text: /* Written by Ricky Zhou <ricky@fedoraproject.org>
   * Fredrik Thulin <fredrik@yubico.com> implemented pam_modutil_drop_priv
   *
   * Copyright (c) 2011-2014 Yubico AB
   * Copyright (c) 2011 Ricky Zhou <ricky@fedoraproject.org>
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are
   * met:
   *
   *     * Redistributions of source code must retain the above copyright
   *       notice, this list of conditions and the following disclaimer.
   *
   *     * Redistributions in binary form must reproduce the above
   *       copyright notice, this list of conditions and the following
   *       disclaimer in the documentation and/or other materials provided
   *       with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #ifndef HAVE_PAM_MODUTIL_DROP_PRIV
  
  #include <unistd.h>
  #include <pwd.h>
  #include <grp.h>
  #include <errno.h>
  #include <string.h>
  #include <stdlib.h>
  
  #include "drop_privs.h"
  #include "util.h"
  
  #ifdef HAVE_SECURITY_PAM_APPL_H
  #include <security/pam_appl.h>
  #endif
  #ifdef HAVE_SECURITY_PAM_MODULES_H
  #include <security/pam_modules.h>
  #endif
  
  
  int pam_modutil_drop_priv(pam_handle_t *pamh, struct _ykpam_privs *privs, const struct passwd *pw) {
      privs->saved_euid = geteuid();
      privs->saved_egid = getegid();
  
      if ((privs->saved_euid == pw->pw_uid) && (privs->saved_egid == pw->pw_gid)) {
          D (("Privilges already dropped, pretend it is all right"));
          return 0;
      }
  
      privs->saved_groups_length = getgroups(0, NULL);
      if (privs->saved_groups_length < 0) {
          D (("getgroups: %s", strerror(errno)));
          return -1;
      }
  
      if (privs->saved_groups_length > SAVED_GROUPS_MAX_LEN) {
          D (("to many groups, limiting."));
          privs->saved_groups_length = SAVED_GROUPS_MAX_LEN;
      }
  
      if (privs->saved_groups_length > 0) {
          if (getgroups(privs->saved_groups_length, privs->saved_groups) < 0) {
              D (("getgroups: %s", strerror(errno)));
              goto free_out;
          }
      }
  
      if (initgroups(pw->pw_name, pw->pw_gid) < 0) {
          D (("initgroups: %s", strerror(errno)));
          goto free_out;
      }
  
      if (setegid(pw->pw_gid) < 0) {
          D (("setegid: %s", strerror(errno)));
          goto free_out;
      }
  
      if (seteuid(pw->pw_uid) < 0) {
          D (("seteuid: %s", strerror(errno)));
          goto free_out;
      }
  
      return 0;
  free_out:
      return -1;
  }
  
  int pam_modutil_regain_priv(pam_handle_t *pamh, struct _ykpam_privs *privs) {
      if ((privs->saved_euid == geteuid()) && (privs->saved_egid == getegid())) {
          D (("Privilges already as requested, pretend it is all right"));
          return 0;
      }
  
      if (seteuid(privs->saved_euid) < 0) {
          D (("seteuid: %s", strerror(errno)));
          return -1;
      }
  
      if (setegid(privs->saved_egid) < 0) {
          D (("setegid: %s", strerror(errno)));
          return -1;
      }
  
      if (setgroups(privs->saved_groups_length, privs->saved_groups) < 0) {
          D (("setgroups: %s", strerror(errno)));
          return -1;
      }
  
      return 0;
  }
  
  #endif // HAVE_PAM_MODUTIL_DROP_PRIV
  