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
  35 /**
  36  * Use a TDB to store an incrementing random seed.
  37  *
  38  * Initialised to the current pid, the very first time Samba starts,
  39  * and incremented by one each time it is needed.
  40  *
  41  * @note Not called by systems with a working /dev/urandom.
  42  */
  43 static void get_rand_seed(struct tdb_wrap *secretsdb, int *new_seed)
  44 {
  45         *new_seed = getpid();
  46         if (secretsdb != NULL) {
  47                 tdb_change_int32_atomic(secretsdb->tdb, "INFO/random_seed", new_seed, 1);
  48         }
  49 }
  50
  51 /**
  52  * open up the secrets database
  53  */
  54 struct tdb_wrap *secrets_init(TALLOC_CTX *mem_ctx, struct loadparm_context *lp_ctx)
  55 {
  56         char *fname;
  57         uint8_t dummy;
  58         struct tdb_wrap *tdb;
  59
  60         fname = private_path(mem_ctx, lp_ctx, "secrets.tdb");
  61
  62         tdb = tdb_wrap_open(mem_ctx, fname, 0, TDB_DEFAULT, O_RDWR|O_CREAT, 0600);
  63
  64         if (!tdb) {
  65                 DEBUG(0,("Failed to open %s\n", fname));
  66                 talloc_free(fname);
  67                 return NULL;
  68         }
  69         talloc_free(fname);
  70
  71         /**
  72          * Set a reseed function for the crypto random generator
  73          *
  74          * This avoids a problem where systems without /dev/urandom
  75          * could send the same challenge to multiple clients
  76          */
  77         set_rand_reseed_callback((void (*) (void *, int *))get_rand_seed, tdb);
  78
  79         /* Ensure that the reseed is done now, while we are root, etc */
  80         generate_random_buffer(&dummy, sizeof(dummy));
  81
  82         return tdb;
  83 }
  84
  85 /**
  86   connect to the secrets ldb
  87 */
  88 struct ldb_context *secrets_db_connect(TALLOC_CTX *mem_ctx,
  89                                         struct tevent_context *ev_ctx,
  90                                         struct loadparm_context *lp_ctx)
  91 {
  92         char *path;
  93         const char *url;
  94         struct ldb_context *ldb;
  95
  96         url = lp_secrets_url(lp_ctx);
  97         if (!url || !url[0]) {
  98                 return NULL;
  99         }
 100
 101         path = private_path(mem_ctx, lp_ctx, url);
 102         if (!path) {
 103                 return NULL;
 104         }
 105
 106         /* Secrets.ldb *must* always be local.  If we call for a
 107          * system_session() we will recurse */
 108         ldb = ldb_init(mem_ctx, ev_ctx);
 109         if (!ldb) {
 110                 talloc_free(path);
 111                 return NULL;
 112         }
 113
 114         ldb_set_modules_dir(ldb,
 115                             talloc_asprintf(ldb, "%s/ldb", lp_modulesdir(lp_ctx)));
 116
 117         if (ldb_connect(ldb, path, 0, NULL) != 0) {
 118                 talloc_free(path);
 119                 return NULL;
 120         }
 121
 122         /* the update_keytab module relies on this being setup */
 123         if (ldb_set_opaque(ldb, "loadparm", lp_ctx) != LDB_SUCCESS) {
 124                 talloc_free(path);
 125                 talloc_free(ldb);
 126                 return NULL;
 127         }
 128
 129         talloc_free(path);
 130
 131         return ldb;
 132 }
 133
 134 /**
 135  * Retrieve the domain SID from the secrets database.
 136  * @return pointer to a SID object if the SID could be obtained, NULL otherwise
 137  */
 138 struct dom_sid *secrets_get_domain_sid(TALLOC_CTX *mem_ctx,
 139                                        struct tevent_context *ev_ctx,
 140                                        struct loadparm_context *lp_ctx,
 141                                        const char *domain)
 142 {
 143         struct ldb_context *ldb;
 144         struct ldb_message **msgs;
 145         int ldb_ret;
 146         const char *attrs[] = { "objectSid", NULL };
 147         struct dom_sid *result = NULL;
 148         const struct ldb_val *v;
 149         enum ndr_err_code ndr_err;
 150
 151         ldb = secrets_db_connect(mem_ctx, ev_ctx, lp_ctx);
 152         if (ldb == NULL) {
 153                 DEBUG(5, ("secrets_db_connect failed\n"));
 154                 return NULL;
 155         }
 156
 157         ldb_ret = gendb_search(ldb, ldb,
 158                                ldb_dn_new(mem_ctx, ldb, SECRETS_PRIMARY_DOMAIN_DN),
 159                                &msgs, attrs,
 160                                SECRETS_PRIMARY_DOMAIN_FILTER, domain);
 161
 162         if (ldb_ret == -1) {
 163                 DEBUG(5, ("Error searching for domain SID for %s: %s",
 164                           domain, ldb_errstring(ldb)));
 165                 talloc_free(ldb);
 166                 return NULL;
 167         }
 168
 169         if (ldb_ret == 0) {
 170                 DEBUG(5, ("Did not find domain record for %s\n", domain));
 171                 talloc_free(ldb);
 172                 return NULL;
 173         }
 174
 175         if (ldb_ret > 1) {
 176                 DEBUG(5, ("Found more than one (%d) domain records for %s\n",
 177                           ldb_ret, domain));
 178                 talloc_free(ldb);
 179                 return NULL;
 180         }
 181
 182         v = ldb_msg_find_ldb_val(msgs[0], "objectSid");
 183         if (v == NULL) {
 184                 DEBUG(0, ("Domain object for %s does not contain a SID!\n",
 185                           domain));
 186                 return NULL;
 187         }
 188         result = talloc(mem_ctx, struct dom_sid);
 189         if (result == NULL) {
 190                 talloc_free(ldb);
 191                 return NULL;
 192         }
 193
 194         ndr_err = ndr_pull_struct_blob(v, result, NULL, result,
 195                                        (ndr_pull_flags_fn_t)ndr_pull_dom_sid);
 196         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 197                 talloc_free(result);
 198                 talloc_free(ldb);
 199                 return NULL;
 200         }
 201
 202         return result;
 203 }