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 2 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, write to the Free Software
  19    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21
  22 #include "includes.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         fstring desthost;
  37         struct in_addr dest_ip;
  38         const char *p;
  39         char *pserver;
  40         BOOL connected_ok = False;
  41
  42         if (!(cli = cli_initialise()))
  43                 return NULL;
  44
  45         /* security = server just can't function with spnego */
  46         cli->use_spnego = False;
  47
  48         pserver = talloc_strdup(mem_ctx, lp_passwordserver());
  49         p = pserver;
  50
  51         while(next_token( &p, desthost, LIST_SEP, sizeof(desthost))) {
  52                 standard_sub_basic(current_user_info.smb_name, current_user_info.domain,
  53                                    desthost, sizeof(desthost));
  54                 strupper_m(desthost);
  55
  56                 if(!resolve_name( desthost, &dest_ip, 0x20)) {
  57                         DEBUG(1,("server_cryptkey: Can't resolve address for %s\n",desthost));
  58                         continue;
  59                 }
  60
  61                 if (ismyip(dest_ip)) {
  62                         DEBUG(1,("Password server loop - disabling password server %s\n",desthost));
  63                         continue;
  64                 }
  65
  66                 /* we use a mutex to prevent two connections at once - when a
  67                    Win2k PDC get two connections where one hasn't completed a
  68                    session setup yet it will send a TCP reset to the first
  69                    connection (tridge) */
  70
  71                 if (!grab_server_mutex(desthost)) {
  72                         return NULL;
  73                 }
  74
  75                 if (cli_connect(cli, desthost, &dest_ip)) {
  76                         DEBUG(3,("connected to password server %s\n",desthost));
  77                         connected_ok = True;
  78                         break;
  79                 }
  80         }
  81
  82         if (!connected_ok) {
  83                 release_server_mutex();
  84                 DEBUG(0,("password server not available\n"));
  85                 cli_shutdown(cli);
  86                 return NULL;
  87         }
  88
  89         if (!attempt_netbios_session_request(&cli, global_myname(),
  90                                              desthost, &dest_ip)) {
  91                 release_server_mutex();
  92                 DEBUG(1,("password server fails session request\n"));
  93                 cli_shutdown(cli);
  94                 return NULL;
  95         }
  96
  97         if (strequal(desthost,myhostname())) {
  98                 exit_server_cleanly("Password server loop!");
  99         }
 100
 101         DEBUG(3,("got session\n"));
 102
 103         if (!cli_negprot(cli)) {
 104                 DEBUG(1,("%s rejected the negprot\n",desthost));
 105                 release_server_mutex();
 106                 cli_shutdown(cli);
 107                 return NULL;
 108         }
 109
 110         if (cli->protocol < PROTOCOL_LANMAN2 ||
 111             !(cli->sec_mode & NEGOTIATE_SECURITY_USER_LEVEL)) {
 112                 DEBUG(1,("%s isn't in user level security mode\n",desthost));
 113                 release_server_mutex();
 114                 cli_shutdown(cli);
 115                 return NULL;
 116         }
 117
 118         /* Get the first session setup done quickly, to avoid silly
 119            Win2k bugs.  (The next connection to the server will kill
 120            this one...
 121         */
 122
 123         if (!NT_STATUS_IS_OK(cli_session_setup(cli, "", "", 0, "", 0,
 124                                                ""))) {
 125                 DEBUG(0,("%s rejected the initial session setup (%s)\n",
 126                          desthost, cli_errstr(cli)));
 127                 release_server_mutex();
 128                 cli_shutdown(cli);
 129                 return NULL;
 130         }
 131
 132         release_server_mutex();
 133
 134         DEBUG(3,("password server OK\n"));
 135
 136         return cli;
 137 }
 138
 139 struct server_security_state {
 140         struct cli_state *cli;
 141 };
 142
 143 /****************************************************************************
