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         /* security = server just can't function with spnego */
  47         int flags = CLI_FULL_CONNECTION_DONT_SPNEGO;
  48         uint16_t sec_mode = 0;
  49
  50         pserver = talloc_strdup(mem_ctx, lp_passwordserver());
  51         p = pserver;
  52
  53         while(next_token_talloc(mem_ctx, &p, &desthost, LIST_SEP)) {
  54
  55                 desthost = talloc_sub_basic(mem_ctx,
  56                                 current_user_info.smb_name,
  57                                 current_user_info.domain,
  58                                 desthost);
  59                 if (!desthost) {
  60                         return NULL;
  61                 }
  62                 strupper_m(desthost);
  63
  64                 if (strequal(desthost, myhostname())) {
  65                         DEBUG(1,("Password server loop - disabling "
  66                                  "password server %s\n", desthost));
  67                         continue;
  68                 }
  69
  70                 if(!resolve_name( desthost, &dest_ss, 0x20, false)) {
  71                         DEBUG(1,("server_cryptkey: Can't resolve address for %s\n",desthost));
  72                         continue;
  73                 }
  74
  75                 if (ismyaddr((struct sockaddr *)(void *)&dest_ss)) {
  76                         DEBUG(1,("Password server loop - disabling password server %s\n",desthost));
  77                         continue;
  78                 }
  79
  80                 /* we use a mutex to prevent two connections at once - when a
  81                    Win2k PDC get two connections where one hasn't completed a
  82                    session setup yet it will send a TCP reset to the first
  83                    connection (tridge) */
  84
  85                 mutex = grab_named_mutex(talloc_tos(), desthost, 10);
  86                 if (mutex == NULL) {
  87                         return NULL;
  88                 }
  89
  90                 status = cli_connect_nb(desthost, &dest_ss, 0, 0x20,
  91                                         lp_netbios_name(), SMB_SIGNING_DEFAULT,
  92                                         flags, &cli);
  93                 if (NT_STATUS_IS_OK(status)) {
  94                         DEBUG(3,("connected to password server %s\n",desthost));
  95                         connected_ok = True;
  96                         break;
  97                 }
  98                 DEBUG(10,("server_cryptkey: failed to connect to server %s. Error %s\n",
  99                         desthost, nt_errstr(status) ));
 100                 TALLOC_FREE(mutex);
 101         }
 102
 103         if (!connected_ok) {
 104                 DEBUG(0,("password server not available\n"));
 105                 return NULL;
 106         }
 107
 108         DEBUG(3,("got session\n"));
 109
 110         status = cli_negprot(cli, PROTOCOL_NT1);
 111
 112         if (!NT_STATUS_IS_OK(status)) {
 113                 TALLOC_FREE(mutex);
 114                 DEBUG(1, ("%s rejected the negprot: %s\n",
 115                           desthost, nt_errstr(status)));
 116                 cli_shutdown(cli);
 117                 return NULL;
 118         }
 119
 120         sec_mode = cli_state_security_mode(cli);
 121         if (cli_state_protocol(cli) < PROTOCOL_LANMAN2 ||
 122             !(sec_mode & NEGOTIATE_SECURITY_USER_LEVEL)) {
 123                 TALLOC_FREE(mutex);
 124                 DEBUG(1,("%s isn't in user level security mode\n",desthost));
 125                 cli_shutdown(cli);
 126                 return NULL;
 127         }
 128
 129         /* Get the first session setup done quickly, to avoid silly
 130            Win2k bugs.  (The next connection to the server will kill
 131            this one...
