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 DGBC_AUTH
  26
  27 extern pstring global_myname;
  28 extern userdom_struct current_user_info;
  29
  30 /****************************************************************************
  31  Support for server level security.
  32 ****************************************************************************/
  33
  34 static struct cli_state *server_cryptkey(TALLOC_CTX *mem_ctx)
  35 {
  36         struct cli_state *cli = NULL;
  37         fstring desthost;
  38         struct in_addr dest_ip;
  39         char *p, *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);
  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                 if (cli_connect(cli, desthost, &dest_ip)) {
  66                         DEBUG(3,("connected to password server %s\n",desthost));
  67                         connected_ok = True;
  68                         break;
  69                 }
  70         }
  71
  72         if (!connected_ok) {
  73                 DEBUG(0,("password server not available\n"));
  74                 cli_shutdown(cli);
  75                 return NULL;
  76         }
  77
  78         if (!attempt_netbios_session_request(cli, global_myname, desthost, &dest_ip))
  79                 return NULL;
  80
  81         if (strequal(desthost,myhostname())) {
  82                 exit_server("Password server loop!");
  83         }
  84
  85         DEBUG(3,("got session\n"));
  86
  87         if (!cli_negprot(cli)) {
  88                 DEBUG(1,("%s rejected the negprot\n",desthost));
  89                 cli_shutdown(cli);
  90                 return NULL;
  91         }
  92
  93         if (cli->protocol < PROTOCOL_LANMAN2 ||
  94             !(cli->sec_mode & 1)) {
  95                 DEBUG(1,("%s isn't in user level security mode\n",desthost));
  96                 cli_shutdown(cli);
  97                 return NULL;
  98         }
  99
 100         DEBUG(3,("password server OK\n"));
 101
 102         return cli;
 103 }
 104
 105 /****************************************************************************
 106  Clean up our allocated cli.
 107 ****************************************************************************/
 108
 109 static void free_server_private_data(void **private_data_pointer)
 110 {
 111         struct cli_state **cli = (struct cli_state **)private_data_pointer;
 112         if (*cli && (*cli)->initialised) {
 113                 cli_shutdown(*cli);
 114         }
 115 }
 116
 117 /****************************************************************************
 118  Send a 'keepalive' packet down the cli pipe.
 119 ****************************************************************************/
 120
 121 static void send_server_keepalive(void **private_data_pointer)
 122 {
 123         struct cli_state **cli = (struct cli_state **)private_data_pointer;
 124
 125         /* also send a keepalive to the password server if its still
 126            connected */
 127         if (cli && *cli && (*cli)->initialised) {
 128                 if (!send_keepalive((*cli)->fd)) {
 129                         DEBUG( 2, ( "password server keepalive failed.\n"));
 130                         cli_shutdown(*cli);
 131                 }
 132         }
 133 }
 134
 135 /****************************************************************************
 136  Get the challenge out of a password server.
 137 ****************************************************************************/
 138
 139 static DATA_BLOB auth_get_challenge_server(const struct auth_context *auth_context,
 140                                            void **my_private_data,
 141                                            TALLOC_CTX *mem_ctx)
 142 {
 143         struct cli_state *cli = server_cryptkey(mem_ctx);
 144
 145         if (cli) {
 146                 DEBUG(3,("using password server validation\n"));
 147
 148                 if ((cli->sec_mode & 2) == 0) {
 149                         /* We can't work with unencrypted password servers
 150                            unless 'encrypt passwords = no' */
 151                         DEBUG(5,("make_auth_info_server: Server is unencrypted, no challenge available..\n"));
 152
 153                         /* However, it is still a perfectly fine connection
 154                            to pass that unencrypted password over */
 155                         *my_private_data = (void *)cli;
 156                         return data_blob(NULL, 0);
 157
 158                 } else if (cli->secblob.length < 8) {
 159                         /* We can't do much if we don't get a full challenge */
 160                         DEBUG(2,("make_auth_info_server: Didn't receive a full challenge from server\n"));
 161                         cli_shutdown(cli);
 162                         return data_blob(NULL, 0);
 163                 }
 164
 165                 *my_private_data = (void *)cli;
 166
 167                 /* The return must be allocated on the caller's mem_ctx, as our own will be
 168                    destoyed just after the call. */
 169                 return data_blob_talloc(auth_context->mem_ctx, cli->secblob.data,8);
 170         } else {
 171                 return data_blob(NULL, 0);
 172         }
 173 }
 174
 175
 176 /****************************************************************************
 177  Check for a valid username and password in security=server mode.
 178   - Validate a password with the password server.
