Re: [Sidrops] revised text for section 6 of 6486bis

[Ties de Kock <[e-mail]>]

Hi all,

I was reading the draft, and I could not understand the intent of Section 6.6,
out of Scope Manifest Entries.

To me, this paragraph seems to be either a leftover from an earlier version of
RFC 6486 (6.1.5/6.1.6) or a reference to Section 2 (manifest scope). In the latter
case, it goes against the notion of just using the manifest to verify that the
publication point contains the files the CA intended to publish.

I would propose to remove the section in its current form, but in that case, I
think we need some text that clarifies how RPs should handle unknown objects.

Kind regards,
Ties


> On 18 Dec 2020, at 17:28, Stephen Kent <stkent=[e-mail]> wrote:
> 
> Based on the numerous comments posted over the past 2+ weeks I have revised the text of section 6 of the document. The revised text focuses exclusively on using a Manifest to ensure that the set of files retrieved from a pub point match those that were posted by the cognizant CA instance.
> 
> Thus, for example, the text no longer requires that the files being retrieved be verified based on RFC 6488.  As a result, there is no need to enumerate the object types that are mandatory to support. Consequently, there is no need to specify how to deal with files that are retrieved but that are not among the mandatory-to-support object types. All of that now belongs in other documents, given the newly-agreed upon scope limitation for Manifest processing.
> 
> For example, the section no longer requires that there be only one CRL, consistent with the notion that the purpose of the manifest is to ensure that the retrieved objects matches what the CA published.
> 
> Because we have removed the object validation constraints from this document, we can no longer state that "The processing described below is designed to cause all RPs with access to the same local cache and RPKI repository data to achieve the same results with regard to validation of RPKI data." Instead, the text now states: " The processing described below is designed to cause all RPs with access to the same local cache and RPKI repository data to acquire the same set of validated repository files. It does not ensure that the RPs will achieve the same results with regard to validation of RPKI data, since that depends on how each RP resolves any conflicts that may arise in processing the retrieved files."
> 
> Steve
> 
> --------
> 
> 
>  <>6.  Relying Party Processing of Manifests
>  
>    Each RP must determine which signed objects it will use for
>    validating assertions about INRs and their use (e.g., which ROAs to
>    use in the construction of route filters).  As noted earlier,
>    manifests are designed to allow an RP to detect manipulation of
>    repository data, errors by a CA or repository manager, and/or active
>    attacks on the communication channel between an RP and a repository.
>    Unless all of the files enumerated in a manifest can be obtained by
>    an RP during a fetch operation, the fetch is considered to have
>    failed and the RP MUST retry the fetch later.
>  
>    [RFC6480] suggests (but does not mandate) that the RPKI model employ
>    fetches that are incremental, e.g., an RP transfers files from a
>    publication point only if they are new/changed since the previous,
>    successful, fetch represented in the RP's local cache.  This document
>    avoids language that relies on details of the underlying file
>    transfer mechanism employed by an RP and a publication point to
>    effect this operation.  Thus the term "fetch" refers to an operation
>    that attempts to acquire the full set of files at a publication
>    point, consistent with the id-ad-rpkiManifest URI extracted from a CA
>    certificate's SIA (see below).
>  
>    If a fetch fails, it is assumed that a subsequent fetch will resolve
>    problems encountered during the fetch.  Until such time as a
>    successful fetch is executed, an RP SHOULD use cached data from a
>    previous, successful fetch.  This response is intended to prevent an
>    RP from misinterpreting data associated with a publication point, and
>    thus possibly treating invalid routes as valid, or vice versa.
>  
>    The processing described below is designed to cause all RPs with
>    access to the same local cache and RPKI repository data to acquire
>    the same set of validated repository files. It does not ensure that
>    the RPs will achieve the same results with regard to validation of 
>    RPKI data, since that depends on how each RP resolves any conflicts 
>    that may arise in processing the retrieved files. Moreover, in 
>    operation, different RPs will access repositories at different times,
>    and some RPs may experience local cache failures, so there is no
