s4:dsdb Move module configuration from each ldb into samba_dsdb.c

This makes getting the module order correct, the obligation of Samba4
developers, and not system administrators.  In particular, once an ldb
is updated to use only the 'samba_dsdb' module, no further changes to the
ldb should be required when upgrading to later Samba4 versions.

(thanks to metze for the suggestion of samba_dsdb as a long-term
stable name for the module)

Andrew Bartlett

source4/dsdb/samdb/ldb_modules/config.mk

@@ -8,6 +8,17 @@ DSDB_MODULE_HELPERS_OBJ_FILES = $(dsdbsrcdir)/samdb/ldb_modules/util.o
 $(eval $(call proto_header_template,$(dsdbsrcdir)/samdb/ldb_modules/util_proto.h,$(DSDB_MODULE_HELPERS_OBJ_FILES:.o=.c)))
 
 
+################################################
+# Start MODULE ldb_samba_dsdb
+[MODULE::ldb_samba_dsdb]
+SUBSYSTEM = LIBLDB
+PRIVATE_DEPENDENCIES = SAMDB LIBTALLOC LIBEVENTS LIBNDR
+INIT_FUNCTION = LDB_MODULE(samba_dsdb)
+# End MODULE ldb_samba_dsdb
+################################################
+
+ldb_samba_dsdb_OBJ_FILES = $(dsdbsrcdir)/samdb/ldb_modules/samba_dsdb.o
+
 ################################################
 # Start MODULE ldb_objectguid
 [MODULE::ldb_objectguid]

source4/dsdb/samdb/ldb_modules/partition.h

@@ -47,6 +47,8 @@ struct partition_private_data {
 
 	uint64_t metadata_seq;
 	uint32_t in_transaction;
+
+	struct ldb_message *forced_module_msg;
 };
 
 #include "dsdb/samdb/ldb_modules/partition_proto.h"

source4/dsdb/samdb/ldb_modules/partition_init.c

@@ -129,7 +129,7 @@ static int partition_load_modules(struct ldb_context *ldb,
 static int partition_reload_metadata(struct ldb_module *module, struct partition_private_data *data, TALLOC_CTX *mem_ctx, struct ldb_message **_msg) 
 {
 	int ret;
-	struct ldb_message *msg;
+	struct ldb_message *msg, *module_msg;
 	struct ldb_result *res;
 	struct ldb_context *ldb = ldb_module_get_ctx(module);
 	const char *attrs[] = { "partition", "replicateEntries", "modules", "ldapBackend", NULL };
@@ -148,7 +148,16 @@ static int partition_reload_metadata(struct ldb_module *module, struct partition
 		return ret;
 	}
 
-	ret = partition_load_modules(ldb, data, msg);			
+	/* When used from Samba4, this message is set by the samba4
+	 * module, as a fixed value not read from the DB.  This avoids
+	 * listing modules in the DB */
+	if (data->forced_module_msg) {
+		module_msg = data->forced_module_msg;
+	} else {
+		module_msg = msg;
+	}
+
+	ret = partition_load_modules(ldb, data, module_msg);
 	if (ret != LDB_SUCCESS) {
 		return ret;
 	}
@@ -790,7 +799,7 @@ int partition_init(struct ldb_module *module)
 {
 	int ret;
 	TALLOC_CTX *mem_ctx = talloc_new(module);
-
+	struct ldb_context *ldb = ldb_module_get_ctx(module);
 	struct partition_private_data *data;
 
 	if (!mem_ctx) {
@@ -802,6 +811,14 @@ int partition_init(struct ldb_module *module)
 		return LDB_ERR_OPERATIONS_ERROR;
 	}
 
