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Re: [saag] Call for Participation: IETF 73 MAC Labeling Bar BOF



Hello,
    Sorry for taking so long to respond to this but I was out sick the
better part of last week. The three documents are listed below and one
of them is attached to the email since it was an RFC posting to the
SELinux mailing list. That attachment is by Joy Latten of IBM and
pertains to labeled IPsec.

MAC Security Label Requirements for NFSv4
http://tools.ietf.org/id/draft-quigley-nfsv4-sec-label-requirements-01.txt

Common Architecture Label IPv6 Security Option (CALIPSO)
http://tools.ietf.org/id/draft-stjohns-sipso-05.txt

Two attached Documents by Joy Latten for Labeled IPSec

Dave

On Mon, 2008-10-06 at 14:47 +0800, Sean Shen wrote:
> hi, Dave,
> I am not clear about the prospective topics of the bar bof. Can you point me
> to the 3 draft you mentioned?
> Thanks
> 
> Sean
> 
> >-----Original Message-----
> >From: saag-bounces at ietf.org [mailto:saag-bounces at ietf.org] On 
> >Behalf Of David P. Quigley
> >Sent: Wednesday, October 01, 2008 6:06 AM
> >To: paul.moore at hp.com; latten at austin.ibm.com; 
> >Kurt.Zeilenga at Isode.com; saag at ietf.org; 
> >rja at extremenetworks.com; Nicolas.Williams at sun.com; Jarrett.Lu at sun.com
> >Subject: [saag] Call for Participation: IETF 73 MAC Labeling Bar BOF
> >
> >Hello, 
> >
> >I am organizing a Bar BOF to discuss the use of security 
> >labels in IETF protocols. Recently there have been at least 
> >three drafts introduced to the IETF which deal with security 
> >labels. While there may be other drafts in the work that deal 
> >with this topic, from the three I've seen there is at least 
> >one issue where myself and others believe we need to reach a 
> >consensus. 
> >
> >According to the IETF 73 cutoff dates list we won't know the 
> >final agenda for the event until October 27th. Once this date 
> >rolls around I will post a list of suggested dates and times 
> >for the BOF to take place. I also need to figure out where in 
> >the hotel to host the BOF. As the name suggests we can hold it 
> >in the hotel's bar, however another suggestion has been to get 
> >a room at a restaurant and hold the meeting over dinner. 
> >Depending on the interest in this BOF neither of these options 
> >may accommodate the number of people interested. In that case 
> >I'll have to see if I can find a more suitable place to hold the BOF.
> >Hopefully I will have this information to you before we arrive 
> >at IETF 73 but if I don't I'll make sure I inform everyone of 
> >where I will post the information.
> >
> >As of right now I have four people interested in the BOF and I 
> >hope to have more as time passes. I would like to be able to 
> >create a mailing list for the BOF but unfortunately I am not 
> >able to do that where I am. If someone else would like to host 
> >the mailing list (Not to be taken as a solicitation by the US
> >Govt) that would be great. For now if you are interested in 
> >the BOF feel free to email me so I have an idea of the general 
> >interest.
> >
> >The current agenda only has one item on it and that is the 
> >specification of a DOI. In the recent weeks I've read three 
> >drafts that have three different specifications of Domains of 
> >Interpretation (DOIs). While this is the only thing I have at 
> >the moment if you have other suggestions for topics or drafts 
> >you would like to discuss please bring them to my attention so 
> >I can make sure to add them to the agenda.
> >
> >Dave Quigley
> >
> >_______________________________________________
> >saag mailing list
> >saag at ietf.org
> >https://www.ietf.org/mailman/listinfo/saag
> >
> 
Network Working Group                                   J. Latten
Internet-Draft                                          G. Wilson
Intended Status: Standards Track                        S. Hallyn
Expires: ?                                                    IBM
                                                        T. Jaeger
                                                       Penn State
                                                        June 2008

                        Security Label Addendum to 
                    IPsec Domain of Interpretation (DOI)
                      for Internet Security Association 
                    and Key Management Protocol (ISAKMP)

                  draft-jml-ipsec-ikev1-security-label-00

Status of This Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
   aware will be disclosed, in accordance with Section 6 of BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups. Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time. It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress".

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on December, 2008.