 144  Send a 'keepalive' packet down the cli pipe.
 145 ****************************************************************************/
 146
 147 static BOOL send_server_keepalive(const struct timeval *now,
 148                                   void *private_data)
 149 {
 150         struct server_security_state *state = talloc_get_type_abort(
 151                 private_data, struct server_security_state);
 152
 153         if (!state->cli || !state->cli->initialised) {
 154                 return False;
 155         }
 156
 157         if (send_keepalive(state->cli->fd)) {
 158                 return True;
 159         }
 160
 161         DEBUG( 2, ( "send_server_keepalive: password server keepalive "
 162                     "failed.\n"));
 163         cli_shutdown(state->cli);
 164         state->cli = NULL;
 165         return False;
 166 }
 167
 168 static int destroy_server_security(struct server_security_state *state)
 169 {
 170         if (state->cli) {
 171                 cli_shutdown(state->cli);
 172         }
 173         return 0;
 174 }
 175
 176 static struct server_security_state *make_server_security_state(struct cli_state *cli)
 177 {
 178         struct server_security_state *result;
 179
 180         if (!(result = talloc(NULL, struct server_security_state))) {
 181                 DEBUG(0, ("talloc failed\n"));
 182                 cli_shutdown(cli);
 183                 return NULL;
 184         }
 185
 186         result->cli = cli;
 187         talloc_set_destructor(result, destroy_server_security);
 188
 189         if (lp_keepalive() != 0) {
 190                 struct timeval interval;
 191                 interval.tv_sec = lp_keepalive();
 192                 interval.tv_usec = 0;
 193
 194                 if (event_add_idle(smbd_event_context(), result, interval,
 195                                    "server_security_keepalive",
 196                                    send_server_keepalive,
 197                                    result) == NULL) {
 198                         DEBUG(0, ("event_add_idle failed\n"));
 199                         TALLOC_FREE(result);
 200                         return NULL;
 201                 }
 202         }
 203
 204         return result;
 205 }
 206
 207 /****************************************************************************
 208  Get the challenge out of a password server.
 209 ****************************************************************************/
 210
 211 static DATA_BLOB auth_get_challenge_server(const struct auth_context *auth_context,
 212                                            void **my_private_data,
 213                                            TALLOC_CTX *mem_ctx)
 214 {
 215         struct cli_state *cli = server_cryptkey(mem_ctx);
 216
 217         if (cli) {
 218                 DEBUG(3,("using password server validation\n"));
 219
 220                 if ((cli->sec_mode & NEGOTIATE_SECURITY_CHALLENGE_RESPONSE) == 0) {
 221                         /* We can't work with unencrypted password servers
 222                            unless 'encrypt passwords = no' */
 223                         DEBUG(5,("make_auth_info_server: Server is unencrypted, no challenge available..\n"));
 224
 225                         /* However, it is still a perfectly fine connection
 226                            to pass that unencrypted password over */
 227                         *my_private_data =
 228                                 (void *)make_server_security_state(cli);
 229                         return data_blob_null;
 230
 231                 } else if (cli->secblob.length < 8) {
 232                         /* We can't do much if we don't get a full challenge */
 233                         DEBUG(2,("make_auth_info_server: Didn't receive a full challenge from server\n"));
 234                         cli_shutdown(cli);
 235                         return data_blob_null;
 236                 }
 237
 238                 if (!(*my_private_data = (void *)make_server_security_state(cli))) {
 239                         return data_blob_null;
 240                 }
 241
 242                 /* The return must be allocated on the caller's mem_ctx, as our own will be
 243                    destoyed just after the call. */
 244                 return data_blob_talloc(auth_context->mem_ctx, cli->secblob.data,8);
 245         } else {
 246                 return data_blob_null;
 247         }
 248 }
 249
 250
 251 /****************************************************************************
 252  Check for a valid username and password in security=server mode.
 253   - Validate a password with the password server.
