source3/auth/auth_server.c

   1 /*
   2    Unix SMB/Netbios implementation.
   3    Version 1.9.
   4    Authenticate to a remote server
   5    Copyright (C) Andrew Tridgell 1992-1998
   6    Copyright (C) Andrew Bartlett 2001
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 2 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21 */
  22
  23 #include "includes.h"
  24
  25 extern pstring global_myname;
  26 extern userdom_struct current_user_info;
  27
  28 /****************************************************************************
  29  Support for server level security.
  30 ****************************************************************************/
  31
  32 static struct cli_state *server_cryptkey(TALLOC_CTX *mem_ctx)
  33 {
  34         struct cli_state *cli = NULL;
  35         fstring desthost;
  36         struct in_addr dest_ip;
  37         char *p, *pserver;
  38         BOOL connected_ok = False;
  39
  40         if (!(cli = cli_initialise(cli)))
  41                 return NULL;
  42
  43         /* security = server just can't function with spnego */
  44         cli->use_spnego = False;
  45
  46         pserver = talloc_strdup(mem_ctx, lp_passwordserver());
  47         p = pserver;
  48
  49         while(next_token( &p, desthost, LIST_SEP, sizeof(desthost))) {
  50                 standard_sub_basic(current_user_info.smb_name, desthost);
  51                 strupper(desthost);
  52
  53                 if(!resolve_name( desthost, &dest_ip, 0x20)) {
  54                         DEBUG(1,("server_cryptkey: Can't resolve address for %s\n",desthost));
  55                         continue;
  56                 }
  57
  58                 if (ismyip(dest_ip)) {
  59                         DEBUG(1,("Password server loop - disabling password server %s\n",desthost));
  60                         continue;
  61                 }
  62
  63                 if (cli_connect(cli, desthost, &dest_ip)) {
  64                         DEBUG(3,("connected to password server %s\n",desthost));
  65                         connected_ok = True;
  66                         break;
  67                 }
  68         }
  69
  70         if (!connected_ok) {
  71                 DEBUG(0,("password server not available\n"));
  72                 cli_shutdown(cli);
  73                 return NULL;
  74         }
  75
  76         if (!attempt_netbios_session_request(cli, global_myname, desthost, &dest_ip))
  77                 return NULL;
  78
  79         if (strequal(desthost,myhostname())) {
  80                 exit_server("Password server loop!");
  81         }
  82
  83         DEBUG(3,("got session\n"));
  84
  85         if (!cli_negprot(cli)) {
  86                 DEBUG(1,("%s rejected the negprot\n",desthost));
  87                 cli_shutdown(cli);
  88                 return NULL;
  89         }
  90
  91         if (cli->protocol < PROTOCOL_LANMAN2 ||
  92             !(cli->sec_mode & 1)) {
  93                 DEBUG(1,("%s isn't in user level security mode\n",desthost));
  94                 cli_shutdown(cli);
  95                 return NULL;
  96         }
  97
  98         DEBUG(3,("password server OK\n"));
  99
 100         return cli;
 101 }
 102
 103 /****************************************************************************
 104  Clean up our allocated cli.
 105 ****************************************************************************/
 106
 107 static void free_server_private_data(void **private_data_pointer)
 108 {
 109         struct cli_state **cli = (struct cli_state **)private_data_pointer;
 110         if (*cli && (*cli)->initialised) {
 111                 cli_shutdown(*cli);
 112         }
 113 }
 114
 115 /****************************************************************************
 116  Send a 'keepalive' packet down the cli pipe.
 117 ****************************************************************************/
 118
 119 static void send_server_keepalive(void **private_data_pointer)
 120 {
 121         struct cli_state **cli = (struct cli_state **)private_data_pointer;
 122
 123         /* also send a keepalive to the password server if its still
 124            connected */
 125         if (cli && *cli && (*cli)->initialised) {
 126                 if (!send_keepalive((*cli)->fd)) {
 127                         DEBUG( 2, ( "password server keepalive failed.\n"));
 128                         cli_shutdown(*cli);
 129                 }
 130         }
 131 }
 132
 133 /****************************************************************************
