593733ab80
Convert netlabel documentation to ReST. This was trivial: just add proper title markups. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Paul Moore <paul@paul-moore.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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57 lines
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===================================
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NetLabel CIPSO/IPv4 Protocol Engine
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===================================
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Paul Moore, paul.moore@hp.com
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May 17, 2006
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Overview
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========
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The NetLabel CIPSO/IPv4 protocol engine is based on the IETF Commercial
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IP Security Option (CIPSO) draft from July 16, 1992. A copy of this
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draft can be found in this directory
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(draft-ietf-cipso-ipsecurity-01.txt). While the IETF draft never made
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it to an RFC standard it has become a de-facto standard for labeled
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networking and is used in many trusted operating systems.
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Outbound Packet Processing
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==========================
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The CIPSO/IPv4 protocol engine applies the CIPSO IP option to packets by
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adding the CIPSO label to the socket. This causes all packets leaving the
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system through the socket to have the CIPSO IP option applied. The socket's
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CIPSO label can be changed at any point in time, however, it is recommended
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that it is set upon the socket's creation. The LSM can set the socket's CIPSO
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label by using the NetLabel security module API; if the NetLabel "domain" is
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configured to use CIPSO for packet labeling then a CIPSO IP option will be
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generated and attached to the socket.
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Inbound Packet Processing
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=========================
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The CIPSO/IPv4 protocol engine validates every CIPSO IP option it finds at the
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IP layer without any special handling required by the LSM. However, in order
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to decode and translate the CIPSO label on the packet the LSM must use the
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NetLabel security module API to extract the security attributes of the packet.
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This is typically done at the socket layer using the 'socket_sock_rcv_skb()'
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LSM hook.
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Label Translation
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=================
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The CIPSO/IPv4 protocol engine contains a mechanism to translate CIPSO security
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attributes such as sensitivity level and category to values which are
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appropriate for the host. These mappings are defined as part of a CIPSO
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Domain Of Interpretation (DOI) definition and are configured through the
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NetLabel user space communication layer. Each DOI definition can have a
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different security attribute mapping table.
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Label Translation Cache
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=======================
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The NetLabel system provides a framework for caching security attribute
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mappings from the network labels to the corresponding LSM identifiers. The
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CIPSO/IPv4 protocol engine supports this caching mechanism.
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