 254 ****************************************************************************/
 255
 256 static NTSTATUS check_smbserver_security(const struct auth_context *auth_context,
 257                                          void *my_private_data,
 258                                          TALLOC_CTX *mem_ctx,
 259                                          const auth_usersupplied_info *user_info,
 260                                          auth_serversupplied_info **server_info)
 261 {
 262         struct cli_state *cli;
 263         static unsigned char badpass[24];
 264         static fstring baduser;
 265         static BOOL tested_password_server = False;
 266         static BOOL bad_password_server = False;
 267         NTSTATUS nt_status = NT_STATUS_NOT_IMPLEMENTED;
 268         BOOL locally_made_cli = False;
 269
 270         /*
 271          * Check that the requested domain is not our own machine name.
 272          * If it is, we should never check the PDC here, we use our own local
 273          * password file.
 274          */
 275
 276         if(is_myname(user_info->domain)) {
 277                 DEBUG(3,("check_smbserver_security: Requested domain was for this machine.\n"));
 278                 return nt_status;
 279         }
 280
 281         cli = (struct cli_state *)my_private_data;
 282
 283         if (cli) {
 284         } else {
 285                 cli = server_cryptkey(mem_ctx);
 286                 locally_made_cli = True;
 287         }
 288
 289         if (!cli || !cli->initialised) {
 290                 DEBUG(1,("password server is not connected (cli not initilised)\n"));
 291                 return NT_STATUS_LOGON_FAILURE;
 292         }
 293
 294         if ((cli->sec_mode & NEGOTIATE_SECURITY_CHALLENGE_RESPONSE) == 0) {
 295                 if (user_info->encrypted) {
 296                         DEBUG(1,("password server %s is plaintext, but we are encrypted. This just can't work :-(\n", cli->desthost));
 297                         return NT_STATUS_LOGON_FAILURE;
 298                 }
 299         } else {
 300                 if (memcmp(cli->secblob.data, auth_context->challenge.data, 8) != 0) {
 301                         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));
 302                         return NT_STATUS_LOGON_FAILURE;
 303                 }
 304         }
 305
 306         if(badpass[0] == 0)
 307                 memset(badpass, 0x1f, sizeof(badpass));
 308
 309         if((user_info->nt_resp.length == sizeof(badpass)) &&
 310            !memcmp(badpass, user_info->nt_resp.data, sizeof(badpass))) {
 311                 /*
 312                  * Very unlikely, our random bad password is the same as the users
 313                  * password.
 314                  */
 315                 memset(badpass, badpass[0]+1, sizeof(badpass));
 316         }
 317
 318         if(baduser[0] == 0) {
 319                 fstrcpy(baduser, INVALID_USER_PREFIX);
 320                 fstrcat(baduser, global_myname());
 321         }
 322
 323         /*
 324          * Attempt a session setup with a totally incorrect password.
 325          * If this succeeds with the guest bit *NOT* set then the password
 326          * server is broken and is not correctly setting the guest bit. We
 327          * need to detect this as some versions of NT4.x are broken. JRA.
 328          */
 329
 330         /* I sure as hell hope that there aren't servers out there that take
 331          * NTLMv2 and have this bug, as we don't test for that...
 332          *  - abartlet@samba.org
 333          */
 334
 335         if ((!tested_password_server) && (lp_paranoid_server_security())) {
 336                 if (NT_STATUS_IS_OK(cli_session_setup(cli, baduser,
 337                                                       (char *)badpass,
 338                                                       sizeof(badpass),
 339                                                       (char *)badpass,
 340                                                       sizeof(badpass),
 341                                                       user_info->domain))) {
 342
 343                         /*
 344                          * We connected to the password server so we
 345                          * can say we've tested it.
 346                          */
 347                         tested_password_server = True;
 348
 349                         if ((SVAL(cli->inbuf,smb_vwv2) & 1) == 0) {
 350                                 DEBUG(0,("server_validate: password server %s allows users as non-guest \
 351 with a bad password.\n", cli->desthost));
 352                                 DEBUG(0,("server_validate: This is broken (and insecure) behaviour. Please do not \
 353 use this machine as the password server.\n"));
 354                                 cli_ulogoff(cli);
 355
 356                                 /*
 357                                  * Password server has the bug.
