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 2 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, write to the Free Software
  18    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19
  20 */
  21
  22 /* indicate the following groups are defined */
  23 #define PAM_SM_PASSWORD
  24
  25 #include "includes.h"
  26
  27 /* This is only used in the Sun implementation.  FIXME: we really
  28    want a define here that distinguishes between the Solaris PAM
  29    and others (including FreeBSD). */
  30
  31 #ifndef LINUX
  32 #include <security/pam_appl.h>
  33 #endif
  34
  35 #include <security/pam_modules.h>
  36
  37 #include "general.h"
  38
  39 #include "support.h"
  40
  41 int smb_update_db( pam_handle_t *pamh, int ctrl, const char *user,  const char *pass_new )
  42 {
  43         int retval;
  44         pstring err_str;
  45         pstring msg_str;
  46
  47         err_str[0] = '\0';
  48         msg_str[0] = '\0';
  49
  50         retval = local_password_change( user, LOCAL_SET_PASSWORD, pass_new,
  51                                         err_str, sizeof(err_str),
  52                                         msg_str, sizeof(msg_str) );
  53
  54         if (!retval) {
  55                 if (*err_str) {
  56                         err_str[PSTRING_LEN-1] = '\0';
  57                         make_remark( pamh, ctrl, PAM_ERROR_MSG, err_str );
  58                 }
  59
  60                 /* FIXME: what value is appropriate here? */
  61                 retval = PAM_AUTHTOK_ERR;
  62         } else {
  63                 if (*msg_str) {
  64                         msg_str[PSTRING_LEN-1] = '\0';
  65                         make_remark( pamh, ctrl, PAM_TEXT_INFO, msg_str );
  66                 }
  67                 retval = PAM_SUCCESS;
  68         }
  69
  70         return retval;
  71 }
  72
  73
  74 /* data tokens */
  75
  76 #define _SMB_OLD_AUTHTOK  "-SMB-OLD-PASS"
  77 #define _SMB_NEW_AUTHTOK  "-SMB-NEW-PASS"
  78
  79 /*
  80  * FUNCTION: pam_sm_chauthtok()
  81  *
  82  * This function is called twice by the PAM library, once with
  83  * PAM_PRELIM_CHECK set, and then again with PAM_UPDATE_AUTHTOK set.  With
  84  * Linux-PAM, these two passes generally involve first checking the old
  85  * token and then changing the token.  This is what we do here.
  86  *
  87  * Having obtained a new password. The function updates the
  88  * SMB_PASSWD_FILE file (normally, $(LIBDIR)/smbpasswd).
  89  */
  90
  91 int pam_sm_chauthtok(pam_handle_t *pamh, int flags,
  92                      int argc, const char **argv)
  93 {
  94     unsigned int ctrl;
  95     int retval;
  96
  97     extern BOOL in_client;
  98
  99     SAM_ACCOUNT *sampass = NULL;
 100     void (*oldsig_handler)(int);
 101     const char *user;
 102     char *pass_old;
 103     char *pass_new;
 104
 105     NTSTATUS nt_status;
 106
 107     /* Samba initialization. */
 108     setup_logging( "pam_smbpass", False );
 109     in_client = True;
 110
 111     ctrl = set_ctrl(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( LOG_DEBUG, "password: could not identify user" );
 122         }
 123         return retval;
 124     }
 125     if (on( SMB_DEBUG, ctrl )) {
 126         _log_err( LOG_DEBUG, "username [%s] obtained", user );
 127     }
 128
 129     /* Getting into places that might use LDAP -- protect the app
 130        from a SIGPIPE it's not expecting */
 131     oldsig_handler = CatchSignal(SIGPIPE, SIGNAL_CAST SIG_IGN);
 132
 133     if (!initialize_password_db(True)) {
 134         _log_err( LOG_ALERT, "Cannot access samba password database" );
 135         CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 136         return PAM_AUTHINFO_UNAVAIL;
 137     }
 138
 139     /* obtain user record */
 140     if (!NT_STATUS_IS_OK(nt_status = pdb_init_sam(&sampass))) {
 141         CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 142         return nt_status_to_pam(nt_status);
 143     }
 144
 145     if (!pdb_getsampwnam(sampass,user)) {
 146         _log_err( LOG_ALERT, "Failed to find entry for user %s.", user );
 147         CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 148         return PAM_USER_UNKNOWN;
 149     }
 150
 151     if (flags & PAM_PRELIM_CHECK) {
 152         /*
 153          * obtain and verify the current password (OLDAUTHTOK) for
 154          * the user.
