/*
   SAM ldb module

   Copyright (C) Andrew Bartlett <abartlet@samba.org> 2005-2014
   Copyright (C) Simo Sorce  2004-2008
   Copyright (C) Matthias Dieter Wallnöfer 2009-2011
   Copyright (C) Matthieu Patou 2012
   Copyright (C) Catalyst.Net Ltd 2017

   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: ldb samldb module
 *
 *  Description: various internal DSDB triggers - most for SAM specific objects
 *
 *  Author: Simo Sorce
 */

#include "includes.h"
#include "libcli/ldap/ldap_ndr.h"
#include "ldb_module.h"
#include "auth/auth.h"
#include "dsdb/samdb/samdb.h"
#include "dsdb/samdb/ldb_modules/util.h"
#include "dsdb/samdb/ldb_modules/ridalloc.h"
#include "libcli/security/security.h"
#include "librpc/gen_ndr/ndr_security.h"
#include "ldb_wrap.h"
#include "param/param.h"
#include "libds/common/flag_mapping.h"
#include "system/network.h"
#include "librpc/gen_ndr/irpc.h"
#include "lib/util/smb_strtox.h"

#undef strcasecmp

struct samldb_ctx;
enum samldb_add_type {
	SAMLDB_TYPE_USER,
	SAMLDB_TYPE_GROUP,
	SAMLDB_TYPE_CLASS,
	SAMLDB_TYPE_ATTRIBUTE
};

typedef int (*samldb_step_fn_t)(struct samldb_ctx *);

struct samldb_step {
	struct samldb_step *next;
	samldb_step_fn_t fn;
};

struct samldb_ctx {
	struct ldb_module *module;
	struct ldb_request *req;

	/* used for add operations */
	enum samldb_add_type type;

	/*
	 * should we apply the need_trailing_dollar restriction to
	 * samAccountName
	 */

	bool need_trailing_dollar;

	/* the resulting message */
	struct ldb_message *msg;

	/* used in "samldb_find_for_defaultObjectCategory" */
	struct ldb_dn *dn, *res_dn;

	/* all the async steps necessary to complete the operation */
	struct samldb_step *steps;
	struct samldb_step *curstep;

	/* If someone set an ares to forward controls and response back to the caller */
	struct ldb_reply *ares;
};

static struct samldb_ctx *samldb_ctx_init(struct ldb_module *module,
					  struct ldb_request *req)
{
	struct ldb_context *ldb;
	struct samldb_ctx *ac;

	ldb = ldb_module_get_ctx(module);

	ac = talloc_zero(req, struct samldb_ctx);
	if (ac == NULL) {
		ldb_oom(ldb);
		return NULL;
	}

	ac->module = module;
	ac->req = req;

	return ac;
}

static int samldb_add_step(struct samldb_ctx *ac, samldb_step_fn_t fn)
{
	struct samldb_step *step, *stepper;

	step = talloc_zero(ac, struct samldb_step);
	if (step == NULL) {
		return ldb_oom(ldb_module_get_ctx(ac->module));
	}

	step->fn = fn;

	if (ac->steps == NULL) {
		ac->steps = step;
		ac->curstep = step;
	} else {
		if (ac->curstep == NULL)
			return ldb_operr(ldb_module_get_ctx(ac->module));
		for (stepper = ac->curstep; stepper->next != NULL;
			stepper = stepper->next);
		stepper->next = step;
	}

	return LDB_SUCCESS;
}

static int samldb_first_step(struct samldb_ctx *ac)
{
	if (ac->steps == NULL) {
		return ldb_operr(ldb_module_get_ctx(ac->module));
	}

	ac->curstep = ac->steps;
	return ac->curstep->fn(ac);
}

static int samldb_next_step(struct samldb_ctx *ac)
{
	if (ac->curstep->next) {
		ac->curstep = ac->curstep->next;
		return ac->curstep->fn(ac);
	}

	/* We exit the samldb module here. If someone set an "ares" to forward
	 * controls and response back to the caller, use them. */
	if (ac->ares) {
		return ldb_module_done(ac->req, ac->ares->controls,
				       ac->ares->response, LDB_SUCCESS);
	} else {
		return ldb_module_done(ac->req, NULL, NULL, LDB_SUCCESS);
	}
}

static int samldb_get_single_valued_attr(struct ldb_context *ldb,
					 struct samldb_ctx *ac,
					 const char *attr,
					 const char **value)
{
	/*
	 * The steps we end up going through to get and check a single valued
	 * attribute.
	 */
	struct ldb_message_element *el = NULL;
	int ret;

	*value = NULL;

	ret = dsdb_get_expected_new_values(ac,
					   ac->msg,
					   attr,
					   &el,
					   ac->req->operation);

	if (ret != LDB_SUCCESS) {
		return ret;
	}
	if (el == NULL) {
		/* we are not affected */
		return LDB_SUCCESS;
	}

	if (el->num_values > 1) {
		ldb_asprintf_errstring(
			ldb,
		        "samldb: %s has %u values, should be single-valued!",
			attr, el->num_values);
		return LDB_ERR_CONSTRAINT_VIOLATION;
	} else if (el->num_values == 0) {
		ldb_asprintf_errstring(
			ldb,
			"samldb: new value for %s "
			"not provided for mandatory, single-valued attribute!",
			attr);
		return LDB_ERR_OBJECT_CLASS_VIOLATION;
	}


	if (el->values[0].length == 0) {
		ldb_asprintf_errstring(
			ldb,
			"samldb: %s is of zero length, should have a value!",
			attr);
		return LDB_ERR_OBJECT_CLASS_VIOLATION;
	}

	*value = (char *)el->values[0].data;

	return LDB_SUCCESS;
}

static int samldb_unique_attr_check(struct samldb_ctx *ac, const char *attr,
				    const char *attr_conflict,
				    struct ldb_dn *base_dn)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	const char * const no_attrs[] = { NULL };
	struct ldb_result *res = NULL;
	const char *str = NULL;
	const char *enc_str = NULL;
	int ret;

	ret = samldb_get_single_valued_attr(ldb, ac, attr, &str);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	if (str == NULL) {
		/* the attribute wasn't found */
		return LDB_SUCCESS;
	}

	enc_str = ldb_binary_encode_string(ac, str);
	if (enc_str == NULL) {
		return ldb_module_oom(ac->module);
	}

	/*
	 * No other object should have the attribute with this value.
	 */
	if (attr_conflict != NULL) {
		ret = dsdb_module_search(ac->module, ac, &res,
					 base_dn,
					 LDB_SCOPE_SUBTREE, no_attrs,
					 DSDB_FLAG_NEXT_MODULE, ac->req,
					 "(|(%s=%s)(%s=%s))",
					 attr, enc_str,
					 attr_conflict, enc_str);
	} else {
		ret = dsdb_module_search(ac->module, ac, &res,
					 base_dn,
					 LDB_SCOPE_SUBTREE, no_attrs,
					 DSDB_FLAG_NEXT_MODULE, ac->req,
					 "(%s=%s)", attr, enc_str);
	}
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	if (res->count > 1) {
		return ldb_operr(ldb);
	} else if (res->count == 1) {
		if (ldb_dn_compare(res->msgs[0]->dn, ac->msg->dn) != 0) {
			ldb_asprintf_errstring(ldb,
					       "samldb: %s '%s' already in use!",
					       attr, enc_str);
			return LDB_ERR_ENTRY_ALREADY_EXISTS;
		}
	}
	talloc_free(res);

	return LDB_SUCCESS;
}



static inline int samldb_sam_account_upn_clash_sub_search(
	struct samldb_ctx *ac,
	TALLOC_CTX *mem_ctx,
	struct ldb_dn *base_dn,
	const char *attr,
	const char *value,
	const char *err_msg
	)
{
	/*
	 * A very specific helper function for samldb_sam_account_upn_clash(),
	 * where we end up doing this same thing several times in a row.
	 */
	const char * const no_attrs[] = { NULL };
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	struct ldb_result *res = NULL;
	int ret;
	char *enc_value = ldb_binary_encode_string(ac, value);
	if (enc_value == NULL) {
		return ldb_module_oom(ac->module);
	}
	ret = dsdb_module_search(ac->module, mem_ctx, &res,
				 base_dn,
				 LDB_SCOPE_SUBTREE, no_attrs,
				 DSDB_FLAG_NEXT_MODULE, ac->req,
				 "(%s=%s)",
				 attr, enc_value);
	talloc_free(enc_value);

	if (ret != LDB_SUCCESS) {
		return ret;
	} else if (res->count > 1) {
		return ldb_operr(ldb);
	} else if (res->count == 1) {
		if (ldb_dn_compare(res->msgs[0]->dn, ac->msg->dn) != 0){
			ldb_asprintf_errstring(ldb,
					       "samldb: %s '%s' "
					       "is already in use %s",
					       attr, value, err_msg);
			/* different errors for different attrs */
			if (strcasecmp("userPrincipalName", attr) == 0) {
				return LDB_ERR_CONSTRAINT_VIOLATION;
			}
			return LDB_ERR_ENTRY_ALREADY_EXISTS;
		}
	}
	return LDB_SUCCESS;
}

static int samaccountname_bad_chars_check(struct samldb_ctx *ac,
					  const char *name)
{
	/*
	 * The rules here are based on
	 *
	 * https://social.technet.microsoft.com/wiki/contents/articles/11216.active-directory-requirements-for-creating-objects.aspx
	 *
	 * Windows considers UTF-8 sequences that map to "similar" characters
	 * (e.g. 'a', 'ā') to be the same sAMAccountName, and we don't. Names
	 * that are not valid UTF-8 *are* allowed.
	 *
	 * Additionally, Samba collapses multiple spaces, and Windows doesn't.
	 */
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	size_t i;

	for (i = 0; name[i] != '\0'; i++) {
		uint8_t c = name[i];
		char *p = NULL;
		if (c < 32 || c == 127) {
			ldb_asprintf_errstring(
				ldb,
				"samldb: sAMAccountName contains invalid "
				"0x%.2x character\n", c);
			return LDB_ERR_CONSTRAINT_VIOLATION;
		}
		p = strchr("\"[]:;|=+*?<>/\\,", c);
		if (p != NULL) {
			ldb_asprintf_errstring(
				ldb,
				"samldb: sAMAccountName contains invalid "
				"'%c' character\n", c);
			return LDB_ERR_CONSTRAINT_VIOLATION;
		}
	}

	if (i == 0) {
		ldb_asprintf_errstring(
			ldb,
			"samldb: sAMAccountName is empty\n");
		return LDB_ERR_CONSTRAINT_VIOLATION;
	}

	if (name[i - 1] == '.') {
		ldb_asprintf_errstring(
			ldb,
			"samldb: sAMAccountName ends with '.'");
		return LDB_ERR_CONSTRAINT_VIOLATION;
	}
	return LDB_SUCCESS;
}

static int samldb_sam_account_upn_clash(struct samldb_ctx *ac)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	int ret;
	struct ldb_dn *base_dn = ldb_get_default_basedn(ldb);
	TALLOC_CTX *tmp_ctx = NULL;
	const char *real_sam = NULL;
	const char *real_upn = NULL;
	char *implied_sam = NULL;
	char *implied_upn = NULL;
	const char *realm = NULL;

	ret = samldb_get_single_valued_attr(ldb, ac,
					    "sAMAccountName",
					    &real_sam);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	ret = samldb_get_single_valued_attr(ldb, ac,
					    "userPrincipalName",
					    &real_upn);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	if (real_upn == NULL && real_sam == NULL) {
		/* Not changing these things, so we're done */
		return LDB_SUCCESS;
	}

	tmp_ctx = talloc_new(ac);
	realm = samdb_dn_to_dns_domain(tmp_ctx, base_dn);
	if (realm == NULL) {
		talloc_free(tmp_ctx);
		return ldb_operr(ldb);
	}

	if (real_upn != NULL) {
		/*
		 * note we take the last @ in the upn because the first (i.e.
		 * sAMAccountName equivalent) part can contain @.
		 *
		 * It is also OK (per Windows) for a UPN to have zero @s.
		 */
		char *at = NULL;
		char *upn_realm = NULL;
		implied_sam = talloc_strdup(tmp_ctx, real_upn);
		if (implied_sam == NULL) {
			talloc_free(tmp_ctx);
			return ldb_module_oom(ac->module);
		}

		at = strrchr(implied_sam, '@');
		if (at == NULL) {
			/*
			 * there is no @ in this UPN, so we treat the whole
			 * thing as a sAMAccountName for the purposes of a
			 * clash.
			 */
			DBG_INFO("samldb: userPrincipalName '%s' contains "
				 "no '@' character\n", implied_sam);
		} else {
			/*
			 * Now, this upn only implies a sAMAccountName if the
			 * realm is our realm. So we need to compare the tail
			 * of the upn to the realm.
			 */
			*at = '\0';
			upn_realm = at + 1;
			if (strcasecmp(upn_realm, realm) != 0) {
				/* implied_sam is not the implied
				 * sAMAccountName after all, because it is
				 * from a different realm. */
				TALLOC_FREE(implied_sam);
			}
		}
	}

	if (real_sam != NULL) {
		implied_upn = talloc_asprintf(tmp_ctx, "%s@%s",
					      real_sam, realm);
		if (implied_upn == NULL) {
			talloc_free(tmp_ctx);
			return ldb_module_oom(ac->module);
		}
	}

	/*
	 * Now we have all of the actual and implied names, in which to search
	 * for conflicts.
	 */
	if (real_sam != NULL) {
		ret = samldb_sam_account_upn_clash_sub_search(
			ac, tmp_ctx, base_dn, "sAMAccountName",
			real_sam, "");

		if (ret != LDB_SUCCESS) {
			talloc_free(tmp_ctx);
			return ret;
		}
		ret = samaccountname_bad_chars_check(ac, real_sam);
		if (ret != LDB_SUCCESS) {
			talloc_free(tmp_ctx);
			return ret;
		}
	}
	if (implied_upn != NULL) {
		ret = samldb_sam_account_upn_clash_sub_search(
			ac, tmp_ctx, base_dn, "userPrincipalName", implied_upn,
			"(implied by sAMAccountName)");

		if (ret != LDB_SUCCESS) {
			talloc_free(tmp_ctx);
			return ret;
		}
	}
	if (real_upn != NULL) {
		ret = samldb_sam_account_upn_clash_sub_search(
			ac, tmp_ctx, base_dn, "userPrincipalName",
			real_upn, "");

		if (ret != LDB_SUCCESS) {
			talloc_free(tmp_ctx);
			return ret;
		}
	}
	if (implied_sam != NULL) {
		ret = samldb_sam_account_upn_clash_sub_search(
			ac, tmp_ctx, base_dn, "sAMAccountName", implied_sam,
			"(implied by userPrincipalName)");
		if (ret != LDB_SUCCESS) {
			talloc_free(tmp_ctx);
			return ret;
		}
	}

	talloc_free(tmp_ctx);
	return LDB_SUCCESS;
}


/* This is run during an add or modify */
static int samldb_sam_accountname_valid_check(struct samldb_ctx *ac)
{
	int ret = 0;
	bool is_admin;
	struct security_token *user_token = NULL;
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	struct ldb_message_element *el = NULL;

	ret = dsdb_get_expected_new_values(ac,
					   ac->msg,
					   "samAccountName",
					   &el,
					   ac->req->operation);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	if (el == NULL || el->num_values == 0) {
		ldb_asprintf_errstring(ldb,
			"%08X: samldb: 'samAccountName' can't be deleted/empty!",
			W_ERROR_V(WERR_DS_ILLEGAL_MOD_OPERATION));
		if (ac->req->operation == LDB_ADD) {
			return LDB_ERR_CONSTRAINT_VIOLATION;
		} else {
			return LDB_ERR_UNWILLING_TO_PERFORM;
		}
	}

	ret = samldb_unique_attr_check(ac, "samAccountName", NULL,
				       ldb_get_default_basedn(
					       ldb_module_get_ctx(ac->module)));

	/*
	 * Error code munging to try and match what must be some quite
	 * strange code-paths in Windows
	 */
	if (ret == LDB_ERR_CONSTRAINT_VIOLATION
	    && ac->req->operation == LDB_MODIFY) {
		ret = LDB_ERR_ATTRIBUTE_OR_VALUE_EXISTS;
	} else if (ret == LDB_ERR_OBJECT_CLASS_VIOLATION) {
		ret = LDB_ERR_CONSTRAINT_VIOLATION;
	}
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	ret = samldb_sam_account_upn_clash(ac);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	if (!ac->need_trailing_dollar) {
		return LDB_SUCCESS;
	}

	/* This does not permit a single $ */
	if (el->values[0].length < 2) {
		ldb_asprintf_errstring(ldb,
				       "%08X: samldb: 'samAccountName' "
				       "can't just be one character!",
			W_ERROR_V(WERR_DS_ILLEGAL_MOD_OPERATION));
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	user_token = acl_user_token(ac->module);
	if (user_token == NULL) {
		return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
	}

	is_admin
		= security_token_has_builtin_administrators(user_token);

	if (is_admin) {
		/*
		 * Administrators are allowed to select strange names.
		 * This is poor practice but not prevented.
		 */
		return false;
	}

	if (el->values[0].data[el->values[0].length - 1] != '$') {
		ldb_asprintf_errstring(ldb,
				       "%08X: samldb: 'samAccountName' "
				       "must have a trailing $!",
			W_ERROR_V(WERR_DS_ILLEGAL_MOD_OPERATION));
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}
	if (el->values[0].data[el->values[0].length - 2] == '$') {
		ldb_asprintf_errstring(ldb,
				       "%08X: samldb: 'samAccountName' "
				       "must not have a double trailing $!",
			W_ERROR_V(WERR_DS_ILLEGAL_MOD_OPERATION));
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	return ret;
}

static int samldb_schema_attributeid_valid_check(struct samldb_ctx *ac)
{
	int ret = samldb_unique_attr_check(ac, "attributeID", "governsID",
					   ldb_get_schema_basedn(
						   ldb_module_get_ctx(ac->module)));
	if (ret == LDB_ERR_ENTRY_ALREADY_EXISTS) {
		ret = LDB_ERR_UNWILLING_TO_PERFORM;
	}
	return ret;
}

static int samldb_schema_governsid_valid_check(struct samldb_ctx *ac)
{
	int ret = samldb_unique_attr_check(ac, "governsID", "attributeID",
					   ldb_get_schema_basedn(
						   ldb_module_get_ctx(ac->module)));
	if (ret == LDB_ERR_ENTRY_ALREADY_EXISTS) {
		ret = LDB_ERR_UNWILLING_TO_PERFORM;
	}
	return ret;
}

static int samldb_schema_ldapdisplayname_valid_check(struct samldb_ctx *ac)
{
	int ret = samldb_unique_attr_check(ac, "lDAPDisplayName", NULL,
					   ldb_get_schema_basedn(
						   ldb_module_get_ctx(ac->module)));
	if (ret == LDB_ERR_ENTRY_ALREADY_EXISTS) {
		ret = LDB_ERR_UNWILLING_TO_PERFORM;
	}
	return ret;
}

static int samldb_check_linkid_used(struct samldb_ctx *ac,
				    struct dsdb_schema *schema,
				    struct ldb_dn *schema_dn,
				    struct ldb_context *ldb,
				    int32_t linkID,
				    bool *found)
{
	int ret;
	struct ldb_result *ldb_res;

	if (dsdb_attribute_by_linkID(schema, linkID)) {
		*found = true;
		return LDB_SUCCESS;
	}

	ret = dsdb_module_search(ac->module, ac,
				 &ldb_res,
				 schema_dn, LDB_SCOPE_ONELEVEL, NULL,
				 DSDB_FLAG_NEXT_MODULE,
				 ac->req,
				 "(linkID=%d)", linkID);
	if (ret != LDB_SUCCESS) {
		ldb_debug_set(ldb, LDB_DEBUG_ERROR,
			      __location__": Searching for linkID=%d failed - %s\n",
			      linkID,
			      ldb_errstring(ldb));
		return ldb_operr(ldb);
	}

	*found = (ldb_res->count != 0);
	talloc_free(ldb_res);

	return LDB_SUCCESS;
}

/* Find the next open forward linkID in the schema. */
static int samldb_generate_next_linkid(struct samldb_ctx *ac,
				       struct dsdb_schema *schema,
				       int32_t *next_linkID)
{
	int ret;
	struct ldb_context *ldb;
	struct ldb_dn *schema_dn;
	bool linkID_used = true;

	/*
	 * Windows starts at about 0xB0000000 in order to stop potential
	 * collisions with future additions to the schema. We pass this
	 * around as a signed int sometimes, but this should be sufficient.
	 */
	*next_linkID = 0x40000000;

	ldb = ldb_module_get_ctx(ac->module);
	schema_dn = ldb_get_schema_basedn(ldb);

	while (linkID_used) {
		*next_linkID += 2;
		ret = samldb_check_linkid_used(ac, schema,
					       schema_dn, ldb,
					       *next_linkID, &linkID_used);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	return LDB_SUCCESS;
}

static int samldb_schema_add_handle_linkid(struct samldb_ctx *ac)
{
	int ret;
	bool ok, found = false;
	struct ldb_message_element *el;
	const char *enc_str;
	const struct dsdb_attribute *attr;
	struct ldb_context *ldb;
	struct ldb_dn *schema_dn;
	struct dsdb_schema *schema;
	int32_t new_linkID = 0;

	ldb = ldb_module_get_ctx(ac->module);
	schema = dsdb_get_schema(ldb, ac);
	schema_dn = ldb_get_schema_basedn(ldb);

	ret = dsdb_get_expected_new_values(ac,
					   ac->msg,
					   "linkID",
					   &el,
					   ac->req->operation);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	if (el == NULL || el->num_values == 0) {
		return LDB_SUCCESS;
	}

	enc_str = ldb_binary_encode(ac, el->values[0]);
	if (enc_str == NULL) {
		return ldb_module_oom(ac->module);
	}

	ok = (strcmp(enc_str, "0") == 0);
	if (ok) {
		return LDB_SUCCESS;
	}

	/*
	 * This OID indicates that the caller wants the linkID
	 * to be automatically generated. We therefore assign
	 * it the next open linkID.
	 */
	ok = (strcmp(enc_str, "1.2.840.113556.1.2.50") == 0);
	if (ok) {
		ret = samldb_generate_next_linkid(ac, schema, &new_linkID);
		if (ret != LDB_SUCCESS) {
			return ret;
		}

		ldb_msg_remove_element(ac->msg, el);
		ret = samdb_msg_add_int(ldb, ac->msg, ac->msg, "linkID",
					new_linkID);
		return ret;
	}

	/*
	 * Using either the attributeID or lDAPDisplayName of
	 * another attribute in the linkID field indicates that
	 * we should make this the backlink of that attribute.
	 */
	attr = dsdb_attribute_by_attributeID_oid(schema, enc_str);
	if (attr == NULL) {
		attr = dsdb_attribute_by_lDAPDisplayName(schema, enc_str);
	}

	if (attr != NULL) {
		/*
		 * The attribute we're adding this as a backlink of must
		 * be a forward link.
		 */
		if (attr->linkID % 2 != 0) {
			return LDB_ERR_UNWILLING_TO_PERFORM;
		}

		new_linkID = attr->linkID + 1;

