s3-winbindd: let winbind try to use samlogon validation level 6. (bug #7945)

The benefit of this that it makes us more robust to secure channel resets
triggered from tools outside the winbind process. Long term we need to have a
shared tdb secure channel store though as well.

Guenther

Signed-off-by: Stefan Metzmacher <metze@samba.org>

Autobuild-User: Stefan Metzmacher <metze@samba.org>
Autobuild-Date: Fri Feb  4 18:11:04 CET 2011 on sn-devel-104

1 files changed, 57 insertions, 2 deletions

diff --git a/source3/winbindd/winbindd_pam.c b/source3/winbindd/winbindd_pam.c
index 760fa3bc60..68fa01f6d7 100644
--- a/source3/winbindd/winbindd_pam.c
+++ b/source3/winbindd/winbindd_pam.c
@@ -1148,6 +1148,8 @@ static NTSTATUS winbind_samlogon_retry_loop(struct winbindd_domain *domain,
 
 	do {
 		struct rpc_pipe_client *netlogon_pipe;
+		const struct pipe_auth_data *auth;
+		uint32_t neg_flags = 0;
 
 		ZERO_STRUCTP(info3);
 		retry = false;
@@ -1159,6 +1161,10 @@ static NTSTATUS winbind_samlogon_retry_loop(struct winbindd_domain *domain,
 				  nt_errstr(result)));
 			return result;
 		}
+		auth = netlogon_pipe->auth;
+		if (netlogon_pipe->dc) {
+			neg_flags = netlogon_pipe->dc->negotiate_flags;
+		}
 
 		/* It is really important to try SamLogonEx here,
 		 * because in a clustered environment, we want to use
@@ -1179,8 +1185,35 @@ static NTSTATUS winbind_samlogon_retry_loop(struct winbindd_domain *domain,
 		 * wrapping SamLogon context.
 		 *
 		 *  -- abartlet 21 April 2008
+		 *
+		 * It's also important to use NetlogonValidationSamInfo4 (6),
+		 * because it relies on the rpc transport encryption
+		 * and avoids using the global netlogon schannel
+		 * session key to en/decrypt secret information
+		 * like the user_session_key for network logons.
+		 *
+		 * [MS-APDS] 3.1.5.2 NTLM Network Logon
+		 * says NETLOGON_NEG_CROSS_FOREST_TRUSTS and
+		 * NETLOGON_NEG_AUTHENTICATED_RPC set together
+		 * are the indication that the server supports
+		 * NetlogonValidationSamInfo4 (6). And it must only
+		 * be used if "SealSecureChannel" is used.
+		 *
+		 * -- metze 4 February 2011
 		 */
 
+		if (auth == NULL) {
+			domain->can_do_validation6 = false;
+		} else if (auth->auth_type != DCERPC_AUTH_TYPE_SCHANNEL) {
+			domain->can_do_validation6 = false;
+		} else if (auth->auth_level != DCERPC_AUTH_LEVEL_PRIVACY) {
+			domain->can_do_validation6 = false;
+		} else if (!(neg_flags & NETLOGON_NEG_CROSS_FOREST_TRUSTS)) {
+			domain->can_do_validation6 = false;
+		} else if (!(neg_flags & NETLOGON_NEG_AUTHENTICATED_RPC)) {
+			domain->can_do_validation6 = false;
+		}
+
 		if (domain->can_do_samlogon_ex) {
 			result = rpccli_netlogon_sam_network_logon_ex(
 					netlogon_pipe,
@@ -1191,6 +1224,7 @@ static NTSTATUS winbind_samlogon_retry_loop(struct winbindd_domain *domain,
 					domainname,	/* target domain */
 					workstation,	/* workstation */
 					chal,
+					domain->can_do_validation6 ? 6 : 3,
 					lm_response,
 					nt_response,
 					info3);
@@ -1204,22 +1238,43 @@ static NTSTATUS winbind_samlogon_retry_loop(struct winbindd_domain *domain,
 					domainname,	/* target domain */
 					workstation,	/* workstation */
 					chal,
+					domain->can_do_validation6 ? 6 : 3,
 					lm_response,
 					nt_response,
 					info3);
 		}
 
-		attempts += 1;
-
 		if ((NT_STATUS_V(result) == DCERPC_FAULT_OP_RNG_ERROR)
 		    && domain->can_do_samlogon_ex) {
 			DEBUG(3, ("Got a DC that can not do NetSamLogonEx, "
 				  "retrying with NetSamLogon\n"));
 			domain->can_do_samlogon_ex = false;
+			/*
+			 * It's likely that the server also does not support
+			 * validation level 6
+			 */
+			domain->can_do_validation6 = false;
 			retry = true;
 			continue;
 		}
 
+		if (domain->can_do_validation6 &&
+		    (NT_STATUS_EQUAL(result, NT_STATUS_INVALID_INFO_CLASS) ||
+		     NT_STATUS_EQUAL(result, NT_STATUS_INVALID_PARAMETER) ||
+		     NT_STATUS_EQUAL(result, NT_STATUS_BUFFER_TOO_SMALL))) {
+			DEBUG(3,("Got a DC that can not do validation level 6, "
+				  "retrying with level 3\n"));
+			domain->can_do_validation6 = false;
+			retry = true;
+			continue;
+		}
+
+		/*
+		 * we increment this after the "feature negotiation"
+		 * for can_do_samlogon_ex and can_do_validation6
+		 */
+		attempts += 1;
+
 		/* We have to try a second time as cm_connect_netlogon
 		   might not yet have noticed that the DC has killed
 		   our connection. */