1 files changed, 347 insertions, 0 deletions

diff --git a/source4/dsdb/kcc/garbage_collect_tombstones.c b/source4/dsdb/kcc/garbage_collect_tombstones.c
new file mode 100644
index 0000000..14ee2d4
--- /dev/null
+++ b/source4/dsdb/kcc/garbage_collect_tombstones.c
@@ -0,0 +1,347 @@
+/*
+   Unix SMB/CIFS implementation.
+
+   handle removal of deleted objects
+
+   Copyright (C) 2009 Andrew Tridgell
+   Copyright (C) 2016 Andrew Bartlett
+   Copyright (C) 2016 Catalyst.NET Ltd
+
+   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/>.
+
+*/
+
+#include "includes.h"
+#include <ldb_errors.h>
+#include "../lib/util/dlinklist.h"
+#include "librpc/gen_ndr/ndr_misc.h"
+#include "librpc/gen_ndr/ndr_drsuapi.h"
+#include "librpc/gen_ndr/ndr_drsblobs.h"
+#include "param/param.h"
+#include "lib/util/dlinklist.h"
+#include "ldb.h"
+#include "dsdb/kcc/garbage_collect_tombstones.h"
+#include "lib/ldb-samba/ldb_matching_rules.h"
+#include "lib/util/time.h"
+
+static NTSTATUS garbage_collect_tombstones_part(TALLOC_CTX *mem_ctx,
+						struct ldb_context *samdb,
+						struct dsdb_ldb_dn_list_node *part,
+						char *filter,
+						unsigned int *num_links_removed,
+						unsigned int *num_objects_removed,
+						struct dsdb_schema *schema,
+						const char **attrs,
+						char **error_string,
+						NTTIME expunge_time_nttime)
+{
+	int ret;
+	struct ldb_dn *do_dn;
+	struct ldb_result *res;
+	unsigned int i, j, k;
+	uint32_t flags;
+	TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
+	if (!tmp_ctx) {
+		return NT_STATUS_NO_MEMORY;
+	}
+
+	ret = dsdb_get_deleted_objects_dn(samdb, tmp_ctx, part->dn, &do_dn);
+	if (ret != LDB_SUCCESS) {
+		TALLOC_FREE(tmp_ctx);
+		/* some partitions have no Deleted Objects
+		   container */
+		return NT_STATUS_OK;
+	}
+
+	DBG_INFO("Doing a full scan on %s and looking for deleted objects\n",
+		  ldb_dn_get_linearized(part->dn));
+
+	flags = DSDB_SEARCH_SHOW_RECYCLED |
+		DSDB_SEARCH_SHOW_DN_IN_STORAGE_FORMAT |
+		DSDB_SEARCH_REVEAL_INTERNALS;
+	ret = dsdb_search(samdb, tmp_ctx, &res, part->dn, LDB_SCOPE_SUBTREE,
+			  attrs, flags, "%s", filter);
+
+	if (ret != LDB_SUCCESS) {
+		*error_string = talloc_asprintf(mem_ctx,
+						"Failed to search for deleted "
+						"objects in %s: %s",
+						ldb_dn_get_linearized(do_dn),
+						ldb_errstring(samdb));
+		TALLOC_FREE(tmp_ctx);
+		return NT_STATUS_INTERNAL_ERROR;
+	}
+
+	for (i=0; i<res->count; i++) {
+		struct ldb_message *cleanup_msg = NULL;
+		unsigned int num_modified = 0;
+
+		bool isDeleted = ldb_msg_find_attr_as_bool(res->msgs[i],
+							   "isDeleted", false);
+		if (isDeleted) {
+			if (ldb_dn_compare(do_dn, res->msgs[i]->dn) == 0) {
+				/* Skip the Deleted Object Container */
+				continue;
+			}
+
+			ret = dsdb_delete(samdb, res->msgs[i]->dn,
+					  DSDB_SEARCH_SHOW_RECYCLED
+					  |DSDB_MODIFY_RELAX);
+			if (ret != LDB_SUCCESS) {
+				DBG_WARNING(__location__ ": Failed to remove "
+					 "deleted object %s\n",
+					 ldb_dn_get_linearized(res->
+							       msgs[i]->dn));
+			} else {
+				DBG_INFO("Removed deleted object %s\n",
+					 ldb_dn_get_linearized(res->
+							       msgs[i]->dn));
+				(*num_objects_removed)++;
+			}
+			continue;
+		}
+
+		/* This must have a linked attribute */
+
+		/*
+		 * From MS-ADTS 3.1.1.1.9 DCs, usn Counters, and
+		 * the Originating Update Stamp
+		 *
+		 * "A link value r is deleted, but exists as a
+		 *  tombstone, if r.stamp.timeDeleted ≠ 0. When
+		 *  the current time minus r.stamp.timeDeleted
+		 *  exceeds the tombstone lifetime, the link
