svn rev #22890: trunk/src/lib/krb5/krb/

[ghudson@MIT.EDU]

http://src.mit.edu/fisheye/changelog/krb5/?cs=22890
Commit By: ghudson
Log Message:
ticket: 6573
subject: Fix preauth looping in krb5_get_init_creds
tags: pullup
target_version: 1.7.1

In 1.7, krb5_get_init_creds will continue attempting the same built-in
preauth mechanism (e.g. encrypted timestamp) until the loop counter
maxes out.  Until the preauth framework can remember not to retry
built-in mechanisms, only continue with preauth after a PREAUTH_FAILED
error resulting from optimistic preauth.



Changed Files:
U   trunk/src/lib/krb5/krb/get_in_tkt.c
Modified: trunk/src/lib/krb5/krb/get_in_tkt.c
===================================================================
--- trunk/src/lib/krb5/krb/get_in_tkt.c	2009-10-13 19:38:42 UTC (rev 22889)
+++ trunk/src/lib/krb5/krb/get_in_tkt.c	2009-10-13 19:43:17 UTC (rev 22890)
@@ -1055,6 +1055,21 @@
     return ret;
 }
 
+/* Decide whether to continue trying AS-REQ preauthentication. */
+static krb5_boolean
+should_continue_preauth(krb5_ui_4 error, int loopcount)
+{
+    /*
+     * Continue on PREAUTH_FAILED only on the first iteration, which
+     * would imply that we did optimistic preauth unsuccessfully.  We
+     * could continue on later iterations if the preauth framework
+     * reliably remembered what mechanisms had been tried, but
+     * currently it does not do so for built-in mechanisms.
+     */
+    return (error == KDC_ERR_PREAUTH_REQUIRED ||
+	    (error == KDC_ERR_PREAUTH_FAILED && loopcount == 0));
+}
+
 krb5_error_code KRB5_CALLCONV
 krb5_get_init_creds(krb5_context context,
 		    krb5_creds *creds,
@@ -1412,8 +1427,7 @@
 					   &out_padata, &retry);
 	  if (ret !=0)
 	    goto cleanup;
-	  if ((err_reply->error == KDC_ERR_PREAUTH_REQUIRED ||err_reply->error == KDC_ERR_PREAUTH_FAILED)
-&& retry) {
+	  if (should_continue_preauth(err_reply->error, loopcount) && retry) {
 		/* reset the list of preauth types to try */
 		if (preauth_to_use) {
 		    krb5_free_pa_data(context, preauth_to_use);