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290 lines
10 KiB
C
290 lines
10 KiB
C
/*-
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* Copyright (c) 2001 Networks Associates Technology, Inc.
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* All rights reserved.
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*
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* This software was developed for the FreeBSD Project by NAI Labs, the
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* Security Research Division of Network Associates, Inc. under
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* DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA
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* CHATS research program.
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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 author may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT 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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* $Id$
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* $FreeBSD$
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*/
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/*
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* This file contains functions that make access control decisions
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* concerning wether or not given system calls should be allowed
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* or denied. This activity is called "mediation". These functions
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* generally consider both the parameters passed to a system call
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* and the current internal state of LOMAC in the course of making
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* a decision. However, they do not modify these parameters or
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* LOMAC's internal state. Functions for modifying LOMAC's internal
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* state can be found in lomac_monitor.c.
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*
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*/
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#include "kernel_interface.h"
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#include "kernel_mediate.h"
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#if 0
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#include "lomac_plm.h"
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#endif
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#include "kernel_log.h"
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/* mediate_subject_level_subject()
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*
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* in: op_s - name of operation to mediate
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* p_subject_one - subject one (for informational purposes only)
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* level_one - already-known level of the first subject
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* p_subject_two - subject two
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* out: nothing
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* return: value condition
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* ----- ---------
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* 0 caller should deny operation
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* 1 caller should allow operation
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*
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* This function returns 1 if `p_subject_one's level is at least
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* as great as `p_subject_two's level. Otherwise, it logs a permission
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* failure on operation `op_s' and returns 0.
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*
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* This function is used to mediate pgrp changes.
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*
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*/
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int
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mediate_subject_level_subject(const char *op_s,
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const lomac_subject_t *p_subject_one, level_t level_one,
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lomac_subject_t *p_subject_two) {
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lattr_t lattr_two; /* lattr of `p_subject_two' */
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int ret_val; /* result to return to caller */
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#ifdef NO_MEDIATION
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ret_val = 1; /* no denials, just logging */
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#else
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ret_val = 0; /* pessimistically assume deny */
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#endif
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get_subject_lattr(p_subject_two, &lattr_two);
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if (lattr_two.level <= level_one) {
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ret_val = 1; /* OK, allow */
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} else if (lomac_verbose_demote_deny) {
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lomac_log_t *logmsg = log_start();
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log_append_string(logmsg, "LOMAC: denied level-");
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log_append_int(logmsg, level_one);
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log_append_string(logmsg, " proc ");
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log_append_subject_id(logmsg, p_subject_one);
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log_append_string(logmsg, " ");
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log_append_string(logmsg, op_s);
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log_append_string(logmsg, " to level-");
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log_append_int(logmsg, lattr_two.level);
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log_append_string(logmsg, " proc ");
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log_append_subject_id(logmsg, p_subject_two);
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log_print(logmsg);
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}
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return (ret_val);
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} /* mediate_subject_subject() */
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/* mediate_subject_object()
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*
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* in: op_s - string describing operation, like "write" or "writev"
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* p_subject - subject trying to operate on `p_object'.
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* p_object - object that `p_subject' is trying to operate on.
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* out: nothing
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* return: value condition
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* ----- ---------
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* 0 Caller should prevent operation
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* 1 Caller should permit operation
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*
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* This function returns 1 if the level of `p_object' is less than or
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* equal to the level of `p_subject'. Otherwise, it returns 0 and
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* logs a permission denial on `op_s'.
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*
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* This function allows LOMAC to mediate write and writev system calls.
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*
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*/
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int
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mediate_subject_object(const char *op_s, lomac_subject_t *p_subject,
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const lomac_object_t *p_object) {
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lattr_t subject_lattr; /* lattr of `p_subject' */
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lattr_t object_lattr; /* lattr of `p_object' */
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int ret_val; /* value to return to caller */
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#ifdef NO_MEDIATION
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ret_val = 1; /* allow operation regardless of decision */
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#else
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ret_val = 0; /* pessimistically assume deny */
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#endif
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/* Get the lattrs of `p_subject' and `p_object' so we can compare them. */
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get_subject_lattr(p_subject, &subject_lattr);
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get_object_lattr(p_object, &object_lattr);
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/*
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* If `p_subject's level is less than `p_object's level,
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* we indicate that the operation must not be allowed.
