Jun  6 07:57:07 server slapd[836]: <= bdb_equality_candidates: (uid) not indexed
  Jun  6 07:57:07 server slapd[836]: <= bdb_equality_candidates: (cn) not indexed
  Jun  6 07:59:35 server slapd[836]: <= bdb_equality_candidates: (uid) not indexed
  Jun  6 08:00:00 server slapd[836]: <= bdb_equality_candidates: (cn) not indexed
  Jun  6 08:00:01 server slapd[836]: last message repeated 3 times

  And from all over the client syslog:

  Jun  6 10:53:28 carina kernel: [47636.670075] Error: state manager encountered RPCSEC_GSS session expired against NFSv4 server 192.168.0.2.
  Jun  6 10:53:33 carina kernel: [47641.666533] Error: state manager encountered RPCSEC_GSS session expired against NFSv4 server 192.168.0.2.
  Jun  6 10:53:38 carina kernel: [47646.662437] Error: state manager encountered RPCSEC_GSS session expired against NFSv4 server 192.168.0.2.
  Jun  6 10:53:43 carina kernel: [47651.658844] Error: state manager encountered RPCSEC_GSS session expired against NFSv4 server 192.168.0.2.
  Jun  6 10:53:48 carina kernel: [47656.655152] Error: state manager encountered RPCSEC_GSS session expired against NFSv4 server 192.168.0.2.
  Jun  6 10:53:53 carina kernel: [47661.651498] Error: state manager encountered RPCSEC_GSS session expired against NFSv4 server 192.168.0.2.
  Jun  6 10:53:58 carina kernel: [47666.647829] Error: state manager encountered RPCSEC_GSS session expired against NFSv4 server 192.168.0.2.
  Jun  6 10:54:03 carina kernel: [47671.644084] Error: state manager encountered RPCSEC_GSS session expired against NFSv4 server 192.168.0.2.
  Jun  6 10:54:08 carina kernel: [47676.640219] Error: state manager encountered RPCSEC_GSS session expired against NFSv4 server 192.168.0.2.
  Jun  6 10:54:13 carina kernel: [47681.636699] Error: state manager encountered RPCSEC_GSS session expired against NFSv4 server 192.168.0.2.
  Jun  6 10:54:18 carina kernel: [47686.632981] Error: state manager encountered RPCSEC_GSS session expired against NFSv4 server 192.168.0.2.
  Jun  6 10:54:23 carina kernel: [47691.629134] Error: state manager encountered RPCSEC_GSS session expired against NFSv4 server 192.168.0.2.
  Jun  6 10:54:28 carina kernel: [47696.625429] Error: state manager encountered RPCSEC_GSS session expired against NFSv4 server 192.168.0.2.
  Jun  6 10:54:33 carina kernel: [47701.621717] Error: state manager encountered RPCSEC_GSS session expired against NFSv4 server 192.168.0.2.
  Jun  6 10:54:38 carina kernel: [47706.617861] Error: state manager encountered RPCSEC_GSS session expired against NFSv4 server 192.168.0.2.
  Jun  6 10:54:43 carina kernel: [47711.614235] Error: state manager encountered RPCSEC_GSS session expired against NFSv4 server 192.168.0.2.
  Jun  6 10:54:48 carina kernel: [47716.610530] Error: state manager encountered RPCSEC_GSS session expired against NFSv4 server 192.168.0.2.
  Jun  6 10:54:53 carina kernel: [47721.606813] Error: state manager encountered RPCSEC_GSS session expired against NFSv4 server 192.168.0.2.

  My intuition is the following: The user's client-side Kerberos ticket
  is expiring (RPCSEC_GSS errors) and the sec=krb5 on NFS is sitting in
  a poll loop, waiting for a new one. This is somehow causing the rest
  of the system to grind to a halt, whether through resource usage or
  blocking in the kernel. I will continue to investigate and post
  evidence as I come by it. In the meantime, does anybody have any
  ideas?

  Cheers!
  ~Brian

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