+	/* When used from Samba4, this message is set by the samba4
+	 * module, as a fixed value not read from the DB.  This avoids
+	 * listing modules in the DB */
+	data->forced_module_msg = talloc_get_type(
+		ldb_get_opaque(ldb,
+			       DSDB_OPAQUE_PARTITION_MODULE_MSG_OPAQUE_NAME),
+		struct ldb_message);
+
 	/* This loads the partitions */
 	ret = partition_reload_if_required(module, data);
 	if (ret != LDB_SUCCESS) {
@@ -813,14 +830,14 @@ int partition_init(struct ldb_module *module)
 
 	ret = ldb_mod_register_control(module, LDB_CONTROL_DOMAIN_SCOPE_OID);
 	if (ret != LDB_SUCCESS) {
-		ldb_debug(ldb_module_get_ctx(module), LDB_DEBUG_ERROR,
+		ldb_debug(ldb, LDB_DEBUG_ERROR,
 			"partition: Unable to register control with rootdse!\n");
 		return LDB_ERR_OPERATIONS_ERROR;
 	}
 
 	ret = ldb_mod_register_control(module, LDB_CONTROL_SEARCH_OPTIONS_OID);
 	if (ret != LDB_SUCCESS) {
-		ldb_debug(ldb_module_get_ctx(module), LDB_DEBUG_ERROR,
+		ldb_debug(ldb, LDB_DEBUG_ERROR,
 			"partition: Unable to register control with rootdse!\n");
 		return LDB_ERR_OPERATIONS_ERROR;
 	}

