Clear kernel keyring in client installer, save dbdir on new connections

This patch addresses two issues:

1. If a client is previously enrolled in an IPA server and the server
   gets re-installed then the client machine may still have a keyring
   entry for the old server. This can cause a redirect from the
   session URI to the negotiate one. As a rule, always clear the keyring
   when enrolling a new client.

2. We save the NSS dbdir in the connection so that when creating a new
   session we can determine if we need to re-initialize NSS or not. Most
   of the time we do not. The dbdir was not always being preserved between
   connections which could cause an NSS_Shutdown() to happen which would
   fail because of existing usage. This preserves the dbdir information when
   a new connection is created as part of the session mechanism.

https://fedorahosted.org/freeipa/ticket/3108

ipa-client/ipa-install/ipa-client-install

@@ -42,6 +42,8 @@ try:
     from ipalib import api, errors
     from ipapython.dn import DN
     from ipapython.ssh import SSHPublicKey
+    from ipapython import kernel_keyring
+    from ipalib.rpc import COOKIE_NAME
     import SSSDConfig
     from ConfigParser import RawConfigParser
     from optparse import SUPPRESS_HELP, OptionGroup
@@ -1666,13 +1668,14 @@ def install(options, env, fstore, statestore):
         root_logger.info("Failed to add CA to the default NSS database.")
         return CLIENT_INSTALL_ERROR
 
+    host_principal = 'host/%s@%s' % (hostname, cli_realm)
     if options.on_master:
         # If on master assume kerberos is already configured properly.
         # Get the host TGT.
         os.environ['KRB5CCNAME'] = CCACHE_FILE
         try:
             run(['/usr/bin/kinit', '-k', '-t', '/etc/krb5.keytab',
-                    'host/%s@%s' % (hostname, cli_realm)])
+                    host_principal])
         except CalledProcessError, e:
             root_logger.error("Failed to obtain host TGT.")
             return CLIENT_INSTALL_ERROR
@@ -1693,6 +1696,12 @@ def install(options, env, fstore, statestore):
         root_logger.info(
             "Configured /etc/krb5.conf for IPA realm %s", cli_realm)
 
+    # Clear out any current session keyring information
+    try:
+        kernel_keyring.del_key(COOKIE_NAME % host_principal)
+    except ValueError:
+        pass
+
     # Now, let's try to connect to the server's XML-RPC interface
     try:
         api.Backend.xmlclient.connect()

ipalib/rpc.py

@@ -546,8 +546,23 @@ class xmlclient(Connectible):
                     # This shouldn't happen if we have a session but
                     # it isn't fatal.
                     pass
+
+                # Create a new serverproxy with the non-session URI. If there
+                # is an existing connection we need to save the NSS dbdir so
+                # we can skip an unnecessary NSS_Initialize() and avoid
+                # NSS_Shutdown issues.
                 serverproxy = self.create_connection(os.environ.get('KRB5CCNAME'), self.env.verbose, self.env.fallback, self.env.delegate)
+
+                dbdir = None
+                current_conn = getattr(context, self.id, None)
+                if current_conn is not None:
+                    dbdir = getattr(current_conn.conn._ServerProxy__transport, 'dbdir', None)
+                    if dbdir is not None:
+                        self.debug('Using dbdir %s' % dbdir)
                 setattr(context, self.id, Connection(serverproxy, self.disconnect))
+                if dbdir is not None:
+                    current_conn = getattr(context, self.id, None)
+                    current_conn.conn._ServerProxy__transport.dbdir = dbdir
                 return self.forward(name, *args, **kw)
             raise NetworkError(uri=server, error=e.errmsg)
         except socket.error, e: