autorid: reserve 500 IDs at the top of the ALLOC range.

[Samba/wip.git] / source3 / winbindd / idmap_autorid.c

/*
 *  idmap_autorid: static map between Active Directory/NT RIDs
 *  and RFC 2307 accounts
 *
 *  based on the idmap_rid module, but this module defines the ranges
 *  for the domains by automatically allocating a range for each domain
 *
 *  Copyright (C) Christian Ambach, 2010-2012
 *
 *  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/>.
 *
 */

/*
 * This module allocates ranges for domains to be used in a
 * algorithmic mode like idmap_rid. Multiple ranges are supported
 * for a single domain: If a rid exceeds the range size, a matching
 * range is allocated to hold the rid's id.
 *
 * Here are the formulas applied:
 *
 *
 * For a sid of the form domain_sid-rid, we have
 *
 *   rid = reduced_rid + domain_range_index * range_size
 *
 * with
 *   reduced_rid := rid % range_size
 *   domain_range_index := rid / range_size
 *
 * And reduced_rid fits into a range.
 *
 * In the database, we associate a range_number to
 * the pair domain_sid,domain_range_index.
 *
 * Now the unix id for the given sid calculates as:
 *
 *   id = reduced_rid + range_low_id
 *
 * with
 *
 *   range_low_id = low_id + range_number * range_size
 *
 *
 * The inverse calculation goes like this:
 *
 * Given a unix id, let
 *
 *   normalized_id := id - low_id
 *   reduced_rid := normalized_id % range_size
 *   range_number = normalized_id / range_size
 *
 * Then we have
 *
 *   id = reduced_rid + low_id + range_number * range_size
 *
 * From the database, get the domain_sid,domain_range_index pair
 * belonging to the range_number (if there is already one).
 *
 * Then the rid for the unix id calculates as:
 *
 *   rid = reduced_rid + domain_range_index * range_size
 */

#include "idmap_autorid_tdb.h"
#include "winbindd.h"
#include "idmap.h"
#include "idmap_rw.h"
#include "../libcli/security/dom_sid.h"

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_IDMAP

#define IDMAP_AUTORID_ALLOC_RESERVED 500

/* handle to the tdb storing domain <-> range assignments */
static struct db_context *autorid_db;

static bool ignore_builtin = false;

static NTSTATUS idmap_autorid_get_alloc_range(struct idmap_domain *dom,
                                        struct autorid_range_config *range)
{
        NTSTATUS status;

        ZERO_STRUCT(*range);

        fstrcpy(range->domsid, ALLOC_RANGE);

        status = idmap_autorid_get_domainrange(autorid_db,
                                               range,
                                               dom->read_only);

        return status;
}

static NTSTATUS idmap_autorid_allocate_id(struct idmap_domain *dom,
                                          struct unixid *xid) {

        NTSTATUS ret;
        struct autorid_range_config range;

        if (dom->read_only) {
                DEBUG(3, ("Backend is read-only, refusing "
                          "new allocation request\n"));
                return NT_STATUS_UNSUCCESSFUL;
        }

        /* fetch the range for the allocation pool */

        ret = idmap_autorid_get_alloc_range(dom, &range);
        if (!NT_STATUS_IS_OK(ret)) {
                DEBUG(3, ("Could not determine range for allocation pool, "
                          "check previous messages for reason\n"));
                return ret;
        }

        ret = idmap_tdb_common_get_new_id(dom, xid);

        if (!NT_STATUS_IS_OK(ret)) {
                DEBUG(1, ("Fatal error while allocating new ID!\n"));
                return ret;
        }

        xid->id = xid->id + range.low_id;

        DEBUG(10, ("Returned new %s %d from allocation range\n",
                   (xid->type==ID_TYPE_UID)?"uid":"gid", xid->id));

        return ret;
}

/*
 * map a SID to xid using the idmap_tdb like pool
 */
static NTSTATUS idmap_autorid_id_to_sid_alloc(struct idmap_domain *dom,
                                              struct id_map *map)
{
        NTSTATUS ret;

