926571dfa7
allows registration of callbacks that can be used later for
cross-secmodel "safe" communication.
When a secmodel wishes to know a property maintained by another
secmodel, it has to submit a request to it so the other secmodel can
proceed to evaluating the request. This is done through the
secmodel_eval(9) call; example:
bool isroot;
error = secmodel_eval("org.netbsd.secmodel.suser", "is-root",
cred, &isroot);
if (error == 0 && !isroot)
result = KAUTH_RESULT_DENY;
This one asks the suser module if the credentials are assumed to be root
when evaluated by suser module. If the module is present, it will
respond. If absent, the call will return an error.
Args and command are arbitrarily defined; it's up to the secmodel(9) to
document what it expects.
Typical example is securelevel testing: when someone wants to know
whether securelevel is raised above a certain level or not, the caller
has to request this property to the secmodel_securelevel(9) module.
Given that securelevel module may be absent from system's context (thus
making access to the global "securelevel" variable impossible or
unsafe), this API can cope with this absence and return an error.
We are using secmodel_eval(9) to implement a secmodel_extensions(9)
module, which plugs with the bsd44, suser and securelevel secmodels
to provide the logic behind curtain, usermount and user_set_cpu_affinity
modes, without adding hooks to traditional secmodels. This solves a
real issue with the current secmodel(9) code, as usermount or
user_set_cpu_affinity are not really tied to secmodel_suser(9).
The secmodel_eval(9) is also used to restrict security.models settings
when securelevel is above 0, through the "is-securelevel-above"
evaluation:
- curtain can be enabled any time, but cannot be disabled if
securelevel is above 0.
- usermount/user_set_cpu_affinity can be disabled any time, but cannot
be enabled if securelevel is above 0.
Regarding sysctl(7) entries:
curtain and usermount are now found under security.models.extensions
tree. The security.curtain and vfs.generic.usermount are still
accessible for backwards compat.
Documentation is incoming, I am proof-reading my writings.
Written by elad@, reviewed and tested (anita test + interact for rights
tests) by me. ok elad@.
See also
http://mail-index.netbsd.org/tech-security/2011/11/29/msg000422.html
XXX might consider va0 mapping too.
XXX Having a secmodel(9) specific printf (like aprint_*) for reporting
secmodel(9) errors might be a good idea, but I am not sure on how
to design such a function right now.
64 lines
2.5 KiB
C
64 lines
2.5 KiB
C
/* $NetBSD: secmodel.h,v 1.4 2011/12/04 19:24:59 jym Exp $ */
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/*-
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* Copyright (c) 2006, 2011 Elad Efrat <elad@NetBSD.org>
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* All rights reserved.
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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 products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _SECMODEL_SECMODEL_H_
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#define _SECMODEL_SECMODEL_H_
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#include <prop/proplib.h>
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void secmodel_init(void);
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/*
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* Functions used for inter-secmodel communication, allowing evaluation
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* or setting information.
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*/
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typedef int (*secmodel_eval_t)(const char *, void *, void *);
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typedef int (*secmodel_setinfo_t)(void *); /* XXX TODO */
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/*
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* Secmodel entry.
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*/
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struct secmodel_descr {
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LIST_ENTRY(secmodel_descr) sm_list;
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const char *sm_id;
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const char *sm_name;
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prop_dictionary_t sm_behavior;
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secmodel_eval_t sm_eval;
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secmodel_setinfo_t sm_setinfo;
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};
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typedef struct secmodel_descr *secmodel_t;
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int secmodel_register(secmodel_t *, const char *, const char *,
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prop_dictionary_t, secmodel_eval_t, secmodel_setinfo_t);
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int secmodel_deregister(secmodel_t);
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int secmodel_nsecmodels(void);
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int secmodel_eval(const char *, const char *, void *, void *);
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int secmodel_setinfo(const char *, void *, int *); /* XXX TODO */
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#endif /* !_SECMODEL_SECMODEL_H_ */
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