1 /* $NetBSD: adjtime.c,v 1.7 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: adjtime.c,v 1.7 2006/03/09 23:44:43 christos 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 50 #include <sys/clockctl.h> 51 52 #ifdef __weak_alias 53 __weak_alias(adjtime,_adjtime) 54 #endif 55 56 extern int __clockctl_fd; 57 58 int 59 adjtime(delta, olddelta) 60 const struct timeval *delta; 61 struct timeval *olddelta; 62 { 63 struct clockctl_adjtime args; 64 int error; 65 quad_t q; 66 int rv; 67 68 /* 69 * if __clockctl_fd == -1, then this is not our first time, 70 * and we know root is the calling user. We use the system call 71 */ 72 if (__clockctl_fd == -1) { 73 try_syscall: 74 q = __syscall((quad_t)SYS_adjtime, delta, olddelta); 75 if (/* LINTED constant */ sizeof (quad_t) == sizeof (register_t) 76 || /* LINTED constant */ BYTE_ORDER == LITTLE_ENDIAN) 77 rv = (int)q; 78 else 79 rv = (int)((u_quad_t)q >> 32); 80 81 /* 82 * If credentials changed from root to an unprivilegied 83 * user, and we already had __clockctl_fd = -1, then we 84 * tried the system call as a non root user, it failed 85 * with EPERM, and we will try clockctl. 86 */ 87 if (rv != -1 || errno != EPERM) 88 return rv; 89 __clockctl_fd = -2; 90 } 91 92 /* 93 * If __clockctl_fd = -2 then this is our first time here, 94 * or credentials have changed (the calling process dropped root 95 * root privilege). Check if root is the calling user. If it is, 96 * we try the system call, if it is not, we try clockctl. 97 */ 98 if (__clockctl_fd == -2) { 99 /* 100 * Root always uses the syscall 101 */ 102 if (geteuid() == 0) { 103 __clockctl_fd = -1; 104 goto try_syscall; 105 } 106 107 /* 108 * If this fails, it means that we are not root 109 * and we cannot open clockctl. This is a failure. 110 */ 111 __clockctl_fd = open(_PATH_CLOCKCTL, O_WRONLY, 0); 112 if (__clockctl_fd == -1) 113 return -1; 114 (void) fcntl(__clockctl_fd, F_SETFD, FD_CLOEXEC); 115 } 116 117 /* 118 * If __clockctl_fd >=0, clockctl has already been open 119 * and used, so we carry on using it. 120 */ 121 args.delta = delta; 122 args.olddelta = olddelta; 123 error = ioctl(__clockctl_fd, CLOCKCTL_ADJTIME, &args); 124 return error; 125 126 } 127