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[Samba.git] / lib / ldb-samba / ldb_matching_rules.c

/*
   Unix SMB/CIFS implementation.

   ldb database library - Extended match rules

   Copyright (C) 2014 Samuel Cabrero <samuelcabrero@kernevil.me>
   Copyright (C) Andrew Bartlett <abartlet@samba.org>

   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_module.h>
#include "dsdb/samdb/samdb.h"
#include "ldb_matching_rules.h"
#include "libcli/security/security.h"
#include "dsdb/common/util.h"
#include "librpc/gen_ndr/ndr_dnsp.h"

static int ldb_eval_transitive_filter_helper(TALLOC_CTX *mem_ctx,
                                             struct ldb_context *ldb,
                                             const char *attr,
                                             const struct dsdb_dn *dn_to_match,
                                             const char *dn_oid,
                                             struct dsdb_dn *to_visit,
                                             struct dsdb_dn ***visited,
                                             unsigned int *visited_count,
                                             bool *matched)
{
        TALLOC_CTX *tmp_ctx;
        int ret, i, j;
        struct ldb_result *res;
        struct ldb_message *msg;
        struct ldb_message_element *el;
        const char *attrs[] = { attr, NULL };

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

        /*
         * Fetch the entry to_visit
         *
         * NOTE: This is a new LDB search from the TOP of the module
         * stack.  This means that this search runs the whole stack
         * from top to bottom.
         *
         * This may seem to be in-efficient, but it is also the only
         * way to ensure that the ACLs for this search are applied
         * correctly.
         *
         * Note also that we don't have the original request
         * here, so we can not apply controls or timeouts here.
         */
        ret = dsdb_search_dn(ldb, tmp_ctx, &res, to_visit->dn, attrs, 0);
        if (ret != LDB_SUCCESS) {
                talloc_free(tmp_ctx);
                return ret;
        }
        if (res->count != 1) {
                talloc_free(tmp_ctx);
                return LDB_ERR_OPERATIONS_ERROR;
        }
        msg = res->msgs[0];

        /* Fetch the attribute to match from the entry being visited */
        el = ldb_msg_find_element(msg, attr);
        if (el == NULL) {
                /* This entry does not have the attribute to match */
                talloc_free(tmp_ctx);
                *matched = false;
                return LDB_SUCCESS;
        }

        /*
         * If the value to match is present in the attribute values of the
         * current entry being visited, set matched to true and return OK
         */
        for (i=0; i<el->num_values; i++) {
                struct dsdb_dn *dn;
                dn = dsdb_dn_parse(tmp_ctx, ldb, &el->values[i], dn_oid);
                if (dn == NULL) {
                        talloc_free(tmp_ctx);
                        *matched = false;
                        return LDB_ERR_INVALID_DN_SYNTAX;
                }

                if (ldb_dn_compare(dn_to_match->dn, dn->dn) == 0) {
                        talloc_free(tmp_ctx);
                        *matched = true;
                        return LDB_SUCCESS;
                }
        }

        /*
         * If arrived here, the value to match is not in the values of the
         * entry being visited. Add the entry being visited (to_visit)
         * to the visited array. The array is (re)allocated in the parent
         * memory context.
         */
        if (visited == NULL) {
                return LDB_ERR_OPERATIONS_ERROR;
        } else if (*visited == NULL) {
                *visited = talloc_array(mem_ctx, struct dsdb_dn *, 1);
                if (*visited == NULL) {
                        talloc_free(tmp_ctx);
                        return LDB_ERR_OPERATIONS_ERROR;
                }
                (*visited)[0] = to_visit;
                (*visited_count) = 1;
        } else {
                *visited = talloc_realloc(mem_ctx, *visited, struct dsdb_dn *,
                                         (*visited_count) + 1);
                if (*visited == NULL) {
                        talloc_free(tmp_ctx);
                        return LDB_ERR_OPERATIONS_ERROR;
                }
                (*visited)[(*visited_count)] = to_visit;
                (*visited_count)++;
        }

