source3/pam_smbpass/pam_smb_passwd.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Use PAM to update user passwords in the local SAM
   4    Copyright (C) Steve Langasek         1998-2003
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18
  19 */
  20
  21 /* indicate the following groups are defined */
  22 #define PAM_SM_PASSWORD
  23
  24 #include "includes.h"
  25
  26 /* This is only used in the Sun implementation.  FIXME: we really
  27    want a define here that distinguishes between the Solaris PAM
  28    and others (including FreeBSD). */
  29
  30 #ifndef LINUX
  31 #if defined(HAVE_SECURITY_PAM_APPL_H)
  32 #include <security/pam_appl.h>
  33 #elif defined(HAVE_PAM_PAM_APPL_H)
  34 #include <pam/pam_appl.h>
  35 #endif
  36 #endif
  37
  38 #if defined(HAVE_SECURITY_PAM_MODULES_H)
  39 #include <security/pam_modules.h>
  40 #elif defined(HAVE_PAM_PAM_MODULES_H)
  41 #include <pam/pam_modules.h>
  42 #endif
  43
  44 #include "general.h"
  45
  46 #include "support.h"
  47
  48 int smb_update_db( pam_handle_t *pamh, int ctrl, const char *user,  const char *pass_new )
  49 {
  50         int retval;
  51         char *err_str = NULL;
  52         char *msg_str = NULL;
  53
  54         retval = NT_STATUS_IS_OK(local_password_change(user, LOCAL_SET_PASSWORD, pass_new,
  55                                         &err_str,
  56                                         &msg_str));
  57
  58         if (!retval) {
  59                 if (err_str) {
  60                         make_remark(pamh, ctrl, PAM_ERROR_MSG, err_str );
  61                 }
  62
  63                 /* FIXME: what value is appropriate here? */
  64                 retval = PAM_AUTHTOK_ERR;
  65         } else {
  66                 if (msg_str) {
  67                         make_remark(pamh, ctrl, PAM_TEXT_INFO, msg_str );
  68                 }
  69                 retval = PAM_SUCCESS;
  70         }
  71
  72         SAFE_FREE(err_str);
  73         SAFE_FREE(msg_str);
  74         return retval;
  75 }
  76
  77
  78 /* data tokens */
  79
  80 #define _SMB_OLD_AUTHTOK  "-SMB-OLD-PASS"
  81 #define _SMB_NEW_AUTHTOK  "-SMB-NEW-PASS"
  82
  83 /*
  84  * FUNCTION: pam_sm_chauthtok()
  85  *
  86  * This function is called twice by the PAM library, once with
  87  * PAM_PRELIM_CHECK set, and then again with PAM_UPDATE_AUTHTOK set.  With
  88  * Linux-PAM, these two passes generally involve first checking the old
  89  * token and then changing the token.  This is what we do here.
  90  *
  91  * Having obtained a new password. The function updates the
  92  * SMB_PASSWD_FILE file (normally, $(LIBDIR)/smbpasswd).
  93  */
  94
  95 int pam_sm_chauthtok(pam_handle_t *pamh, int flags,
  96                      int argc, const char **argv)
  97 {
  98     unsigned int ctrl;
  99     int retval;
 100
 101     extern bool in_client;
 102
 103     struct samu *sampass = NULL;
 104     void (*oldsig_handler)(int);
 105     const char *user;
 106     char *pass_old;
 107     char *pass_new;
 108
 109     /* Samba initialization. */
 110     load_case_tables();
 111     setup_logging( "pam_smbpass", False );
 112     in_client = True;
 113
 114     ctrl = set_ctrl(flags, argc, argv);
 115
 116     /*
 117      * First get the name of a user.  No need to do anything if we can't
 118      * determine this.
