1/*	$NetBSD: mail.local.c,v 1.33 2023/09/06 22:08:38 christos Exp $	*/
2
3/*-
4 * Copyright (c) 1990, 1993, 1994
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33#ifndef lint
34__COPYRIGHT("@(#) Copyright (c) 1990, 1993, 1994\
35 The Regents of the University of California.  All rights reserved.");
36#if 0
37static char sccsid[] = "@(#)mail.local.c	8.22 (Berkeley) 6/21/95";
38#else
39__RCSID("$NetBSD: mail.local.c,v 1.33 2023/09/06 22:08:38 christos Exp $");
40#endif
41#endif /* not lint */
42
43#include <sys/param.h>
44#include <sys/stat.h>
45#include <sys/socket.h>
46
47#include <netinet/in.h>
48
49#include <errno.h>
50#include <fcntl.h>
51#include <pwd.h>
52#include <netdb.h>
53#include <stdarg.h>
54#include <stdbool.h>
55#include <stdio.h>
56#include <stdlib.h>
57#include <string.h>
58#include <syslog.h>
59#include <time.h>
60#include <unistd.h>
61#include <sysexits.h>
62
63
64#include "pathnames.h"
65
66static int	deliver(int, char *, int);
67__dead static void	logerr(int, const char *, ...) __printflike(2, 3);
68static void	logwarn(const char *, ...) __printflike(1, 2);
69static void	notifybiff(char *);
70static int	store(const char *);
71__dead static void	usage(void);
72
73int
74main(int argc, char *argv[])
75{
76	struct passwd *pw;
77	int ch, fd, eval, lockfile = 0;
78	uid_t uid;
79	const char *from;
80
81	/* use a reasonable umask */
82	(void) umask(0077);
83
84	openlog("mail.local", LOG_PERROR, LOG_MAIL);
85
86	from = NULL;
87	while ((ch = getopt(argc, argv, "ldf:r:")) != -1)
88		switch (ch) {
89		case 'd':		/* backward compatible */
90			break;
91		case 'f':
92		case 'r':		/* backward compatible */
93			if (from)
94				logerr(EX_USAGE, "multiple -f options");
95			from = optarg;
96			break;
97		case 'l':
98			lockfile++;
99			break;
100		case '?':
101		default:
102			usage();
103		}
104	argc -= optind;
105	argv += optind;
106
107	if (!*argv)
108		usage();
109
110	/*
111	 * If from not specified, use the name from getlogin() if the
112	 * uid matches, otherwise, use the name from the password file
113	 * corresponding to the uid.
114	 */
115	uid = getuid();
116	if (!from && (!(from = getlogin()) ||
117	    !(pw = getpwnam(from)) || pw->pw_uid != uid))
118		from = (pw = getpwuid(uid)) ? pw->pw_name : "???";
119
120	fd = store(from);
121	for (eval = EX_OK; *argv; ++argv) {
122		int rval;
123
124		rval = deliver(fd, *argv, lockfile);
125		if (eval == EX_OK && rval != EX_OK)
126			eval = rval;
127	}
128	return eval;
129}
130
131static int
132store(const char *from)
133{
134	FILE *fp = NULL;	/* XXX gcc */
135	time_t tval;
136	int fd, eline;
137	char *tn, line[2048];
138
139	tn = strdup(_PATH_LOCTMP);
140	if (!tn)
141		logerr(EX_OSERR, "not enough memory");
142	if ((fd = mkstemp(tn)) == -1 || !(fp = fdopen(fd, "w+")))
143		logerr(EX_OSERR, "unable to open temporary file");
144	(void)unlink(tn);
145	free(tn);
146
147	(void)time(&tval);
148	(void)fprintf(fp, "From %s %s", from, ctime(&tval));
149
150	line[0] = '\0';
151	for (eline = 1; fgets(line, sizeof(line), stdin);) {
152		if (line[0] == '\n')
153			eline = 1;
154		else {
155			if (eline && line[0] == 'F' && !memcmp(line, "From ", 5))
156				(void)putc('>', fp);
157			eline = 0;
158		}
159		(void)fprintf(fp, "%s", line);
160		if (ferror(fp))
161			break;
162	}
163
164	/* If message not newline terminated, need an extra. */
165	if (!index(line, '\n'))
166		(void)putc('\n', fp);
167	/* Output a newline; note, empty messages are allowed. */
168	(void)putc('\n', fp);
169
170	(void)fflush(fp);
171	if (ferror(fp))
172		logerr(EX_OSERR, "temporary file write error");
173	if ((fd = dup(fd)) == -1)
174		logerr(EX_OSERR, "dup failed");
175	(void)fclose(fp);
176	return fd;
177}
178
179static bool
180badfile(const char *path, const struct stat *sb)
181{
182	if (!S_ISREG(sb->st_mode)) {
183		logwarn("%s: not a regular file", path);
184		return true;
185	}
186
187	if (sb->st_nlink != 1) {
188		logwarn("%s: linked file", path);
189		return true;
190	}
191	return false;
192}
193
194static int
195deliver(int fd, char *name, int lockfile)
196{
197	struct stat sb, nsb;
198	struct passwd pwres, *pw;
199	char pwbuf[1024];
200	int created = 0, mbfd = -1, nr, nw, off, rval = EX_OSERR, lfd = -1;
201	char biffmsg[100], buf[8*1024], path[MAXPATHLEN], lpath[MAXPATHLEN];
202	off_t curoff;
203
204	/*
205	 * Disallow delivery to unknown names -- special mailboxes can be
206	 * handled in the sendmail aliases file.
