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