Copyright Notice

   Copyright (C) The IETF Trust (2008)

Abstract

   This document describes the need for and the use of a security label
   within IPsec. It describes the extension to the Internet IP Security



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   Domain of Interpretation (IPsec DOI) [RFC2407] for the Internet
   Security Association and Key Management Protocol (ISAKMP) [RFC2408]. 
   This extension supports the negotiation of the security label for a 
   particular IP Authentication Header (AH) [RFC4302] or IP 
   Encapsulating Security Payload (ESP) [RFC4303] security association.

1. Introduction

   Traditionally, security context referred to the security level and
   category used by Multilevel Security (MLS). This document will refer
   to the security level and category as the security classification.

   Current security mechanisms, such as SELinux, use the security
   classification and additional security attributes to form their 
   security context. For example, a type for type enforcement. 
  
   Techniques such as IP Security Options (IPSO) allow IP datagrams to
   be labeled with an MLS security classification [RFC1108]. This 
   ensured the same security applied to local objects and resources was 
   utilized when communicating over the network with homogenous systems.
   However, these techniques cannot pass along the additional security
   attributes used in current security mechanisms.

   The ISAKMP specification defines a Situation field in the Security 
   Association payload [RFC2408]. The IPsec DOI describes the use of 
   this field to communicate sensitivity and integrity classification 
   information between initiator and responder when negotiating a 
   security association [RFC2407]. However, it does not provide for 
   additional security attributes that may be required by the security 
   mechanism being deployed in the environment.

   This document describes the additions to the IPsec DOI for ISAKMP
   that are needed to support communication of additional security 
   attributes between two hosts, in particular a security label.

2. Terminology
 
   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].











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3. IPsec Security Association Attribute

    The following SA attribute definition is used in Phase II of an
    Internet Key Exchange Protocol (IKE) negotiation that includes a 
    security label. The attribute type is Variable-Length (V).  
    Encoding of attributes is defined in the base ISAKMP specification 
    [RFC2408].

    Attribute Type

                class                   value           type
          ------------------------------------------------------
               Security Label             ?              V
    
    Class Values

      Security Label

        Specifies that the security association is being negotiated 
        in an environment that requires labeled security. This field 
        will contain the security label.

        The security label has the following format.

        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     doi       |  algorithm    |            length             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                 security label (variable)                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 1: Security Label format

       - doi (1 octet) - The first octet contains the security label's
         domain of interpretation.

         The domain of interpretation can be viewed as a group of
         systems that agree on the meaning of particular values within
         the security label of a security mechanism.

         The value of 1 is reserved as the default.

         Reserved       0
         Default        1

       - algorithm (1 octet) - The second octet contains the security 
         label's algorithm.




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         The security label's algorithm specifies the security
         mechanism or context in which the label is applicable. For
         example, the security label is interpreted within the SELinux
         context.

         Requests for assignment of additional algorithms should be 
         addressed to the Internet Assigned Numbers Authority (IANA).

         Reserved       0
         SELinux        1
         Smack          2
         Private Use    120-128

       - length (2 octets) - The third and fourth octets contain the 
         string length of the security context.

       - security label (1 or more octets) - The security label. The
         actual content will be dependent on the security algorithm
         that is specified. Within IKE context, this is regarded as
         an opaque bit string.

3. Attribute Negotiation

   If an implementation receives an IPsec DOI attribute or attribute
   value that it does not support, it SHOULD send an 
   ATTRIBUTES-NOT-SUPPORT and the security association negotiation 
   and setup MUST be aborted.

4. Security Considerations

   This document describes an extension to IKE [RFC2409] and ISAKMP 
   [RFC2408] protocols. The use of the described security label should 
   not change the basic security features of the two. 

   The IPsec DOI describes a Situation field whose values can be 
   SIT_SECRECY and/or SIT_INTEGRITY. When SIT_SECRECY is used, it 
   indicates an environment requiring labeled secrecy and is
   followed with sensitivity label. When SIT_INTEGITY is used,
   it indicates an environment requiring labeled integrity and 
   is followed with integrity information. 

   SIT_SECRECY and SIT_INTEGRITY themselves indicate the use of
   a security label and therefore the security attribute described
   in this document MUST NOT be used in conjunction with either.
   The new security attribute extends the existing security
   mechanism to allow for additional interpretations of a security
   label and not just those defined by SIT_SECRECY and SIT INTEGRITY.
   It is possible that the sensitivity level and/or integrity level are



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   included in the security label defined by the security algorithm 
   using the new security attribute.

