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 #include "libsmb/libsmb.h"
  26
  27 #undef DBGC_CLASS
  28 #define DBGC_CLASS DBGC_AUTH
  29
  30 extern userdom_struct current_user_info;
  31
  32 /****************************************************************************
  33  Support for server level security.
  34 ****************************************************************************/
  35
  36 static struct cli_state *server_cryptkey(TALLOC_CTX *mem_ctx)
  37 {
  38         struct cli_state *cli = NULL;
  39         char *desthost = NULL;
  40         struct sockaddr_storage dest_ss;
  41         const char *p;
  42         char *pserver = NULL;
  43         bool connected_ok = False;
  44         struct named_mutex *mutex = NULL;
  45         NTSTATUS status;
  46
  47         if (!(cli = cli_initialise()))
  48                 return NULL;
  49
  50         /* security = server just can't function with spnego */
  51         cli->use_spnego = False;
  52
  53         pserver = talloc_strdup(mem_ctx, lp_passwordserver());
  54         p = pserver;
  55
  56         while(next_token_talloc(mem_ctx, &p, &desthost, LIST_SEP)) {
  57
  58                 desthost = talloc_sub_basic(mem_ctx,
  59                                 current_user_info.smb_name,
  60                                 current_user_info.domain,
  61                                 desthost);
  62                 if (!desthost) {
  63                         return NULL;
  64                 }
  65                 strupper_m(desthost);
  66
  67                 if(!resolve_name( desthost, &dest_ss, 0x20, false)) {
  68                         DEBUG(1,("server_cryptkey: Can't resolve address for %s\n",desthost));
  69                         continue;
  70                 }
  71
  72                 if (ismyaddr((struct sockaddr *)&dest_ss)) {
  73                         DEBUG(1,("Password server loop - disabling password server %s\n",desthost));
  74                         continue;
  75                 }
  76
  77                 /* we use a mutex to prevent two connections at once - when a
  78                    Win2k PDC get two connections where one hasn't completed a
  79                    session setup yet it will send a TCP reset to the first
  80                    connection (tridge) */
  81
  82                 mutex = grab_named_mutex(talloc_tos(), desthost, 10);
  83                 if (mutex == NULL) {
  84                         cli_shutdown(cli);
  85                         return NULL;
  86                 }
  87
  88                 status = cli_connect(cli, desthost, &dest_ss);
  89                 if (NT_STATUS_IS_OK(status)) {
  90                         DEBUG(3,("connected to password server %s\n",desthost));
  91                         connected_ok = True;
  92                         break;
  93                 }
  94                 DEBUG(10,("server_cryptkey: failed to connect to server %s. Error %s\n",
  95                         desthost, nt_errstr(status) ));
  96                 TALLOC_FREE(mutex);
  97         }
  98
  99         if (!connected_ok) {
 100                 DEBUG(0,("password server not available\n"));
 101                 cli_shutdown(cli);
 102                 return NULL;
 103         }
 104
 105         if (!attempt_netbios_session_request(&cli, global_myname(),
 106                                              desthost, &dest_ss)) {
 107                 TALLOC_FREE(mutex);
 108                 DEBUG(1,("password server fails session request\n"));
 109                 cli_shutdown(cli);
 110                 return NULL;
 111         }
 112
 113         if (strequal(desthost,myhostname())) {
 114                 exit_server_cleanly("Password server loop!");
 115         }
 116
 117         DEBUG(3,("got session\n"));
 118
 119         status = cli_negprot(cli);
 120
 121         if (!NT_STATUS_IS_OK(status)) {
 122                 TALLOC_FREE(mutex);
 123                 DEBUG(1, ("%s rejected the negprot: %s\n",
 124                           desthost, nt_errstr(status)));
 125                 cli_shutdown(cli);
 126                 return NULL;
 127         }
 128
 129         if (cli->protocol < PROTOCOL_LANMAN2 ||
 130             !(cli->sec_mode & NEGOTIATE_SECURITY_USER_LEVEL)) {
 131                 TALLOC_FREE(mutex);
 132                 DEBUG(1,("%s isn't in user level security mode\n",desthost));
 133                 cli_shutdown(cli);
 134                 return NULL;
 135         }
 136
 137         /* Get the first session setup done quickly, to avoid silly
 138            Win2k bugs.  (The next connection to the server will kill
 139            this one...