 119      */
 120
 121     retval = pam_get_user( pamh, &user, "Username: " );
 122     if (retval != PAM_SUCCESS) {
 123         if (on( SMB_DEBUG, ctrl )) {
 124             _log_err( LOG_DEBUG, "password: could not identify user" );
 125         }
 126         return retval;
 127     }
 128     if (on( SMB_DEBUG, ctrl )) {
 129         _log_err( LOG_DEBUG, "username [%s] obtained", user );
 130     }
 131
 132     if (geteuid() != 0) {
 133         _log_err( LOG_DEBUG, "Cannot access samba password database, not running as root.");
 134         return PAM_AUTHINFO_UNAVAIL;
 135     }
 136
 137     /* Getting into places that might use LDAP -- protect the app
 138        from a SIGPIPE it's not expecting */
 139     oldsig_handler = CatchSignal(SIGPIPE, SIGNAL_CAST SIG_IGN);
 140
 141     if (!initialize_password_db(False, NULL)) {
 142         _log_err( LOG_ALERT, "Cannot access samba password database" );
 143         CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 144         return PAM_AUTHINFO_UNAVAIL;
 145     }
 146
 147     /* obtain user record */
 148     if ( !(sampass = samu_new( NULL )) ) {
 149         CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 150         return nt_status_to_pam(NT_STATUS_NO_MEMORY);
 151     }
 152
 153     if (!pdb_getsampwnam(sampass,user)) {
 154         _log_err( LOG_ALERT, "Failed to find entry for user %s.", user );
 155         CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 156         return PAM_USER_UNKNOWN;
 157     }
 158     if (on( SMB_DEBUG, ctrl )) {
 159         _log_err( LOG_DEBUG, "Located account for %s", user );
 160     }
 161
 162     if (flags & PAM_PRELIM_CHECK) {
 163         /*
 164          * obtain and verify the current password (OLDAUTHTOK) for
 165          * the user.
 166          */
 167
 168         char *Announce;
 169
 170         if (_smb_blankpasswd( ctrl, sampass )) {
 171
 172             TALLOC_FREE(sampass);
 173             CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 174             return PAM_SUCCESS;
 175         }
 176
 177         /* Password change by root, or for an expired token, doesn't
 178            require authentication.  Is this a good choice? */
 179         if (getuid() != 0 && !(flags & PAM_CHANGE_EXPIRED_AUTHTOK)) {
 180
 181             /* tell user what is happening */
 182 #define greeting "Changing password for "
 183             Announce = SMB_MALLOC_ARRAY(char, sizeof(greeting)+strlen(user));
 184             if (Announce == NULL) {
 185                 _log_err(LOG_CRIT, "password: out of memory");
 186                 TALLOC_FREE(sampass);
 187                 CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 188                 return PAM_BUF_ERR;
 189             }
 190             strncpy( Announce, greeting, sizeof(greeting) );
 191             strncpy( Announce+sizeof(greeting)-1, user, strlen(user)+1 );
 192 #undef greeting
 193
 194             set( SMB__OLD_PASSWD, ctrl );
 195             retval = _smb_read_password( pamh, ctrl, Announce, "Current SMB password: ",
 196                                          NULL, _SMB_OLD_AUTHTOK, &pass_old );
 197             SAFE_FREE( Announce );
 198
 199             if (retval != PAM_SUCCESS) {
 200                 _log_err( LOG_NOTICE
 201                           , "password - (old) token not obtained" );
 202                 TALLOC_FREE(sampass);
 203                 CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 204                 return retval;
 205             }
 206
 207             /* verify that this is the password for this user */
 208
 209             retval = _smb_verify_password( pamh, sampass, pass_old, ctrl );
 210
 211         } else {
 212             pass_old = NULL;
 213             retval = PAM_SUCCESS;           /* root doesn't have to */
 214         }
 215
 216         pass_old = NULL;
 217         TALLOC_FREE(sampass);
 218         CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 219         return retval;
 220
 221     } else if (flags & PAM_UPDATE_AUTHTOK) {
 222
 223         /*
 224          * obtain the proposed password
 225          */
 226
 227         /*
 228          * get the old token back. NULL was ok only if root [at this
 229          * point we assume that this has already been enforced on a
 230          * previous call to this function].