        /* look out for the mapping */
        ret = idmap_tdb_common_unixid_to_sid(dom, map);

        if (NT_STATUS_IS_OK(ret)) {
                map->status = ID_MAPPED;
                return ret;
        }

        map->status = ID_UNKNOWN;

        DEBUG(10, ("no ID->SID mapping for %d could be found\n", map->xid.id));

        return ret;
}

static NTSTATUS idmap_autorid_id_to_sid(struct autorid_global_config *cfg,
                                        struct idmap_domain *dom,
                                        struct id_map *map)
{
        uint32_t range_number;
        uint32_t domain_range_index = 0;
        uint32_t normalized_id;
        uint32_t reduced_rid;
        uint32_t rid;
        TDB_DATA data = tdb_null;
        char *keystr;
        struct dom_sid domsid;
        NTSTATUS status;
        bool ok;
        const char *q = NULL;

        /* can this be one of our ids? */
        if (map->xid.id < cfg->minvalue) {
                DEBUG(10, ("id %d is lower than minimum value, "
                           "ignoring mapping request\n", map->xid.id));
                map->status = ID_UNKNOWN;
                return NT_STATUS_OK;
        }

        if (map->xid.id > (cfg->minvalue + cfg->rangesize * cfg->maxranges)) {
                DEBUG(10, ("id %d is outside of maximum id value, "
                           "ignoring mapping request\n", map->xid.id));
                map->status = ID_UNKNOWN;
                return NT_STATUS_OK;
        }

        /* determine the range of this uid */

        normalized_id = map->xid.id - cfg->minvalue;
        range_number = normalized_id / cfg->rangesize;

        keystr = talloc_asprintf(talloc_tos(), "%u", range_number);
        if (!keystr) {
                return NT_STATUS_NO_MEMORY;
        }

        status = dbwrap_fetch_bystring(autorid_db, talloc_tos(), keystr, &data);
        TALLOC_FREE(keystr);

        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(4, ("id %d belongs to range %d which does not have "
                          "domain mapping, ignoring mapping request\n",
                          map->xid.id, range_number));
                TALLOC_FREE(data.dptr);
                map->status = ID_UNKNOWN;
                return NT_STATUS_OK;
        }

        if (strncmp((const char *)data.dptr,
                    ALLOC_RANGE,
                    strlen(ALLOC_RANGE)) == 0) {
                /*
                 * this is from the alloc range, check if there is a mapping
                 */
                DEBUG(5, ("id %d belongs to allocation range, "
                          "checking for mapping\n",
                          map->xid.id));
                TALLOC_FREE(data.dptr);
                return idmap_autorid_id_to_sid_alloc(dom, map);
        }

        ok = dom_sid_parse_endp((const char *)data.dptr, &domsid, &q);
        TALLOC_FREE(data.dptr);
        if (!ok) {
                map->status = ID_UNKNOWN;
                return NT_STATUS_OK;
        }
        if ((q != NULL) && (*q != '\0'))
                if (sscanf(q+1, "%"SCNu32, &domain_range_index) != 1) {
                        DEBUG(10, ("Domain range index not found, "
                                   "ignoring mapping request\n"));
                        map->status = ID_UNKNOWN;
                        return NT_STATUS_OK;
                }

        reduced_rid = normalized_id % cfg->rangesize;
        rid = reduced_rid + domain_range_index * cfg->rangesize;

        sid_compose(map->sid, &domsid, rid);