        /*
         * steal to_visit into visited array context, as it has to live until
         * the array is freed.
         */
        talloc_steal(*visited, to_visit);

        /*
         * Iterate over the values of the attribute of the entry being
         * visited (to_visit) and follow them, calling this function
         * recursively.
         * If the value is in the visited array, skip it.
         * Otherwise, follow the link and visit it.
         */
        for (i=0; i<el->num_values; i++) {
                struct dsdb_dn *next_to_visit;
                bool skip = false;

                next_to_visit = dsdb_dn_parse(tmp_ctx, ldb, &el->values[i], dn_oid);
                if (next_to_visit == NULL) {
                        talloc_free(tmp_ctx);
                        *matched = false;
                        return LDB_ERR_INVALID_DN_SYNTAX;
                }

                /*
                 * If the value is already in the visited array, skip it.
                 * Note the last element of the array is ignored because it is
                 * the current entry DN.
                 */
                for (j=0; j < (*visited_count) - 1; j++) {
                        struct dsdb_dn *visited_dn = (*visited)[j];
                        if (ldb_dn_compare(visited_dn->dn,
                                           next_to_visit->dn) == 0) {
                                skip = true;
                                break;
                        }
                }
                if (skip) {
                        talloc_free(next_to_visit);
                        continue;
                }

                /* If the value is not in the visited array, evaluate it */
                ret = ldb_eval_transitive_filter_helper(tmp_ctx, ldb, attr,
                                                        dn_to_match, dn_oid,
                                                        next_to_visit,
                                                        visited, visited_count,
                                                        matched);
                if (ret != LDB_SUCCESS) {
                        talloc_free(tmp_ctx);
                        return ret;
                }
                if (*matched) {
                        talloc_free(tmp_ctx);
                        return LDB_SUCCESS;
                }
        }

        talloc_free(tmp_ctx);
        *matched = false;
        return LDB_SUCCESS;
}

/*
 * This function parses the linked attribute value to match, whose syntax
 * will be one of the different DN syntaxes, into a ldb_dn struct.
 */
static int ldb_eval_transitive_filter(TALLOC_CTX *mem_ctx,
                                      struct ldb_context *ldb,
                                      const char *attr,
                                      const struct ldb_val *value_to_match,
                                      struct dsdb_dn *current_object_dn,
                                      bool *matched)
{
        const struct dsdb_schema *schema;
        const struct dsdb_attribute *schema_attr;
        struct dsdb_dn *dn_to_match;
        const char *dn_oid;
        unsigned int count;
        struct dsdb_dn **visited = NULL;

        schema = dsdb_get_schema(ldb, mem_ctx);
        if (schema == NULL) {
                return LDB_ERR_OPERATIONS_ERROR;
        }

        schema_attr = dsdb_attribute_by_lDAPDisplayName(schema, attr);
        if (schema_attr == NULL) {
                return LDB_ERR_NO_SUCH_ATTRIBUTE;
        }

        /* This is the DN syntax of the attribute being matched */
        dn_oid = schema_attr->syntax->ldap_oid;

        /*
         * Build a ldb_dn struct holding the value to match, which is the
         * value entered in the search filter
         */
        dn_to_match = dsdb_dn_parse(mem_ctx, ldb, value_to_match, dn_oid);
        if (dn_to_match == NULL) {
                *matched = false;
                return LDB_SUCCESS;
        }

        return ldb_eval_transitive_filter_helper(mem_ctx, ldb, attr,
                                                 dn_to_match, dn_oid,
                                                 current_object_dn,
                                                 &visited, &count, matched);
}