		/* Make sure that this backlink doesn't already exist. */
		ret = samldb_check_linkid_used(ac, schema,
					       schema_dn, ldb,
					       new_linkID, &found);
		if (ret != LDB_SUCCESS) {
			return ret;
		}

		if (found) {
			return LDB_ERR_UNWILLING_TO_PERFORM;
		}

		ldb_msg_remove_element(ac->msg, el);
		ret = samdb_msg_add_int(ldb, ac->msg, ac->msg, "linkID",
					new_linkID);
		return ret;
	}

	schema_dn = ldb_get_schema_basedn(ldb_module_get_ctx(ac->module));
	ret = samldb_unique_attr_check(ac, "linkID", NULL, schema_dn);
	if (ret == LDB_ERR_ENTRY_ALREADY_EXISTS) {
		return LDB_ERR_UNWILLING_TO_PERFORM;
	} else {
		return ret;
	}
}

static int samldb_check_mapiid_used(struct samldb_ctx *ac,
				    struct dsdb_schema *schema,
				    struct ldb_dn *schema_dn,
				    struct ldb_context *ldb,
				    int32_t mapiid,
				    bool *found)
{
	int ret;
	struct ldb_result *ldb_res;

	ret = dsdb_module_search(ac->module, ac,
				 &ldb_res,
				 schema_dn, LDB_SCOPE_ONELEVEL, NULL,
				 DSDB_FLAG_NEXT_MODULE,
				 ac->req,
				 "(mAPIID=%d)", mapiid);
	if (ret != LDB_SUCCESS) {
		ldb_debug_set(ldb, LDB_DEBUG_ERROR,
			      __location__": Searching for mAPIID=%d failed - %s\n",
			      mapiid,
			      ldb_errstring(ldb));
		return ldb_operr(ldb);
	}

	*found = (ldb_res->count != 0);
	talloc_free(ldb_res);

	return LDB_SUCCESS;
}

static int samldb_generate_next_mapiid(struct samldb_ctx *ac,
				       struct dsdb_schema *schema,
				       int32_t *next_mapiid)
{
	int ret;
	struct ldb_context *ldb;
	struct ldb_dn *schema_dn;
	bool mapiid_used = true;

	/* Windows' generation seems to start about here */
	*next_mapiid = 60000;

	ldb = ldb_module_get_ctx(ac->module);
	schema_dn = ldb_get_schema_basedn(ldb);

	while (mapiid_used) {
		*next_mapiid += 1;
		ret = samldb_check_mapiid_used(ac, schema,
					       schema_dn, ldb,
					       *next_mapiid, &mapiid_used);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	return LDB_SUCCESS;
}

static int samldb_schema_add_handle_mapiid(struct samldb_ctx *ac)
{
	int ret;
	bool ok;
	struct ldb_message_element *el;
	const char *enc_str;
	struct ldb_context *ldb;
	struct ldb_dn *schema_dn;
	struct dsdb_schema *schema;
	int32_t new_mapiid = 0;

	/*
	 * The mAPIID of a new attribute should be automatically generated
	 * if a specific OID is put as the mAPIID, as according to
	 * [MS-ADTS] 3.1.1.2.3.2.
	 */

	ldb = ldb_module_get_ctx(ac->module);
	schema = dsdb_get_schema(ldb, ac);
	schema_dn = ldb_get_schema_basedn(ldb);

	ret = dsdb_get_expected_new_values(ac,
					   ac->msg,
					   "mAPIID",
					   &el,
					   ac->req->operation);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	if (el == NULL || el->num_values == 0) {
		return LDB_SUCCESS;
	}

	enc_str = ldb_binary_encode(ac, el->values[0]);
	if (enc_str == NULL) {
		return ldb_module_oom(ac->module);
	}

	ok = (strcmp(enc_str, "1.2.840.113556.1.2.49") == 0);
	if (ok) {
		ret = samldb_generate_next_mapiid(ac, schema,
						  &new_mapiid);
		if (ret != LDB_SUCCESS) {
			return ret;
		}

		ldb_msg_remove_element(ac->msg, el);
		ret = samdb_msg_add_int(ldb, ac->msg, ac->msg,
					"mAPIID", new_mapiid);
		return ret;
	}

	schema_dn = ldb_get_schema_basedn(ldb_module_get_ctx(ac->module));
	ret = samldb_unique_attr_check(ac, "mAPIID", NULL, schema_dn);
	if (ret == LDB_ERR_ENTRY_ALREADY_EXISTS) {
		return LDB_ERR_UNWILLING_TO_PERFORM;
	} else {
		return ret;
	}
}

/* sAMAccountName handling */
static int samldb_generate_sAMAccountName(struct samldb_ctx *ac,
					  struct ldb_message *msg)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	char *name;

	/*
	 * This is currently a Samba-only behaviour, to add a trailing
	 * $ even for the generated accounts.
	 */

	if (ac->need_trailing_dollar) {
		/* Format: $000000-00000000000$ */
		name = talloc_asprintf(msg, "$%.6X-%.6X%.5X$",
				       (unsigned int)generate_random(),
				       (unsigned int)generate_random(),
				       (unsigned int)generate_random());
	} else {
		/* Format: $000000-000000000000 */

		name = talloc_asprintf(msg, "$%.6X-%.6X%.6X",
				       (unsigned int)generate_random(),
				       (unsigned int)generate_random(),
				       (unsigned int)generate_random());
	}
	if (name == NULL) {
		return ldb_oom(ldb);
	}
	return ldb_msg_add_steal_string(msg, "sAMAccountName", name);
}

static int samldb_check_sAMAccountName(struct samldb_ctx *ac)
{
	int ret;

	if (ldb_msg_find_element(ac->msg, "sAMAccountName") == NULL) {
		ret = samldb_generate_sAMAccountName(ac, ac->msg);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	ret = samldb_sam_accountname_valid_check(ac);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	return samldb_next_step(ac);
}


static bool samldb_msg_add_sid(struct ldb_message *msg,
				const char *name,
				const struct dom_sid *sid)
{
	struct ldb_val v;
	enum ndr_err_code ndr_err;

	ndr_err = ndr_push_struct_blob(&v, msg, sid,
				       (ndr_push_flags_fn_t)ndr_push_dom_sid);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		return false;
	}
	return (ldb_msg_add_value(msg, name, &v, NULL) == 0);
}


/* allocate a SID using our RID Set */
static int samldb_allocate_sid(struct samldb_ctx *ac)
{
	uint32_t rid;
	struct dom_sid *sid;
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	int ret;

	ret = ridalloc_allocate_rid(ac->module, &rid, ac->req);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	sid = dom_sid_add_rid(ac, samdb_domain_sid(ldb), rid);
	if (sid == NULL) {
		return ldb_module_oom(ac->module);
	}

	if ( ! samldb_msg_add_sid(ac->msg, "objectSid", sid)) {
		return ldb_operr(ldb);
	}

	return samldb_next_step(ac);
}

/*
  see if a krbtgt_number is available
 */
static bool samldb_krbtgtnumber_available(struct samldb_ctx *ac,
					  uint32_t krbtgt_number)
{
	TALLOC_CTX *tmp_ctx = talloc_new(ac);
	struct ldb_result *res;
	const char * const no_attrs[] = { NULL };
	int ret;

	ret = dsdb_module_search(ac->module, tmp_ctx, &res,
				 ldb_get_default_basedn(ldb_module_get_ctx(ac->module)),
				 LDB_SCOPE_SUBTREE, no_attrs,
				 DSDB_FLAG_NEXT_MODULE,
				 ac->req,
				 "(msDS-SecondaryKrbTgtNumber=%u)",
				 krbtgt_number);
	if (ret == LDB_SUCCESS && res->count == 0) {
		talloc_free(tmp_ctx);
		return true;
	}
	talloc_free(tmp_ctx);
	return false;
}

/* special handling for add in RODC join */
static int samldb_rodc_add(struct samldb_ctx *ac)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	uint32_t krbtgt_number, i_start, i;
	int ret;
	struct ldb_val newpass_utf16;

	/* find a unused msDS-SecondaryKrbTgtNumber */
	i_start = generate_random() & 0xFFFF;
	if (i_start == 0) {
		i_start = 1;
	}

	for (i=i_start; i<=0xFFFF; i++) {
		if (samldb_krbtgtnumber_available(ac, i)) {
			krbtgt_number = i;
			goto found;
		}
	}
	for (i=1; i<i_start; i++) {
		if (samldb_krbtgtnumber_available(ac, i)) {
			krbtgt_number = i;
			goto found;
		}
	}

	ldb_asprintf_errstring(ldb,
			       "%08X: Unable to find available msDS-SecondaryKrbTgtNumber",
			       W_ERROR_V(WERR_NO_SYSTEM_RESOURCES));
	return LDB_ERR_OTHER;

found:

	ldb_msg_remove_attr(ac->msg, "msDS-SecondaryKrbTgtNumber");
	ret = samdb_msg_append_uint(ldb, ac->msg, ac->msg,
				    "msDS-SecondaryKrbTgtNumber", krbtgt_number,
				    LDB_FLAG_INTERNAL_DISABLE_VALIDATION);
	if (ret != LDB_SUCCESS) {
		return ldb_operr(ldb);
	}

	ret = ldb_msg_add_fmt(ac->msg, "sAMAccountName", "krbtgt_%u",
			      krbtgt_number);
	if (ret != LDB_SUCCESS) {
		return ldb_operr(ldb);
	}

	newpass_utf16 = data_blob_talloc_zero(ac->module, 256);
	if (newpass_utf16.data == NULL) {
		return ldb_oom(ldb);
	}
	/*
	 * Note that the password_hash module will ignore
	 * this value and use it's own generate_secret_buffer()
	 * that's why we can just use generate_random_buffer()
	 * here.
	 */
	generate_random_buffer(newpass_utf16.data, newpass_utf16.length);
	ret = ldb_msg_add_steal_value(ac->msg, "clearTextPassword", &newpass_utf16);
	if (ret != LDB_SUCCESS) {
		return ldb_operr(ldb);
	}

	return samldb_next_step(ac);
}

static int samldb_find_for_defaultObjectCategory(struct samldb_ctx *ac)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	struct ldb_result *res;
	const char * const no_attrs[] = { NULL };
	int ret;

	ac->res_dn = NULL;

	ret = dsdb_module_search(ac->module, ac, &res,
				 ac->dn, LDB_SCOPE_BASE, no_attrs,
				 DSDB_SEARCH_SHOW_DN_IN_STORAGE_FORMAT
				 | DSDB_FLAG_NEXT_MODULE,
				 ac->req,
				 "(objectClass=classSchema)");
	if (ret == LDB_ERR_NO_SUCH_OBJECT) {
		/* Don't be pricky when the DN doesn't exist if we have the */
		/* RELAX control specified */
		if (ldb_request_get_control(ac->req,
					    LDB_CONTROL_RELAX_OID) == NULL) {
			ldb_set_errstring(ldb,
					  "samldb_find_defaultObjectCategory: "
					  "Invalid DN for 'defaultObjectCategory'!");
			return LDB_ERR_CONSTRAINT_VIOLATION;
		}
	}
	if ((ret != LDB_ERR_NO_SUCH_OBJECT) && (ret != LDB_SUCCESS)) {
		return ret;
	}

	if (ret == LDB_SUCCESS) {
		/* ensure the defaultObjectCategory has a full GUID */
		struct ldb_message *m;
		m = ldb_msg_new(ac->msg);
		if (m == NULL) {
			return ldb_oom(ldb);
		}
		m->dn = ac->msg->dn;
		if (ldb_msg_add_string(m, "defaultObjectCategory",
				       ldb_dn_get_extended_linearized(m, res->msgs[0]->dn, 1)) !=
		    LDB_SUCCESS) {
			return ldb_oom(ldb);
		}
		m->elements[0].flags = LDB_FLAG_MOD_REPLACE;

		ret = dsdb_module_modify(ac->module, m,
					 DSDB_FLAG_NEXT_MODULE,
					 ac->req);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}


	ac->res_dn = ac->dn;

	return samldb_next_step(ac);
}

/**
 * msDS-IntId attributeSchema attribute handling
 * during LDB_ADD request processing
 */
static int samldb_add_handle_msDS_IntId(struct samldb_ctx *ac)
{
	int ret;
	bool id_exists;
	uint32_t msds_intid;
	int32_t system_flags;
	struct ldb_context *ldb;
	struct ldb_result *ldb_res;
	struct ldb_dn *schema_dn;
	struct samldb_msds_intid_persistant *msds_intid_struct;
	struct dsdb_schema *schema;

	ldb = ldb_module_get_ctx(ac->module);
	schema_dn = ldb_get_schema_basedn(ldb);

	/* replicated update should always go through */
	if (ldb_request_get_control(ac->req,
				    DSDB_CONTROL_REPLICATED_UPDATE_OID)) {
		return LDB_SUCCESS;
	}

	/* msDS-IntId is handled by system and should never be
	 * passed by clients */
	if (ldb_msg_find_element(ac->msg, "msDS-IntId")) {
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	/* do not generate msDS-IntId if Relax control is passed */
	if (ldb_request_get_control(ac->req, LDB_CONTROL_RELAX_OID)) {
		return LDB_SUCCESS;
	}

	/* check Functional Level */
	if (dsdb_functional_level(ldb) < DS_DOMAIN_FUNCTION_2003) {
		return LDB_SUCCESS;
	}

	/* check systemFlags for SCHEMA_BASE_OBJECT flag */
	system_flags = ldb_msg_find_attr_as_int(ac->msg, "systemFlags", 0);
	if (system_flags & SYSTEM_FLAG_SCHEMA_BASE_OBJECT) {
		return LDB_SUCCESS;
	}
	schema = dsdb_get_schema(ldb, NULL);
	if (!schema) {
		ldb_debug_set(ldb, LDB_DEBUG_FATAL,
			      "samldb_schema_info_update: no dsdb_schema loaded");
		DEBUG(0,(__location__ ": %s\n", ldb_errstring(ldb)));
		return ldb_operr(ldb);
	}

	msds_intid_struct = (struct samldb_msds_intid_persistant*) ldb_get_opaque(ldb, SAMLDB_MSDS_INTID_OPAQUE);
	if (!msds_intid_struct) {
		msds_intid_struct = talloc(ldb, struct samldb_msds_intid_persistant);
		/* Generate new value for msDs-IntId
		* Value should be in 0x80000000..0xBFFFFFFF range */
		msds_intid = generate_random() % 0X3FFFFFFF;
		msds_intid += 0x80000000;
		msds_intid_struct->msds_intid = msds_intid;
		DEBUG(2, ("No samldb_msds_intid_persistant struct, allocating a new one\n"));
	} else {
		msds_intid = msds_intid_struct->msds_intid;
	}

	/* probe id values until unique one is found */
	do {
		msds_intid++;
		if (msds_intid > 0xBFFFFFFF) {
			msds_intid = 0x80000001;
		}
		/*
		 * We search in the schema if we have already this
		 * intid (using dsdb_attribute_by_attributeID_id
		 * because in the range 0x80000000 0xBFFFFFFF,
		 * attributeID is a DSDB_ATTID_TYPE_INTID).
		 *
		 * If so generate another random value.
		 *
		 * We have to check the DB in case someone else has
		 * modified the database while we are doing our
		 * changes too (this case should be very very rare) in
		 * order to be sure.
		 */
		if (dsdb_attribute_by_attributeID_id(schema, msds_intid)) {
			id_exists = true;
			msds_intid = generate_random() % 0X3FFFFFFF;
			msds_intid += 0x80000000;
			continue;
		}


		ret = dsdb_module_search(ac->module, ac,
					 &ldb_res,
					 schema_dn, LDB_SCOPE_ONELEVEL, NULL,
					 DSDB_FLAG_NEXT_MODULE,
					 ac->req,
					 "(msDS-IntId=%d)", msds_intid);
		if (ret != LDB_SUCCESS) {
			ldb_debug_set(ldb, LDB_DEBUG_ERROR,
				      __location__": Searching for msDS-IntId=%d failed - %s\n",
				      msds_intid,
				      ldb_errstring(ldb));
			return ldb_operr(ldb);
		}
		id_exists = (ldb_res->count > 0);
		talloc_free(ldb_res);

	} while(id_exists);
	msds_intid_struct->msds_intid = msds_intid;
	ldb_set_opaque(ldb, SAMLDB_MSDS_INTID_OPAQUE, msds_intid_struct);

	return samdb_msg_add_int(ldb, ac->msg, ac->msg, "msDS-IntId",
				 msds_intid);
}


/*
 * samldb_add_entry (async)
 */

static int samldb_add_entry_callback(struct ldb_request *req,
					struct ldb_reply *ares)
{
	struct ldb_context *ldb;
	struct samldb_ctx *ac;
	int ret;

	ac = talloc_get_type(req->context, struct samldb_ctx);
	ldb = ldb_module_get_ctx(ac->module);

	if (!ares) {
		return ldb_module_done(ac->req, NULL, NULL,
					LDB_ERR_OPERATIONS_ERROR);
	}

	if (ares->type == LDB_REPLY_REFERRAL) {
		return ldb_module_send_referral(ac->req, ares->referral);
	}

	if (ares->error != LDB_SUCCESS) {
		return ldb_module_done(ac->req, ares->controls,
					ares->response, ares->error);
	}
	if (ares->type != LDB_REPLY_DONE) {
		ldb_asprintf_errstring(ldb, "Invalid LDB reply type %d", ares->type);
		return ldb_module_done(ac->req, NULL, NULL,
					LDB_ERR_OPERATIONS_ERROR);
	}

	/* The caller may wish to get controls back from the add */
	ac->ares = talloc_steal(ac, ares);

	ret = samldb_next_step(ac);
	if (ret != LDB_SUCCESS) {
		return ldb_module_done(ac->req, NULL, NULL, ret);
	}
	return ret;
}

static int samldb_add_entry(struct samldb_ctx *ac)
{
	struct ldb_context *ldb;
	struct ldb_request *req;
	int ret;

	ldb = ldb_module_get_ctx(ac->module);

	ret = ldb_build_add_req(&req, ldb, ac,
				ac->msg,
				ac->req->controls,
				ac, samldb_add_entry_callback,
				ac->req);
	LDB_REQ_SET_LOCATION(req);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	return ldb_next_request(ac->module, req);
}

/*
 * return true if msg carries an attributeSchema that is intended to be RODC
 * filtered but is also a system-critical attribute.
 */
static bool check_rodc_critical_attribute(struct ldb_message *msg)
{
	uint32_t schemaFlagsEx, searchFlags, rodc_filtered_flags;

	schemaFlagsEx = ldb_msg_find_attr_as_uint(msg, "schemaFlagsEx", 0);
	searchFlags = ldb_msg_find_attr_as_uint(msg, "searchFlags", 0);
	rodc_filtered_flags = (SEARCH_FLAG_RODC_ATTRIBUTE
			      | SEARCH_FLAG_CONFIDENTIAL);

	if ((schemaFlagsEx & SCHEMA_FLAG_ATTR_IS_CRITICAL) &&
		((searchFlags & rodc_filtered_flags) == rodc_filtered_flags)) {
		return true;
	} else {
		return false;
	}
}


static int samldb_fill_object(struct samldb_ctx *ac)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	int ret;

	/* Add information for the different account types */
	switch(ac->type) {
	case SAMLDB_TYPE_USER: {
		struct ldb_control *rodc_control = ldb_request_get_control(ac->req,
									   LDB_CONTROL_RODC_DCPROMO_OID);
		if (rodc_control != NULL) {
			/* see [MS-ADTS] 3.1.1.3.4.1.23 LDAP_SERVER_RODC_DCPROMO_OID */
			rodc_control->critical = false;
			ret = samldb_add_step(ac, samldb_rodc_add);
			if (ret != LDB_SUCCESS) return ret;
		}

		/* check if we have a valid sAMAccountName */
		ret = samldb_add_step(ac, samldb_check_sAMAccountName);
		if (ret != LDB_SUCCESS) return ret;

		ret = samldb_add_step(ac, samldb_add_entry);
		if (ret != LDB_SUCCESS) return ret;
		break;
	}

	case SAMLDB_TYPE_GROUP: {
		/* check if we have a valid sAMAccountName */
		ret = samldb_add_step(ac, samldb_check_sAMAccountName);
		if (ret != LDB_SUCCESS) return ret;

		ret = samldb_add_step(ac, samldb_add_entry);
		if (ret != LDB_SUCCESS) return ret;
		break;
	}

	case SAMLDB_TYPE_CLASS: {
		const char *lDAPDisplayName = NULL;
		const struct ldb_val *rdn_value, *def_obj_cat_val;
		unsigned int v = ldb_msg_find_attr_as_uint(ac->msg, "objectClassCategory", -2);

		/* As discussed with Microsoft through dochelp in April 2012 this is the behavior of windows*/
		if (!ldb_msg_find_element(ac->msg, "subClassOf")) {
			ret = ldb_msg_add_string(ac->msg, "subClassOf", "top");
			if (ret != LDB_SUCCESS) return ret;
		}

		ret = samdb_find_or_add_attribute(ldb, ac->msg,
						  "rdnAttId", "cn");
		if (ret != LDB_SUCCESS) return ret;