        /* We **really** should have some way of validating
           the SID exists and is the correct type here.  But
           that is a deficiency in the idmap_rid design. */

        map->status = ID_MAPPED;
        map->xid.type = ID_TYPE_BOTH;

        return NT_STATUS_OK;
}

/**********************************
 Single sid to id lookup function.
**********************************/

static NTSTATUS idmap_autorid_sid_to_id_rid(
                                        struct autorid_global_config *global,
                                        struct autorid_range_config *range,
                                        struct id_map *map)
{
        uint32_t rid;
        uint32_t reduced_rid;

        sid_peek_rid(map->sid, &rid);

        reduced_rid = rid % global->rangesize;

        map->xid.id = reduced_rid + range->low_id;
        map->xid.type = ID_TYPE_BOTH;
        map->status = ID_MAPPED;

        return NT_STATUS_OK;
}

/**********************************
 lookup a set of unix ids.
**********************************/

static NTSTATUS idmap_autorid_unixids_to_sids(struct idmap_domain *dom,
                                              struct id_map **ids)
{
        struct idmap_tdb_common_context *commoncfg;
        struct autorid_global_config *globalcfg;
        NTSTATUS ret;
        int i;
        int num_tomap = 0;
        int num_mapped = 0;

        /* initialize the status to avoid surprise */
        for (i = 0; ids[i]; i++) {
                ids[i]->status = ID_UNKNOWN;
                num_tomap++;
        }

        commoncfg =
            talloc_get_type_abort(dom->private_data,
                                  struct idmap_tdb_common_context);

        globalcfg = talloc_get_type(commoncfg->private_data,
                                    struct autorid_global_config);

        for (i = 0; ids[i]; i++) {

                ret = idmap_autorid_id_to_sid(globalcfg, dom, ids[i]);

                if ((!NT_STATUS_IS_OK(ret)) &&
                    (!NT_STATUS_EQUAL(ret, NT_STATUS_NONE_MAPPED))) {
                        /* some fatal error occurred, log it */
                        DEBUG(3, ("Unexpected error resolving an ID "
                                  " (%d)\n", ids[i]->xid.id));
                        goto failure;
                }

                if (NT_STATUS_IS_OK(ret) && ids[i]->status == ID_MAPPED) {
                        num_mapped++;
                }

        }

        if (num_tomap == num_mapped) {
                return NT_STATUS_OK;
        } else if (num_mapped == 0) {
                return NT_STATUS_NONE_MAPPED;
        }

        return STATUS_SOME_UNMAPPED;


      failure:
        return ret;
}

/*
 * map a SID to xid using the idmap_tdb like pool
 */
static NTSTATUS idmap_autorid_sid_to_id_alloc(
                                        struct idmap_tdb_common_context *ctx,
                                        struct idmap_domain *dom,
                                        struct id_map *map)
{
        NTSTATUS ret;
        int res;

        map->status = ID_UNKNOWN;

        /* see if we already have a mapping */
        ret = idmap_tdb_common_sid_to_unixid(dom, map);

        if (NT_STATUS_IS_OK(ret)) {
                map->status = ID_MAPPED;
                return ret;
        }

        /* bad things happened */
        if (!NT_STATUS_EQUAL(ret, NT_STATUS_NONE_MAPPED)) {
                DEBUG(1, ("Looking up SID->ID mapping for %s failed: %s\n",
                          sid_string_dbg(map->sid), nt_errstr(ret)));
                return ret;
        }

        if (dom->read_only) {
                DEBUG(3, ("Not allocating new mapping for %s, because backend "
                          "is read-only\n", sid_string_dbg(map->sid)));
                map->status = ID_UNMAPPED;
                return NT_STATUS_NONE_MAPPED;
        }

        DEBUG(10, ("Creating new mapping in pool for %s\n",
                   sid_string_dbg(map->sid)));

        /* create new mapping */
        res = dbwrap_transaction_start(ctx->db);
        if (res != 0) {
                DEBUG(2, ("transaction_start failed\n"));
                return NT_STATUS_INTERNAL_DB_CORRUPTION;
        }

        ret = idmap_tdb_common_new_mapping(dom, map);
        if (!NT_STATUS_IS_OK(ret)) {
                if (dbwrap_transaction_cancel(ctx->db) != 0) {
                        smb_panic("Cancelling transaction failed");
                }
                map->status = ID_UNMAPPED;
                return ret;
        }

        res = dbwrap_transaction_commit(ctx->db);
        if (res == 0) {
                map->status = ID_MAPPED;
                return NT_STATUS_OK;
        }

