From 33007e302d2e5b4550fa8c9d5cd1bffaaffb6819 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Petr=20=C5=A0pa=C4=8Dek?= Date: Thu, 16 May 2024 12:15:23 +0200 Subject: [PATCH] Document SIG(0) verification removal --- doc/arm/general.rst | 6 ++---- doc/arm/intro-security.inc.rst | 2 +- doc/arm/reference.rst | 4 ++-- doc/arm/security.inc.rst | 4 ++-- doc/arm/sig0.inc.rst | 16 ++-------------- 5 files changed, 9 insertions(+), 23 deletions(-) diff --git a/doc/arm/general.rst b/doc/arm/general.rst index 09bcaa9725..cabf5c8591 100644 --- a/doc/arm/general.rst +++ b/doc/arm/general.rst @@ -391,10 +391,8 @@ Notes .. [#rfc1035_2] CLASS ANY queries are not supported. This is considered a feature. -.. [#rfc2931] When receiving a query signed with a SIG(0), the server is - only able to verify the signature if it has the key in its local - authoritative data; it cannot do recursion or validation to - retrieve unknown keys. +.. [#rfc2931] Support for SIG(0) message verification was removed + as part of the mitigation of CVE-2024-1975. .. [#rfc2874] Compliance is with loading and serving of A6 records only. A6 records were moved to the experimental category by :rfc:`3363`. diff --git a/doc/arm/intro-security.inc.rst b/doc/arm/intro-security.inc.rst index 87db9701da..996e910a6d 100644 --- a/doc/arm/intro-security.inc.rst +++ b/doc/arm/intro-security.inc.rst @@ -47,7 +47,7 @@ or ports come preconfigured with local (loopback address) security preconfigured If ``rndc`` is being invoked from a remote host, further configuration is required. The ``nsupdate`` tool uses **Dynamic DNS (DDNS)** features and allows users to dynamically change the contents of the zone file(s). ``nsupdate`` access and security may be controlled -using ``named.conf`` :ref:`statements or using TSIG or SIG(0) cryptographic methods `. +using ``named.conf`` :ref:`statements or via the TSIG cryptographic method `. Clearly, if the remote hosts used for either ``rndc`` or DDNS lie within a network entirely under the user's control, the security threat may be regarded as non-existent. Any implementation requirements, therefore, depend on the site's security policy. diff --git a/doc/arm/reference.rst b/doc/arm/reference.rst index 2ddc368514..d6dd932948 100644 --- a/doc/arm/reference.rst +++ b/doc/arm/reference.rst @@ -7450,7 +7450,7 @@ the zone's filename, unless :any:`inline-signing` is enabled. updates are allowed. It specifies a set of rules, in which each rule either grants or denies permission for one or more names in the zone to be updated by one or more identities. Identity is determined by the key - that signed the update request, using either TSIG or SIG(0). In most + that signed the update request, using TSIG. In most cases, :any:`update-policy` rules only apply to key-based identities. There is no way to specify update permissions based on the client source address. @@ -7507,7 +7507,7 @@ the zone's filename, unless :any:`inline-signing` is enabled. field. Details for each rule type are described below. The ``identity`` field must be set to a fully qualified domain name. In - most cases, this represents the name of the TSIG or SIG(0) key that + most cases, this represents the name of the TSIG key that must be used to sign the update request. If the specified name is a wildcard, it is subject to DNS wildcard expansion, and the rule may apply to multiple identities. When a TKEY exchange has been used to diff --git a/doc/arm/security.inc.rst b/doc/arm/security.inc.rst index 878fa379fe..8fc65d3820 100644 --- a/doc/arm/security.inc.rst +++ b/doc/arm/security.inc.rst @@ -85,7 +85,7 @@ Limiting access to the server by outside parties can help prevent spoofing and denial of service (DoS) attacks against the server. ACLs match clients on the basis of up to three characteristics: 1) The -client's IP address; 2) the TSIG or SIG(0) key that was used to sign the +client's IP address; 2) the TSIG key that was used to sign the request, if any; and 3) an address prefix encoded in an EDNS Client-Subnet option, if any. @@ -126,7 +126,7 @@ and no queries at all from the networks specified in ``bogusnets``. In addition to network addresses and prefixes, which are matched against the source address of the DNS request, ACLs may include ``key`` -elements, which specify the name of a TSIG or SIG(0) key. +elements, which specify the name of a TSIG key. When BIND 9 is built with GeoIP support, ACLs can also be used for geographic access restrictions. This is done by specifying an ACL diff --git a/doc/arm/sig0.inc.rst b/doc/arm/sig0.inc.rst index 048dbeae7c..6e6fc3219e 100644 --- a/doc/arm/sig0.inc.rst +++ b/doc/arm/sig0.inc.rst @@ -12,17 +12,5 @@ SIG(0) ------ -BIND partially supports DNSSEC SIG(0) transaction signatures as -specified in :rfc:`2535` and :rfc:`2931`. SIG(0) uses public/private keys to -authenticate messages. Access control is performed in the same manner as with -TSIG keys; privileges can be granted or denied in ACL directives based -on the key name. - -When a SIG(0) signed message is received, it is only verified if -the key is known and trusted by the server. The server does not attempt -to recursively fetch or validate the key. - -SIG(0) signing of multiple-message TCP streams is not supported. - -The only tool shipped with BIND 9 that generates SIG(0) signed messages -is :iscman:`nsupdate`. +Support for DNSSEC SIG(0) transaction signatures has been removed. +This is a countermeasure for CVE-2024-1975.