 140         */
 141
 142         status = cli_session_setup(cli, "", "", 0, "", 0, "");
 143         if (!NT_STATUS_IS_OK(status)) {
 144                 TALLOC_FREE(mutex);
 145                 DEBUG(0,("%s rejected the initial session setup (%s)\n",
 146                          desthost, nt_errstr(status)));
 147                 cli_shutdown(cli);
 148                 return NULL;
 149         }
 150
 151         TALLOC_FREE(mutex);
 152
 153         DEBUG(3,("password server OK\n"));
 154
 155         return cli;
 156 }
 157
 158 struct server_security_state {
 159         struct cli_state *cli;
 160 };
 161
 162 /****************************************************************************
 163  Send a 'keepalive' packet down the cli pipe.
 164 ****************************************************************************/
 165
 166 static bool send_server_keepalive(const struct timeval *now,
 167                                   void *private_data)
 168 {
 169         struct server_security_state *state = talloc_get_type_abort(
 170                 private_data, struct server_security_state);
 171
 172         if (!state->cli || !state->cli->initialised) {
 173                 return False;
 174         }
 175
 176         if (send_keepalive(state->cli->fd)) {
 177                 return True;
 178         }
 179
 180         DEBUG( 2, ( "send_server_keepalive: password server keepalive "
 181                     "failed.\n"));
 182         cli_shutdown(state->cli);
 183         state->cli = NULL;
 184         return False;
 185 }
 186
 187 static int destroy_server_security(struct server_security_state *state)
 188 {
 189         if (state->cli) {
 190                 cli_shutdown(state->cli);
 191         }
 192         return 0;
 193 }
 194
 195 static struct server_security_state *make_server_security_state(struct cli_state *cli)
 196 {
 197         struct server_security_state *result;
 198
 199         if (!(result = talloc(NULL, struct server_security_state))) {
 200                 DEBUG(0, ("talloc failed\n"));
 201                 cli_shutdown(cli);
 202                 return NULL;
 203         }
 204
 205         result->cli = cli;
 206         talloc_set_destructor(result, destroy_server_security);
 207
 208         if (lp_keepalive() != 0) {
 209                 struct timeval interval;
 210                 interval.tv_sec = lp_keepalive();
 211                 interval.tv_usec = 0;
 212
 213                 if (event_add_idle(server_event_context(), result, interval,
 214                                    "server_security_keepalive",
 215                                    send_server_keepalive,
 216                                    result) == NULL) {
 217                         DEBUG(0, ("event_add_idle failed\n"));
 218                         TALLOC_FREE(result);
 219                         return NULL;
 220                 }
 221         }
 222
 223         return result;
 224 }
 225
 226 /****************************************************************************
 227  Get the challenge out of a password server.
 228 ****************************************************************************/
 229
 230 static DATA_BLOB auth_get_challenge_server(const struct auth_context *auth_context,
 231                                            void **my_private_data,
 232                                            TALLOC_CTX *mem_ctx)
 233 {
 234         struct cli_state *cli = server_cryptkey(mem_ctx);
 235
 236         if (cli) {
 237                 DEBUG(3,("using password server validation\n"));
 238
 239                 if ((cli->sec_mode & NEGOTIATE_SECURITY_CHALLENGE_RESPONSE) == 0) {
 240                         /* We can't work with unencrypted password servers
 241                            unless 'encrypt passwords = no' */
 242                         DEBUG(5,("make_auth_info_server: Server is unencrypted, no challenge available..\n"));
 243
 244                         /* However, it is still a perfectly fine connection
 245                            to pass that unencrypted password over */
 246                         *my_private_data =
 247                                 (void *)make_server_security_state(cli);
 248                         return data_blob_null;
 249                 } else if (cli->secblob.length < 8) {
 250                         /* We can't do much if we don't get a full challenge */
 251                         DEBUG(2,("make_auth_info_server: Didn't receive a full challenge from server\n"));
 252                         cli_shutdown(cli);
 253                         return data_blob_null;
 254                 }
 255
 256                 if (!(*my_private_data = (void *)make_server_security_state(cli))) {
 257                         return data_blob(NULL,0);
 258                 }
 259
 260                 /* The return must be allocated on the caller's mem_ctx, as our own will be
 261                    destoyed just after the call. */
 262                 return data_blob_talloc((TALLOC_CTX *)auth_context, cli->secblob.data,8);
 263         } else {
 264                 return data_blob_null;
 265         }
 266 }
 267
 268
 269 /****************************************************************************
 270  Check for a valid username and password in security=server mode.
 271   - Validate a password with the password server.
