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(), Undefined, flags, &cli);
  92                 if (NT_STATUS_IS_OK(status)) {
  93                         DEBUG(3,("connected to password server %s\n",desthost));
  94                         connected_ok = True;
  95                         break;
  96                 }
  97                 DEBUG(10,("server_cryptkey: failed to connect to server %s. Error %s\n",
  98                         desthost, nt_errstr(status) ));
  99                 TALLOC_FREE(mutex);
 100         }
 101
 102         if (!connected_ok) {
 103                 DEBUG(0,("password server not available\n"));
 104                 return NULL;
 105         }
 106
 107         DEBUG(3,("got session\n"));
 108
 109         status = cli_negprot(cli, PROTOCOL_NT1);
 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         sec_mode = cli_state_security_mode(cli);
 120         if (cli_state_protocol(cli) < PROTOCOL_LANMAN2 ||
 121             !(sec_mode & NEGOTIATE_SECURITY_USER_LEVEL)) {
 122                 TALLOC_FREE(mutex);
 123                 DEBUG(1,("%s isn't in user level security mode\n",desthost));
 124                 cli_shutdown(cli);
 125                 return NULL;
 126         }
 127
 128         /* Get the first session setup done quickly, to avoid silly
 129            Win2k bugs.  (The next connection to the server will kill
 130            this one...
 131         */
 132
 133         status = cli_session_setup(cli, "", "", 0, "", 0, "");
 134         if (!NT_STATUS_IS_OK(status)) {
 135                 TALLOC_FREE(mutex);
 136                 DEBUG(0,("%s rejected the initial session setup (%s)\n",
 137                          desthost, nt_errstr(status)));
 138                 cli_shutdown(cli);
 139                 return NULL;
 140         }
 141
 142         TALLOC_FREE(mutex);
 143
 144         DEBUG(3,("password server OK\n"));
 145
 146         return cli;
 147 }
 148
 149 struct server_security_state {
 150         struct cli_state *cli;
 151 };
 152
 153 /****************************************************************************
 154  Send a 'keepalive' packet down the cli pipe.
 155 ****************************************************************************/
 156
 157 static bool send_server_keepalive(const struct timeval *now,
 158                                   void *private_data)
 159 {
 160         struct server_security_state *state = talloc_get_type_abort(
 161                 private_data, struct server_security_state);
 162         NTSTATUS status;
 163         unsigned char garbage[16];
 164
 165         if (!cli_state_is_connected(state->cli)) {
 166                 return false;
 167         }
 168
 169         /* Ping the server to keep the connection alive using SMBecho. */
 170         memset(garbage, 0xf0, sizeof(garbage));
 171         status = cli_echo(state->cli, 1, data_blob_const(garbage, sizeof(garbage)));
 172         if (NT_STATUS_IS_OK(status)) {
 173                 return true;
 174         }
 175
 176         DEBUG(2,("send_server_keepalive: password server SMBecho failed: %s\n",
 177                  nt_errstr(status)));
 178         cli_shutdown(state->cli);
 179         state->cli = NULL;
 180         return false;
 181 }
 182
 183 static int destroy_server_security(struct server_security_state *state)
 184 {
 185         if (state->cli) {
 186                 cli_shutdown(state->cli);
 187         }
 188         return 0;
 189 }
 190
 191 static struct server_security_state *make_server_security_state(struct cli_state *cli)
 192 {
 193         struct server_security_state *result;
 194
 195         if (!(result = talloc(NULL, struct server_security_state))) {
 196                 DEBUG(0, ("talloc failed\n"));
 197                 cli_shutdown(cli);
 198                 return NULL;
 199         }
 200
 201         result->cli = cli;
 202         talloc_set_destructor(result, destroy_server_security);
 203
 204         if (lp_keepalive() != 0) {
 205                 struct timeval interval;
 206                 interval.tv_sec = lp_keepalive();
 207                 interval.tv_usec = 0;
 208
 209                 if (event_add_idle(server_event_context(), result, interval,
 210                                    "server_security_keepalive",
 211                                    send_server_keepalive,
 212                                    result) == NULL) {
 213                         DEBUG(0, ("event_add_idle failed\n"));
 214                         TALLOC_FREE(result);
 215                         return NULL;
 216                 }
 217         }
 218
 219         return result;
 220 }
 221
 222 /****************************************************************************
