Annotation of src/usr.bin/wall/ttymsg.c, Revision 1.18
1.18 ! deraadt 1: /* $OpenBSD: ttymsg.c,v 1.17 2015/11/05 22:20:11 benno Exp $ */
1.1 deraadt 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.
1.12 millert 16: * 3. Neither the name of the University nor the names of its contributors
1.1 deraadt 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>
1.17 benno 34: #include <sys/stat.h>
1.1 deraadt 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>
1.17 benno 45: #include <err.h>
1.13 deraadt 46:
47: char *ttymsg(struct iovec *, int, char *, int);
1.1 deraadt 48:
49: /*
1.14 avsm 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,
1.1 deraadt 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];
1.9 mpech 65: int cnt, fd, left, wret;
1.1 deraadt 66: struct iovec localiov[6];
67: int forked = 0;
1.5 deraadt 68: struct stat st;
1.7 millert 69: sigset_t mask;
1.1 deraadt 70:
71: if (iovcnt > sizeof(localiov) / sizeof(localiov[0]))
72: return ("too many iov's (change code in wall/ttymsg.c)");
1.3 downsj 73:
74: /*
75: * Ignore lines that start with "ftp" or "uucp".
76: */
1.11 deraadt 77: if ((strncmp(line, "ftp", 3) == 0) ||
78: (strncmp(line, "uucp", 4) == 0))
1.3 downsj 79: return (NULL);
1.1 deraadt 80:
1.11 deraadt 81: (void) strlcpy(device + sizeof(_PATH_DEV) - 1, line,
82: sizeof(device) - (sizeof(_PATH_DEV) - 1));
1.1 deraadt 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: }
1.5 deraadt 89:
1.1 deraadt 90: /*
91: * open will fail on slip lines or exclusive-use lines
92: * if not running as root; not an error.
93: */
94: if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) {
1.6 deraadt 95: if (errno == EBUSY || errno == EACCES)
1.1 deraadt 96: return (NULL);
97: (void) snprintf(errbuf, sizeof(errbuf),
98: "%s: %s", device, strerror(errno));
99: return (errbuf);
1.18 ! deraadt 100: }
! 101:
! 102: if (getuid()) {
! 103: if (fstat(fd, &st) < 0 ||
! 104: (st.st_mode & S_IWGRP) == 0) {
! 105: close(fd);
! 106: return (NULL);
! 107: }
1.1 deraadt 108: }
109:
110: for (cnt = left = 0; cnt < iovcnt; ++cnt)
111: left += iov[cnt].iov_len;
112:
113: for (;;) {
114: wret = writev(fd, iov, iovcnt);
115: if (wret >= left)
116: break;
117: if (wret >= 0) {
118: left -= wret;
119: if (iov != localiov) {
120: bcopy(iov, localiov,
121: iovcnt * sizeof(struct iovec));
122: iov = localiov;
123: }
124: for (cnt = 0; wret >= iov->iov_len; ++cnt) {
125: wret -= iov->iov_len;
126: ++iov;
127: --iovcnt;
128: }
129: if (wret) {
1.15 deraadt 130: char *base = iov->iov_base;
131:
132: iov->iov_base = base + wret;
1.1 deraadt 133: iov->iov_len -= wret;
134: }
135: continue;
136: }
137: if (errno == EWOULDBLOCK) {
1.10 deraadt 138: int off = 0;
139: pid_t cpid;
1.1 deraadt 140:
141: if (forked) {
142: (void) close(fd);
143: _exit(1);
144: }
145: cpid = fork();
146: if (cpid < 0) {
147: (void) snprintf(errbuf, sizeof(errbuf),
148: "fork: %s", strerror(errno));
149: (void) close(fd);
150: return (errbuf);
151: }
152: if (cpid) { /* parent */
153: (void) close(fd);
154: return (NULL);
155: }
1.17 benno 156:
157: if (pledge("stdio", NULL) == -1)
158: err(1, "pledge");
159:
1.1 deraadt 160: forked++;
161: /* wait at most tmout seconds */
162: (void) signal(SIGALRM, SIG_DFL);
163: (void) signal(SIGTERM, SIG_DFL); /* XXX */
1.7 millert 164: (void) sigemptyset(&mask);
165: (void) sigprocmask(SIG_SETMASK, &mask, NULL);
1.1 deraadt 166: (void) alarm((u_int)tmout);
167: (void) fcntl(fd, O_NONBLOCK, &off);
168: continue;
169: }
170: /*
171: * We get ENODEV on a slip line if we're running as root,
172: * and EIO if the line just went away.
173: */
174: if (errno == ENODEV || errno == EIO)
175: break;
176: (void) close(fd);
177: if (forked)
178: _exit(1);
179: (void) snprintf(errbuf, sizeof(errbuf),
180: "%s: %s", device, strerror(errno));
181: return (errbuf);
182: }
183:
184: (void) close(fd);
185: if (forked)
186: _exit(0);
187: return (NULL);
188: }