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 "auth.h"
  23 #include "system/passwd.h"
  24 #include "smbd/smbd.h"
  25
  26 #undef DBGC_CLASS
  27 #define DBGC_CLASS DBGC_AUTH
  28
  29 extern userdom_struct current_user_info;
  30
  31 /****************************************************************************
  32  Support for server level security.
  33 ****************************************************************************/
  34
  35 static struct cli_state *server_cryptkey(TALLOC_CTX *mem_ctx)
  36 {
  37         struct cli_state *cli = NULL;
  38         char *desthost = NULL;
  39         struct sockaddr_storage dest_ss;
  40         const char *p;
  41         char *pserver = NULL;
  42         bool connected_ok = False;
  43         struct named_mutex *mutex = NULL;
  44         NTSTATUS status;
  45
  46         if (!(cli = cli_initialise()))
  47                 return NULL;
  48
  49         /* security = server just can't function with spnego */
  50         cli->use_spnego = False;
  51
  52         pserver = talloc_strdup(mem_ctx, lp_passwordserver());
  53         p = pserver;
  54
  55         while(next_token_talloc(mem_ctx, &p, &desthost, LIST_SEP)) {
  56
  57                 desthost = talloc_sub_basic(mem_ctx,
  58                                 current_user_info.smb_name,
  59                                 current_user_info.domain,
  60                                 desthost);
  61                 if (!desthost) {
  62                         return NULL;
  63                 }
  64                 strupper_m(desthost);
  65
  66                 if(!resolve_name( desthost, &dest_ss, 0x20, false)) {
  67                         DEBUG(1,("server_cryptkey: Can't resolve address for %s\n",desthost));
  68                         continue;
  69                 }
  70
  71                 if (ismyaddr((struct sockaddr *)&dest_ss)) {
  72                         DEBUG(1,("Password server loop - disabling password server %s\n",desthost));
  73                         continue;
  74                 }
  75
  76                 /* we use a mutex to prevent two connections at once - when a
  77                    Win2k PDC get two connections where one hasn't completed a
  78                    session setup yet it will send a TCP reset to the first
  79                    connection (tridge) */
  80
  81                 mutex = grab_named_mutex(talloc_tos(), desthost, 10);
  82                 if (mutex == NULL) {
  83                         cli_shutdown(cli);
  84                         return NULL;
  85                 }
  86
  87                 status = cli_connect(cli, desthost, &dest_ss);
  88                 if (NT_STATUS_IS_OK(status)) {
  89                         DEBUG(3,("connected to password server %s\n",desthost));
  90                         connected_ok = True;
  91                         break;
  92                 }
  93                 DEBUG(10,("server_cryptkey: failed to connect to server %s. Error %s\n",
  94                         desthost, nt_errstr(status) ));
  95                 TALLOC_FREE(mutex);
  96         }
  97
  98         if (!connected_ok) {
  99                 DEBUG(0,("password server not available\n"));
 100                 cli_shutdown(cli);
 101                 return NULL;
 102         }
 103
 104         if (!attempt_netbios_session_request(&cli, global_myname(),
 105                                              desthost, &dest_ss)) {
 106                 TALLOC_FREE(mutex);
 107                 DEBUG(1,("password server fails session request\n"));
 108                 cli_shutdown(cli);
 109                 return NULL;
 110         }
 111
 112         if (strequal(desthost,myhostname())) {
 113                 exit_server_cleanly("Password server loop!");
 114         }
 115
 116         DEBUG(3,("got session\n"));
 117
 118         status = cli_negprot(cli);
 119
 120         if (!NT_STATUS_IS_OK(status)) {
 121                 TALLOC_FREE(mutex);
 122                 DEBUG(1, ("%s rejected the negprot: %s\n",
 123                           desthost, nt_errstr(status)));
 124                 cli_shutdown(cli);
 125                 return NULL;
 126         }
 127
 128         if (cli->protocol < PROTOCOL_LANMAN2 ||
 129             !(cli->sec_mode & NEGOTIATE_SECURITY_USER_LEVEL)) {
 130                 TALLOC_FREE(mutex);
 131                 DEBUG(1,("%s isn't in user level security mode\n",desthost));
 132                 cli_shutdown(cli);
 133                 return NULL;
 134         }
 135
 136         /* Get the first session setup done quickly, to avoid silly
 137            Win2k bugs.  (The next connection to the server will kill
 138            this one...
