source: vendor/3.6.23/source4/param/secrets.c

/* 
   Unix SMB/CIFS implementation.
   Copyright (C) Andrew Tridgell 1992-2001
   Copyright (C) Andrew Bartlett      2002
   Copyright (C) Rafal Szczesniak     2002
   
   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/>.
*/

/* the Samba secrets database stores any generated, private information
   such as the local SID and machine trust password */

#include "includes.h"
#include "secrets.h"
#include "param/param.h"
#include "system/filesys.h"
#include "lib/util/tdb_wrap.h"
#include "lib/ldb-samba/ldb_wrap.h"
#include <ldb.h>
#include "../lib/util/util_tdb.h"
#include "librpc/gen_ndr/ndr_security.h"
#include "dsdb/samdb/samdb.h"

/**
 * Use a TDB to store an incrementing random seed.
 *
 * Initialised to the current pid, the very first time Samba starts,
 * and incremented by one each time it is needed.  
 * 
 * @note Not called by systems with a working /dev/urandom.
 */
static void get_rand_seed(struct tdb_wrap *secretsdb, int *new_seed) 
{
        *new_seed = getpid();
        if (secretsdb != NULL) {
                tdb_change_int32_atomic(secretsdb->tdb, "INFO/random_seed", new_seed, 1);
        }
}

/**
 * open up the secrets database
 */
struct tdb_wrap *secrets_init(TALLOC_CTX *mem_ctx, struct loadparm_context *lp_ctx)
{
        char *fname;
        uint8_t dummy;
        struct tdb_wrap *tdb;

        fname = private_path(mem_ctx, lp_ctx, "secrets.tdb");

        tdb = tdb_wrap_open(mem_ctx, fname, 0, TDB_DEFAULT, O_RDWR|O_CREAT, 0600);

        if (!tdb) {
                DEBUG(0,("Failed to open %s\n", fname));
                talloc_free(fname);
                return NULL;
        }
        talloc_free(fname);

        /**
         * Set a reseed function for the crypto random generator 
         * 
         * This avoids a problem where systems without /dev/urandom
         * could send the same challenge to multiple clients
         */
        set_rand_reseed_callback((void (*) (void *, int *))get_rand_seed, tdb);

        /* Ensure that the reseed is done now, while we are root, etc */
        generate_random_buffer(&dummy, sizeof(dummy));

        return tdb;
}

/**
  connect to the secrets ldb
*/
struct ldb_context *secrets_db_connect(TALLOC_CTX *mem_ctx,
                                        struct loadparm_context *lp_ctx)
{
        return ldb_wrap_connect(mem_ctx, NULL, lp_ctx, lpcfg_secrets_url(lp_ctx),
                               NULL, NULL, 0);
}

/**
 * Retrieve the domain SID from the secrets database.
 * @return pointer to a SID object if the SID could be obtained, NULL otherwise
 */
struct dom_sid *secrets_get_domain_sid(TALLOC_CTX *mem_ctx,
                                       struct loadparm_context *lp_ctx,
                                       const char *domain,
                                       enum netr_SchannelType *sec_channel_type,
                                       char **errstring)
{
        struct ldb_context *ldb;
        struct ldb_message *msg;
        int ldb_ret;
        const char *attrs[] = { "objectSid", "secureChannelType", NULL };
        struct dom_sid *result = NULL;
        const struct ldb_val *v;
        enum ndr_err_code ndr_err;

        *errstring = NULL;

        ldb = secrets_db_connect(mem_ctx, lp_ctx);
        if (ldb == NULL) {
                DEBUG(5, ("secrets_db_connect failed\n"));
                return NULL;
        }

        ldb_ret = dsdb_search_one(ldb, ldb, &msg,
                              ldb_dn_new(mem_ctx, ldb, SECRETS_PRIMARY_DOMAIN_DN),
                              LDB_SCOPE_ONELEVEL,
                              attrs, 0, SECRETS_PRIMARY_DOMAIN_FILTER, domain);

        if (ldb_ret != LDB_SUCCESS) {
                *errstring = talloc_asprintf(mem_ctx, "Failed to find record for %s in %s: %s: %s", 
                                             domain, (char *) ldb_get_opaque(ldb, "ldb_url"),
                                             ldb_strerror(ldb_ret), ldb_errstring(ldb));
                return NULL;
        }
        v = ldb_msg_find_ldb_val(msg, "objectSid");
        if (v == NULL) {
                *errstring = talloc_asprintf(mem_ctx, "Failed to find a SID on record for %s in %s", 
                                             domain, (char *) ldb_get_opaque(ldb, "ldb_url"));
                return NULL;
        }

        if (sec_channel_type) {
                int t;
                t = ldb_msg_find_attr_as_int(msg, "secureChannelType", -1);
                if (t == -1) {
                        *errstring = talloc_asprintf(mem_ctx, "Failed to find secureChannelType for %s in %s",
                                                     domain, (char *) ldb_get_opaque(ldb, "ldb_url"));
                        return NULL;
                }
                *sec_channel_type = t;
        }

        result = talloc(mem_ctx, struct dom_sid);
        if (result == NULL) {
                talloc_free(ldb);
                return NULL;
        }

        ndr_err = ndr_pull_struct_blob(v, result, result,
                                       (ndr_pull_flags_fn_t)ndr_pull_dom_sid);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                *errstring = talloc_asprintf(mem_ctx, "Failed to parse SID on record for %s in %s", 
                                             domain, (char *) ldb_get_opaque(ldb, "ldb_url"));
                talloc_free(result);
                talloc_free(ldb);
                return NULL;
        }

        return result;
}

char *keytab_name_from_msg(TALLOC_CTX *mem_ctx, struct ldb_context *ldb, struct ldb_message *msg) 
{
        const char *krb5keytab = ldb_msg_find_attr_as_string(msg, "krb5Keytab", NULL);
        if (krb5keytab) {
                return talloc_strdup(mem_ctx, krb5keytab);
        } else {
                char *file_keytab;
                char *relative_path;
                const char *privateKeytab = ldb_msg_find_attr_as_string(msg, "privateKeytab", NULL);
                if (!privateKeytab) {
                        return NULL;
                }

                relative_path = ldb_relative_path(ldb, mem_ctx, privateKeytab);
                if (!relative_path) {
                        return NULL;
                }
                file_keytab = talloc_asprintf(mem_ctx, "FILE:%s", relative_path);
                talloc_free(relative_path);
                return file_keytab;
        }
        return NULL;
}