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      1 /*	$NetBSD: mail.local.c,v 1.27 2016/07/19 13:11:38 shm 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
     37 static char sccsid[] = "@(#)mail.local.c	8.22 (Berkeley) 6/21/95";
     38 #else
     39 __RCSID("$NetBSD: mail.local.c,v 1.27 2016/07/19 13:11:38 shm 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 <stdio.h>
     55 #include <stdlib.h>
     56 #include <string.h>
     57 #include <syslog.h>
     58 #include <time.h>
     59 #include <unistd.h>
     60 #include <sysexits.h>
     61 
     62 
     63 #include "pathnames.h"
     64 
     65 static int	deliver(int, char *, int);
     66 __dead static void	logerr(int, const char *, ...) __printflike(2, 3);
     67 static void	logwarn(const char *, ...) __printflike(1, 2);
     68 static void	notifybiff(char *);
     69 static int	store(const char *);
     70 __dead static void	usage(void);
     71 
     72 int
     73 main(int argc, char *argv[])
     74 {
     75 	struct passwd *pw;
     76 	int ch, fd, eval, lockfile = 0;
     77 	uid_t uid;
     78 	const char *from;
     79 
     80 	/* use a reasonable umask */
     81 	(void) umask(0077);
     82 
     83 	openlog("mail.local", LOG_PERROR, LOG_MAIL);
     84 
     85 	from = NULL;
     86 	while ((ch = getopt(argc, argv, "ldf:r:")) != -1)
     87 		switch (ch) {
     88 		case 'd':		/* backward compatible */
     89 			break;
     90 		case 'f':
     91 		case 'r':		/* backward compatible */
     92 			if (from)
     93 				logerr(EX_USAGE, "multiple -f options");
     94 			from = optarg;
     95 			break;
     96 		case 'l':
     97 			lockfile++;
     98 			break;
     99 		case '?':
    100 		default:
    101 			usage();
    102 		}
    103 	argc -= optind;
    104 	argv += optind;
    105 
    106 	if (!*argv)
    107 		usage();
    108 
    109 	/*
    110 	 * If from not specified, use the name from getlogin() if the
    111 	 * uid matches, otherwise, use the name from the password file
    112 	 * corresponding to the uid.
    113 	 */
    114 	uid = getuid();
    115 	if (!from && (!(from = getlogin()) ||
    116 	    !(pw = getpwnam(from)) || pw->pw_uid != uid))
    117 		from = (pw = getpwuid(uid)) ? pw->pw_name : "???";
    118 
    119 	fd = store(from);
    120 	for (eval = EX_OK; *argv; ++argv) {
    121 		int rval;
    122 
    123 		rval = deliver(fd, *argv, lockfile);
    124 		if (eval == EX_OK && rval != EX_OK)
    125 			eval = rval;
    126 	}
    127 	exit (eval);
    128 }
    129 
    130 static int
    131 store(const char *from)
    132 {
    133 	FILE *fp = NULL;	/* XXX gcc */
    134 	time_t tval;
    135 	int fd, eline;
    136 	char *tn, line[2048];
    137 
    138 	tn = strdup(_PATH_LOCTMP);
    139 	if (!tn)
    140 		logerr(EX_OSERR, "not enough core");
    141 	if ((fd = mkstemp(tn)) == -1 || !(fp = fdopen(fd, "w+")))
    142 		logerr(EX_OSERR, "unable to open temporary file");
    143 	(void)unlink(tn);
    144 	free(tn);
    145 
    146 	(void)time(&tval);
    147 	(void)fprintf(fp, "From %s %s", from, ctime(&tval));
    148 
    149 	line[0] = '\0';
    150 	for (eline = 1; fgets(line, sizeof(line), stdin);) {
