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