 134  Get the challenge out of a password server.
 135 ****************************************************************************/
 136
 137 static DATA_BLOB auth_get_challenge_server(const struct auth_context *auth_context,
 138                                            void **my_private_data,
 139                                            TALLOC_CTX *mem_ctx)
 140 {
 141         struct cli_state *cli = server_cryptkey(mem_ctx);
 142
 143         if (cli) {
 144                 DEBUG(3,("using password server validation\n"));
 145
 146                 if ((cli->sec_mode & 2) == 0) {
 147                         /* We can't work with unencrypted password servers
 148                            unless 'encrypt passwords = no' */
 149                         DEBUG(5,("make_auth_info_server: Server is unencrypted, no challenge available..\n"));
 150
 151                         /* However, it is still a perfectly fine connection
 152                            to pass that unencrypted password over */
 153                         *my_private_data = (void *)cli;
 154                         return data_blob(NULL, 0);
 155
 156                 } else if (cli->secblob.length < 8) {
 157                         /* We can't do much if we don't get a full challenge */
 158                         DEBUG(2,("make_auth_info_server: Didn't receive a full challenge from server\n"));
 159                         cli_shutdown(cli);
 160                         return data_blob(NULL, 0);
 161                 }
 162
 163                 *my_private_data = (void *)cli;
 164
 165                 /* The return must be allocated on the caller's mem_ctx, as our own will be
 166                    destoyed just after the call. */
 167                 return data_blob_talloc(auth_context->mem_ctx, cli->secblob.data,8);
 168         } else {
 169                 return data_blob(NULL, 0);
 170         }
 171 }
 172
 173
 174 /****************************************************************************
 175  Check for a valid username and password in security=server mode.
 176   - Validate a password with the password server.
 177 ****************************************************************************/
 178
 179 static NTSTATUS check_smbserver_security(const struct auth_context *auth_context,
 180                                          void *my_private_data,
 181                                          TALLOC_CTX *mem_ctx,
 182                                          const auth_usersupplied_info *user_info,
 183                                          auth_serversupplied_info **server_info)
 184 {
 185         struct cli_state *cli;
 186         static unsigned char badpass[24];
 187         static fstring baduser;
 188         static BOOL tested_password_server = False;
 189         static BOOL bad_password_server = False;
 190         NTSTATUS nt_status = NT_STATUS_LOGON_FAILURE;
 191         BOOL locally_made_cli = False;
 192
 193         /*
 194          * Check that the requested domain is not our own machine name.
 195          * If it is, we should never check the PDC here, we use our own local
 196          * password file.
 197          */
 198
 199         if(is_netbios_alias_or_name(user_info->domain.str)) {
 200                 DEBUG(3,("check_smbserver_security: Requested domain was for this machine.\n"));
 201                 return NT_STATUS_LOGON_FAILURE;
 202         }
 203
 204         cli = my_private_data;
 205
 206         if (cli) {
 207         } else {
 208                 cli = server_cryptkey(mem_ctx);
 209                 locally_made_cli = True;
 210         }
 211
 212         if (!cli || !cli->initialised) {
 213                 DEBUG(1,("password server is not connected (cli not initilised)\n"));
 214                 return NT_STATUS_LOGON_FAILURE;
 215         }
 216
 217         if ((cli->sec_mode & 2) == 0) {
 218                 if (user_info->encrypted) {
 219                         DEBUG(1,("password server %s is plaintext, but we are encrypted. This just can't work :-(\n", cli->desthost));
 220                         return NT_STATUS_LOGON_FAILURE;
 221                 }
 222         } else {
 223                 if (memcmp(cli->secblob.data, auth_context->challenge.data, 8) != 0) {
 224                         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));
 225                         return NT_STATUS_LOGON_FAILURE;
 226                 }
 227         }
 228
 229         if(badpass[0] == 0)
 230                 memset(badpass, 0x1f, sizeof(badpass));
 231
 232         if((user_info->nt_resp.length == sizeof(badpass)) &&
 233            !memcmp(badpass, user_info->nt_resp.data, sizeof(badpass))) {
 234                 /*
 235                  * Very unlikely, our random bad password is the same as the users
 236                  * password.
 237                  */
 238                 memset(badpass, badpass[0]+1, sizeof(badpass));
 239         }
 240
 241         if(baduser[0] == 0) {
 242                 fstrcpy(baduser, INVALID_USER_PREFIX);
 243                 fstrcat(baduser, global_myname);
 244         }
 245
 246         /*
 247          * Attempt a session setup with a totally incorrect password.
 248          * If this succeeds with the guest bit *NOT* set then the password
 249          * server is broken and is not correctly setting the guest bit. We
 250          * need to detect this as some versions of NT4.x are broken. JRA.
 251          */
 252
 253         /* I sure as hell hope that there arn't servers out there that take
 254          * NTLMv2 and have this bug, as we don't test for that...