		/* do not allow one to mark an attributeSchema as RODC filtered if it
		 * is system-critical */
		if (check_rodc_critical_attribute(ac->msg)) {
			ldb_asprintf_errstring(ldb, "Refusing schema add of %s - cannot combine critical class with RODC filtering",
					       ldb_dn_get_linearized(ac->msg->dn));
			return LDB_ERR_UNWILLING_TO_PERFORM;
		}

		rdn_value = ldb_dn_get_rdn_val(ac->msg->dn);
		if (rdn_value == NULL) {
			return ldb_operr(ldb);
		}
		if (!ldb_msg_find_element(ac->msg, "lDAPDisplayName")) {
			/* the RDN has prefix "CN" */
			ret = ldb_msg_add_string(ac->msg, "lDAPDisplayName",
				samdb_cn_to_lDAPDisplayName(ac->msg,
							    (const char *) rdn_value->data));
			if (ret != LDB_SUCCESS) {
				ldb_oom(ldb);
				return ret;
			}
		}

		lDAPDisplayName = ldb_msg_find_attr_as_string(ac->msg,
							      "lDAPDisplayName",
							      NULL);
		ret = ldb_valid_attr_name(lDAPDisplayName);
		if (ret != 1 ||
		    lDAPDisplayName[0] == '*' ||
		    lDAPDisplayName[0] == '@')
		{
			return dsdb_module_werror(ac->module,
						  LDB_ERR_UNWILLING_TO_PERFORM,
						  WERR_DS_INVALID_LDAP_DISPLAY_NAME,
						  "lDAPDisplayName is invalid");
		}

		if (!ldb_msg_find_element(ac->msg, "schemaIDGUID")) {
			struct GUID guid;
			/* a new GUID */
			guid = GUID_random();
			ret = dsdb_msg_add_guid(ac->msg, &guid, "schemaIDGUID");
			if (ret != LDB_SUCCESS) {
				ldb_oom(ldb);
				return ret;
			}
		}

		def_obj_cat_val = ldb_msg_find_ldb_val(ac->msg,
						       "defaultObjectCategory");
		if (def_obj_cat_val != NULL) {
			/* "defaultObjectCategory" has been set by the caller.
			 * Do some checks for consistency.
			 * NOTE: The real constraint check (that
			 * 'defaultObjectCategory' is the DN of the new
			 * objectclass or any parent of it) is still incomplete.
			 * For now we say that 'defaultObjectCategory' is valid
			 * if it exists and it is of objectclass "classSchema".
			 */
			ac->dn = ldb_dn_from_ldb_val(ac, ldb, def_obj_cat_val);
			if (ac->dn == NULL) {
				ldb_set_errstring(ldb,
						  "Invalid DN for 'defaultObjectCategory'!");
				return LDB_ERR_CONSTRAINT_VIOLATION;
			}
		} else {
			/* "defaultObjectCategory" has not been set by the
			 * caller. Use the entry DN for it. */
			ac->dn = ac->msg->dn;

			ret = ldb_msg_add_string(ac->msg, "defaultObjectCategory",
						 ldb_dn_alloc_linearized(ac->msg, ac->dn));
			if (ret != LDB_SUCCESS) {
				ldb_oom(ldb);
				return ret;
			}
		}

		ret = samldb_add_step(ac, samldb_add_entry);
		if (ret != LDB_SUCCESS) return ret;

		/* Now perform the checks for the 'defaultObjectCategory'. The
		 * lookup DN was already saved in "ac->dn" */
		ret = samldb_add_step(ac, samldb_find_for_defaultObjectCategory);
		if (ret != LDB_SUCCESS) return ret;

		/* -2 is not a valid objectClassCategory so it means the attribute wasn't present */
		if (v == -2) {
			/* Windows 2003 does this*/
			ret = samdb_msg_add_uint(ldb, ac->msg, ac->msg, "objectClassCategory", 0);
			if (ret != LDB_SUCCESS) {
				return ret;
			}
		}
		break;
	}

	case SAMLDB_TYPE_ATTRIBUTE: {
		const char *lDAPDisplayName = NULL;
		const struct ldb_val *rdn_value;
		struct ldb_message_element *el;
		rdn_value = ldb_dn_get_rdn_val(ac->msg->dn);
		if (rdn_value == NULL) {
			return ldb_operr(ldb);
		}
		if (!ldb_msg_find_element(ac->msg, "lDAPDisplayName")) {
			/* the RDN has prefix "CN" */
			ret = ldb_msg_add_string(ac->msg, "lDAPDisplayName",
				samdb_cn_to_lDAPDisplayName(ac->msg,
							    (const char *) rdn_value->data));
			if (ret != LDB_SUCCESS) {
				ldb_oom(ldb);
				return ret;
			}
		}

		lDAPDisplayName = ldb_msg_find_attr_as_string(ac->msg,
							      "lDAPDisplayName",
							      NULL);
		ret = ldb_valid_attr_name(lDAPDisplayName);
		if (ret != 1 ||
		    lDAPDisplayName[0] == '*' ||
		    lDAPDisplayName[0] == '@')
		{
			return dsdb_module_werror(ac->module,
						  LDB_ERR_UNWILLING_TO_PERFORM,
						  WERR_DS_INVALID_LDAP_DISPLAY_NAME,
						  "lDAPDisplayName is invalid");
		}

		/* do not allow one to mark an attributeSchema as RODC filtered if it
		 * is system-critical */
		if (check_rodc_critical_attribute(ac->msg)) {
			ldb_asprintf_errstring(ldb,
					       "samldb: refusing schema add of %s - cannot combine critical attribute with RODC filtering",
					       ldb_dn_get_linearized(ac->msg->dn));
			return LDB_ERR_UNWILLING_TO_PERFORM;
		}

		ret = samdb_find_or_add_attribute(ldb, ac->msg,
						  "isSingleValued", "FALSE");
		if (ret != LDB_SUCCESS) return ret;

		if (!ldb_msg_find_element(ac->msg, "schemaIDGUID")) {
			struct GUID guid;
			/* a new GUID */
			guid = GUID_random();
			ret = dsdb_msg_add_guid(ac->msg, &guid, "schemaIDGUID");
			if (ret != LDB_SUCCESS) {
				ldb_oom(ldb);
				return ret;
			}
		}

		el = ldb_msg_find_element(ac->msg, "attributeSyntax");
		if (el) {
			/*
			 * No need to scream if there isn't as we have code later on
			 * that will take care of it.
			 */
			const struct dsdb_syntax *syntax = find_syntax_map_by_ad_oid((const char *)el->values[0].data);
			if (!syntax) {
				DEBUG(9, ("Can't find dsdb_syntax object for attributeSyntax %s\n",
						(const char *)el->values[0].data));
			} else {
				unsigned int v = ldb_msg_find_attr_as_uint(ac->msg, "oMSyntax", 0);
				const struct ldb_val *val = ldb_msg_find_ldb_val(ac->msg, "oMObjectClass");

				if (v == 0) {
					ret = samdb_msg_add_uint(ldb, ac->msg, ac->msg, "oMSyntax", syntax->oMSyntax);
					if (ret != LDB_SUCCESS) {
						return ret;
					}
				}
				if (!val) {
					struct ldb_val val2 = ldb_val_dup(ldb, &syntax->oMObjectClass);
					if (val2.length > 0) {
						ret = ldb_msg_add_value(ac->msg, "oMObjectClass", &val2, NULL);
						if (ret != LDB_SUCCESS) {
							return ret;
						}
					}
				}
			}
		}

		/* handle msDS-IntID attribute */
		ret = samldb_add_handle_msDS_IntId(ac);
		if (ret != LDB_SUCCESS) return ret;

		ret = samldb_add_step(ac, samldb_add_entry);
		if (ret != LDB_SUCCESS) return ret;
		break;
	}

	default:
		ldb_asprintf_errstring(ldb, "Invalid entry type!");
		return LDB_ERR_OPERATIONS_ERROR;
		break;
	}

	return samldb_first_step(ac);
}

static int samldb_fill_foreignSecurityPrincipal_object(struct samldb_ctx *ac)
{
	struct ldb_context *ldb = NULL;
	const struct ldb_val *rdn_value = NULL;
	struct ldb_message_element *sid_el = NULL;
	struct dom_sid *sid = NULL;
	struct ldb_control *as_system = NULL;
	struct ldb_control *provision = NULL;
	bool allowed = false;
	int ret;

	ldb = ldb_module_get_ctx(ac->module);

	as_system = ldb_request_get_control(ac->req, LDB_CONTROL_AS_SYSTEM_OID);
	if (as_system != NULL) {
		allowed = true;
	}

	provision = ldb_request_get_control(ac->req, LDB_CONTROL_PROVISION_OID);
	if (provision != NULL) {
		allowed = true;
	}

	sid_el = ldb_msg_find_element(ac->msg, "objectSid");

	if (!allowed && sid_el == NULL) {
		return dsdb_module_werror(ac->module,
				LDB_ERR_OBJECT_CLASS_VIOLATION,
				WERR_DS_MISSING_REQUIRED_ATT,
				"objectSid missing on foreignSecurityPrincipal");
	}

	if (!allowed) {
		return dsdb_module_werror(ac->module,
				LDB_ERR_UNWILLING_TO_PERFORM,
				WERR_DS_ILLEGAL_MOD_OPERATION,
				"foreignSecurityPrincipal object not allowed");
	}

	if (sid_el != NULL) {
		sid = samdb_result_dom_sid(ac->msg, ac->msg, "objectSid");
		if (sid == NULL) {
			ldb_set_errstring(ldb,
					  "samldb: invalid objectSid!");
			return LDB_ERR_CONSTRAINT_VIOLATION;
		}
	}

	if (sid == NULL) {
		rdn_value = ldb_dn_get_rdn_val(ac->msg->dn);
		if (rdn_value == NULL) {
			return ldb_operr(ldb);
		}
		sid = dom_sid_parse_talloc(ac->msg,
					   (const char *)rdn_value->data);
		if (sid == NULL) {
			ldb_set_errstring(ldb,
					  "samldb: No valid SID found in ForeignSecurityPrincipal CN!");
			return LDB_ERR_CONSTRAINT_VIOLATION;
		}
		if (! samldb_msg_add_sid(ac->msg, "objectSid", sid)) {
			return ldb_operr(ldb);
		}
	}

	/* finally proceed with adding the entry */
	ret = samldb_add_step(ac, samldb_add_entry);
	if (ret != LDB_SUCCESS) return ret;

	return samldb_first_step(ac);
}

static int samldb_schema_info_update(struct samldb_ctx *ac)
{
	int ret;
	struct ldb_context *ldb;
	struct dsdb_schema *schema;

	/* replicated update should always go through */
	if (ldb_request_get_control(ac->req,
				    DSDB_CONTROL_REPLICATED_UPDATE_OID)) {
		return LDB_SUCCESS;
	}

	/* do not update schemaInfo during provisioning */
	if (ldb_request_get_control(ac->req, LDB_CONTROL_PROVISION_OID)) {
		return LDB_SUCCESS;
	}

	ldb = ldb_module_get_ctx(ac->module);
	schema = dsdb_get_schema(ldb, NULL);
	if (!schema) {
		ldb_debug_set(ldb, LDB_DEBUG_FATAL,
			      "samldb_schema_info_update: no dsdb_schema loaded");
		DEBUG(0,(__location__ ": %s\n", ldb_errstring(ldb)));
		return ldb_operr(ldb);
	}

	ret = dsdb_module_schema_info_update(ac->module, schema,
					     DSDB_FLAG_NEXT_MODULE|
					     DSDB_FLAG_AS_SYSTEM,
					     ac->req);
	if (ret != LDB_SUCCESS) {
		ldb_asprintf_errstring(ldb,
				       "samldb_schema_info_update: dsdb_module_schema_info_update failed with %s",
				       ldb_errstring(ldb));
		return ret;
	}

	return LDB_SUCCESS;
}

static int samldb_prim_group_tester(struct samldb_ctx *ac, uint32_t rid);
static int samldb_check_user_account_control_rules(struct samldb_ctx *ac,
						   struct dom_sid *sid,
						   uint32_t req_uac,
						   uint32_t user_account_control,
						   uint32_t user_account_control_old,
						   bool is_computer_objectclass);

/*
 * "Objectclass" trigger (MS-SAMR 3.1.1.8.1)
 *
 * Has to be invoked on "add" operations on "user", "computer" and
 * "group" objects.
 * ac->msg contains the "add"
 * ac->type contains the object type (main objectclass)
 */
static int samldb_objectclass_trigger(struct samldb_ctx *ac)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	void *skip_allocate_sids = ldb_get_opaque(ldb,
						  "skip_allocate_sids");
	struct ldb_message_element *el;
	struct dom_sid *sid;
	int ret;

	/* make sure that "sAMAccountType" is not specified */
	el = ldb_msg_find_element(ac->msg, "sAMAccountType");
	if (el != NULL) {
		ldb_set_errstring(ldb,
				  "samldb: sAMAccountType must not be specified!");
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	/* Step 1: objectSid assignment */

	/* Don't allow the objectSid to be changed. But beside the RELAX
	 * control we have also to guarantee that it can always be set with
	 * SYSTEM permissions. This is needed for the "samba3sam" backend. */
	sid = samdb_result_dom_sid(ac, ac->msg, "objectSid");
	if ((sid != NULL) && (!dsdb_module_am_system(ac->module)) &&
	    (ldb_request_get_control(ac->req, LDB_CONTROL_RELAX_OID) == NULL)) {
		ldb_set_errstring(ldb,
				  "samldb: objectSid must not be specified!");
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	/* but generate a new SID when we do have an add operations */
	if ((sid == NULL) && (ac->req->operation == LDB_ADD) && !skip_allocate_sids) {
		ret = samldb_add_step(ac, samldb_allocate_sid);
		if (ret != LDB_SUCCESS) return ret;
	}

	switch(ac->type) {
	case SAMLDB_TYPE_USER: {
		uint32_t raw_uac;
		uint32_t user_account_control;
		bool is_computer_objectclass;
		bool uac_generated = false, uac_add_flags = false;
		uint32_t default_user_account_control = UF_NORMAL_ACCOUNT;
		/* Step 1.2: Default values */
		ret = dsdb_user_obj_set_defaults(ldb, ac->msg, ac->req);
		if (ret != LDB_SUCCESS) return ret;

		is_computer_objectclass
			= (samdb_find_attribute(ldb,
						 ac->msg,
						"objectclass",
						"computer")
			   != NULL);

		if (is_computer_objectclass) {
			default_user_account_control
				= UF_WORKSTATION_TRUST_ACCOUNT;
		}


		/* On add operations we might need to generate a
		 * "userAccountControl" (if it isn't specified). */
		el = ldb_msg_find_element(ac->msg, "userAccountControl");
		if (el == NULL) {
			ret = samdb_msg_set_uint(ldb, ac->msg, ac->msg,
						 "userAccountControl",
						 default_user_account_control);
			if (ret != LDB_SUCCESS) {
				return ret;
			}
			uac_generated = true;
			uac_add_flags = true;
		}

		el = ldb_msg_find_element(ac->msg, "userAccountControl");
		SMB_ASSERT(el != NULL);

		/* Step 1.3: "userAccountControl" -> "sAMAccountType" mapping */
		user_account_control = ldb_msg_find_attr_as_uint(ac->msg,
								 "userAccountControl",
								 0);
		raw_uac = user_account_control;
		/*
		 * "userAccountControl" = 0 or missing one of
		 * the types means "UF_NORMAL_ACCOUNT"
		 * or "UF_WORKSTATION_TRUST_ACCOUNT" (if a computer).
		 * See MS-SAMR 3.1.1.8.10 point 8
		 */
		if ((user_account_control & UF_ACCOUNT_TYPE_MASK) == 0) {
			user_account_control
				= default_user_account_control
				| user_account_control;
			uac_generated = true;
		}

		/*
		 * As per MS-SAMR 3.1.1.8.10 these flags have not to be set
		 */
		if ((user_account_control & UF_LOCKOUT) != 0) {
			user_account_control &= ~UF_LOCKOUT;
			uac_generated = true;
		}
		if ((user_account_control & UF_PASSWORD_EXPIRED) != 0) {
			user_account_control &= ~UF_PASSWORD_EXPIRED;
			uac_generated = true;
		}

		ret = samldb_check_user_account_control_rules(ac, NULL,
							      raw_uac,
							      user_account_control,
							      0,
							      is_computer_objectclass);
		if (ret != LDB_SUCCESS) {
			return ret;
		}

		/*
		 * Require, for non-admin modifications, a trailing $
		 * for either objectclass=computer or a trust account
		 * type in userAccountControl
		 */
		if ((user_account_control
		     & UF_TRUST_ACCOUNT_MASK) != 0) {
			ac->need_trailing_dollar = true;
		}

		if (is_computer_objectclass) {
			ac->need_trailing_dollar = true;
		}

		/* add "sAMAccountType" attribute */
		ret = dsdb_user_obj_set_account_type(ldb, ac->msg, user_account_control, NULL);
		if (ret != LDB_SUCCESS) {
			return ret;
		}

		/* "isCriticalSystemObject" might be set */
		if (user_account_control &
		    (UF_SERVER_TRUST_ACCOUNT | UF_PARTIAL_SECRETS_ACCOUNT)) {
			ret = ldb_msg_add_string_flags(ac->msg, "isCriticalSystemObject",
						       "TRUE", LDB_FLAG_MOD_REPLACE);
			if (ret != LDB_SUCCESS) {
				return ret;
			}
		} else if (user_account_control & UF_WORKSTATION_TRUST_ACCOUNT) {
			ret = ldb_msg_add_string_flags(ac->msg, "isCriticalSystemObject",
						       "FALSE", LDB_FLAG_MOD_REPLACE);
			if (ret != LDB_SUCCESS) {
				return ret;
			}
		}

		/* Step 1.4: "userAccountControl" -> "primaryGroupID" mapping */
		if (!ldb_msg_find_element(ac->msg, "primaryGroupID")) {
			uint32_t rid;

			ret = dsdb_user_obj_set_primary_group_id(ldb, ac->msg, user_account_control, &rid);
			if (ret != LDB_SUCCESS) {
				return ret;
			}
			/*
			 * Older AD deployments don't know about the
			 * RODC group
			 */
			if (rid == DOMAIN_RID_READONLY_DCS) {
				ret = samldb_prim_group_tester(ac, rid);
				if (ret != LDB_SUCCESS) {
					return ret;
				}
			}
		}

		/* Step 1.5: Add additional flags when needed */
		/* Obviously this is done when the "userAccountControl"
		 * has been generated here (tested against Windows
		 * Server) */
		if (uac_generated) {
			if (uac_add_flags) {
				user_account_control |= UF_ACCOUNTDISABLE;
				user_account_control |= UF_PASSWD_NOTREQD;
			}

			ret = samdb_msg_set_uint(ldb, ac->msg, ac->msg,
						 "userAccountControl",
						 user_account_control);
			if (ret != LDB_SUCCESS) {
				return ret;
			}
		}
		break;
	}

	case SAMLDB_TYPE_GROUP: {
		const char *tempstr;

		/* Step 2.2: Default values */
		tempstr = talloc_asprintf(ac->msg, "%d",
					  GTYPE_SECURITY_GLOBAL_GROUP);
		if (tempstr == NULL) return ldb_operr(ldb);
		ret = samdb_find_or_add_attribute(ldb, ac->msg,
			"groupType", tempstr);
		if (ret != LDB_SUCCESS) return ret;

		/* Step 2.3: "groupType" -> "sAMAccountType" */
		el = ldb_msg_find_element(ac->msg, "groupType");
		if (el != NULL) {
			uint32_t group_type, account_type;

			group_type = ldb_msg_find_attr_as_uint(ac->msg,
							       "groupType", 0);

			/* The creation of builtin groups requires the
			 * RELAX control */
			if (group_type == GTYPE_SECURITY_BUILTIN_LOCAL_GROUP) {
				if (ldb_request_get_control(ac->req,
							    LDB_CONTROL_RELAX_OID) == NULL) {
					return LDB_ERR_UNWILLING_TO_PERFORM;
				}
			}

			account_type = ds_gtype2atype(group_type);
			if (account_type == 0) {
				ldb_set_errstring(ldb, "samldb: Unrecognized account type!");
				return LDB_ERR_UNWILLING_TO_PERFORM;
			}
			ret = samdb_msg_add_uint_flags(ldb, ac->msg, ac->msg,
						       "sAMAccountType",
						       account_type,
						       LDB_FLAG_MOD_REPLACE);
			if (ret != LDB_SUCCESS) {
				return ret;
			}
		}
		break;
	}

	default:
		ldb_asprintf_errstring(ldb,
				"Invalid entry type!");
		return LDB_ERR_OPERATIONS_ERROR;
		break;
	}

	return LDB_SUCCESS;
}

/*
 * "Primary group ID" trigger (MS-SAMR 3.1.1.8.2)
 *
 * Has to be invoked on "add" and "modify" operations on "user" and "computer"
 * objects.
 * ac->msg contains the "add"/"modify" message
 */

static int samldb_prim_group_tester(struct samldb_ctx *ac, uint32_t rid)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	struct dom_sid *sid;
	struct ldb_result *res;
	int ret;
	const char * const noattrs[] = { NULL };

	sid = dom_sid_add_rid(ac, samdb_domain_sid(ldb), rid);
	if (sid == NULL) {
		return ldb_operr(ldb);
	}

	ret = dsdb_module_search(ac->module, ac, &res,
				 ldb_get_default_basedn(ldb),
				 LDB_SCOPE_SUBTREE,
				 noattrs, DSDB_FLAG_NEXT_MODULE,
				 ac->req,
				 "(objectSid=%s)",
				 ldap_encode_ndr_dom_sid(ac, sid));
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	if (res->count != 1) {
		talloc_free(res);
		ldb_asprintf_errstring(ldb,
				       "Failed to find primary group with RID %u!",
				       rid);
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}
	talloc_free(res);

	return LDB_SUCCESS;
}

static int samldb_prim_group_set(struct samldb_ctx *ac)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	uint32_t rid;

	rid = ldb_msg_find_attr_as_uint(ac->msg, "primaryGroupID", (uint32_t) -1);
	if (rid == (uint32_t) -1) {
		/* we aren't affected of any primary group set */
		return LDB_SUCCESS;

	} else if (!ldb_request_get_control(ac->req, LDB_CONTROL_RELAX_OID)) {
		ldb_set_errstring(ldb,
				  "The primary group isn't settable on add operations!");
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	return samldb_prim_group_tester(ac, rid);
}

static int samldb_prim_group_change(struct samldb_ctx *ac)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	const char * const attrs[] = {
		"primaryGroupID",
		"memberOf",
		"userAccountControl",
		NULL };
	struct ldb_result *res, *group_res;
	struct ldb_message_element *el;
	struct ldb_message *msg;
	uint32_t search_flags =
		DSDB_FLAG_NEXT_MODULE | DSDB_SEARCH_SHOW_EXTENDED_DN;
	uint32_t prev_rid, new_rid, uac;
	struct dom_sid *prev_sid, *new_sid;
	struct ldb_dn *prev_prim_group_dn, *new_prim_group_dn;
	const char *new_prim_group_dn_ext_str = NULL;
	struct ldb_dn *user_dn = NULL;
	const char *user_dn_ext_str = NULL;
	int ret;
	const char * const noattrs[] = { NULL };
	const char * const group_type_attrs[] = { "groupType", NULL };
	unsigned group_type;

	ret = dsdb_get_expected_new_values(ac,
					   ac->msg,
					   "primaryGroupID",
					   &el,
					   ac->req->operation);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	if (el == NULL) {
		/* we are not affected */
		return LDB_SUCCESS;
	}

	/* Fetch information from the existing object */

	ret = dsdb_module_search_dn(ac->module, ac, &res, ac->msg->dn, attrs,
				    search_flags, ac->req);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	user_dn = res->msgs[0]->dn;
	user_dn_ext_str = ldb_dn_get_extended_linearized(ac, user_dn, 1);
	if (user_dn_ext_str == NULL) {
		return ldb_operr(ldb);
	}

	uac = ldb_msg_find_attr_as_uint(res->msgs[0], "userAccountControl", 0);

