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