r25942: Make various ldb modules handle an LDB backend that enforces validity

of Base DNs in searches (returning an error of LDB_ERR_NO_SUCH_ENTRY).

We need to handle this if ldb_tdb is to behave correctly compared with
LDAP, as well as if we are using an LDAP backend.

In doing so, I realised that subtree_rename and subtree_delete
(prevention) need rather different wait loops, so it seemed easier to
split it out into it's own module.

I've fixed the licence on both of these modules to be GPLv3.

Andrew Bartlett
(This used to be commit d3894c90f31fb45e038ab478cd9d7d34962d069b)

1 files changed, 255 insertions, 0 deletions

diff --git a/source4/dsdb/samdb/ldb_modules/subtree_delete.c b/source4/dsdb/samdb/ldb_modules/subtree_delete.c
new file mode 100644
index 0000000000..92f539457e
--- /dev/null
+++ b/source4/dsdb/samdb/ldb_modules/subtree_delete.c
@@ -0,0 +1,255 @@
+/* 
+   ldb database library
+
+   Copyright (C) Andrew Bartlett <abartlet@samba.org> 2006-2007
+   Copyright (C) Stefan Metzmacher <metze@samba.org> 2007
+
+   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 subtree delete (prevention) module
+ *
+ *  Description: Prevent deletion of a subtree in LDB
+ *
+ *  Author: Andrew Bartlett
+ */
+
+#include "ldb_includes.h"
+
+struct subtree_delete_context {
+	enum sd_step {SD_SEARCH, SD_DO_DEL} step;
+
+	struct ldb_module *module;
+	struct ldb_handle *handle;
+	struct ldb_request *orig_req;
+
+	struct ldb_request *search_req;
+	struct ldb_request *down_req;
+
+	int num_children;
+};
+
+static struct subtree_delete_context *subtree_delete_init_handle(struct ldb_request *req, 
+								 struct ldb_module *module)
+{
+	struct subtree_delete_context *ac;
+	struct ldb_handle *h;
+
+	h = talloc_zero(req, struct ldb_handle);
+	if (h == NULL) {
+		ldb_set_errstring(module->ldb, "Out of Memory");
+		return NULL;
+	}
+
+	h->module = module;
+
+	ac = talloc_zero(h, struct subtree_delete_context);
+	if (ac == NULL) {
+		ldb_set_errstring(module->ldb, "Out of Memory");
+		talloc_free(h);
+		return NULL;
+	}
+
+	h->private_data	= ac;
+
+	ac->module = module;
+	ac->handle = h;
+	ac->orig_req = req;
+
+	req->handle = h;
+
+	return ac;
+}
+
+static int subtree_delete_check_for_children(struct subtree_delete_context *ac)
+{
+	if (ac->num_children > 0) {
+		ldb_asprintf_errstring(ac->module->ldb, "Cannot delete %s, not a leaf node (has %d children)\n",
+				       ldb_dn_get_linearized(ac->orig_req->op.del.dn), ac->num_children);
+		return LDB_ERR_NOT_ALLOWED_ON_NON_LEAF;
+	} else {
+		struct ldb_request *req = talloc(ac, struct ldb_request);
+		if (!req) {
+			ldb_oom(ac->module->ldb);
+			return LDB_ERR_OPERATIONS_ERROR;
+		}
+		*req = *ac->orig_req;
+		
+		ac->down_req = req;
+		ac->step = SD_DO_DEL;
+		return ldb_next_request(ac->module, req);
+	}
+}
+
+static int subtree_delete_search_callback(struct ldb_context *ldb, void *context, struct ldb_reply *ares) 
+{
+	struct subtree_delete_context *ac = talloc_get_type(context, struct subtree_delete_context);
+	TALLOC_CTX *mem_ctx = talloc_new(ac);
+    
+	if (!mem_ctx) {
+		ldb_oom(ac->module->ldb);
+		return LDB_ERR_OPERATIONS_ERROR;
+	}
+	/* OK, we have one of *many* search results here:
+
+	   We should also get the entry we tried to rename.  This
+	   callback handles this and everything below it.
+	 */
+
+	/* Only entries are interesting, and we handle the case of the parent seperatly */
+	if (ares->type == LDB_REPLY_ENTRY
