draft-ietf-sidr-rpki-tree-validation-01.txt   draft-ietf-sidr-rpki-tree-validation-02.txt 
SIDR O. Muravskiy SIDR O. Muravskiy
Internet-Draft T. Bruijnzeels Internet-Draft T. Bruijnzeels
Intended status: Informational RIPE NCC Intended status: Informational RIPE NCC
Expires: January 9, 2017 July 8, 2016 Expires: January 21, 2017 July 20, 2016
RPKI Certificate Tree Validation by a Relying Party Tool RPKI Certificate Tree Validation by a Relying Party Tool
draft-ietf-sidr-rpki-tree-validation-01 draft-ietf-sidr-rpki-tree-validation-02
Abstract Abstract
This document describes the approach to validate the content of the This document describes the approach to validate the content of the
RPKI certificate tree, as used by the RIPE NCC RPKI Validator. This RPKI certificate tree, as used by the RIPE NCC RPKI Validator. This
approach is independent of a particular object retrieval mechanism. approach is independent of a particular object retrieval mechanism.
This allows it to be used with repositories available over the rsync This allows it to be used with repositories available over the rsync
protocol, the RPKI Repository Delta Protocol, and repositories that protocol, the RPKI Repository Delta Protocol, and repositories that
use a mix of both. use a mix of both.
This algorithm does not rely on content of repository directories,
but uses the Authority Key Identifier (AKI) field of a manifest and a
certificate revocation list (CRL) objects to discover manifest and
CRL objects issued by a particular Certificate Authority (CA). It
further uses the hashes of manifest entries to discover other objects
issued by the CA.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on January 9, 2017. This Internet-Draft will expire on January 21, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. General Considerations . . . . . . . . . . . . . . . . . . . 3 2. General Considerations . . . . . . . . . . . . . . . . . . . 3
2.1. Hash comparisons . . . . . . . . . . . . . . . . . . . . 3 2.1. Hash comparisons . . . . . . . . . . . . . . . . . . . . 3
2.2. Manifest entries versus repository content . . . . . . . 4 2.2. Discovery of RPKI objects issued by a CA . . . . . . . . 3
2.3. Manifest entries versus repository content . . . . . . . 4
3. Top-down Validation of a Single Trust Anchor Certificate Tree 4 3. Top-down Validation of a Single Trust Anchor Certificate Tree 4
3.1. Fetching the Trust Anchor Certificate Using the Trust 3.1. Fetching the Trust Anchor Certificate Using the Trust
Anchor Locator . . . . . . . . . . . . . . . . . . . . . 4 Anchor Locator . . . . . . . . . . . . . . . . . . . . . 5
3.2. Resource Certificate Validation . . . . . . . . . . . . . 5 3.2. CA Certificate Validation . . . . . . . . . . . . . . . . 5
3.2.1. Finding the most recent valid manifest and CRL . . . 6 3.2.1. Finding the most recent valid manifest and CRL . . . 6
3.2.2. Manifest entries validation . . . . . . . . . . . . . 7 3.2.2. Manifest entries validation . . . . . . . . . . . . . 7
3.3. Object Store Cleanup . . . . . . . . . . . . . . . . . . 7 3.3. Object Store Cleanup . . . . . . . . . . . . . . . . . . 8
4. Remote Objects Fetcher . . . . . . . . . . . . . . . . . . . 8 4. Remote Objects Fetcher . . . . . . . . . . . . . . . . . . . 8
4.1. Fetcher Operations . . . . . . . . . . . . . . . . . . . 8 4.1. Fetcher Operations . . . . . . . . . . . . . . . . . . . 8
4.1.1. Fetch repository objects . . . . . . . . . . . . . . 8 4.1.1. Fetch repository objects . . . . . . . . . . . . . . 9
4.1.2. Fetch single repository object . . . . . . . . . . . 9 4.1.2. Fetch single repository object . . . . . . . . . . . 9
5. Local Object Store . . . . . . . . . . . . . . . . . . . . . 9 5. Local Object Store . . . . . . . . . . . . . . . . . . . . . 10
5.1. Store Operations . . . . . . . . . . . . . . . . . . . . 9 5.1. Store Operations . . . . . . . . . . . . . . . . . . . . 10
5.1.1. Store Repository Object . . . . . . . . . . . . . . . 9 5.1.1. Store Repository Object . . . . . . . . . . . . . . . 10
5.1.2. Get objects by hash . . . . . . . . . . . . . . . . . 9 5.1.2. Get objects by hash . . . . . . . . . . . . . . . . . 10
5.1.3. Get certificate objects by URI . . . . . . . . . . . 10 5.1.3. Get certificate objects by URI . . . . . . . . . . . 10
5.1.4. Get manifest objects by AKI . . . . . . . . . . . . . 10 5.1.4. Get manifest objects by AKI . . . . . . . . . . . . . 10
