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