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 /****************************************************************************
 140  Clean up our allocated cli.
 141 ****************************************************************************/
 142
 143 static void free_server_private_data(void **private_data_pointer)
 144 {
 145         struct cli_state **cli = (struct cli_state **)private_data_pointer;
 146         if (*cli && (*cli)->initialised) {
 147                 DEBUG(10, ("Shutting down smbserver connection\n"));
 148                 cli_shutdown(*cli);
 149         }
 150         *private_data_pointer = NULL;
 151 }
 152
 153 /****************************************************************************
 154  Send a 'keepalive' packet down the cli pipe.
 155 ****************************************************************************/
 156
 157 static void send_server_keepalive(void **private_data_pointer)
 158 {
 159         /* also send a keepalive to the password server if its still
 160            connected */
 161         if (private_data_pointer) {
 162                 struct cli_state *cli = (struct cli_state *)(*private_data_pointer);
 163                 if (cli && cli->initialised) {
 164                         if (!send_keepalive(cli->fd)) {
 165                                 DEBUG( 2, ( "send_server_keepalive: password server keepalive failed.\n"));
 166                                 cli_shutdown(cli);
 167                                 *private_data_pointer = NULL;
 168                         }
 169                 }
 170         }
 171 }
 172
 173 /****************************************************************************
 174  Get the challenge out of a password server.
 175 ****************************************************************************/
 176
 177 static DATA_BLOB auth_get_challenge_server(const struct auth_context *auth_context,
 178                                            void **my_private_data,
 179                                            TALLOC_CTX *mem_ctx)
 180 {
 181         struct cli_state *cli = server_cryptkey(mem_ctx);
 182
 183         if (cli) {
 184                 DEBUG(3,("using password server validation\n"));
 185
 186                 if ((cli->sec_mode & NEGOTIATE_SECURITY_CHALLENGE_RESPONSE) == 0) {
 187                         /* We can't work with unencrypted password servers
 188                            unless 'encrypt passwords = no' */
 189                         DEBUG(5,("make_auth_info_server: Server is unencrypted, no challenge available..\n"));
 190
 191                         /* However, it is still a perfectly fine connection
 192                            to pass that unencrypted password over */
 193                         *my_private_data = (void *)cli;
 194                         return data_blob(NULL, 0);
 195
 196                 } else if (cli->secblob.length < 8) {
 197                         /* We can't do much if we don't get a full challenge */
 198                         DEBUG(2,("make_auth_info_server: Didn't receive a full challenge from server\n"));
 199                         cli_shutdown(cli);
 200                         return data_blob(NULL, 0);
 201                 }
 202
 203                 *my_private_data = (void *)cli;
 204
 205                 /* The return must be allocated on the caller's mem_ctx, as our own will be
 206                    destoyed just after the call. */
 207                 return data_blob_talloc(auth_context->mem_ctx, cli->secblob.data,8);
 208         } else {
 209                 return data_blob(NULL, 0);
 210         }
 211 }
 212
 213
 214 /****************************************************************************
 215  Check for a valid username and password in security=server mode.
 216   - Validate a password with the password server.
 217 ****************************************************************************/
 218
 219 static NTSTATUS check_smbserver_security(const struct auth_context *auth_context,
 220                                          void *my_private_data,
 221                                          TALLOC_CTX *mem_ctx,
 222                                          const auth_usersupplied_info *user_info,
 223                                          auth_serversupplied_info **server_info)
 224 {
 225         struct cli_state *cli;
 226         static unsigned char badpass[24];
 227         static fstring baduser;
 228         static BOOL tested_password_server = False;
 229         static BOOL bad_password_server = False;
 230         NTSTATUS nt_status = NT_STATUS_NOT_IMPLEMENTED;
 231         BOOL locally_made_cli = False;
 232
 233         /*
 234          * Check that the requested domain is not our own machine name.
 235          * If it is, we should never check the PDC here, we use our own local
 236          * password file.
 237          */
 238
 239         if(is_myname(user_info->domain)) {
 240                 DEBUG(3,("check_smbserver_security: Requested domain was for this machine.\n"));
 241                 return nt_status;
 242         }
 243
 244         cli = (struct cli_state *)my_private_data;
 245
 246         if (cli) {
 247         } else {
 248                 cli = server_cryptkey(mem_ctx);
 249                 locally_made_cli = True;
 250         }
 251
 252         if (!cli || !cli->initialised) {
 253                 DEBUG(1,("password server is not connected (cli not initilised)\n"));
 254                 return NT_STATUS_LOGON_FAILURE;
 255         }
 256
 257         if ((cli->sec_mode & NEGOTIATE_SECURITY_CHALLENGE_RESPONSE) == 0) {
 258                 if (user_info->encrypted) {
 259                         DEBUG(1,("password server %s is plaintext, but we are encrypted. This just can't work :-(\n", cli->desthost));
 260                         return NT_STATUS_LOGON_FAILURE;
 261                 }
 262         } else {
 263                 if (memcmp(cli->secblob.data, auth_context->challenge.data, 8) != 0) {
 264                         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));
 265                         return NT_STATUS_LOGON_FAILURE;
 266                 }
 267         }
 268
 269         if(badpass[0] == 0)
 270                 memset(badpass, 0x1f, sizeof(badpass));
 271
 272         if((user_info->nt_resp.length == sizeof(badpass)) &&
 273            !memcmp(badpass, user_info->nt_resp.data, sizeof(badpass))) {
 274                 /*
 275                  * Very unlikely, our random bad password is the same as the users
 276                  * password.
