Add clock skew handling to our kerberos code. This allows us to cope with

the DC being out of sync with the local machine.
(This used to be commit 0d28d769472ea3b98ae4c8757093dfd4499f6dd1)

3 files changed, 16 insertions, 4 deletions

diff --git a/source3/libsmb/cliconnect.c b/source3/libsmb/cliconnect.c
index 6c5c5e0b0e..298b1e52b6 100644
--- a/source3/libsmb/cliconnect.c
+++ b/source3/libsmb/cliconnect.c
@@ -431,7 +431,7 @@ static BOOL cli_session_setup_kerberos(struct cli_state *cli, char *principal, c
 	DEBUG(2,("Doing kerberos session setup\n"));
 
 	/* generate the encapsulated kerberos5 ticket */
-	negTokenTarg = spnego_gen_negTokenTarg(principal);
+	negTokenTarg = spnego_gen_negTokenTarg(principal, 0);
 
 	if (!negTokenTarg.data) return False;
 
diff --git a/source3/libsmb/clikrb5.c b/source3/libsmb/clikrb5.c
index 1fc400edb0..22bfdc0463 100644
--- a/source3/libsmb/clikrb5.c
+++ b/source3/libsmb/clikrb5.c
@@ -64,6 +64,14 @@ static krb5_error_code krb5_mk_req2(krb5_context context,
 		goto cleanup_creds;
 	}
 
+	/* cope with the ticket being in the future due to clock skew */
+	if ((unsigned)credsp->times.starttime > time(NULL)) {
+		time_t t = time(NULL);
+		int time_offset = (unsigned)credsp->times.starttime - t;
+		DEBUG(4,("Advancing clock by %d seconds to cope with clock skew\n", time_offset));
+		krb5_set_real_time(context, t + time_offset + 1, 0);
+	}
+
 	in_data.length = 0;
 	retval = krb5_mk_req_extended(context, auth_context, ap_req_options, 
 				      &in_data, credsp, outbuf);
@@ -86,7 +94,7 @@ cleanup_princ:
 /*
   get a kerberos5 ticket for the given service 
 */
-DATA_BLOB krb5_get_ticket(char *principal)
+DATA_BLOB krb5_get_ticket(char *principal, time_t time_offset)
 {
 	krb5_error_code retval;
 	krb5_data packet;
@@ -108,6 +116,10 @@ DATA_BLOB krb5_get_ticket(char *principal)
 		goto failed;
 	}
 
+	if (time_offset != 0) {
+		krb5_set_real_time(context, time(NULL) + time_offset, 0);
+	}
+
 	if ((retval = krb5_cc_default(context, &ccdef))) {
 		DEBUG(1,("krb5_cc_default failed (%s)\n",
 			 error_message(retval)));
diff --git a/source3/libsmb/clispnego.c b/source3/libsmb/clispnego.c
index 04ec6ed39e..55f49c5987 100644
--- a/source3/libsmb/clispnego.c
+++ b/source3/libsmb/clispnego.c
@@ -321,13 +321,13 @@ BOOL spnego_parse_krb5_wrap(DATA_BLOB blob, DATA_BLOB *ticket)
    generate a SPNEGO negTokenTarg packet, ready for a EXTENDED_SECURITY
    kerberos session setup 
 */
-DATA_BLOB spnego_gen_negTokenTarg(const char *principal)
+DATA_BLOB spnego_gen_negTokenTarg(const char *principal, int time_offset)
 {
 	DATA_BLOB tkt, tkt_wrapped, targ;
 	const char *krb_mechs[] = {OID_KERBEROS5_OLD, OID_NTLMSSP, NULL};
 
 	/* get a kerberos ticket for the service */
-	tkt = krb5_get_ticket(principal);
+	tkt = krb5_get_ticket(principal, time_offset);
 
 	/* wrap that up in a nice GSS-API wrapping */
 	tkt_wrapped = spnego_gen_krb5_wrap(tkt);