5. IANA Considerations

   This document contains two new "magic numbers" which are allocated
   and maintained by IANA registry.

        - The class value for the security label attribute.

                  class            value     type
              -----------------------------------------
                Security Label       ?        V

          Only one value assigned by IANA is required.

          - The value for the security algorithm.

                SELinux         1(?)
                Smack           2(?)

          Additional values may be assigned by IANA for the
          security mechanisms requiring IKE to communicate its
          security label.

Acknowledgements

   The authors would like to thank Stephen Smalley, James Morris and
   the SELinux community for their work on labeled ipsec.

Normative References

   [RFC2119]    Bradner, S., "Key words for use in RFCs to Indicate
                Requirement Level", BCP 14, RFC 2119, March 1997.

   [RFC2407]    Piper, D., "The Internet IP Security Domain of
                Interpretation for ISAKMP", RFC 2407, November 1998.

   [RFC2408]    Maughan, D., Schertler, M., Schneider, M., and
                J. Turner, "Internet Security Association and Key
                Management Protocol", RFC 2408, November 1998.

   [RFC2409]    Harkins, D. and D. Carrel, "The Internet Key Exchange",
                RFC 2409, November 1998.

   [RFC4302]   Kent, S., "IP Authentication Header", RFC 4302, 
               December 2005.




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   [RFC4303]   Kent, S., "IP Encapsulating Security Payload (ESP)", 
               RFC 4303, December 2005. 

Informative references

   [RFC1108]   Kent, S., "U.S. DoD Security Options for the Internet
               Protocol, RFC 1108, November 1991.

Authors' Addresses

Joy Latten
IBM 
email: latten at austin.ibm.com

George Wilson
IBM 
email: gcwilson at us.ibm.com

Serge Hallyn
IBM
email: serue at us.ibm.com

Trent Jaeger
Penn State
email: tjaeger at cse.psu.edu


























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Full Copyright Statement

   Copyright (C) The IETF Trust (2008).

   This document is subject to the rights, licenses and restrictions 
   contained in BCP 78, and except as set forth therein, the authors
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Network Working Group                                   J. Latten
Internet-Draft                                          G. Wilson
Intended Status: Standards Track                        S. Hallyn
Expires: ?                                                    IBM
                                                        T. Jaeger
                                                       Penn State
                                                        July 2008

                    Security Label Addendum to IPsec
                 draft-jml-ipsec-ikev2-security-label-00


Status of This Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
   aware will be disclosed, in accordance with Section 6 of BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups. Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time. It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress".

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on December, 2008.

Copyright Notice

   Copyright (C) The IETF Trust (2008)

Abstract

   This document describes the high-level requirements needed within
   IPsec to support Mandatory Access Control (MAC) on network
   communications. It describes the extensions to the Security
   Architecture for the Internet Protocol [RFC4301] and the Internet
   Key Exchange Protocol Version 2 [RFC4306]. It also describes the 



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   negotiation of the security label for a particular Authentication 
   Header (AH) [RFC4302] and/or Encapsulating Security Payload (ESP) 
   [RFC4303] security association.

1. Introduction

   In computer security, Mandatory Access Control usually refers to a
   system in which all subjects and objects are labeled with a security
   context. The security context is comprised of a set of security
   attributes. The security contexts along with a system authorization 
   policy determine access. Rules within the system authorization policy 
   determine whether the access will be granted based on the security 
   attributes of the subject and object.

   Traditionally, MAC implied Multilevel Security (MLS) systems. MLS
   utilizes a security context consisting of a sensitivity or security
   level and category. This document will refer to the security level 
   and category as the security classiffication. In MLS, the use of a
   security classification allowed segregation of information thus
   facilitating data confidentiality. 

   MAC systems have become more mainstream and is no longer just
   associated with MLS. Within a strictly hierarchical system such as 
   MLS, often there are tasks that need to be exempt from the MLS
   policy, thus leaving them exposed. However, methods such as Type 
   Enforcement (TE) are not hierarchical and allow precise rules to 
   be written about access using security attributes [MayMacCap]. TE can
   be used to control access these "exempt" tasks. A MAC system can 
   employ both MLS and TE to control access. Such systems require 
   additional security attributes besides the security classification 
   used by MLS. For example, a domain type attribute may be used to 
   control access in TE [MayMacCap]. 

   These MAC systems concentrate on securing local objects and
   resources but have no way of applying their security contexts to
   network communications to ensure the same security when
   communicating with homogenous systems.

