source/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     struct samu *sampass = NULL;
 102     void (*oldsig_handler)(int);
 103     const char *user;
 104     char *pass_old;
 105     char *pass_new;
 106
 107     /* Samba initialization. */
 108     load_case_tables();
 109     setup_logging( "pam_smbpass", False );
 110     lp_set_in_client(True);
 111
 112     ctrl = set_ctrl(flags, argc, argv);
 113
 114     /*
 115      * First get the name of a user.  No need to do anything if we can't
 116      * determine this.
 117      */
 118
 119     retval = pam_get_user( pamh, &user, "Username: " );
 120     if (retval != PAM_SUCCESS) {
 121         if (on( SMB_DEBUG, ctrl )) {
 122             _log_err( LOG_DEBUG, "password: could not identify user" );
 123         }
 124         return retval;
 125     }
 126     if (on( SMB_DEBUG, ctrl )) {
 127         _log_err( LOG_DEBUG, "username [%s] obtained", user );
 128     }
 129
 130     if (geteuid() != 0) {
 131         _log_err( LOG_DEBUG, "Cannot access samba password database, not running as root.");
 132         return PAM_AUTHINFO_UNAVAIL;
 133     }
 134
 135     /* Getting into places that might use LDAP -- protect the app
 136        from a SIGPIPE it's not expecting */
 137     oldsig_handler = CatchSignal(SIGPIPE, SIGNAL_CAST SIG_IGN);
 138
 139     if (!initialize_password_db(False, NULL)) {
 140         _log_err( LOG_ALERT, "Cannot access samba password database" );
 141         CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 142         return PAM_AUTHINFO_UNAVAIL;
 143     }
 144
 145     /* obtain user record */
 146     if ( !(sampass = samu_new( NULL )) ) {
 147         CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 148         return nt_status_to_pam(NT_STATUS_NO_MEMORY);
 149     }
 150
 151     if (!pdb_getsampwnam(sampass,user)) {
 152         _log_err( LOG_ALERT, "Failed to find entry for user %s.", user );
 153         CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 154         return PAM_USER_UNKNOWN;
 155     }
 156     if (on( SMB_DEBUG, ctrl )) {
 157         _log_err( LOG_DEBUG, "Located account for %s", user );
 158     }
 159
 160     if (flags & PAM_PRELIM_CHECK) {
 161         /*
 162          * obtain and verify the current password (OLDAUTHTOK) for
 163          * the user.
 164          */
 165
 166         char *Announce;
 167
 168         if (_smb_blankpasswd( ctrl, sampass )) {
 169
 170             TALLOC_FREE(sampass);
 171             CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 172             return PAM_SUCCESS;
 173         }
 174
 175         /* Password change by root, or for an expired token, doesn't
 176            require authentication.  Is this a good choice? */
 177         if (getuid() != 0 && !(flags & PAM_CHANGE_EXPIRED_AUTHTOK)) {
 178
 179             /* tell user what is happening */
 180 #define greeting "Changing password for "
 181             Announce = SMB_MALLOC_ARRAY(char, sizeof(greeting)+strlen(user));
 182             if (Announce == NULL) {
 183                 _log_err(LOG_CRIT, "password: out of memory");
 184                 TALLOC_FREE(sampass);
 185                 CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 186                 return PAM_BUF_ERR;
 187             }
 188             strncpy( Announce, greeting, sizeof(greeting) );
 189             strncpy( Announce+sizeof(greeting)-1, user, strlen(user)+1 );
 190 #undef greeting
 191
 192             set( SMB__OLD_PASSWD, ctrl );
 193             retval = _smb_read_password( pamh, ctrl, Announce, "Current SMB password: ",
 194                                          NULL, _SMB_OLD_AUTHTOK, &pass_old );
 195             SAFE_FREE( Announce );
 196
 197             if (retval != PAM_SUCCESS) {
 198                 _log_err( LOG_NOTICE
 199                           , "password - (old) token not obtained" );
 200                 TALLOC_FREE(sampass);
 201                 CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 202                 return retval;
 203             }
 204
 205             /* verify that this is the password for this user */
 206
 207             retval = _smb_verify_password( pamh, sampass, pass_old, ctrl );
 208
 209         } else {
 210             pass_old = NULL;
 211             retval = PAM_SUCCESS;           /* root doesn't have to */
 212         }
 213
 214         pass_old = NULL;
 215         TALLOC_FREE(sampass);
 216         CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 217         return retval;
 218
 219     } else if (flags & PAM_UPDATE_AUTHTOK) {
 220
 221         /*
 222          * obtain the proposed password
 223          */
 224
 225         /*
 226          * get the old token back. NULL was ok only if root [at this
 227          * point we assume that this has already been enforced on a
 228          * previous call to this function].