 223  Get the challenge out of a password server.
 224 ****************************************************************************/
 225
 226 static DATA_BLOB auth_get_challenge_server(const struct auth_context *auth_context,
 227                                            void **my_private_data,
 228                                            TALLOC_CTX *mem_ctx)
 229 {
 230         struct cli_state *cli = server_cryptkey(mem_ctx);
 231
 232         if (cli) {
 233                 uint16_t sec_mode = cli_state_security_mode(cli);
 234                 const uint8_t *server_challenge = cli_state_server_challenge(cli);
 235
 236                 DEBUG(3,("using password server validation\n"));
 237
 238                 if ((sec_mode & NEGOTIATE_SECURITY_CHALLENGE_RESPONSE) == 0) {
 239                         /* We can't work with unencrypted password servers
 240                            unless 'encrypt passwords = no' */
 241                         DEBUG(5,("make_auth_info_server: Server is unencrypted, no challenge available..\n"));
 242
 243                         /* However, it is still a perfectly fine connection
 244                            to pass that unencrypted password over */
 245                         *my_private_data =
 246                                 (void *)make_server_security_state(cli);
 247                         return data_blob_null;
 248                 }
 249
 250                 if (!(*my_private_data = (void *)make_server_security_state(cli))) {
 251                         return data_blob(NULL,0);
 252                 }
 253
 254                 /* The return must be allocated on the caller's mem_ctx, as our own will be
 255                    destoyed just after the call. */
 256                 return data_blob_talloc(discard_const_p(TALLOC_CTX, auth_context), server_challenge ,8);
 257         } else {
 258                 return data_blob_null;
 259         }
 260 }
 261
 262
 263 /****************************************************************************
 264  Check for a valid username and password in security=server mode.
 265   - Validate a password with the password server.
 266 ****************************************************************************/
 267
 268 static NTSTATUS check_smbserver_security(const struct auth_context *auth_context,
 269                                          void *my_private_data,
 270                                          TALLOC_CTX *mem_ctx,
 271                                          const struct auth_usersupplied_info *user_info,
 272                                          struct auth_serversupplied_info **server_info)
 273 {
 274         struct server_security_state *state = NULL;
 275         struct cli_state *cli = NULL;
 276         static bool tested_password_server = False;
 277         static bool bad_password_server = False;
 278         NTSTATUS nt_status = NT_STATUS_NOT_IMPLEMENTED;
 279         bool locally_made_cli = False;
 280         uint16_t sec_mode = 0;
 281
 282         DEBUG(10, ("check_smbserver_security: Check auth for: [%s]\n",
 283                 user_info->mapped.account_name));
 284
 285         if (my_private_data == NULL) {
 286                 DEBUG(10,("check_smbserver_security: "
 287                         "password server is not connected\n"));
 288                 return NT_STATUS_LOGON_FAILURE;
 289         }
 290
 291         state = talloc_get_type_abort(my_private_data, struct server_security_state);
 292         cli = state->cli;
 293
 294         if (cli) {
 295         } else {
 296                 cli = server_cryptkey(mem_ctx);
 297                 locally_made_cli = True;
 298         }
 299
 300         if (!cli_state_is_connected(cli)) {
 301                 DEBUG(1,("password server is not connected (cli not initialised)\n"));
 302                 return NT_STATUS_LOGON_FAILURE;
 303         }
 304
 305         sec_mode = cli_state_security_mode(cli);
 306         if ((sec_mode & NEGOTIATE_SECURITY_CHALLENGE_RESPONSE) == 0) {
 307                 if (user_info->password_state != AUTH_PASSWORD_PLAIN) {
 308                         DEBUG(1,("password server %s is plaintext, but we are encrypted. This just can't work :-(\n", cli_state_remote_name(cli)));
 309                         return NT_STATUS_LOGON_FAILURE;
 310                 }
 311         } else {
 312                 const uint8_t *server_challenge = cli_state_server_challenge(cli);
 313
 314                 if (memcmp(server_challenge, auth_context->challenge.data, 8) != 0) {
 315                         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)));
 316                         return NT_STATUS_LOGON_FAILURE;
 317                 }
 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                 unsigned char badpass[24];
 334                 char *baduser = NULL;
 335
 336                 memset(badpass, 0x1f, sizeof(badpass));
 337
 338                 if((user_info->password.response.nt.length == sizeof(badpass)) &&
 339                    !memcmp(badpass, user_info->password.response.nt.data, sizeof(badpass))) {
 340                         /*
 341                          * Very unlikely, our random bad password is the same as the users
 342                          * password.
 343                          */
 344                         memset(badpass, badpass[0]+1, sizeof(badpass));
 345                 }
 346
 347                 baduser = talloc_asprintf(mem_ctx,
 348                                         "%s%s",
 349                                         INVALID_USER_PREFIX,
 350                                         lp_netbios_name());
 351                 if (!baduser) {
 352                         return NT_STATUS_NO_MEMORY;
 353                 }
 354
 355                 if (NT_STATUS_IS_OK(cli_session_setup(cli, baduser,
 356                                                       (char *)badpass,
 357                                                       sizeof(badpass),
 358                                                       (char *)badpass,
 359                                                       sizeof(badpass),
 360                                                       user_info->mapped.domain_name))) {
 361
 362                         /*
 363                          * We connected to the password server so we
 364                          * can say we've tested it.
