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Network Working Group                                        C. Qin, Ed.
Internet-Draft                                                     Y. Xi
Intended status: Standards Track                                   W. Xu
Expires: August 24, 2019                                     Alibaba-Inc
                                                       February 20, 2019


           IPv6 Router Advertisement Option for Network Boot
                      draft-qin-6man-nb-option-03

Abstract

   This document specifies an IPv6 Router Advertisement (RA) option
   (called "Boot File URL option") to allow IPv6 routers to advertise
   configuration information for booting a node from the network.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on August 24, 2019.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
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   described in the Simplified BSD License.




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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  Option  . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Boot File Uniform Resource Locator (URL) Option . . . . .   3
   3.  Implementation Considerations . . . . . . . . . . . . . . . .   4
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   This document describes an IPv6 Neighbor Discovery (ND) option
   (called BFURL option) that can be used to provide configuration
   information for nodes to be booted from network instead of local
   media.

   IPv6 Stateless Address Autoconfiguration (SLAAC) [RFC4862] and IPv6
   Neighbor Discovery (ND) [RFC4861] define ways to configure IPv6
   addresses, on-link prefix list, default routers and other parameters.

   The existing ND message (RA) is used to carry this network boot
   information.  Nodes can get the boot file url and parameters through
   RA messages via BFRUL option.  A boot file can be a boot-loader
   program or a minimal OS kernel.  The node firmware needs to download
   the boot file and execute it.

   This approach is useful in networks with no DHCPv6 infrastructure.
   The intention is to simplify the implementation of first-stage
   communicating functionalities of the nodes (i.e.  PXE firmware), and
   network.  The distribution of additional information and subsequent
   communications between the node and network side (e.g., an install
   server) should be handled by applications built in the boot file.

   The configuration of a Boot-File-URL would be required onto routers
   sending RA messages.  The configuration mechanism (manual or
   automatic) is out of scope of this document.

1.1.  Requirements Language

   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 RFC 2119 [RFC2119].



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2.  Option

   The option formats comply with ND options per [RFC4861].

2.1.  Boot File Uniform Resource Locator (URL) Option

   Routers send this option to nodes with a URL to a boot file.

    0                   1                   2                   3
    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     | P-Len |       Reserved1       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           Reserved2                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                Boot-File-URL (variable length)                ~
   |                                                               |
   +               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               |                                               |
   +-+-+-+-+-+-+-+-+     Padding-Data (optional, 0-7 octets)       +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 1

   Fields description:

   Type                    TBD.

   Length                  8-bit unsigned integer.  The length of this
                           option (including the Type and Length fields)
                           in units of 8 octets.

   P-Len                   4-bit unsigned integer.  The length of
                           Padding-Data field in units of octets.

   Reserved1               This field is unused.  It MUST be initialized
                           to zero and MUST be ignored by the receiver.

   Reserved2               This field is unused.  It MUST be initialized
                           to zero and MUST be ignored by the receiver.

   Boot-File-URL           The URL for a boot file in string.  Its
                           format MUST comply with [RFC3986].

   Padding-Data            0-7 octets of zeros for padding the encoding
                           of Boot-File-URL if required.  Since the



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                           length of option MUST be a multiple of 8
                           octets, for the minimum multiple, the
                           remaining octets following the encoding part
                           of Boot-File-URL MUST be padded with zeros.

3.  Implementation Considerations

   In the current format of BFURL option (Section 2.1), there is no
   field defined to identify the architectures of nodes to be booted
   from network.  Implementers should be aware of the details of their
   deployment environment and tailor the boot file to accommodate the
   network booting nodes of different types.

   A new IPv6 Router Solicitation (RS) option can be defined in the
   future for nodes to send the information of architecture types they
   support to the network side for the selection of appropriate boot
   file.

   Also, there is no field defined in the BFURL option nor any
   individual option specified in this document for the network booting
   parameters.  We recommend that, the basic parameters required should
   be embedded in the boot file itself.  That can ease the configuration
   of network booting functionality on the network devices.  After the
   boot file or the built-in application is successfully executed, they
   should take the responsibility of guiding the subsequent phases of
   installation.

   This document puts no constraints on the protocols used to download
   the boot file.  While it is possible that the downloading protocol is
   specified in the URL by syntax.

   Domain names may be used in the boot file URL rather than an IPv6
   address.  That requires the network booting nodes to support DNS
   implementation.  The DNS server information can be also distributed
   by RA options per [RFC8106].

4.  IANA Considerations

   This document requires a new ND option type to be allocated.

   Option Name                     Type

   Boot-File-URL                   TBD.








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5.  Security Considerations

   Rogue RA messages with wrong URL information may be received in the
   untrusted environment and direct the network booting nodes to
   download boot file from an attacker's file server.  The Secure
   Neighbor Discovery (SEND) protocol [RFC3971] is designed to allow all
   ND options including the BFURL option specified in this document to
   be sent with digital signature, which prevent this kind of attack.

   To protect the boot file downloading process, using protocols like
   HTTPS is recommended.  Further, security mechanisms can be
   implemented within the built-in application or the boot file to be
   executed, to secure the communications in the later stage.

6.  Acknowledgements

   The authors would like to thank Jinhui, He Qiang for their comments
   and inputs.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3971]  Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander,
              "SEcure Neighbor Discovery (SEND)", RFC 3971,
              DOI 10.17487/RFC3971, March 2005,
              <https://www.rfc-editor.org/info/rfc3971>.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <https://www.rfc-editor.org/info/rfc3986>.

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              DOI 10.17487/RFC4861, September 2007,
              <https://www.rfc-editor.org/info/rfc4861>.

   [RFC4862]  Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
              Address Autoconfiguration", RFC 4862,
              DOI 10.17487/RFC4862, September 2007,
              <https://www.rfc-editor.org/info/rfc4862>.




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   [RFC8106]  Jeong, J., Park, S., Beloeil, L., and S. Madanapalli,
              "IPv6 Router Advertisement Options for DNS Configuration",
              RFC 8106, DOI 10.17487/RFC8106, March 2017,
              <https://www.rfc-editor.org/info/rfc8106>.

   [UEFI23]   UEFI Forum, "Unified Extensible Firmware Interface (UEFI)
              Specification, Version 2.7 Errata A", August 2017,
              <http://www.uefi.org/>.

7.2.  Informative References

   [RFC3315]  Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
              C., and M. Carney, "Dynamic Host Configuration Protocol
              for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
              2003, <https://www.rfc-editor.org/info/rfc3315>.

   [RFC4578]  Johnston, M. and S. Venaas, Ed., "Dynamic Host
              Configuration Protocol (DHCP) Options for the Intel
              Preboot eXecution Environment (PXE)", RFC 4578,
              DOI 10.17487/RFC4578, November 2006,
              <https://www.rfc-editor.org/info/rfc4578>.

   [RFC5970]  Huth, T., Freimann, J., Zimmer, V., and D. Thaler, "DHCPv6
              Options for Network Boot", RFC 5970, DOI 10.17487/RFC5970,
              September 2010, <https://www.rfc-editor.org/info/rfc5970>.

Authors' Addresses

   Chao Qin (editor)
   Alibaba-Inc
   P.R.China

   Email: jacni@jacni.com


   Yongqing Xi
   Alibaba-Inc
   P.R.China

   Email: yongqing.xyq@alibaba-inc.com


   Wei Xu
   Alibaba-Inc
   P.R.China

   Email: arthur.xw@alibaba-inc.com




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