NetBSD/sbin/mount_portal/pt_file.c

198 lines
5.8 KiB
C

/* $NetBSD: pt_file.c,v 1.15 2003/08/07 10:04:30 agc Exp $ */
/*
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software donated to Berkeley by
* Jan-Simon Pendry.
*
* 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 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.
*
* from: Id: pt_file.c,v 1.1 1992/05/25 21:43:09 jsp Exp
* @(#)pt_file.c 8.3 (Berkeley) 7/3/94
*/
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: pt_file.c,v 1.15 2003/08/07 10:04:30 agc Exp $");
#endif /* not lint */
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/syslog.h>
#include "portald.h"
#ifdef DEBUG
#define DEBUG_SYSLOG syslog
#else
/*
* The "if (0) ..." will be optimized away by the compiler if
* DEBUG is not defined.
*/
#define DEBUG_SYSLOG if (0) syslog
#endif
int
lose_credentials(pcr)
struct portal_cred *pcr;
{
/*
* If we are root, then switch into the caller's credentials.
* By the way, we _always_ log failures, to make
* sure questionable activity is noticed.
*/
if (getuid() == 0) {
/* Set groups first ... */
if (setgroups(pcr->pcr_ngroups, pcr->pcr_groups) < 0) {
syslog(LOG_WARNING,
"lose_credentials: setgroups() failed (%m)");
return (errno);
}
/* ... then gid ... */
if (setgid(pcr->pcr_gid) < 0) {
syslog(LOG_WARNING,
"lose_credentials: setgid(%d) failed (%m)",
pcr->pcr_gid);
}
/*
* ... and now do the setuid() where we lose all special
* powers (both real and effective userid).
*/
if (setuid(pcr->pcr_uid) < 0) {
syslog(LOG_WARNING,
"lose_credentials: setuid(%d) failed (%m)",
pcr->pcr_uid);
}
/* The credential change was successful! */
DEBUG_SYSLOG(LOG_DEBUG, "Root-owned mount process lowered credentials -- returning successfully!\n");
return 0;
}
DEBUG_SYSLOG(LOG_DEBUG, "Actual/effective/caller's creds are:");
DEBUG_SYSLOG(LOG_DEBUG, "%d/%d %d/%d %d/%d", getuid(),
getgid(), geteuid(), getegid(), pcr->pcr_uid, pcr->pcr_gid);
/*
* Else, fail if the uid is neither actual or effective
* uid of mount process...
*/
if ((getuid() != pcr->pcr_uid) && (geteuid() != pcr->pcr_uid)) {
syslog(LOG_WARNING,
"lose_credentials: uid %d != uid %d, or euid %d != uid %d",
getuid(), pcr->pcr_uid, geteuid(), pcr->pcr_uid);
return EPERM;
}
/*
* ... or the gid is neither the actual or effective
* gid of the mount process.
*/
if ((getgid() != pcr->pcr_gid) && (getegid() != pcr->pcr_gid)) {
syslog(LOG_WARNING,
"lose_credentials: gid %d != gid %d, or egid %d != gid %d",
getgid(), pcr->pcr_gid, getegid(), pcr->pcr_gid);
return EPERM;
}
/*
* If we make it here, we have a uid _and_ gid match! Allow the
* access.
*/
DEBUG_SYSLOG(LOG_DEBUG, "Returning successfully!\n");
return 0;
}
int
portal_file(pcr, key, v, so, fdp)
struct portal_cred *pcr;
char *key;
char **v;
int so;
int *fdp;
{
int fd;
char pbuf[MAXPATHLEN];
int error;
int origuid, origgid;
origuid = getuid();
origgid = getgid();
pbuf[0] = '/';
strlcpy(pbuf + 1, key + (v[1] ? strlen(v[1]) : 0), sizeof(pbuf) - 1);
DEBUG_SYSLOG(LOG_DEBUG, "path = %s, uid = %d, gid = %d",
pbuf, pcr->pcr_uid, pcr->pcr_gid);
if ((error = lose_credentials(pcr)) != 0) {
DEBUG_SYSLOG(LOG_DEBUG, "portal_file: Credential err %d", error);
return error;
}
error = 0;
/*
* Be careful -- only set error to errno if there is an error.
* errno could hold an old, uncaught value, from a routine
* called long before now.
*/
fd = open(pbuf, O_RDWR | O_CREAT, 0666);
if (fd < 0) {
error = errno;
if (error == EACCES) {
DEBUG_SYSLOG(LOG_DEBUG, "Error: could not open '%s' "
"read/write with create flag. "
"Trying read-only open...", pbuf);
/* Try opening read-only. */
fd = open(pbuf, O_RDONLY, 0);
if (fd < 0) {
error = errno;
DEBUG_SYSLOG(LOG_DEBUG, "That failed too! %m");
} else {
/* Clear the error indicator. */
error = 0;
}
} else {
DEBUG_SYSLOG(LOG_DEBUG, "Error: could not open '%s': %m", pbuf);
}
}
if (seteuid((uid_t) origuid) < 0) { /* XXX - should reset gidset
* too */
error = errno;
syslog(LOG_WARNING, "setcred: %m");
if (fd >= 0) {
(void) close(fd);
fd = -1;
}
}
if (error == 0)
*fdp = fd;
DEBUG_SYSLOG(LOG_DEBUG, "pt_file returns *fdp = %d, error = %d", *fdp,
error);
return (error);
}