        DEBUG(2, ("transaction_commit failed\n"));
        return NT_STATUS_INTERNAL_DB_CORRUPTION;

}

static bool idmap_autorid_domsid_is_for_alloc(struct dom_sid *sid)
{
        bool match;

        match = sid_check_is_wellknown_domain(sid, NULL);
        if (match) {
                return true;
        }

        return false;
}

static NTSTATUS idmap_autorid_sid_to_id(struct idmap_tdb_common_context *common,
                                        struct idmap_domain *dom,
                                        struct id_map *map)
{
        struct autorid_global_config *global =
                talloc_get_type_abort(common->private_data,
                                      struct autorid_global_config);
        struct winbindd_tdc_domain *domain;
        struct autorid_range_config range;
        uint32_t rid;
        struct dom_sid domainsid;
        NTSTATUS ret;

        ZERO_STRUCT(range);
        map->status = ID_UNKNOWN;

        DEBUG(10, ("Trying to map %s\n", sid_string_dbg(map->sid)));

        sid_copy(&domainsid, map->sid);
        if (!sid_split_rid(&domainsid, &rid)) {
                DEBUG(4, ("Could not determine domain SID from %s, "
                          "ignoring mapping request\n",
                          sid_string_dbg(map->sid)));
                map->status = ID_UNMAPPED;
                return NT_STATUS_NONE_MAPPED;
        }

        if (idmap_autorid_domsid_is_for_alloc(&domainsid)) {
                DEBUG(10, ("SID %s is for ALLOC range.\n",
                           sid_string_dbg(map->sid)));

                return idmap_autorid_sid_to_id_alloc(common, dom, map);
        }

        if (dom_sid_equal(&domainsid, &global_sid_Builtin) && ignore_builtin) {
                DEBUG(10, ("Ignoring request for BUILTIN domain\n"));
                map->status = ID_UNMAPPED;
                return NT_STATUS_NONE_MAPPED;
        }

        /*
         * Check if the domain is around
         */
        domain = wcache_tdc_fetch_domainbysid(talloc_tos(),
                                              &domainsid);
        if (domain == NULL) {
                DEBUG(10, ("Ignoring unknown domain sid %s\n",
                           sid_string_dbg(&domainsid)));
                map->status = ID_UNMAPPED;
                return NT_STATUS_NONE_MAPPED;
        }
        TALLOC_FREE(domain);

        sid_to_fstring(range.domsid, &domainsid);

        range.domain_range_index = rid / (global->rangesize);

        ret = idmap_autorid_get_domainrange(autorid_db, &range, dom->read_only);
        if (NT_STATUS_EQUAL(ret, NT_STATUS_NOT_FOUND) && dom->read_only) {
                DEBUG(10, ("read-only is enabled, did not allocate "
                           "new range for domain %s\n",
                           sid_string_dbg(&domainsid)));
                map->status = ID_UNMAPPED;
                return NT_STATUS_NONE_MAPPED;
        }
        if (!NT_STATUS_IS_OK(ret)) {
                DEBUG(3, ("Could not determine range for domain, "
                          "check previous messages for reason\n"));
                return ret;
        }

        return idmap_autorid_sid_to_id_rid(global, &range, map);
}

/**********************************
 lookup a set of sids.
**********************************/

static NTSTATUS idmap_autorid_sids_to_unixids(struct idmap_domain *dom,
                                              struct id_map **ids)
{
        struct idmap_tdb_common_context *commoncfg;
        NTSTATUS ret;
        int i;
        int num_tomap = 0;
        int num_mapped = 0;