 272 ****************************************************************************/
 273
 274 static NTSTATUS check_smbserver_security(const struct auth_context *auth_context,
 275                                          void *my_private_data,
 276                                          TALLOC_CTX *mem_ctx,
 277                                          const struct auth_usersupplied_info *user_info,
 278                                          struct auth_serversupplied_info **server_info)
 279 {
 280         struct server_security_state *state = talloc_get_type_abort(
 281                 my_private_data, struct server_security_state);
 282         struct cli_state *cli;
 283         static bool tested_password_server = False;
 284         static bool bad_password_server = False;
 285         NTSTATUS nt_status = NT_STATUS_NOT_IMPLEMENTED;
 286         bool locally_made_cli = False;
 287
 288         DEBUG(10, ("Check auth for: [%s]\n", user_info->mapped.account_name));
 289
 290         cli = state->cli;
 291
 292         if (cli) {
 293         } else {
 294                 cli = server_cryptkey(mem_ctx);
 295                 locally_made_cli = True;
 296         }
 297
 298         if (!cli || !cli->initialised) {
 299                 DEBUG(1,("password server is not connected (cli not initialised)\n"));
 300                 return NT_STATUS_LOGON_FAILURE;
 301         }
 302
 303         if ((cli->sec_mode & NEGOTIATE_SECURITY_CHALLENGE_RESPONSE) == 0) {
 304                 if (user_info->password_state != AUTH_PASSWORD_PLAIN) {
 305                         DEBUG(1,("password server %s is plaintext, but we are encrypted. This just can't work :-(\n", cli->desthost));
 306                         return NT_STATUS_LOGON_FAILURE;
 307                 }
 308         } else {
 309                 if (memcmp(cli->secblob.data, auth_context->challenge.data, 8) != 0) {
 310                         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));
 311                         return NT_STATUS_LOGON_FAILURE;
 312                 }
 313         }
 314
 315         /*
 316          * Attempt a session setup with a totally incorrect password.
 317          * If this succeeds with the guest bit *NOT* set then the password
 318          * server is broken and is not correctly setting the guest bit. We
 319          * need to detect this as some versions of NT4.x are broken. JRA.
 320          */
 321
 322         /* I sure as hell hope that there aren't servers out there that take
 323          * NTLMv2 and have this bug, as we don't test for that...
 324          *  - abartlet@samba.org
 325          */
 326
 327         if ((!tested_password_server) && (lp_paranoid_server_security())) {
 328                 unsigned char badpass[24];
 329                 char *baduser = NULL;
 330
 331                 memset(badpass, 0x1f, sizeof(badpass));
 332
 333                 if((user_info->password.response.nt.length == sizeof(badpass)) &&
 334                    !memcmp(badpass, user_info->password.response.nt.data, sizeof(badpass))) {
 335                         /*
 336                          * Very unlikely, our random bad password is the same as the users
 337                          * password.
 338                          */
 339                         memset(badpass, badpass[0]+1, sizeof(badpass));
 340                 }
 341
 342                 baduser = talloc_asprintf(mem_ctx,
 343                                         "%s%s",
 344                                         INVALID_USER_PREFIX,
 345                                         global_myname());
 346                 if (!baduser) {
 347                         return NT_STATUS_NO_MEMORY;
 348                 }
 349
 350                 if (NT_STATUS_IS_OK(cli_session_setup(cli, baduser,
 351                                                       (char *)badpass,
 352                                                       sizeof(badpass),
 353                                                       (char *)badpass,
 354                                                       sizeof(badpass),
 355                                                       user_info->mapped.domain_name))) {
 356
 357                         /*
 358                          * We connected to the password server so we
 359                          * can say we've tested it.
 360                          */
 361                         tested_password_server = True;
 362
 363                         if ((SVAL(cli->inbuf,smb_vwv2) & 1) == 0) {
 364                                 DEBUG(0,("server_validate: password server %s allows users as non-guest \
 365 with a bad password.\n", cli->desthost));
 366                                 DEBUG(0,("server_validate: This is broken (and insecure) behaviour. Please do not \
 367 use this machine as the password server.\n"));
 368                                 cli_ulogoff(cli);
 369
 370                                 /*
 371                                  * Password server has the bug.