 277                  */
 278                 memset(badpass, badpass[0]+1, sizeof(badpass));
 279         }
 280
 281         if(baduser[0] == 0) {
 282                 fstrcpy(baduser, INVALID_USER_PREFIX);
 283                 fstrcat(baduser, global_myname());
 284         }
 285
 286         /*
 287          * Attempt a session setup with a totally incorrect password.
 288          * If this succeeds with the guest bit *NOT* set then the password
 289          * server is broken and is not correctly setting the guest bit. We
 290          * need to detect this as some versions of NT4.x are broken. JRA.
 291          */
 292
 293         /* I sure as hell hope that there aren't servers out there that take
 294          * NTLMv2 and have this bug, as we don't test for that...
 295          *  - abartlet@samba.org
 296          */
 297
 298         if ((!tested_password_server) && (lp_paranoid_server_security())) {
 299                 if (NT_STATUS_IS_OK(cli_session_setup(cli, baduser,
 300                                                       (char *)badpass,
 301                                                       sizeof(badpass),
 302                                                       (char *)badpass,
 303                                                       sizeof(badpass),
 304                                                       user_info->domain))) {
 305
 306                         /*
 307                          * We connected to the password server so we
 308                          * can say we've tested it.
 309                          */
 310                         tested_password_server = True;
 311
 312                         if ((SVAL(cli->inbuf,smb_vwv2) & 1) == 0) {
 313                                 DEBUG(0,("server_validate: password server %s allows users as non-guest \
 314 with a bad password.\n", cli->desthost));
 315                                 DEBUG(0,("server_validate: This is broken (and insecure) behaviour. Please do not \
 316 use this machine as the password server.\n"));
 317                                 cli_ulogoff(cli);
 318
 319                                 /*
 320                                  * Password server has the bug.
 321                                  */
 322                                 bad_password_server = True;
 323                                 return NT_STATUS_LOGON_FAILURE;
 324                         }
 325                         cli_ulogoff(cli);
 326                 }
 327         } else {
 328
 329                 /*
 330                  * We have already tested the password server.
 331                  * Fail immediately if it has the bug.
 332                  */
 333
 334                 if(bad_password_server) {
 335                         DEBUG(0,("server_validate: [1] password server %s allows users as non-guest \
 336 with a bad password.\n", cli->desthost));
 337                         DEBUG(0,("server_validate: [1] This is broken (and insecure) behaviour. Please do not \
 338 use this machine as the password server.\n"));
 339                         return NT_STATUS_LOGON_FAILURE;
 340                 }
 341         }
 342
 343         /*
 344          * Now we know the password server will correctly set the guest bit, or is
 345          * not guest enabled, we can try with the real password.
 346          */
 347
 348         if (!user_info->encrypted) {
 349                 /* Plaintext available */
 350                 nt_status = cli_session_setup(
 351                         cli, user_info->smb_name,
 352                         (char *)user_info->plaintext_password.data,
 353                         user_info->plaintext_password.length,
 354                         NULL, 0, user_info->domain);
 355
 356         } else {
 357                 nt_status = cli_session_setup(
 358                         cli, user_info->smb_name,
 359                         (char *)user_info->lm_resp.data,
 360                         user_info->lm_resp.length,
 361                         (char *)user_info->nt_resp.data,
 362                         user_info->nt_resp.length,
 363                         user_info->domain);
 364         }
 365
 366         if (!NT_STATUS_IS_OK(nt_status)) {
 367                 DEBUG(1,("password server %s rejected the password: %s\n",
 368                          cli->desthost, nt_errstr(nt_status)));
 369         }
 370
 371         /* if logged in as guest then reject */
 372         if ((SVAL(cli->inbuf,smb_vwv2) & 1) != 0) {
 373                 DEBUG(1,("password server %s gave us guest only\n", cli->desthost));
 374                 nt_status = NT_STATUS_LOGON_FAILURE;
 375         }
 376
 377         cli_ulogoff(cli);
 378
 379         if (NT_STATUS_IS_OK(nt_status)) {
 380                 fstring real_username;
 381                 struct passwd *pass;
 382
 383                 if ( (pass = smb_getpwnam( NULL, user_info->internal_username,
 384                         real_username, True )) != NULL )
 385                 {
 386                         /* if a real user check pam account restrictions */
 387                         /* only really perfomed if "obey pam restriction" is true */
 388                         nt_status = smb_pam_accountcheck(pass->pw_name);
 389                         if (  !NT_STATUS_IS_OK(nt_status)) {
 390                                 DEBUG(1, ("PAM account restriction prevents user login\n"));
 391                         } else {
 392
 393                                 nt_status = make_server_info_pw(server_info, pass->pw_name, pass);
 394                         }
 395                         TALLOC_FREE(pass);
 396                 }
 397                 else
 398                 {
 399                         nt_status = NT_STATUS_NO_SUCH_USER;
 400                 }
 401         }
 402
 403         if (locally_made_cli) {
 404                 cli_shutdown(cli);
 405         }
 406
 407         return(nt_status);
 408 }
 409
 410 static NTSTATUS auth_init_smbserver(struct auth_context *auth_context, const char* param, auth_methods **auth_method)
 411 {
 412         if (!make_auth_methods(auth_context, auth_method)) {
 413                 return NT_STATUS_NO_MEMORY;
 414         }
 415         (*auth_method)->name = "smbserver";
 416         (*auth_method)->auth = check_smbserver_security;
 417         (*auth_method)->get_chal = auth_get_challenge_server;
 418         (*auth_method)->send_keepalive = send_server_keepalive;
 419         (*auth_method)->free_private_data = free_server_private_data;
 420         return NT_STATUS_OK;
 421 }
 422
 423 NTSTATUS auth_server_init(void)
 424 {
 425         return smb_register_auth(AUTH_INTERFACE_VERSION, "smbserver", auth_init_smbserver);
 426 }