        /* initialize the status to avoid surprise */
        for (i = 0; ids[i]; i++) {
                ids[i]->status = ID_UNKNOWN;
                num_tomap++;
        }

        commoncfg =
            talloc_get_type_abort(dom->private_data,
                                  struct idmap_tdb_common_context);

        for (i = 0; ids[i]; i++) {
                ret = idmap_autorid_sid_to_id(commoncfg, dom, ids[i]);
                if ((!NT_STATUS_IS_OK(ret)) &&
                    (!NT_STATUS_EQUAL(ret, NT_STATUS_NONE_MAPPED))) {
                        /* some fatal error occurred, log it */
                        DEBUG(3, ("Unexpected error resolving a SID (%s)\n",
                                  sid_string_dbg(ids[i]->sid)));
                        return ret;
                }

                if (NT_STATUS_IS_OK(ret) && ids[i]->status == ID_MAPPED) {
                        num_mapped++;
                }
        }

        if (num_tomap == num_mapped) {
                return NT_STATUS_OK;
        } else if (num_mapped == 0) {
                return NT_STATUS_NONE_MAPPED;
        }

        return STATUS_SOME_UNMAPPED;
}

static NTSTATUS idmap_autorid_preallocate_wellknown(struct idmap_domain *dom)
{
        const char *groups[] = { "S-1-1-0", "S-1-2-0", "S-1-2-1",
                "S-1-3-0", "S-1-3-1", "S-1-3-2", "S-1-3-3", "S-1-3-4",
                "S-1-5-1", "S-1-5-2", "S-1-5-3", "S-1-5-4", "S-1-5-6",
                "S-1-5-7", "S-1-5-8", "S-1-5-9", "S-1-5-10", "S-1-5-11",
                "S-1-5-12", "S-1-5-13", "S-1-5-14", "S-1-5-15",
                "S-1-5-17", "S-1-5-18", "S-1-5-19", "S-1-5-20"
        };

        struct id_map **maps;
        int i, num;
        NTSTATUS status;

        if (dom->read_only) {
                return NT_STATUS_OK;
        }

        num = ARRAY_SIZE(groups);

        maps = talloc_array(talloc_tos(), struct id_map*, num+1);
        if (!maps) {
                return NT_STATUS_NO_MEMORY;
        }

        for (i = 0; i < num; i++) {
                maps[i] = talloc(maps, struct id_map);
                if (maps[i] == NULL) {
                        talloc_free(maps);
                        return NT_STATUS_NO_MEMORY;
                }
                maps[i]->xid.type = ID_TYPE_GID;
                maps[i]->sid = dom_sid_parse_talloc(maps, groups[i]);
        }

        maps[num] = NULL;

        status = idmap_autorid_sids_to_unixids(dom, maps);

        DEBUG(10,("Preallocation run finished with status %s\n",
                  nt_errstr(status)));

        talloc_free(maps);

        return NT_STATUS_IS_OK(status)?NT_STATUS_OK:NT_STATUS_UNSUCCESSFUL;
}

static NTSTATUS idmap_autorid_initialize_action(struct db_context *db,
                                                void *private_data)
{
        struct idmap_domain *dom;
        struct idmap_tdb_common_context *common;
        struct autorid_global_config *config;
        NTSTATUS status;

        dom = (struct idmap_domain *)private_data;
        common = (struct idmap_tdb_common_context *)dom->private_data;
        config = (struct autorid_global_config *)common->private_data;

        status = idmap_autorid_init_hwms(db);
        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }

        status = idmap_autorid_saveconfig(db, config);
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(1, ("Failed to store configuration data!\n"));
                return status;
        }

        status = idmap_autorid_preallocate_wellknown(dom);
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(1, ("Failed to preallocate wellknown sids: %s\n",
                          nt_errstr(status)));
                return status;
        }

        return NT_STATUS_OK;
}

static NTSTATUS idmap_autorid_initialize(struct idmap_domain *dom)
{
        struct idmap_tdb_common_context *commonconfig;
        struct autorid_global_config *config;
        NTSTATUS status;

