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/*
* Copyright (c) 2010 Simon Schubert <2@0x2c.org>
* Copyright (c) 2008 The DragonFly Project. All rights reserved.
*
* This code is derived from software contributed to The DragonFly Project
* by Simon 'corecode' Schubert <corecode@fs.ei.tum.de>.
*
* 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. Neither the name of The DragonFly Project 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 COPYRIGHT HOLDERS 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
* COPYRIGHT HOLDERS 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.
*/

/*
* This binary is setuid root. Use extreme caution when touching
* user-supplied information. Keep the root window as small as possible.
*/

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

#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <paths.h>
#include <pwd.h>
#include <stdio.h>
#include <syslog.h>
#include <unistd.h>

#include "dma.h"


static void
logfail(const char *fmt, ...)
{
int oerrno = errno;
va_list ap;
char outs[1024];

outs[0] = 0;
if (fmt != NULL) {
va_start(ap, fmt);
vsnprintf(outs, sizeof(outs), fmt, ap);
va_end(ap);
}

errno = oerrno;
if (*outs != 0)
syslog(LOG_ERR, errno ? "%s: %m" : "%s", outs);
else
syslog(LOG_ERR, errno ? "%m" : "unknown error");

exit(1);
}

/*
* Create a mbox in /var/mail for a given user, or make sure
* the permissions are correct for dma.
*/

int
main(int argc, char **argv)
{
const char *user;
struct passwd *pw;
struct group *gr;
uid_t user_uid;
gid_t mail_gid;
int error;
char fn[PATH_MAX+1];
int f;

openlog("dma-mbox-create", 0, LOG_MAIL);

errno = 0;
gr = getgrnam(DMA_GROUP);
if (!gr)
logfail("cannot find dma group `%s'", DMA_GROUP);

mail_gid = gr->gr_gid;

if (setgid(mail_gid) != 0)
logfail("cannot set gid to %d (%s)", mail_gid, DMA_GROUP);
if (getegid() != mail_gid)
logfail("cannot set gid to %d (%s), still at %d", mail_gid, DMA_GROUP, getegid());

/*
* We take exactly one argument: the username.
*/
if (argc != 2) {
errno = 0;
logfail("no arguments");
}
user = argv[1];

syslog(LOG_NOTICE, "creating mbox for `%s'", user);

/* the username may not contain a pathname separator */
if (strchr(user, '/')) {
errno = 0;
logfail("path separator in username `%s'", user);
exit(1);
}

/* verify the user exists */
errno = 0;
pw = getpwnam(user);
if (!pw)
logfail("cannot find user `%s'", user);

user_uid = pw->pw_uid;

error = snprintf(fn, sizeof(fn), "%s/%s", _PATH_MAILDIR, user);
if (error < 0 || (size_t)error >= sizeof(fn)) {
if (error >= 0) {
errno = 0;
logfail("mbox path too long");
}
logfail("cannot build mbox path for `%s/%s'", _PATH_MAILDIR, user);
}

f = open(fn, O_RDONLY|O_CREAT, 0600);
if (f < 0)
logfail("cannot open mbox `%s'", fn);

if (fchown(f, user_uid, mail_gid))
logfail("cannot change owner of mbox `%s'", fn);

if (fchmod(f, 0620))
logfail("cannot change permissions of mbox `%s'", fn);

/* file should be present with the right owner and permissions */

syslog(LOG_NOTICE, "successfully created mbox for `%s'", user);

return (0);
}
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