    151 		if (line[0] == '\n')
    152 			eline = 1;
    153 		else {
    154 			if (eline && line[0] == 'F' && !memcmp(line, "From ", 5))
    155 				(void)putc('>', fp);
    156 			eline = 0;
    157 		}
    158 		(void)fprintf(fp, "%s", line);
    159 		if (ferror(fp))
    160 			break;
    161 	}
    162 
    163 	/* If message not newline terminated, need an extra. */
    164 	if (!index(line, '\n'))
    165 		(void)putc('\n', fp);
    166 	/* Output a newline; note, empty messages are allowed. */
    167 	(void)putc('\n', fp);
    168 
    169 	(void)fflush(fp);
    170 	if (ferror(fp))
    171 		logerr(EX_OSERR, "temporary file write error");
    172 	if ((fd = dup(fd)) == -1)
    173 		logerr(EX_OSERR, "dup failed");
    174 	(void)fclose(fp);
    175 	return(fd);
    176 }
    177 
    178 static int
    179 deliver(int fd, char *name, int lockfile)
    180 {
    181 	struct stat sb, nsb;
    182 	struct passwd pwres, *pw;
    183 	char pwbuf[1024];
    184 	int created = 0, mbfd, nr, nw, off, rval=EX_OK, lfd = -1;
    185 	char biffmsg[100], buf[8*1024], path[MAXPATHLEN], lpath[MAXPATHLEN];
    186 	off_t curoff;
    187 
    188 	/*
    189 	 * Disallow delivery to unknown names -- special mailboxes can be
    190 	 * handled in the sendmail aliases file.
    191 	 */
    192 	if ((getpwnam_r(name, &pwres, pwbuf, sizeof(pwbuf), &pw)) != 0) {
    193 		logwarn("unable to find user %s: %s", name, strerror(errno));
    194 		return(EX_TEMPFAIL);
    195 	}
    196 	if (pw == NULL) {
    197 		logwarn("unknown name: %s", name);
    198 		return(EX_NOUSER);
    199 	}
    200 
    201 	(void)snprintf(path, sizeof path, "%s/%s", _PATH_MAILDIR, name);
    202 
    203 	if (lockfile) {
    204 		(void)snprintf(lpath, sizeof lpath, "%s/%s.lock",
    205 		    _PATH_MAILDIR, name);
    206 
    207 		if((lfd = open(lpath, O_CREAT|O_WRONLY|O_EXCL,
    208 		    S_IRUSR|S_IWUSR)) < 0) {
    209 			logwarn("%s: %s", lpath, strerror(errno));
    210 			return(EX_OSERR);
    211 		}
    212 	}
    213 
    214 	if ((lstat(path, &sb) != -1) &&
    215 	    (sb.st_nlink != 1 || S_ISLNK(sb.st_mode))) {
    216 		logwarn("%s: linked file", path);
    217 		return(EX_OSERR);
    218 	}
    219 
    220 	if ((mbfd = open(path, O_APPEND|O_WRONLY|O_EXLOCK,
    221 	    S_IRUSR|S_IWUSR)) == -1) {
    222 		/* create file */
    223 		if ((mbfd = open(path, O_APPEND|O_CREAT|O_WRONLY|O_EXLOCK,
    224 		    S_IRUSR|S_IWUSR)) == -1) {
    225 			logwarn("%s: %s", path, strerror(errno));
    226 			rval = EX_OSERR;
    227 			goto bad;
    228 		}
    229 		created = 1;
    230 	} else {
    231 		/* opened existing file, check for TOCTTOU */
    232 		if (fstat(mbfd, &nsb) == -1) {
    233 			rval = EX_OSERR;
    234 			goto bad;
    235 		}
    236 
    237 		/* file is not what we expected */
    238 		if (nsb.st_ino != sb.st_ino || nsb.st_dev != sb.st_dev) {
    239 			rval = EX_OSERR;
    240 			goto bad;
    241 		}
    242 	}
    243 
    244 	if ((curoff = lseek(mbfd, 0, SEEK_END)) == (off_t)-1) {
    245 		logwarn("%s: %s", path, strerror(errno));
    246 		rval = EX_OSERR;
    247 		goto bad;
    248 	}
    249 
