source3/auth/auth_server.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Authenticate to a remote server
   4    Copyright (C) Andrew Tridgell 1992-1998
   5    Copyright (C) Andrew Bartlett 2001
   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 #include "includes.h"
  22 #include "system/passwd.h"
  23
  24 #undef DBGC_CLASS
  25 #define DBGC_CLASS DBGC_AUTH
  26
  27 extern userdom_struct current_user_info;
  28
  29 /****************************************************************************
  30  Support for server level security.
  31 ****************************************************************************/
  32
  33 static struct cli_state *server_cryptkey(TALLOC_CTX *mem_ctx)
  34 {
  35         struct cli_state *cli = NULL;
  36         char *desthost = NULL;
  37         struct sockaddr_storage dest_ss;
  38         const char *p;
  39         char *pserver = NULL;
  40         bool connected_ok = False;
  41         struct named_mutex *mutex = NULL;
  42         NTSTATUS status;
  43
  44         if (!(cli = cli_initialise()))
  45                 return NULL;
  46
  47         /* security = server just can't function with spnego */
  48         cli->use_spnego = False;
  49
  50         pserver = talloc_strdup(mem_ctx, lp_passwordserver());
  51         p = pserver;
  52
  53         while(next_token_talloc(mem_ctx, &p, &desthost, LIST_SEP)) {
  54
  55                 desthost = talloc_sub_basic(mem_ctx,
  56                                 current_user_info.smb_name,
  57                                 current_user_info.domain,
  58                                 desthost);
  59                 if (!desthost) {
  60                         return NULL;
  61                 }
  62                 strupper_m(desthost);
  63
  64                 if(!resolve_name( desthost, &dest_ss, 0x20, false)) {
  65                         DEBUG(1,("server_cryptkey: Can't resolve address for %s\n",desthost));
  66                         continue;
  67                 }
  68
  69                 if (ismyaddr((struct sockaddr *)&dest_ss)) {
  70                         DEBUG(1,("Password server loop - disabling password server %s\n",desthost));
  71                         continue;
  72                 }
  73
  74                 /* we use a mutex to prevent two connections at once - when a
  75                    Win2k PDC get two connections where one hasn't completed a
  76                    session setup yet it will send a TCP reset to the first
  77                    connection (tridge) */
  78
  79                 mutex = grab_named_mutex(talloc_tos(), desthost, 10);
  80                 if (mutex == NULL) {
  81                         cli_shutdown(cli);
  82                         return NULL;
  83                 }
  84
  85                 status = cli_connect(cli, desthost, &dest_ss);
  86                 if (NT_STATUS_IS_OK(status)) {
  87                         DEBUG(3,("connected to password server %s\n",desthost));
  88                         connected_ok = True;
  89                         break;
  90                 }
  91                 DEBUG(10,("server_cryptkey: failed to connect to server %s. Error %s\n",
  92                         desthost, nt_errstr(status) ));
  93                 TALLOC_FREE(mutex);
  94         }
  95
  96         if (!connected_ok) {
  97                 DEBUG(0,("password server not available\n"));
  98                 cli_shutdown(cli);
  99                 return NULL;
 100         }
 101
 102         if (!attempt_netbios_session_request(&cli, global_myname(),
 103                                              desthost, &dest_ss)) {
 104                 TALLOC_FREE(mutex);
 105                 DEBUG(1,("password server fails session request\n"));
 106                 cli_shutdown(cli);
 107                 return NULL;
 108         }
 109
 110         if (strequal(desthost,myhostname())) {
 111                 exit_server_cleanly("Password server loop!");
 112         }
 113
 114         DEBUG(3,("got session\n"));
 115
 116         status = cli_negprot(cli);
 117
 118         if (!NT_STATUS_IS_OK(status)) {
 119                 TALLOC_FREE(mutex);
 120                 DEBUG(1, ("%s rejected the negprot: %s\n",
 121                           desthost, nt_errstr(status)));
 122                 cli_shutdown(cli);
 123                 return NULL;
 124         }
 125
 126         if (cli->protocol < PROTOCOL_LANMAN2 ||
 127             !(cli->sec_mode & NEGOTIATE_SECURITY_USER_LEVEL)) {
 128                 TALLOC_FREE(mutex);
 129                 DEBUG(1,("%s isn't in user level security mode\n",desthost));
 130                 cli_shutdown(cli);
 131                 return NULL;
 132         }
 133
 134         /* Get the first session setup done quickly, to avoid silly
 135            Win2k bugs.  (The next connection to the server will kill
 136            this one...
