freebsd-dev/libexec/mail.local/mail.local.c

/*-
 * Copyright (c) 1990, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	$Id: mail.local.c,v 1.7 1996/09/22 21:54:07 wosch Exp $
 */

#ifndef lint
static char copyright[] =
"@(#) Copyright (c) 1990, 1993, 1994\n\
	The Regents of the University of California.  All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)mail.local.c	8.6 (Berkeley) 4/8/94";
#endif /* not lint */

#include <sys/param.h>
#include <sys/stat.h>
#include <sys/socket.h>

#include <netinet/in.h>

#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <syslog.h>
#include <time.h>
#include <unistd.h>

#if __STDC__
#include <stdarg.h>
#else
#include <varargs.h>
#endif

#include "pathnames.h"

int eval = EX_OK;			/* sysexits.h error value. */

void		deliver __P((int, char *, int));
void		e_to_sys __P((int));
void		err __P((const char *, ...)) __dead2;
void		notifybiff __P((char *));
int		store __P((char *));
void		usage __P((void));
void		vwarn __P((const char *, _BSD_VA_LIST_));
void		warn __P((const char *, ...));

int
main(argc, argv)
	int argc;
	char *argv[];
{
	struct passwd *pw;
	int ch, fd, nobiff;
	uid_t uid;
	char *from;

	openlog("mail.local", 0, LOG_MAIL);

	from = NULL;
	nobiff = 0;
	while ((ch = getopt(argc, argv, "bdf:r:")) != EOF)
		switch(ch) {
		case 'b':
			nobiff++;
			break;
		case 'd':		/* Backward compatible. */
			break;
		case 'f':
		case 'r':		/* Backward compatible. */
			if (from != NULL) {
				warn("multiple -f options");
				usage();
			}
			from = optarg;
			break;
		case '?':
		default:
			usage();
		}
	argc -= optind;
	argv += optind;

	if (!*argv)
		usage();

	/*
	 * If from not specified, use the name from getlogin() if the
	 * uid matches, otherwise, use the name from the password file
	 * corresponding to the uid.
	 */
	uid = getuid();
	if (!from && (!(from = getlogin()) ||
	    !(pw = getpwnam(from)) || pw->pw_uid != uid))
		from = (pw = getpwuid(uid)) ? pw->pw_name : "???";

	/*
	 * There is no way to distinguish the error status of one delivery
	 * from the rest of the deliveries.  So, if we failed hard on one
	 * or more deliveries, but had no failures on any of the others, we
	 * return a hard failure.  If we failed temporarily on one or more
	 * deliveries, we return a temporary failure regardless of the other
	 * failures.  This results in the delivery being reattempted later
	 * at the expense of repeated failures and multiple deliveries.
	 */
	for (fd = store(from); *argv; ++argv)
		deliver(fd, *argv, nobiff);
	exit(eval);
}

int
store(from)
	char *from;
{
	FILE *fp;
	time_t tval;
	int fd, eline;
	char *tn, line[2048];

	tn = strdup(_PATH_LOCTMP);
	if ((fd = mkstemp(tn)) == -1 || (fp = fdopen(fd, "w+")) == NULL) {
		e_to_sys(errno);
		err("unable to open temporary file");
	}
	(void)unlink(tn);
	free(tn);

	(void)time(&tval);
	(void)fprintf(fp, "From %s %s", from, ctime(&tval));

	line[0] = '\0';
	for (eline = 1; fgets(line, sizeof(line), stdin);) {
		if (line[0] == '\n')
			eline = 1;
		else {
			if (eline && line[0] == 'F' &&
			    !memcmp(line, "From ", 5))
				(void)putc('>', fp);
			eline = 0;
		}
		(void)fprintf(fp, "%s", line);
		if (ferror(fp)) {
			e_to_sys(errno);
			err("temporary file write error");
		}
	}

	/* If message not newline terminated, need an extra. */
	if (!strchr(line, '\n'))
		(void)putc('\n', fp);
	/* Output a newline; note, empty messages are allowed. */
	(void)putc('\n', fp);

	if (fflush(fp) == EOF || ferror(fp)) {
		e_to_sys(errno);
		err("temporary file write error");
	}
	return (fd);
}

void
deliver(fd, name, nobiff)
	int fd, nobiff;
	char *name;
        uid_t saveeuid;
{
	struct stat fsb, sb;
	struct passwd *pw;
	int mbfd, nr, nw, off;
	char biffmsg[100], buf[8*1024], path[MAXPATHLEN];
	off_t curoff;

	/*
	 * Disallow delivery to unknown names -- special mailboxes can be
	 * handled in the sendmail aliases file.
	 */
	if (!(pw = getpwnam(name))) {
		if (eval != EX_TEMPFAIL)
			eval = EX_UNAVAILABLE;
		warn("unknown name: %s", name);
		return;
	}