        if (!strequal(dom->name, "*")) {
                DEBUG(0, ("idmap_autorid_initialize: Error: autorid configured "
                          "for domain '%s'. But autorid can only be used for "
                          "the default idmap configuration.\n", dom->name));
                return NT_STATUS_INVALID_PARAMETER;
        }

        commonconfig = talloc_zero(dom, struct idmap_tdb_common_context);
        if (!commonconfig) {
                DEBUG(0, ("Out of memory!\n"));
                return NT_STATUS_NO_MEMORY;
        }
        dom->private_data = commonconfig;

        commonconfig->rw_ops = talloc_zero(commonconfig, struct idmap_rw_ops);
        if (commonconfig->rw_ops == NULL) {
                DEBUG(0, ("Out of memory!\n"));
                return NT_STATUS_NO_MEMORY;
        }

        config = talloc_zero(commonconfig, struct autorid_global_config);
        if (!config) {
                DEBUG(0, ("Out of memory!\n"));
                return NT_STATUS_NO_MEMORY;
        }
        commonconfig->private_data = config;

        config->minvalue = dom->low_id;
        config->rangesize = lp_parm_int(-1, "idmap config *",
                                        "rangesize", 100000);

        config->maxranges = (dom->high_id - dom->low_id + 1) /
            config->rangesize;

        if (config->maxranges == 0) {
                DEBUG(1, ("Allowed uid range is smaller than rangesize. "
                          "Increase uid range or decrease rangesize.\n"));
                status = NT_STATUS_INVALID_PARAMETER;
                goto error;
        }

        /* check if the high-low limit is a multiple of the rangesize */
        if ((dom->high_id - dom->low_id + 1) % config->rangesize != 0) {
                DEBUG(5, ("High uid-low uid difference of %d "
                          "is not a multiple of the rangesize %d, "
                          "limiting ranges to lower boundary number of %d\n",
                          (dom->high_id - dom->low_id + 1), config->rangesize,
                          config->maxranges));
        }

        DEBUG(5, ("%d domain ranges with a size of %d are available\n",
                  config->maxranges, config->rangesize));

        ignore_builtin = lp_parm_bool(-1, "idmap config *",
                                      "ignore builtin", false);

        /* fill the TDB common configuration */

        commonconfig->max_id = config->rangesize - 1
                             - IDMAP_AUTORID_ALLOC_RESERVED;
        commonconfig->hwmkey_uid = ALLOC_HWM_UID;
        commonconfig->hwmkey_gid = ALLOC_HWM_GID;
        commonconfig->rw_ops->get_new_id = idmap_autorid_allocate_id;
        commonconfig->rw_ops->set_mapping = idmap_tdb_common_set_mapping;

        status = idmap_autorid_db_open(state_path("autorid.tdb"),
                                       NULL, /* TALLOC_CTX */
                                       &autorid_db);
        if (!NT_STATUS_IS_OK(status)) {
                goto error;
        }

        commonconfig->db = autorid_db;

        status = dbwrap_trans_do(autorid_db,
                                 idmap_autorid_initialize_action,
                                 dom);
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(1, ("Failed to init the idmap database: %s\n",
                          nt_errstr(status)));
                goto error;
        }

        goto done;

error:
        talloc_free(config);

done:
        return status;
}

/*
  Close the idmap tdb instance
*/
static struct idmap_methods autorid_methods = {
        .init = idmap_autorid_initialize,
        .unixids_to_sids = idmap_autorid_unixids_to_sids,
        .sids_to_unixids = idmap_autorid_sids_to_unixids,
        .allocate_id     = idmap_autorid_allocate_id
};

NTSTATUS idmap_autorid_init(void)
{
        return smb_register_idmap(SMB_IDMAP_INTERFACE_VERSION,
                                  "autorid", &autorid_methods);
}