+	    && ldb_dn_compare(ares->message->dn, ac->orig_req->op.del.dn) != 0) {
+		/* And it is an actual entry: now object bitterly that we are not a leaf node */
+		ac->num_children++;
+	}
+	talloc_free(ares);
+	return LDB_SUCCESS;
+}
+
+/* rename */
+static int subtree_delete(struct ldb_module *module, struct ldb_request *req)
+{
+	const char *attrs[] = { NULL };
+	struct ldb_request *new_req;
+	struct subtree_delete_context *ac;
+	int ret;
+	if (ldb_dn_is_special(req->op.rename.olddn)) { /* do not manipulate our control entries */
+		return ldb_next_request(module, req);
+	}
+
+	/* This gets complex:  We need to:
+	   - Do a search for all entires under this entry 
+	   - Wait for these results to appear
+	   - In the callback for each result, count the children (if any)
+	   - return an error if there are any
+	*/
+
+	ac = subtree_delete_init_handle(req, module);
+	if (!ac) {
+		return LDB_ERR_OPERATIONS_ERROR;
+	}
+
+	ret = ldb_build_search_req(&new_req, module->ldb, req,
+				   req->op.del.dn, 
+				   LDB_SCOPE_SUBTREE,
+				   "(objectClass=*)",
+				   attrs,
+				   req->controls,
+				   ac, 
+				   subtree_delete_search_callback);
+
+	if (ret != LDB_SUCCESS) {
+		return ret;
+	}
+
+	ac->search_req = new_req;
+	if (req == NULL) {
+		ldb_oom(ac->module->ldb);
+		return LDB_ERR_OPERATIONS_ERROR;
+	}
+	return ldb_next_request(module, new_req);
+}
+
+
+static int subtree_delete_wait_none(struct ldb_handle *handle) {
+	struct subtree_delete_context *ac;
+	int ret = LDB_ERR_OPERATIONS_ERROR;
+	if (!handle || !handle->private_data) {
+		return LDB_ERR_OPERATIONS_ERROR;
+	}
+
+	if (handle->state == LDB_ASYNC_DONE) {
+		return handle->status;
+	}
+
+	handle->state = LDB_ASYNC_PENDING;
+	handle->status = LDB_SUCCESS;
+
+	ac = talloc_get_type(handle->private_data, struct subtree_delete_context);
+
+	switch (ac->step) {
+	case SD_SEARCH:
+		ret = ldb_wait(ac->search_req->handle, LDB_WAIT_NONE);
+
+		if (ret != LDB_SUCCESS && ret != LDB_ERR_NO_SUCH_OBJECT) {
+			handle->status = ret;
+			goto done;
+		}
+		if (ac->search_req->handle->status != LDB_SUCCESS
+			&& ac->search_req->handle->status != LDB_ERR_NO_SUCH_OBJECT) {
+			handle->status = ac->search_req->handle->status;
+			goto done;
+		}
+
+		return subtree_delete_check_for_children(ac);
+
+	case SD_DO_DEL:
+		ret = ldb_wait(ac->down_req->handle, LDB_WAIT_NONE);
+
+		if (ret != LDB_SUCCESS) {
+			handle->status = ret;
+			goto done;
+		}
+		if (ac->down_req->handle->status != LDB_SUCCESS) {
+			handle->status = ac->down_req->handle->status;
+			goto done;
+		}
+
+		if (ac->down_req->handle->state != LDB_ASYNC_DONE) {
+			return LDB_SUCCESS;
+		}
+
+		break;
+	}
+done:
+	handle->state = LDB_ASYNC_DONE;
+	return ret;
+}
+
+static int subtree_delete_wait_all(struct ldb_handle *handle) {
+
+	int ret;
+
+	while (handle->state != LDB_ASYNC_DONE) {
+		ret = subtree_delete_wait_none(handle);
+		if (ret != LDB_SUCCESS) {
+			return ret;
+		}
+	}
+
+	return handle->status;
+}
+
+static int subtree_delete_wait(struct ldb_handle *handle, enum ldb_wait_type type)
+{
+	if (type == LDB_WAIT_ALL) {
+		return subtree_delete_wait_all(handle);
+	} else {
+		return subtree_delete_wait_none(handle);
+	}
+}
+
+static const struct ldb_module_ops subtree_delete_ops = {
+	.name		   = "subtree_delete",
+	.del               = subtree_delete,
+	.wait              = subtree_delete_wait,
+};
+
+int ldb_subtree_delete_init(void)
+{
+	return ldb_register_module(&subtree_delete_ops);
+}