 132         */
 133
 134         status = cli_session_setup(cli, "", "", 0, "", 0, "");
 135         if (!NT_STATUS_IS_OK(status)) {
 136                 TALLOC_FREE(mutex);
 137                 DEBUG(0,("%s rejected the initial session setup (%s)\n",
 138                          desthost, nt_errstr(status)));
 139                 cli_shutdown(cli);
 140                 return NULL;
 141         }
 142
 143         TALLOC_FREE(mutex);
 144
 145         DEBUG(3,("password server OK\n"));
 146
 147         return cli;
 148 }
 149
 150 struct server_security_state {
 151         struct cli_state *cli;
 152 };
 153
 154 /****************************************************************************
 155  Send a 'keepalive' packet down the cli pipe.
 156 ****************************************************************************/
 157
 158 static bool send_server_keepalive(const struct timeval *now,
 159                                   void *private_data)
 160 {
 161         struct server_security_state *state = talloc_get_type_abort(
 162                 private_data, struct server_security_state);
 163         NTSTATUS status;
 164         unsigned char garbage[16];
 165
 166         if (!cli_state_is_connected(state->cli)) {
 167                 return false;
 168         }
 169
 170         /* Ping the server to keep the connection alive using SMBecho. */
 171         memset(garbage, 0xf0, sizeof(garbage));
 172         status = cli_echo(state->cli, 1, data_blob_const(garbage, sizeof(garbage)));
 173         if (NT_STATUS_IS_OK(status)) {
 174                 return true;
 175         }
 176
 177         DEBUG(2,("send_server_keepalive: password server SMBecho failed: %s\n",
 178                  nt_errstr(status)));
 179         cli_shutdown(state->cli);
 180         state->cli = NULL;
 181         return false;
 182 }
 183
 184 static int destroy_server_security(struct server_security_state *state)
 185 {
 186         if (state->cli) {
 187                 cli_shutdown(state->cli);
 188         }
 189         return 0;
 190 }
 191
 192 static struct server_security_state *make_server_security_state(struct cli_state *cli)
 193 {
 194         struct server_security_state *result;
 195
 196         if (!(result = talloc(NULL, struct server_security_state))) {
 197                 DEBUG(0, ("talloc failed\n"));
 198                 cli_shutdown(cli);
 199                 return NULL;
 200         }
 201
 202         result->cli = cli;
 203         talloc_set_destructor(result, destroy_server_security);
 204
 205         if (lp_keepalive() != 0) {
 206                 struct timeval interval;
 207                 interval.tv_sec = lp_keepalive();
 208                 interval.tv_usec = 0;
 209
 210                 if (event_add_idle(server_event_context(), result, interval,
 211                                    "server_security_keepalive",
 212                                    send_server_keepalive,
 213                                    result) == NULL) {
 214                         DEBUG(0, ("event_add_idle failed\n"));
 215                         TALLOC_FREE(result);
 216                         return NULL;
 217                 }
 218         }
 219
 220         return result;
 221 }
 222
 223 /****************************************************************************
 224  Get the challenge out of a password server.
 225 ****************************************************************************/
 226
 227 static DATA_BLOB auth_get_challenge_server(const struct auth_context *auth_context,
 228                                            void **my_private_data,
 229                                            TALLOC_CTX *mem_ctx)
 230 {
 231         struct cli_state *cli = server_cryptkey(mem_ctx);
 232
 233         if (cli) {
 234                 uint16_t sec_mode = cli_state_security_mode(cli);
 235                 const uint8_t *server_challenge = cli_state_server_challenge(cli);
 236
 237                 DEBUG(3,("using password server validation\n"));
 238
 239                 if ((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                 }
 250
 251                 if (!(*my_private_data = (void *)make_server_security_state(cli))) {
 252                         return data_blob(NULL,0);
 253                 }
 254
 255                 /* The return must be allocated on the caller's mem_ctx, as our own will be
 256                    destoyed just after the call. */
 257                 return data_blob_talloc(discard_const_p(TALLOC_CTX, auth_context), server_challenge ,8);
 258         } else {
 259                 return data_blob_null;
 260         }
 261 }
 262
 263
 264 /****************************************************************************
 265  Check for a valid username and password in security=server mode.
 266   - Validate a password with the password server.
