1 /* $OpenBSD: ttymsg.c,v 1.6 1998/11/18 16:47:01 deraadt Exp $ */ 2 /* $NetBSD: ttymsg.c,v 1.3 1994/11/17 07:17:55 jtc Exp $ */ 3 4 /* 5 * Copyright (c) 1989, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #ifndef lint 38 #if 0 39 static char sccsid[] = "@(#)ttymsg.c 8.2 (Berkeley) 11/16/93"; 40 #endif 41 static char rcsid[] = "$OpenBSD: ttymsg.c,v 1.6 1998/11/18 16:47:01 deraadt Exp $"; 42 #endif /* not lint */ 43 44 #include <sys/types.h> 45 #include <sys/uio.h> 46 #include <signal.h> 47 #include <fcntl.h> 48 #include <dirent.h> 49 #include <errno.h> 50 #include <paths.h> 51 #include <unistd.h> 52 #include <stdio.h> 53 #include <string.h> 54 #include <stdlib.h> 55 #include <sys/stat.h> 56 57 /* 58 * Display the contents of a uio structure on a terminal. Used by wall(1), 59 * syslogd(8), and talkd(8). Forks and finishes in child if write would block, 60 * waiting up to tmout seconds. Returns pointer to error string on unexpected 61 * error; string is not newline-terminated. Various "normal" errors are 62 * ignored (exclusive-use, lack of permission, etc.). 63 */ 64 char * 65 ttymsg(iov, iovcnt, line, tmout) 66 struct iovec *iov; 67 int iovcnt; 68 char *line; 69 int tmout; 70 { 71 static char device[MAXNAMLEN] = _PATH_DEV; 72 static char errbuf[1024]; 73 register int cnt, fd, left, wret; 74 struct iovec localiov[6]; 75 int forked = 0; 76 struct stat st; 77 78 if (iovcnt > sizeof(localiov) / sizeof(localiov[0])) 79 return ("too many iov's (change code in wall/ttymsg.c)"); 80 81 /* 82 * Ignore lines that start with "ftp" or "uucp". 83 */ 84 if ((strncmp(line, "ftp", 3) == 0) 85 || (strncmp(line, "uucp", 4) == 0)) 86 return (NULL); 87 88 (void) strcpy(device + sizeof(_PATH_DEV) - 1, line); 89 if (strchr(device + sizeof(_PATH_DEV) - 1, '/')) { 90 /* A slash is an attempt to break security... */ 91 (void) snprintf(errbuf, sizeof(errbuf), "'/' in \"%s\"", 92 device); 93 return (errbuf); 94 } 95 96 if (getuid()) { 97 if (stat(device, &st) < 0) 98 return (NULL); 99 if ((st.st_mode & S_IWGRP) == 0) 100 return (NULL); 101 } 102 103 /* 104 * open will fail on slip lines or exclusive-use lines 105 * if not running as root; not an error. 106 */ 107 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) { 108 if (errno == EBUSY || errno == EACCES) 109 return (NULL); 110 (void) snprintf(errbuf, sizeof(errbuf), 111 "%s: %s", device, strerror(errno)); 112 return (errbuf); 113 } 114 115 for (cnt = left = 0; cnt < iovcnt; ++cnt) 116 left += iov[cnt].iov_len; 117 118 for (;;) { 119 wret = writev(fd, iov, iovcnt); 120 if (wret >= left) 121 break; 122 if (wret >= 0) { 123 left -= wret; 124 if (iov != localiov) { 125 bcopy(iov, localiov, 126 iovcnt * sizeof(struct iovec)); 127 iov = localiov; 128 } 129 for (cnt = 0; wret >= iov->iov_len; ++cnt) { 130 wret -= iov->iov_len; 131 ++iov; 132 --iovcnt; 133 } 134 if (wret) { 135 iov->iov_base += wret; 136 iov->iov_len -= wret; 137 } 138 continue; 139 } 140 if (errno == EWOULDBLOCK) { 141 int cpid, off = 0; 142 143 if (forked) { 144 (void) close(fd); 145 _exit(1); 146 } 147 cpid = fork(); 148 if (cpid < 0) { 149 (void) snprintf(errbuf, sizeof(errbuf), 150 "fork: %s", strerror(errno)); 151 (void) close(fd); 152 return (errbuf); 153 } 154 if (cpid) { /* parent */ 155 (void) close(fd); 156 return (NULL); 157 } 158 forked++; 159 /* wait at most tmout seconds */ 160 (void) signal(SIGALRM, SIG_DFL); 161 (void) signal(SIGTERM, SIG_DFL); /* XXX */ 162 (void) sigsetmask(0); 163 (void) alarm((u_int)tmout); 164 (void) fcntl(fd, O_NONBLOCK, &off); 165 continue; 166 } 167 /* 168 * We get ENODEV on a slip line if we're running as root, 169 * and EIO if the line just went away. 170 */ 171 if (errno == ENODEV || errno == EIO) 172 break; 173 (void) close(fd); 174 if (forked) 175 _exit(1); 176 (void) snprintf(errbuf, sizeof(errbuf), 177 "%s: %s", device, strerror(errno)); 178 return (errbuf); 179 } 180 181 (void) close(fd); 182 if (forked) 183 _exit(0); 184 return (NULL); 185 } 186