 358                                  */
 359                                 bad_password_server = True;
 360                                 return NT_STATUS_LOGON_FAILURE;
 361                         }
 362                         cli_ulogoff(cli);
 363                 }
 364         } else {
 365
 366                 /*
 367                  * We have already tested the password server.
 368                  * Fail immediately if it has the bug.
 369                  */
 370
 371                 if(bad_password_server) {
 372                         DEBUG(0,("server_validate: [1] password server %s allows users as non-guest \
 373 with a bad password.\n", cli->desthost));
 374                         DEBUG(0,("server_validate: [1] This is broken (and insecure) behaviour. Please do not \
 375 use this machine as the password server.\n"));
 376                         return NT_STATUS_LOGON_FAILURE;
 377                 }
 378         }
 379
 380         /*
 381          * Now we know the password server will correctly set the guest bit, or is
 382          * not guest enabled, we can try with the real password.
 383          */
 384
 385         if (!user_info->encrypted) {
 386                 /* Plaintext available */
 387                 nt_status = cli_session_setup(
 388                         cli, user_info->smb_name,
 389                         (char *)user_info->plaintext_password.data,
 390                         user_info->plaintext_password.length,
 391                         NULL, 0, user_info->domain);
 392
 393         } else {
 394                 nt_status = cli_session_setup(
 395                         cli, user_info->smb_name,
 396                         (char *)user_info->lm_resp.data,
 397                         user_info->lm_resp.length,
 398                         (char *)user_info->nt_resp.data,
 399                         user_info->nt_resp.length,
 400                         user_info->domain);
 401         }
 402
 403         if (!NT_STATUS_IS_OK(nt_status)) {
 404                 DEBUG(1,("password server %s rejected the password: %s\n",
 405                          cli->desthost, nt_errstr(nt_status)));
 406         }
 407
 408         /* if logged in as guest then reject */
 409         if ((SVAL(cli->inbuf,smb_vwv2) & 1) != 0) {
 410                 DEBUG(1,("password server %s gave us guest only\n", cli->desthost));
 411                 nt_status = NT_STATUS_LOGON_FAILURE;
 412         }
 413
 414         cli_ulogoff(cli);
 415
 416         if (NT_STATUS_IS_OK(nt_status)) {
 417                 fstring real_username;
 418                 struct passwd *pass;
 419
 420                 if ( (pass = smb_getpwnam( NULL, user_info->internal_username,
 421                         real_username, True )) != NULL )
 422                 {
 423                         /* if a real user check pam account restrictions */
 424                         /* only really perfomed if "obey pam restriction" is true */
 425                         nt_status = smb_pam_accountcheck(pass->pw_name);
 426                         if (  !NT_STATUS_IS_OK(nt_status)) {
 427                                 DEBUG(1, ("PAM account restriction prevents user login\n"));
 428                         } else {
 429
 430                                 nt_status = make_server_info_pw(server_info, pass->pw_name, pass);
 431                         }
 432                         TALLOC_FREE(pass);
 433                 }
 434                 else
 435                 {
 436                         nt_status = NT_STATUS_NO_SUCH_USER;
 437                 }
 438         }
 439
 440         if (locally_made_cli) {
 441                 cli_shutdown(cli);
 442         }
 443
 444         return(nt_status);
 445 }
 446
 447 static NTSTATUS auth_init_smbserver(struct auth_context *auth_context, const char* param, auth_methods **auth_method)
 448 {
 449         if (!make_auth_methods(auth_context, auth_method)) {
 450                 return NT_STATUS_NO_MEMORY;
 451         }
 452         (*auth_method)->name = "smbserver";
 453         (*auth_method)->auth = check_smbserver_security;
 454         (*auth_method)->get_chal = auth_get_challenge_server;
 455         return NT_STATUS_OK;
 456 }
 457
 458 NTSTATUS auth_server_init(void)
 459 {
 460         return smb_register_auth(AUTH_INTERFACE_VERSION, "smbserver", auth_init_smbserver);
 461 }