GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: libexec/mail.local/locking.c Lines: 0 65 0.0 %
Date: 2017-11-13 Branches: 0 46 0.0 %

Line Branch Exec Source
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/*	$OpenBSD: locking.c,v 1.12 2015/01/16 06:39:50 deraadt Exp $	*/
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/*
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 * Copyright (c) 1996-1998 Theo de Raadt <deraadt@theos.com>
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 * Copyright (c) 1996-1998 David Mazieres <dm@lcs.mit.edu>
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
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 *    documentation and/or other materials provided with the distribution.
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 * 3. The name of the authors may not be used to endorse or promote products
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 *    derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
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 * THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <pwd.h>
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#include <syslog.h>
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#include <time.h>
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#include <unistd.h>
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#include <limits.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdarg.h>
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#include "pathnames.h"
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#include "mail.local.h"
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static char lpath[PATH_MAX];
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void
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rellock(void)
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{
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	if (lpath[0])
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		unlink(lpath);
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}
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int
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getlock(char *name, struct passwd *pw)
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{
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	struct stat sb, fsb;
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	int lfd=-1;
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	char buf[8*1024];
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	int tries = 0;
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	(void)snprintf(lpath, sizeof lpath, "%s/%s.lock",
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	    _PATH_MAILDIR, name);
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	if (stat(_PATH_MAILDIR, &sb) != -1 &&
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	    (sb.st_mode & S_IWOTH) == S_IWOTH) {
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		/*
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		 * We have a writeable spool, deal with it as
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		 * securely as possible.
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		 */
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		time_t ctim = -1;
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		seteuid(pw->pw_uid);
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		if (lstat(lpath, &sb) != -1)
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			ctim = sb.st_ctime;
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		while (1) {
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			/*
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			 * Deal with existing user.lock files
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			 * or directories or symbolic links that
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			 * should not be here.
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			 */
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			if (readlink(lpath, buf, sizeof buf-1) != -1) {
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				if (lstat(lpath, &sb) != -1 &&
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				    S_ISLNK(sb.st_mode)) {
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					seteuid(sb.st_uid);
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					unlink(lpath);
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					seteuid(pw->pw_uid);
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				}
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				goto again;
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			}
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			if ((lfd = open(lpath, O_CREAT|O_WRONLY|O_EXCL|O_EXLOCK,
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			    S_IRUSR|S_IWUSR)) != -1)
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				break;
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again:
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			if (tries > 10) {
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				merr(NOTFATAL, "%s: %s", lpath,
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				    strerror(errno));
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				seteuid(0);
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				return(-1);
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			}
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			if (tries > 9 &&
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			    (lfd = open(lpath, O_WRONLY|O_EXLOCK, 0)) != -1) {
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				if (fstat(lfd, &fsb) != -1 &&
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				    lstat(lpath, &sb) != -1) {
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					if (fsb.st_dev == sb.st_dev &&
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					    fsb.st_ino == sb.st_ino &&
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					    ctim == fsb.st_ctime ) {
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						seteuid(fsb.st_uid);
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						baditem(lpath);
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						seteuid(pw->pw_uid);
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					}
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				}
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				close(lfd);
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			}
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			sleep(1U << tries);
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			tries++;
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			continue;
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		}
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		seteuid(0);
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	} else {
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		/*
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		 * Only root can write the spool directory.
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		 */
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		while (1) {
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			if ((lfd = open(lpath, O_CREAT|O_WRONLY|O_EXCL,
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			    S_IRUSR|S_IWUSR)) != -1)
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				break;
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			if (tries > 9) {
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				merr(NOTFATAL, "%s: %s", lpath, strerror(errno));
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				return(-1);
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			}
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			sleep(1U << tries);
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			tries++;
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		}
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	}
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	return(lfd);
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}
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void
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baditem(char *path)
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{
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	char npath[PATH_MAX];
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	int fd;
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	if (unlink(path) == 0)
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		return;
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	snprintf(npath, sizeof npath, "%s/mailXXXXXXXXXX", _PATH_MAILDIR);
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	if ((fd = mkstemp(npath)) == -1)
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		return;
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	close(fd);
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	if (rename(path, npath) == -1)
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		unlink(npath);
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	else
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		merr(NOTFATAL, "nasty spool item %s renamed to %s",
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		    path, npath);
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	/* XXX if we fail to rename, another attempt will happen later */
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}
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void
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merr(int isfatal, const char *fmt, ...)
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{
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	va_list ap;
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	va_start(ap, fmt);
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	vsyslog(LOG_ERR, fmt, ap);
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	va_end(ap);
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	if (isfatal)
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		exit(1);
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}