    250 	(void)snprintf(biffmsg, sizeof biffmsg, "%s@%lld\n", name,
    251 	    (long long)curoff);
    252 	if (lseek(fd, 0, SEEK_SET) == (off_t)-1) {
    253 		logwarn("temporary file: %s", strerror(errno));
    254 		rval = EX_OSERR;
    255 		goto bad;
    256 	}
    257 
    258 	while ((nr = read(fd, buf, sizeof(buf))) > 0)
    259 		for (off = 0; off < nr;  off += nw)
    260 			if ((nw = write(mbfd, buf + off, nr - off)) < 0) {
    261 				logwarn("%s: %s", path, strerror(errno));
    262 				goto trunc;
    263 			}
    264 	if (nr < 0) {
    265 		logwarn("temporary file: %s", strerror(errno));
    266 trunc:		(void)ftruncate(mbfd, curoff);
    267 		rval = EX_OSERR;
    268 	}
    269 
    270 	/*
    271 	 * Set the owner and group.  Historically, binmail repeated this at
    272 	 * each mail delivery.  We no longer do this, assuming that if the
    273 	 * ownership or permissions were changed there was a reason for doing
    274 	 * so.
    275 	 */
    276 bad:
    277 	if (lockfile) {
    278 		if (lfd >= 0) {
    279 			unlink(lpath);
    280 			close(lfd);
    281 		}
    282 	}
    283 
    284 	if (mbfd >= 0) {
    285 		if (created)
    286 			(void)fchown(mbfd, pw->pw_uid, pw->pw_gid);
    287 
    288 		(void)fsync(mbfd);		/* Don't wait for update. */
    289 		(void)close(mbfd);		/* Implicit unlock. */
    290 	}
    291 
    292 	if (rval == EX_OK)
    293 		notifybiff(biffmsg);
    294 
    295 	return rval;
    296 }
    297 
    298 void
    299 notifybiff(char *msg)
    300 {
    301 	static struct sockaddr_in addr;
    302 	static int f = -1;
    303 	struct hostent *hp;
    304 	struct servent *sp;
    305 	int len;
    306 
    307 	if (!addr.sin_family) {
    308 		/* Be silent if biff service not available. */
    309 		if (!(sp = getservbyname("biff", "udp")))
    310 			return;
    311 		if (!(hp = gethostbyname("localhost"))) {
    312 			logwarn("localhost: %s", strerror(errno));
    313 			return;
    314 		}
    315 		addr.sin_len = sizeof(struct sockaddr_in);
    316 		addr.sin_family = hp->h_addrtype;
    317 		addr.sin_port = sp->s_port;
    318 		memcpy(&addr.sin_addr, hp->h_addr, hp->h_length);
    319 	}
    320 	if (f < 0 && (f = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
    321 		logwarn("socket: %s", strerror(errno));
    322 		return;
    323 	}
    324 	len = strlen(msg) + 1;
    325 	if (sendto(f, msg, len, 0, (struct sockaddr *)&addr, sizeof(addr))
    326 	    != len)
    327 		logwarn("sendto biff: %s", strerror(errno));
    328 }
    329 
    330 static void
    331 usage(void)
    332 {
    333 	logerr(EX_USAGE, "usage: mail.local [-l] [-f from] user ...");
    334 }
    335 
    336 static void
    337 logerr(int status, const char *fmt, ...)
    338 {
    339 	va_list ap;
    340 
    341 	va_start(ap, fmt);
    342 	vsyslog(LOG_ERR, fmt, ap);
    343 	va_end(ap);
    344 
    345 	exit(status);
    346 	/* NOTREACHED */
    347 }
    348 
    349 static void
    350 logwarn(const char *fmt, ...)
    351 {
    352 	va_list ap;
    353 
    354 	va_start(ap, fmt);
    355 	vsyslog(LOG_ERR, fmt, ap);
    356 	va_end(ap);
    357 	return;
    358 }
    359