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ticket: 7063

Fix spurious clock skew caused by gak_fct delay

In get_in_tkt.c, a time offset is computed between the KDC's auth_time
and the current system time after the reply is decrypted.  Time may
have elapsed between these events because of a gak_fct invocation
which blocks on user input.  The resulting spurious time offset can
cause subsequent TGS-REQs to fail and can also cause the end time of
the next AS request to be in the past (issue #889) in cases where the
old ccache is opened to find the default principal.

Use the system time, without offset, for the request time of an AS
request, for more predictable kinit behavior.  Use this request time,
rather than the current time, when computing the clock skew after the
reply is decrypted.

git-svn-id: svn:// dc483132-0cff-0310-8789-dd5450dbe970
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1 parent 8c6eceb commit 2626c89efd8019853edab29c52bac951f5ba2794 ghudson committed Jan 11, 2012
Showing with 4 additions and 5 deletions.
  1. +4 −5 src/lib/krb5/krb/get_in_tkt.c
@@ -154,6 +154,7 @@ verify_as_reply(krb5_context context,
krb5_error_code retval;
int canon_req;
int canon_ok;
+ krb5_timestamp time_offset;
/* check the contents for sanity: */
if (!as_reply->enc_part2->times.starttime)
@@ -216,8 +217,8 @@ verify_as_reply(krb5_context context,
if (context->library_options & KRB5_LIBOPT_SYNC_KDCTIME) {
- retval = krb5_set_real_time(context,
- as_reply->enc_part2->times.authtime, -1);
+ time_offset = as_reply->enc_part2->times.authtime - time_now;
+ retval = krb5_set_time_offsets(context, time_offset, 0);
if (retval)
return retval;
} else {
@@ -742,9 +743,7 @@ restart_init_creds_loop(krb5_context context, krb5_init_creds_context ctx,
if (code != 0)
goto cleanup;
- code = krb5_timeofday(context, &ctx->request_time);
- if (code != 0)
- goto cleanup;
+ ctx->request_time = time(NULL);
code = krb5int_fast_as_armor(context, ctx->fast_state,
ctx->opte, ctx->request);

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