 255          *  - abartlet@samba.org
 256          */
 257
 258         if ((!tested_password_server) && (lp_paranoid_server_security())) {
 259                 if (cli_session_setup(cli, baduser, (char *)badpass, sizeof(badpass),
 260                                         (char *)badpass, sizeof(badpass), user_info->domain.str)) {
 261
 262                         /*
 263                          * We connected to the password server so we
 264                          * can say we've tested it.
 265                          */
 266                         tested_password_server = True;
 267
 268                         if ((SVAL(cli->inbuf,smb_vwv2) & 1) == 0) {
 269                                 DEBUG(0,("server_validate: password server %s allows users as non-guest \
 270 with a bad password.\n", cli->desthost));
 271                                 DEBUG(0,("server_validate: This is broken (and insecure) behaviour. Please do not \
 272 use this machine as the password server.\n"));
 273                                 cli_ulogoff(cli);
 274
 275                                 /*
 276                                  * Password server has the bug.
 277                                  */
 278                                 bad_password_server = True;
 279                                 return NT_STATUS_LOGON_FAILURE;
 280                         }
 281                         cli_ulogoff(cli);
 282                 }
 283         } else {
 284
 285                 /*
 286                  * We have already tested the password server.
 287                  * Fail immediately if it has the bug.
 288                  */
 289
 290                 if(bad_password_server) {
 291                         DEBUG(0,("server_validate: [1] password server %s allows users as non-guest \
 292 with a bad password.\n", cli->desthost));
 293                         DEBUG(0,("server_validate: [1] This is broken (and insecure) behaviour. Please do not \
 294 use this machine as the password server.\n"));
 295                         return NT_STATUS_LOGON_FAILURE;
 296                 }
 297         }
 298
 299         /*
 300          * Now we know the password server will correctly set the guest bit, or is
 301          * not guest enabled, we can try with the real password.
 302          */
 303
 304         if (!user_info->encrypted) {
 305                 /* Plaintext available */
 306                 if (!cli_session_setup(cli, user_info->smb_name.str,
 307                                        (char *)user_info->plaintext_password.data,
 308                                        user_info->plaintext_password.length,
 309                                        NULL, 0,
 310                                        user_info->domain.str)) {
 311                         DEBUG(1,("password server %s rejected the password\n", cli->desthost));
 312                         /* Make this cli_nt_error() when the conversion is in */
 313                         nt_status = cli_nt_error(cli);
 314                 } else {
 315                         nt_status = NT_STATUS_OK;
 316                 }
 317         } else {
 318                 if (!cli_session_setup(cli, user_info->smb_name.str,
 319                                        (char *)user_info->lm_resp.data,
 320                                        user_info->lm_resp.length,
 321                                        (char *)user_info->nt_resp.data,
 322                                        user_info->nt_resp.length,
 323                                        user_info->domain.str)) {
 324                         DEBUG(1,("password server %s rejected the password\n", cli->desthost));
 325                         /* Make this cli_nt_error() when the conversion is in */
 326                         nt_status = cli_nt_error(cli);
 327                 } else {
 328                         nt_status = NT_STATUS_OK;
 329                 }
 330         }
 331
 332         /* if logged in as guest then reject */
 333         if ((SVAL(cli->inbuf,smb_vwv2) & 1) != 0) {
 334                 DEBUG(1,("password server %s gave us guest only\n", cli->desthost));
 335                 nt_status = NT_STATUS_LOGON_FAILURE;
 336         }
 337
 338         cli_ulogoff(cli);
 339
 340         if NT_STATUS_IS_OK(nt_status) {
 341                 struct passwd *pass = Get_Pwnam(user_info->internal_username.str);
 342                 if (pass) {
 343                         if (!make_server_info_pw(server_info, pass)) {
 344                                 nt_status = NT_STATUS_NO_MEMORY;
 345                         }
 346                 } else {
 347                         nt_status = NT_STATUS_NO_SUCH_USER;
 348                 }
 349         }
 350
 351         if (locally_made_cli) {
 352                 cli_shutdown(cli);
 353         }
 354
 355         return(nt_status);
 356 }
 357
 358 BOOL auth_init_smbserver(struct auth_context *auth_context, auth_methods **auth_method)
 359 {
 360         if (!make_auth_methods(auth_context, auth_method)) {
 361                 return False;
 362         }
 363         (*auth_method)->auth = check_smbserver_security;
 364         (*auth_method)->get_chal = auth_get_challenge_server;
 365         (*auth_method)->send_keepalive = send_server_keepalive;
 366         (*auth_method)->free_private_data = free_server_private_data;
 367         return True;
 368 }