1 /* $NetBSD: settimeofday.c,v 1.8 2006/03/09 23:44:43 christos Exp $ */ 2 3 /* 4 * Copyright (c) 2001 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Emmanuel Dreyfus. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. The name of the author may not be used to endorse or promote products 19 * derived from this software without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 26 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 27 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 28 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 29 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include <sys/cdefs.h> 35 #if defined(LIBC_SCCS) && !defined(lint) 36 __RCSID("$NetBSD: settimeofday.c,v 1.8 2006/03/09 23:44:43 christos Exp $"); 37 #endif /* LIBC_SCCS and not lint */ 38 39 #include "namespace.h" 40 41 #include <sys/types.h> 42 #include <sys/ioctl.h> 43 #include <sys/syscall.h> 44 45 #include <sys/clockctl.h> 46 47 #include <errno.h> 48 #include <fcntl.h> 49 #include <paths.h> 50 #include <string.h> 51 #include <time.h> 52 #include <unistd.h> 53 54 #ifdef __weak_alias 55 __weak_alias(settimeofday,_settimeofday) 56 #endif 57 58 int __clockctl_fd = -2; 59 60 int 61 settimeofday(tv, tzp) 62 const struct timeval *tv; 63 const void *tzp; 64 { 65 struct clockctl_settimeofday args; 66 int error; 67 quad_t q; 68 int rv; 69 70 /* 71 * if __clockctl_fd == -1, then this is not our first time, 72 * and we know root is the calling user. We use the system call 73 */ 74 if (__clockctl_fd == -1) { 75 try_syscall: 76 q = __syscall((quad_t)SYS_settimeofday, tv, tzp); 77 if (/* LINTED constant */ sizeof (quad_t) == sizeof (register_t) 78 || /* LINTED constant */ BYTE_ORDER == LITTLE_ENDIAN) 79 rv = (int)q; 80 else 81 rv = (int)((u_quad_t)q >> 32); 82 83 /* 84 * If credentials changed from root to an unprivilegied 85 * user, and we already had __clockctl_fd = -1, then we 86 * tried the system call as a non root user, it failed 87 * with EPERM, and we will try clockctl. 88 */ 89 if (rv != -1 || errno != EPERM) 90 return rv; 91 __clockctl_fd = -2; 92 } 93 94 /* 95 * If __clockctl_fd = -2 then this is our first time here, 96 * or credentials have changed (the calling process dropped root 97 * root privilege). Check if root is the calling user. If it is, 98 * we try the system call, if it is not, we try clockctl. 99 */ 100 if (__clockctl_fd == -2) { 101 /* 102 * Root always uses the syscall 103 */ 104 if (geteuid() == 0) { 105 __clockctl_fd = -1; 106 goto try_syscall; 107 } 108 109 /* 110 * If this fails, it means that we are not root 111 * and we cannot open clockctl. This is a failure. 112 */ 113 __clockctl_fd = open(_PATH_CLOCKCTL, O_WRONLY, 0); 114 if (__clockctl_fd == -1) 115 return -1; 116 (void) fcntl(__clockctl_fd, F_SETFD, FD_CLOEXEC); 117 } 118 119 /* 120 * If __clockctl_fd >=0, clockctl has already been open 121 * and used, so we carry on using it. 122 */ 123 args.tv = tv; 124 args.tzp = tzp; 125 error = ioctl(__clockctl_fd, CLOCKCTL_SETTIMEOFDAY, &args); 126 return error; 127 } 128