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/*-
* Copyright (c) 2002-2003 Networks Associates Technology, Inc.
* Copyright (c) 2004-2007 Dag-Erling Smørgrav
* All rights reserved.
*
* This software was developed for the FreeBSD Project by ThinkSec AS and
* Network Associates Laboratories, the Security Research Division of
* Network Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035
* ("CBOSS"), as part of the DARPA CHATS research program.
*
* 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. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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: openpam_borrow_cred.c 408 2007-12-21 11:36:24Z des $
*/
#include <sys/param.h>
#include <grp.h>
#include <limits.h>
#include <pwd.h>
#include <stdlib.h>
#include <unistd.h>
#include <security/pam_appl.h>
#include "openpam_impl.h"
/*
* OpenPAM extension
*
* Temporarily borrow user credentials
*/
int
openpam_borrow_cred(pam_handle_t *pamh,
const struct passwd *pwd)
{
struct pam_saved_cred *scred;
const void *scredp;
int r;
ENTERI(pwd->pw_uid);
r = pam_get_data(pamh, PAM_SAVED_CRED, &scredp);
if (r == PAM_SUCCESS && scredp != NULL) {
openpam_log(PAM_LOG_DEBUG,
"already operating under borrowed credentials");
RETURNC(PAM_SYSTEM_ERR);
}
if (geteuid() != 0 && geteuid() != pwd->pw_uid) {
openpam_log(PAM_LOG_DEBUG, "called with non-zero euid: %d",
(int)geteuid());
RETURNC(PAM_PERM_DENIED);
}
scred = calloc(1, sizeof *scred);
if (scred == NULL)
RETURNC(PAM_BUF_ERR);
scred->euid = geteuid();
scred->egid = getegid();
r = getgroups(NGROUPS_MAX, scred->groups);
if (r < 0) {
FREE(scred);
RETURNC(PAM_SYSTEM_ERR);
}
scred->ngroups = r;
r = pam_set_data(pamh, PAM_SAVED_CRED, scred, &openpam_free_data);
if (r != PAM_SUCCESS) {
FREE(scred);
RETURNC(r);
}
if (geteuid() == pwd->pw_uid)
RETURNC(PAM_SUCCESS);
if (initgroups(pwd->pw_name, pwd->pw_gid) < 0 ||
setegid(pwd->pw_gid) < 0 || seteuid(pwd->pw_uid) < 0) {
openpam_restore_cred(pamh);
RETURNC(PAM_SYSTEM_ERR);
}
RETURNC(PAM_SUCCESS);
}
/*
* Error codes:
*
* =pam_set_data
* PAM_SYSTEM_ERR
* PAM_BUF_ERR
* PAM_PERM_DENIED
*/
/**
* The =openpam_borrow_cred function saves the current credentials and
* switches to those of the user specified by its =pwd argument.
* The affected credentials are the effective UID, the effective GID, and
* the group access list.
* The original credentials can be restored using =openpam_restore_cred.
*
* >setegid 2
* >seteuid 2
* >setgroups 2
*/
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