idnits 2.17.1 draft-wood-httpbis-ech-coalescing-00.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The abstract seems to contain references ([RFC7540]), which it shouldn't. Please replace those with straight textual mentions of the documents in question. -- The abstract seems to indicate that this document updates RFC7540, but the header doesn't have an 'Updates:' line to match this. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (7 March 2022) is 780 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-12) exists of draft-ietf-dnsop-svcb-https-08 ** Obsolete normative reference: RFC 7540 (Obsoleted by RFC 9113) == Outdated reference: A later version (-18) exists of draft-ietf-tls-esni-14 Summary: 2 errors (**), 0 flaws (~~), 3 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 httpbis C. A. Wood 3 Internet-Draft Cloudflare 4 Intended status: Standards Track 7 March 2022 5 Expires: 8 September 2022 7 HTTP Connection Reuse Based on TLS Encrypted ClientHello 8 draft-wood-httpbis-ech-coalescing-00 10 Abstract 12 This document specifies new criteria under which HTTP/2 clients may 13 reuse connections. It updates [RFC7540]. 15 Discussion Venues 17 This note is to be removed before publishing as an RFC. 19 Source for this draft and an issue tracker can be found at 20 https://github.com/chris-wood/draft-wood-httpbis-ech-coalescing. 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at https://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on 8 September 2022. 39 Copyright Notice 41 Copyright (c) 2022 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 46 license-info) in effect on the date of publication of this document. 47 Please review these documents carefully, as they describe your rights 48 and restrictions with respect to this document. Code Components 49 extracted from this document must include Revised BSD License text as 50 described in Section 4.e of the Trust Legal Provisions and are 51 provided without warranty as described in the Revised BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 56 2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3 57 3. ECH-Based Coalescing Policy . . . . . . . . . . . . . . . . . 3 58 4. HTTP/3 Reuse . . . . . . . . . . . . . . . . . . . . . . . . 3 59 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 60 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 61 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 62 7.1. Normative References . . . . . . . . . . . . . . . . . . 4 63 7.2. Informative References . . . . . . . . . . . . . . . . . 4 64 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 5 65 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5 67 1. Introduction 69 The HTTP/2 connection reuse policy requires is stated as follows: 71 Connections that are made to an origin server, either directly or 72 through a tunnel created using the CONNECT method (Section 8.3), MAY 73 be reused for requests with multiple different URI authority 74 components. A connection can be reused as long as the origin server 75 is authoritative (Section 10.1). For TCP connections without TLS, 76 this depends on the host having resolved to the same IP address. 78 For "https" resources, connection reuse additionally depends on 79 having a certificate that is valid for the host in the URI. The 80 certificate presented by the server MUST satisfy any checks that the 81 client would perform when forming a new TLS connection for the host 82 in the URI. 84 Thus, HTTPS connections require that the target resource hostname 85 resolve to an IP address that matches that of the candidate 86 connection for coalescing. This IP address match ensures that 87 clients connect to the same service. If a server changes IP 88 addresses as a means of mitigating hostname-to-IP bindings, clients 89 are less likely to reuse connections. This can have performance 90 problems, due to requiring an extra connection setup phase, as well 91 as privacy problems. 93 In short, using unauthenticated IP addresses as a signal for 94 connection reuse is fragile. This document relaxes this requirement 95 and introduces another signal based on HTTPS RR answer contents 96 [HTTPS-RR]. 98 2. Conventions and Definitions 100 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 101 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 102 "OPTIONAL" in this document are to be interpreted as described in 103 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all 104 capitals, as shown here. 106 3. ECH-Based Coalescing Policy 108 The HTTPS RR [HTTPS-RR] is a new resource record used for conveying 109 service information about a HTTPS endpoint to clients. Some of this 110 information includes, for example, TLS Encrypted ClientHello (ECH) 111 [TLS-ECH] public key material. The set of hosts behind the same ECH 112 client-facing service provider that share the same ECH and TLS 113 configuration information is referred to as the anonymity set. 114 Client-facing servers SHOULD deploy ECH in such a way so as to 115 maximize the size of the anonymity set where possible. This means 116 client-facing servers should use the same ECH configuration 117 (ECHConfig) for as many hosts as possible. 119 This type of deployment model means that a given ECHConfig uniquely 120 identifies a given service provider. As a result, clients can use it 121 as a signal to determine if a given resource is hosted by the same 122 service provider. Thus, the HTTP/2 connection reuse policy is 123 modified to use this signal as follows: 125 Connections that are made to an origin server, either directly or 126 through a tunnel created using the CONNECT method (Section 8.3), 127 MAY be reused for requests with multiple different URI authority 128 components. A connection can be reused as long as the origin 129 server is authoritative (Section 10.1). For TCP connections 130 without TLS, this depends on the host having resolved to the same 131 service provider. Clients may implement this check in one of two 132 ways: (1) by comparing for equality the resolved IP address to 133 that of the original connection, or (2) by comparing for equality 134 the "ech" SvcParamValue in the resolved HTTPS RR answer. For the 135 latter case, the original connection MUST have successfully used 136 the "ech" parameter to negotiate TLS ECH. 138 4. HTTP/3 Reuse 140 The HTTP/3 connection reuse policy [HTTP3] does not require IP 141 addresses to match. However, as HTTP/3 is based on UDP, some clients 142 may fall back to HTTP/2 over TCP in networks where UDP is blocked or 143 otherwise inoperable. Thus, the policy described in this document 144 only applies to HTTP/2. 146 5. Security Considerations 148 Existing coalescing policies do not require IP address authentication 149 via DNSSEC. Thus, an adversary which can spoof A or AAAA responses 150 can equally spoof HTTPS responses and ECHConfigList values. 152 6. IANA Considerations 154 This document has no IANA actions. 156 7. References 158 7.1. Normative References 160 [HTTPS-RR] Schwartz, B., Bishop, M., and E. Nygren, "Service binding 161 and parameter specification via the DNS (DNS SVCB and 162 HTTPS RRs)", Work in Progress, Internet-Draft, draft-ietf- 163 dnsop-svcb-https-08, 12 October 2021, 164 . 167 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 168 Requirement Levels", BCP 14, RFC 2119, 169 DOI 10.17487/RFC2119, March 1997, 170 . 172 [RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext 173 Transfer Protocol Version 2 (HTTP/2)", RFC 7540, 174 DOI 10.17487/RFC7540, May 2015, 175 . 177 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 178 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 179 May 2017, . 181 [TLS-ECH] Rescorla, E., Oku, K., Sullivan, N., and C. A. Wood, "TLS 182 Encrypted Client Hello", Work in Progress, Internet-Draft, 183 draft-ietf-tls-esni-14, 13 February 2022, 184 . 187 7.2. Informative References 189 [HTTP3] Bishop, M., "Hypertext Transfer Protocol Version 3 190 (HTTP/3)", Work in Progress, Internet-Draft, draft-ietf- 191 quic-http-34, 2 February 2021, 192 . 195 Acknowledgments 197 This document was improved based on feedback from David Benjamin, 198 Tommy Pauly, and Martin Thomson. 200 Author's Address 202 Christopher A. Wood 203 Cloudflare 204 Email: caw@heapingbits.net