r15698: An attempt to make the winbind lookup_usergroups() call in security=ads

more scalable:

The most efficient way is to use the "tokenGroups" attribute which gives
the nested group membership. As this attribute can not always be
retrieved when binding with the machine account (the only garanteed way
to get the tokenGroups I could find is when the machine account is a
member of the "Pre Win2k Access" builtin group).

Our current fallback when "tokenGroups" failed is looking for all groups
where the userdn was in the "member" attribute. This behaves not very
well in very large AD domains.

The patch first tries the "memberOf" attribute on the user's dn in that
case and directly retrieves the group's sids by using the LDAP Extended
DN control from the user's object.

The way to pass down the control to the ldap search call is rather
painfull and probably will be rearranged later on.

Successfully tested on win2k sp0, win2k sp4, wink3 sp1 and win2k3 r2.

Guenther
(This used to be commit 7d766b5505e4099ef7dd4e88bb000ebe38d71bd0)

1 files changed, 112 insertions, 16 deletions

diff --git a/source3/nsswitch/winbindd_ads.c b/source3/nsswitch/winbindd_ads.c
index 3dc26f4cfa3..8259fd7cd36 100644
--- a/source3/nsswitch/winbindd_ads.c
+++ b/source3/nsswitch/winbindd_ads.c
@@ -542,11 +542,11 @@ done:
 
 /* Lookup groups a user is a member of - alternate method, for when
    tokenGroups are not available. */
-static NTSTATUS lookup_usergroups_alt(struct winbindd_domain *domain,
-				      TALLOC_CTX *mem_ctx,
-				      const char *user_dn, 
-				      DOM_SID *primary_group,
-				      size_t *p_num_groups, DOM_SID **user_sids)
+static NTSTATUS lookup_usergroups_member(struct winbindd_domain *domain,
+					 TALLOC_CTX *mem_ctx,
+					 const char *user_dn, 
+					 DOM_SID *primary_group,
+					 size_t *p_num_groups, DOM_SID **user_sids)
 {
 	ADS_STATUS rc;
 	NTSTATUS status = NT_STATUS_UNSUCCESSFUL;
@@ -559,7 +559,7 @@ static NTSTATUS lookup_usergroups_alt(struct winbindd_domain *domain,
 	char *escaped_dn;
 	size_t num_groups = 0;
 
-	DEBUG(3,("ads: lookup_usergroups_alt\n"));
+	DEBUG(3,("ads: lookup_usergroups_member\n"));
 
 	ads = ads_cached_connection(domain);
 
@@ -573,9 +573,6 @@ static NTSTATUS lookup_usergroups_alt(struct winbindd_domain *domain,
 		goto done;
 	}
 
-	/* buggy server, no tokenGroups.  Instead lookup what groups this user
-	   is a member of by DN search on member*/
-
 	if (!(ldap_exp = talloc_asprintf(mem_ctx, "(&(member=%s)(objectCategory=group))", escaped_dn))) {
 		DEBUG(1,("lookup_usergroups(dn=%s) asprintf failed!\n", user_dn));
 		SAFE_FREE(escaped_dn);
@@ -624,7 +621,7 @@ static NTSTATUS lookup_usergroups_alt(struct winbindd_domain *domain,
 	*p_num_groups = num_groups;
 	status = (user_sids != NULL) ? NT_STATUS_OK : NT_STATUS_NO_MEMORY;
 
-	DEBUG(3,("ads lookup_usergroups (alt) for dn=%s\n", user_dn));
+	DEBUG(3,("ads lookup_usergroups (member) succeeded for dn=%s\n", user_dn));
 done:
 	if (res) 
 		ads_msgfree(ads, res);
@@ -632,6 +629,89 @@ done:
 	return status;
 }
 
