1 /* $OpenBSD: ttymsg.c,v 1.15 2004/09/14 23:01:31 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 #ifndef lint
34 #if 0
35 static const char sccsid[] = "@(#)ttymsg.c 8.2 (Berkeley) 11/16/93";
36 #endif
37 static const char rcsid[] = "$OpenBSD: ttymsg.c,v 1.15 2004/09/14 23:01:31 deraadt Exp $";
38 #endif /* not lint */
39
40 #include <sys/types.h>
41 #include <sys/uio.h>
42 #include <signal.h>
43 #include <fcntl.h>
44 #include <dirent.h>
45 #include <errno.h>
46 #include <paths.h>
47 #include <unistd.h>
48 #include <stdio.h>
49 #include <string.h>
50 #include <stdlib.h>
51 #include <sys/stat.h>
52
53 char *ttymsg(struct iovec *, int, char *, int);
54
55 /*
56 * Display the contents of a uio structure on a terminal. Used by wall(1)
57 * and talkd(8). Forks and finishes in child if write would block,
58 * waiting up to tmout seconds. Returns pointer to error string on unexpected
59 * error; string is not newline-terminated. Various "normal" errors are
60 * ignored (exclusive-use, lack of permission, etc.).
61 */
62 char *
ttymsg(iov,iovcnt,line,tmout)63 ttymsg(iov, iovcnt, line, tmout)
64 struct iovec *iov;
65 int iovcnt;
66 char *line;
67 int tmout;
68 {
69 static char device[MAXNAMLEN] = _PATH_DEV;
70 static char errbuf[1024];
71 int cnt, fd, left, wret;
72 struct iovec localiov[6];
73 int forked = 0;
74 struct stat st;
75 sigset_t mask;
76
77 if (iovcnt > sizeof(localiov) / sizeof(localiov[0]))
78 return ("too many iov's (change code in wall/ttymsg.c)");
79
80 /*
81 * Ignore lines that start with "ftp" or "uucp".
82 */
83 if ((strncmp(line, "ftp", 3) == 0) ||
84 (strncmp(line, "uucp", 4) == 0))
85 return (NULL);
86
87 (void) strlcpy(device + sizeof(_PATH_DEV) - 1, line,
88 sizeof(device) - (sizeof(_PATH_DEV) - 1));
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 memmove(localiov, iov,
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 char *base = iov->iov_base;
136
137 iov->iov_base = base + wret;
138 iov->iov_len -= wret;
139 }
140 continue;
141 }
142 if (errno == EWOULDBLOCK) {
143 int off = 0;
144 pid_t cpid;
145
146 if (forked) {
147 (void) close(fd);
148 _exit(1);
149 }
150 cpid = fork();
151 if (cpid < 0) {
152 (void) snprintf(errbuf, sizeof(errbuf),
153 "fork: %s", strerror(errno));
154 (void) close(fd);
155 return (errbuf);
156 }
157 if (cpid) { /* parent */
158 (void) close(fd);
159 return (NULL);
160 }
161 forked++;
162 /* wait at most tmout seconds */
163 (void) signal(SIGALRM, SIG_DFL);
164 (void) signal(SIGTERM, SIG_DFL); /* XXX */
165 (void) sigemptyset(&mask);
166 (void) sigprocmask(SIG_SETMASK, &mask, NULL);
167 (void) alarm((u_int)tmout);
168 (void) fcntl(fd, O_NONBLOCK, &off);
169 continue;
170 }
171 /*
172 * We get ENODEV on a slip line if we're running as root,
173 * and EIO if the line just went away.
174 */
175 if (errno == ENODEV || errno == EIO)
176 break;
177 (void) close(fd);
178 if (forked)
179 _exit(1);
180 (void) snprintf(errbuf, sizeof(errbuf),
181 "%s: %s", device, strerror(errno));
182 return (errbuf);
183 }
184
185 (void) close(fd);
186 if (forked)
187 _exit(0);
188 return (NULL);
189 }
190