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