	/* Finds out the DN of the old primary group */

	prev_rid = ldb_msg_find_attr_as_uint(res->msgs[0], "primaryGroupID",
					     (uint32_t) -1);
	if (prev_rid == (uint32_t) -1) {
		/* User objects do always have a mandatory "primaryGroupID"
		 * attribute. If this doesn't exist then the object is of the
		 * wrong type. This is the exact Windows error code */
		return LDB_ERR_OBJECT_CLASS_VIOLATION;
	}

	prev_sid = dom_sid_add_rid(ac, samdb_domain_sid(ldb), prev_rid);
	if (prev_sid == NULL) {
		return ldb_operr(ldb);
	}

	/* Finds out the DN of the new primary group
	 * Notice: in order to parse the primary group ID correctly we create
	 * a temporary message here. */

	msg = ldb_msg_new(ac->msg);
	if (msg == NULL) {
		return ldb_module_oom(ac->module);
	}
	ret = ldb_msg_add(msg, el, 0);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	new_rid = ldb_msg_find_attr_as_uint(msg, "primaryGroupID", (uint32_t) -1);
	talloc_free(msg);
	if (new_rid == (uint32_t) -1) {
		/* we aren't affected of any primary group change */
		return LDB_SUCCESS;
	}

	if (prev_rid == new_rid) {
		return LDB_SUCCESS;
	}

	if ((uac & UF_SERVER_TRUST_ACCOUNT) && new_rid != DOMAIN_RID_DCS) {
		ldb_asprintf_errstring(ldb,
			"%08X: samldb: UF_SERVER_TRUST_ACCOUNT requires "
			"primaryGroupID=%u!",
			W_ERROR_V(WERR_DS_CANT_MOD_PRIMARYGROUPID),
			DOMAIN_RID_DCS);
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	if ((uac & UF_PARTIAL_SECRETS_ACCOUNT) && new_rid != DOMAIN_RID_READONLY_DCS) {
		ldb_asprintf_errstring(ldb,
			"%08X: samldb: UF_PARTIAL_SECRETS_ACCOUNT requires "
			"primaryGroupID=%u!",
			W_ERROR_V(WERR_DS_CANT_MOD_PRIMARYGROUPID),
			DOMAIN_RID_READONLY_DCS);
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	ret = dsdb_module_search(ac->module, ac, &group_res,
				 ldb_get_default_basedn(ldb),
				 LDB_SCOPE_SUBTREE,
				 noattrs, search_flags,
				 ac->req,
				 "(objectSid=%s)",
				 ldap_encode_ndr_dom_sid(ac, prev_sid));
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	if (group_res->count != 1) {
		return ldb_operr(ldb);
	}
	prev_prim_group_dn = group_res->msgs[0]->dn;

	new_sid = dom_sid_add_rid(ac, samdb_domain_sid(ldb), new_rid);
	if (new_sid == NULL) {
		return ldb_operr(ldb);
	}

	ret = dsdb_module_search(ac->module, ac, &group_res,
				 ldb_get_default_basedn(ldb),
				 LDB_SCOPE_SUBTREE,
				 group_type_attrs, search_flags,
				 ac->req,
				 "(objectSid=%s)",
				 ldap_encode_ndr_dom_sid(ac, new_sid));
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	if (group_res->count != 1) {
		/* Here we know if the specified new primary group candidate is
		 * valid or not. */
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}
	new_prim_group_dn = group_res->msgs[0]->dn;

	/* The new primary group must not be domain-local. */
	group_type = ldb_msg_find_attr_as_uint(group_res->msgs[0], "groupType", 0);
	if (group_type & GROUP_TYPE_RESOURCE_GROUP) {
		return dsdb_module_werror(ac->module,
					  LDB_ERR_UNWILLING_TO_PERFORM,
					  WERR_MEMBER_NOT_IN_GROUP,
					  "may not set resource group as primary group!");
	}

	new_prim_group_dn_ext_str = ldb_dn_get_extended_linearized(ac,
							new_prim_group_dn, 1);
	if (new_prim_group_dn_ext_str == NULL) {
		return ldb_operr(ldb);
	}

	/* We need to be already a normal member of the new primary
	 * group in order to be successful. */
	el = samdb_find_attribute(ldb, res->msgs[0], "memberOf",
				  new_prim_group_dn_ext_str);
	if (el == NULL) {
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	/* Remove the "member" attribute on the new primary group */
	msg = ldb_msg_new(ac->msg);
	if (msg == NULL) {
		return ldb_module_oom(ac->module);
	}
	msg->dn = new_prim_group_dn;

	ret = samdb_msg_add_delval(ldb, msg, msg, "member", user_dn_ext_str);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	ret = dsdb_module_modify(ac->module, msg, DSDB_FLAG_NEXT_MODULE, ac->req);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	talloc_free(msg);

	/* Add a "member" attribute for the previous primary group */
	msg = ldb_msg_new(ac->msg);
	if (msg == NULL) {
		return ldb_module_oom(ac->module);
	}
	msg->dn = prev_prim_group_dn;

	ret = samdb_msg_add_addval(ldb, msg, msg, "member", user_dn_ext_str);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	ret = dsdb_module_modify(ac->module, msg, DSDB_FLAG_NEXT_MODULE, ac->req);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	talloc_free(msg);

	return LDB_SUCCESS;
}

static int samldb_prim_group_trigger(struct samldb_ctx *ac)
{
	int ret;

	if (ac->req->operation == LDB_ADD) {
		ret = samldb_prim_group_set(ac);
	} else {
		ret = samldb_prim_group_change(ac);
	}

	return ret;
}

static int samldb_check_user_account_control_invariants(struct samldb_ctx *ac,
						    uint32_t user_account_control)
{
	size_t i;
	int ret = 0;
	bool need_check = false;
	const struct uac_to_guid {
		uint32_t uac;
		bool never;
		uint32_t needs;
		uint32_t not_with;
		const char *error_string;
	} map[] = {
		{
			.uac = UF_TEMP_DUPLICATE_ACCOUNT,
			.never = true,
			.error_string = "Updating the UF_TEMP_DUPLICATE_ACCOUNT flag is never allowed"
		},
		{
			.uac = UF_PARTIAL_SECRETS_ACCOUNT,
			.needs = UF_WORKSTATION_TRUST_ACCOUNT,
			.error_string = "Setting UF_PARTIAL_SECRETS_ACCOUNT only permitted with UF_WORKSTATION_TRUST_ACCOUNT"
		},
		{
			.uac = UF_TRUSTED_FOR_DELEGATION,
			.not_with = UF_PARTIAL_SECRETS_ACCOUNT,
			.error_string = "Setting UF_TRUSTED_FOR_DELEGATION not allowed with UF_PARTIAL_SECRETS_ACCOUNT"
		},
		{
			.uac = UF_NORMAL_ACCOUNT,
			.not_with = UF_ACCOUNT_TYPE_MASK & ~UF_NORMAL_ACCOUNT,
			.error_string = "Setting more than one account type not permitted"
		},
		{
			.uac = UF_WORKSTATION_TRUST_ACCOUNT,
			.not_with = UF_ACCOUNT_TYPE_MASK & ~UF_WORKSTATION_TRUST_ACCOUNT,
			.error_string = "Setting more than one account type not permitted"
		},
		{
			.uac = UF_INTERDOMAIN_TRUST_ACCOUNT,
			.not_with = UF_ACCOUNT_TYPE_MASK & ~UF_INTERDOMAIN_TRUST_ACCOUNT,
			.error_string = "Setting more than one account type not permitted"
		},
		{
			.uac = UF_SERVER_TRUST_ACCOUNT,
			.not_with = UF_ACCOUNT_TYPE_MASK & ~UF_SERVER_TRUST_ACCOUNT,
			.error_string = "Setting more than one account type not permitted"
		},
		{
			.uac = UF_TRUSTED_FOR_DELEGATION,
			.not_with = UF_PARTIAL_SECRETS_ACCOUNT,
			.error_string = "Setting UF_TRUSTED_FOR_DELEGATION not allowed with UF_PARTIAL_SECRETS_ACCOUNT"
		}
	};

	for (i = 0; i < ARRAY_SIZE(map); i++) {
		if (user_account_control & map[i].uac) {
			need_check = true;
			break;
		}
	}
	if (need_check == false) {
		return LDB_SUCCESS;
	}

	for (i = 0; i < ARRAY_SIZE(map); i++) {
		uint32_t this_uac = user_account_control & map[i].uac;
		if (this_uac != 0) {
			if (map[i].never) {
				ret = LDB_ERR_OTHER;
				break;
			} else if (map[i].needs != 0) {
				if ((map[i].needs & user_account_control) == 0) {
					ret = LDB_ERR_OTHER;
					break;
				}
			} else if (map[i].not_with != 0) {
				if ((map[i].not_with & user_account_control) != 0) {
					ret = LDB_ERR_OTHER;
					break;
				}
			}
		}
	}
	if (ret != LDB_SUCCESS) {
		switch (ac->req->operation) {
		case LDB_ADD:
			ldb_asprintf_errstring(ldb_module_get_ctx(ac->module),
					       "Failed to add %s: %s",
					       ldb_dn_get_linearized(ac->msg->dn),
					       map[i].error_string);
			break;
		case LDB_MODIFY:
			ldb_asprintf_errstring(ldb_module_get_ctx(ac->module),
					       "Failed to modify %s: %s",
					       ldb_dn_get_linearized(ac->msg->dn),
					       map[i].error_string);
			break;
		default:
			return ldb_module_operr(ac->module);
		}
	}
	return ret;
}

/*
 * It would be best if these rules apply, always, but for now they
 * apply only to non-admins
 */
static int samldb_check_user_account_control_objectclass_invariants(
	struct samldb_ctx *ac,
	uint32_t user_account_control,
	uint32_t user_account_control_old,
	bool is_computer_objectclass)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);

	uint32_t old_ufa = user_account_control_old & UF_ACCOUNT_TYPE_MASK;
	uint32_t new_ufa = user_account_control & UF_ACCOUNT_TYPE_MASK;

	uint32_t old_rodc = user_account_control_old & UF_PARTIAL_SECRETS_ACCOUNT;
	uint32_t new_rodc = user_account_control & UF_PARTIAL_SECRETS_ACCOUNT;

	bool is_admin;
	struct security_token *user_token
		= acl_user_token(ac->module);
	if (user_token == NULL) {
		return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
	}

	is_admin
		= security_token_has_builtin_administrators(user_token);


	/*
	 * We want to allow changes to (eg) disable an account
	 * that was created wrong, only checking the
	 * objectclass if the account type changes.
	 */
	if (old_ufa == new_ufa && old_rodc == new_rodc) {
		return LDB_SUCCESS;
	}

	switch (new_ufa) {
	case UF_NORMAL_ACCOUNT:
		if (is_computer_objectclass && !is_admin) {
			ldb_asprintf_errstring(ldb,
				"%08X: samldb: UF_NORMAL_ACCOUNT "
				"requires objectclass 'user' not 'computer'!",
				W_ERROR_V(WERR_DS_MACHINE_ACCOUNT_CREATED_PRENT4));
			return LDB_ERR_OBJECT_CLASS_VIOLATION;
		}
		break;

	case UF_INTERDOMAIN_TRUST_ACCOUNT:
		if (is_computer_objectclass) {
			ldb_asprintf_errstring(ldb,
				"%08X: samldb: UF_INTERDOMAIN_TRUST_ACCOUNT "
				"requires objectclass 'user' not 'computer'!",
				W_ERROR_V(WERR_DS_MACHINE_ACCOUNT_CREATED_PRENT4));
			return LDB_ERR_OBJECT_CLASS_VIOLATION;
		}
		break;

	case UF_WORKSTATION_TRUST_ACCOUNT:
		if (!is_computer_objectclass) {
			/*
			 * Modify of a user account account into a
			 * workstation without objectclass computer
			 * as an admin is still permitted, but not
			 * to make an RODC
			 */
			if (is_admin
			    && ac->req->operation == LDB_MODIFY
			    && new_rodc == 0) {
				break;
			}
			ldb_asprintf_errstring(ldb,
				"%08X: samldb: UF_WORKSTATION_TRUST_ACCOUNT "
				"requires objectclass 'computer'!",
				W_ERROR_V(WERR_DS_MACHINE_ACCOUNT_CREATED_PRENT4));
			return LDB_ERR_OBJECT_CLASS_VIOLATION;
		}
		break;

	case UF_SERVER_TRUST_ACCOUNT:
		if (!is_computer_objectclass) {
			ldb_asprintf_errstring(ldb,
				"%08X: samldb: UF_SERVER_TRUST_ACCOUNT "
				"requires objectclass 'computer'!",
				W_ERROR_V(WERR_DS_MACHINE_ACCOUNT_CREATED_PRENT4));
			return LDB_ERR_OBJECT_CLASS_VIOLATION;
		}
		break;

	default:
		ldb_asprintf_errstring(ldb,
			"%08X: samldb: invalid userAccountControl[0x%08X]",
			W_ERROR_V(WERR_INVALID_PARAMETER),
				       user_account_control);
		return LDB_ERR_OTHER;
	}
	return LDB_SUCCESS;
}

static int samldb_get_domain_secdesc_and_oc(struct samldb_ctx *ac,
					    struct security_descriptor **domain_sd,
					    const struct dsdb_class **objectclass)
{
	const char * const sd_attrs[] = {"ntSecurityDescriptor", "objectClass", NULL};
	struct ldb_result *res;
	struct ldb_dn *domain_dn = ldb_get_default_basedn(ldb_module_get_ctx(ac->module));
	const struct dsdb_schema *schema = NULL;
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	int ret = dsdb_module_search_dn(ac->module, ac, &res,
					domain_dn,
					sd_attrs,
					DSDB_FLAG_NEXT_MODULE | DSDB_SEARCH_SHOW_DELETED,
					ac->req);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	if (res->count != 1) {
		return ldb_module_operr(ac->module);
	}

	schema = dsdb_get_schema(ldb, ac->req);
	if (!schema) {
		return ldb_module_operr(ac->module);;
	}
	*objectclass = dsdb_get_structural_oc_from_msg(schema, res->msgs[0]);
	return dsdb_get_sd_from_ldb_message(ldb_module_get_ctx(ac->module),
					    ac, res->msgs[0], domain_sd);

}

/**
 * Validate that the restriction in point 5 of MS-SAMR 3.1.1.8.10 userAccountControl is honoured
 *
 */
static int samldb_check_user_account_control_acl(struct samldb_ctx *ac,
						 struct dom_sid *sid,
						 uint32_t user_account_control,
						 uint32_t user_account_control_old)
{
	size_t i;
	int ret = 0;
	bool need_acl_check = false;
	struct security_token *user_token;
	struct security_descriptor *domain_sd;
	const struct dsdb_class *objectclass = NULL;
	const struct uac_to_guid {
		uint32_t uac;
		uint32_t priv_to_change_from;
		const char *oid;
		const char *guid;
		enum sec_privilege privilege;
		bool delete_is_privileged;
		bool admin_required;
		const char *error_string;
	} map[] = {
		{
			.uac = UF_PASSWD_NOTREQD,
			.guid = GUID_DRS_UPDATE_PASSWORD_NOT_REQUIRED_BIT,
			.error_string = "Adding the UF_PASSWD_NOTREQD bit in userAccountControl requires the Update-Password-Not-Required-Bit right that was not given on the Domain object"
		},
		{
			.uac = UF_DONT_EXPIRE_PASSWD,
			.guid = GUID_DRS_UNEXPIRE_PASSWORD,
			.error_string = "Adding the UF_DONT_EXPIRE_PASSWD bit in userAccountControl requires the Unexpire-Password right that was not given on the Domain object"
		},
		{
			.uac = UF_ENCRYPTED_TEXT_PASSWORD_ALLOWED,
			.guid = GUID_DRS_ENABLE_PER_USER_REVERSIBLY_ENCRYPTED_PASSWORD,
			.error_string = "Adding the UF_ENCRYPTED_TEXT_PASSWORD_ALLOWED bit in userAccountControl requires the Enable-Per-User-Reversibly-Encrypted-Password right that was not given on the Domain object"
		},
		{
			.uac = UF_SERVER_TRUST_ACCOUNT,
			.guid = GUID_DRS_DS_INSTALL_REPLICA,
			.error_string = "Adding the UF_SERVER_TRUST_ACCOUNT bit in userAccountControl requires the DS-Install-Replica right that was not given on the Domain object"
		},
		{
			.uac = UF_PARTIAL_SECRETS_ACCOUNT,
			.guid = GUID_DRS_DS_INSTALL_REPLICA,
			.error_string = "Adding the UF_PARTIAL_SECRETS_ACCOUNT bit in userAccountControl requires the DS-Install-Replica right that was not given on the Domain object"
		},
		{
			.uac = UF_WORKSTATION_TRUST_ACCOUNT,
			.priv_to_change_from = UF_NORMAL_ACCOUNT,
			.error_string = "Swapping UF_NORMAL_ACCOUNT to UF_WORKSTATION_TRUST_ACCOUNT requires the user to be a member of the domain admins group"
		},
		{
			.uac = UF_NORMAL_ACCOUNT,
			.priv_to_change_from = UF_WORKSTATION_TRUST_ACCOUNT,
			.error_string = "Swapping UF_WORKSTATION_TRUST_ACCOUNT to UF_NORMAL_ACCOUNT requires the user to be a member of the domain admins group"
		},
		{
			.uac = UF_INTERDOMAIN_TRUST_ACCOUNT,
			.oid = DSDB_CONTROL_PERMIT_INTERDOMAIN_TRUST_UAC_OID,
			.error_string = "Updating the UF_INTERDOMAIN_TRUST_ACCOUNT bit in userAccountControl is not permitted over LDAP.  This bit is restricted to the LSA CreateTrustedDomain interface",
			.delete_is_privileged = true
		},
		{
			.uac = UF_TRUSTED_FOR_DELEGATION,
			.privilege = SEC_PRIV_ENABLE_DELEGATION,
			.delete_is_privileged = true,
			.error_string = "Updating the UF_TRUSTED_FOR_DELEGATION bit in userAccountControl is not permitted without the SeEnableDelegationPrivilege"
		},
		{
			.uac = UF_TRUSTED_TO_AUTHENTICATE_FOR_DELEGATION,
			.privilege = SEC_PRIV_ENABLE_DELEGATION,
			.delete_is_privileged = true,
			.error_string = "Updating the UF_TRUSTED_TO_AUTHENTICATE_FOR_DELEGATION bit in userAccountControl is not permitted without the SeEnableDelegationPrivilege"
		}

	};

	if (dsdb_module_am_system(ac->module)) {
		return LDB_SUCCESS;
	}

	for (i = 0; i < ARRAY_SIZE(map); i++) {
		if (user_account_control & map[i].uac) {
			need_acl_check = true;
			break;
		}
	}
	if (need_acl_check == false) {
		return LDB_SUCCESS;
	}

	user_token = acl_user_token(ac->module);
	if (user_token == NULL) {
		return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
	}

	ret = samldb_get_domain_secdesc_and_oc(ac, &domain_sd, &objectclass);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	for (i = 0; i < ARRAY_SIZE(map); i++) {
		uint32_t this_uac_new = user_account_control & map[i].uac;
		uint32_t this_uac_old = user_account_control_old & map[i].uac;
		if (this_uac_new != this_uac_old) {
			if (this_uac_old != 0) {
				if (map[i].delete_is_privileged == false) {
					continue;
				}
			}
			if (map[i].oid) {
				struct ldb_control *control = ldb_request_get_control(ac->req, map[i].oid);
				if (control == NULL) {
					ret = LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
				}
			} else if (map[i].privilege != SEC_PRIV_INVALID) {
				bool have_priv = security_token_has_privilege(user_token,
									      map[i].privilege);
				if (have_priv == false) {
					ret = LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
				}
			} else if (map[i].priv_to_change_from & user_account_control_old) {
				bool is_admin = security_token_has_builtin_administrators(user_token);
				if (is_admin == false) {
					ret = LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
				}
			} else if (map[i].guid) {
				ret = acl_check_extended_right(ac,
							       ac->module,
							       ac->req,
							       objectclass,
							       domain_sd,
							       user_token,
							       map[i].guid,
							       SEC_ADS_CONTROL_ACCESS,
							       sid);
			} else {
				ret = LDB_SUCCESS;
			}
			if (ret != LDB_SUCCESS) {
				break;
			}
		}
	}
	if (ret == LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS) {
		switch (ac->req->operation) {
		case LDB_ADD:
			ldb_asprintf_errstring(ldb_module_get_ctx(ac->module),
					       "Failed to add %s: %s",
					       ldb_dn_get_linearized(ac->msg->dn),
					       map[i].error_string);
			break;
		case LDB_MODIFY:
			ldb_asprintf_errstring(ldb_module_get_ctx(ac->module),
					       "Failed to modify %s: %s",
					       ldb_dn_get_linearized(ac->msg->dn),
					       map[i].error_string);
			break;
		default:
			return ldb_module_operr(ac->module);
		}
		if (map[i].guid) {
			struct ldb_dn *domain_dn
				= ldb_get_default_basedn(ldb_module_get_ctx(ac->module));
			dsdb_acl_debug(domain_sd, acl_user_token(ac->module),
				       domain_dn,
				       true,
				       10);
		}
	}
	return ret;
}

static int samldb_check_user_account_control_rules(struct samldb_ctx *ac,
						   struct dom_sid *sid,
						   uint32_t req_uac,
						   uint32_t user_account_control,
						   uint32_t user_account_control_old,
						   bool is_computer_objectclass)
{
	int ret;
	struct dsdb_control_password_user_account_control *uac = NULL;

	ret = samldb_check_user_account_control_invariants(ac, user_account_control);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	ret = samldb_check_user_account_control_objectclass_invariants(ac,
								       user_account_control,
								       user_account_control_old,
								       is_computer_objectclass);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	ret = samldb_check_user_account_control_acl(ac, sid, user_account_control, user_account_control_old);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	uac = talloc_zero(ac->req,
			  struct dsdb_control_password_user_account_control);
	if (uac == NULL) {
		return ldb_module_oom(ac->module);
	}

	uac->req_flags = req_uac;
	uac->old_flags = user_account_control_old;
	uac->new_flags = user_account_control;

	ret = ldb_request_add_control(ac->req,
				DSDB_CONTROL_PASSWORD_USER_ACCOUNT_CONTROL_OID,
				false, uac);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	return ret;
}


