[libvirt] [PATCH] daemon: Avoid 'Could not find keytab file' in syslog

[Cole Robinson]

On F17 at least, every time libvirtd starts we get this in syslog:

libvirtd: Could not find keytab file: /etc/libvirt/krb5.tab: No such file or directory

This comes from cyrus-sasl, and happens regardless of whether the
gssapi plugin is requested, which is what actually uses
/etc/libvirt/krb5.tab.

While cyrus-sasl shouldn't complain, we can easily make it shut up by
commenting out the keytab value by default.

Also update the keytab comment to the more modern one from qemu's
sasl config file.
---
 daemon/libvirtd.sasl | 9 ++++++---
 docs/auth.html.in    | 3 ++-
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/daemon/libvirtd.sasl b/daemon/libvirtd.sasl
index e24a130..bfa056f 100644
--- a/daemon/libvirtd.sasl
+++ b/daemon/libvirtd.sasl
@@ -18,9 +18,12 @@ mech_list: digest-md5
 #   qemu+tcp://hostname/system?auth=sasl.gssapi
 #mech_list: digest-md5 gssapi
 
-# MIT kerberos ignores this option & needs KRB5_KTNAME env var.
-# May be useful for other non-Linux OS though....
-keytab: /etc/libvirt/krb5.tab
+# Some older builds of MIT kerberos on Linux ignore this option &
+# instead need KRB5_KTNAME env var.
+# For modern Linux, and other OS, this should be sufficient
+#
+# There is no default value here, uncomment if you need this
+#keytab: /etc/libvirt/krb5.tab
 
 # If using digest-md5 for username/passwds, then this is the file
 # containing the passwds. Use 'saslpasswd2 -a libvirt [username]'
diff --git a/docs/auth.html.in b/docs/auth.html.in
index 60e4f11..d792eb1 100644
--- a/docs/auth.html.in
+++ b/docs/auth.html.in
@@ -233,7 +233,8 @@ The SASL mechanism configured by default is DIGEST-MD5, which provides a basic
 username+password style authentication. To enable Kerberos single-sign-on instead,
 the libvirt SASL configuration file must be changed. This is <code>/etc/sasl2/libvirt.conf</code>.
 The <code>mech_list</code> parameter must first be changed to <code>gssapi</code>
-instead of the default <code>digest-md5</code>. If SASL is enabled on the UNIX
+instead of the default <code>digest-md5</code>, and keytab should be set to
+<code>/etc/libvirt/krb5.tab</code> . If SASL is enabled on the UNIX
 and/or TLS sockets, Kerberos will also be used for them. Like DIGEST-MD5, the Kerberos
 mechanism provides data encryption of the session.
 </p>
-- 
1.7.11.7