 155          */
 156
 157         char *Announce;
 158
 159         if (_smb_blankpasswd( ctrl, sampass )) {
 160
 161             pdb_free_sam(&sampass);
 162             CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 163             return PAM_SUCCESS;
 164         }
 165
 166         /* Password change by root, or for an expired token, doesn't
 167            require authentication.  Is this a good choice? */
 168         if (getuid() != 0 && !(flags & PAM_CHANGE_EXPIRED_AUTHTOK)) {
 169
 170             /* tell user what is happening */
 171 #define greeting "Changing password for "
 172             Announce = (char *) malloc(sizeof(greeting)+strlen(user));
 173             if (Announce == NULL) {
 174                 _log_err(LOG_CRIT, "password: out of memory");
 175                 pdb_free_sam(&sampass);
 176                 CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 177                 return PAM_BUF_ERR;
 178             }
 179             strncpy( Announce, greeting, sizeof(greeting) );
 180             strncpy( Announce+sizeof(greeting)-1, user, strlen(user)+1 );
 181 #undef greeting
 182
 183             set( SMB__OLD_PASSWD, ctrl );
 184             retval = _smb_read_password( pamh, ctrl, Announce, "Current SMB password: ",
 185                                          NULL, _SMB_OLD_AUTHTOK, &pass_old );
 186             SAFE_FREE( Announce );
 187
 188             if (retval != PAM_SUCCESS) {
 189                 _log_err( LOG_NOTICE
 190                           , "password - (old) token not obtained" );
 191                 pdb_free_sam(&sampass);
 192                 CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 193                 return retval;
 194             }
 195
 196             /* verify that this is the password for this user */
 197
 198             retval = _smb_verify_password( pamh, sampass, pass_old, ctrl );
 199
 200         } else {
 201             pass_old = NULL;
 202             retval = PAM_SUCCESS;           /* root doesn't have to */
 203         }
 204
 205         pass_old = NULL;
 206         pdb_free_sam(&sampass);
 207         CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 208         return retval;
 209
 210     } else if (flags & PAM_UPDATE_AUTHTOK) {
 211
 212         /*
 213          * obtain the proposed password
 214          */
 215
 216         /*
 217          * get the old token back. NULL was ok only if root [at this
 218          * point we assume that this has already been enforced on a
 219          * previous call to this function].
 220          */
 221
 222         if (off( SMB_NOT_SET_PASS, ctrl )) {
 223             retval = pam_get_item( pamh, PAM_OLDAUTHTOK,
 224                                    (const void **)&pass_old );
 225         } else {
 226             retval = pam_get_data( pamh, _SMB_OLD_AUTHTOK,
 227                                    (const void **)&pass_old );
 228             if (retval == PAM_NO_MODULE_DATA) {
 229                 pass_old = NULL;
 230                 retval = PAM_SUCCESS;
 231             }
 232         }
 233
 234         if (retval != PAM_SUCCESS) {
 235             _log_err( LOG_NOTICE, "password: user not authenticated" );
 236             pdb_free_sam(&sampass);
 237             CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 238             return retval;
 239         }
 240
 241         /*
 242          * use_authtok is to force the use of a previously entered
 243          * password -- needed for pluggable password strength checking
 244          * or other module stacking
 245          */
 246
 247         if (on( SMB_USE_AUTHTOK, ctrl )) {
 248             set( SMB_USE_FIRST_PASS, ctrl );
 249         }
 250
 251         retval = _smb_read_password( pamh, ctrl
 252                                       , NULL
 253                                       , "Enter new SMB password: "
 254                                       , "Retype new SMB password: "
 255                                       , _SMB_NEW_AUTHTOK
 256                                       , &pass_new );
 257
 258         if (retval != PAM_SUCCESS) {
 259             if (on( SMB_DEBUG, ctrl )) {
 260                 _log_err( LOG_ALERT
 261                           , "password: new password not obtained" );
 262             }
 263             pass_old = NULL;                               /* tidy up */
 264             pdb_free_sam(&sampass);
 265             CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 266             return retval;
 267         }
 268
 269         /*
 270          * At this point we know who the user is and what they
 271          * propose as their new password. Verify that the new
 272          * password is acceptable.
 273          */
 274
 275         if (pass_new[0] == '\0') {     /* "\0" password = NULL */
 276             pass_new = NULL;
 277         }
 278
 279         retval = _pam_smb_approve_pass(pamh, ctrl, pass_old, pass_new);
 280
 281         if (retval != PAM_SUCCESS) {
 282             _log_err(LOG_NOTICE, "new password not acceptable");
 283             pass_new = pass_old = NULL;               /* tidy up */
 284             pdb_free_sam(&sampass);
 285             CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 286             return retval;
 287         }
 288
 289         /*
 290          * By reaching here we have approved the passwords and must now
 291          * rebuild the smb password file.
 292          */
 293
 294         /* update the password database */
 295
 296         retval = smb_update_db(pamh, ctrl, user, pass_new);
 297         if (retval == PAM_SUCCESS) {
 298             uid_t uid;
 299
 300             /* password updated */
 301                 if (!NT_STATUS_IS_OK(sid_to_uid(pdb_get_user_sid(sampass), &uid))) {
 302                         _log_err( LOG_NOTICE, "Unable to get uid for user %s",
 303                                 pdb_get_username(sampass));
 304                         _log_err( LOG_NOTICE, "password for (%s) changed by (%s/%d)",
 305                                 user, uidtoname(getuid()), getuid());
 306                 } else {
 307                         _log_err( LOG_NOTICE, "password for (%s/%d) changed by (%s/%d)",
 308                                 user, uid, uidtoname(getuid()), getuid());
 309                 }
 310         } else {
 311                 _log_err( LOG_ERR, "password change failed for user %s", user);
 312         }
 313
 314         pass_old = pass_new = NULL;
 315         if (sampass) {
 316                 pdb_free_sam(&sampass);
 317                 sampass = NULL;
 318         }
 319
 320     } else {            /* something has broken with the library */
 321
 322         _log_err( LOG_ALERT, "password received unknown request" );
 323         retval = PAM_ABORT;
 324
 325     }
 326
 327     if (sampass) {
 328         pdb_free_sam(&sampass);
 329         sampass = NULL;
 330     }
 331
 332     pdb_free_sam(&sampass);
 333     CatchSignal(SIGPIPE, SIGNAL_CAST oldsig_handler);
 334     return retval;
 335 }
 336
 337 /* static module data */
 338 #ifdef PAM_STATIC
 339 struct pam_module _pam_smbpass_passwd_modstruct = {
 340      "pam_smbpass",
 341      NULL,
 342      NULL,
 343      NULL,
 344      NULL,
 345      NULL,
 346      pam_sm_chauthtok
 347 };
 348 #endif
 349