 137         */
 138
 139         status = cli_session_setup(cli, "", "", 0, "", 0, "");
 140         if (!NT_STATUS_IS_OK(status)) {
 141                 TALLOC_FREE(mutex);
 142                 DEBUG(0,("%s rejected the initial session setup (%s)\n",
 143                          desthost, nt_errstr(status)));
 144                 cli_shutdown(cli);
 145                 return NULL;
 146         }
 147
 148         TALLOC_FREE(mutex);
 149
 150         DEBUG(3,("password server OK\n"));
 151
 152         return cli;
 153 }
 154
 155 struct server_security_state {
 156         struct cli_state *cli;
 157 };
 158
 159 /****************************************************************************
 160  Send a 'keepalive' packet down the cli pipe.
 161 ****************************************************************************/
 162
 163 static bool send_server_keepalive(const struct timeval *now,
 164                                   void *private_data)
 165 {
 166         struct server_security_state *state = talloc_get_type_abort(
 167                 private_data, struct server_security_state);
 168
 169         if (!state->cli || !state->cli->initialised) {
 170                 return False;
 171         }
 172
 173         if (send_keepalive(state->cli->fd)) {
 174                 return True;
 175         }
 176
 177         DEBUG( 2, ( "send_server_keepalive: password server keepalive "
 178                     "failed.\n"));
 179         cli_shutdown(state->cli);
 180         state->cli = NULL;
 181         return False;
 182 }
 183
 184 static int destroy_server_security(struct server_security_state *state)
 185 {
 186         if (state->cli) {
 187                 cli_shutdown(state->cli);
 188         }
 189         return 0;
 190 }
 191
 192 static struct server_security_state *make_server_security_state(struct cli_state *cli)
 193 {
 194         struct server_security_state *result;
 195
 196         if (!(result = talloc(NULL, struct server_security_state))) {
 197                 DEBUG(0, ("talloc failed\n"));
 198                 cli_shutdown(cli);
 199                 return NULL;
 200         }
 201
 202         result->cli = cli;
 203         talloc_set_destructor(result, destroy_server_security);
 204
 205         if (lp_keepalive() != 0) {
 206                 struct timeval interval;
 207                 interval.tv_sec = lp_keepalive();
 208                 interval.tv_usec = 0;
 209
 210                 if (event_add_idle(server_event_context(), result, interval,
 211                                    "server_security_keepalive",
 212                                    send_server_keepalive,
 213                                    result) == NULL) {
 214                         DEBUG(0, ("event_add_idle failed\n"));
 215                         TALLOC_FREE(result);
 216                         return NULL;
 217                 }
 218         }
 219
 220         return result;
 221 }
 222
 223 /****************************************************************************
 224  Get the challenge out of a password server.
 225 ****************************************************************************/
 226
 227 static DATA_BLOB auth_get_challenge_server(const struct auth_context *auth_context,
 228                                            void **my_private_data,
 229                                            TALLOC_CTX *mem_ctx)
 230 {
 231         struct cli_state *cli = server_cryptkey(mem_ctx);
 232
 233         if (cli) {
 234                 DEBUG(3,("using password server validation\n"));
 235
 236                 if ((cli->sec_mode & NEGOTIATE_SECURITY_CHALLENGE_RESPONSE) == 0) {
 237                         /* We can't work with unencrypted password servers
 238                            unless 'encrypt passwords = no' */
 239                         DEBUG(5,("make_auth_info_server: Server is unencrypted, no challenge available..\n"));
 240
 241                         /* However, it is still a perfectly fine connection
 242                            to pass that unencrypted password over */
 243                         *my_private_data =
 244                                 (void *)make_server_security_state(cli);
 245                         return data_blob_null;
 246                 } else if (cli->secblob.length < 8) {
 247                         /* We can't do much if we don't get a full challenge */
 248                         DEBUG(2,("make_auth_info_server: Didn't receive a full challenge from server\n"));
 249                         cli_shutdown(cli);
 250                         return data_blob_null;
 251                 }
 252
 253                 if (!(*my_private_data = (void *)make_server_security_state(cli))) {
 254                         return data_blob(NULL,0);
 255                 }
 256
 257                 /* The return must be allocated on the caller's mem_ctx, as our own will be
 258                    destoyed just after the call. */
 259                 return data_blob_talloc((TALLOC_CTX *)auth_context, cli->secblob.data,8);
 260         } else {
 261                 return data_blob_null;
 262         }
 263 }
 264
 265
 266 /****************************************************************************
 267  Check for a valid username and password in security=server mode.
 268   - Validate a password with the password server.