 267 ****************************************************************************/
 268
 269 static NTSTATUS check_smbserver_security(const struct auth_context *auth_context,
 270                                          void *my_private_data,
 271                                          TALLOC_CTX *mem_ctx,
 272                                          const struct auth_usersupplied_info *user_info,
 273                                          struct auth_serversupplied_info **server_info)
 274 {
 275         struct server_security_state *state = NULL;
 276         struct cli_state *cli = NULL;
 277         static bool tested_password_server = False;
 278         static bool bad_password_server = False;
 279         NTSTATUS nt_status = NT_STATUS_NOT_IMPLEMENTED;
 280         bool locally_made_cli = False;
 281         uint16_t sec_mode = 0;
 282
 283         DEBUG(10, ("check_smbserver_security: Check auth for: [%s]\n",
 284                 user_info->mapped.account_name));
 285
 286         if (my_private_data == NULL) {
 287                 DEBUG(10,("check_smbserver_security: "
 288                         "password server is not connected\n"));
 289                 return NT_STATUS_LOGON_FAILURE;
 290         }
 291
 292         state = talloc_get_type_abort(my_private_data, struct server_security_state);
 293         cli = state->cli;
 294
 295         if (cli) {
 296         } else {
 297                 cli = server_cryptkey(mem_ctx);
 298                 locally_made_cli = True;
 299         }
 300
 301         if (!cli_state_is_connected(cli)) {
 302                 DEBUG(1,("password server is not connected (cli not initialised)\n"));
 303                 return NT_STATUS_LOGON_FAILURE;
 304         }
 305
 306         sec_mode = cli_state_security_mode(cli);
 307         if ((sec_mode & NEGOTIATE_SECURITY_CHALLENGE_RESPONSE) == 0) {
 308                 if (user_info->password_state != AUTH_PASSWORD_PLAIN) {
 309                         DEBUG(1,("password server %s is plaintext, but we are encrypted. This just can't work :-(\n", cli_state_remote_name(cli)));
 310                         return NT_STATUS_LOGON_FAILURE;
 311                 }
 312         } else {
 313                 const uint8_t *server_challenge = cli_state_server_challenge(cli);
 314
 315                 if (memcmp(server_challenge, auth_context->challenge.data, 8) != 0) {
 316                         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_state_remote_name(cli)));
 317                         return NT_STATUS_LOGON_FAILURE;
 318                 }
 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                 unsigned char badpass[24];
 335                 char *baduser = NULL;
 336
 337                 memset(badpass, 0x1f, sizeof(badpass));
 338
 339                 if((user_info->password.response.nt.length == sizeof(badpass)) &&
 340                    !memcmp(badpass, user_info->password.response.nt.data, sizeof(badpass))) {
 341                         /*
 342                          * Very unlikely, our random bad password is the same as the users
 343                          * password.
 344                          */
 345                         memset(badpass, badpass[0]+1, sizeof(badpass));
 346                 }
 347
 348                 baduser = talloc_asprintf(mem_ctx,
 349                                         "%s%s",
 350                                         INVALID_USER_PREFIX,
 351                                         lp_netbios_name());
 352                 if (!baduser) {
 353                         return NT_STATUS_NO_MEMORY;
 354                 }
 355
 356                 if (NT_STATUS_IS_OK(cli_session_setup(cli, baduser,
 357                                                       (char *)badpass,
 358                                                       sizeof(badpass),
 359                                                       (char *)badpass,
 360                                                       sizeof(badpass),
 361                                                       user_info->mapped.domain_name))) {
 362
 363                         /*
 364                          * We connected to the password server so we
 365                          * can say we've tested it.
 366                          */
 367                         tested_password_server = True;
 368
 369                         if (!cli->is_guestlogin) {
 370                                 DEBUG(0,("server_validate: password server %s allows users as non-guest \
 371 with a bad password.\n", cli_state_remote_name(cli)));
 372                                 DEBUG(0,("server_validate: This is broken (and insecure) behaviour. Please do not \
 373 use this machine as the password server.\n"));
 374                                 cli_ulogoff(cli);
 375
 376                                 /*
 377                                  * Password server has the bug.
 378                                  */
 379                                 bad_password_server = True;
 380                                 return NT_STATUS_LOGON_FAILURE;
 381                         }
 382                         cli_ulogoff(cli);
 383                 }
 384         } else {
 385
 386                 /*
 387                  * We have already tested the password server.
