source/pam_smbpass/pam_smb_passwd.c

   1 /* Unix NT password database implementation, version 0.7.5.
   2  *
   3  * This program is free software; you can redistribute it and/or modify it under
   4  * the terms of the GNU General Public License as published by the Free
   5  * Software Foundation; either version 2 of the License, or (at your option)
   6  * any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 675
  15  * Mass Ave, Cambridge, MA 02139, USA.
  16 */
  17
  18 /* indicate the following groups are defined */
  19 #define PAM_SM_PASSWORD
  20
  21 #include "includes.h"
  22
  23 #ifndef LINUX
  24
  25 /* This is only used in the Sun implementation. */
  26 #include <security/pam_appl.h>
  27
  28 #endif  /* LINUX */
  29
  30 #include <security/pam_modules.h>
  31
  32 #include "general.h"
  33
  34 #include "support.h"
  35
  36 int smb_update_db( pam_handle_t *pamh, int ctrl, const char *user,  char *pass_new )
  37 {
  38  char           c;
  39  int            retval, i;
  40  pstring        err_str;
  41  pstring        msg_str;
  42
  43     err_str[0] = '\0';
  44     msg_str[0] = '\0';
  45
  46     retval = local_password_change( user, 0, pass_new, err_str, sizeof(err_str),
  47                                     msg_str, sizeof(msg_str) );
  48
  49     if (!retval) {
  50         if (*err_str) {
  51             err_str[PSTRING_LEN-1] = '\0';
  52             make_remark( pamh, ctrl, PAM_ERROR_MSG, err_str );
  53         }
  54
  55         /* FIXME: what value is appropriate here? */
  56         retval = PAM_AUTHTOK_ERR;
  57     } else {
  58         if (*msg_str) {
  59             msg_str[PSTRING_LEN-1] = '\0';
  60             make_remark( pamh, ctrl, PAM_TEXT_INFO, msg_str );
  61         }
  62         retval = PAM_SUCCESS;
  63     }
  64
  65     return retval;
  66
  67 }
  68
  69
  70 /* data tokens */
  71
  72 #define _SMB_OLD_AUTHTOK  "-SMB-OLD-PASS"
  73 #define _SMB_NEW_AUTHTOK  "-SMB-NEW-PASS"
  74
  75 /*
  76  * FUNCTION: pam_sm_chauthtok()
  77  *
  78  * This function is called twice by the PAM library, once with
  79  * PAM_PRELIM_CHECK set, and then again with PAM_UPDATE_AUTHTOK set.  With
  80  * Linux-PAM, these two passes generally involve first checking the old
  81  * token and then changing the token.  This is what we do here.
  82  *
  83  * Having obtained a new password. The function updates the
  84  * SMB_PASSWD_FILE file (normally, $(LIBDIR)/smbpasswd).
  85  */
  86
  87 int pam_sm_chauthtok(pam_handle_t *pamh, int flags,
  88                      int argc, const char **argv)
  89 {
  90     unsigned int ctrl;
  91     int retval;
  92
  93     extern BOOL in_client;
  94
  95     SAM_ACCOUNT *sampass = NULL;
  96     const char *user;
  97     char *pass_old, *pass_new;
  98
  99     /* Samba initialization. */
 100     setup_logging( "pam_smbpass", False );
 101     charset_initialise();
 102     codepage_initialise(lp_client_code_page());
 103     in_client = True;
 104
 105     ctrl = set_ctrl(flags, argc, argv);
 106
 107     /*
 108      * First get the name of a user.  No need to do anything if we can't
 109      * determine this.
 110      */
 111
 112     retval = pam_get_user( pamh, &user, "Username: " );
 113     if (retval != PAM_SUCCESS) {
 114         if (on( SMB_DEBUG, ctrl )) {
 115             _log_err( LOG_DEBUG, "password: could not identify user" );
 116         }
 117         return retval;
 118     }
 119     if (on( SMB_DEBUG, ctrl )) {
 120         _log_err( LOG_DEBUG, "username [%s] obtained", user );
 121     }
 122
 123     if (!initialize_password_db(True)) {
 124         _log_err( LOG_ALERT, "Cannot access samba password database" );
 125         return PAM_AUTHINFO_UNAVAIL;
 126     }
 127
 128     /* obtain user record */
 129     pdb_init_sam(&sampass);
 130     pdb_getsampwnam(sampass,user);
 131
 132     if (sampass == NULL) {
 133         _log_err( LOG_ALERT, "Failed to find entry for user %s.", user );
 134         return PAM_USER_UNKNOWN;
 135     }
 136
 137     if (flags & PAM_PRELIM_CHECK) {
 138         /*
 139          * obtain and verify the current password (OLDAUTHTOK) for
 140          * the user.