 179 ****************************************************************************/
 180
 181 static NTSTATUS check_smbserver_security(const struct auth_context *auth_context,
 182                                          void *my_private_data,
 183                                          TALLOC_CTX *mem_ctx,
 184                                          const auth_usersupplied_info *user_info,
 185                                          auth_serversupplied_info **server_info)
 186 {
 187         struct cli_state *cli;
 188         static unsigned char badpass[24];
 189         static fstring baduser;
 190         static BOOL tested_password_server = False;
 191         static BOOL bad_password_server = False;
 192         NTSTATUS nt_status = NT_STATUS_LOGON_FAILURE;
 193         BOOL locally_made_cli = False;
 194
 195         /*
 196          * Check that the requested domain is not our own machine name.
 197          * If it is, we should never check the PDC here, we use our own local
 198          * password file.
 199          */
 200
 201         if(is_netbios_alias_or_name(user_info->domain.str)) {
 202                 DEBUG(3,("check_smbserver_security: Requested domain was for this machine.\n"));
 203                 return NT_STATUS_LOGON_FAILURE;
 204         }
 205
 206         cli = my_private_data;
 207
 208         if (cli) {
 209         } else {
 210                 cli = server_cryptkey(mem_ctx);
 211                 locally_made_cli = True;
 212         }
 213
 214         if (!cli || !cli->initialised) {
 215                 DEBUG(1,("password server is not connected (cli not initilised)\n"));
 216                 return NT_STATUS_LOGON_FAILURE;
 217         }
 218
 219         if ((cli->sec_mode & 2) == 0) {
 220                 if (user_info->encrypted) {
 221                         DEBUG(1,("password server %s is plaintext, but we are encrypted. This just can't work :-(\n", cli->desthost));
 222                         return NT_STATUS_LOGON_FAILURE;
 223                 }
 224         } else {
 225                 if (memcmp(cli->secblob.data, auth_context->challenge.data, 8) != 0) {
 226                         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));
 227                         return NT_STATUS_LOGON_FAILURE;
 228                 }
 229         }
 230
 231         if(badpass[0] == 0)
 232                 memset(badpass, 0x1f, sizeof(badpass));
 233
 234         if((user_info->nt_resp.length == sizeof(badpass)) &&
 235            !memcmp(badpass, user_info->nt_resp.data, sizeof(badpass))) {
 236                 /*
 237                  * Very unlikely, our random bad password is the same as the users
 238                  * password.
 239                  */
 240                 memset(badpass, badpass[0]+1, sizeof(badpass));
 241         }
 242
 243         if(baduser[0] == 0) {
 244                 fstrcpy(baduser, INVALID_USER_PREFIX);
 245                 fstrcat(baduser, global_myname);
 246         }
 247
 248         /*
 249          * Attempt a session setup with a totally incorrect password.
 250          * If this succeeds with the guest bit *NOT* set then the password
 251          * server is broken and is not correctly setting the guest bit. We
 252          * need to detect this as some versions of NT4.x are broken. JRA.
 253          */
 254
 255         /* I sure as hell hope that there arn't servers out there that take
 256          * NTLMv2 and have this bug, as we don't test for that...
 257          *  - abartlet@samba.org
 258          */
 259
 260         if ((!tested_password_server) && (lp_paranoid_server_security())) {
 261                 if (cli_session_setup(cli, baduser, (char *)badpass, sizeof(badpass),
 262                                         (char *)badpass, sizeof(badpass), user_info->domain.str)) {
 263
 264                         /*
 265                          * We connected to the password server so we
 266                          * can say we've tested it.
