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                 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         cli = (struct cli_state *)my_private_data;
 234
 235         if (cli) {
 236         } else {
 237                 cli = server_cryptkey(mem_ctx);
 238                 locally_made_cli = True;
 239         }
 240
 241         if (!cli || !cli->initialised) {
 242                 DEBUG(1,("password server is not connected (cli not initilised)\n"));
 243                 return NT_STATUS_LOGON_FAILURE;
 244         }
 245
 246         if ((cli->sec_mode & NEGOTIATE_SECURITY_CHALLENGE_RESPONSE) == 0) {
 247                 if (user_info->encrypted) {
 248                         DEBUG(1,("password server %s is plaintext, but we are encrypted. This just can't work :-(\n", cli->desthost));
 249                         return NT_STATUS_LOGON_FAILURE;
 250                 }
 251         } else {
 252                 if (memcmp(cli->secblob.data, auth_context->challenge.data, 8) != 0) {
 253                         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));
 254                         return NT_STATUS_LOGON_FAILURE;
 255                 }
 256         }
 257
 258         if(badpass[0] == 0)
 259                 memset(badpass, 0x1f, sizeof(badpass));
 260
 261         if((user_info->nt_resp.length == sizeof(badpass)) &&
 262            !memcmp(badpass, user_info->nt_resp.data, sizeof(badpass))) {
 263                 /*
 264                  * Very unlikely, our random bad password is the same as the users
 265                  * password.
 266                  */
 267                 memset(badpass, badpass[0]+1, sizeof(badpass));
 268         }
 269
 270         if(baduser[0] == 0) {
 271                 fstrcpy(baduser, INVALID_USER_PREFIX);
 272                 fstrcat(baduser, global_myname());
 273         }
 274
 275         /*
 276          * Attempt a session setup with a totally incorrect password.
 277          * If this succeeds with the guest bit *NOT* set then the password
 278          * server is broken and is not correctly setting the guest bit. We
 279          * need to detect this as some versions of NT4.x are broken. JRA.
 280          */
 281
 282         /* I sure as hell hope that there aren't servers out there that take
 283          * NTLMv2 and have this bug, as we don't test for that...
 284          *  - abartlet@samba.org
 285          */
 286
 287         if ((!tested_password_server) && (lp_paranoid_server_security())) {
 288                 if (NT_STATUS_IS_OK(cli_session_setup(cli, baduser,
 289                                                       (char *)badpass,
 290                                                       sizeof(badpass),
 291                                                       (char *)badpass,
 292                                                       sizeof(badpass),
 293                                                       user_info->domain))) {
 294
 295                         /*
 296                          * We connected to the password server so we
 297                          * can say we've tested it.
 298                          */
 299                         tested_password_server = True;
 300
 301                         if ((SVAL(cli->inbuf,smb_vwv2) & 1) == 0) {
 302                                 DEBUG(0,("server_validate: password server %s allows users as non-guest \
 303 with a bad password.\n", cli->desthost));
 304                                 DEBUG(0,("server_validate: This is broken (and insecure) behaviour. Please do not \
 305 use this machine as the password server.\n"));
 306                                 cli_ulogoff(cli);
 307
 308                                 /*
 309                                  * Password server has the bug.
 310                                  */
 311                                 bad_password_server = True;
 312                                 return NT_STATUS_LOGON_FAILURE;
 313                         }
 314                         cli_ulogoff(cli);
 315                 }
 316         } else {
 317
 318                 /*
 319                  * We have already tested the password server.
 320                  * Fail immediately if it has the bug.
 321                  */
 322
 323                 if(bad_password_server) {
 324                         DEBUG(0,("server_validate: [1] password server %s allows users as non-guest \
 325 with a bad password.\n", cli->desthost));
 326                         DEBUG(0,("server_validate: [1] This is broken (and insecure) behaviour. Please do not \
 327 use this machine as the password server.\n"));
 328                         return NT_STATUS_LOGON_FAILURE;
 329                 }
 330         }
 331
 332         /*
 333          * Now we know the password server will correctly set the guest bit, or is
 334          * not guest enabled, we can try with the real password.
 335          */
 336
 337         if (!user_info->encrypted) {
 338                 /* Plaintext available */
 339                 nt_status = cli_session_setup(
 340                         cli, user_info->smb_name,
 341                         (char *)user_info->plaintext_password.data,
 342                         user_info->plaintext_password.length,
 343                         NULL, 0, user_info->domain);
 344
 345         } else {
 346                 nt_status = cli_session_setup(
 347                         cli, user_info->smb_name,
 348                         (char *)user_info->lm_resp.data,
 349                         user_info->lm_resp.length,
 350                         (char *)user_info->nt_resp.data,
 351                         user_info->nt_resp.length,
 352                         user_info->domain);
 353         }
 354
 355         if (!NT_STATUS_IS_OK(nt_status)) {
 356                 DEBUG(1,("password server %s rejected the password: %s\n",
 357                          cli->desthost, nt_errstr(nt_status)));
 358         }
 359
 360         /* if logged in as guest then reject */
 361         if ((SVAL(cli->inbuf,smb_vwv2) & 1) != 0) {
 362                 DEBUG(1,("password server %s gave us guest only\n", cli->desthost));
 363                 nt_status = NT_STATUS_LOGON_FAILURE;
 364         }
 365
 366         cli_ulogoff(cli);
 367
 368         if (NT_STATUS_IS_OK(nt_status)) {
 369                 fstring real_username;
 370                 struct passwd *pass;
 371
 372                 if ( (pass = smb_getpwnam( NULL, user_info->internal_username,
 373                         real_username, True )) != NULL )
 374                 {
 375                         /* if a real user check pam account restrictions */
 376                         /* only really perfomed if "obey pam restriction" is true */
 377                         nt_status = smb_pam_accountcheck(pass->pw_name);
 378                         if (  !NT_STATUS_IS_OK(nt_status)) {
 379                                 DEBUG(1, ("PAM account restriction prevents user login\n"));
 380                         } else {
 381
 382                                 nt_status = make_server_info_pw(server_info, pass->pw_name, pass);
 383                         }
 384                         TALLOC_FREE(pass);
 385                 }
 386                 else
 387                 {
 388                         nt_status = NT_STATUS_NO_SUCH_USER;
 389                 }
 390         }
 391
 392         if (locally_made_cli) {
 393                 cli_shutdown(cli);
 394         }
 395
 396         return(nt_status);
 397 }
 398
 399 static NTSTATUS auth_init_smbserver(struct auth_context *auth_context, const char* param, auth_methods **auth_method)
 400 {
 401         if (!make_auth_methods(auth_context, auth_method)) {
 402                 return NT_STATUS_NO_MEMORY;
 403         }
 404         (*auth_method)->name = "smbserver";
 405         (*auth_method)->auth = check_smbserver_security;
 406         (*auth_method)->get_chal = auth_get_challenge_server;
 407         (*auth_method)->send_keepalive = send_server_keepalive;
 408         (*auth_method)->free_private_data = free_server_private_data;
 409         return NT_STATUS_OK;
 410 }
 411
 412 NTSTATUS auth_server_init(void)
 413 {
 414         return smb_register_auth(AUTH_INTERFACE_VERSION, "smbserver", auth_init_smbserver);
 415 }