   Techniques such as IP Security Options (IPSO) allow IP datagrams to 
   be labeled with a MLS security classification [RFC1108]. However,
   they do not accomodate additional security attributes such as the 
   type in TE. MAC implementations requiring additional security 
   attributes, such as SELinux, can use IPsec mechanisms to control 
   access [LevIPsecMAC].

   This document will describe how IPsec mechanisms can support 
   MAC networking. It will also describe the additions to IKEv2 to 
   support communication of a security context during negotiations to 



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   establish an AH and ESP security association. 

   Within this document, security label and security context refer to
   the same thing. And MAC networking and labeled networking are
   used interchangeably. 

2. Terminology
 
   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

3. Labeled Networking

   Within a MAC environment, the underlying security mechanism applies 
   a security context to all the subjects and objects on the local
   system. The security context along with a MAC authorization policy 
   determines whether a subject may access an object.

   In labeled networking, a security context is applied to data 
   exported over the network. The MAC system can then use labeled 
   networking to make informed access decisions. Systems wishing to 
   communicate with each other must deploy the same MAC authorization 
   policy and security context for consistency.

   IPsec mechanisms can support labeled networking whether implicit or
   explicit labels are being used.

   Explicit labeling refers to transmitting the security context in the
   IP datagram, such as in IPSO. When explicit labeling is used the 
   encryption and authentication services provided in IPsec can be
   used to authenticate the bindings between the security label in the
   IP header and payload and provide confidentiality [RFC2401].

   In an implicit labeling scheme, the security context is not
   transmitted as part of the IP datagram. IPsec provides implicit
   labeling in that the security context is part of the IPsec Security 
   Association and not transmitted with each packet.

3.1 Relationship Between a Security Association and Security Label

   In MAC networking, the traffic between two systems may require 
   several different security contexts. For example, ftp and a mail 
   program may each label their data with a different security context. 
   Recall that SAs exist in pairs, one for inbound and one for outbound. 
   Each instance of a security label will require an SA pair. Thus 
   traffic between two systems may have several SA pairs with identical 
   selectors except for the security context. If using a combination of 



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   ESP and AH, then there will be an ESP SA pair and an AH SA pair per 
   instance of a security label.

3.2 Security Context Selector

   [RFC4301] describes the Security Policy Database (SPD), and the
   Security Association Database (SAD) and corresponding selectors.

   MAC networking introduces an additional selector, the Security
   Context selector. This selector is only required when MAC
   networking is deployed. 
    
        - Security Context: MAC implementation's security context.
          The security context can be an IPSO/CIPSO label when
          IPsec is used to support explicit labels.

   Recall, in MAC networking, multiple SAs may exist between two 
   systems differing only in their security labels. The Security Context
   selector ensures that the appropriate SA pair is used to secure a
   particular communication.

   The Security Context selector within the SPD allows the system
   administrator to specify which traffic streams will be authorized
   to communicate within the system's MAC policy. It also specifies
   which traffic streams will have labeled communications and which
   will not.

3.3 Security Context Selector and PFP

   [RFC4301] introduced and described Populate From Packet (PFP)
   flags. When creating an SA, the PFP flag determines whether to
   instantiate the corresponding selector in the new SA with 
   information from the packet that triggered the creation or from
   information in the corresponding SPD entry.

   In MAC implementations, the security context that will be associated
   with the new SA MUST NOT be the SPD entry's security context. The
   security contexts in the SPD entry and in the SA entry are to label
   two different objects respectively. The security context in the SPD 
   entry controls access to the entry itself and it's IPsec 
   configuration information. Thus the SPD entry itself is considered an 
   object. The SA's security context provides security attributes for 
   the packet which can also indicate the security attributes of the 
   sender or process. Keeping these separate allows a MAC implementation 
   to control which packets may use a particular IPsec configuration.

   Therefore, when using IPsec to provide implicit labels, the PFP flag 
   must not be used to determine where to get the security context for 
   the new SA.


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3.4 Outbound Processing for MAC Networking

   When consulting the SPD for an outbound policy, the data's security
   label is used to determine if it is authorized to access the
   particular SPD entry and use its configuration information for
   sending. This adds the additional check in that the outbound packet
   will not generate an SA pair that the policy entry does not allow.
   So for example, in an MLS implementation, a high secrecy process
   cannot generate an SA allowing it to send data to a low secrecy 
   process.

