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 "lib/util/tdb_wrap.h"
  29 #include "lib/ldb-samba/ldb_wrap.h"
  30 #include <ldb.h>
  31 #include "../lib/util/util_tdb.h"
  32 #include "librpc/gen_ndr/ndr_security.h"
  33 #include "dsdb/samdb/samdb.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 randseed database and set the random number generator callback
  53  */
  54 bool randseed_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 = lpcfg_private_path(mem_ctx, lp_ctx, "randseed.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 false;
  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 true;
  83 }
  84
  85 /**
  86   connect to the secrets ldb
  87 */
  88 struct ldb_context *secrets_db_connect(TALLOC_CTX *mem_ctx,
  89                                         struct loadparm_context *lp_ctx)
  90 {
  91         return ldb_wrap_connect(mem_ctx, NULL, lp_ctx, "secrets.ldb",
  92                                NULL, NULL, 0);
  93 }
  94
  95 /**
  96  * Retrieve the domain SID from the secrets database.
  97  * @return pointer to a SID object if the SID could be obtained, NULL otherwise
  98  */
  99 struct dom_sid *secrets_get_domain_sid(TALLOC_CTX *mem_ctx,
 100                                        struct loadparm_context *lp_ctx,
 101                                        const char *domain,
 102                                        enum netr_SchannelType *sec_channel_type,
 103                                        char **errstring)
 104 {
 105         struct ldb_context *ldb;
 106         struct ldb_message *msg;
 107         int ldb_ret;
 108         const char *attrs[] = { "objectSid", "secureChannelType", NULL };
 109         struct dom_sid *result = NULL;
 110         const struct ldb_val *v;
 111         enum ndr_err_code ndr_err;
 112
 113         *errstring = NULL;
 114
 115         ldb = secrets_db_connect(mem_ctx, lp_ctx);
 116         if (ldb == NULL) {
 117                 DEBUG(5, ("secrets_db_connect failed\n"));
 118                 return NULL;
 119         }
 120
 121         ldb_ret = dsdb_search_one(ldb, ldb, &msg,
 122                               ldb_dn_new(mem_ctx, ldb, SECRETS_PRIMARY_DOMAIN_DN),
 123                               LDB_SCOPE_ONELEVEL,
 124                               attrs, 0, SECRETS_PRIMARY_DOMAIN_FILTER, domain);
 125
 126         if (ldb_ret != LDB_SUCCESS) {
 127                 *errstring = talloc_asprintf(mem_ctx, "Failed to find record for %s in %s: %s: %s",
 128                                              domain, (char *) ldb_get_opaque(ldb, "ldb_url"),
 129                                              ldb_strerror(ldb_ret), ldb_errstring(ldb));
 130                 return NULL;
 131         }
 132         v = ldb_msg_find_ldb_val(msg, "objectSid");
 133         if (v == NULL) {
 134                 *errstring = talloc_asprintf(mem_ctx, "Failed to find a SID on record for %s in %s",
 135                                              domain, (char *) ldb_get_opaque(ldb, "ldb_url"));
 136                 return NULL;
 137         }
 138
 139         if (sec_channel_type) {
 140                 int t;
 141                 t = ldb_msg_find_attr_as_int(msg, "secureChannelType", -1);
 142                 if (t == -1) {
 143                         *errstring = talloc_asprintf(mem_ctx, "Failed to find secureChannelType for %s in %s",
 144                                                      domain, (char *) ldb_get_opaque(ldb, "ldb_url"));
 145                         return NULL;
 146                 }
 147                 *sec_channel_type = t;
 148         }
 149
 150         result = talloc(mem_ctx, struct dom_sid);
 151         if (result == NULL) {
 152                 talloc_free(ldb);
 153                 return NULL;
 154         }
 155
 156         ndr_err = ndr_pull_struct_blob(v, result, result,
 157                                        (ndr_pull_flags_fn_t)ndr_pull_dom_sid);
 158         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 159                 *errstring = talloc_asprintf(mem_ctx, "Failed to parse SID on record for %s in %s",
 160                                              domain, (char *) ldb_get_opaque(ldb, "ldb_url"));
 161                 talloc_free(result);
 162                 talloc_free(ldb);
 163                 return NULL;
 164         }
 165
 166         return result;
 167 }
 168
 169 char *keytab_name_from_msg(TALLOC_CTX *mem_ctx, struct ldb_context *ldb, struct ldb_message *msg)
 170 {
 171         const char *krb5keytab = ldb_msg_find_attr_as_string(msg, "krb5Keytab", NULL);
 172         if (krb5keytab) {
 173                 return talloc_strdup(mem_ctx, krb5keytab);
 174         } else {
 175                 char *file_keytab;
 176                 char *relative_path;
 177                 const char *privateKeytab = ldb_msg_find_attr_as_string(msg, "privateKeytab", NULL);
 178                 if (!privateKeytab) {
 179                         return NULL;
 180                 }
 181
 182                 relative_path = ldb_relative_path(ldb, mem_ctx, privateKeytab);
 183                 if (!relative_path) {
 184                         return NULL;
 185                 }
 186                 file_keytab = talloc_asprintf(mem_ctx, "FILE:%s", relative_path);
 187                 talloc_free(relative_path);
 188                 return file_keytab;
 189         }
 190         return NULL;
 191 }
 192