+		 *  value r is garbage-collected; that is,
+		 *  removed from its containing forward link
+		 *  attribute. "
+		 */
+
+		for (j=0; j < res->msgs[i]->num_elements; j++) {
+			struct ldb_message_element *element = NULL;
+			/* TODO this is O(log n) per attribute with deleted values */
+			const struct dsdb_attribute *attrib = NULL;
+
+			element = &res->msgs[i]->elements[j];
+			attrib = dsdb_attribute_by_lDAPDisplayName(schema,
+								   element->name);
+
+			/* This avoids parsing isDeleted as a link */
+			if (attrib == NULL ||
+			    attrib->linkID == 0 ||
+			    ((attrib->linkID & 1) == 1)) {
+				continue;
+			}
+
+			for (k = 0; k < element->num_values; k++) {
+				struct ldb_val *value = &element->values[k];
+				uint64_t whenChanged = 0;
+				NTSTATUS status;
+				struct dsdb_dn *dn;
+				struct ldb_message_element *cleanup_elem = NULL;
+				char *guid_search_str = NULL;
+				char *guid_buf_str = NULL;
+				struct ldb_val cleanup_val;
+				struct GUID_txt_buf buf_guid;
+				struct GUID guid;
+				const struct ldb_val *guid_blob;
+
+				if (dsdb_dn_is_deleted_val(value) == false) {
+					continue;
+				}
+
+				dn = dsdb_dn_parse(tmp_ctx, samdb,
+						   &element->values[k],
+						   attrib->syntax->ldap_oid);
+				if (dn == NULL) {
+					DBG_WARNING("Failed to parse linked attribute blob of "
+						  "%s on %s while expunging expired links\n",
+						  element->name,
+						  ldb_dn_get_linearized(res->msgs[i]->dn));
+					continue;
+				}
+
+				status = dsdb_get_extended_dn_uint64(dn->dn,
+								     &whenChanged,
+								     "RMD_CHANGETIME");
+				if (!NT_STATUS_IS_OK(status)) {
+					DBG_WARNING("Error: RMD_CHANGETIME is missing on a forward link.\n");
+					talloc_free(dn);
+					continue;
+				}
+
+				if (whenChanged >= expunge_time_nttime) {
+					talloc_free(dn);
+					continue;
+				}
+
+				guid_blob = ldb_dn_get_extended_component(dn->dn, "GUID");
+				status = GUID_from_ndr_blob(guid_blob, &guid);
+				if (!NT_STATUS_IS_OK(status)) {
+					DBG_WARNING("Error: Invalid GUID on link target.\n");
+					talloc_free(dn);
+					continue;
+				}
+
+				guid_buf_str = GUID_buf_string(&guid, &buf_guid);
+				guid_search_str = talloc_asprintf(mem_ctx,
+								  "<GUID=%s>;%s",
+								  guid_buf_str,
+								  dsdb_dn_get_linearized(mem_ctx, dn));
+				cleanup_val = data_blob_string_const(guid_search_str);
+
+				talloc_free(dn);
+
+				if (cleanup_msg == NULL) {
+					cleanup_msg = ldb_msg_new(mem_ctx);
+					if (cleanup_msg == NULL) {
+						return NT_STATUS_NO_MEMORY;
+					}
+					cleanup_msg->dn = res->msgs[i]->dn;
+				}
+
+				ret = ldb_msg_add_value(cleanup_msg,
+							element->name,
+							&cleanup_val,
+							&cleanup_elem);
+				if (ret != LDB_SUCCESS) {
+					return NT_STATUS_NO_MEMORY;
+				}
+				cleanup_elem->flags = LDB_FLAG_MOD_DELETE;
+				num_modified++;
+			}
+		}
+
+		if (num_modified > 0) {
+			ret = dsdb_modify(samdb, cleanup_msg,
+					  DSDB_REPLMD_VANISH_LINKS);
+			if (ret != LDB_SUCCESS) {
+				DBG_WARNING(__location__ ": Failed to remove deleted object %s\n",
+					 ldb_dn_get_linearized(res->msgs[i]->dn));
+			} else {
+				DBG_INFO("Removed deleted object %s\n",
+					 ldb_dn_get_linearized(res->msgs[i]->dn));
+				*num_links_removed = *num_links_removed + num_modified;
+			}
+
+		}
+	}
+
+	TALLOC_FREE(tmp_ctx);
+	return NT_STATUS_OK;
+}
+
+/*
+ * Per MS-ADTS 3.1.1.5.5 Delete Operation
+ *
+ * "Tombstones are a type of deleted object distinguished from
+ *  existing-objects by the presence of the isDeleted attribute with the
+ *  value true."
