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