source4/param/secrets.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Copyright (C) Andrew Tridgell 1992-2001
   4    Copyright (C) Andrew Bartlett      2002
   5    Copyright (C) Rafal Szczesniak     2002
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 /* the Samba secrets database stores any generated, private information
  22    such as the local SID and machine trust password */
  23
  24 #include "includes.h"
  25 #include "secrets.h"
  26 #include "param/param.h"
  27 #include "system/filesys.h"
  28 #include "tdb_wrap.h"
  29 #include "lib/ldb/include/ldb.h"
  30 #include "../tdb/include/tdb.h"
  31 #include "../lib/util/util_tdb.h"
  32 #include "../lib/util/util_ldb.h"
  33 #include "librpc/gen_ndr/ndr_security.h"
  34 #include "dsdb/samdb/samdb.h"
  35 #include "dsdb/common/util.h"
  36 #include "dsdb/common/proto.h"
  37
  38 /**
  39  * Use a TDB to store an incrementing random seed.
  40  *
  41  * Initialised to the current pid, the very first time Samba starts,
  42  * and incremented by one each time it is needed.
  43  *
  44  * @note Not called by systems with a working /dev/urandom.
  45  */
  46 static void get_rand_seed(struct tdb_wrap *secretsdb, int *new_seed)
  47 {
  48         *new_seed = getpid();
  49         if (secretsdb != NULL) {
  50                 tdb_change_int32_atomic(secretsdb->tdb, "INFO/random_seed", new_seed, 1);
  51         }
  52 }
  53
  54 /**
  55  * open up the secrets database
  56  */
  57 struct tdb_wrap *secrets_init(TALLOC_CTX *mem_ctx, struct loadparm_context *lp_ctx)
  58 {
  59         char *fname;
  60         uint8_t dummy;
  61         struct tdb_wrap *tdb;
  62
  63         fname = private_path(mem_ctx, lp_ctx, "secrets.tdb");
  64
  65         tdb = tdb_wrap_open(mem_ctx, fname, 0, TDB_DEFAULT, O_RDWR|O_CREAT, 0600);
  66
  67         if (!tdb) {
  68                 DEBUG(0,("Failed to open %s\n", fname));
  69                 talloc_free(fname);
  70                 return NULL;
  71         }
  72         talloc_free(fname);
  73
  74         /**
  75          * Set a reseed function for the crypto random generator
  76          *
  77          * This avoids a problem where systems without /dev/urandom
  78          * could send the same challenge to multiple clients
  79          */
  80         set_rand_reseed_callback((void (*) (void *, int *))get_rand_seed, tdb);
  81
  82         /* Ensure that the reseed is done now, while we are root, etc */
  83         generate_random_buffer(&dummy, sizeof(dummy));
  84
  85         return tdb;
  86 }
  87
  88 /**
  89   connect to the secrets ldb
  90 */
  91 struct ldb_context *secrets_db_connect(TALLOC_CTX *mem_ctx,
  92                                         struct tevent_context *ev_ctx,
  93                                         struct loadparm_context *lp_ctx)
  94 {
  95         char *path;
  96         const char *url;
  97         struct ldb_context *ldb;
  98
  99         url = lp_secrets_url(lp_ctx);
 100         if (!url || !url[0]) {
 101                 return NULL;
 102         }
 103
 104         path = private_path(mem_ctx, lp_ctx, url);
 105         if (!path) {
 106                 return NULL;
 107         }
 108
 109         /* Secrets.ldb *must* always be local.  If we call for a
 110          * system_session() we will recurse */
 111         ldb = ldb_init(mem_ctx, ev_ctx);
 112         if (!ldb) {
 113                 talloc_free(path);
 114                 return NULL;
 115         }
 116
 117         ldb_set_modules_dir(ldb,
 118                             talloc_asprintf(ldb, "%s/ldb", lp_modulesdir(lp_ctx)));
 119
 120         if (ldb_connect(ldb, path, 0, NULL) != 0) {
 121                 talloc_free(path);
 122                 return NULL;
 123         }
 124
 125         /* the update_keytab module relies on this being setup */
 126         if (ldb_set_opaque(ldb, "loadparm", lp_ctx) != LDB_SUCCESS) {
 127                 talloc_free(path);
 128                 talloc_free(ldb);
 129                 return NULL;
 130         }
 131
 132         talloc_free(path);
 133
 134         return ldb;
 135 }
 136
 137 /**
 138  * Retrieve the domain SID from the secrets database.
 139  * @return pointer to a SID object if the SID could be obtained, NULL otherwise
 140  */
 141 struct dom_sid *secrets_get_domain_sid(TALLOC_CTX *mem_ctx,
 142                                        struct tevent_context *ev_ctx,
 143                                        struct loadparm_context *lp_ctx,
 144                                        const char *domain,
 145                                        char **errstring)
 146 {
 147         struct ldb_context *ldb;
 148         struct ldb_message *msg;
 149         int ldb_ret;
 150         const char *attrs[] = { "objectSid", NULL };
 151         struct dom_sid *result = NULL;
 152         const struct ldb_val *v;
 153         enum ndr_err_code ndr_err;
 154         *errstring = NULL;
 155
 156         ldb = secrets_db_connect(mem_ctx, ev_ctx, lp_ctx);
 157         if (ldb == NULL) {
 158                 DEBUG(5, ("secrets_db_connect failed\n"));
 159                 return NULL;
 160         }
 161
 162         ldb_ret = dsdb_search_one(ldb, ldb, &msg,
 163                               ldb_dn_new(mem_ctx, ldb, SECRETS_PRIMARY_DOMAIN_DN),
 164                               LDB_SCOPE_ONELEVEL,
 165                               attrs, 0, SECRETS_PRIMARY_DOMAIN_FILTER, domain);
 166
 167         if (ldb_ret != LDB_SUCCESS) {
 168                 *errstring = talloc_asprintf(mem_ctx, "Failed to find record for %s in %s: %s: %s",
 169                                              domain, ldb_get_opaque(ldb, "ldb_url"),
 170                                              ldb_strerror(ldb_ret), ldb_errstring(ldb));
 171                 return NULL;
 172         }
 173         v = ldb_msg_find_ldb_val(msg, "objectSid");
 174         if (v == NULL) {
 175                 *errstring = talloc_asprintf(mem_ctx, "Failed to find a SID on record for %s in %s",
 176                                              domain, ldb_get_opaque(ldb, "ldb_url"));
 177                 return NULL;
 178         }
 179         result = talloc(mem_ctx, struct dom_sid);
 180         if (result == NULL) {
 181                 talloc_free(ldb);
 182                 return NULL;
 183         }
 184
 185         ndr_err = ndr_pull_struct_blob(v, result, NULL, result,
 186                                        (ndr_pull_flags_fn_t)ndr_pull_dom_sid);
 187         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 188                 *errstring = talloc_asprintf(mem_ctx, "Failed to parse SID on record for %s in %s",
 189                                              domain, ldb_get_opaque(ldb, "ldb_url"));
 190                 talloc_free(result);
 191                 talloc_free(ldb);
 192                 return NULL;
 193         }
 194
 195         return result;
 196 }