98f9f1c389
Most important change being: dma - Fix security hole (#46) Affecting DragonFly 4.6 and earlier, Matt Dillon fixed this in base after finding out from BSDNow Episode 152. Comments following were from his commit which explains better than I. Just taking his change and putting it here as well. * dma makes an age-old mistake of not properly checking whether a file owned by a user is a symlink or not, a bug which the original mail.local also had. * Add O_NOFOLLOW to disallow symlinks. Thanks-to: BSDNow Episode 152, made me dive dma to check when they talked about the mail.local bug. MFC After: 2 days
161 lines
4.4 KiB
C
161 lines
4.4 KiB
C
/*
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* Copyright (c) 2010-2014, Simon Schubert <2@0x2c.org>.
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* Copyright (c) 2008 The DragonFly Project. All rights reserved.
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*
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* This code is derived from software contributed to The DragonFly Project
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* by Simon Schubert <2@0x2c.org>.
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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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*
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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
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name of The DragonFly Project nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific, prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* This binary is setuid root. Use extreme caution when touching
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* user-supplied information. Keep the root window as small as possible.
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*/
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#include <sys/param.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <grp.h>
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#include <paths.h>
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#include <pwd.h>
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#include <stdio.h>
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#include <syslog.h>
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#include <unistd.h>
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#include "dma.h"
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static void
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logfail(int exitcode, const char *fmt, ...)
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{
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int oerrno = errno;
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va_list ap;
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char outs[1024];
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outs[0] = 0;
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if (fmt != NULL) {
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va_start(ap, fmt);
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vsnprintf(outs, sizeof(outs), fmt, ap);
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va_end(ap);
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}
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errno = oerrno;
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if (*outs != 0)
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syslog(LOG_ERR, errno ? "%s: %m" : "%s", outs);
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else
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syslog(LOG_ERR, errno ? "%m" : "unknown error");
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exit(exitcode);
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}
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/*
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* Create a mbox in /var/mail for a given user, or make sure
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* the permissions are correct for dma.
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*/
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int
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main(int argc, char **argv)
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{
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const char *user;
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struct passwd *pw;
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struct group *gr;
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uid_t user_uid;
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gid_t mail_gid;
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int error;
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char fn[PATH_MAX+1];
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int f;
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openlog("dma-mbox-create", 0, LOG_MAIL);
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errno = 0;
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gr = getgrnam(DMA_GROUP);
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if (!gr)
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logfail(EX_CONFIG, "cannot find dma group `%s'", DMA_GROUP);
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mail_gid = gr->gr_gid;
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if (setgid(mail_gid) != 0)
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logfail(EX_NOPERM, "cannot set gid to %d (%s)", mail_gid, DMA_GROUP);
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if (getegid() != mail_gid)
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logfail(EX_NOPERM, "cannot set gid to %d (%s), still at %d", mail_gid, DMA_GROUP, getegid());
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/*
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* We take exactly one argument: the username.
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*/
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if (argc != 2) {
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errno = 0;
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logfail(EX_USAGE, "no arguments");
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}
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user = argv[1];
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syslog(LOG_NOTICE, "creating mbox for `%s'", user);
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/* the username may not contain a pathname separator */
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if (strchr(user, '/')) {
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errno = 0;
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logfail(EX_DATAERR, "path separator in username `%s'", user);
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exit(1);
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}
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/* verify the user exists */
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errno = 0;
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pw = getpwnam(user);
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if (!pw)
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logfail(EX_NOUSER, "cannot find user `%s'", user);
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user_uid = pw->pw_uid;
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error = snprintf(fn, sizeof(fn), "%s/%s", _PATH_MAILDIR, user);
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if (error < 0 || (size_t)error >= sizeof(fn)) {
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if (error >= 0) {
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errno = 0;
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logfail(EX_USAGE, "mbox path too long");
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}
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logfail(EX_CANTCREAT, "cannot build mbox path for `%s/%s'", _PATH_MAILDIR, user);
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}
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f = open(fn, O_RDONLY|O_CREAT|O_NOFOLLOW, 0600);
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if (f < 0)
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logfail(EX_NOINPUT, "cannt open mbox `%s'", fn);
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if (fchown(f, user_uid, mail_gid))
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logfail(EX_OSERR, "cannot change owner of mbox `%s'", fn);
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if (fchmod(f, 0620))
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logfail(EX_OSERR, "cannot change permissions of mbox `%s'", fn);
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/* file should be present with the right owner and permissions */
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syslog(LOG_NOTICE, "successfully created mbox for `%s'", user);
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return (0);
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}
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