 139         */
 140
 141         status = cli_session_setup(cli, "", "", 0, "", 0, "");
 142         if (!NT_STATUS_IS_OK(status)) {
 143                 TALLOC_FREE(mutex);
 144                 DEBUG(0,("%s rejected the initial session setup (%s)\n",
 145                          desthost, nt_errstr(status)));
 146                 cli_shutdown(cli);
 147                 return NULL;
 148         }
 149
 150         TALLOC_FREE(mutex);
 151
 152         DEBUG(3,("password server OK\n"));
 153
 154         return cli;
 155 }
 156
 157 struct server_security_state {
 158         struct cli_state *cli;
 159 };
 160
 161 /****************************************************************************
 162  Send a 'keepalive' packet down the cli pipe.
 163 ****************************************************************************/
 164
 165 static bool send_server_keepalive(const struct timeval *now,
 166                                   void *private_data)
 167 {
 168         struct server_security_state *state = talloc_get_type_abort(
 169                 private_data, struct server_security_state);
 170
 171         if (!state->cli || !state->cli->initialised) {
 172                 return False;
 173         }
 174
 175         if (send_keepalive(state->cli->fd)) {
 176                 return True;
 177         }
 178
 179         DEBUG( 2, ( "send_server_keepalive: password server keepalive "
 180                     "failed.\n"));
 181         cli_shutdown(state->cli);
 182         state->cli = NULL;
 183         return False;
 184 }
 185
 186 static int destroy_server_security(struct server_security_state *state)
 187 {
 188         if (state->cli) {
 189                 cli_shutdown(state->cli);
 190         }
 191         return 0;
 192 }
 193
 194 static struct server_security_state *make_server_security_state(struct cli_state *cli)
 195 {
 196         struct server_security_state *result;
 197
 198         if (!(result = talloc(NULL, struct server_security_state))) {
 199                 DEBUG(0, ("talloc failed\n"));
 200                 cli_shutdown(cli);
 201                 return NULL;
 202         }
 203
 204         result->cli = cli;
 205         talloc_set_destructor(result, destroy_server_security);
 206
 207         if (lp_keepalive() != 0) {
 208                 struct timeval interval;
 209                 interval.tv_sec = lp_keepalive();
 210                 interval.tv_usec = 0;
 211
 212                 if (event_add_idle(server_event_context(), result, interval,
 213                                    "server_security_keepalive",
 214                                    send_server_keepalive,
 215                                    result) == NULL) {
 216                         DEBUG(0, ("event_add_idle failed\n"));
 217                         TALLOC_FREE(result);
 218                         return NULL;
 219                 }
 220         }
 221
 222         return result;
 223 }
 224
 225 /****************************************************************************
 226  Get the challenge out of a password server.
 227 ****************************************************************************/
 228
 229 static DATA_BLOB auth_get_challenge_server(const struct auth_context *auth_context,
 230                                            void **my_private_data,
 231                                            TALLOC_CTX *mem_ctx)
 232 {
 233         struct cli_state *cli = server_cryptkey(mem_ctx);
 234
 235         if (cli) {
 236                 DEBUG(3,("using password server validation\n"));
 237
 238                 if ((cli->sec_mode & NEGOTIATE_SECURITY_CHALLENGE_RESPONSE) == 0) {
 239                         /* We can't work with unencrypted password servers
 240                            unless 'encrypt passwords = no' */
 241                         DEBUG(5,("make_auth_info_server: Server is unencrypted, no challenge available..\n"));
 242
 243                         /* However, it is still a perfectly fine connection
 244                            to pass that unencrypted password over */
 245                         *my_private_data =
 246                                 (void *)make_server_security_state(cli);
 247                         return data_blob_null;
 248                 } else if (cli->secblob.length < 8) {
 249                         /* We can't do much if we don't get a full challenge */
 250                         DEBUG(2,("make_auth_info_server: Didn't receive a full challenge from server\n"));
 251                         cli_shutdown(cli);
 252                         return data_blob_null;
 253                 }
 254
 255                 if (!(*my_private_data = (void *)make_server_security_state(cli))) {
 256                         return data_blob(NULL,0);
 257                 }
 258
 259                 /* The return must be allocated on the caller's mem_ctx, as our own will be
 260                    destoyed just after the call. */
 261                 return data_blob_talloc((TALLOC_CTX *)auth_context, cli->secblob.data,8);
 262         } else {
 263                 return data_blob_null;
 264         }
 265 }
 266
 267
 268 /****************************************************************************
 269  Check for a valid username and password in security=server mode.
 270   - Validate a password with the password server.