207	 */
208	if ((getpwnam_r(name, &pwres, pwbuf, sizeof(pwbuf), &pw)) != 0) {
209		logwarn("unable to find user %s: %s", name, strerror(errno));
210		return EX_TEMPFAIL;
211	}
212	if (pw == NULL) {
213		logwarn("unknown name: %s", name);
214		return EX_NOUSER;
215	}
216
217	(void)snprintf(path, sizeof path, "%s/%s", _PATH_MAILDIR, name);
218
219	if (lockfile) {
220		(void)snprintf(lpath, sizeof lpath, "%s/%s.lock",
221		    _PATH_MAILDIR, name);
222
223		if((lfd = open(lpath, O_CREAT|O_WRONLY|O_EXCL,
224		    S_IRUSR|S_IWUSR)) < 0) {
225			logwarn("%s: can't create: %s", lpath, strerror(errno));
226			return EX_OSERR;
227		}
228	}
229
230	if (lstat(path, &sb) == -1) {
231		if (errno != ENOENT) {
232			logwarn("%s: can't stat: %s", path, strerror(errno));
233			goto bad;
234		}
235		memset(&sb, 0, sizeof(sb));
236		sb.st_dev = NODEV;
237	} else if (badfile(path, &sb)) {
238		goto bad;
239	}
240
241	if ((mbfd = open(path, O_APPEND|O_WRONLY|O_EXLOCK|O_NOFOLLOW,
242	    S_IRUSR|S_IWUSR)) == -1) {
243		/* create file */
244		if (errno != ENOENT ||
245		   (mbfd = open(path, O_APPEND|O_CREAT|O_WRONLY|O_EXLOCK|O_EXCL,
246		     S_IRUSR|S_IWUSR)) == -1) {
247			logwarn("%s: can't create: %s", path, strerror(errno));
248			goto bad;
249		}
250		created = 1;
251	} else {
252		/* opened existing file, check for TOCTTOU */
253		if (fstat(mbfd, &nsb) == -1) {
254			logwarn("%s: can't stat: %s", path, strerror(errno));
255			goto bad;
256		}
257
258		if (badfile(path, &nsb)) {
259			goto bad;
260		}
261
262		/* file is not what we expected */
263		if (nsb.st_ino != sb.st_ino || nsb.st_dev != sb.st_dev) {
264			logwarn("%s: file has changed", path);
265			goto bad;
266		}
267	}
268
269	if ((curoff = lseek(mbfd, 0, SEEK_END)) == (off_t)-1) {
270		logwarn("%s: can't seek: %s", path, strerror(errno));
271		goto bad;
272	}
273
274	(void)snprintf(biffmsg, sizeof biffmsg, "%s@%lld\n", name,
275	    (long long)curoff);
276	if (lseek(fd, 0, SEEK_SET) == (off_t)-1) {
277		logwarn("can't seek: %s", strerror(errno));
278		goto bad;
279	}
280
281	while ((nr = read(fd, buf, sizeof(buf))) > 0)
282		for (off = 0; off < nr;  off += nw)
283			if ((nw = write(mbfd, buf + off, nr - off)) < 0) {
284				logwarn("%s: can't write: %s", path,
285				    strerror(errno));
286				goto trunc;
287			}
288
289	if (nr < 0) {
290		logwarn("can't read: %s", strerror(errno));
291trunc:		(void)ftruncate(mbfd, curoff);
292		goto bad;
293	}
294
295	rval = EX_OK;
296	/*
297	 * Set the owner and group.  Historically, binmail repeated this at
298	 * each mail delivery.  We no longer do this, assuming that if the
299	 * ownership or permissions were changed there was a reason for doing
300	 * so.
301	 */
302bad:
303	if (lockfile) {
304		if (lfd >= 0) {
305			unlink(lpath);
306			close(lfd);
307		}
308	}
309
310	if (mbfd >= 0) {
311		if (created)
312			(void)fchown(mbfd, pw->pw_uid, pw->pw_gid);
313
314		(void)fsync(mbfd);		/* Don't wait for update. */
315		(void)close(mbfd);		/* Implicit unlock. */
316	}
317
318	if (rval == EX_OK)
319		notifybiff(biffmsg);
320
321	return rval;
322}
323
324void
325notifybiff(char *msg)
326{
327	static struct sockaddr_in addr;
328	static int f = -1;
329	struct hostent *hp;
330	struct servent *sp;
331	int len;
332
333	if (!addr.sin_family) {
334		/* Be silent if biff service not available. */
335		if (!(sp = getservbyname("biff", "udp")))
336			return;
337		if (!(hp = gethostbyname("localhost"))) {
338			logwarn("localhost: %s", strerror(errno));
339			return;
340		}
341		addr.sin_len = sizeof(struct sockaddr_in);
342		addr.sin_family = hp->h_addrtype;
343		addr.sin_port = sp->s_port;
344		memcpy(&addr.sin_addr, hp->h_addr, hp->h_length);
345	}
346	if (f < 0 && (f = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
347		logwarn("socket: %s", strerror(errno));
348		return;
349	}
350	len = strlen(msg) + 1;
351	if (sendto(f, msg, len, 0, (struct sockaddr *)&addr, sizeof(addr))
352	    != len)
353		logwarn("sendto biff: %s", strerror(errno));
354}
355
356static void
357usage(void)
358{
359	logerr(EX_USAGE, "usage: mail.local [-l] [-f from] user ...");
360}
361
362static void
363logerr(int status, const char *fmt, ...)
364{
365	va_list ap;
366
367	va_start(ap, fmt);
368	vsyslog(LOG_ERR, fmt, ap);
369	va_end(ap);
370
371	exit(status);
372	/* NOTREACHED */
373}
374
375static void
376logwarn(const char *fmt, ...)
377{
378	va_list ap;
379
380	va_start(ap, fmt);
381	vsyslog(LOG_ERR, fmt, ap);
382	va_end(ap);
383	return;
384}
385