 372                                  */
 373                                 bad_password_server = True;
 374                                 return NT_STATUS_LOGON_FAILURE;
 375                         }
 376                         cli_ulogoff(cli);
 377                 }
 378         } else {
 379
 380                 /*
 381                  * We have already tested the password server.
 382                  * Fail immediately if it has the bug.
 383                  */
 384
 385                 if(bad_password_server) {
 386                         DEBUG(0,("server_validate: [1] password server %s allows users as non-guest \
 387 with a bad password.\n", cli->desthost));
 388                         DEBUG(0,("server_validate: [1] This is broken (and insecure) behaviour. Please do not \
 389 use this machine as the password server.\n"));
 390                         return NT_STATUS_LOGON_FAILURE;
 391                 }
 392         }
 393
 394         /*
 395          * Now we know the password server will correctly set the guest bit, or is
 396          * not guest enabled, we can try with the real password.
 397          */
 398         switch (user_info->password_state) {
 399         case AUTH_PASSWORD_PLAIN:
 400                 /* Plaintext available */
 401                 nt_status = cli_session_setup(
 402                         cli, user_info->client.account_name,
 403                         user_info->password.plaintext,
 404                         strlen(user_info->password.plaintext),
 405                         NULL, 0, user_info->mapped.domain_name);
 406                 break;
 407
 408         /* currently the hash values include a challenge-response as well */
 409         case AUTH_PASSWORD_HASH:
 410         case AUTH_PASSWORD_RESPONSE:
 411                 nt_status = cli_session_setup(
 412                         cli, user_info->client.account_name,
 413                         (char *)user_info->password.response.lanman.data,
 414                         user_info->password.response.lanman.length,
 415                         (char *)user_info->password.response.nt.data,
 416                         user_info->password.response.nt.length,
 417                         user_info->mapped.domain_name);
 418                 break;
 419         default:
 420                 DEBUG(0,("user_info constructed for user '%s' was invalid - password_state=%u invalid.\n",user_info->mapped.account_name, user_info->password_state));
 421                 nt_status = NT_STATUS_INTERNAL_ERROR;
 422         }
 423
 424         if (!NT_STATUS_IS_OK(nt_status)) {
 425                 DEBUG(1,("password server %s rejected the password: %s\n",
 426                          cli->desthost, nt_errstr(nt_status)));
 427         }
 428
 429         /* if logged in as guest then reject */
 430         if (cli->is_guestlogin) {
 431                 DEBUG(1,("password server %s gave us guest only\n", cli->desthost));
 432                 nt_status = NT_STATUS_LOGON_FAILURE;
 433         }
 434
 435         cli_ulogoff(cli);
 436
 437         if (NT_STATUS_IS_OK(nt_status)) {
 438                 char *real_username = NULL;
 439                 struct passwd *pass = NULL;
 440
 441                 if ( (pass = smb_getpwnam(talloc_tos(), user_info->mapped.account_name,
 442                         &real_username, True )) != NULL )
 443                 {
 444                         nt_status = make_server_info_pw(server_info, pass->pw_name, pass);
 445                         TALLOC_FREE(pass);
 446                         TALLOC_FREE(real_username);
 447                 }
 448                 else
 449                 {
 450                         nt_status = NT_STATUS_NO_SUCH_USER;
 451                 }
 452         }
 453
 454         if (locally_made_cli) {
 455                 cli_shutdown(cli);
 456         }
 457
 458         return(nt_status);
 459 }
 460
 461 static NTSTATUS auth_init_smbserver(struct auth_context *auth_context, const char* param, auth_methods **auth_method)
 462 {
 463         struct auth_methods *result;
 464
 465         result = TALLOC_ZERO_P(auth_context, struct auth_methods);
 466         if (result == NULL) {
 467                 return NT_STATUS_NO_MEMORY;
 468         }
 469         result->name = "smbserver";
 470         result->auth = check_smbserver_security;
 471         result->get_chal = auth_get_challenge_server;
 472
 473         *auth_method = result;
 474         return NT_STATUS_OK;
 475 }
 476
 477 NTSTATUS auth_server_init(void)
 478 {
 479         return smb_register_auth(AUTH_INTERFACE_VERSION, "smbserver", auth_init_smbserver);
 480 }