5.1.5. Delete objects for a URI . . . . . . . . . . . . . . 10 5.1.5. Delete objects for a URI . . . . . . . . . . . . . . 10
5.1.6. Delete outdated objects . . . . . . . . . . . . . . . 10 5.1.6. Delete outdated objects . . . . . . . . . . . . . . . 10
5.1.7. Update object's validation time . . . . . . . . . . . 10 5.1.7. Update object's validation time . . . . . . . . . . . 11
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
8. Security Considerations . . . . . . . . . . . . . . . . . . . 10 8. Security Considerations . . . . . . . . . . . . . . . . . . . 11
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
9.1. Normative References . . . . . . . . . . . . . . . . . . 11 9.1. Normative References . . . . . . . . . . . . . . . . . . 12
9.2. Informative References . . . . . . . . . . . . . . . . . 12 9.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction 1. Introduction
In order to use information published in RPKI repositories, Relying In order to use information published in RPKI repositories, Relying
Parties (RP) need to retrieve and validate the content of Parties (RP) need to retrieve and validate the content of
certificates, CRLs, and other RPKI signed objects. To validate a certificates, CRLs, and other RPKI signed objects. To validate a
particular object, one must ensure that all certificates in the particular object, one must ensure that all certificates in the
certificate chain up to the Trust Anchor (TA) are valid. Therefore certificate chain up to the Trust Anchor (TA) are valid. Therefore
the validation of a certificate tree is usually performed top-down, the validation of a certificate tree is performed top-down, starting
starting from the TA certificate and descending down the certificate from the TA certificate and descending down the certificate chain,
chain, validating every encountered certificate and its products. validating every encountered certificate and its products. The
The result of this process is a list of all encountered RPKI objects result of this process is a list of all encountered RPKI objects with
with a validity status attached to each of them. These results may a validity status attached to each of them. These results may later
later be used by a Relying Party in taking routing decisions, etc. be used by a Relying Party in taking routing decisions, etc.
Traditionally RPKI data is made available to RPs through the Traditionally RPKI data is made available to RPs through the
repositories [RFC6481] accessible over rsync protocol. Relying repositories [RFC6481] accessible over rsync protocol. Relying
parties are advised to keep a local copy of repository data, and parties are advised to keep a local copy of repository data, and
perform regular updates of this copy from the repository (Section 5 perform regular updates of this copy from the repository (Section 5
of [RFC6481]). The RPKI Repository Delta Protocol of [RFC6481]). The RPKI Repository Delta Protocol
[I-D.ietf-sidr-delta-protocol] introduces another method to fetch [I-D.ietf-sidr-delta-protocol] introduces another method to fetch
repository data and keep the local copy up to date with the repository data and keep the local copy up to date with the
repository. repository.
This document describes how the RIPE NCC RPKI Validator discovers This document describes how the RIPE NCC RPKI Validator discovers
RPKI objects to download, builds certificate paths, and validates RPKI objects to download, builds certificate paths, and validates
RPKI objects, independently from what repository access protocol is RPKI objects, independently from what repository access protocol is
used. To achieve this, it puts downloaded RPKI objects in an object used. To achieve this, it puts downloaded RPKI objects in an object
store, where objects could be found by their URI, hash of their store, where each RPKI object can be found by its URI, the hash of
content, value of the object's AKI field, or combination of these. its content, value of its Authority Key Identifier (AKI) extension,
It also keeps track of download and validation time for every object, or a combination of these. It also keeps track of the download and
to perform cleanups of the local copy. the validation time for every object, to perform cleanups of the
local copy.
