1 /* $OpenBSD: ttymsg.c,v 1.16 2009/10/27 23:59:49 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. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #include <sys/types.h> 34 #include <sys/uio.h> 35 #include <signal.h> 36 #include <fcntl.h> 37 #include <dirent.h> 38 #include <errno.h> 39 #include <paths.h> 40 #include <unistd.h> 41 #include <stdio.h> 42 #include <string.h> 43 #include <stdlib.h> 44 #include <sys/stat.h> 45 46 char *ttymsg(struct iovec *, int, char *, int); 47 48 /* 49 * Display the contents of a uio structure on a terminal. Used by wall(1) 50 * and talkd(8). Forks and finishes in child if write would block, 51 * waiting up to tmout seconds. Returns pointer to error string on unexpected 52 * error; string is not newline-terminated. Various "normal" errors are 53 * ignored (exclusive-use, lack of permission, etc.). 54 */ 55 char * 56 ttymsg(iov, iovcnt, line, tmout) 57 struct iovec *iov; 58 int iovcnt; 59 char *line; 60 int tmout; 61 { 62 static char device[MAXNAMLEN] = _PATH_DEV; 63 static char errbuf[1024]; 64 int cnt, fd, left, wret; 65 struct iovec localiov[6]; 66 int forked = 0; 67 struct stat st; 68 sigset_t mask; 69 70 if (iovcnt > sizeof(localiov) / sizeof(localiov[0])) 71 return ("too many iov's (change code in wall/ttymsg.c)"); 72 73 /* 74 * Ignore lines that start with "ftp" or "uucp". 75 */ 76 if ((strncmp(line, "ftp", 3) == 0) || 77 (strncmp(line, "uucp", 4) == 0)) 78 return (NULL); 79 80 (void) strlcpy(device + sizeof(_PATH_DEV) - 1, line, 81 sizeof(device) - (sizeof(_PATH_DEV) - 1)); 82 if (strchr(device + sizeof(_PATH_DEV) - 1, '/')) { 83 /* A slash is an attempt to break security... */ 84 (void) snprintf(errbuf, sizeof(errbuf), "'/' in \"%s\"", 85 device); 86 return (errbuf); 87 } 88 89 if (getuid()) { 90 if (stat(device, &st) < 0) 91 return (NULL); 92 if ((st.st_mode & S_IWGRP) == 0) 93 return (NULL); 94 } 95 96 /* 97 * open will fail on slip lines or exclusive-use lines 98 * if not running as root; not an error. 99 */ 100 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) { 101 if (errno == EBUSY || errno == EACCES) 102 return (NULL); 103 (void) snprintf(errbuf, sizeof(errbuf), 104 "%s: %s", device, strerror(errno)); 105 return (errbuf); 106 } 107 108 for (cnt = left = 0; cnt < iovcnt; ++cnt) 109 left += iov[cnt].iov_len; 110 111 for (;;) { 112 wret = writev(fd, iov, iovcnt); 113 if (wret >= left) 114 break; 115 if (wret >= 0) { 116 left -= wret; 117 if (iov != localiov) { 118 bcopy(iov, localiov, 119 iovcnt * sizeof(struct iovec)); 120 iov = localiov; 121 } 122 for (cnt = 0; wret >= iov->iov_len; ++cnt) { 123 wret -= iov->iov_len; 124 ++iov; 125 --iovcnt; 126 } 127 if (wret) { 128 char *base = iov->iov_base; 129 130 iov->iov_base = base + wret; 131 iov->iov_len -= wret; 132 } 133 continue; 134 } 135 if (errno == EWOULDBLOCK) { 136 int off = 0; 137 pid_t cpid; 138 139 if (forked) { 140 (void) close(fd); 141 _exit(1); 142 } 143 cpid = fork(); 144 if (cpid < 0) { 145 (void) snprintf(errbuf, sizeof(errbuf), 146 "fork: %s", strerror(errno)); 147 (void) close(fd); 148 return (errbuf); 149 } 150 if (cpid) { /* parent */ 151 (void) close(fd); 152 return (NULL); 153 } 154 forked++; 155 /* wait at most tmout seconds */ 156 (void) signal(SIGALRM, SIG_DFL); 157 (void) signal(SIGTERM, SIG_DFL); /* XXX */ 158 (void) sigemptyset(&mask); 159 (void) sigprocmask(SIG_SETMASK, &mask, NULL); 160 (void) alarm((u_int)tmout); 161 (void) fcntl(fd, O_NONBLOCK, &off); 162 continue; 163 } 164 /* 165 * We get ENODEV on a slip line if we're running as root, 166 * and EIO if the line just went away. 167 */ 168 if (errno == ENODEV || errno == EIO) 169 break; 170 (void) close(fd); 171 if (forked) 172 _exit(1); 173 (void) snprintf(errbuf, sizeof(errbuf), 174 "%s: %s", device, strerror(errno)); 175 return (errbuf); 176 } 177 178 (void) close(fd); 179 if (forked) 180 _exit(0); 181 return (NULL); 182 } 183