source4/dsdb/samdb/ldb_modules/samba_dsdb.c

@@ -0,0 +1,360 @@
+/*
+   Samba4 module loading module
+
+   Copyright (C) Andrew Bartlett <abartlet@samba.org> 2009
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/*
+ *  Name: ldb
+ *
+ *  Component: Samba4 module loading module
+ *
+ *  Description: Implement a single 'module' in the ldb database,
+ *  which loads the remaining modules based on 'choice of configuration' attributes
+ *
+ *  This is to avoid forcing a reprovision of the ldb databases when we change the internal structure of the code
+ *
+ *  Author: Andrew Bartlett
+ */
+
+#include "includes.h"
+#include "lib/ldb/include/ldb.h"
+#include "lib/ldb/include/ldb_errors.h"
+#include "lib/ldb/include/ldb_module.h"
+#include "lib/ldb/include/ldb_private.h"
+
+#include "dsdb/samdb/ldb_modules/util.h"
+#include "dsdb/samdb/samdb.h"
+
+static int read_at_rootdse_record(struct ldb_context *ldb, struct ldb_module *module, TALLOC_CTX *mem_ctx,
+				  struct ldb_message **msg)
+{
+	int ret;
+	static const char *rootdse_attrs[] = { "defaultNamingContext", "configurationNamingContext", "schemaNamingContext", NULL };
+	struct ldb_result *rootdse_res;
+	struct ldb_dn *rootdse_dn;
+	TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
+	if (!tmp_ctx) {
+		ldb_oom(ldb);
+		return LDB_ERR_OPERATIONS_ERROR;
+	}
+
+	rootdse_dn = ldb_dn_new(tmp_ctx, ldb, "@ROOTDSE");
+	if (!rootdse_dn) {
+		talloc_free(tmp_ctx);
+		ldb_oom(ldb);
+		return LDB_ERR_OPERATIONS_ERROR;
+	}
+
+	ret = dsdb_module_search_dn(module, tmp_ctx, &rootdse_res, rootdse_dn, rootdse_attrs, 0);
+	if (ret != LDB_SUCCESS) {
+		talloc_free(tmp_ctx);
+		return ret;
+	}
+
+	talloc_steal(mem_ctx, rootdse_res->msgs);
+	*msg = rootdse_res->msgs[0];
+
+	talloc_free(tmp_ctx);
+
+	return ret;
+}
+
+static int prepare_modules_line(struct ldb_context *ldb,
+				TALLOC_CTX *mem_ctx,
+				const struct ldb_message *rootdse_msg,
+				struct ldb_message *msg, const char *backend_attr,
+				const char *backend_mod, const char **backend_mod_list)
+{
+	int ret;
+	const char **backend_full_list;
+	const char *backend_dn;
+	char *mod_list_string;
+	char *full_string;
+	TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
+	if (!tmp_ctx) {
+		ldb_oom(ldb);
+		return LDB_ERR_OPERATIONS_ERROR;
+	}
+
+	if (backend_attr) {
+		backend_dn = ldb_msg_find_attr_as_string(rootdse_msg, backend_attr, NULL);
+		if (!backend_dn) {
+			ldb_asprintf_errstring(ldb,
+					       "samba_dsdb_init: "
+					       "unable to read %s from %s:%s",
+					       backend_attr, ldb_dn_get_linearized(rootdse_msg->dn),
+					       ldb_errstring(ldb));
+			return LDB_ERR_CONSTRAINT_VIOLATION;
+		}
+	} else {
+		backend_dn = "*";
+	}
+
+	if (backend_mod) {
+		backend_full_list = (const char **)str_list_make_single(tmp_ctx, backend_mod);
+	} else {
+		backend_full_list = (const char **)str_list_make_empty(tmp_ctx);
+	}
+	if (!backend_full_list) {
+		talloc_free(tmp_ctx);
+		ldb_oom(ldb);
+		return LDB_ERR_OPERATIONS_ERROR;
+	}
+
+	backend_full_list = str_list_append_const(backend_full_list, backend_mod_list);
+	if (!backend_full_list) {
+		talloc_free(tmp_ctx);
+		ldb_oom(ldb);
+		return LDB_ERR_OPERATIONS_ERROR;
+	}
+
+	mod_list_string = str_list_join(tmp_ctx, backend_full_list, ',');
+	if (!mod_list_string) {
+		talloc_free(tmp_ctx);
+		ldb_oom(ldb);
+		return LDB_ERR_OPERATIONS_ERROR;
+	}
+
+	full_string = talloc_asprintf(tmp_ctx, "%s:%s", backend_dn, mod_list_string);
+	ret = ldb_msg_add_steal_string(msg, "modules", full_string);
+	talloc_free(tmp_ctx);
+	return ret;
+}
+
+static int samba_dsdb_init(struct ldb_module *module)
+{
+	struct ldb_context *ldb = ldb_module_get_ctx(module);
+	int ret, len, i;
+	TALLOC_CTX *tmp_ctx = talloc_new(module);
+	struct ldb_result *res;
+	struct ldb_message *rootdse_msg, *partition_msg;
+	struct ldb_dn *samba_dsdb_dn;
+	struct ldb_module *backend_module, *module_chain;
+	const char **final_module_list, **reverse_module_list;
+	/*
+	  Add modules to the list to activate them by default
+	  beware often order is important
+
+	  Some Known ordering constraints:
+	  - rootdse must be first, as it makes redirects from "" -> cn=rootdse
+	  - extended_dn_in must be before objectclass.c, as it resolves the DN
+	  - objectclass must be before password_hash, because password_hash checks
+	    that the objectclass is of type person (filled in by objectclass
+	    module when expanding the objectclass list)
+	  - partition must be last
+	  - each partition has its own module list then
+
+	  The list is presented here as a set of declarations to show the
+	  stack visually - the code below then handles the creation of the list
+	  based on the parameters loaded from the database.
+	*/
+	static const char *modules_list[] = {"resolve_oids",
+					     "rootdse",
+					     "lazy_commit",
+					     "paged_results",
+					     "ranged_results",
+					     "anr",
+					     "server_sort",
+					     "asq",
+					     "extended_dn_store",
+					     "extended_dn_in",
+					     "rdn_name",
+					     "objectclass",
+					     "descriptor",
+					     "acl",
+					     "samldb",
+					     "password_hash",
+					     "operational",
+					     "kludge_acl",
+					     "schema_load",
+					     "instancetype",
+					     NULL };
+
+	const char *objectguid_module;