/**
 * This function is called on LDB modify operations. It performs some additions/
 * replaces on the current LDB message when "userAccountControl" changes.
 */
static int samldb_user_account_control_change(struct samldb_ctx *ac)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	uint32_t old_uac;
	uint32_t new_uac;
	uint32_t raw_uac;
	uint32_t old_ufa;
	uint32_t new_ufa;
	uint32_t old_uac_computed;
	uint32_t clear_uac;
	uint32_t old_atype;
	uint32_t new_atype;
	uint32_t old_pgrid;
	uint32_t new_pgrid;
	NTTIME old_lockoutTime;
	struct ldb_message_element *el;
	struct ldb_val *val;
	struct ldb_val computer_val;
	struct ldb_message *tmp_msg;
	struct dom_sid *sid;
	int ret;
	struct ldb_result *res;
	const char * const attrs[] = {
		"objectClass",
		"isCriticalSystemObject",
		"userAccountControl",
		"msDS-User-Account-Control-Computed",
		"lockoutTime",
		"objectSid",
		NULL
	};
	bool is_computer_objectclass = false;
	bool old_is_critical = false;
	bool new_is_critical = false;

	ret = dsdb_get_expected_new_values(ac,
					   ac->msg,
					   "userAccountControl",
					   &el,
					   ac->req->operation);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	if (el == NULL || el->num_values == 0) {
		ldb_asprintf_errstring(ldb,
			"%08X: samldb: 'userAccountControl' can't be deleted!",
			W_ERROR_V(WERR_DS_ILLEGAL_MOD_OPERATION));
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	/* Create a temporary message for fetching the "userAccountControl" */
	tmp_msg = ldb_msg_new(ac->msg);
	if (tmp_msg == NULL) {
		return ldb_module_oom(ac->module);
	}
	ret = ldb_msg_add(tmp_msg, el, 0);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	raw_uac = ldb_msg_find_attr_as_uint(tmp_msg,
					    "userAccountControl",
					    0);
	talloc_free(tmp_msg);
	/*
	 * UF_LOCKOUT, UF_PASSWD_CANT_CHANGE and UF_PASSWORD_EXPIRED
	 * are only generated and not stored. We ignore them almost
	 * completely, along with unknown bits and UF_SCRIPT.
	 *
	 * The only exception is ACB_AUTOLOCK, which features in
	 * clear_acb when the bit is cleared in this modify operation.
	 *
	 * MS-SAMR 2.2.1.13 UF_FLAG Codes states that some bits are
	 * ignored by clients and servers
	 */
	new_uac = raw_uac & UF_SETTABLE_BITS;

	/* Fetch the old "userAccountControl" and "objectClass" */
	ret = dsdb_module_search_dn(ac->module, ac, &res, ac->msg->dn, attrs,
				    DSDB_FLAG_NEXT_MODULE, ac->req);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	old_uac = ldb_msg_find_attr_as_uint(res->msgs[0], "userAccountControl", 0);
	if (old_uac == 0) {
		return ldb_operr(ldb);
	}
	old_uac_computed = ldb_msg_find_attr_as_uint(res->msgs[0],
						     "msDS-User-Account-Control-Computed", 0);
	old_lockoutTime = ldb_msg_find_attr_as_int64(res->msgs[0],
						     "lockoutTime", 0);
	old_is_critical = ldb_msg_find_attr_as_bool(res->msgs[0],
						    "isCriticalSystemObject", 0);
	/*
	 * When we do not have objectclass "computer" we cannot
	 * switch to a workstation or (RO)DC
	 */
	el = ldb_msg_find_element(res->msgs[0], "objectClass");
	if (el == NULL) {
		return ldb_operr(ldb);
	}
	computer_val = data_blob_string_const("computer");
	val = ldb_msg_find_val(el, &computer_val);
	if (val != NULL) {
		is_computer_objectclass = true;
	}

	old_ufa = old_uac & UF_ACCOUNT_TYPE_MASK;
	old_atype = ds_uf2atype(old_ufa);
	old_pgrid = ds_uf2prim_group_rid(old_uac);

	new_ufa = new_uac & UF_ACCOUNT_TYPE_MASK;
	if (new_ufa == 0) {
		/*
		 * "userAccountControl" = 0 or missing one of the
		 * types means "UF_NORMAL_ACCOUNT".  See MS-SAMR
		 * 3.1.1.8.10 point 8
		 */
		new_ufa = UF_NORMAL_ACCOUNT;
		new_uac |= new_ufa;
	}
	sid = samdb_result_dom_sid(res, res->msgs[0], "objectSid");
	if (sid == NULL) {
		return ldb_module_operr(ac->module);
	}

	ret = samldb_check_user_account_control_rules(ac, sid,
						      raw_uac,
						      new_uac,
						      old_uac,
						      is_computer_objectclass);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	new_atype = ds_uf2atype(new_ufa);
	new_pgrid = ds_uf2prim_group_rid(new_uac);

	clear_uac = (old_uac | old_uac_computed) & ~raw_uac;

	switch (new_ufa) {
	case UF_NORMAL_ACCOUNT:
		new_is_critical = old_is_critical;
		break;

	case UF_INTERDOMAIN_TRUST_ACCOUNT:
		new_is_critical = true;
		break;

	case UF_WORKSTATION_TRUST_ACCOUNT:
		new_is_critical = false;
		if (new_uac & UF_PARTIAL_SECRETS_ACCOUNT) {
			new_is_critical = true;
		}
		break;

	case UF_SERVER_TRUST_ACCOUNT:
		new_is_critical = true;
		break;

	default:
		ldb_asprintf_errstring(ldb,
			"%08X: samldb: invalid userAccountControl[0x%08X]",
			W_ERROR_V(WERR_INVALID_PARAMETER), raw_uac);
		return LDB_ERR_OTHER;
	}

	if (old_atype != new_atype) {
		ret = samdb_msg_append_uint(ldb, ac->msg, ac->msg,
					    "sAMAccountType", new_atype,
					    LDB_FLAG_MOD_REPLACE);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	/* As per MS-SAMR 3.1.1.8.10 these flags have not to be set */
	if ((clear_uac & UF_LOCKOUT) && (old_lockoutTime != 0)) {
		/* "lockoutTime" reset as per MS-SAMR 3.1.1.8.10 */
		ldb_msg_remove_attr(ac->msg, "lockoutTime");
		ret = samdb_msg_append_uint64(ldb, ac->msg, ac->msg, "lockoutTime",
					      (NTTIME)0, LDB_FLAG_MOD_REPLACE);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	/*
	 * "isCriticalSystemObject" might be set/changed
	 *
	 * Even a change from UF_NORMAL_ACCOUNT (implicitly FALSE) to
	 * UF_WORKSTATION_TRUST_ACCOUNT (actually FALSE) triggers
	 * creating the attribute.
	 */
	if (old_is_critical != new_is_critical || old_atype != new_atype) {
		ret = ldb_msg_append_string(ac->msg, "isCriticalSystemObject",
					    new_is_critical ? "TRUE": "FALSE",
					    LDB_FLAG_MOD_REPLACE);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	if (!ldb_msg_find_element(ac->msg, "primaryGroupID") &&
	    (old_pgrid != new_pgrid)) {
		/* Older AD deployments don't know about the RODC group */
		if (new_pgrid == DOMAIN_RID_READONLY_DCS) {
			ret = samldb_prim_group_tester(ac, new_pgrid);
			if (ret != LDB_SUCCESS) {
				return ret;
			}
		}

		ret = samdb_msg_append_uint(ldb, ac->msg, ac->msg,
					    "primaryGroupID", new_pgrid,
					    LDB_FLAG_MOD_REPLACE);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	/* Propagate eventual "userAccountControl" attribute changes */
	if (old_uac != new_uac) {
		char *tempstr = talloc_asprintf(ac->msg, "%d",
						new_uac);
		if (tempstr == NULL) {
			return ldb_module_oom(ac->module);
		}

		ret = ldb_msg_add_empty(ac->msg,
					"userAccountControl",
					LDB_FLAG_MOD_REPLACE,
					&el);
		el->values = talloc(ac->msg, struct ldb_val);
		el->num_values = 1;
		el->values[0].data = (uint8_t *) tempstr;
		el->values[0].length = strlen(tempstr);
	} else {
		ldb_msg_remove_attr(ac->msg, "userAccountControl");
	}

	return LDB_SUCCESS;
}

static int samldb_check_pwd_last_set_acl(struct samldb_ctx *ac,
					 struct dom_sid *sid)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	int ret = 0;
	struct security_token *user_token = NULL;
	struct security_descriptor *domain_sd = NULL;
	struct ldb_dn *domain_dn = ldb_get_default_basedn(ldb_module_get_ctx(ac->module));
	const char *operation = "";
	const struct dsdb_class *objectclass = NULL;

	if (dsdb_module_am_system(ac->module)) {
		return LDB_SUCCESS;
	}

	switch (ac->req->operation) {
	case LDB_ADD:
		operation = "add";
		break;
	case LDB_MODIFY:
		operation = "modify";
		break;
	default:
		return ldb_module_operr(ac->module);
	}

	user_token = acl_user_token(ac->module);
	if (user_token == NULL) {
		return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
	}

	ret = samldb_get_domain_secdesc_and_oc(ac, &domain_sd, &objectclass);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	ret = acl_check_extended_right(ac,
				       ac->module,
				       ac->req,
				       objectclass,
				       domain_sd,
				       user_token,
				       GUID_DRS_UNEXPIRE_PASSWORD,
				       SEC_ADS_CONTROL_ACCESS,
				       sid);
	if (ret != LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS) {
		return ret;
	}

	ldb_debug_set(ldb, LDB_DEBUG_WARNING,
		      "Failed to %s %s: "
		      "Setting pwdLastSet to -1 requires the "
		      "Unexpire-Password right that was not given "
		      "on the Domain object",
		      operation,
		      ldb_dn_get_linearized(ac->msg->dn));
	dsdb_acl_debug(domain_sd, user_token,
		       domain_dn, true, 10);

	return ret;
}

/**
 * This function is called on LDB modify operations. It performs some additions/
 * replaces on the current LDB message when "pwdLastSet" changes.
 */
static int samldb_pwd_last_set_change(struct samldb_ctx *ac)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	NTTIME last_set = 0;
	struct ldb_message_element *el = NULL;
	struct ldb_message *tmp_msg = NULL;
	struct dom_sid *self_sid = NULL;
	int ret;
	struct ldb_result *res = NULL;
	const char * const attrs[] = {
		"objectSid",
		NULL
	};

	ret = dsdb_get_expected_new_values(ac,
					   ac->msg,
					   "pwdLastSet",
					   &el,
					   ac->req->operation);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	if (el == NULL || el->num_values == 0) {
		ldb_asprintf_errstring(ldb,
			"%08X: samldb: 'pwdLastSet' can't be deleted!",
			W_ERROR_V(WERR_DS_ILLEGAL_MOD_OPERATION));
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	/* Create a temporary message for fetching the "userAccountControl" */
	tmp_msg = ldb_msg_new(ac->msg);
	if (tmp_msg == NULL) {
		return ldb_module_oom(ac->module);
	}
	ret = ldb_msg_add(tmp_msg, el, 0);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	last_set = samdb_result_nttime(tmp_msg, "pwdLastSet", 0);
	talloc_free(tmp_msg);

	/*
	 * Setting -1 (0xFFFFFFFFFFFFFFFF) requires the Unexpire-Password right
	 */
	if (last_set != UINT64_MAX) {
		return LDB_SUCCESS;
	}

	/* Fetch the "objectSid" */
	ret = dsdb_module_search_dn(ac->module, ac, &res, ac->msg->dn, attrs,
				    DSDB_FLAG_NEXT_MODULE, ac->req);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	self_sid = samdb_result_dom_sid(res, res->msgs[0], "objectSid");
	if (self_sid == NULL) {
		return ldb_module_operr(ac->module);
	}

	ret = samldb_check_pwd_last_set_acl(ac, self_sid);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	return LDB_SUCCESS;
}

static int samldb_lockout_time(struct samldb_ctx *ac)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	NTTIME lockoutTime;
	struct ldb_message_element *el;
	struct ldb_message *tmp_msg;
	int ret;

	ret = dsdb_get_expected_new_values(ac,
					   ac->msg,
					   "lockoutTime",
					   &el,
					   ac->req->operation);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	if (el == NULL || el->num_values == 0) {
		ldb_asprintf_errstring(ldb,
			"%08X: samldb: 'lockoutTime' can't be deleted!",
			W_ERROR_V(WERR_DS_ILLEGAL_MOD_OPERATION));
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	/* Create a temporary message for fetching the "lockoutTime" */
	tmp_msg = ldb_msg_new(ac->msg);
	if (tmp_msg == NULL) {
		return ldb_module_oom(ac->module);
	}
	ret = ldb_msg_add(tmp_msg, el, 0);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	lockoutTime = ldb_msg_find_attr_as_int64(tmp_msg,
						 "lockoutTime",
						 0);
	talloc_free(tmp_msg);

	if (lockoutTime != 0) {
		return LDB_SUCCESS;
	}

	/* lockoutTime == 0 resets badPwdCount */
	ldb_msg_remove_attr(ac->msg, "badPwdCount");
	ret = samdb_msg_append_int(ldb, ac->msg, ac->msg,
				   "badPwdCount", 0,
				   LDB_FLAG_MOD_REPLACE);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	return LDB_SUCCESS;
}

static int samldb_group_type_change(struct samldb_ctx *ac)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	uint32_t group_type, old_group_type, account_type;
	struct ldb_message_element *el;
	struct ldb_message *tmp_msg;
	int ret;
	struct ldb_result *res;
	const char * const attrs[] = { "groupType", NULL };

	ret = dsdb_get_expected_new_values(ac,
					   ac->msg,
					   "groupType",
					   &el,
					   ac->req->operation);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	if (el == NULL) {
		/* we are not affected */
		return LDB_SUCCESS;
	}

	/* Create a temporary message for fetching the "groupType" */
	tmp_msg = ldb_msg_new(ac->msg);
	if (tmp_msg == NULL) {
		return ldb_module_oom(ac->module);
	}
	ret = ldb_msg_add(tmp_msg, el, 0);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	group_type = ldb_msg_find_attr_as_uint(tmp_msg, "groupType", 0);
	talloc_free(tmp_msg);

	ret = dsdb_module_search_dn(ac->module, ac, &res, ac->msg->dn, attrs,
				    DSDB_FLAG_NEXT_MODULE |
				    DSDB_SEARCH_SHOW_DELETED, ac->req);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	old_group_type = ldb_msg_find_attr_as_uint(res->msgs[0], "groupType", 0);
	if (old_group_type == 0) {
		return ldb_operr(ldb);
	}

	/* Group type switching isn't so easy as it seems: We can only
	 * change in this directions: global <-> universal <-> local
	 * On each step also the group type itself
	 * (security/distribution) is variable. */

	if (ldb_request_get_control(ac->req, LDB_CONTROL_PROVISION_OID) == NULL) {
		switch (group_type) {
		case GTYPE_SECURITY_GLOBAL_GROUP:
		case GTYPE_DISTRIBUTION_GLOBAL_GROUP:
			/* change to "universal" allowed */
			if ((old_group_type == GTYPE_SECURITY_DOMAIN_LOCAL_GROUP) ||
			(old_group_type == GTYPE_DISTRIBUTION_DOMAIN_LOCAL_GROUP)) {
				ldb_set_errstring(ldb,
					"samldb: Change from security/distribution local group forbidden!");
				return LDB_ERR_UNWILLING_TO_PERFORM;
			}
		break;

		case GTYPE_SECURITY_UNIVERSAL_GROUP:
		case GTYPE_DISTRIBUTION_UNIVERSAL_GROUP:
			/* each change allowed */
		break;
		case GTYPE_SECURITY_DOMAIN_LOCAL_GROUP:
		case GTYPE_DISTRIBUTION_DOMAIN_LOCAL_GROUP:
			/* change to "universal" allowed */
			if ((old_group_type == GTYPE_SECURITY_GLOBAL_GROUP) ||
			(old_group_type == GTYPE_DISTRIBUTION_GLOBAL_GROUP)) {
				ldb_set_errstring(ldb,
					"samldb: Change from security/distribution global group forbidden!");
				return LDB_ERR_UNWILLING_TO_PERFORM;
			}
		break;

		case GTYPE_SECURITY_BUILTIN_LOCAL_GROUP:
		default:
			/* we don't allow this "groupType" values */
			return LDB_ERR_UNWILLING_TO_PERFORM;
		break;
		}
	}

	account_type =  ds_gtype2atype(group_type);
	if (account_type == 0) {
		ldb_set_errstring(ldb, "samldb: Unrecognized account type!");
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}
	ret = samdb_msg_append_uint(ldb, ac->msg, ac->msg, "sAMAccountType",
				    account_type, LDB_FLAG_MOD_REPLACE);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	return LDB_SUCCESS;
}

static int samldb_member_check(struct samldb_ctx *ac)
{
	const char * const attrs[] = { "objectSid", NULL };
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	struct ldb_message_element *el;
	struct ldb_dn *member_dn;
	struct dom_sid *sid;
	struct ldb_result *res;
	struct dom_sid *group_sid;
	unsigned int i, j;
	int ret;

	/* Fetch information from the existing object */

	ret = dsdb_module_search(ac->module, ac, &res, ac->msg->dn, LDB_SCOPE_BASE, attrs,
				 DSDB_FLAG_NEXT_MODULE | DSDB_SEARCH_SHOW_DELETED, ac->req, NULL);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	if (res->count != 1) {
		return ldb_operr(ldb);
	}

	group_sid = samdb_result_dom_sid(res, res->msgs[0], "objectSid");
	if (group_sid == NULL) {
		return ldb_operr(ldb);
	}

	/* We've to walk over all modification entries and consider the "member"
	 * ones. */
	for (i = 0; i < ac->msg->num_elements; i++) {
		if (ldb_attr_cmp(ac->msg->elements[i].name, "member") != 0) {
			continue;
		}

		el = &ac->msg->elements[i];
		for (j = 0; j < el->num_values; j++) {
			struct ldb_result *group_res;
			const char *group_attrs[] = { "primaryGroupID" , NULL };
			uint32_t prim_group_rid;

			if (LDB_FLAG_MOD_TYPE(el->flags) == LDB_FLAG_MOD_DELETE) {
				/* Deletes will be handled in
				 * repl_meta_data, and deletes not
				 * matching a member will return
				 * LDB_ERR_UNWILLING_TO_PERFORM
				 * there */
				continue;
			}

			member_dn = ldb_dn_from_ldb_val(ac, ldb,
							&el->values[j]);
			if (!ldb_dn_validate(member_dn)) {
				return ldb_operr(ldb);
			}

			/* Denies to add "member"s to groups which are primary
			 * ones for them - in this case return
			 * ERR_ENTRY_ALREADY_EXISTS. */

			ret = dsdb_module_search_dn(ac->module, ac, &group_res,
						    member_dn, group_attrs,
						    DSDB_FLAG_NEXT_MODULE, ac->req);
			if (ret == LDB_ERR_NO_SUCH_OBJECT) {
				/* member DN doesn't exist yet */
				continue;
			}
			if (ret != LDB_SUCCESS) {
				return ret;
			}
			prim_group_rid = ldb_msg_find_attr_as_uint(group_res->msgs[0], "primaryGroupID", (uint32_t)-1);
			if (prim_group_rid == (uint32_t) -1) {
				/* the member hasn't to be a user account ->
				 * therefore no check needed in this case. */
				continue;
			}

			sid = dom_sid_add_rid(ac, samdb_domain_sid(ldb),
					      prim_group_rid);
			if (sid == NULL) {
				return ldb_operr(ldb);
			}

			if (dom_sid_equal(group_sid, sid)) {
				ldb_asprintf_errstring(ldb,
						       "samldb: member %s already set via primaryGroupID %u",
						       ldb_dn_get_linearized(member_dn), prim_group_rid);
				return LDB_ERR_ENTRY_ALREADY_EXISTS;
			}
		}
	}

	talloc_free(res);

	return LDB_SUCCESS;
}

/* SAM objects have special rules regarding the "description" attribute on
 * modify operations. */
static int samldb_description_check(struct samldb_ctx *ac, bool *modified)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	const char * const attrs[] = { "objectClass", "description", NULL };
	struct ldb_result *res;
	unsigned int i;
	int ret;

	/* Fetch information from the existing object */
	ret = dsdb_module_search(ac->module, ac, &res, ac->msg->dn, LDB_SCOPE_BASE, attrs,
				 DSDB_FLAG_NEXT_MODULE | DSDB_SEARCH_SHOW_DELETED, ac->req,
				 "(|(objectclass=user)(objectclass=group)(objectclass=samDomain)(objectclass=samServer))");
	if (ret != LDB_SUCCESS) {
		/* don't treat it specially ... let normal error codes
		   happen from other places */
		ldb_reset_err_string(ldb);
		return LDB_SUCCESS;
	}
	if (res->count == 0) {
		/* we didn't match the filter */
		talloc_free(res);
		return LDB_SUCCESS;
	}

	/* We've to walk over all modification entries and consider the
	 * "description" ones. */
	for (i = 0; i < ac->msg->num_elements; i++) {
		if (ldb_attr_cmp(ac->msg->elements[i].name, "description") == 0) {
			ac->msg->elements[i].flags |= LDB_FLAG_INTERNAL_FORCE_SINGLE_VALUE_CHECK;
			*modified = true;
		}
	}

	talloc_free(res);

	return LDB_SUCCESS;
}

#define SPN_ALIAS_NONE 0
#define SPN_ALIAS_LINK 1
#define SPN_ALIAS_TARGET 2

static int find_spn_aliases(struct ldb_context *ldb,
			    TALLOC_CTX *mem_ctx,
			    const char *service_class,
			    char ***aliases,
			    size_t *n_aliases,
			    int *direction)
{
	/*
	 * If you change the way this works, you should also look at changing
	 * LDB_lookup_spn_alias() in source4/dsdb/samdb/cracknames.c, which
	 * does some of the same work.
	 *
	 * In particular, note that sPNMappings are resolved on a first come,
	 * first served basis. For example, if we have
	 *
	 *  host=ldap,cifs
	 *  foo=ldap
	 *  cifs=host,alerter
	 *
	 * then 'ldap', 'cifs', and 'host' will resolve to 'host', and
	 * 'alerter' will resolve to 'cifs'.
	 *
	 * If this resolution method is made more complicated, then the
	 * cracknames function should also be changed.
	 */
	size_t i, j;
	int ret;
	bool ok;
	struct ldb_result *res = NULL;
	struct ldb_message_element *spnmappings = NULL;
	TALLOC_CTX *tmp_ctx = NULL;
	struct ldb_dn *service_dn = NULL;

	const char *attrs[] = {
		"sPNMappings",
		NULL
	};