+ *
+ * "After a time period at least as large as a tombstone lifetime, the
+ *  tombstone is removed from the directory."
+ *
+ * The purpose of this routine is to remove such objects.  It is
+ * called from a timed event in the KCC, and from samba-tool domain
+ * expunge tombstones.
+ *
+ * Additionally, linked attributes have similar properties.
+ */
+NTSTATUS dsdb_garbage_collect_tombstones(TALLOC_CTX *mem_ctx,
+					 struct ldb_context *samdb,
+					 struct dsdb_ldb_dn_list_node *part,
+					 time_t current_time,
+					 uint32_t tombstoneLifetime,
+					 unsigned int *num_objects_removed,
+					 unsigned int *num_links_removed,
+					 char **error_string)
+{
+	const char **attrs = NULL;
+	char *filter = NULL;
+	NTSTATUS status;
+	unsigned int i;
+	struct dsdb_attribute *next_attr;
+	unsigned int num_link_attrs;
+	struct dsdb_schema *schema = dsdb_get_schema(samdb, mem_ctx);
+	unsigned long long expunge_time = current_time - tombstoneLifetime*60*60*24;
+	char *expunge_time_string = ldb_timestring_utc(mem_ctx, expunge_time);
+	NTTIME expunge_time_nttime;
+	unix_to_nt_time(&expunge_time_nttime, expunge_time);
+
+	*num_objects_removed = 0;
+	*num_links_removed = 0;
+	*error_string = NULL;
+	num_link_attrs = 0;
+
+	/*
+	 * This filter is a bit strange, but the idea is to filter for
+	 * objects that need to have tombstones expunged without
+	 * bringing a potentially large database all into memory.  To
+	 * do that, we could use callbacks, but instead we use a
+	 * custom match rule to triage the objects during the search,
+	 * and ideally avoid memory allocation for most of the
+	 * un-matched objects.
+	 *
+	 * The parameter to DSDB_MATCH_FOR_EXPUNGE is the NTTIME, we
+	 * return records with deleted links deleted before this time.
+	 *
+	 * We use a date comparison on whenChanged to avoid returning
+	 * all isDeleted records
+	 */
+
+	filter = talloc_asprintf(mem_ctx, "(|");
+	for (next_attr = schema->attributes; next_attr != NULL; next_attr = next_attr->next) {
+		if (next_attr->linkID != 0 && ((next_attr->linkID & 1) == 0)) {
+			num_link_attrs++;
+			filter = talloc_asprintf_append(filter,
+							"(%s:" DSDB_MATCH_FOR_EXPUNGE ":=%llu)",
+							next_attr->lDAPDisplayName,
+							(unsigned long long)expunge_time_nttime);
+			if (filter == NULL) {
+				return NT_STATUS_NO_MEMORY;
+			}
+		}
+	}
+
+	attrs = talloc_array(mem_ctx, const char *, num_link_attrs + 2);
+	i = 0;
+	for (next_attr = schema->attributes; next_attr != NULL; next_attr = next_attr->next) {
+		if (next_attr->linkID != 0 && ((next_attr->linkID & 1) == 0)) {
+			attrs[i++] = next_attr->lDAPDisplayName;
+		}
+	}
+	attrs[i] = "isDeleted";
+	attrs[i+1] = NULL;
+
+	filter = talloc_asprintf_append(filter,
+					"(&(isDeleted=TRUE)(whenChanged<=%s)))",
+					expunge_time_string);
+	if (filter == NULL) {
+		return NT_STATUS_NO_MEMORY;
+	}
+
+	for (; part != NULL; part = part->next) {
+		status = garbage_collect_tombstones_part(mem_ctx, samdb, part,
+							 filter,
+							 num_links_removed,
+							 num_objects_removed,
+							 schema, attrs,
+							 error_string,
+							 expunge_time_nttime);
+		if (!NT_STATUS_IS_OK(status)) {
+			return status;
+		}
+	}
+
+	return NT_STATUS_OK;
+}