 269 ****************************************************************************/
 270
 271 static NTSTATUS check_smbserver_security(const struct auth_context *auth_context,
 272                                          void *my_private_data,
 273                                          TALLOC_CTX *mem_ctx,
 274                                          const struct auth_usersupplied_info *user_info,
 275                                          struct auth_serversupplied_info **server_info)
 276 {
 277         struct server_security_state *state = talloc_get_type_abort(
 278                 my_private_data, struct server_security_state);
 279         struct cli_state *cli;
 280         static bool tested_password_server = False;
 281         static bool bad_password_server = False;
 282         NTSTATUS nt_status = NT_STATUS_NOT_IMPLEMENTED;
 283         bool locally_made_cli = False;
 284
 285         DEBUG(10, ("Check auth for: [%s]\n", user_info->mapped.account_name));
 286
 287         cli = state->cli;
 288
 289         if (cli) {
 290         } else {
 291                 cli = server_cryptkey(mem_ctx);
 292                 locally_made_cli = True;
 293         }
 294
 295         if (!cli || !cli->initialised) {
 296                 DEBUG(1,("password server is not connected (cli not initialised)\n"));
 297                 return NT_STATUS_LOGON_FAILURE;
 298         }
 299
 300         if ((cli->sec_mode & NEGOTIATE_SECURITY_CHALLENGE_RESPONSE) == 0) {
 301                 if (user_info->password_state != AUTH_PASSWORD_PLAIN) {
 302                         DEBUG(1,("password server %s is plaintext, but we are encrypted. This just can't work :-(\n", cli->desthost));
 303                         return NT_STATUS_LOGON_FAILURE;
 304                 }
 305         } else {
 306                 if (memcmp(cli->secblob.data, auth_context->challenge.data, 8) != 0) {
 307                         DEBUG(1,("the challenge that the password server (%s) supplied us is not the one we gave our client. This just can't work :-(\n", cli->desthost));
 308                         return NT_STATUS_LOGON_FAILURE;
 309                 }
 310         }
 311
 312         /*
 313          * Attempt a session setup with a totally incorrect password.
 314          * If this succeeds with the guest bit *NOT* set then the password
 315          * server is broken and is not correctly setting the guest bit. We
 316          * need to detect this as some versions of NT4.x are broken. JRA.
 317          */
 318
 319         /* I sure as hell hope that there aren't servers out there that take
 320          * NTLMv2 and have this bug, as we don't test for that...
 321          *  - abartlet@samba.org
 322          */
 323
 324         if ((!tested_password_server) && (lp_paranoid_server_security())) {
 325                 unsigned char badpass[24];
 326                 char *baduser = NULL;
 327
 328                 memset(badpass, 0x1f, sizeof(badpass));
 329
 330                 if((user_info->password.response.nt.length == sizeof(badpass)) &&
 331                    !memcmp(badpass, user_info->password.response.nt.data, sizeof(badpass))) {
 332                         /*
 333                          * Very unlikely, our random bad password is the same as the users
 334                          * password.
 335                          */
 336                         memset(badpass, badpass[0]+1, sizeof(badpass));
 337                 }
 338
 339                 baduser = talloc_asprintf(mem_ctx,
 340                                         "%s%s",
 341                                         INVALID_USER_PREFIX,
 342                                         global_myname());
 343                 if (!baduser) {
 344                         return NT_STATUS_NO_MEMORY;
 345                 }
 346
 347                 if (NT_STATUS_IS_OK(cli_session_setup(cli, baduser,
 348                                                       (char *)badpass,
 349                                                       sizeof(badpass),
 350                                                       (char *)badpass,
 351                                                       sizeof(badpass),
 352                                                       user_info->mapped.domain_name))) {
 353
 354                         /*
 355                          * We connected to the password server so we
 356                          * can say we've tested it.
 357                          */
 358                         tested_password_server = True;
 359
 360                         if ((SVAL(cli->inbuf,smb_vwv2) & 1) == 0) {
 361                                 DEBUG(0,("server_validate: password server %s allows users as non-guest \
 362 with a bad password.\n", cli->desthost));
 363                                 DEBUG(0,("server_validate: This is broken (and insecure) behaviour. Please do not \
 364 use this machine as the password server.\n"));
 365                                 cli_ulogoff(cli);
 366
 367                                 /*
 368                                  * Password server has the bug.