 271 ****************************************************************************/
 272
 273 static NTSTATUS check_smbserver_security(const struct auth_context *auth_context,
 274                                          void *my_private_data,
 275                                          TALLOC_CTX *mem_ctx,
 276                                          const struct auth_usersupplied_info *user_info,
 277                                          struct auth_serversupplied_info **server_info)
 278 {
 279         struct server_security_state *state = talloc_get_type_abort(
 280                 my_private_data, struct server_security_state);
 281         struct cli_state *cli;
 282         static bool tested_password_server = False;
 283         static bool bad_password_server = False;
 284         NTSTATUS nt_status = NT_STATUS_NOT_IMPLEMENTED;
 285         bool locally_made_cli = False;
 286
 287         DEBUG(10, ("Check auth for: [%s]\n", user_info->mapped.account_name));
 288
 289         cli = state->cli;
 290
 291         if (cli) {
 292         } else {
 293                 cli = server_cryptkey(mem_ctx);
 294                 locally_made_cli = True;
 295         }
 296
 297         if (!cli || !cli->initialised) {
 298                 DEBUG(1,("password server is not connected (cli not initialised)\n"));
 299                 return NT_STATUS_LOGON_FAILURE;
 300         }
 301
 302         if ((cli->sec_mode & NEGOTIATE_SECURITY_CHALLENGE_RESPONSE) == 0) {
 303                 if (user_info->password_state != AUTH_PASSWORD_PLAIN) {
 304                         DEBUG(1,("password server %s is plaintext, but we are encrypted. This just can't work :-(\n", cli->desthost));
 305                         return NT_STATUS_LOGON_FAILURE;
 306                 }
 307         } else {
 308                 if (memcmp(cli->secblob.data, auth_context->challenge.data, 8) != 0) {
 309                         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));
 310                         return NT_STATUS_LOGON_FAILURE;
 311                 }
 312         }
 313
 314         /*
 315          * Attempt a session setup with a totally incorrect password.
 316          * If this succeeds with the guest bit *NOT* set then the password
 317          * server is broken and is not correctly setting the guest bit. We
 318          * need to detect this as some versions of NT4.x are broken. JRA.
 319          */
 320
 321         /* I sure as hell hope that there aren't servers out there that take
 322          * NTLMv2 and have this bug, as we don't test for that...
 323          *  - abartlet@samba.org
 324          */
 325
 326         if ((!tested_password_server) && (lp_paranoid_server_security())) {
 327                 unsigned char badpass[24];
 328                 char *baduser = NULL;
 329
 330                 memset(badpass, 0x1f, sizeof(badpass));
 331
 332                 if((user_info->password.response.nt.length == sizeof(badpass)) &&
 333                    !memcmp(badpass, user_info->password.response.nt.data, sizeof(badpass))) {
 334                         /*
 335                          * Very unlikely, our random bad password is the same as the users
 336                          * password.
 337                          */
 338                         memset(badpass, badpass[0]+1, sizeof(badpass));
 339                 }
 340
 341                 baduser = talloc_asprintf(mem_ctx,
 342                                         "%s%s",
 343                                         INVALID_USER_PREFIX,
 344                                         global_myname());
 345                 if (!baduser) {
 346                         return NT_STATUS_NO_MEMORY;
 347                 }
 348
 349                 if (NT_STATUS_IS_OK(cli_session_setup(cli, baduser,
 350                                                       (char *)badpass,
 351                                                       sizeof(badpass),
 352                                                       (char *)badpass,
 353                                                       sizeof(badpass),
 354                                                       user_info->mapped.domain_name))) {
 355
 356                         /*
 357                          * We connected to the password server so we
 358                          * can say we've tested it.
 359                          */
 360                         tested_password_server = True;
 361
 362                         if ((SVAL(cli->inbuf,smb_vwv2) & 1) == 0) {
 363                                 DEBUG(0,("server_validate: password server %s allows users as non-guest \
 364 with a bad password.\n", cli->desthost));
 365                                 DEBUG(0,("server_validate: This is broken (and insecure) behaviour. Please do not \
 366 use this machine as the password server.\n"));
 367                                 cli_ulogoff(cli);
 368
 369                                 /*
 370                                  * Password server has the bug.