	*direction = SPN_ALIAS_NONE;

	tmp_ctx = talloc_new(mem_ctx);
	if (tmp_ctx == NULL) {
		return ldb_oom(ldb);
	}

	service_dn = ldb_dn_new(
		tmp_ctx, ldb,
		"CN=Directory Service,CN=Windows NT,CN=Services");
	if (service_dn == NULL) {
		talloc_free(tmp_ctx);
		return ldb_oom(ldb);
	}

	ok = ldb_dn_add_base(service_dn, ldb_get_config_basedn(ldb));
	if (! ok) {
		talloc_free(tmp_ctx);
		return LDB_ERR_OPERATIONS_ERROR;
	}

	ret = ldb_search(ldb, tmp_ctx, &res, service_dn, LDB_SCOPE_BASE,
			 attrs, "(objectClass=nTDSService)");

	if (ret != LDB_SUCCESS || res->count != 1) {
		DBG_WARNING("sPNMappings not found.\n");
		talloc_free(tmp_ctx);
		return ret;
	}

	spnmappings = ldb_msg_find_element(res->msgs[0], "sPNMappings");
	if (spnmappings == NULL || spnmappings->num_values == 0) {
		DBG_WARNING("no sPNMappings attribute\n");
		talloc_free(tmp_ctx);
		return LDB_ERR_NO_SUCH_OBJECT;
	}
	*n_aliases = 0;

	for (i = 0; i < spnmappings->num_values; i++) {
		char *p = NULL;
		char *mapping = talloc_strndup(
			tmp_ctx,
			(char *)spnmappings->values[i].data,
			spnmappings->values[i].length);
		if (mapping == NULL) {
			talloc_free(tmp_ctx);
			return ldb_oom(ldb);
		}

		p = strchr(mapping, '=');
		if (p == NULL) {
			talloc_free(tmp_ctx);
			return LDB_ERR_ALIAS_PROBLEM;
		}
		p[0] = '\0';
		p++;

		if (strcasecmp(mapping, service_class) == 0) {
			/*
			 * We need to return the reverse aliases for this one.
			 *
			 * typically, this means the service_class is "host"
			 * and the mapping is "host=alerter,appmgmt,cisvc,..",
			 * so we get "alerter", "appmgmt", etc in the list of
			 * aliases.
			 */

			/* There is one more field than there are commas */
			size_t n = 1;

			for (j = 0; p[j] != '\0'; j++) {
				if (p[j] == ',') {
					n++;
					p[j] = '\0';
				}
			}
			*aliases = talloc_array(mem_ctx, char*, n);
			if (*aliases == NULL) {
				talloc_free(tmp_ctx);
				return ldb_oom(ldb);
			}
			*n_aliases = n;
			talloc_steal(mem_ctx, mapping);
			for (j = 0; j < n; j++) {
				(*aliases)[j] = p;
				p += strlen(p) + 1;
			}
			talloc_free(tmp_ctx);
			*direction = SPN_ALIAS_LINK;
			return LDB_SUCCESS;
		}
		/*
		 * We need to look along the list to see if service_class is
		 * there; if so, we return a list of one item (probably "host").
		 */
		do {
			char *str = p;
			p = strchr(p, ',');
			if (p != NULL) {
				p[0] = '\0';
				p++;
			}
			if (strcasecmp(str, service_class) == 0) {
				*aliases = talloc_array(mem_ctx, char*, 1);
				if (*aliases == NULL) {
					talloc_free(tmp_ctx);
					return ldb_oom(ldb);
				}
				*n_aliases = 1;
				(*aliases)[0] = mapping;
				talloc_steal(mem_ctx, mapping);
				talloc_free(tmp_ctx);
				*direction = SPN_ALIAS_TARGET;
				return LDB_SUCCESS;
			}
		} while (p != NULL);
	}
	DBG_INFO("no sPNMappings alias for '%s'\n", service_class);
	talloc_free(tmp_ctx);
	*aliases = NULL;
	*n_aliases = 0;
	return LDB_SUCCESS;
}


static int get_spn_dn(struct ldb_context *ldb,
		      TALLOC_CTX *tmp_ctx,
		      const char *candidate,
		      struct ldb_dn **dn)
{
	int ret;
	const char *empty_attrs[] = { NULL };
	struct ldb_message *msg = NULL;
	struct ldb_dn *base_dn = ldb_get_default_basedn(ldb);

	const char *enc_candidate = NULL;

	*dn = NULL;

	enc_candidate = ldb_binary_encode_string(tmp_ctx, candidate);
	if (enc_candidate == NULL) {
		return ldb_operr(ldb);
	}

	ret = dsdb_search_one(ldb,
			      tmp_ctx,
			      &msg,
			      base_dn,
			      LDB_SCOPE_SUBTREE,
			      empty_attrs,
			      0,
			      "(servicePrincipalName=%s)",
			      enc_candidate);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	*dn = msg->dn;
	return LDB_SUCCESS;
}


static int check_spn_write_rights(struct ldb_context *ldb,
				  TALLOC_CTX *mem_ctx,
				  const char *spn,
				  struct ldb_dn *dn)
{
	int ret;
	struct ldb_message *msg = NULL;
	struct ldb_message_element *del_el = NULL;
	struct ldb_message_element *add_el = NULL;
	struct ldb_val val = {
		.data = discard_const_p(uint8_t, spn),
		.length = strlen(spn)
	};

	msg = ldb_msg_new(mem_ctx);
	if (msg == NULL) {
		return ldb_oom(ldb);
	}
	msg->dn = dn;

	ret = ldb_msg_add_empty(msg,
				"servicePrincipalName",
				LDB_FLAG_MOD_DELETE,
				&del_el);
	if (ret != LDB_SUCCESS) {
		talloc_free(msg);
		return ret;
	}

	del_el->values = talloc_array(msg->elements, struct ldb_val, 1);
	if (del_el->values == NULL) {
		talloc_free(msg);
		return ret;
	}

	del_el->values[0] = val;
	del_el->num_values = 1;

	ret = ldb_msg_add_empty(msg,
				"servicePrincipalName",
				LDB_FLAG_MOD_ADD,
				&add_el);
	if (ret != LDB_SUCCESS) {
		talloc_free(msg);
		return ret;
	}

	add_el->values = talloc_array(msg->elements, struct ldb_val, 1);
	if (add_el->values == NULL) {
		talloc_free(msg);
		return ret;
	}

	add_el->values[0] = val;
	add_el->num_values = 1;

	ret = ldb_modify(ldb, msg);
	if (ret == LDB_ERR_NO_SUCH_ATTRIBUTE) {
		DBG_ERR("hmm I think we're OK, but not sure\n");
	} else if (ret != LDB_SUCCESS) {
		DBG_ERR("SPN write rights check failed with %d\n", ret);
		talloc_free(msg);
		return ret;
	}
	talloc_free(msg);
	return LDB_SUCCESS;
}


static int check_spn_alias_collision(struct ldb_context *ldb,
				     TALLOC_CTX *mem_ctx,
				     const char *spn,
				     struct ldb_dn *target_dn)
{
	int ret;
	char *service_class = NULL;
	char *spn_tail = NULL;
	char *p = NULL;
	char **aliases = NULL;
	size_t n_aliases = 0;
	size_t i, len;
	TALLOC_CTX *tmp_ctx = NULL;
	const char *target_dnstr = ldb_dn_get_linearized(target_dn);
	int link_direction;

	tmp_ctx = talloc_new(mem_ctx);
	if (tmp_ctx == NULL) {
		return ldb_oom(ldb);
	}

	/*
	 * "dns/example.com/xxx"  gives
	 *    service_class = "dns"
	 *    spn_tail      = "example.com/xxx"
	 */
	p = strchr(spn, '/');
	if (p == NULL) {
		/* bad SPN */
		talloc_free(tmp_ctx);
		return ldb_error(ldb,
				 LDB_ERR_OPERATIONS_ERROR,
				 "malformed servicePrincipalName");
	}
	len = p - spn;

	service_class = talloc_strndup(tmp_ctx, spn, len);
	if (service_class == NULL) {
		talloc_free(tmp_ctx);
		return ldb_oom(ldb);
	}
	spn_tail = p + 1;

	ret = find_spn_aliases(ldb,
			       tmp_ctx,
			       service_class,
			       &aliases,
			       &n_aliases,
			       &link_direction);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	/*
	 * we have the list of aliases, and now we need to combined them with
	 * spn_tail and see if we can find the SPN.
	 */
	for (i = 0; i < n_aliases; i++) {
		struct ldb_dn *colliding_dn = NULL;
		const char *colliding_dnstr = NULL;

		char *candidate = talloc_asprintf(tmp_ctx,
						  "%s/%s",
						  aliases[i],
						  spn_tail);
		if (candidate == NULL) {
			talloc_free(tmp_ctx);
			return ldb_oom(ldb);
		}

		ret = get_spn_dn(ldb, tmp_ctx, candidate, &colliding_dn);
		if (ret == LDB_ERR_NO_SUCH_OBJECT) {
			DBG_DEBUG("SPN alias '%s' not found (good)\n",
				  candidate);
			talloc_free(candidate);
			continue;
		}
		if (ret != LDB_SUCCESS) {
			DBG_ERR("SPN '%s' search error %d\n", candidate, ret);
			talloc_free(tmp_ctx);
			return ret;
		}

		target_dnstr = ldb_dn_get_linearized(target_dn);
		/*
		 * We have found an existing SPN that matches the alias. That
		 * is OK only if it is on the object we are trying to add to,
		 * or if the SPN on the other side is a more generic alias for
		 * this one and we also have rights to modify it.
		 *
		 * That is, we can put "host/X" and "cifs/X" on the same
		 * object, but not on different objects, unless we put the
		 * host/X on first, and could also change that object when we
		 * add cifs/X. It is forbidden to add the objects in the other
		 * order.
		 *
		 * The rationale for this is that adding "cifs/X" effectively
		 * changes "host/X" by diverting traffic. If "host/X" can be
		 * added after "cifs/X", a sneaky person could get "cifs/X" in
		 * first, making "host/X" have less effect than intended.
		 *
		 * Note: we also can't have "host/X" and "Host/X" on the same
		 * object, but that is not relevant here.
		 */

		ret = ldb_dn_compare(colliding_dn, target_dn);
		if (ret != 0) {
			colliding_dnstr = ldb_dn_get_linearized(colliding_dn);
			DBG_ERR("trying to add SPN '%s' on '%s' when '%s' is "
				"on '%s'\n",
				spn,
				target_dnstr,
				candidate,
				colliding_dnstr);

			if (link_direction == SPN_ALIAS_LINK) {
				/* we don't allow host/X if there is a
				 * cifs/X */
				talloc_free(tmp_ctx);
				return LDB_ERR_CONSTRAINT_VIOLATION;
			}
			ret = check_spn_write_rights(ldb,
						     tmp_ctx,
						     candidate,
						     colliding_dn);
			if (ret != LDB_SUCCESS) {
				DBG_ERR("SPN '%s' is on '%s' so '%s' can't be "
					"added to '%s'\n",
					candidate,
					colliding_dnstr,
					spn,
					target_dnstr);
				talloc_free(tmp_ctx);
				ldb_asprintf_errstring(ldb,
						       "samldb: spn[%s] would cause a conflict",
						       spn);
				return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
			}
		} else {
			DBG_INFO("SPNs '%s' and '%s' alias both on '%s'\n",
				 candidate, spn, target_dnstr);
		}
		talloc_free(candidate);
	}

	talloc_free(tmp_ctx);
	return LDB_SUCCESS;
}

static int check_spn_direct_collision(struct ldb_context *ldb,
				      TALLOC_CTX *mem_ctx,
				      const char *spn,
				      struct ldb_dn *target_dn)
{
	int ret;
	TALLOC_CTX *tmp_ctx = NULL;
	struct ldb_dn *colliding_dn = NULL;
	const char *target_dnstr = NULL;
	const char *colliding_dnstr = NULL;

	tmp_ctx = talloc_new(mem_ctx);
	if (tmp_ctx == NULL) {
		return ldb_oom(ldb);
	}

	ret = get_spn_dn(ldb, tmp_ctx, spn, &colliding_dn);
	if (ret == LDB_ERR_NO_SUCH_OBJECT) {
		DBG_DEBUG("SPN '%s' not found (good)\n", spn);
		talloc_free(tmp_ctx);
		return LDB_SUCCESS;
	}
	if (ret != LDB_SUCCESS) {
		DBG_ERR("SPN '%s' search error %d\n", spn, ret);
		talloc_free(tmp_ctx);
		if (ret == LDB_ERR_COMPARE_TRUE) {
			/*
			 * COMPARE_TRUE has special meaning here and we don't
			 * want to return it by mistake.
			 */
			ret = LDB_ERR_OPERATIONS_ERROR;
		}
		return ret;
	}
	/*
	 * We have found this exact SPN. This is mostly harmless (depend on
	 * ADD vs REPLACE) when the spn is being put on the object that
	 * already has, so we let it through to succeed or fail as some other
	 * module sees fit.
	 */
	target_dnstr = ldb_dn_get_linearized(target_dn);
	ret = ldb_dn_compare(colliding_dn, target_dn);
	if (ret != 0) {
		colliding_dnstr = ldb_dn_get_linearized(colliding_dn);
		DBG_ERR("SPN '%s' is on '%s' so it can't be "
			"added to '%s'\n",
			spn,
			colliding_dnstr,
			target_dnstr);
		ldb_asprintf_errstring(ldb,
				       "samldb: spn[%s] would cause a conflict",
				       spn);
		talloc_free(tmp_ctx);
		return LDB_ERR_CONSTRAINT_VIOLATION;
	}

	DBG_INFO("SPN '%s' is already on '%s'\n",
		 spn, target_dnstr);
	talloc_free(tmp_ctx);
	return LDB_ERR_COMPARE_TRUE;
}


static int count_spn_components(struct ldb_val val)
{
	/*
	 * a 3 part servicePrincipalName has two slashes, like
	 * ldap/example.com/DomainDNSZones.example.com.
	 *
	 * In krb5_parse_name_flags() we don't count "\/" as a slash (i.e.
	 * escaped by a backslash), but this is not the behaviour of Windows
	 * on setting a servicePrincipalName -- slashes are counted regardless
	 * of backslashes.
	 *
	 * Accordingly, here we ignore backslashes. This will reject
	 * multi-slash SPNs that krb5_parse_name_flags() would accept, and
	 * allow ones in the form "a\/b" that it won't parse.
	 */
	size_t i;
	int slashes = 0;
	for (i = 0; i < val.length; i++) {
		char c = val.data[i];
		if (c == '/') {
			slashes++;
			if (slashes == 3) {
				/* at this point we don't care */
				return 4;
			}
		}
	}
	return slashes + 1;
}


/* Check that "servicePrincipalName" changes do not introduce a collision
 * globally. */
static int samldb_spn_uniqueness_check(struct samldb_ctx *ac,
				       struct ldb_message_element *spn_el)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	int ret;
	const char *spn = NULL;
	size_t i;
	TALLOC_CTX *tmp_ctx = talloc_new(ac->msg);
	if (tmp_ctx == NULL) {
		return ldb_oom(ldb);
	}

	for (i = 0; i < spn_el->num_values; i++) {
		int n_components;
		spn = (char *)spn_el->values[i].data;

		n_components = count_spn_components(spn_el->values[i]);
		if (n_components > 3 || n_components < 2) {
			ldb_asprintf_errstring(ldb,
					       "samldb: spn[%s] invalid with %u components",
					       spn, n_components);
			talloc_free(tmp_ctx);
			return LDB_ERR_CONSTRAINT_VIOLATION;
		}

		ret = check_spn_direct_collision(ldb,
						 tmp_ctx,
						 spn,
						 ac->msg->dn);
		if (ret == LDB_ERR_COMPARE_TRUE) {
			DBG_INFO("SPN %s re-added to the same object\n", spn);
			continue;
		}
		if (ret != LDB_SUCCESS) {
			DBG_ERR("SPN %s failed direct uniqueness check\n", spn);
			talloc_free(tmp_ctx);
			return ret;
		}

		ret = check_spn_alias_collision(ldb,
						tmp_ctx,
						spn,
						ac->msg->dn);

		if (ret == LDB_ERR_NO_SUCH_OBJECT) {
			/* we have no sPNMappings, hence no aliases */
			break;
		}
		if (ret != LDB_SUCCESS) {
			DBG_ERR("SPN %s failed alias uniqueness check\n", spn);
			talloc_free(tmp_ctx);
			return ret;
		}
		DBG_INFO("SPN %s seems to be unique\n", spn);
	}

	talloc_free(tmp_ctx);
	return LDB_SUCCESS;
}



/* This trigger adapts the "servicePrincipalName" attributes if the
 * "dNSHostName" and/or "sAMAccountName" attribute change(s) */
static int samldb_service_principal_names_change(struct samldb_ctx *ac)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	struct ldb_message_element *el = NULL, *el2 = NULL;
	struct ldb_message *msg;
	const char * const attrs[] = { "servicePrincipalName", NULL };
	struct ldb_result *res;
	const char *dns_hostname = NULL, *old_dns_hostname = NULL,
		   *sam_accountname = NULL, *old_sam_accountname = NULL;
	unsigned int i, j;
	int ret;

	ret = dsdb_get_expected_new_values(ac,
					   ac->msg,
					   "dNSHostName",
					   &el,
					   ac->req->operation);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	ret = dsdb_get_expected_new_values(ac,
					   ac->msg,
					   "sAMAccountName",
					   &el2,
					   ac->req->operation);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	if ((el == NULL) && (el2 == NULL)) {
		/* we are not affected */
		return LDB_SUCCESS;
	}

	/* Create a temporary message for fetching the "dNSHostName" */
	if (el != NULL) {
		const char *dns_attrs[] = { "dNSHostName", NULL };
		msg = ldb_msg_new(ac->msg);
		if (msg == NULL) {
			return ldb_module_oom(ac->module);
		}
		ret = ldb_msg_add(msg, el, 0);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
		dns_hostname = talloc_strdup(ac,
					     ldb_msg_find_attr_as_string(msg, "dNSHostName", NULL));
		if (dns_hostname == NULL) {
			return ldb_module_oom(ac->module);
		}

		talloc_free(msg);

		ret = dsdb_module_search_dn(ac->module, ac, &res, ac->msg->dn,
					    dns_attrs, DSDB_FLAG_NEXT_MODULE, ac->req);
		if (ret == LDB_SUCCESS) {
			old_dns_hostname = ldb_msg_find_attr_as_string(res->msgs[0], "dNSHostName", NULL);
		}
	}

	/* Create a temporary message for fetching the "sAMAccountName" */
	if (el2 != NULL) {
		char *tempstr, *tempstr2 = NULL;
		const char *acct_attrs[] = { "sAMAccountName", NULL };

		msg = ldb_msg_new(ac->msg);
		if (msg == NULL) {
			return ldb_module_oom(ac->module);
		}
		ret = ldb_msg_add(msg, el2, 0);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
		tempstr = talloc_strdup(ac,
					ldb_msg_find_attr_as_string(msg, "sAMAccountName", NULL));
		talloc_free(msg);

		ret = dsdb_module_search_dn(ac->module, ac, &res, ac->msg->dn, acct_attrs,
					    DSDB_FLAG_NEXT_MODULE, ac->req);
		if (ret == LDB_SUCCESS) {
			tempstr2 = talloc_strdup(ac,
						 ldb_msg_find_attr_as_string(res->msgs[0],
									     "sAMAccountName", NULL));
		}


		/* The "sAMAccountName" needs some additional trimming: we need
		 * to remove the trailing "$"s if they exist. */
		if ((tempstr != NULL) && (tempstr[0] != '\0') &&
		    (tempstr[strlen(tempstr) - 1] == '$')) {
			tempstr[strlen(tempstr) - 1] = '\0';
		}
		if ((tempstr2 != NULL) && (tempstr2[0] != '\0') &&
		    (tempstr2[strlen(tempstr2) - 1] == '$')) {
			tempstr2[strlen(tempstr2) - 1] = '\0';
		}
		sam_accountname = tempstr;
		old_sam_accountname = tempstr2;
	}

	if (old_dns_hostname == NULL) {
		/* we cannot change when the old name is unknown */
		dns_hostname = NULL;
	}
	if ((old_dns_hostname != NULL) && (dns_hostname != NULL) &&
	    (strcasecmp_m(old_dns_hostname, dns_hostname) == 0)) {
		/* The "dNSHostName" didn't change */
		dns_hostname = NULL;
	}

	if (old_sam_accountname == NULL) {
		/* we cannot change when the old name is unknown */
		sam_accountname = NULL;
	}
	if ((old_sam_accountname != NULL) && (sam_accountname != NULL) &&
	    (strcasecmp_m(old_sam_accountname, sam_accountname) == 0)) {
		/* The "sAMAccountName" didn't change */
		sam_accountname = NULL;
	}

	if ((dns_hostname == NULL) && (sam_accountname == NULL)) {
		/* Well, there are information missing (old name(s)) or the
		 * names didn't change. We've nothing to do and can exit here */
		return LDB_SUCCESS;
	}

	/*
	 * Potential "servicePrincipalName" changes in the same request have
	 * to be handled before the update (Windows behaviour).
	 *
	 * We extract the SPN changes into a new message and run it through
	 * the stack from this module, so that it subjects them to the SPN
	 * checks we have here.
	 */
	el = ldb_msg_find_element(ac->msg, "servicePrincipalName");
	if (el != NULL) {
		msg = ldb_msg_new(ac->msg);
		if (msg == NULL) {
			return ldb_module_oom(ac->module);
		}
		msg->dn = ac->msg->dn;

		do {
			ret = ldb_msg_add(msg, el, el->flags);
			if (ret != LDB_SUCCESS) {
				return ret;
			}

			ldb_msg_remove_element(ac->msg, el);

			el = ldb_msg_find_element(ac->msg,
						  "servicePrincipalName");
		} while (el != NULL);

		ret = dsdb_module_modify(ac->module, msg,
					 DSDB_FLAG_OWN_MODULE, ac->req);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
		talloc_free(msg);
	}

	/* Fetch the "servicePrincipalName"s if any */
	ret = dsdb_module_search(ac->module, ac, &res, ac->msg->dn, LDB_SCOPE_BASE, attrs,
				 DSDB_FLAG_NEXT_MODULE, ac->req, NULL);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	if ((res->count != 1) || (res->msgs[0]->num_elements > 1)) {
		return ldb_operr(ldb);
	}

	if (res->msgs[0]->num_elements == 1) {
		/*
		 * Yes, we do have "servicePrincipalName"s. First we update them
		 * locally, that means we do always substitute the current
		 * "dNSHostName" with the new one and/or "sAMAccountName"
		 * without "$" with the new one and then we append the
		 * modified "servicePrincipalName"s as a message element
		 * replace to the modification request (Windows behaviour). We
		 * need also to make sure that the values remain case-
		 * insensitively unique.
		 */

		ret = ldb_msg_add_empty(ac->msg, "servicePrincipalName",
					LDB_FLAG_MOD_REPLACE, &el);
		if (ret != LDB_SUCCESS) {
			return ret;
		}

		for (i = 0; i < res->msgs[0]->elements[0].num_values; i++) {
			char *old_str, *new_str;
			char *pos = NULL;
			const char *tok;
			struct ldb_val *vals;
			bool found = false;

			old_str = (char *)
				res->msgs[0]->elements[0].values[i].data;

			new_str = talloc_strdup(ac->msg,
						strtok_r(old_str, "/", &pos));
			if (new_str == NULL) {
				return ldb_module_oom(ac->module);
			}

			while ((tok = strtok_r(NULL, "/", &pos)) != NULL) {
				if ((dns_hostname != NULL) &&
				    (strcasecmp_m(tok, old_dns_hostname) == 0)) {
					tok = dns_hostname;
				}
				if ((sam_accountname != NULL) &&
				    (strcasecmp_m(tok, old_sam_accountname) == 0)) {
					tok = sam_accountname;
				}

				new_str = talloc_asprintf(ac->msg, "%s/%s",
							  new_str, tok);
				if (new_str == NULL) {
					return ldb_module_oom(ac->module);
				}
			}