 229          */
 230
 231         if (off( SMB_NOT_SET_PASS, ctrl )) {
 232             retval = pam_get_item( pamh, PAM_OLDAUTHTOK,
 233                                    (const void **)&pass_old );
 234         } else {
 235             retval = pam_get_data( pamh, _SMB_OLD_AUTHTOK,
 236                                    (const void **)&pass_old );
 237             if (retval == PAM_NO_MODULE_DATA) {
 238                 pass_old = NULL;
 239                 retval = PAM_SUCCESS;
 240             }
 241         }
 242
 243         if (retval != PAM_SUCCESS) {
 244             _log_err( LOG_NOTICE, "password: user not authenticated" );
 245             TALLOC_FREE(sampass);
 246             CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 247             return retval;
 248         }
 249
 250         /*
 251          * use_authtok is to force the use of a previously entered
 252          * password -- needed for pluggable password strength checking
 253          * or other module stacking
 254          */
 255
 256         if (on( SMB_USE_AUTHTOK, ctrl )) {
 257             set( SMB_USE_FIRST_PASS, ctrl );
 258         }
 259
 260         retval = _smb_read_password( pamh, ctrl
 261                                       , NULL
 262                                       , "Enter new SMB password: "
 263                                       , "Retype new SMB password: "
 264                                       , _SMB_NEW_AUTHTOK
 265                                       , &pass_new );
 266
 267         if (retval != PAM_SUCCESS) {
 268             if (on( SMB_DEBUG, ctrl )) {
 269                 _log_err( LOG_ALERT
 270                           , "password: new password not obtained" );
 271             }
 272             pass_old = NULL;                               /* tidy up */
 273             TALLOC_FREE(sampass);
 274             CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 275             return retval;
 276         }
 277
 278         /*
 279          * At this point we know who the user is and what they
 280          * propose as their new password. Verify that the new
 281          * password is acceptable.
 282          */
 283
 284         if (pass_new[0] == '\0') {     /* "\0" password = NULL */
 285             pass_new = NULL;
 286         }
 287
 288         retval = _pam_smb_approve_pass(pamh, ctrl, pass_old, pass_new);
 289
 290         if (retval != PAM_SUCCESS) {
 291             _log_err(LOG_NOTICE, "new password not acceptable");
 292             pass_new = pass_old = NULL;               /* tidy up */
 293             TALLOC_FREE(sampass);
 294             CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 295             return retval;
 296         }
 297
 298         /*
 299          * By reaching here we have approved the passwords and must now
 300          * rebuild the smb password file.
 301          */
 302
 303         /* update the password database */
 304
 305         retval = smb_update_db(pamh, ctrl, user, pass_new);
 306         if (retval == PAM_SUCCESS) {
 307             uid_t uid;
 308
 309             /* password updated */
 310                 if (!sid_to_uid(pdb_get_user_sid(sampass), &uid)) {
 311                         _log_err( LOG_NOTICE, "Unable to get uid for user %s",
 312                                 pdb_get_username(sampass));
 313                         _log_err( LOG_NOTICE, "password for (%s) changed by (%s/%d)",
 314                                 user, uidtoname(getuid()), getuid());
 315                 } else {
 316                         _log_err( LOG_NOTICE, "password for (%s/%d) changed by (%s/%d)",
 317                                 user, uid, uidtoname(getuid()), getuid());
 318                 }
 319         } else {
 320                 _log_err( LOG_ERR, "password change failed for user %s", user);
 321         }
 322
 323         pass_old = pass_new = NULL;
 324         if (sampass) {
 325                 TALLOC_FREE(sampass);
 326                 sampass = NULL;
 327         }
 328
 329     } else {            /* something has broken with the library */
 330
 331         _log_err( LOG_ALERT, "password received unknown request" );
 332         retval = PAM_ABORT;
 333
 334     }
 335
 336     if (sampass) {
 337         TALLOC_FREE(sampass);
 338         sampass = NULL;
 339     }
 340
 341     TALLOC_FREE(sampass);
 342     CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 343     return retval;
 344 }
 345
 346 /* static module data */
 347 #ifdef PAM_STATIC
 348 struct pam_module _pam_smbpass_passwd_modstruct = {
 349      "pam_smbpass",
 350      NULL,
 351      NULL,
 352      NULL,
 353      NULL,
 354      NULL,
 355      pam_sm_chauthtok
 356 };
 357 #endif
 358