1/* 2 Unix SMB/CIFS implementation. 3 4 gain/lose root privileges 5 6 Copyright (C) Andrew Tridgell 2004 7 8 This program is free software; you can redistribute it and/or modify 9 it under the terms of the GNU General Public License as published by 10 the Free Software Foundation; either version 3 of the License, or 11 (at your option) any later version. 12 13 This program is distributed in the hope that it will be useful, 14 but WITHOUT ANY WARRANTY; without even the implied warranty of 15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 GNU General Public License for more details. 17 18 You should have received a copy of the GNU General Public License 19 along with this program. If not, see <http://www.gnu.org/licenses/>. 20*/ 21 22#include "includes.h" 23#include "system/filesys.h" 24#include "../lib/util/unix_privs.h" 25 26/** 27 * @file 28 * @brief Gaining/losing root privileges 29 */ 30 31/* 32 there are times when smbd needs to temporarily gain root privileges 33 to do some operation. To do this you call root_privileges(), which 34 returns a talloc handle. To restore your previous privileges 35 talloc_free() this pointer. 36 37 Note that this call is considered successful even if it does not 38 manage to gain root privileges, but it will call smb_abort() if it 39 fails to restore the privileges afterwards. The logic is that 40 failing to gain root access can be caught by whatever operation 41 needs to be run as root failing, but failing to lose the root 42 privileges is dangerous. 43 44 This also means that this code is safe to be called from completely 45 unprivileged processes. 46*/ 47 48struct saved_state { 49 uid_t uid; 50}; 51 52static int privileges_destructor(struct saved_state *s) 53{ 54 if (geteuid() != s->uid && 55 seteuid(s->uid) != 0) { 56 smb_panic("Failed to restore privileges"); 57 } 58 return 0; 59} 60 61/** 62 * Obtain root privileges for the current process. 63 * 64 * The privileges can be dropped by talloc_free()-ing the 65 * token returned by this function 66 */ 67void *root_privileges(void) 68{ 69 struct saved_state *s; 70 s = talloc(NULL, struct saved_state); 71 if (!s) return NULL; 72 s->uid = geteuid(); 73 if (s->uid != 0) { 74 seteuid(0); 75 } 76 talloc_set_destructor(s, privileges_destructor); 77 return s; 78} 79