Internet DRAFT - draft-herbert-ipv6-srh-ah
draft-herbert-ipv6-srh-ah
INTERNET-DRAFT T. Herbert
Intended Status: Standard Quantonium
Expires: November 2019
May 27, 2019
IPv6 Authentication Header with Segment Routing Header Processing
draft-herbert-ipv6-srh-ah-00
Abstract
This specification describes processing of the IPv6 Authentication
Header when the IPv6 Segment Routing Header is present in the same
packet. Specifically, the handling of mutable fields in the Segment
Routing Header for the purposes of computing or verifying the
packet's authenticating value is specified.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and 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/1id-abstracts.html
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html
Copyright and License Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
T. Herbert Expires November 28, 2019 [Page 1]
INTERNET DRAFT draft-herbert-ipv6-srh-ah-00 May 27, 2019
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Handling mutable fields in AH . . . . . . . . . . . . . . . 3
1.2 Mutable fields in Segment Routing Header . . . . . . . . . . 3
2 Handling mutable SRH fields for ICV calculation . . . . . . . . 4
3 Security Considerations . . . . . . . . . . . . . . . . . . . . 5
4 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
5 References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.1 Normative References . . . . . . . . . . . . . . . . . . . 5
5.2 Informative References . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5
T. Herbert Expires November 28, 2019 [Page 2]
INTERNET DRAFT draft-herbert-ipv6-srh-ah-00 May 27, 2019
1 Introduction
This specification describes processing of the IPv6 Authentication
Header (AH) [RFC4302] when the IPv6 Segment Routing Header (SRH)
[SRH] is present in the same packet. AH is used to authenticate the
preceding IPv6 header and extension headers in a packet.
Authentication is performed by computing an Integrity Check Value
(ICV) over the covered headers and comparing the computed value to
that contained in the ICV field of the AH header. Both the sender and
receiver (the final destination in the case that a routing header is
present) MUST independently and deterministically perform the same
computation over the same data.
1.1 Handling mutable fields in AH
Certain fields may be modified during transit (i.e. mutable fields).
To ensure that the sender and receiver both produce the same result
in ICV computation for mutable fields, Section 5.3.3.1 of [RFC4302]
specifies:
* If a field is mutable and its value at the (IPsec) receiver is
not predictable, then the value of the field is set to zero for
purposes of the ICV computation.
* If a field is mutable and its value at the (IPsec) receiver is
predictable, then the predicted value is inserted into the field
for purposes of the ICV computation.
1.2 Mutable fields in Segment Routing Header
Per [RFC8200] and [SRH], there are three instances of mutable fields
related to segment routing:
* IPv6 destination address: The value of the destination address
is predicable at the receiver. This is the last address in the
segment routing list (destination address set when segments left
goes to zero).
* Segments left: This is a field in the routing header and it's
value is predictable at the receiver. The field's value is
decremented at each intermediate destination such that the value
at the final destination will be zero.
* Mutable SRH TLVs: Per [SRH], if the high order bit of an SRH TLV
type is set then the TLV data for the corresponding TLV is
mutable. The value of the TLV data for a mutable TLV is not
predictable at the receiver.
T. Herbert Expires November 28, 2019 [Page 3]
INTERNET DRAFT draft-herbert-ipv6-srh-ah-00 May 27, 2019
2 Handling mutable SRH fields for ICV calculation
When performing the ICV calculation, at either the sender or
receiver, the following values are set in the packet for the purpose
of the calculation when an SRH header is present:
* The IPv6 destination address is set to final address in the
segment routing list.
* Segments left field in the routing header is set to zero.
* For any SRH TLV whose high order bit is set, set the
corresponding TLV data to all zeroes.
In pseudo code this is:
/* opt is a char pointer to the segment routing header,
* iph is a pointer to the IP header of the packet
*/
/* Set segments left to zero */
if (opt[3] != 0) {
opt[3] = 0
/* Set destination to final address */
iph->dest_address = *(struct ipv6_address *)&opt[8]
}
/* Determine offset of TLVs */
off = 8 + (opt[4] << 4)
len = ((opt[1] + 1) << 3) - off
/* Zero data for mutable TLVs */
while (len > 0) {
if (opt[off] == 0) {
optlen = 1
} else {
if (opt[off] & 0x80)
memset(&opt[off + 2], 0, opt[off + 1])
optlen = opt[off + 1] + 2
}
off += optlen
len -= optlen
}
T. Herbert Expires November 28, 2019 [Page 4]
INTERNET DRAFT draft-herbert-ipv6-srh-ah-00 May 27, 2019
3 Security Considerations
The subject of this document is security using Segment Routing Header
with the Authentication Header.
4 IANA Considerations
There are no IANA considerations in this document.
5 References
5.1 Normative References
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200, DOI
10.17487/RFC8200, July 2017, <https://www.rfc-
editor.org/info/rfc8200>.
[RFC4302] Kent, S., "IP Authentication Header", RFC 4302, DOI
10.17487/RFC4302, December 2005, <https://www.rfc-
editor.org/info/rfc4302>.
[SRH] C. Filsfils, Ed., D. Dukes, Ed., S. Previdi, J. Leddy, S.
Matsushima, D. Voyer, Ed., "IPv6 Segment Routing Header
(SRH)", draft-ietf-6man-segment-routing-header-19
5.2 Informative References
Author's Address
Tom Herbert
Quantonium
Santa Clara, CA
USA
Email: tom@quantonium.net
T. Herbert Expires November 28, 2019 [Page 5]