/*
 * This rule provides recursive search of a link attribute
 *
 * Documented in [MS-ADTS] section 3.1.1.3.4.4.3 LDAP_MATCHING_RULE_TRANSITIVE_EVAL
 * This allows a search filter such as:
 *
 * member:1.2.840.113556.1.4.1941:=cn=user,cn=users,dc=samba,dc=example,dc=com
 *
 * This searches not only the member attribute, but also any member
 * attributes that point at an object with this member in them.  All the
 * various DN syntax types are supported, not just plain DNs.
 *
 */
static int ldb_comparator_trans(struct ldb_context *ldb,
                                const char *oid,
                                const struct ldb_message *msg,
                                const char *attribute_to_match,
                                const struct ldb_val *value_to_match,
                                bool *matched)
{
        const struct dsdb_schema *schema;
        const struct dsdb_attribute *schema_attr;
        struct ldb_dn *msg_dn;
        struct dsdb_dn *dsdb_msg_dn;
        TALLOC_CTX *tmp_ctx;
        int ret;

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

        /*
         * If the target attribute to match is not a linked attribute, then
         * the filter evaluates to undefined
         */
        schema = dsdb_get_schema(ldb, tmp_ctx);
        if (schema == NULL) {
                talloc_free(tmp_ctx);
                return LDB_ERR_OPERATIONS_ERROR;
        }

        schema_attr = dsdb_attribute_by_lDAPDisplayName(schema, attribute_to_match);
        if (schema_attr == NULL) {
                talloc_free(tmp_ctx);
                return LDB_ERR_NO_SUCH_ATTRIBUTE;
        }

        /*
         * This extended match filter is only valid for linked attributes,
         * following the MS definition (the schema attribute has a linkID
         * defined). See dochelp request 114111212024789 on cifs-protocols
         * mailing list.
         */
        if (schema_attr->linkID == 0) {
                *matched = false;
                talloc_free(tmp_ctx);
                return LDB_SUCCESS;
        }

        /* Duplicate original msg dn as the msg must not be modified */
        msg_dn = ldb_dn_copy(tmp_ctx, msg->dn);
        if (msg_dn == NULL) {
                talloc_free(tmp_ctx);
                return LDB_ERR_OPERATIONS_ERROR;
        }

        /*
         * Build a dsdb dn from the message copied DN, which should be a plain
         * DN syntax.
         */
        dsdb_msg_dn = dsdb_dn_construct(tmp_ctx, msg_dn, data_blob_null,
                                        LDB_SYNTAX_DN);
        if (dsdb_msg_dn == NULL) {
                *matched = false;
                return LDB_ERR_INVALID_DN_SYNTAX;
        }

        ret = ldb_eval_transitive_filter(tmp_ctx, ldb,
                                         attribute_to_match,
                                         value_to_match,
                                         dsdb_msg_dn, matched);
        talloc_free(tmp_ctx);
        return ret;
}


/*
 * This rule provides match of a dns object with expired records.
 *
 * This allows a search filter such as:
 *
 * dnsRecord:1.3.6.1.4.1.7165.4.5.3:=131139216000000000
 *
 * This allows the caller to find records that should become a DNS
 * tomestone, despite that information being deep within an NDR packed
 * object
 */
static int dsdb_match_for_dns_to_tombstone_time(struct ldb_context *ldb,
                                                const char *oid,
                                                const struct ldb_message *msg,
                                                const char *attribute_to_match,
                                                const struct ldb_val *value_to_match,
                                                bool *matched)
{
        TALLOC_CTX *tmp_ctx;
        unsigned int i;
        struct ldb_message_element *el = NULL;
        struct auth_session_info *session_info = NULL;
        uint64_t tombstone_time;
        struct dnsp_DnssrvRpcRecord *rec = NULL;
        enum ndr_err_code err;
        *matched = false;

        /* Needs to be dnsRecord, no match otherwise */
        if (ldb_attr_cmp(attribute_to_match, "dnsRecord") != 0) {
                return LDB_SUCCESS;
        }

        el = ldb_msg_find_element(msg, attribute_to_match);
        if (el == NULL) {
                return LDB_SUCCESS;
        }

        session_info = talloc_get_type(ldb_get_opaque(ldb, "sessionInfo"),
                                       struct auth_session_info);
        if (session_info == NULL) {
                return ldb_oom(ldb);
        }
        if (security_session_user_level(session_info, NULL)
                != SECURITY_SYSTEM) {

