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/*-
* Copyright (c) 2001 Networks Associates Technologies, Inc.
* All rights reserved.
*
* This software was developed for the FreeBSD Project by NAI Labs, 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.
*
* $Id$
* $FreeBSD$
*/
/*
* This file contains functions that make access control decisions
* concerning wether or not given system calls should be allowed
* or denied. This activity is called "mediation". These functions
* generally consider both the parameters passed to a system call
* and the current internal state of LOMAC in the course of making
* a decision. However, they do not modify these parameters or
* LOMAC's internal state. Functions for modifying LOMAC's internal
* state can be found in lomac_monitor.c.
*
*/
#include "kernel_interface.h"
#include "kernel_mediate.h"
#if 0
#include "lomac_plm.h"
#endif
#include "kernel_log.h"
/* mediate_subject_level_subject()
*
* in: op_s - name of operation to mediate
* p_subject_one - subject one (for informational purposes only)
* level_one - already-known level of the first subject
* p_subject_two - subject two
* out: nothing
* return: value condition
* ----- ---------
* 0 caller should deny operation
* 1 caller should allow operation
*
* This function returns 1 if `p_subject_one's level is at least
* as great as `p_subject_two's level. Otherwise, it logs a permission
* failure on operation `op_s' and returns 0.
*
* This function is used to mediate pgrp changes.
*
*/
int
mediate_subject_level_subject(const char *op_s,
const lomac_subject_t *p_subject_one, level_t level_one,
lomac_subject_t *p_subject_two) {
lattr_t lattr_two; /* lattr of `p_subject_two' */
int ret_val; /* result to return to caller */
#ifdef NO_MEDIATION
ret_val = 1; /* no denials, just logging */
#else
ret_val = 0; /* pessimistically assume deny */
#endif
get_subject_lattr(p_subject_two, &lattr_two);
if (lattr_two.level <= level_one) {
ret_val = 1; /* OK, allow */
} else if (lomac_verbose_demote_deny) {
lomac_log_t *logmsg = log_start();
log_append_string(logmsg, "LOMAC: denied level-");
log_append_int(logmsg, level_one);
log_append_string(logmsg, " proc ");
log_append_subject_id(logmsg, p_subject_one);
log_append_string(logmsg, " ");
log_append_string(logmsg, op_s);
log_append_string(logmsg, " to level-");
log_append_int(logmsg, lattr_two.level);
log_append_string(logmsg, " proc ");
log_append_subject_id(logmsg, p_subject_two);
log_print(logmsg);
}
return (ret_val);
} /* mediate_subject_subject() */
/* mediate_subject_object()
*
* in: op_s - string describing operation, like "write" or "writev"
* p_subject - subject trying to operate on `p_object'.
* p_object - object that `p_subject' is trying to operate on.
* out: nothing
* return: value condition
* ----- ---------
* 0 Caller should prevent operation
* 1 Caller should permit operation
*
* This function returns 1 if the level of `p_object' is less than or
* equal to the level of `p_subject'. Otherwise, it returns 0 and
* logs a permission denial on `op_s'.
*
* This function allows LOMAC to mediate write and writev system calls.
*
*/
int
mediate_subject_object(const char *op_s, lomac_subject_t *p_subject,
const lomac_object_t *p_object) {
lattr_t subject_lattr; /* lattr of `p_subject' */
lattr_t object_lattr; /* lattr of `p_object' */
int ret_val; /* value to return to caller */
#ifdef NO_MEDIATION
ret_val = 1; /* allow operation regardless of decision */
#else
ret_val = 0; /* pessimistically assume deny */
#endif
/* Get the lattrs of `p_subject' and `p_object' so we can compare them. */
get_subject_lattr(p_subject, &subject_lattr);
get_object_lattr(p_object, &object_lattr);
/*
* If `p_subject's level is less than `p_object's level,
* we indicate that the operation must not be allowed.