			/* Uniqueness check */
			for (j = 0; (!found) && (j < el->num_values); j++) {
				if (strcasecmp_m((char *)el->values[j].data,
					       new_str) == 0) {
					found = true;
				}
			}
			if (found) {
				continue;
			}

			/*
			 * append the new "servicePrincipalName" -
			 * code derived from ldb_msg_add_value().
			 *
			 * Open coded to make it clear that we must
			 * append to the MOD_REPLACE el created above.
			 */
			vals = talloc_realloc(ac->msg, el->values,
					      struct ldb_val,
					      el->num_values + 1);
			if (vals == NULL) {
				return ldb_module_oom(ac->module);
			}
			el->values = vals;
			el->values[el->num_values] = data_blob_string_const(new_str);
			++(el->num_values);
		}
	}

	talloc_free(res);

	return LDB_SUCCESS;
}

/* This checks the "fSMORoleOwner" attributes */
static int samldb_fsmo_role_owner_check(struct samldb_ctx *ac)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	const char * const no_attrs[] = { NULL };
	struct ldb_message_element *el;
	struct ldb_message *tmp_msg;
	struct ldb_dn *res_dn;
	struct ldb_result *res;
	int ret;
	ret = dsdb_get_expected_new_values(ac,
					   ac->msg,
					   "fSMORoleOwner",
					   &el,
					   ac->req->operation);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	if (el == NULL) {
		/* we are not affected */
		return LDB_SUCCESS;
	}
	if (el->num_values != 1) {
		goto choose_error_code;
	}

	/* Create a temporary message for fetching the "fSMORoleOwner" */
	tmp_msg = ldb_msg_new(ac->msg);
	if (tmp_msg == NULL) {
		return ldb_module_oom(ac->module);
	}
	ret = ldb_msg_add(tmp_msg, el, 0);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	res_dn = ldb_msg_find_attr_as_dn(ldb, ac, tmp_msg, "fSMORoleOwner");
	talloc_free(tmp_msg);

	if (res_dn == NULL) {
		ldb_set_errstring(ldb,
				  "samldb: 'fSMORoleOwner' attributes have to reference 'nTDSDSA' entries!");
		goto choose_error_code;
	}

	/* Fetched DN has to reference a "nTDSDSA" entry */
	ret = dsdb_module_search(ac->module, ac, &res, res_dn, LDB_SCOPE_BASE,
				 no_attrs,
				 DSDB_FLAG_NEXT_MODULE | DSDB_SEARCH_SHOW_DELETED,
				 ac->req, "(objectClass=nTDSDSA)");
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	if (res->count != 1) {
		ldb_set_errstring(ldb,
				  "samldb: 'fSMORoleOwner' attributes have to reference 'nTDSDSA' entries!");
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	talloc_free(res);

	return LDB_SUCCESS;

choose_error_code:
	/* this is just how it is */
	if (ac->req->operation == LDB_ADD) {
		return LDB_ERR_CONSTRAINT_VIOLATION;
	} else {
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}
}

/*
 * Return zero if the number of zero bits in the address (looking from low to
 * high) is equal to or greater than the length minus the mask. Otherwise it
 * returns -1.
 */
static int check_cidr_zero_bits(uint8_t *address, unsigned int len,
				unsigned int mask)
{
	/* <address> is an integer in big-endian form, <len> bits long. All
	   bits between <mask> and <len> must be zero. */
	int i;
	unsigned int byte_len;
	unsigned int byte_mask;
	unsigned int bit_mask;
	if (len == 32) {
		DBG_INFO("Looking at address %02x%02x%02x%02x, mask %u\n",
			 address[0], address[1], address[2], address[3],
			  mask);
	} else if (len == 128){
		DBG_INFO("Looking at address "
			 "%02x%02x-%02x%02x-%02x%02x-%02x%02x-"
			 "%02x%02x-%02x%02x-%02x%02x-%02x%02x, mask %u\n",
			 address[0], address[1], address[2], address[3],
			 address[4], address[5], address[6], address[7],
			 address[8], address[9], address[10], address[11],
			 address[12], address[13], address[14], address[15],
			 mask);
	}

	if (mask > len){
		DBG_INFO("mask %u is too big (> %u)\n", mask, len);
		return -1;
	}
	if (mask == len){
		/* single address subnet.
		 * In IPv4 all 255s is invalid by the bitmask != address rule
		 * in MS-ADTS. IPv6 does not suffer.
		 */
		if (len == 32){
			if (address[0] == 255 &&
			    address[1] == 255 &&
			    address[2] == 255 &&
			    address[3] == 255){
				return -1;
			}
		}
		return 0;
	}

	byte_len = len / 8;
	byte_mask = mask / 8;

	for (i = byte_len - 1; i > byte_mask; i--){
		DBG_DEBUG("checking byte %d %02x\n", i, address[i]);
		if (address[i] != 0){
			return -1;
		}
	}
	bit_mask = (1 << (8 - (mask & 7))) - 1;
	DBG_DEBUG("checking bitmask %02x & %02x overlap %02x\n", bit_mask, address[byte_mask],
		  bit_mask & address[byte_mask]);
	if (address[byte_mask] & bit_mask){
		return -1;
	}

	/* According to MS-ADTS, the mask can't exactly equal the bitmask for
	 * IPv4 (but this is fine for v6). That is 255.255.80.0/17 is bad,
	 * because the bitmask implied by "/17" is 255.255.80.0.
	 *
	 * The bit_mask used in the previous check is the complement of what
	 * we want here.
	 */
	if (len == 32 && address[byte_mask] == (uint8_t)~bit_mask){
		bool ok = false;
		for (i = 0; i < byte_mask; i++){
			if (address[i] != 255){
				ok = true;
				break;
			}
		}
		if (ok == false){
			return -1;
		}
	}
	return 0;
}



static int check_address_roundtrip(const char *address, int family,
				   const uint8_t *address_bytes,
				   char *buffer, int buffer_len)
{
	/*
	 * Check that the address is in the canonical RFC5952 format for IPv6,
	 * and lacks extra leading zeros for each dotted decimal for IPv4.
	 * Handily this is what inet_ntop() gives you.
	 */
	const char *address_redux = inet_ntop(family, address_bytes,
					      buffer, buffer_len);
	if (address_redux == NULL){
		DBG_INFO("Address round trip %s failed unexpectedly"
			 " with errno %d\n", address, errno);
		return -1;
	}
	if (strcasecmp(address, address_redux) != 0){
		DBG_INFO("Address %s round trips to %s; fail!\n",
			 address, address_redux);
		/* If the address family is IPv6, and the address is in a
		   certain range

		 */
		if (strchr(address_redux, '.') != NULL){
			DEBUG(0, ("The IPv6 address '%s' has the misfortune of "
				  "lying in a range that was once used for "
				  "IPv4 embedding (that is, it might also be "
				  "represented as '%s').\n", address,
				  address_redux));
		}
		return -1;
	}
	return 0;
}



/*
 * MS-ADTS v20150630 6.1.1.2.2.2.1 Subnet Object, refers to RFC1166 and
 * RFC2373. It specifies something seemingly indistinguishable from an RFC4632
 * CIDR address range without saying so explicitly. Here we follow the CIDR
 * spec.
 *
 * Return 0 on success, -1 on error.
 */
static int verify_cidr(const char *cidr)
{
	char *address = NULL, *slash = NULL;
	bool has_colon, has_dot;
	int res, ret;
	unsigned long mask;
	uint8_t *address_bytes = NULL;
	char *address_redux = NULL;
	unsigned int address_len;
	TALLOC_CTX *frame = NULL;
	int error = 0;

	DBG_DEBUG("CIDR is %s\n", cidr);
	frame = talloc_stackframe();
	address = talloc_strdup(frame, cidr);
	if (address == NULL){
		goto error;
	}

	/* there must be a '/' */
	slash = strchr(address, '/');
	if (slash == NULL){
		goto error;
	}
	/* terminate the address for strchr, inet_pton */
	*slash = '\0';

	mask = smb_strtoul(slash + 1, NULL, 10, &error, SMB_STR_FULL_STR_CONV);
	if (mask == 0){
		DBG_INFO("Windows does not like the zero mask, "
			 "so nor do we: %s\n", cidr);
		goto error;
	}

	if (error != 0){
		DBG_INFO("CIDR mask is not a proper integer: %s\n", cidr);
		goto error;
	}

	address_bytes = talloc_size(frame, sizeof(struct in6_addr));
	if (address_bytes == NULL){
		goto error;
	}

	address_redux = talloc_size(frame, INET6_ADDRSTRLEN);
	if (address_redux == NULL){
		goto error;
	}

	DBG_INFO("found address %s, mask %lu\n", address, mask);
	has_colon = (strchr(address, ':') == NULL) ? false : true;
	has_dot = (strchr(address, '.') == NULL) ? false : true;
	if (has_dot && has_colon){
		/* This seems to be an IPv4 address embedded in IPv6, which is
		   icky. We don't support it. */
		DBG_INFO("Refusing to consider cidr '%s' with dots and colons\n",
			  cidr);
		goto error;
	} else if (has_colon){	/* looks like IPv6 */
		res = inet_pton(AF_INET6, address, address_bytes);
		if (res != 1) {
			DBG_INFO("Address in %s fails to parse as IPv6\n", cidr);
			goto error;
		}
		address_len = 128;
		if (check_address_roundtrip(address, AF_INET6, address_bytes,
					    address_redux, INET6_ADDRSTRLEN)){
			goto error;
		}
	} else if (has_dot) {
		/* looks like IPv4 */
		if (strcmp(address, "0.0.0.0") == 0){
			DBG_INFO("Windows does not like the zero IPv4 address, "
				 "so nor do we.\n");
			goto error;
		}
		res = inet_pton(AF_INET, address, address_bytes);
		if (res != 1) {
			DBG_INFO("Address in %s fails to parse as IPv4\n", cidr);
			goto error;
		}
		address_len = 32;

		if (check_address_roundtrip(address, AF_INET, address_bytes,
					    address_redux, INET_ADDRSTRLEN)){
			goto error;
		}
	} else {
		/* This doesn't look like an IP address at all. */
		goto error;
	}

	ret = check_cidr_zero_bits(address_bytes, address_len, mask);
	talloc_free(frame);
	return ret;
  error:
	talloc_free(frame);
	return -1;
}


static int samldb_verify_subnet(struct samldb_ctx *ac, struct ldb_dn *dn)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	const char *cidr = NULL;
	const struct ldb_val *rdn_value = NULL;

	rdn_value = ldb_dn_get_rdn_val(dn);
	if (rdn_value == NULL) {
		ldb_set_errstring(ldb, "samldb: ldb_dn_get_rdn_val "
				  "failed");
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	cidr = ldb_dn_escape_value(ac, *rdn_value);
	DBG_INFO("looking at cidr '%s'\n", cidr);
	if (cidr == NULL) {
		ldb_set_errstring(ldb,
				  "samldb: adding an empty subnet cidr seems wrong");
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	if (verify_cidr(cidr)){
		ldb_set_errstring(ldb,
				  "samldb: subnet value is invalid");
		return LDB_ERR_INVALID_DN_SYNTAX;
	}

	return LDB_SUCCESS;
}

static char *refer_if_rodc(struct ldb_context *ldb, struct ldb_request *req,
			   struct ldb_dn *dn)
{
	bool rodc = false;
	struct loadparm_context *lp_ctx;
	char *referral;
	int ret;
	WERROR err;

	if (ldb_request_get_control(req, DSDB_CONTROL_REPLICATED_UPDATE_OID) ||
	    ldb_request_get_control(req, DSDB_CONTROL_DBCHECK_MODIFY_RO_REPLICA)) {
		return NULL;
	}

	ret = samdb_rodc(ldb, &rodc);
	if (ret != LDB_SUCCESS) {
		DEBUG(4, (__location__ ": unable to tell if we are an RODC\n"));
		return NULL;
	}

	if (rodc) {
		const char *domain = NULL;
		struct ldb_dn *fsmo_role_dn;
		struct ldb_dn *role_owner_dn;
		ldb_set_errstring(ldb, "RODC modify is forbidden!");
		lp_ctx = talloc_get_type(ldb_get_opaque(ldb, "loadparm"),
					 struct loadparm_context);

		err = dsdb_get_fsmo_role_info(req, ldb, DREPL_PDC_MASTER,
					      &fsmo_role_dn, &role_owner_dn);
		if (W_ERROR_IS_OK(err)) {
			struct ldb_dn *server_dn = ldb_dn_copy(req, role_owner_dn);
			if (server_dn != NULL) {
				ldb_dn_remove_child_components(server_dn, 1);

				domain = samdb_dn_to_dnshostname(ldb, req,
								 server_dn);
			}
		}
		if (domain == NULL) {
			domain = lpcfg_dnsdomain(lp_ctx);
		}
		referral = talloc_asprintf(req,
					   "ldap://%s/%s",
					   domain,
					   ldb_dn_get_linearized(dn));
		return referral;
	}

	return NULL;
}

/*
 * Restrict all access to sensitive attributes.
 *
 * We don't want to even inspect the values, so we can use the same
 * routine for ADD and MODIFY.
 *
 */

static int samldb_check_sensitive_attributes(struct samldb_ctx *ac)
{
	struct ldb_message_element *el = NULL;
	struct security_token *user_token = NULL;
	int ret;

	if (dsdb_module_am_system(ac->module)) {
		return LDB_SUCCESS;
	}

	user_token = acl_user_token(ac->module);
	if (user_token == NULL) {
		return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
	}

	el = ldb_msg_find_element(ac->msg, "sidHistory");
	if (el) {
               /*
                * sidHistory is restricted to the (not implemented
                * yet in Samba) DsAddSidHistory call (direct LDB access is
                * as SYSTEM so will bypass this).
		*
		* If you want to modify this, say to merge domains,
		* directly modify the sam.ldb as root.
                */
		ldb_asprintf_errstring(ldb_module_get_ctx(ac->module),
				       "sidHistory "
				       "(entry %s) cannot be created "
				       "or changed over LDAP!",
				       ldb_dn_get_linearized(ac->msg->dn));
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	el = ldb_msg_find_element(ac->msg, "msDS-SecondaryKrbTgtNumber");
	if (el) {
		struct security_descriptor *domain_sd;
		const struct dsdb_class *objectclass = NULL;
		/*
		 * msDS-SecondaryKrbTgtNumber allows the creator to
		 * become an RODC, this is trusted as an RODC
		 * account
		 */
		ret = samldb_get_domain_secdesc_and_oc(ac, &domain_sd, &objectclass);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
		ret = acl_check_extended_right(ac,
					       ac->module,
					       ac->req,
					       objectclass,
					       domain_sd,
					       user_token,
					       GUID_DRS_DS_INSTALL_REPLICA,
					       SEC_ADS_CONTROL_ACCESS,
					       NULL);
		if (ret != LDB_SUCCESS) {
			ldb_asprintf_errstring(ldb_module_get_ctx(ac->module),
					       "msDS-SecondaryKrbTgtNumber "
					       "(entry %s) cannot be created "
					       "or changed without "
					       "DS-Install-Replica extended right!",
					       ldb_dn_get_linearized(ac->msg->dn));
			return ret;
		}
	}

	el = ldb_msg_find_element(ac->msg, "msDS-AllowedToDelegateTo");
	if (el) {
		/*
		 * msDS-AllowedToDelegateTo is incredibly powerful,
		 * given that it allows a server to become ANY USER on
		 * the target server only listed by SPN so needs to be
		 * protected just as the userAccountControl
		 * UF_TRUSTED_FOR_DELEGATION is.
		 */

		bool have_priv = security_token_has_privilege(user_token,
							      SEC_PRIV_ENABLE_DELEGATION);
		if (have_priv == false) {
			ldb_asprintf_errstring(ldb_module_get_ctx(ac->module),
					       "msDS-AllowedToDelegateTo "
					       "(entry %s) cannot be created "
					       "or changed without SePrivEnableDelegation!",
					       ldb_dn_get_linearized(ac->msg->dn));
			return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
		}
	}
	return LDB_SUCCESS;
}
/* add */
static int samldb_add(struct ldb_module *module, struct ldb_request *req)
{
	struct ldb_context *ldb;
	struct samldb_ctx *ac;
	struct ldb_message_element *el;
	int ret;
	char *referral = NULL;

	ldb = ldb_module_get_ctx(module);
	ldb_debug(ldb, LDB_DEBUG_TRACE, "samldb_add\n");

	/* do not manipulate our control entries */
	if (ldb_dn_is_special(req->op.add.message->dn)) {
		return ldb_next_request(module, req);
	}

	referral = refer_if_rodc(ldb, req, req->op.add.message->dn);
	if (referral != NULL) {
		ret = ldb_module_send_referral(req, referral);
		return ret;
	}

	el = ldb_msg_find_element(req->op.add.message, "userParameters");
	if (el != NULL && ldb_req_is_untrusted(req)) {
		const char *reason = "samldb_add: "
			"setting userParameters is not supported over LDAP, "
			"see https://bugzilla.samba.org/show_bug.cgi?id=8077";
		ldb_debug(ldb, LDB_DEBUG_WARNING, "%s", reason);
		return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION, reason);
	}

	ac = samldb_ctx_init(module, req);
	if (ac == NULL) {
		return ldb_operr(ldb);
	}

	/* build the new msg */
	ac->msg = ldb_msg_copy_shallow(ac, req->op.add.message);
	if (ac->msg == NULL) {
		talloc_free(ac);
		ldb_debug(ldb, LDB_DEBUG_FATAL,
			  "samldb_add: ldb_msg_copy_shallow failed!\n");
		return ldb_operr(ldb);
	}

	ret = samldb_check_sensitive_attributes(ac);
	if (ret != LDB_SUCCESS) {
		talloc_free(ac);
		return ret;
	}

	el = ldb_msg_find_element(ac->msg, "fSMORoleOwner");
	if (el != NULL) {
		ret = samldb_fsmo_role_owner_check(ac);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	el = ldb_msg_find_element(ac->msg, "servicePrincipalName");
	if ((el != NULL)) {
		/*
		 * We need to check whether the SPN collides with an existing
		 * one (anywhere) including via aliases.
		 */
		ret = samldb_spn_uniqueness_check(ac, el);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	if (samdb_find_attribute(ldb, ac->msg,
				 "objectclass", "user") != NULL) {
		ac->type = SAMLDB_TYPE_USER;

		ret = samldb_prim_group_trigger(ac);
		if (ret != LDB_SUCCESS) {
			return ret;
		}

		ret = samldb_objectclass_trigger(ac);
		if (ret != LDB_SUCCESS) {
			return ret;
		}

		return samldb_fill_object(ac);
	}

	if (samdb_find_attribute(ldb, ac->msg,
				 "objectclass", "group") != NULL) {
		ac->type = SAMLDB_TYPE_GROUP;

		ret = samldb_objectclass_trigger(ac);
		if (ret != LDB_SUCCESS) {
			return ret;
		}

		return samldb_fill_object(ac);
	}

	/* perhaps a foreignSecurityPrincipal? */
	if (samdb_find_attribute(ldb, ac->msg,
				 "objectclass",
				 "foreignSecurityPrincipal") != NULL) {
		return samldb_fill_foreignSecurityPrincipal_object(ac);
	}

	if (samdb_find_attribute(ldb, ac->msg,
				 "objectclass", "classSchema") != NULL) {
		ac->type = SAMLDB_TYPE_CLASS;

		/* If in provision, these checks are too slow to do */
		if (!ldb_request_get_control(req, DSDB_CONTROL_SKIP_DUPLICATES_CHECK_OID)) {
			ret = samldb_schema_governsid_valid_check(ac);
			if (ret != LDB_SUCCESS) {
				return ret;
			}
		}

		ret = samldb_schema_ldapdisplayname_valid_check(ac);
		if (ret != LDB_SUCCESS) {
			return ret;
		}

		ret = samldb_schema_info_update(ac);
		if (ret != LDB_SUCCESS) {
			talloc_free(ac);
			return ret;
		}

		return samldb_fill_object(ac);
	}

	if (samdb_find_attribute(ldb, ac->msg,
				 "objectclass", "attributeSchema") != NULL) {
		ac->type = SAMLDB_TYPE_ATTRIBUTE;

		/* If in provision, these checks are too slow to do */
		if (!ldb_request_get_control(req, DSDB_CONTROL_SKIP_DUPLICATES_CHECK_OID)) {
			ret = samldb_schema_attributeid_valid_check(ac);
			if (ret != LDB_SUCCESS) {
				return ret;
			}

			ret = samldb_schema_add_handle_linkid(ac);
			if (ret != LDB_SUCCESS) {
				return ret;
			}

			ret = samldb_schema_add_handle_mapiid(ac);
			if (ret != LDB_SUCCESS) {
				return ret;
			}
		}

		ret = samldb_schema_ldapdisplayname_valid_check(ac);
		if (ret != LDB_SUCCESS) {
			return ret;
		}

		ret = samldb_schema_info_update(ac);
		if (ret != LDB_SUCCESS) {
			talloc_free(ac);
			return ret;
		}

		return samldb_fill_object(ac);
	}

	if (samdb_find_attribute(ldb, ac->msg,
				 "objectclass", "subnet") != NULL) {
		ret = samldb_verify_subnet(ac, ac->msg->dn);
		if (ret != LDB_SUCCESS) {
			talloc_free(ac);
			return ret;
		}
		/* We are just checking the value is valid, and there are no
		   values to fill in. */
	}

	talloc_free(ac);

	/* nothing matched, go on */
	return ldb_next_request(module, req);
}

/* modify */
static int samldb_modify(struct ldb_module *module, struct ldb_request *req)
{
	struct ldb_context *ldb;
	struct samldb_ctx *ac;
	struct ldb_message_element *el, *el2;
	struct ldb_control *is_undelete;
	bool modified = false;
	int ret;

	if (ldb_dn_is_special(req->op.mod.message->dn)) {
		/* do not manipulate our control entries */
		return ldb_next_request(module, req);
	}

	ldb = ldb_module_get_ctx(module);

	/*
	 * we are going to need some special handling if in Undelete call.
	 * Since tombstone_reanimate module will restore certain attributes,
	 * we need to relax checks for: sAMAccountType, primaryGroupID
	 */
	is_undelete = ldb_request_get_control(req, DSDB_CONTROL_RESTORE_TOMBSTONE_OID);