 371                                  */
 372                                 bad_password_server = True;
 373                                 return NT_STATUS_LOGON_FAILURE;
 374                         }
 375                         cli_ulogoff(cli);
 376                 }
 377         } else {
 378
 379                 /*
 380                  * We have already tested the password server.
 381                  * Fail immediately if it has the bug.
 382                  */
 383
 384                 if(bad_password_server) {
 385                         DEBUG(0,("server_validate: [1] password server %s allows users as non-guest \
 386 with a bad password.\n", cli->desthost));
 387                         DEBUG(0,("server_validate: [1] This is broken (and insecure) behaviour. Please do not \
 388 use this machine as the password server.\n"));
 389                         return NT_STATUS_LOGON_FAILURE;
 390                 }
 391         }
 392
 393         /*
 394          * Now we know the password server will correctly set the guest bit, or is
 395          * not guest enabled, we can try with the real password.
 396          */
 397         switch (user_info->password_state) {
 398         case AUTH_PASSWORD_PLAIN:
 399                 /* Plaintext available */
 400                 nt_status = cli_session_setup(
 401                         cli, user_info->client.account_name,
 402                         user_info->password.plaintext,
 403                         strlen(user_info->password.plaintext),
 404                         NULL, 0, user_info->mapped.domain_name);
 405                 break;
 406
 407         /* currently the hash values include a challenge-response as well */
 408         case AUTH_PASSWORD_HASH:
 409         case AUTH_PASSWORD_RESPONSE:
 410                 nt_status = cli_session_setup(
 411                         cli, user_info->client.account_name,
 412                         (char *)user_info->password.response.lanman.data,
 413                         user_info->password.response.lanman.length,
 414                         (char *)user_info->password.response.nt.data,
 415                         user_info->password.response.nt.length,
 416                         user_info->mapped.domain_name);
 417                 break;
 418         default:
 419                 DEBUG(0,("user_info constructed for user '%s' was invalid - password_state=%u invalid.\n",user_info->mapped.account_name, user_info->password_state));
 420                 nt_status = NT_STATUS_INTERNAL_ERROR;
 421         }
 422
 423         if (!NT_STATUS_IS_OK(nt_status)) {
 424                 DEBUG(1,("password server %s rejected the password: %s\n",
 425                          cli->desthost, nt_errstr(nt_status)));
 426         }
 427
 428         /* if logged in as guest then reject */
 429         if ((SVAL(cli->inbuf,smb_vwv2) & 1) != 0) {
 430                 DEBUG(1,("password server %s gave us guest only\n", cli->desthost));
 431                 nt_status = NT_STATUS_LOGON_FAILURE;
 432         }
 433
 434         cli_ulogoff(cli);
 435
 436         if (NT_STATUS_IS_OK(nt_status)) {
 437                 char *real_username = NULL;
 438                 struct passwd *pass = NULL;
 439
 440                 if ( (pass = smb_getpwnam(talloc_tos(), user_info->mapped.account_name,
 441                         &real_username, True )) != NULL )
 442                 {
 443                         nt_status = make_server_info_pw(server_info, pass->pw_name, pass);
 444                         TALLOC_FREE(pass);
 445                         TALLOC_FREE(real_username);
 446                 }
 447                 else
 448                 {
 449                         nt_status = NT_STATUS_NO_SUCH_USER;
 450                 }
 451         }
 452
 453         if (locally_made_cli) {
 454                 cli_shutdown(cli);
 455         }
 456
 457         return(nt_status);
 458 }
 459
 460 static NTSTATUS auth_init_smbserver(struct auth_context *auth_context, const char* param, auth_methods **auth_method)
 461 {
 462         struct auth_methods *result;
 463
 464         result = TALLOC_ZERO_P(auth_context, struct auth_methods);
 465         if (result == NULL) {
 466                 return NT_STATUS_NO_MEMORY;
 467         }
 468         result->name = "smbserver";
 469         result->auth = check_smbserver_security;
 470         result->get_chal = auth_get_challenge_server;
 471
 472         *auth_method = result;
 473         return NT_STATUS_OK;
 474 }
 475
 476 NTSTATUS auth_server_init(void)
 477 {
 478         return smb_register_auth(AUTH_INTERFACE_VERSION, "smbserver", auth_init_smbserver);
 479 }