   Similarly, when consulting the SAD to find an outbound SA, the
   the data's security context is used to select the appropriate SA to
   send on.

   In the case that a suitable outbound policy is found, but there isn't
   an SA, the message sent to the key management system to create an SA
   MUST contain the security label associated with the data. This allows 
   for the key manager to create an SA pair with the correct security 
   label for the data to be transmitted.

   A MAC implementation MAY label it's interface and/or configured IP
   address. If so, before forwarding the packet out to its destination,
   a check should be made that the outbound packet is authorized to
   send out on the interface and/or configured ip address [RFC2401].

3.4 Inbound Processing for MAC Networking

   The use of the SPI to map IPsec protected packets to an SA ensures
   we select the correct SA to process the inbound packet.

   The MAC implementation MUST retain the binding between the data
   received in the IPsec protected packet and the security label in
   the SA used to process the packet. This is required so that
   suitable MAC policy decisions can be made when delivering the data
   to an application or when fowarding. The means for maintaining this
   binding are implementation specific. [RFC2401]

   A MAC implementation MAY label it's interface or configured IP
   address. If so, the MAC implementation SHOULD check the inbound
   packet's security label (as defined by the SA used to process the
   packet) with the security label of the interface or configured IP
   address before forwarding to upper-layer protocol or to
   destination [RFC2401].

3.5 MAC Processing for Security Gateways

   A security gateway enforcing MAC and using labeled SAs MUST follow



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   the inbound and outbound processing mentioned above as well as some
   additional processing particular to the intermediate protection of
   packets in a MAC environment [RFC2401].

   A security gateway enforcing MAC MUST create and use appropriate
   SAs to protect packets that it forwards for systems behind it. 
   [RFC2401] The systems behind the security gateway may or may not be 
   using MAC. The gateway SHOULD utilize various attributes of the 
   traffic and/or existing labels to determine the security labels for 
   the SAs to be created and applied.

   Similarly, such a gateway SHOULD accept and process inbound AH
   and/or ESP packets and forward appropriately, utilizing various
   attributes of the traffic and/or existing labels [RFC2401].

4. Security Context Transform

   When the initiator requests a new SA to be created, the 
   security context is communicated in the information required for 
   the new IPsec SA. Security contexts are not communicated for IKE_SAs, 
   only IPsec SAs.

   The following transform definition is used to communicate a security
   context when creating the CHILD_SA in the IKE_AUTH exchange or when
   creating or rekeying an IPsec SA in the CREATE_CHILD_SA exchange.

   The transform type value is:

   Description        Transform Type      Used In
   .................................................
   Security Context       (?)6            ESP and AH

   When using IPsec's implicit labelin, the existence of a security
   context for the SPD entry indicates all SAs created by this entry
   MUST be labeled. If an SPD entry does not have a security context, 
   then resulting SAs will not have a security context. Within MAC 
   it may be desireable that some network communications not be labeled 
   and just protected by IPsec. For example, a security gateway 
   enforcing MAC but the systems behind it do not. These SPD entries 
   would not have a security context. However, when the security 
   gateway talks to another security gateway, it may want to use 
   implicit labeling. Therefore, the use of a security context with 
   the ESP and AH protocols when MAC is enforced is optional.

   Only one transform of type (?)6 is allowed per protocol. In other
   words, you cannot communicate two different security contexts within 
   a single SA payload being negotiated.




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   For Transform Type (?)6 (Security Context), the defined Transform IDs
   are:
  
   Security Mechanism          Number
   ...........................................
   Reserved                     0
   SELinux                      (?)1  
   Smack                        (?)2
   Reserved to IANA             (?)3 - 1023
   Private Use                  1024 - 65535


   The Transform Attribute Type:

   Attribute Type       Value       Attribute Format
   .......................................................
   Security Context     (?)18             TLV

   The attribute format is Type/Length/Value allowing for a variable
   length security context.


   The security context has the following format.

    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     doi       |   security context (variable length)          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  Figure 1: Security Context Format

       - doi (1 octet) - The first octet contains the security label's
         domain of interpretation.

         The domain of interpretation can be viewed as a group of
         systems that agree on the meaning of particular values within
         the security label of a security mechanism.

       Reserved        0
       Default        (?)1
       Private Use    (?)2 - 255

       - security context (variable length number of octets)
         The actual content will be dependent on the security mechanism
         that is specified. Within IKE context, this is regarded as
         an opaque bit string.