	/* make sure that "objectSid" is not specified */
	el = ldb_msg_find_element(req->op.mod.message, "objectSid");
	if (el != NULL) {
		if (ldb_request_get_control(req, LDB_CONTROL_PROVISION_OID) == NULL) {
			ldb_set_errstring(ldb,
					  "samldb: objectSid must not be specified!");
			return LDB_ERR_UNWILLING_TO_PERFORM;
		}
	}
	if (is_undelete == NULL) {
		/* make sure that "sAMAccountType" is not specified */
		el = ldb_msg_find_element(req->op.mod.message, "sAMAccountType");
		if (el != NULL) {
			ldb_set_errstring(ldb,
					  "samldb: sAMAccountType must not be specified!");
			return LDB_ERR_UNWILLING_TO_PERFORM;
		}
	}
	/* make sure that "isCriticalSystemObject" is not specified */
	el = ldb_msg_find_element(req->op.mod.message, "isCriticalSystemObject");
	if (el != NULL) {
		if (ldb_request_get_control(req, LDB_CONTROL_RELAX_OID) == NULL) {
			ldb_set_errstring(ldb,
					  "samldb: isCriticalSystemObject must not be specified!");
			return LDB_ERR_UNWILLING_TO_PERFORM;
		}
	}

	/* msDS-IntId is not allowed to be modified
	 * except when modification comes from replication */
	if (ldb_msg_find_element(req->op.mod.message, "msDS-IntId")) {
		if (!ldb_request_get_control(req,
					     DSDB_CONTROL_REPLICATED_UPDATE_OID)) {
			return LDB_ERR_CONSTRAINT_VIOLATION;
		}
	}

	el = ldb_msg_find_element(req->op.mod.message, "userParameters");
	if (el != NULL && ldb_req_is_untrusted(req)) {
		const char *reason = "samldb: "
			"setting userParameters is not supported over LDAP, "
			"see https://bugzilla.samba.org/show_bug.cgi?id=8077";
		ldb_debug(ldb, LDB_DEBUG_WARNING, "%s", reason);
		return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION, reason);
	}

	ac = samldb_ctx_init(module, req);
	if (ac == NULL) {
		return ldb_operr(ldb);
	}

	/* build the new msg */
	ac->msg = ldb_msg_copy_shallow(ac, req->op.mod.message);
	if (ac->msg == NULL) {
		talloc_free(ac);
		ldb_debug(ldb, LDB_DEBUG_FATAL,
			  "samldb_modify: ldb_msg_copy_shallow failed!\n");
		return ldb_operr(ldb);
	}

	ret = samldb_check_sensitive_attributes(ac);
	if (ret != LDB_SUCCESS) {
		talloc_free(ac);
		return ret;
	}

	if (is_undelete == NULL) {
		el = ldb_msg_find_element(ac->msg, "primaryGroupID");
		if (el != NULL) {
			ret = samldb_prim_group_trigger(ac);
			if (ret != LDB_SUCCESS) {
				return ret;
			}
		}
	}

	el = ldb_msg_find_element(ac->msg, "userAccountControl");
	if (el != NULL) {
		modified = true;
		ret = samldb_user_account_control_change(ac);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	el = ldb_msg_find_element(ac->msg, "pwdLastSet");
	if (el != NULL) {
		modified = true;
		ret = samldb_pwd_last_set_change(ac);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	el = ldb_msg_find_element(ac->msg, "lockoutTime");
	if (el != NULL) {
		modified = true;
		ret = samldb_lockout_time(ac);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	el = ldb_msg_find_element(ac->msg, "groupType");
	if (el != NULL) {
		modified = true;
		ret = samldb_group_type_change(ac);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	el = ldb_msg_find_element(ac->msg, "sAMAccountName");
	if (el != NULL) {
		uint32_t user_account_control;
		struct ldb_result *res = NULL;
		const char * const attrs[] = { "userAccountControl",
					       "objectclass",
					       NULL };
		ret = dsdb_module_search_dn(ac->module,
					    ac,
					    &res,
					    ac->msg->dn,
					    attrs,
					    DSDB_FLAG_NEXT_MODULE | DSDB_SEARCH_SHOW_DELETED,
					    ac->req);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
		user_account_control
			= ldb_msg_find_attr_as_uint(res->msgs[0],
						    "userAccountControl",
						    0);

		if ((user_account_control
		     & UF_TRUST_ACCOUNT_MASK) != 0) {
			ac->need_trailing_dollar = true;

		} else if (samdb_find_attribute(ldb,
						res->msgs[0],
						"objectclass",
						"computer")
			   != NULL) {
			ac->need_trailing_dollar = true;
		}

		ret = samldb_sam_accountname_valid_check(ac);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	el = ldb_msg_find_element(ac->msg, "userPrincipalName");
	if (el != NULL) {
		ret = samldb_sam_account_upn_clash(ac);
		if (ret != LDB_SUCCESS) {
			talloc_free(ac);
			return ret;
		}
	}

	el = ldb_msg_find_element(ac->msg, "ldapDisplayName");
	if (el != NULL) {
		ret = samldb_schema_ldapdisplayname_valid_check(ac);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	el = ldb_msg_find_element(ac->msg, "attributeID");
	if (el != NULL) {
		ldb_asprintf_errstring(ldb_module_get_ctx(ac->module),
				       "Once set, attributeID values may not be modified");
		return LDB_ERR_CONSTRAINT_VIOLATION;
	}

	el = ldb_msg_find_element(ac->msg, "governsID");
	if (el != NULL) {
		ldb_asprintf_errstring(ldb_module_get_ctx(ac->module),
				       "Once set, governsID values may not be modified");
		return LDB_ERR_CONSTRAINT_VIOLATION;
	}

	el = ldb_msg_find_element(ac->msg, "member");
	if (el != NULL) {
		struct ldb_control *fix_link_sid_ctrl = NULL;

		fix_link_sid_ctrl = ldb_request_get_control(ac->req,
					DSDB_CONTROL_DBCHECK_FIX_LINK_DN_SID);
		if (fix_link_sid_ctrl == NULL) {
			ret = samldb_member_check(ac);
			if (ret != LDB_SUCCESS) {
				return ret;
			}
		}
	}

	el = ldb_msg_find_element(ac->msg, "description");
	if (el != NULL) {
		ret = samldb_description_check(ac, &modified);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	el = ldb_msg_find_element(ac->msg, "dNSHostName");
	el2 = ldb_msg_find_element(ac->msg, "sAMAccountName");
	if ((el != NULL) || (el2 != NULL)) {
		modified = true;
		/*
		 * samldb_service_principal_names_change() might add SPN
		 * changes to the request, so this must come before the SPN
		 * uniqueness check below.
		 *
		 * Note we ALSO have to do the SPN uniqueness check inside
		 * samldb_service_principal_names_change(), because it does a
		 * subrequest to do requested SPN modifications *before* its
		 * automatic ones are added.
		 */
		ret = samldb_service_principal_names_change(ac);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	el = ldb_msg_find_element(ac->msg, "servicePrincipalName");
	if ((el != NULL)) {
		/*
		 * We need to check whether the SPN collides with an existing
		 * one (anywhere) including via aliases.
		 */
		modified = true;
		ret = samldb_spn_uniqueness_check(ac, el);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	el = ldb_msg_find_element(ac->msg, "fSMORoleOwner");
	if (el != NULL) {
		ret = samldb_fsmo_role_owner_check(ac);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	if (modified) {
		struct ldb_request *child_req;

		/* Now perform the real modifications as a child request */
		ret = ldb_build_mod_req(&child_req, ldb, ac,
					ac->msg,
					req->controls,
					req, dsdb_next_callback,
					req);
		LDB_REQ_SET_LOCATION(child_req);
		if (ret != LDB_SUCCESS) {
			return ret;
		}

		return ldb_next_request(module, child_req);
	}

	talloc_free(ac);

	/* no change which interests us, go on */
	return ldb_next_request(module, req);
}

/* delete */

static int samldb_prim_group_users_check(struct samldb_ctx *ac)
{
	struct ldb_context *ldb;
	struct dom_sid *sid;
	uint32_t rid;
	NTSTATUS status;
	int ret;
	struct ldb_result *res = NULL;
	struct ldb_result *res_users = NULL;
	const char * const attrs[] = { "objectSid", "isDeleted", NULL };
	const char * const noattrs[] = { NULL };

	ldb = ldb_module_get_ctx(ac->module);

	/* Finds out the SID/RID of the SAM object */
	ret = dsdb_module_search_dn(ac->module, ac, &res, ac->req->op.del.dn,
					attrs,
					DSDB_FLAG_NEXT_MODULE | DSDB_SEARCH_SHOW_DELETED,
					ac->req);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	if (ldb_msg_check_string_attribute(res->msgs[0], "isDeleted", "TRUE")) {
		return LDB_SUCCESS;
	}

	sid = samdb_result_dom_sid(ac, res->msgs[0], "objectSid");
	if (sid == NULL) {
		/* No SID - it might not be a SAM object - therefore ok */
		return LDB_SUCCESS;
	}
	status = dom_sid_split_rid(ac, sid, NULL, &rid);
	if (!NT_STATUS_IS_OK(status)) {
		return ldb_operr(ldb);
	}
	if (rid == 0) {
		/* Special object (security principal?) */
		return LDB_SUCCESS;
	}
	/* do not allow deletion of well-known sids */
	if (rid < DSDB_SAMDB_MINIMUM_ALLOWED_RID &&
	    (ldb_request_get_control(ac->req, LDB_CONTROL_RELAX_OID) == NULL)) {
		return LDB_ERR_OTHER;
	}

	/* Deny delete requests from groups which are primary ones */
	ret = dsdb_module_search(ac->module, ac, &res_users,
				 ldb_get_default_basedn(ldb),
				 LDB_SCOPE_SUBTREE, noattrs,
				 DSDB_FLAG_NEXT_MODULE,
				 ac->req,
				 "(&(primaryGroupID=%u)(objectClass=user))", rid);
	if (ret != LDB_SUCCESS) {
		return ret;
	}
	if (res_users->count > 0) {
		ldb_asprintf_errstring(ldb_module_get_ctx(ac->module),
				       "Refusing to delete %s, as it "
				       "is still the primaryGroupID "
				       "for %u users",
				       ldb_dn_get_linearized(res->msgs[0]->dn),
				       res_users->count);

		/*
		 * Yes, this seems very wrong, but we have a test
		 * for this exact error code in sam.py
		 */
		return LDB_ERR_ENTRY_ALREADY_EXISTS;
	}

	return LDB_SUCCESS;
}

static int samldb_delete(struct ldb_module *module, struct ldb_request *req)
{
	struct samldb_ctx *ac;
	char *referral = NULL;
	int ret;
	struct ldb_context *ldb;

	if (ldb_dn_is_special(req->op.del.dn)) {
		/* do not manipulate our control entries */
		return ldb_next_request(module, req);
	}

	ldb = ldb_module_get_ctx(module);

	referral = refer_if_rodc(ldb, req, req->op.del.dn);
	if (referral != NULL) {
		ret = ldb_module_send_referral(req, referral);
		return ret;
	}

	ac = samldb_ctx_init(module, req);
	if (ac == NULL) {
		return ldb_operr(ldb_module_get_ctx(module));
	}

	ret = samldb_prim_group_users_check(ac);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	talloc_free(ac);

	return ldb_next_request(module, req);
}

/* rename */

static int check_rename_constraints(struct ldb_message *msg,
				    struct samldb_ctx *ac,
				    struct ldb_dn *olddn, struct ldb_dn *newdn)
{
	struct ldb_context *ldb = ldb_module_get_ctx(ac->module);
	struct ldb_dn *dn1, *dn2, *nc_root;
	int32_t systemFlags;
	bool move_op = false;
	bool rename_op = false;
	int ret;

	/* Skip the checks if old and new DN are the same, or if we have the
	 * relax control specified or if the returned objects is already
	 * deleted and needs only to be moved for consistency. */

	if (ldb_dn_compare(olddn, newdn) == 0) {
		return LDB_SUCCESS;
	}
	if (ldb_request_get_control(ac->req, LDB_CONTROL_RELAX_OID) != NULL) {
		return LDB_SUCCESS;
	}

	if (ldb_msg_find_attr_as_bool(msg, "isDeleted", false)) {
		/*
		 * check originating request if we are supposed
		 * to "see" this record in first place.
		 */
		if (ldb_request_get_control(ac->req, LDB_CONTROL_SHOW_DELETED_OID) == NULL) {
			return LDB_ERR_NO_SUCH_OBJECT;
		}
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	/* Objects under CN=System */

	dn1 = samdb_system_container_dn(ldb, ac);
	if (dn1 == NULL) return ldb_oom(ldb);

	if ((ldb_dn_compare_base(dn1, olddn) == 0) &&
	    (ldb_dn_compare_base(dn1, newdn) != 0)) {
		talloc_free(dn1);
		ldb_asprintf_errstring(ldb,
				       "subtree_rename: Cannot move/rename %s. Objects under CN=System have to stay under it!",
				       ldb_dn_get_linearized(olddn));
		return LDB_ERR_OTHER;
	}

	talloc_free(dn1);

	/* LSA objects */

	if ((samdb_find_attribute(ldb, msg, "objectClass", "secret") != NULL) ||
	    (samdb_find_attribute(ldb, msg, "objectClass", "trustedDomain") != NULL)) {
		ldb_asprintf_errstring(ldb,
				       "subtree_rename: Cannot move/rename %s. It's an LSA-specific object!",
				       ldb_dn_get_linearized(olddn));
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	/* subnet objects */
	if (samdb_find_attribute(ldb, msg, "objectclass", "subnet") != NULL) {
		ret = samldb_verify_subnet(ac, newdn);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	/* systemFlags */

	dn1 = ldb_dn_get_parent(ac, olddn);
	if (dn1 == NULL) return ldb_oom(ldb);
	dn2 = ldb_dn_get_parent(ac, newdn);
	if (dn2 == NULL) return ldb_oom(ldb);

	if (ldb_dn_compare(dn1, dn2) == 0) {
		rename_op = true;
	} else {
		move_op = true;
	}

	talloc_free(dn1);
	talloc_free(dn2);

	systemFlags = ldb_msg_find_attr_as_int(msg, "systemFlags", 0);

	/* Fetch name context */

	ret = dsdb_find_nc_root(ldb, ac, olddn, &nc_root);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	if (ldb_dn_compare(nc_root, ldb_get_schema_basedn(ldb)) == 0) {
		if (move_op) {
			ldb_asprintf_errstring(ldb,
					       "subtree_rename: Cannot move %s within schema partition",
					       ldb_dn_get_linearized(olddn));
			return LDB_ERR_UNWILLING_TO_PERFORM;
		}
		if (rename_op &&
		    (systemFlags & SYSTEM_FLAG_SCHEMA_BASE_OBJECT) != 0) {
			ldb_asprintf_errstring(ldb,
					       "subtree_rename: Cannot rename %s within schema partition",
					       ldb_dn_get_linearized(olddn));
			return LDB_ERR_UNWILLING_TO_PERFORM;
		}
	} else if (ldb_dn_compare(nc_root, ldb_get_config_basedn(ldb)) == 0) {
		if (move_op &&
		    (systemFlags & SYSTEM_FLAG_CONFIG_ALLOW_MOVE) == 0) {
			/* Here we have to do more: control the
			 * "ALLOW_LIMITED_MOVE" flag. This means that the
			 * grand-grand-parents of two objects have to be equal
			 * in order to perform the move (this is used for
			 * moving "server" objects in the "sites" container). */
			bool limited_move =
				systemFlags & SYSTEM_FLAG_CONFIG_ALLOW_LIMITED_MOVE;

			if (limited_move) {
				dn1 = ldb_dn_copy(ac, olddn);
				if (dn1 == NULL) return ldb_oom(ldb);
				dn2 = ldb_dn_copy(ac, newdn);
				if (dn2 == NULL) return ldb_oom(ldb);

				limited_move &= ldb_dn_remove_child_components(dn1, 3);
				limited_move &= ldb_dn_remove_child_components(dn2, 3);
				limited_move &= ldb_dn_compare(dn1, dn2) == 0;

				talloc_free(dn1);
				talloc_free(dn2);
			}

			if (!limited_move
			    && ldb_request_get_control(ac->req, DSDB_CONTROL_RESTORE_TOMBSTONE_OID) == NULL) {
				ldb_asprintf_errstring(ldb,
						       "subtree_rename: Cannot move %s to %s in config partition",
						       ldb_dn_get_linearized(olddn), ldb_dn_get_linearized(newdn));
				return LDB_ERR_UNWILLING_TO_PERFORM;
			}
		}
		if (rename_op &&
		    (systemFlags & SYSTEM_FLAG_CONFIG_ALLOW_RENAME) == 0) {
			ldb_asprintf_errstring(ldb,
					       "subtree_rename: Cannot rename %s to %s within config partition",
					       ldb_dn_get_linearized(olddn), ldb_dn_get_linearized(newdn));
			return LDB_ERR_UNWILLING_TO_PERFORM;
		}
	} else if (ldb_dn_compare(nc_root, ldb_get_default_basedn(ldb)) == 0) {
		if (move_op &&
		    (systemFlags & SYSTEM_FLAG_DOMAIN_DISALLOW_MOVE) != 0) {
			ldb_asprintf_errstring(ldb,
					       "subtree_rename: Cannot move %s to %s - DISALLOW_MOVE set",
					       ldb_dn_get_linearized(olddn), ldb_dn_get_linearized(newdn));
			return LDB_ERR_UNWILLING_TO_PERFORM;
		}
		if (rename_op &&
		    (systemFlags & SYSTEM_FLAG_DOMAIN_DISALLOW_RENAME) != 0) {
			ldb_asprintf_errstring(ldb,
						       "subtree_rename: Cannot rename %s to %s - DISALLOW_RENAME set",
					       ldb_dn_get_linearized(olddn), ldb_dn_get_linearized(newdn));
			return LDB_ERR_UNWILLING_TO_PERFORM;
		}
	}

	talloc_free(nc_root);

	return LDB_SUCCESS;
}


static int samldb_rename_search_base_callback(struct ldb_request *req,
					       struct ldb_reply *ares)
{
	struct samldb_ctx *ac;
	int ret;

	ac = talloc_get_type(req->context, struct samldb_ctx);

	if (!ares) {
		return ldb_module_done(ac->req, NULL, NULL,
					LDB_ERR_OPERATIONS_ERROR);
	}
	if (ares->error != LDB_SUCCESS) {
		return ldb_module_done(ac->req, ares->controls,
					ares->response, ares->error);
	}

	switch (ares->type) {
	case LDB_REPLY_ENTRY:
		/*
		 * This is the root entry of the originating move
		 * respectively rename request. It has been already
		 * stored in the list using "subtree_rename_search()".
		 * Only this one is subject to constraint checking.
		 */
		ret = check_rename_constraints(ares->message, ac,
					       ac->req->op.rename.olddn,
					       ac->req->op.rename.newdn);
		if (ret != LDB_SUCCESS) {
			return ldb_module_done(ac->req, NULL, NULL,
					       ret);
		}
		break;

	case LDB_REPLY_REFERRAL:
		/* ignore */
		break;

	case LDB_REPLY_DONE:

		/*
		 * Great, no problem with the rename, so go ahead as
		 * if we never were here
		 */
		ret = ldb_next_request(ac->module, ac->req);
		talloc_free(ares);
		return ret;
	}

	talloc_free(ares);
	return LDB_SUCCESS;
}


/* rename */
static int samldb_rename(struct ldb_module *module, struct ldb_request *req)
{
	struct ldb_context *ldb;
	static const char * const attrs[] = { "objectClass", "systemFlags",
					      "isDeleted", NULL };
	struct ldb_request *search_req;
	struct samldb_ctx *ac;
	int ret;

	if (ldb_dn_is_special(req->op.rename.olddn)) { /* do not manipulate our control entries */
		return ldb_next_request(module, req);
	}

	ldb = ldb_module_get_ctx(module);

	ac = samldb_ctx_init(module, req);
	if (!ac) {
		return ldb_oom(ldb);
	}

	ret = ldb_build_search_req(&search_req, ldb, ac,
				   req->op.rename.olddn,
				   LDB_SCOPE_BASE,
				   "(objectClass=*)",
				   attrs,
				   NULL,
				   ac,
				   samldb_rename_search_base_callback,
				   req);
	LDB_REQ_SET_LOCATION(search_req);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	ret = ldb_request_add_control(search_req, LDB_CONTROL_SHOW_RECYCLED_OID,
				      true, NULL);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	return ldb_next_request(ac->module, search_req);
}

/* extended */

static int samldb_extended_allocate_rid_pool(struct ldb_module *module, struct ldb_request *req)
{
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct dsdb_fsmo_extended_op *exop;
	int ret;

	exop = talloc_get_type(req->op.extended.data,
			       struct dsdb_fsmo_extended_op);
	if (!exop) {
		ldb_set_errstring(ldb,
				  "samldb_extended_allocate_rid_pool: invalid extended data");
		return LDB_ERR_PROTOCOL_ERROR;
	}

	ret = ridalloc_allocate_rid_pool_fsmo(module, exop, req);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	return ldb_module_done(req, NULL, NULL, LDB_SUCCESS);
}

static int samldb_extended_allocate_rid(struct ldb_module *module, struct ldb_request *req)
{
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct dsdb_extended_allocate_rid *exop;
	int ret;

	exop = talloc_get_type(req->op.extended.data,
			       struct dsdb_extended_allocate_rid);
	if (!exop) {
		ldb_set_errstring(ldb,
				  "samldb_extended_allocate_rid: invalid extended data");
		return LDB_ERR_PROTOCOL_ERROR;
	}

	ret = ridalloc_allocate_rid(module, &exop->rid, req);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	return ldb_module_done(req, NULL, NULL, LDB_SUCCESS);
}

static int samldb_extended_create_own_rid_set(struct ldb_module *module, struct ldb_request *req)
{
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	int ret;
	struct ldb_dn *dn;

	if (req->op.extended.data != NULL) {
		ldb_set_errstring(ldb,
				  "samldb_extended_create_own_rid_set: invalid extended data (should be NULL)");
		return LDB_ERR_PROTOCOL_ERROR;
	}

	ret = ridalloc_create_own_rid_set(module, req,
					  &dn, req);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	return ldb_module_done(req, NULL, NULL, LDB_SUCCESS);
}

static int samldb_extended(struct ldb_module *module, struct ldb_request *req)
{
	if (strcmp(req->op.extended.oid, DSDB_EXTENDED_ALLOCATE_RID_POOL) == 0) {
		return samldb_extended_allocate_rid_pool(module, req);
	}

	if (strcmp(req->op.extended.oid, DSDB_EXTENDED_ALLOCATE_RID) == 0) {
		return samldb_extended_allocate_rid(module, req);
	}

	if (strcmp(req->op.extended.oid, DSDB_EXTENDED_CREATE_OWN_RID_SET) == 0) {
		return samldb_extended_create_own_rid_set(module, req);
	}

	return ldb_next_request(module, req);
}


static const struct ldb_module_ops ldb_samldb_module_ops = {
	.name          = "samldb",
	.add           = samldb_add,
	.modify        = samldb_modify,
	.del           = samldb_delete,
	.rename        = samldb_rename,
	.extended      = samldb_extended
};


int ldb_samldb_module_init(const char *version)
{
	LDB_MODULE_CHECK_VERSION(version);
	return ldb_register_module(&ldb_samldb_module_ops);
}