+	/* if serverrole == "domain controller": */
+	const char *repl_meta_data = "repl_meta_data";
+	/*    else: */
+        const char *objectguid = "objectguid";
+
+	const char **link_modules;
+	static const char *tdb_modules_list[] = {
+		"subtree_rename",
+		"subtree_delete",
+		"linked_attributes",
+		NULL};
+
+	const char *extended_dn_module;
+	const char *extended_dn_module_ldb = "extended_dn_out_ldb";
+	const char *extended_dn_module_fds = "extended_dn_out_ldb";
+	const char *extended_dn_module_openldap = "extended_dn_out_ldb";
+
+	static const char *modules_list2[] = {"show_deleted",
+					      "new_partition",
+					      "partition",
+					      NULL };
+
+	const char **backend_modules;
+	static const char *fedora_ds_backend_modules[] = {
+		"nsuniqueid", "paged_searches", NULL };
+	static const char *openldap_backend_modules[] = {
+		"nsuniqueid", "paged_searches", NULL };
+
+	static const char *samba_dsdb_attrs[] = { "backendType", "serverRole", NULL };
+	const char *backendType, *serverRole;
+
+	if (!tmp_ctx) {
+		ldb_oom(ldb);
+		return LDB_ERR_OPERATIONS_ERROR;
+	}
+
+	samba_dsdb_dn = ldb_dn_new(tmp_ctx, ldb, "@SAMBA_DSDB");
+	if (!samba_dsdb_dn) {
+		talloc_free(tmp_ctx);
+		ldb_oom(ldb);
+		return LDB_ERR_OPERATIONS_ERROR;
+	}
+
+#define CHECK_LDB_RET(check_ret)				\
+	do {							\
+		if (check_ret != LDB_SUCCESS) {			\
+			talloc_free(tmp_ctx);			\
+			return check_ret;			\
+		}						\
+	} while (0)
+
+	ret = dsdb_module_search_dn(module, tmp_ctx, &res, samba_dsdb_dn, samba_dsdb_attrs, 0);
+	if (ret != LDB_SUCCESS) {
+		talloc_free(tmp_ctx);
+		return ret;
+	}
+
+	backendType = ldb_msg_find_attr_as_string(res->msgs[0], "backendType", "ldb");
+	serverRole = ldb_msg_find_attr_as_string(res->msgs[0], "serverRole", NULL);
+
+	backend_modules = NULL;
+	if (strcasecmp(backendType, "ldb") == 0) {
+		if (strcasecmp(serverRole, "dc") == 0 || strcasecmp(serverRole, "domain controller") == 0) {
+			objectguid_module = repl_meta_data;
+		} else {
+			objectguid_module = objectguid;
+		}
+		extended_dn_module = extended_dn_module_ldb;
+		link_modules = tdb_modules_list;
+	} else {
+		objectguid_module = NULL;
+		link_modules = NULL;
+		if (strcasecmp(backendType, "fedora-ds")) {
+			backend_modules = fedora_ds_backend_modules;
+			extended_dn_module = extended_dn_module_fds;
+		} else if (strcasecmp(backendType, "openldap")) {
+			backend_modules = openldap_backend_modules;
+			extended_dn_module = extended_dn_module_openldap;
+		}
+	}
+
+#define CHECK_MODULE_LIST \
+	do {							\
+		if (!final_module_list) {			\
+			talloc_free(tmp_ctx);			\
+			ldb_oom(ldb);				\
+			return LDB_ERR_OPERATIONS_ERROR;	\
+		}						\
+	} while (0)
+
+	final_module_list = str_list_copy_const(tmp_ctx, modules_list);
+	CHECK_MODULE_LIST;
+
+	final_module_list = str_list_add_const(final_module_list, objectguid_module);
+	CHECK_MODULE_LIST;
+
+	final_module_list = str_list_append_const(final_module_list, link_modules);
+	CHECK_MODULE_LIST;
+
+	final_module_list = str_list_add_const(final_module_list, extended_dn_module);
+	CHECK_MODULE_LIST;
+
+	final_module_list = str_list_append_const(final_module_list, modules_list2);
+	CHECK_MODULE_LIST;
+
+
+	ret = read_at_rootdse_record(ldb, module, tmp_ctx, &rootdse_msg);
+	CHECK_LDB_RET(ret);
+
+	partition_msg = ldb_msg_new(tmp_ctx);
+	partition_msg->dn = ldb_dn_new(partition_msg, ldb, "@" DSDB_OPAQUE_PARTITION_MODULE_MSG_OPAQUE_NAME);
+
+	ret = prepare_modules_line(ldb, tmp_ctx,
+				   rootdse_msg,
+				   partition_msg, "defaultNamingContext",
+				   "pdc_fsmo", backend_modules);
+	CHECK_LDB_RET(ret);
+
+	ret = prepare_modules_line(ldb, tmp_ctx,
+				   rootdse_msg,
+				   partition_msg, "configurationNamingContext",
+				   "naming_fsmo", backend_modules);
+	CHECK_LDB_RET(ret);
+
+	ret = prepare_modules_line(ldb, tmp_ctx,
+				   rootdse_msg,
+				   partition_msg, "schemaNamingContext",
+				   "schema_data", backend_modules);
+	CHECK_LDB_RET(ret);
+
+	ret = prepare_modules_line(ldb, tmp_ctx,
+				   rootdse_msg,
+				   partition_msg, NULL,
+				   NULL, backend_modules);
+	CHECK_LDB_RET(ret);
+
+	ret = ldb_set_opaque(ldb, DSDB_OPAQUE_PARTITION_MODULE_MSG_OPAQUE_NAME, partition_msg);
+	CHECK_LDB_RET(ret);
+
+	talloc_steal(ldb, partition_msg);
+
+	/* Now prepare the module chain.  Oddly, we must give it to ldb_load_modules_list in REVERSE */
+	for (len = 0; final_module_list[len]; len++) { /* noop */};
+
+	reverse_module_list = talloc_array(tmp_ctx, const char *, len+1);
+	if (!reverse_module_list) {
+		talloc_free(tmp_ctx);
+		ldb_oom(ldb);
+		return LDB_ERR_OPERATIONS_ERROR;
+	}
+	for (i=0; i < len; i++) {
+		reverse_module_list[i] = final_module_list[(len - 1) - i];
+	}
+	reverse_module_list[i] = NULL;
+
+	/* The backend (at least until the partitions module
+	 * reconfigures things) is the next module in the currently
+	 * loaded chain */
+	backend_module = module->next;
+	ret = ldb_load_modules_list(ldb, reverse_module_list, backend_module, &module_chain);
+	CHECK_LDB_RET(ret);
+
+	talloc_free(tmp_ctx);
+	/* Set this as the 'next' module, so that we effectivly append it to module chain */
+	module->next = module_chain;
+
+	return ldb_next_init(module);
+}
+
+const struct ldb_module_ops ldb_samba_dsdb_module_ops = {
+	.name		   = "samba_dsdb",
+	.init_context	   = samba_dsdb_init,
+};