+/* Lookup groups a user is a member of - alternate method, for when
+   tokenGroups are not available. */
+static NTSTATUS lookup_usergroups_memberof(struct winbindd_domain *domain,
+					   TALLOC_CTX *mem_ctx,
+					   const char *user_dn, 
+					   DOM_SID *primary_group,
+					   size_t *p_num_groups, DOM_SID **user_sids)
+{
+	ADS_STATUS rc;
+	NTSTATUS status = NT_STATUS_UNSUCCESSFUL;
+	int count;
+	void *res = NULL;
+	ADS_STRUCT *ads;
+	const char *attrs[] = {"memberOf", NULL};
+	size_t num_groups = 0;
+	DOM_SID *group_sids = NULL;
+	int i;
+
+	DEBUG(3,("ads: lookup_usergroups_memberof\n"));
+
+	ads = ads_cached_connection(domain);
+
+	if (!ads) {
+		domain->last_status = NT_STATUS_SERVER_DISABLED;
+		goto done;
+	}
+
+	rc = ads_search_retry_extended_dn(ads, &res, user_dn, attrs, 
+					  ADS_EXTENDED_DN_HEX_STRING);
+	
+	if (!ADS_ERR_OK(rc) || !res) {
+		DEBUG(1,("lookup_usergroups_memberof ads_search member=%s: %s\n", 
+			user_dn, ads_errstr(rc)));
+		return ads_ntstatus(rc);
+	}
+	
+	count = ads_count_replies(ads, res);
+
+	if (count == 0) {
+		status = NT_STATUS_NO_SUCH_USER;
+		goto done;
+	}
+	
+	*user_sids = NULL;
+	num_groups = 0;
+
+	/* always add the primary group to the sid array */
+	add_sid_to_array(mem_ctx, primary_group, user_sids, &num_groups);
+
+	count = ads_pull_sids_from_extendeddn(ads, mem_ctx, res, "memberOf", 
+					      ADS_EXTENDED_DN_HEX_STRING, 
+					      &group_sids);
+	if (count == 0) {
+		DEBUG(1,("No memberOf for this user?!?\n"));
+		status = NT_STATUS_NO_MEMORY;
+		goto done;
+	}
+
+	for (i=0; i<count; i++) {
+
+		/* ignore Builtin groups from ADS - Guenther */
+		if (sid_check_is_in_builtin(&group_sids[i])) {
+			continue;
+		}
+		       
+		add_sid_to_array(mem_ctx, &group_sids[i], user_sids,
+				 &num_groups);
+	
+	}
+
+	*p_num_groups = num_groups;
+	status = (user_sids != NULL) ? NT_STATUS_OK : NT_STATUS_NO_MEMORY;
+
+	DEBUG(3,("ads lookup_usergroups (memberof) succeeded for dn=%s\n", user_dn));
+done:
+	TALLOC_FREE(group_sids);
+	if (res) 
+		ads_msgfree(ads, res);
+
+	return status;
+}
+
+
 /* Lookup groups a user is a member of. */
 static NTSTATUS lookup_usergroups(struct winbindd_domain *domain,
 				  TALLOC_CTX *mem_ctx,
@@ -717,13 +797,29 @@ static NTSTATUS lookup_usergroups(struct winbindd_domain *domain,
 	/* there must always be at least one group in the token, 
 	   unless we are talking to a buggy Win2k server */
 
+	/* actually this only happens when the machine account has no read
+	 * permissions on the tokenGroup attribute - gd */
+
 	if (count == 0) {
 
-		status = lookup_usergroups_alt(domain, mem_ctx, user_dn, 
-					       &primary_group,
-					       &num_groups, user_sids);
-		*p_num_groups = (uint32)num_groups;
-		return status;
+		/* no tokenGroups */
+		
+		/* lookup what groups this user is a member of by DN search on
+		 * "memberOf" */
+
+		status = lookup_usergroups_memberof(domain, mem_ctx, user_dn,
+						    &primary_group,
+						    p_num_groups, user_sids);
+		if (NT_STATUS_IS_OK(status)) {
+			return status;
+		}
+
+		/* lookup what groups this user is a member of by DN search on
+		 * "member" */
+
+		return lookup_usergroups_member(domain, mem_ctx, user_dn, 
+						&primary_group,
+						p_num_groups, user_sids);
 	}
 
 	*user_sids = NULL;
@@ -745,7 +841,7 @@ static NTSTATUS lookup_usergroups(struct winbindd_domain *domain,
 	*p_num_groups = (uint32)num_groups;
 	status = (user_sids != NULL) ? NT_STATUS_OK : NT_STATUS_NO_MEMORY;
 
-	DEBUG(3,("ads lookup_usergroups for sid=%s\n",
+	DEBUG(3,("ads lookup_usergroups (tokenGroups) succeeded for sid=%s\n",
 		 sid_to_string(sid_string, sid)));
 done:
 	return status;