 267                          */
 268                         tested_password_server = True;
 269
 270                         if ((SVAL(cli->inbuf,smb_vwv2) & 1) == 0) {
 271                                 DEBUG(0,("server_validate: password server %s allows users as non-guest \
 272 with a bad password.\n", cli->desthost));
 273                                 DEBUG(0,("server_validate: This is broken (and insecure) behaviour. Please do not \
 274 use this machine as the password server.\n"));
 275                                 cli_ulogoff(cli);
 276
 277                                 /*
 278                                  * Password server has the bug.
 279                                  */
 280                                 bad_password_server = True;
 281                                 return NT_STATUS_LOGON_FAILURE;
 282                         }
 283                         cli_ulogoff(cli);
 284                 }
 285         } else {
 286
 287                 /*
 288                  * We have already tested the password server.
 289                  * Fail immediately if it has the bug.
 290                  */
 291
 292                 if(bad_password_server) {
 293                         DEBUG(0,("server_validate: [1] password server %s allows users as non-guest \
 294 with a bad password.\n", cli->desthost));
 295                         DEBUG(0,("server_validate: [1] This is broken (and insecure) behaviour. Please do not \
 296 use this machine as the password server.\n"));
 297                         return NT_STATUS_LOGON_FAILURE;
 298                 }
 299         }
 300
 301         /*
 302          * Now we know the password server will correctly set the guest bit, or is
 303          * not guest enabled, we can try with the real password.
 304          */
 305
 306         if (!user_info->encrypted) {
 307                 /* Plaintext available */
 308                 if (!cli_session_setup(cli, user_info->smb_name.str,
 309                                        (char *)user_info->plaintext_password.data,
 310                                        user_info->plaintext_password.length,
 311                                        NULL, 0,
 312                                        user_info->domain.str)) {
 313                         DEBUG(1,("password server %s rejected the password\n", cli->desthost));
 314                         /* Make this cli_nt_error() when the conversion is in */
 315                         nt_status = cli_nt_error(cli);
 316                 } else {
 317                         nt_status = NT_STATUS_OK;
 318                 }
 319         } else {
 320                 if (!cli_session_setup(cli, user_info->smb_name.str,
 321                                        (char *)user_info->lm_resp.data,
 322                                        user_info->lm_resp.length,
 323                                        (char *)user_info->nt_resp.data,
 324                                        user_info->nt_resp.length,
 325                                        user_info->domain.str)) {
 326                         DEBUG(1,("password server %s rejected the password\n", cli->desthost));
 327                         /* Make this cli_nt_error() when the conversion is in */
 328                         nt_status = cli_nt_error(cli);
 329                 } else {
 330                         nt_status = NT_STATUS_OK;
 331                 }
 332         }
 333
 334         /* if logged in as guest then reject */
 335         if ((SVAL(cli->inbuf,smb_vwv2) & 1) != 0) {
 336                 DEBUG(1,("password server %s gave us guest only\n", cli->desthost));
 337                 nt_status = NT_STATUS_LOGON_FAILURE;
 338         }
 339
 340         cli_ulogoff(cli);
 341
 342         if NT_STATUS_IS_OK(nt_status) {
 343                 struct passwd *pass = Get_Pwnam(user_info->internal_username.str);
 344                 if (pass) {
 345                         if (!make_server_info_pw(server_info, pass)) {
 346                                 nt_status = NT_STATUS_NO_MEMORY;
 347                         }
 348                 } else {
 349                         nt_status = NT_STATUS_NO_SUCH_USER;
 350                 }
 351         }
 352
 353         if (locally_made_cli) {
 354                 cli_shutdown(cli);
 355         }
 356
 357         return(nt_status);
 358 }
 359
 360 BOOL auth_init_smbserver(struct auth_context *auth_context, auth_methods **auth_method)
 361 {
 362         if (!make_auth_methods(auth_context, auth_method)) {
 363                 return False;
 364         }
 365         (*auth_method)->auth = check_smbserver_security;
 366         (*auth_method)->get_chal = auth_get_challenge_server;
 367         (*auth_method)->send_keepalive = send_server_keepalive;
 368         (*auth_method)->free_private_data = free_server_private_data;
 369         return True;
 370 }