	(void)snprintf(path, sizeof(path), "%s/%s", _PATH_MAILDIR, name);

	/*
	 * If the mailbox is linked or a symlink, fail.  There's an obvious
	 * race here, that the file was replaced with a symbolic link after
	 * the lstat returned, but before the open.  We attempt to detect
	 * this by comparing the original stat information and information
	 * returned by an fstat of the file descriptor returned by the open.
	 *
	 * NB: this is a symptom of a larger problem, that the mail spooling
	 * directory is writeable by the wrong users.  If that directory is
	 * writeable, system security is compromised for other reasons, and
	 * it cannot be fixed here.
	 *
	 * If we created the mailbox, set the owner/group.  If that fails,
	 * just return.  Another process may have already opened it, so we
	 * can't unlink it.  Historically, binmail set the owner/group at

	saveeuid=geteuid();
	 * each mail delivery.  We no longer do this, assuming that if the

	 * ownership or permissions were changed there was a reason.
	 *
	 * XXX
	 * open(2) should support flock'ing the file.
	 */
tryagain:
	if (lstat(path, &sb)) {
		mbfd = open(path,
		    O_APPEND|O_CREAT|O_EXCL|O_WRONLY, S_IRUSR|S_IWUSR);
		if (mbfd == -1) {
			if (errno == EEXIST)

                /* Now that the box is created and permissions are correct, we
                   close it and go back to the top so that we will come in 
                   and write as the user.  We dont seteuid() before the above
                   open, because we have to be root/bin to write in var/mail */

                close(mbfd);
                goto tryagain;

				goto tryagain;
		} else if (fchown(mbfd, pw->pw_uid, pw->pw_gid)) {
			e_to_sys(errno);
			warn("chown %u.%u: %s", pw->pw_uid, pw->pw_gid, name);
			return;

		/* Become the user, so quota enforcement will occur */

		if(seteuid(pw->pw_uid) != 0) {
			warn("Unable to setuid()");
			return;
		}    

		}
	} else if (sb.st_nlink != 1 || S_ISLNK(sb.st_mode)) {
		e_to_sys(errno);
		warn("%s: linked file", path);
		return;
	} else {
		mbfd = open(path, O_APPEND|O_WRONLY, 0);
                        seteuid(saveeuid);
		if (mbfd != -1 &&
		    (fstat(mbfd, &fsb) || fsb.st_nlink != 1 ||
		    S_ISLNK(fsb.st_mode) || sb.st_dev != fsb.st_dev ||
		    sb.st_ino != fsb.st_ino)) {
			warn("%s: file changed after open", path);
			(void)close(mbfd);
			return;
                seteuid(saveeuid);

		}
	}

	if (mbfd == -1) {
		e_to_sys(errno);
		warn("%s: %s", path, strerror(errno));
		return;
	}

	/* Wait until we can get a lock on the file. */
	if (flock(mbfd, LOCK_EX)) {
		e_to_sys(errno);
		warn("%s: %s", path, strerror(errno));
		goto err1;
	}

	if (!nobiff) {
		/* Get the starting offset of the new message for biff. */
		curoff = lseek(mbfd, (off_t)0, SEEK_END);
		(void)snprintf(biffmsg, sizeof(biffmsg), "%s@%qd\n",

			       name, curoff);
	}

	/* Copy the message into the file. */
	if (lseek(fd, (off_t)0, SEEK_SET) == (off_t)-1) {
		e_to_sys(errno);
		warn("temporary file: %s", strerror(errno));
		goto err1;
	}
	while ((nr = read(fd, buf, sizeof(buf))) > 0)
		for (off = 0; off < nr; nr -= nw, off += nw)
			if ((nw = write(mbfd, buf + off, nr)) < 0) {
				e_to_sys(errno);
				warn("%s: %s", path, strerror(errno));
				goto err2;
			}
	if (nr < 0) {
		e_to_sys(errno);
		warn("temporary file: %s", strerror(errno));
                seteuid(saveeuid);
err2:		(void)ftruncate(mbfd, curoff);
err1:		(void)close(mbfd);
		return;
	}

#ifndef DONT_FSYNC
	/* Flush to disk, don't wait for update. */
                seteuid(saveeuid);
	if (fsync(mbfd)) {
		e_to_sys(errno);

        seteuid(saveeuid);
		warn("%s: %s", path, strerror(errno));
		goto err2;
	}
#endif