2. General Considerations 2. General Considerations
2.1. Hash comparisons 2.1. Hash comparisons
This algorithm relies on the properties of the file hash algorithm This algorithm relies on the properties of the file hash algorithm
(defined in [RFC6485]) to compute the hash of repository objects. It (defined in [RFC6485]) to compute the hash of repository objects. It
assumes that any two objects for which the hash value is the same, assumes that any two objects for which the hash value is the same,
are identical. are identical.
The hash comparison is used when matching objects in the repository The hash comparison is used when matching objects in the repository
with entries on the manifest, and when looking up objects in the with entries on the manifest, and when looking up objects in the
object store (Section 5). object store (Section 5).
2.2. Manifest entries versus repository content 2.2. Discovery of RPKI objects issued by a CA
There are several possible ways of discovering products of a CA There are several possible ways of discovering products of a CA
certificate: one could use all objects located in a repository certificate: one could use all objects located in a repository
directory designated as a publication point for a CA, or only objects directory designated as a publication point for a CA, or only objects
mentioned on the manifest located at that publication point (see mentioned on the manifest located at that publication point (see
Section 6 of [RFC6486]), or use all objects whose AKI field matches Section 6 of [RFC6486]), or use all objects whose AKI extension
the SKI field of a CA certificate. matches the Subject Key Identifier (SKI) extension (Section 4.2.1 of
[RFC5280]) of a CA certificate.
For publication points whose content is consistent with the manifest
and issuing certificate all of these approaches should produce the
same result. For inconsistent publication points the results might
be different. Section 6 of [RFC6486] leaves the decision on how to
deal with inconsistencies to a local policy.
The implementation described here does not rely on content of
repository directories, but uses the Authority Key Identifier (AKI)
extension of a manifest and a certificate revocation list (CRL) to
find in an object store (Section 5) a manifest and a CRL issued by a
particular Certification Authority (CA) (see Section 3.2.1). It
further uses the hashes of manifest's fileList entries (Section 4.2.1
of [RFC6486]) to find other objects issued by the CA, as described in
Section 3.2.2.
2.3. Manifest entries versus repository content
Since the current set of RPKI standards requires use of the manifest Since the current set of RPKI standards requires use of the manifest
[RFC6486] to describe the content of a publication point, this [RFC6486] to describe the content of a publication point, this
implementation requires a consistency between the publication point implementation requires strict consistency between the publication
content and manifest content. Therefore it will not use in the point content and manifest content. (This is a more stringent
validation process objects that are found in the publication point requirement than established in [RFC6486].) Therefore it will not
but do not match any of the entries of that publication point's process objects that are found in the publication point but do not
manifest (see Section 3.2.2). It will also issue warnings for all match any of the entries of that publication point's manifest (see
found mismatches, so that the responsible operators could be made Section 3.2.2). It will also issue warnings for all found
aware of inconsistencies and fix them. mismatches, so that the responsible operators could be made aware of
inconsistencies and fix them.
3. Top-down Validation of a Single Trust Anchor Certificate Tree 3. Top-down Validation of a Single Trust Anchor Certificate Tree
1. The validation of a Trust Anchor (TA) certificate tree starts 1. The validation of a Trust Anchor (TA) certificate tree starts
from its TA certificate. To retrieve the TA certificate, a Trust from its TA certificate. To retrieve the TA certificate, a Trust
Anchor Locator (TAL) object is used, as described in Section 3.1. Anchor Locator (TAL) object is used, as described in Section 3.1.
2. If the TA certificate is retrieved, it is validated according to 2. If the TA certificate is retrieved, it is validated according to
the Section 7 of [RFC6487] and Section 2.2 of [RFC7730]. Section 7 of [RFC6487] and Section 2.2 of [RFC7730]. Otherwise
the validation of certificate tree is aborted and an error is
issued.
