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