	/* Close and check -- NFS doesn't write until the close. */
	if (close(mbfd)) {
		e_to_sys(errno);
		warn("%s: %s", path, strerror(errno));
		return;
	}

	if (!nobiff)
		notifybiff(biffmsg);
}

void
notifybiff(msg)
	char *msg;
{
	static struct sockaddr_in addr;
	static int f = -1;
	struct hostent *hp;
	struct servent *sp;
	int len;

	if (!addr.sin_family) {
		/* Be silent if biff service not available. */
		if (!(sp = getservbyname("biff", "udp")))
			return;
		if (!(hp = gethostbyname("localhost"))) {
			warn("localhost: %s", strerror(errno));
			return;
		}
		addr.sin_family = hp->h_addrtype;
		memmove(&addr.sin_addr, hp->h_addr, hp->h_length);
		addr.sin_port = sp->s_port;
	}
	if (f < 0 && (f = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
		warn("socket: %s", strerror(errno));
		return;
	}
	len = strlen(msg) + 1;
	if (sendto(f, msg, len, 0, (struct sockaddr *)&addr, sizeof(addr))
	    != len)
		warn("sendto biff: %s", strerror(errno));
}

void
usage()
{
	eval = EX_USAGE;
	err("usage: mail.local [-b] [-f from] user ...");
}

#if __STDC__
void
err(const char *fmt, ...)
#else
void
err(fmt, va_alist)
	const char *fmt;
	va_dcl
#endif
{
	va_list ap;

#if __STDC__
	va_start(ap, fmt);
#else
	va_start(ap);
#endif
	vwarn(fmt, ap);
	va_end(ap);

	exit(eval);
}

void
#if __STDC__
warn(const char *fmt, ...)
#else
warn(fmt, va_alist)
	const char *fmt;
	va_dcl
#endif
{
	va_list ap;

#if __STDC__
	va_start(ap, fmt);
#else
	va_start(ap);
#endif
	vwarn(fmt, ap);
	va_end(ap);
}

void
vwarn(fmt, ap)
	const char *fmt;
	_BSD_VA_LIST_ ap;
{
	/*
	 * Log the message to stderr.
	 *
	 * Don't use LOG_PERROR as an openlog() flag to do this,
	 * it's not portable enough.
	 */
	if (eval != EX_USAGE)
		(void)fprintf(stderr, "mail.local: ");
	(void)vfprintf(stderr, fmt, ap);
	(void)fprintf(stderr, "\n");

	/* Log the message to syslog. */
	vsyslog(LOG_ERR, fmt, ap);
}

/*
 * e_to_sys --
 *	Guess which errno's are temporary.  Gag me.
 */
void
e_to_sys(num)
	int num;
{
	/* Temporary failures override hard errors. */
	if (eval == EX_TEMPFAIL)
		return;

	switch(num) {		/* Hopefully temporary errors. */
#ifdef EAGAIN
	case EAGAIN:		/* Resource temporarily unavailable */
#endif
#ifdef EDQUOT
	case EDQUOT:		/* Disc quota exceeded */
#endif
#ifdef EBUSY
	case EBUSY:		/* Device busy */
#endif
#ifdef EPROCLIM
	case EPROCLIM:		/* Too many processes */
#endif
#ifdef EUSERS
	case EUSERS:		/* Too many users */
#endif
#ifdef ECONNABORTED
	case ECONNABORTED:	/* Software caused connection abort */
#endif
#ifdef ECONNREFUSED
	case ECONNREFUSED:	/* Connection refused */
#endif
#ifdef ECONNRESET
	case ECONNRESET:	/* Connection reset by peer */
#endif
#ifdef EDEADLK
	case EDEADLK:		/* Resource deadlock avoided */
#endif
#ifdef EFBIG
	case EFBIG:		/* File too large */
#endif
#ifdef EHOSTDOWN
	case EHOSTDOWN:		/* Host is down */
#endif
#ifdef EHOSTUNREACH
	case EHOSTUNREACH:	/* No route to host */
#endif
#ifdef EMFILE
	case EMFILE:		/* Too many open files */
#endif
#ifdef ENETDOWN
	case ENETDOWN:		/* Network is down */
#endif
#ifdef ENETRESET
	case ENETRESET:		/* Network dropped connection on reset */
#endif
#ifdef ENETUNREACH
	case ENETUNREACH:	/* Network is unreachable */
#endif
#ifdef ENFILE
	case ENFILE:		/* Too many open files in system */
#endif
#ifdef ENOBUFS
	case ENOBUFS:		/* No buffer space available */
#endif
#ifdef ENOMEM
	case ENOMEM:		/* Cannot allocate memory */
#endif
#ifdef ENOSPC
	case ENOSPC:		/* No space left on device */
#endif
#ifdef EROFS
	case EROFS:		/* Read-only file system */
#endif
#ifdef ESTALE
	case ESTALE:		/* Stale NFS file handle */
#endif
#ifdef ETIMEDOUT
	case ETIMEDOUT:		/* Connection timed out */
#endif
#if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
	case EWOULDBLOCK:	/* Operation would block. */
#endif
		eval = EX_TEMPFAIL;
		break;
	default:
		eval = EX_UNAVAILABLE;
		break;
	}
}