 365                          */
 366                         tested_password_server = True;
 367
 368                         if (!cli->is_guestlogin) {
 369                                 DEBUG(0,("server_validate: password server %s allows users as non-guest \
 370 with a bad password.\n", cli_state_remote_name(cli)));
 371                                 DEBUG(0,("server_validate: This is broken (and insecure) behaviour. Please do not \
 372 use this machine as the password server.\n"));
 373                                 cli_ulogoff(cli);
 374
 375                                 /*
 376                                  * Password server has the bug.
 377                                  */
 378                                 bad_password_server = True;
 379                                 return NT_STATUS_LOGON_FAILURE;
 380                         }
 381                         cli_ulogoff(cli);
 382                 }
 383         } else {
 384
 385                 /*
 386                  * We have already tested the password server.
 387                  * Fail immediately if it has the bug.
 388                  */
 389
 390                 if(bad_password_server) {
 391                         DEBUG(0,("server_validate: [1] password server %s allows users as non-guest \
 392 with a bad password.\n", cli_state_remote_name(cli)));
 393                         DEBUG(0,("server_validate: [1] This is broken (and insecure) behaviour. Please do not \
 394 use this machine as the password server.\n"));
 395                         return NT_STATUS_LOGON_FAILURE;
 396                 }
 397         }
 398
 399         /*
 400          * Now we know the password server will correctly set the guest bit, or is
 401          * not guest enabled, we can try with the real password.
 402          */
 403         switch (user_info->password_state) {
 404         case AUTH_PASSWORD_PLAIN:
 405                 /* Plaintext available */
 406                 nt_status = cli_session_setup(
 407                         cli, user_info->client.account_name,
 408                         user_info->password.plaintext,
 409                         strlen(user_info->password.plaintext),
 410                         NULL, 0, user_info->mapped.domain_name);
 411                 break;
 412
 413         /* currently the hash values include a challenge-response as well */
 414         case AUTH_PASSWORD_HASH:
 415         case AUTH_PASSWORD_RESPONSE:
 416                 nt_status = cli_session_setup(
 417                         cli, user_info->client.account_name,
 418                         (char *)user_info->password.response.lanman.data,
 419                         user_info->password.response.lanman.length,
 420                         (char *)user_info->password.response.nt.data,
 421                         user_info->password.response.nt.length,
 422                         user_info->mapped.domain_name);
 423                 break;
 424         default:
 425                 DEBUG(0,("user_info constructed for user '%s' was invalid - password_state=%u invalid.\n",user_info->mapped.account_name, user_info->password_state));
 426                 nt_status = NT_STATUS_INTERNAL_ERROR;
 427         }
 428
 429         if (!NT_STATUS_IS_OK(nt_status)) {
 430                 DEBUG(1,("password server %s rejected the password: %s\n",
 431                          cli_state_remote_name(cli), nt_errstr(nt_status)));
 432         }
 433
 434         /* if logged in as guest then reject */
 435         if (cli->is_guestlogin) {
 436                 DEBUG(1,("password server %s gave us guest only\n",
 437                          cli_state_remote_name(cli)));
 438                 nt_status = NT_STATUS_LOGON_FAILURE;
 439         }
 440
 441         cli_ulogoff(cli);
 442
 443         if (NT_STATUS_IS_OK(nt_status)) {
 444                 char *real_username = NULL;
 445                 struct passwd *pass = NULL;
 446
 447                 if ( (pass = smb_getpwnam(talloc_tos(), user_info->mapped.account_name,
 448                         &real_username, True )) != NULL )
 449                 {
 450                         nt_status = make_server_info_pw(server_info, pass->pw_name, pass);
 451                         TALLOC_FREE(pass);
 452                         TALLOC_FREE(real_username);
 453                 }
 454                 else
 455                 {
 456                         nt_status = NT_STATUS_NO_SUCH_USER;
 457                 }
 458         }
 459
 460         if (locally_made_cli) {
 461                 cli_shutdown(cli);
 462         }
 463
 464         return(nt_status);
 465 }
 466
 467 static NTSTATUS auth_init_smbserver(struct auth_context *auth_context, const char* param, auth_methods **auth_method)
 468 {
 469         struct auth_methods *result;
 470
 471         result = talloc_zero(auth_context, struct auth_methods);
 472         if (result == NULL) {
 473                 return NT_STATUS_NO_MEMORY;
 474         }
 475         result->name = "smbserver";
 476         result->auth = check_smbserver_security;
 477         result->get_chal = auth_get_challenge_server;
 478
 479         *auth_method = result;
 480         return NT_STATUS_OK;
 481 }
 482
 483 NTSTATUS auth_server_init(void)
 484 {
 485         return smb_register_auth(AUTH_INTERFACE_VERSION, "smbserver", auth_init_smbserver);
 486 }