 369                                  */
 370                                 bad_password_server = True;
 371                                 return NT_STATUS_LOGON_FAILURE;
 372                         }
 373                         cli_ulogoff(cli);
 374                 }
 375         } else {
 376
 377                 /*
 378                  * We have already tested the password server.
 379                  * Fail immediately if it has the bug.
 380                  */
 381
 382                 if(bad_password_server) {
 383                         DEBUG(0,("server_validate: [1] password server %s allows users as non-guest \
 384 with a bad password.\n", cli->desthost));
 385                         DEBUG(0,("server_validate: [1] This is broken (and insecure) behaviour. Please do not \
 386 use this machine as the password server.\n"));
 387                         return NT_STATUS_LOGON_FAILURE;
 388                 }
 389         }
 390
 391         /*
 392          * Now we know the password server will correctly set the guest bit, or is
 393          * not guest enabled, we can try with the real password.
 394          */
 395         switch (user_info->password_state) {
 396         case AUTH_PASSWORD_PLAIN:
 397                 /* Plaintext available */
 398                 nt_status = cli_session_setup(
 399                         cli, user_info->client.account_name,
 400                         user_info->password.plaintext,
 401                         strlen(user_info->password.plaintext),
 402                         NULL, 0, user_info->mapped.domain_name);
 403                 break;
 404
 405         /* currently the hash values include a challenge-response as well */
 406         case AUTH_PASSWORD_HASH:
 407         case AUTH_PASSWORD_RESPONSE:
 408                 nt_status = cli_session_setup(
 409                         cli, user_info->client.account_name,
 410                         (char *)user_info->password.response.lanman.data,
 411                         user_info->password.response.lanman.length,
 412                         (char *)user_info->password.response.nt.data,
 413                         user_info->password.response.nt.length,
 414                         user_info->mapped.domain_name);
 415                 break;
 416         default:
 417                 DEBUG(0,("user_info constructed for user '%s' was invalid - password_state=%u invalid.\n",user_info->mapped.account_name, user_info->password_state));
 418                 nt_status = NT_STATUS_INTERNAL_ERROR;
 419         }
 420
 421         if (!NT_STATUS_IS_OK(nt_status)) {
 422                 DEBUG(1,("password server %s rejected the password: %s\n",
 423                          cli->desthost, nt_errstr(nt_status)));
 424         }
 425
 426         /* if logged in as guest then reject */
 427         if ((SVAL(cli->inbuf,smb_vwv2) & 1) != 0) {
 428                 DEBUG(1,("password server %s gave us guest only\n", cli->desthost));
 429                 nt_status = NT_STATUS_LOGON_FAILURE;
 430         }
 431
 432         cli_ulogoff(cli);
 433
 434         if (NT_STATUS_IS_OK(nt_status)) {
 435                 char *real_username = NULL;
 436                 struct passwd *pass = NULL;
 437
 438                 if ( (pass = smb_getpwnam(talloc_tos(), user_info->mapped.account_name,
 439                         &real_username, True )) != NULL )
 440                 {
 441                         nt_status = make_server_info_pw(server_info, pass->pw_name, pass);
 442                         TALLOC_FREE(pass);
 443                         TALLOC_FREE(real_username);
 444                 }
 445                 else
 446                 {
 447                         nt_status = NT_STATUS_NO_SUCH_USER;
 448                 }
 449         }
 450
 451         if (locally_made_cli) {
 452                 cli_shutdown(cli);
 453         }
 454
 455         return(nt_status);
 456 }
 457
 458 static NTSTATUS auth_init_smbserver(struct auth_context *auth_context, const char* param, auth_methods **auth_method)
 459 {
 460         struct auth_methods *result;
 461
 462         result = TALLOC_ZERO_P(auth_context, struct auth_methods);
 463         if (result == NULL) {
 464                 return NT_STATUS_NO_MEMORY;
 465         }
 466         result->name = "smbserver";
 467         result->auth = check_smbserver_security;
 468         result->get_chal = auth_get_challenge_server;
 469
 470         *auth_method = result;
 471         return NT_STATUS_OK;
 472 }
 473
 474 NTSTATUS auth_server_init(void)
 475 {
 476         return smb_register_auth(AUTH_INTERFACE_VERSION, "smbserver", auth_init_smbserver);
 477 }