                DBG_ERR("unauthorised access\n");
                return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
        }

        /* Just check we don't allow the caller to fill our stack */
        if (value_to_match->length >= 64) {
                DBG_ERR("Invalid timestamp passed\n");
                return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
        } else {
                char *p = NULL;
                char s[value_to_match->length+1];
                memcpy(s, value_to_match->data, value_to_match->length);
                s[value_to_match->length] = 0;
                if (s[0] == '\0' || s[0] == '-') {
                        DBG_ERR("Empty timestamp passed\n");
                        return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
                }
                tombstone_time = strtoull(s, &p, 10);
                if (p == NULL || p == s || *p != '\0' ||
                    tombstone_time == ULLONG_MAX) {
                        DBG_ERR("Invalid timestamp string passed\n");
                        return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
                }
        }

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

        for (i = 0; i < el->num_values; i++) {
                rec = talloc_zero(tmp_ctx, struct dnsp_DnssrvRpcRecord);
                if (rec == NULL) {
                        TALLOC_FREE(tmp_ctx);
                        return ldb_oom(ldb);
                }
                err = ndr_pull_struct_blob(
                        &(el->values[i]),
                        tmp_ctx,
                        rec,
                        (ndr_pull_flags_fn_t)ndr_pull_dnsp_DnssrvRpcRecord);
                if (!NDR_ERR_CODE_IS_SUCCESS(err)){
                        DBG_ERR("Failed to pull dns rec blob.\n");
                        TALLOC_FREE(tmp_ctx);
                        return LDB_ERR_OPERATIONS_ERROR;
                }

                if (rec->wType == DNS_TYPE_SOA || rec->wType == DNS_TYPE_NS) {
                        TALLOC_FREE(tmp_ctx);
                        continue;
                }

                if (rec->wType == DNS_TYPE_TOMBSTONE) {
                        TALLOC_FREE(tmp_ctx);
                        continue;
                }
                if (rec->dwTimeStamp == 0) {
                        TALLOC_FREE(tmp_ctx);
                        continue;
                }
                if (rec->dwTimeStamp > tombstone_time) {
                        TALLOC_FREE(tmp_ctx);
                        continue;
                }

                *matched = true;
                break;
        }

        TALLOC_FREE(tmp_ctx);
        return LDB_SUCCESS;
}


/*
 * This rule provides match of a link attribute against a 'should be expunged' criteria
 *
 * This allows a search filter such as:
 *
 * member:1.3.6.1.4.1.7165.4.5.2:=131139216000000000
 *
 * This searches the member attribute, but also any member attributes
 * that are deleted and should be expunged after the specified NTTIME
 * time.
 *
 */
static int dsdb_match_for_expunge(struct ldb_context *ldb,
                                  const char *oid,
                                  const struct ldb_message *msg,
                                  const char *attribute_to_match,
                                  const struct ldb_val *value_to_match,
                                  bool *matched)
{
        const struct dsdb_schema *schema;
        const struct dsdb_attribute *schema_attr;
        TALLOC_CTX *tmp_ctx;
        unsigned int i;
        struct ldb_message_element *el;
        struct auth_session_info *session_info;
        uint64_t tombstone_time;
        *matched = false;

        el = ldb_msg_find_element(msg, attribute_to_match);
        if (el == NULL) {
                return LDB_SUCCESS;
        }

        session_info
                = talloc_get_type(ldb_get_opaque(ldb, DSDB_SESSION_INFO),
                                  struct auth_session_info);
        if (security_session_user_level(session_info, NULL) != SECURITY_SYSTEM) {
                return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
        }

        /*
         * If the target attribute to match is not a linked attribute, then
         * the filter evaluates to undefined
         */
        schema = dsdb_get_schema(ldb, NULL);
        if (schema == NULL) {
                return LDB_ERR_OPERATIONS_ERROR;
        }

