/*- * Copyright (c) 2001 Networks Associates Technology, Inc. * All rights reserved. * * 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. * * 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: kernel_mediate.c,v 1.9 2001/10/17 15:19:40 bfeldman Exp $ */ /* * 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() */