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*/
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if (!lomac_must_deny(&subject_lattr, &object_lattr) ||
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object_lattr.flags & LOMAC_ATTR_LOWWRITE) {
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ret_val = 1; /* allow operation */
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} else if (lomac_verbose_demote_deny) {
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lomac_log_t *logmsg = log_start();
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log_append_string(logmsg, "LOMAC: level-");
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log_append_int(logmsg, subject_lattr.level);
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log_append_string(logmsg, " proc ");
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log_append_subject_id(logmsg, p_subject);
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log_append_string(logmsg, " denied ");
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log_append_string(logmsg, op_s);
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log_append_string(logmsg, " to level-");
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log_append_int(logmsg, object_lattr.level);
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log_append_string(logmsg, " object ");
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log_append_object_id(logmsg, p_object);
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log_append_string(logmsg, "\n");
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log_print(logmsg);
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}
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return (ret_val);
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} /* mediate_subject_object() */
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/* mediate_subject_object_open()
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*
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* in: p_subject - subject trying to operate on `p_object'.
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* p_object - object that `p_subject' is trying to operate on.
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* out: nothing
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* return: value condition
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* ----- ---------
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* 0 Caller should prevent operation
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* 1 Caller should permit operation
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*
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* This function returns 1 if the level of `p_object' is less than or
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* equal to the level of `p_subject'. Otherwise, it returns 0 and
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* logs a permission denial on `op_s'.
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*
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* This function allows LOMAC to mediate open system calls.
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*
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*/
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int
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mediate_subject_object_open(lomac_subject_t *p_subject,
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const lomac_object_t *p_object) {
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lattr_t subject_lattr; /* lattr of `p_subject' */
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lattr_t object_lattr; /* lattr of `p_object' */
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int ret_val; /* value to return to caller */
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#ifdef NO_MEDIATION
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ret_val = 1; /* allow operation regardless of decision */
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#else
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ret_val = 0; /* pessimistically assume deny */
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#endif
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/* Get the lattrs of `p_subject' and `p_object' so we can compare them. */
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get_subject_lattr(p_subject, &subject_lattr);
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get_object_lattr(p_object, &object_lattr);
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/*
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* If `p_subject's level is less than `p_object's level,
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* we must indicate that the operation should not be allowed.
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*/
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if (lomac_must_deny(&subject_lattr, &object_lattr) &&
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object_lattr.flags & LOMAC_ATTR_LOWNOOPEN) {
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if (lomac_verbose_demote_deny) {
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lomac_log_t *logmsg = log_start();
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log_append_string(logmsg, "LOMAC: level-");
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log_append_int(logmsg, subject_lattr.level);
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log_append_string(logmsg, " proc ");
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log_append_subject_id(logmsg, p_subject);
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log_append_string(logmsg, " denied open to level-");
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log_append_int(logmsg, object_lattr.level);
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log_append_string(logmsg, " object ");
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log_append_object_id(logmsg, p_object);
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log_append_string(logmsg, "\n");
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log_print(logmsg);
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}
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} else {
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ret_val = 1; /* allow operation */
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} /* if/else allow/deny */
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return (ret_val);
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} /* mediate_subject_object() */
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/* mediate_subject_at_level()
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*
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* in: op_s - name of operation being mediated
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* p_subject - subject whose level we want to check
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* target_level - level to compare to `p_subject's level
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*
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* out: nothing
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* return: value condition
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* ----- ---------
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* 0 `p_subject' is not at `target_level'
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* 1 `p_subject' is at `target_level'
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*
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* This function provides a predicate for determining whether or not
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* `p_subject' is at the level specified by `target_level'. This
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* function compares `p_subject's level to `target_level'. If the
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* levels match, it retruns 1. Otherwise, it logs a permission denial
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* on `op_s' and returns 0.
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*
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*/
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int
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mediate_subject_at_level(const char *op_s, lomac_subject_t *p_subject,
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const level_t target_level) {
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lattr_t subject_lattr; /* lattr of `p_subject' */
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int ret_val; /* value returned to caller */
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#ifdef NO_MEDIATION
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ret_val = 1; /* allow operation regardless of decision */
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#else
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ret_val = 0; /* pessimistically assume deny */
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#endif
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/* Make `subject_lattr' the lattr of `p_subject'. */
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get_subject_lattr(p_subject, &subject_lattr);
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/* compare with `target_lattr */
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if (subject_lattr.level == target_level) {
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ret_val = 1; /* allow operation */
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} else if (lomac_verbose_demote_deny) {
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lomac_log_t *logmsg = log_start();
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log_append_string(logmsg, "LOMAC: denied level-");
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log_append_int(logmsg, subject_lattr.level);
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log_append_string(logmsg, " proc ");
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log_append_subject_id(logmsg, p_subject);
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log_append_string(logmsg, "'s ");
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log_append_string(logmsg, op_s);
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log_append_string(logmsg, ".\n");
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log_print(logmsg);
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}
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return (ret_val);
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} /* mediate_subject_at_level() */
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