        /* TODO this is O(log n) per attribute */
        schema_attr = dsdb_attribute_by_lDAPDisplayName(schema, attribute_to_match);
        if (schema_attr == NULL) {
                return LDB_ERR_NO_SUCH_ATTRIBUTE;
        }

        /*
         * This extended match filter is only valid for forward linked attributes.
         */
        if (schema_attr->linkID == 0 || (schema_attr->linkID & 1) == 1) {
                return LDB_ERR_NO_SUCH_ATTRIBUTE;
        }

        /* Just check we don't allow the caller to fill our stack */
        if (value_to_match->length >=64) {
                return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
        } else {
                char *p = NULL;
                char s[value_to_match->length+1];
                memcpy(s, value_to_match->data, value_to_match->length);
                s[value_to_match->length] = 0;
                if (s[0] == '\0' || s[0] == '-') {
                        return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
                }
                tombstone_time = strtoull(s, &p, 10);
                if (p == NULL || p == s || *p != '\0' || tombstone_time == ULLONG_MAX) {
                        return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
                }
        }

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

        for (i = 0; i < el->num_values; i++) {
                NTSTATUS status;
                struct dsdb_dn *dn;
                uint64_t rmd_changetime;
                if (dsdb_dn_is_deleted_val(&el->values[i]) == false) {
                        continue;
                }

                dn = dsdb_dn_parse(tmp_ctx, ldb, &el->values[i],
                                   schema_attr->syntax->ldap_oid);
                if (dn == NULL) {
                        DEBUG(1, ("Error: Failed to parse linked attribute blob of %s.\n", el->name));
                        continue;
                }

                status = dsdb_get_extended_dn_uint64(dn->dn, &rmd_changetime,
                                                     "RMD_CHANGETIME");
                if (!NT_STATUS_IS_OK(status)) {
                        DEBUG(1, ("Error: RMD_CHANGETIME is missing on a forward link.\n"));
                        continue;
                }

                if (rmd_changetime > tombstone_time) {
                        continue;
                }

                *matched = true;
                break;
        }
        talloc_free(tmp_ctx);
        return LDB_SUCCESS;
}


int ldb_register_samba_matching_rules(struct ldb_context *ldb)
{
        struct ldb_extended_match_rule *transitive_eval = NULL,
                *match_for_expunge = NULL,
                *match_for_dns_to_tombstone_time = NULL;
        int ret;

        transitive_eval = talloc_zero(ldb, struct ldb_extended_match_rule);
        transitive_eval->oid = SAMBA_LDAP_MATCH_RULE_TRANSITIVE_EVAL;
        transitive_eval->callback = ldb_comparator_trans;
        ret = ldb_register_extended_match_rule(ldb, transitive_eval);
        if (ret != LDB_SUCCESS) {
                talloc_free(transitive_eval);
                return ret;
        }

        match_for_expunge = talloc_zero(ldb, struct ldb_extended_match_rule);
        match_for_expunge->oid = DSDB_MATCH_FOR_EXPUNGE;
        match_for_expunge->callback = dsdb_match_for_expunge;
        ret = ldb_register_extended_match_rule(ldb, match_for_expunge);
        if (ret != LDB_SUCCESS) {
                talloc_free(match_for_expunge);
                return ret;
        }

        match_for_dns_to_tombstone_time = talloc_zero(
                ldb,
                struct ldb_extended_match_rule);
        match_for_dns_to_tombstone_time->oid = DSDB_MATCH_FOR_DNS_TO_TOMBSTONE_TIME;
        match_for_dns_to_tombstone_time->callback
                = dsdb_match_for_dns_to_tombstone_time;
        ret = ldb_register_extended_match_rule(ldb,
                                               match_for_dns_to_tombstone_time);
        if (ret != LDB_SUCCESS) {
                TALLOC_FREE(match_for_dns_to_tombstone_time);
                return ret;
        }

        return LDB_SUCCESS;
}