/* Unix SMB/CIFS implementation. gain/lose root privileges Copyright (C) Andrew Tridgell 2004 This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ #include "includes.h" #include "system/filesys.h" #include "../lib/util/unix_privs.h" /** * @file * @brief Gaining/losing root privileges */ /* there are times when smbd needs to temporarily gain root privileges to do some operation. To do this you call root_privileges(), which returns a talloc handle. To restore your previous privileges talloc_free() this pointer. Note that this call is considered successful even if it does not manage to gain root privileges, but it will call smb_abort() if it fails to restore the privileges afterwards. The logic is that failing to gain root access can be caught by whatever operation needs to be run as root failing, but failing to lose the root privileges is dangerous. This also means that this code is safe to be called from completely unprivileged processes. */ struct saved_state { uid_t uid; }; static int privileges_destructor(struct saved_state *s) { if (geteuid() != s->uid && seteuid(s->uid) != 0) { smb_panic("Failed to restore privileges"); } return 0; } /** * Obtain root privileges for the current process. * * The privileges can be dropped by talloc_free()-ing the * token returned by this function */ void *root_privileges(void) { struct saved_state *s; s = talloc(NULL, struct saved_state); if (!s) return NULL; s->uid = geteuid(); if (s->uid != 0) { seteuid(0); } talloc_set_destructor(s, privileges_destructor); return s; }