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