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.\"
.\" Copyright (c) 2011, 2013 Robert N. M. Watson
.\" Copyright (c) 2011 Jonathan Anderson
.\" 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.
.\"
.\" $FreeBSD$
.\"
.Dd February 25, 2016
.Dt CAPSICUM 4
.Os
.Sh NAME
.Nm Capsicum
.Nd lightweight OS capability and sandbox framework
.Sh SYNOPSIS
.Cd "options CAPABILITY_MODE"
.Cd "options CAPABILITIES"
.Sh DESCRIPTION
.Nm
is a lightweight OS capability and sandbox framework implementing a hybrid
capability system model.
.Nm
can be used for application and library compartmentalisation, the
decomposition of larger bodies of software into isolated (sandboxed)
components in order to implement security policies and limit the impact of
software vulnerabilities.
.Pp
.Nm
provides two core kernel primitives:
.Bl -tag -width indent
.It capability mode
A process mode, entered by invoking
.Xr cap_enter 2 ,
in which access to global OS namespaces (such as the file system and PID
namespaces) is restricted; only explicitly delegated rights, referenced by
memory mappings or file descriptors, may be used.
Once set, the flag is inherited by future children processes, and may not be
cleared.
.It capabilities
Limit operations that can be called on file descriptors.
For example, a file descriptor returned by
.Xr open 2
may be refined using
.Xr cap_rights_limit 2
so that only
.Xr read 2
and
.Xr write 2
can be called, but not
.Xr fchmod 2 .
The complete list of the capability rights can be found in the
.Xr rights 4
manual page.
.El
.Pp
In some cases,
.Nm
requires use of alternatives to traditional POSIX APIs in order to name
objects using capabilities rather than global namespaces:
.Bl -tag -width indent
.It process descriptors
File descriptors representing processes, allowing parent processes to manage
child processes without requiring access to the PID namespace; described in
greater detail in
.Xr procdesc 4 .
.It anonymous shared memory
An extension to the POSIX shared memory API to support anonymous swap objects
associated with file descriptors; described in greater detail in
.Xr shm_open 2 .
.El
.Sh SEE ALSO
.Xr cap_enter 2 ,
.Xr cap_fcntls_limit 2 ,
.Xr cap_getmode 2 ,
.Xr cap_ioctls_limit 2 ,
.Xr cap_rights_limit 2 ,
.Xr fchmod 2 ,
.Xr open 2 ,
.Xr pdfork 2 ,
.Xr pdgetpid 2 ,
.Xr pdkill 2 ,
.Xr pdwait4 2 ,
.Xr read 2 ,
.Xr shm_open 2 ,
.Xr write 2 ,
.Xr cap_rights_get 3 ,
.Xr casper 3 ,
.Xr procdesc 4 ,
.Sh HISTORY
.Nm
first appeared in
.Fx 9.0 ,
and was developed at the University of Cambridge.
.Sh AUTHORS
.Nm
was developed by
.An -nosplit
.An Robert Watson Aq Mt rwatson@FreeBSD.org
and
.An Jonathan Anderson Aq Mt jonathan@FreeBSD.org
at the University of Cambridge, and
.An Ben Laurie Aq Mt benl@FreeBSD.org
and
.An Kris Kennaway Aq Mt kris@FreeBSD.org
at Google, Inc., and
.An Pawel Jakub Dawidek Aq Mt pawel@dawidek.net .
|
