loadparm: check for AD DC required VFS modules

When Samba is running as a domain controller and the "vfs objects"
parameter is not set, then the dfs_samba4 and acl_xattr modules are
automatically enabled.
However, if the "vfs objects" is defined, then the setting is left
as-is. This means that attempts to us other VFS modules have the side
effect of disabling the dfs_samba4 and acl_xattr modules, causing
unexpected behaviour, which is then blamed on the VFS modules that were
explicitly defined.

This change ensures that when running as a domain controller, Samba logs
an error if the required VFS modules are not enabled by an explicit
"vfs objects" definition.

Bug: https://bugzilla.samba.org/show_bug.cgi?id=10560

Signed-off-by: David Disseldorp <ddiss@samba.org>
Reviewed-by: Björn Jacke <bjacke@samba.org>

diff --git a/source3/param/loadparm.c b/source3/param/loadparm.c
index bef24b6821b7f1254439cbcf1d92553dc594cca8..ce41477097a91c198b511bb7b39d2fd4a1677b6b 100644 (file)
--- a/source3/param/loadparm.c
+++ b/source3/param/loadparm.c
@@ -2740,6 +2740,38 @@ static bool do_parameter(const char *pszParmName, const char *pszParmValue,
        }
 }
 
+
+static const char *ad_dc_req_vfs_mods[] = {"dfs_samba4", "acl_xattr", NULL};
+
+/*
+ * check that @vfs_objects includes all vfs modules required by an AD DC.
+ */
+static bool check_ad_dc_required_mods(const char **vfs_objects)
+{
+       int i;
+       int j;
+       int got_req;
+
+       for (i = 0; ad_dc_req_vfs_mods[i] != NULL; i++) {
+               got_req = false;
+               for (j = 0; vfs_objects[j] != NULL; j++) {
+                       if (!strwicmp(ad_dc_req_vfs_mods[i], vfs_objects[j])) {
+                               got_req = true;
+                               break;
+                       }
+               }
+               if (!got_req) {
+                       DEBUG(0, ("vfs objects specified without required AD "
+                                 "DC module: %s\n", ad_dc_req_vfs_mods[i]));
+                       return false;
+               }
+       }
+
+       DEBUG(6, ("vfs objects specified with all required AD DC modules\n"));
+       return true;
+}
+
+
 /***************************************************************************
  Initialize any local variables in the sDefault table, after parsing a
  [globals] section.
@@ -2759,7 +2791,10 @@ static void init_locals(void)
         */
        if (lp_server_role() == ROLE_ACTIVE_DIRECTORY_DC) {
                const char **vfs_objects = lp_vfs_objects(-1);
-               if (!vfs_objects || !vfs_objects[0]) {
+               if (vfs_objects != NULL) {
+                       /* ignore return, only warn if modules are missing */
+                       check_ad_dc_required_mods(vfs_objects);
+               } else {
                        if (lp_parm_const_string(-1, "xattr_tdb", "file", NULL)) {
                                lp_do_parameter(-1, "vfs objects", "dfs_samba4 acl_xattr xattr_tdb");
                        } else if (lp_parm_const_string(-1, "posix", "eadb", NULL)) {