 388                  * Fail immediately if it has the bug.
 389                  */
 390
 391                 if(bad_password_server) {
 392                         DEBUG(0,("server_validate: [1] password server %s allows users as non-guest \
 393 with a bad password.\n", cli_state_remote_name(cli)));
 394                         DEBUG(0,("server_validate: [1] This is broken (and insecure) behaviour. Please do not \
 395 use this machine as the password server.\n"));
 396                         return NT_STATUS_LOGON_FAILURE;
 397                 }
 398         }
 399
 400         /*
 401          * Now we know the password server will correctly set the guest bit, or is
 402          * not guest enabled, we can try with the real password.
 403          */
 404         switch (user_info->password_state) {
 405         case AUTH_PASSWORD_PLAIN:
 406                 /* Plaintext available */
 407                 nt_status = cli_session_setup(
 408                         cli, user_info->client.account_name,
 409                         user_info->password.plaintext,
 410                         strlen(user_info->password.plaintext),
 411                         NULL, 0, user_info->mapped.domain_name);
 412                 break;
 413
 414         /* currently the hash values include a challenge-response as well */
 415         case AUTH_PASSWORD_HASH:
 416         case AUTH_PASSWORD_RESPONSE:
 417                 nt_status = cli_session_setup(
 418                         cli, user_info->client.account_name,
 419                         (char *)user_info->password.response.lanman.data,
 420                         user_info->password.response.lanman.length,
 421                         (char *)user_info->password.response.nt.data,
 422                         user_info->password.response.nt.length,
 423                         user_info->mapped.domain_name);
 424                 break;
 425         default:
 426                 DEBUG(0,("user_info constructed for user '%s' was invalid - password_state=%u invalid.\n",user_info->mapped.account_name, user_info->password_state));
 427                 nt_status = NT_STATUS_INTERNAL_ERROR;
 428         }
 429
 430         if (!NT_STATUS_IS_OK(nt_status)) {
 431                 DEBUG(1,("password server %s rejected the password: %s\n",
 432                          cli_state_remote_name(cli), nt_errstr(nt_status)));
 433         }
 434
 435         /* if logged in as guest then reject */
 436         if (cli->is_guestlogin) {
 437                 DEBUG(1,("password server %s gave us guest only\n",
 438                          cli_state_remote_name(cli)));
 439                 nt_status = NT_STATUS_LOGON_FAILURE;
 440         }
 441
 442         cli_ulogoff(cli);
 443
 444         if (NT_STATUS_IS_OK(nt_status)) {
 445                 char *real_username = NULL;
 446                 struct passwd *pass = NULL;
 447
 448                 if ( (pass = smb_getpwnam(talloc_tos(), user_info->mapped.account_name,
 449                         &real_username, True )) != NULL )
 450                 {
 451                         nt_status = make_server_info_pw(server_info, pass->pw_name, pass);
 452                         TALLOC_FREE(pass);
 453                         TALLOC_FREE(real_username);
 454                 }
 455                 else
 456                 {
 457                         nt_status = NT_STATUS_NO_SUCH_USER;
 458                 }
 459         }
 460
 461         if (locally_made_cli) {
 462                 cli_shutdown(cli);
 463         }
 464
 465         return(nt_status);
 466 }
 467
 468 static NTSTATUS auth_init_smbserver(struct auth_context *auth_context, const char* param, auth_methods **auth_method)
 469 {
 470         struct auth_methods *result;
 471
 472         result = talloc_zero(auth_context, struct auth_methods);
 473         if (result == NULL) {
 474                 return NT_STATUS_NO_MEMORY;
 475         }
 476         result->name = "smbserver";
 477         result->auth = check_smbserver_security;
 478         result->get_chal = auth_get_challenge_server;
 479
 480         *auth_method = result;
 481         return NT_STATUS_OK;
 482 }
 483
 484 NTSTATUS auth_server_init(void)
 485 {
 486         return smb_register_auth(AUTH_INTERFACE_VERSION, "smbserver", auth_init_smbserver);
 487 }