source4/dsdb/samdb/samdb.h

@@ -140,4 +140,6 @@ struct dsdb_extended_dn_store_format {
 	bool store_extended_dn_in_ldb;
 };
 
+#define DSDB_OPAQUE_PARTITION_MODULE_MSG_OPAQUE_NAME "DSDB_OPAQUE_PARTITION_MODULE_MSG"
+
 #endif /* __SAMDB_H__ */

source4/scripting/python/samba/provision.py

@@ -549,79 +549,10 @@ def setup_samdb_partitions(samdb_path, setup_path, message, lp, session_info,
     samdb = Ldb(url=samdb_path, session_info=session_info, 
                 lp=lp, options=["modules:"])
 
-    #Add modules to the list to activate them by default
-    #beware often order is important
-    #
-    # Some Known ordering constraints:
-    # - rootdse must be first, as it makes redirects from "" -> cn=rootdse
-    # - extended_dn_in must be before objectclass.c, as it resolves the DN
-    # - objectclass must be before password_hash, because password_hash checks
-    #   that the objectclass is of type person (filled in by objectclass
-    #   module when expanding the objectclass list)
-    # - partition must be last
-    # - each partition has its own module list then
-    modules_list = ["resolve_oids",
-                    "rootdse",
-                    "lazy_commit",
-                    "paged_results",
-                    "ranged_results",
-                    "anr",
-                    "server_sort",
-                    "asq",
-                    "extended_dn_store",
-                    "extended_dn_in",
-                    "rdn_name",
-                    "objectclass",
-                    "descriptor",
-                    "acl",
-                    "samldb",
-                    "password_hash",
-                    "operational",
-                    "kludge_acl", 
-                    "schema_load",
-                    "instancetype"]
-    if serverrole == "domain controller":
-        objectguid_module = "repl_meta_data"
-    else:
-        objectguid_module = "objectguid"
-    tdb_modules_list = [
-                    "subtree_rename",
-                    "subtree_delete",
-                    "linked_attributes"]
-    extended_dn_module = "extended_dn_out_ldb"
-    modules_list2 = ["show_deleted",
-                     "new_partition",
-                     "partition"]
-
-    backend_modules = []
-
     ldap_backend_line = "# No LDAP backend"
     if provision_backend.type is not "ldb":
         ldap_backend_line = "ldapBackend: %s" % provision_backend.ldapi_uri
 
