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