 231          */
 232
 233         if (off( SMB_NOT_SET_PASS, ctrl )) {
 234             retval = pam_get_item( pamh, PAM_OLDAUTHTOK,
 235                                    (const void **)&pass_old );
 236         } else {
 237             retval = pam_get_data( pamh, _SMB_OLD_AUTHTOK,
 238                                    (const void **)&pass_old );
 239             if (retval == PAM_NO_MODULE_DATA) {
 240                 pass_old = NULL;
 241                 retval = PAM_SUCCESS;
 242             }
 243         }
 244
 245         if (retval != PAM_SUCCESS) {
 246             _log_err( LOG_NOTICE, "password: user not authenticated" );
 247             TALLOC_FREE(sampass);
 248             CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 249             return retval;
 250         }
 251
 252         /*
 253          * use_authtok is to force the use of a previously entered
 254          * password -- needed for pluggable password strength checking
 255          * or other module stacking
 256          */
 257
 258         if (on( SMB_USE_AUTHTOK, ctrl )) {
 259             set( SMB_USE_FIRST_PASS, ctrl );
 260         }
 261
 262         retval = _smb_read_password( pamh, ctrl
 263                                       , NULL
 264                                       , "Enter new SMB password: "
 265                                       , "Retype new SMB password: "
 266                                       , _SMB_NEW_AUTHTOK
 267                                       , &pass_new );
 268
 269         if (retval != PAM_SUCCESS) {
 270             if (on( SMB_DEBUG, ctrl )) {
 271                 _log_err( LOG_ALERT
 272                           , "password: new password not obtained" );
 273             }
 274             pass_old = NULL;                               /* tidy up */
 275             TALLOC_FREE(sampass);
 276             CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 277             return retval;
 278         }
 279
 280         /*
 281          * At this point we know who the user is and what they
 282          * propose as their new password. Verify that the new
 283          * password is acceptable.
 284          */
 285
 286         if (pass_new[0] == '\0') {     /* "\0" password = NULL */
 287             pass_new = NULL;
 288         }
 289
 290         retval = _pam_smb_approve_pass(pamh, ctrl, pass_old, pass_new);
 291
 292         if (retval != PAM_SUCCESS) {
 293             _log_err(LOG_NOTICE, "new password not acceptable");
 294             pass_new = pass_old = NULL;               /* tidy up */
 295             TALLOC_FREE(sampass);
 296             CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 297             return retval;
 298         }
 299
 300         /*
 301          * By reaching here we have approved the passwords and must now
 302          * rebuild the smb password file.
 303          */
 304
 305         /* update the password database */
 306
 307         retval = smb_update_db(pamh, ctrl, user, pass_new);
 308         if (retval == PAM_SUCCESS) {
 309             uid_t uid;
 310
 311             /* password updated */
 312                 if (!sid_to_uid(pdb_get_user_sid(sampass), &uid)) {
 313                         _log_err( LOG_NOTICE, "Unable to get uid for user %s",
 314                                 pdb_get_username(sampass));
 315                         _log_err( LOG_NOTICE, "password for (%s) changed by (%s/%d)",
 316                                 user, uidtoname(getuid()), getuid());
 317                 } else {
 318                         _log_err( LOG_NOTICE, "password for (%s/%d) changed by (%s/%d)",
 319                                 user, uid, uidtoname(getuid()), getuid());
 320                 }
 321         } else {
 322                 _log_err( LOG_ERR, "password change failed for user %s", user);
 323         }
 324
 325         pass_old = pass_new = NULL;
 326         if (sampass) {
 327                 TALLOC_FREE(sampass);
 328                 sampass = NULL;
 329         }
 330
 331     } else {            /* something has broken with the library */
 332
 333         _log_err( LOG_ALERT, "password received unknown request" );
 334         retval = PAM_ABORT;
 335
 336     }
 337
 338     if (sampass) {
 339         TALLOC_FREE(sampass);
 340         sampass = NULL;
 341     }
 342
 343     TALLOC_FREE(sampass);
 344     CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 345     return retval;
 346 }
 347
 348 /* static module data */
 349 #ifdef PAM_STATIC
 350 struct pam_module _pam_smbpass_passwd_modstruct = {
 351      "pam_smbpass",
 352      NULL,
 353      NULL,
 354      NULL,
 355      NULL,
 356      NULL,
 357      pam_sm_chauthtok
 358 };
 359 #endif
 360