1 /* $OpenBSD: ttymsg.c,v 1.17 2015/11/05 22:20:11 benno 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/stat.h> 35 #include <sys/uio.h> 36 #include <signal.h> 37 #include <fcntl.h> 38 #include <dirent.h> 39 #include <errno.h> 40 #include <paths.h> 41 #include <unistd.h> 42 #include <stdio.h> 43 #include <string.h> 44 #include <stdlib.h> 45 #include <err.h> 46 47 char *ttymsg(struct iovec *, int, char *, int); 48 49 /* 50 * Display the contents of a uio structure on a terminal. Used by wall(1) 51 * and talkd(8). Forks and finishes in child if write would block, 52 * waiting up to tmout seconds. Returns pointer to error string on unexpected 53 * error; string is not newline-terminated. Various "normal" errors are 54 * ignored (exclusive-use, lack of permission, etc.). 55 */ 56 char * 57 ttymsg(iov, iovcnt, line, tmout) 58 struct iovec *iov; 59 int iovcnt; 60 char *line; 61 int tmout; 62 { 63 static char device[MAXNAMLEN] = _PATH_DEV; 64 static char errbuf[1024]; 65 int cnt, fd, left, wret; 66 struct iovec localiov[6]; 67 int forked = 0; 68 struct stat st; 69 sigset_t mask; 70 71 if (iovcnt > sizeof(localiov) / sizeof(localiov[0])) 72 return ("too many iov's (change code in wall/ttymsg.c)"); 73 74 /* 75 * Ignore lines that start with "ftp" or "uucp". 76 */ 77 if ((strncmp(line, "ftp", 3) == 0) || 78 (strncmp(line, "uucp", 4) == 0)) 79 return (NULL); 80 81 (void) strlcpy(device + sizeof(_PATH_DEV) - 1, line, 82 sizeof(device) - (sizeof(_PATH_DEV) - 1)); 83 if (strchr(device + sizeof(_PATH_DEV) - 1, '/')) { 84 /* A slash is an attempt to break security... */ 85 (void) snprintf(errbuf, sizeof(errbuf), "'/' in \"%s\"", 86 device); 87 return (errbuf); 88 } 89 90 if (getuid()) { 91 if (stat(device, &st) < 0) 92 return (NULL); 93 if ((st.st_mode & S_IWGRP) == 0) 94 return (NULL); 95 } 96 97 /* 98 * open will fail on slip lines or exclusive-use lines 99 * if not running as root; not an error. 100 */ 101 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) { 102 if (errno == EBUSY || errno == EACCES) 103 return (NULL); 104 (void) snprintf(errbuf, sizeof(errbuf), 105 "%s: %s", device, strerror(errno)); 106 return (errbuf); 107 } 108 109 for (cnt = left = 0; cnt < iovcnt; ++cnt) 110 left += iov[cnt].iov_len; 111 112 for (;;) { 113 wret = writev(fd, iov, iovcnt); 114 if (wret >= left) 115 break; 116 if (wret >= 0) { 117 left -= wret; 118 if (iov != localiov) { 119 bcopy(iov, localiov, 120 iovcnt * sizeof(struct iovec)); 121 iov = localiov; 122 } 123 for (cnt = 0; wret >= iov->iov_len; ++cnt) { 124 wret -= iov->iov_len; 125 ++iov; 126 --iovcnt; 127 } 128 if (wret) { 129 char *base = iov->iov_base; 130 131 iov->iov_base = base + wret; 132 iov->iov_len -= wret; 133 } 134 continue; 135 } 136 if (errno == EWOULDBLOCK) { 137 int off = 0; 138 pid_t cpid; 139 140 if (forked) { 141 (void) close(fd); 142 _exit(1); 143 } 144 cpid = fork(); 145 if (cpid < 0) { 146 (void) snprintf(errbuf, sizeof(errbuf), 147 "fork: %s", strerror(errno)); 148 (void) close(fd); 149 return (errbuf); 150 } 151 if (cpid) { /* parent */ 152 (void) close(fd); 153 return (NULL); 154 } 155 156 if (pledge("stdio", NULL) == -1) 157 err(1, "pledge"); 158 159 forked++; 160 /* wait at most tmout seconds */ 161 (void) signal(SIGALRM, SIG_DFL); 162 (void) signal(SIGTERM, SIG_DFL); /* XXX */ 163 (void) sigemptyset(&mask); 164 (void) sigprocmask(SIG_SETMASK, &mask, NULL); 165 (void) alarm((u_int)tmout); 166 (void) fcntl(fd, O_NONBLOCK, &off); 167 continue; 168 } 169 /* 170 * We get ENODEV on a slip line if we're running as root, 171 * and EIO if the line just went away. 172 */ 173 if (errno == ENODEV || errno == EIO) 174 break; 175 (void) close(fd); 176 if (forked) 177 _exit(1); 178 (void) snprintf(errbuf, sizeof(errbuf), 179 "%s: %s", device, strerror(errno)); 180 return (errbuf); 181 } 182 183 (void) close(fd); 184 if (forked) 185 _exit(0); 186 return (NULL); 187 } 188