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4.1 Attribute Negotiation

   The description of attribute negotiation in [RFC4306] is applicable
   also when using security contexts. In addition, only one security
   context transform (Type 6) is allowed per protocol. And if the
   initiator sends multiple proposals when negotiating an SA, each
   proposal MUST contain the same transform type and security context.
   In other words, a single SA negotiation should contain only one
   security context.

4.3 CREATE_CHILD_SA Exchange

   [RFC4306] describes the NO_ADDITIONAL_SAS notification.
   This notification is sent by a responder who is unwilling to accept
   additional SAs on an IKE_SA or a minimal IPsec implementation.

   Within MAC, the data transmitted between two systems may have 
   different security contexts. For example, ftp and telnet data may
   each have their own security contexts. Each instance of a security
   context requires an SA pair to support context granularity.  
   There may be multiple SAs with same selectors except for the 
   security context selector. A responder should be willing to accept 
   more than one SA on an IKE_SA in MAC networking.

4. Security Considerations

   Some IPsec implementations may dynamically update the SPD.
   If the responder does not have an SPD entry, the information within
   the SA payload is used to generate an SPD entry.

   MAC networking may impose limitations on IPsec implementations that
   dynamically update the SPD. The security contexts associated with an
   SPD entry and an SA are for different purposes as described
   already in this document. Therefore, the security context in the
   SA should not be used as the security context for the SPD entry.

   IPsec implementations that generate SPD entries during SA
   negotiation and wish to enforce labeled networking will require a
   mechanism for system administrators to specify the security context
   to be used for these SPD entries.











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5. IANA Considerations

   This document contains several new numbers which are allocated
   and maintained by the IANA registry.

   - The Transform Type value for the security context.

     Description             Transform type
    -----------------------------------------
     Security Context             (?)6

   - The Transform IDs defined within the Security Context Transform
     Type.

     Name              Number
    ---------------------------
     Reserved              0
     SELinux            (?)1
     Smack              (?)2
     Reserved to IANA   (?)3 - 1023
     Private Use        1024 - 65535

     Additional values may be assigned by IANA for the security
     mechanisms requiring IKE to communicate its security label.

   - The Security Context attribute type.

     Attribute Type      Value      Attribute Format
    -----------------------------------------------------
     Security Context     (?)18           TLV

6. Acknowledgements

   The authors would like to thank Stephen Smalley and James Morris
   for their contributions during the initial design; and the members 
   of the SELinux community who have contributed to the development 
   and improvement of labeled ipsec and this specification.

7. References

7.1 Normative References

   [RFC2119]    Bradner, S., "Key words for use in RFCs to Indicate
                Requirement Level", BCP 14, RFC 2119, March 1997.

   [RFC4301]    Kent, S. and K. Seo, "Security Architecture for the
                Internet Protocol", RFC 4301, December 2005.



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   [RFC4306]    Kaufman, Ed., "Internet Key Exchange (IKEv2) Protocol",
                RFC 4306, December 2005.

7.2 Informative References

   [LevIPsecMAC]
                Jaeger, T., King, David., Butler, K., Hallyn, S.,
                Latten, J., Zhang, X., "Leveraging IPsec for Mandatory
                Per-Packet Access Control", 2006
                http://www.cse.psu.edu/~tjaeger/papers/securecomm06.pdf

   [MayMacCap]  Mayer, F., Macmillan K., Caplan D., SELinux by Example, 
                Section 1.2.4, Prentice Hall, Upper Saddle River, NJ, 
                2007

   [RFC1108]    Kent, S., "U.S. DoD Security Options for the Internet
                Protocol", RFC 1108, November 1991. 

   [RFC2401]    Kent, S., Atkinson, R., Security Architecture for the
                Internet Protocol, RFC 2401, November 1998. 

   [RFC4302]    Kent, S., "IP Authentication Header", RFC 4302,
                December 2005.

   [RFC4303]    Kent, S. "IP Encapsulating Security Payload (ESP)",
                RFC 4303, December 2005.


Authors' Addresses

Joy Latten
IBM
email: latten at austin.ibm.com

George Wilson
IBM
email: gcwilson at us.ibm.com

Serge Hallyn
IBM
email: serue at us.ibm.com

Trent Jaeger
Penn State
email: tjaeger at cse.psu.edu






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