-        # The LDAP backends assign the objectGUID on thier own
-        objectguid_module = None
-        # OpenLDAP and FDS handles subtree renames, so we don't want to do any of these things
-        tdb_modules_list = []
-
-        if provision_backend.ldap_backend_type == "fedora-ds":
-            backend_modules = ["nsuniqueid", "paged_searches"]
-            extended_dn_module_list = ["extended_dn_out_fds"];
-        elif provision_backend.ldap_backend_type == "openldap":
-            backend_modules = ["entryuuid", "paged_searches"]
-            extended_dn_module_list = ["extended_dn_out_openldap"]
-
-    if objectguid_module is not None:
-        modules_list.append(objectguid_module)
-
-    for m in tdb_modules_list:
-        modules_list.append(m)
-
-    modules_list.append(extended_dn_module)
-
-    for m in modules_list2:
-        modules_list.append(m)
-
     samdb.transaction_start()
     try:
         message("Setting up sam.ldb partitions and settings")
@@ -629,16 +560,14 @@ def setup_samdb_partitions(samdb_path, setup_path, message, lp, session_info,
                 "SCHEMADN": ldb.Dn(schema.ldb, names.schemadn).get_casefold(), 
                 "CONFIGDN": ldb.Dn(schema.ldb, names.configdn).get_casefold(),
                 "DOMAINDN": ldb.Dn(schema.ldb, names.domaindn).get_casefold(),
-                "SCHEMADN_MOD": "schema_data",
-                "CONFIGDN_MOD": "naming_fsmo",
-                "DOMAINDN_MOD": "pdc_fsmo",
-                "MODULES_LIST": ",".join(modules_list),
-                "BACKEND_MOD": ",".join(backend_modules),
                 "LDAP_BACKEND_LINE": ldap_backend_line,
         })
 
         
-        samdb.load_ldif_file_add(setup_path("provision_init.ldif"))
+        setup_add_ldif(samdb, setup_path("provision_init.ldif"), {
+                "BACKEND_TYPE": provision_backend.type,
+                "SERVER_ROLE": serverrole
+                })
 
         message("Setting up sam.ldb rootDSE")
         setup_samdb_rootdse(samdb, setup_path, names)

source4/setup/provision_init.ldif

@@ -20,3 +20,10 @@ passwordAttribute: initialAuthIncoming
 
 dn: @OPTIONS
 checkBaseOnSearch: TRUE
+
+dn: @SAMBA_DSDB
+backendType: ${BACKEND_TYPE}
+serverRole: ${SERVER_ROLE}
+
+dn: @MODULES
+@LIST: samba_dsdb

source4/setup/provision_partitions.ldif

@@ -2,11 +2,5 @@ dn: @PARTITION
 replicateEntries: @ATTRIBUTES
 replicateEntries: @INDEXLIST
 replicateEntries: @OPTIONS
-modules:${SCHEMADN}:${SCHEMADN_MOD},${BACKEND_MOD}
-modules:${CONFIGDN}:${CONFIGDN_MOD},${BACKEND_MOD}
-modules:${DOMAINDN}:${DOMAINDN_MOD},${BACKEND_MOD}
-modules:*:${BACKEND_MOD}
 ${LDAP_BACKEND_LINE}
 
-dn: @MODULES
-@LIST: ${MODULES_LIST}