>    guarantee that all RPs will achieve the same results with regard to
>    acquisition or validation of RPKI data.
>  
>    Note also that there is a "chicken and egg" relationship between the
>    manifest and the CRL for a given CA instance.  If the EE certificate
>    for the current manifest is revoked, i.e., it appears in the current
>    CRL, then the CA or publication point manager has made a serious
>    error.  In this case the fetch has failed; proceed to Section 6.7.
>    Similarly, if the CRL is not listed on a valid, current manifest,
>    acquired during a fetch, the fetch has failed; proceed to
>    Section 6.7, because the CRL is considered missing.
>  
>  
>  
>  
> 6.1.  Manifest Processing Overview
>  
>    For a given publication point, an RP MUST perform a series of tests
>    to determine which signed object files at the publication point are
>    acceptable.  The tests described below (Section 6.2 to Section 6.6)
>    are to be performed using the manifest identified by the id-ad-
>    rpkiManifest URI extracted from a CA certificate's SIA.  All of the
>    files referenced by the manifest MUST be located at the
>    publication point specified by the id-ad-caRepository URI from the
>    (same) CA certificate's SIA.  The manifest and the files it
>    references MUST reside at the same publication point.  If an RP
>    encounters any files that appear on a manifest but do not reside at
>    the same publication point as the manifest the RP MUST treat the
>    fetch as failed, and a warning MUST be issued (see Section 6.7
>    below).
>  
>    Note that, during CA key rollover [RFC6489], signed objects for two
>    or more different CA instances will appear at the same publication
>    point.  Manifest processing is to be performed separately for each CA
>    instance, guided by the SIA id-ad-rpkiManifest URI in each CA
>    certificate.
>  
> 6.2.  Acquiring a Manifest for a CA
>  
>    The RP MUST fetch the manifest identified by the SIA id-ad-
>    rpkiManifest URI in the CA certificate.  If an RP cannot retrieve a
>    manifest using this URI, or if the manifest is not valid
>    (Section 4.4), an RP MUST treat this as a failed fetch and, proceed
>    to Section 6.7; otherwise proceed to Section 6.3.
>  
> 6.3.  Detecting Stale and or Prematurely-issued Manifests
>  
>    The RP MUST check that the current time (translated to UTC) is
>    between thisUpdate and nextUpdate.  If the current time lies within
>    this interval, proceed to Section 6.4.  If the current time is
>    earlier than thisUpdate, the CA has made an error; this is a failed
>    fetch and the RP MUST proceed to Section 6.7.  If the current time is
>    later than nextUpdate, then the manifest is stale; this is a failed
>    fetch and RP MUST proceed to Section 6.7; otherwise proceed to
>    Section 6.4.
>  
>  
>  
> 6.4.  Acquiring Files Referenced by a Manifest
>  
>    The RP MUST acquire all of the files enumerated in the manifest
>    (fileList) from the publication point. If there are files listed in
>    the manifest that cannot be retrieved from the publication point, the 
>    fetch has failed and the RP MUST proceed to Section 6.7; otherwise, 
>    proceed to Section 6.5
>  
>  
> 6.5.  Matching File Names and Hashes
>  
>    The RP MUST verify that the hash value of each file listed in the
>    manifest matches the value obtained by hashing the file acquired from
>    the publication point.  If the computed hash value of a file listed
>    on the manifest does not match the hash value contained in the
>    manifest, then the fetch has failed and the RP MUST proceed to
>    Section 6.7; otherwise proceed to Section 6.6.
>  
> 6.6.  Out of Scope Manifest Entries
>  
>    If a current manifest contains entries for objects that are not
>    within the scope of the manifest (Section 6.2), the fetch has failed
>    and the RP SHOULD proceed to Section 6.7; otherwise the fetch is
>    deemed successful and the RP will process the fetched objects.
>  
> 6.7.  Failed Fetches
>  
>    If a fetch fails for any of the reasons cited in 6.2-6.6, the RP MUST 
>    issue a warning indicating the reason(s)for termination of processing
>    with regard to this CA instance.  It is RECOMMENDED that a human 
>    operator be notified of this warning.
>  
>    Termination of processing means that the RP SHOULD continue to use
>    cached versions of the objects associated with this CA instance,
>    until such time as they become stale or they can be replaced by
>    objects from a successful fetch.  This implies that the RP MUST not
>    try to acquire and validate subordinate signed objects, e.g.,
>    subordinate CA certificates, until the next interval when the RP is
>    scheduled to fetch and process data for this CA instance.
>  
> 
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