1 /* $NetBSD: clock_settime.c,v 1.6 2005/06/12 05:21:28 lukem 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: clock_settime.c,v 1.6 2005/06/12 05:21:28 lukem 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 #include <sys/systm.h> 45 46 #include <errno.h> 47 #include <fcntl.h> 48 #include <paths.h> 49 #include <string.h> 50 #include <time.h> 51 #include <unistd.h> 52 53 #include <sys/clockctl.h> 54 55 #ifdef __weak_alias 56 __weak_alias(clock_settime,_clock_settime) 57 #endif 58 59 extern int __clockctl_fd; 60 61 int 62 clock_settime(clock_id, tp) 63 clockid_t clock_id; 64 const struct timespec *tp; 65 { 66 struct sys_clock_settime_args args; 67 int error; 68 quad_t q; 69 int rv; 70 71 /* 72 * if __clockctl_fd == -1, then this is not our first time, 73 * and we know root is the calling user. We use the system call 74 */ 75 if (__clockctl_fd == -1) { 76 try_syscall: 77 q = __syscall((quad_t)SYS_clock_settime, clock_id, tp); 78 if (/* LINTED constant */ sizeof (quad_t) == sizeof (register_t) 79 || /* LINTED constant */ BYTE_ORDER == LITTLE_ENDIAN) 80 rv = (int)q; 81 else 82 rv = (int)((u_quad_t)q >> 32); 83 84 /* 85 * If credentials changed from root to an unprivilegied 86 * user, and we already had __clockctl_fd = -1, then we 87 * tried the system call as a non root user, it failed 88 * with EPERM, and we will try clockctl. 89 */ 90 if (rv != -1 || errno != EPERM) 91 return rv; 92 __clockctl_fd = -2; 93 } 94 95 /* 96 * If __clockctl_fd = -2 then this is our first time here, 97 * or credentials have changed (the calling process dropped root 98 * root privilege). Check if root is the calling user. If it is, 99 * we try the system call, if it is not, we try clockctl. 100 */ 101 if (__clockctl_fd == -2) { 102 /* 103 * Root always uses the syscall 104 */ 105 if (geteuid() == 0) { 106 __clockctl_fd = -1; 107 goto try_syscall; 108 } 109 110 /* 111 * If this fails, it means that we are not root 112 * and we cannot open clockctl. This is a failure. 113 */ 114 __clockctl_fd = open(_PATH_CLOCKCTL, O_WRONLY, 0); 115 if (__clockctl_fd == -1) 116 return -1; 117 (void) fcntl(__clockctl_fd, F_SETFD, FD_CLOEXEC); 118 } 119 120 /* 121 * If __clockctl_fd >=0, clockctl has already been open 122 * and used, so we carry on using it. 123 */ 124 SCARG(&args, clock_id) = clock_id; 125 SCARG(&args, tp) = tp; 126 error = ioctl(__clockctl_fd, CLOCKCTL_CLOCK_SETTIME, &args); 127 return error; 128 129 } 130