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