1 /* $NetBSD: adjtime.c,v 1.3 2001/12/09 16:11:45 manu 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 "namespace.h" 35 #include <errno.h> 36 #include <fcntl.h> 37 #include <paths.h> 38 #include <unistd.h> 39 #include <time.h> 40 #include <string.h> 41 #include <sys/types.h> 42 #include <sys/ioctl.h> 43 #include <sys/syscall.h> 44 #include <sys/systm.h> 45 46 #include <sys/clockctl.h> 47 48 #ifdef __weak_alias 49 __weak_alias(adjtime,_adjtime) 50 #endif 51 52 extern int __clockctl_fd; 53 54 int 55 adjtime(delta, olddelta) 56 const struct timeval *delta; 57 struct timeval *olddelta; 58 { 59 struct sys_adjtime_args args; 60 int error; 61 quad_t q; 62 int rv; 63 64 /* 65 * if __clockctl_fd == -1, then this is not our first time, 66 * and we know root is the calling user. We use the system call 67 */ 68 if (__clockctl_fd == -1) { 69 try_syscall: 70 q = __syscall((quad_t)SYS_adjtime, delta, olddelta); 71 if (/* LINTED constant */ sizeof (quad_t) == sizeof (register_t) 72 || /* LINTED constant */ BYTE_ORDER == LITTLE_ENDIAN) 73 rv = (int)q; 74 else 75 rv = (int)((u_quad_t)q >> 32); 76 77 /* 78 * If credentials changed from root to an unprivilegied 79 * user, and we already had __clockctl_fd = -1, then we 80 * tried the system call as a non root user, it failed 81 * with EPERM, and we will try clockctl. 82 */ 83 if (rv != -1 || errno != EPERM) 84 return rv; 85 __clockctl_fd = -2; 86 } 87 88 /* 89 * If __clockctl_fd = -2 then this is our first time here, 90 * or credentials have changed (the calling process dropped root 91 * root privilege). Check if root is the calling user. If it is, 92 * we try the system call, if it is not, we try clockctl. 93 */ 94 if (__clockctl_fd == -2) { 95 /* 96 * Root always uses the syscall 97 */ 98 if (geteuid() == 0) { 99 __clockctl_fd = -1; 100 goto try_syscall; 101 } 102 103 /* 104 * If this fails, it means that we are not root 105 * and we cannot open clockctl. This is a failure. 106 */ 107 __clockctl_fd = open(_PATH_CLOCKCTL, O_WRONLY, 0); 108 if (__clockctl_fd == -1) 109 return -1; 110 } 111 112 /* 113 * If __clockctl_fd >=0, clockctl has already been open 114 * and used, so we carry on using it. 115 */ 116 SCARG(&args, delta) = delta; 117 SCARG(&args, olddelta) = olddelta; 118 error = ioctl(__clockctl_fd, CLOCKCTL_ADJTIME, &args); 119 return error; 120 121 } 122