 141          */
 142
 143         char *Announce;
 144
 145         if (_smb_blankpasswd( ctrl, sampass )) {
 146
 147             pdb_free_sam(sampass);
 148             return PAM_SUCCESS;
 149         }
 150
 151         /* Password change by root, or for an expired token, doesn't
 152            require authentication.  Is this a good choice? */
 153         if (getuid() != 0 && !(flags & PAM_CHANGE_EXPIRED_AUTHTOK)) {
 154
 155             /* tell user what is happening */
 156 #define greeting "Changing password for "
 157             Announce = (char *) malloc(sizeof(greeting)+strlen(user));
 158             if (Announce == NULL) {
 159                 _log_err(LOG_CRIT, "password: out of memory");
 160                 pdb_free_sam(sampass);
 161                 return PAM_BUF_ERR;
 162             }
 163             strncpy( Announce, greeting, sizeof(greeting) );
 164             strncpy( Announce+sizeof(greeting)-1, user, strlen(user)+1 );
 165 #undef greeting
 166
 167             set( SMB__OLD_PASSWD, ctrl );
 168             retval = _smb_read_password( pamh, ctrl, Announce, "Current SMB password: ",
 169                                          NULL, _SMB_OLD_AUTHTOK, &pass_old );
 170             SAFE_FREE( Announce );
 171
 172             if (retval != PAM_SUCCESS) {
 173                 _log_err( LOG_NOTICE
 174                           , "password - (old) token not obtained" );
 175                 pdb_free_sam(sampass);
 176                 return retval;
 177             }
 178
 179             /* verify that this is the password for this user */
 180
 181             retval = _smb_verify_password( pamh, sampass, pass_old, ctrl );
 182
 183         } else {
 184             pass_old = NULL;
 185             retval = PAM_SUCCESS;           /* root doesn't have to */
 186         }
 187
 188         pass_old = NULL;
 189         pdb_free_sam(sampass);
 190         return retval;
 191
 192     } else if (flags & PAM_UPDATE_AUTHTOK) {
 193
 194 #if 0
 195         /* We used to return when this flag was set, but that breaks
 196            password synchronization when /other/ tokens are expired.  For
 197            now, we change the password whenever we're asked. SRL */
 198         if (flags & PAM_CHANGE_EXPIRED_AUTHTOK) {
 199             pdb_free_sam(sampass);
 200             return PAM_SUCCESS;
 201         }
 202 #endif
 203         /*
 204          * obtain the proposed password
 205          */
 206
 207         /*
 208          * get the old token back. NULL was ok only if root [at this
 209          * point we assume that this has already been enforced on a
 210          * previous call to this function].
 211          */
 212
 213         if (off( SMB_NOT_SET_PASS, ctrl )) {
 214             retval = pam_get_item( pamh, PAM_OLDAUTHTOK,
 215                                    (const void **)&pass_old );
 216         } else {
 217             retval = pam_get_data( pamh, _SMB_OLD_AUTHTOK,
 218                                    (const void **)&pass_old );
 219             if (retval == PAM_NO_MODULE_DATA) {
 220                 pass_old = NULL;
 221                 retval = PAM_SUCCESS;
 222             }
 223         }
 224
 225         if (retval != PAM_SUCCESS) {
 226             _log_err( LOG_NOTICE, "password: user not authenticated" );
 227             pdb_free_sam(sampass);
 228             return retval;
 229         }
 230
 231         /*
 232          * use_authtok is to force the use of a previously entered
 233          * password -- needed for pluggable password strength checking
 234          * or other module stacking
 235          */
 236
 237         if (on( SMB_USE_AUTHTOK, ctrl )) {
 238             set( SMB_USE_FIRST_PASS, ctrl );
 239         }
 240
 241         retval = _smb_read_password( pamh, ctrl
 242                                       , NULL
 243                                       , "Enter new SMB password: "
 244                                       , "Retype new SMB password: "
 245                                       , _SMB_NEW_AUTHTOK
 246                                       , &pass_new );
 247
 248         if (retval != PAM_SUCCESS) {
 249             if (on( SMB_DEBUG, ctrl )) {
 250                 _log_err( LOG_ALERT
 251                           , "password: new password not obtained" );
 252             }
 253             pass_old = NULL;                               /* tidy up */
 254             pdb_free_sam(sampass);
 255             return retval;
 256         }
 257
 258         /*
 259          * At this point we know who the user is and what they
 260          * propose as their new password. Verify that the new
 261          * password is acceptable.
 262          */
 263
 264         if (pass_new[0] == '\0') {     /* "\0" password = NULL */
 265             pass_new = NULL;
 266         }
 267
 268         retval = _pam_smb_approve_pass(pamh, ctrl, pass_old, pass_new);
 269
 270         if (retval != PAM_SUCCESS) {
 271             _log_err(LOG_NOTICE, "new password not acceptable");
 272             pass_new = pass_old = NULL;               /* tidy up */
 273             pdb_free_sam(sampass);
 274             return retval;
 275         }
 276
 277         /*
 278          * By reaching here we have approved the passwords and must now
 279          * rebuild the smb password file.
 280          */
 281
 282         /* update the password database */
 283
 284         retval = smb_update_db(pamh, ctrl, user, pass_new);
 285         if (retval == PAM_SUCCESS) {
 286             /* password updated */
 287             _log_err( LOG_NOTICE, "password for (%s/%d) changed by (%s/%d)"
 288                       , user, pdb_get_uid(sampass), uidtoname( getuid() )
 289                       , getuid() );
 290         } else {
 291             _log_err( LOG_ERR, "password change failed for user %s"
 292                       , user );
 293         }
 294
 295         pass_old = pass_new = NULL;
 296         if (sampass) {
 297                 pdb_free_sam(sampass);
 298                 sampass = NULL;
 299         }
 300
 301     } else {            /* something has broken with the library */
 302
 303         _log_err( LOG_ALERT, "password received unknown request" );
 304         retval = PAM_ABORT;
 305
 306     }
 307
 308     if (sampass) {
 309         pdb_free_sam(sampass);
 310         sampass = NULL;
 311     }
 312
 313     pdb_free_sam(sampass);
 314     return retval;
 315 }
 316
 317 /* static module data */
 318 #ifdef PAM_STATIC
 319 struct pam_module _pam_smbpass_passwd_modstruct = {
 320      "pam_smbpass",
 321      NULL,
 322      NULL,
 323      NULL,
 324      NULL,
 325      NULL,
 326      pam_sm_chauthtok
 327 };
 328 #endif
 329