*/
if (!lomac_must_deny(&subject_lattr, &object_lattr) ||
object_lattr.flags & LOMAC_ATTR_LOWWRITE) {
ret_val = 1; /* allow operation */
} else if (lomac_verbose_demote_deny) {
lomac_log_t *logmsg = log_start();
log_append_string(logmsg, "LOMAC: level-");
log_append_int(logmsg, subject_lattr.level);
log_append_string(logmsg, " proc ");
log_append_subject_id(logmsg, p_subject);
log_append_string(logmsg, " denied ");
log_append_string(logmsg, op_s);
log_append_string(logmsg, " to level-");
log_append_int(logmsg, object_lattr.level);
log_append_string(logmsg, " object ");
log_append_object_id(logmsg, p_object);
log_append_string(logmsg, "\n");
log_print(logmsg);
}
return (ret_val);
} /* mediate_subject_object() */
/* mediate_subject_object_open()
*
* in: p_subject - subject trying to operate on `p_object'.
* p_object - object that `p_subject' is trying to operate on.
* out: nothing
* return: value condition
* ----- ---------
* 0 Caller should prevent operation
* 1 Caller should permit operation
*
* This function returns 1 if the level of `p_object' is less than or
* equal to the level of `p_subject'. Otherwise, it returns 0 and
* logs a permission denial on `op_s'.
*
* This function allows LOMAC to mediate open system calls.
*
*/
int
mediate_subject_object_open(lomac_subject_t *p_subject,
const lomac_object_t *p_object) {
lattr_t subject_lattr; /* lattr of `p_subject' */
lattr_t object_lattr; /* lattr of `p_object' */
int ret_val; /* value to return to caller */
#ifdef NO_MEDIATION
ret_val = 1; /* allow operation regardless of decision */
#else
ret_val = 0; /* pessimistically assume deny */
#endif
/* Get the lattrs of `p_subject' and `p_object' so we can compare them. */
get_subject_lattr(p_subject, &subject_lattr);
get_object_lattr(p_object, &object_lattr);
/*
* If `p_subject's level is less than `p_object's level,
* we must indicate that the operation should not be allowed.
*/
if (lomac_must_deny(&subject_lattr, &object_lattr) &&
object_lattr.flags & LOMAC_ATTR_LOWNOOPEN) {
if (lomac_verbose_demote_deny) {
lomac_log_t *logmsg = log_start();
log_append_string(logmsg, "LOMAC: level-");
log_append_int(logmsg, subject_lattr.level);
log_append_string(logmsg, " proc ");
log_append_subject_id(logmsg, p_subject);
log_append_string(logmsg, " denied open to level-");
log_append_int(logmsg, object_lattr.level);
log_append_string(logmsg, " object ");
log_append_object_id(logmsg, p_object);
log_append_string(logmsg, "\n");
log_print(logmsg);
}
} else {
ret_val = 1; /* allow operation */
} /* if/else allow/deny */
return (ret_val);
} /* mediate_subject_object() */
/* mediate_subject_at_level()
*
* in: op_s - name of operation being mediated
* p_subject - subject whose level we want to check
* target_level - level to compare to `p_subject's level
*
* out: nothing
* return: value condition
* ----- ---------
* 0 `p_subject' is not at `target_level'
* 1 `p_subject' is at `target_level'
*
* This function provides a predicate for determining whether or not
* `p_subject' is at the level specified by `target_level'. This
* function compares `p_subject's level to `target_level'. If the
* levels match, it retruns 1. Otherwise, it logs a permission denial
* on `op_s' and returns 0.
*
*/
int
mediate_subject_at_level(const char *op_s, lomac_subject_t *p_subject,
const level_t target_level) {
lattr_t subject_lattr; /* lattr of `p_subject' */
int ret_val; /* value returned to caller */
#ifdef NO_MEDIATION
ret_val = 1; /* allow operation regardless of decision */
#else
ret_val = 0; /* pessimistically assume deny */
#endif
/* Make `subject_lattr' the lattr of `p_subject'. */
get_subject_lattr(p_subject, &subject_lattr);
/* compare with `target_lattr */
if (subject_lattr.level == target_level) {
ret_val = 1; /* allow operation */
} else if (lomac_verbose_demote_deny) {
lomac_log_t *logmsg = log_start();
log_append_string(logmsg, "LOMAC: denied level-");
log_append_int(logmsg, subject_lattr.level);
log_append_string(logmsg, " proc ");
log_append_subject_id(logmsg, p_subject);
log_append_string(logmsg, "'s ");
log_append_string(logmsg, op_s);
log_append_string(logmsg, ".\n");
log_print(logmsg);
}
return (ret_val);
} /* mediate_subject_at_level() */
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