1 /* $NetBSD: ntp_adjtime.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: ntp_adjtime.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 #include <errno.h> 41 #include <fcntl.h> 42 #include <paths.h> 43 #include <unistd.h> 44 #include <sys/types.h> 45 #include <sys/time.h> 46 #include <sys/timex.h> 47 #include <sys/ioctl.h> 48 #include <sys/syscall.h> 49 #include <sys/systm.h> 50 51 #include <sys/clockctl.h> 52 53 #include <fcntl.h> 54 #include <paths.h> 55 #include <string.h> 56 #include <unistd.h> 57 58 #ifdef __weak_alias 59 __weak_alias(ntp_adjtime,_ntp_adjtime) 60 #endif 61 62 extern int __clockctl_fd; 63 64 int 65 ntp_adjtime(tp) 66 struct timex *tp; 67 { 68 struct clockctl_ntp_adjtime_args args; 69 int error; 70 quad_t q; 71 int rv; 72 73 /* 74 * if __clockctl_fd == -1, then this is not our first time, 75 * and we know root is the calling user. We use the system call 76 */ 77 if (__clockctl_fd == -1) { 78 try_syscall: 79 q = __syscall((quad_t)SYS_ntp_adjtime, tp); 80 if (/* LINTED constant */ sizeof (quad_t) == sizeof (register_t) 81 || /* LINTED constant */ BYTE_ORDER == LITTLE_ENDIAN) 82 rv = (int)q; 83 else 84 rv = (int)((u_quad_t)q >> 32); 85 86 /* 87 * If credentials changed from root to an unprivilegied 88 * user, and we already had __clockctl_fd = -1, then we 89 * tried the system call as a non root user, it failed 90 * with EPERM, and we will try clockctl. 91 */ 92 if (rv != -1 || errno != EPERM) 93 return rv; 94 __clockctl_fd = -2; 95 } 96 97 /* 98 * If __clockctl_fd = -2 then this is our first time here, 99 * or credentials have changed (the calling process dropped root 100 * root privilege). Check if root is the calling user. If it is, 101 * we try the system call, if it is not, we try clockctl. 102 */ 103 if (__clockctl_fd == -2) { 104 /* 105 * Root always uses the syscall 106 */ 107 if (geteuid() == 0) { 108 __clockctl_fd = -1; 109 goto try_syscall; 110 } 111 112 /* 113 * If this fails, it means that we are not root 114 * and we cannot open clockctl. This is a failure. 115 */ 116 __clockctl_fd = open(_PATH_CLOCKCTL, O_WRONLY, 0); 117 if (__clockctl_fd == -1) 118 return -1; 119 (void) fcntl(__clockctl_fd, F_SETFD, FD_CLOEXEC); 120 } 121 122 /* 123 * If __clockctl_fd >=0, clockctl has already been open 124 * and used, so we carry on using it. 125 */ 126 SCARG(&args.uas, tp) = tp; 127 error = ioctl(__clockctl_fd, CLOCKCTL_NTP_ADJTIME, &args); 128 129 /* 130 * There is no way to get retval set through ioctl(), hence we 131 * have to handle it here, using args.retval 132 */ 133 if (error == 0) { 134 rv = (int)args.retval; 135 return rv; 136 } 137 return error; 138 139 } 140