3. If the TA certificate is valid, then all its subordinate objects 3. If the TA certificate is valid, then all its subordinate objects
are validated as described in Section 3.2. Otherwise the are validated as described in Section 3.2. Otherwise the
validation of certificate tree is aborted and an error is issued. validation of certificate tree is aborted and an error is issued.
4. For all repository objects that were validated during this 4. For each repository object that was validated during this
validation run, their validation timestamp is updated in an validation run, its validation timestamp is updated in the object
object store (see Section 5.1.7). store (see Section 5.1.7).
5. Outdated objects are removed from the store as described in 5. Outdated objects are removed from the store as described in
Section 3.3. This completes the validation of the TA certificate Section 3.3. This completes the validation of the TA certificate
tree. tree.
3.1. Fetching the Trust Anchor Certificate Using the Trust Anchor 3.1. Fetching the Trust Anchor Certificate Using the Trust Anchor
Locator Locator
The following steps are performed in order to fetch the Trust Anchor The following steps are performed in order to fetch a Trust Anchor
Certificate: Certificate:
1. (Optional) If the Trust Anchor Locator contains a "prefetch.uris" 1. (Optional) If the Trust Anchor Locator contains a "prefetch.uris"
field, pass the URIs contained in that field to the fetcher (see field, pass the URIs contained in that field to the fetcher (see
Section 4.1.1). (This field is a non-standard extension to the Section 4.1.1). (This field is a non-standard addition to the
TAL format. It helps fetching non-hierarchical rsync TAL format. It helps fetching non-hierarchical rsync
repositories more efficiently.) repositories more efficiently.)
2. Extract the TA certificate URI from the TAL's URI section (see 2. Extract the TA certificate URI from the TAL's URI section (see
Section 2.1 of [RFC7730]) and pass it to the object fetcher Section 2.1 of [RFC7730]) and pass it to the object fetcher
(Section 4.1.2). (Section 4.1.2).
3. Retrieve from the object store (see Section 5.1.3) all 3. Retrieve from the object store (see Section 5.1.3) all
certificate objects, for which the URI matches the URI extracted certificate objects, for which the URI matches the URI extracted
from the TAL in the previous step, and the public key matches the from the TAL in the previous step, and the public key matches the
subjectPublicKeyInfo field of the TAL (see Section 2.1 of subjectPublicKeyInfo extension of the TAL (see Section 2.1 of
[RFC7730]). [RFC7730]).
4. If no, or more than one such objects are found, issue an error 4. If no, or more than one such objects are found, issue an error
and abort certificate tree validation process with an error. and abort certificate tree validation process with an error.
Otherwise, use the single found object as the Trust Anchor Otherwise, use the single found object as the Trust Anchor
certificate. certificate.
3.2. Resource Certificate Validation 3.2. CA Certificate Validation
The following steps describe the validation of a single resource The following steps describe the validation of a single CA Resource
certificate: certificate:
1. If both the caRepository (Section 4.8.8.1 of [RFC6487]), and the 1. If both the caRepository (Section 4.8.8.1 of [RFC6487]), and the
id-ad-rpkiNotify (Section 3.5 of [I-D.ietf-sidr-delta-protocol]) id-ad-rpkiNotify (Section 3.2 of [I-D.ietf-sidr-delta-protocol])
SIA pointers are present in the given resource certificate, use a SIA pointers are present in the CA certificate, use a local
local policy to determine which pointer to use. Extract the URI policy to determine which pointer to use. Extract the URI from
from the selected pointer and pass it to the object fetcher (see the selected pointer and pass it to the object fetcher (see
Section 4.1.1). Section 4.1.1).
2. For a given resource certificate, find its manifest and 2. For the CA certificate, find the current manifest and certificate
certificate revocation list (CRL), using the procedure described revocation list (CRL), using the procedure described in
in Section 3.2.1. If no such manifest and CRL could be found, Section 3.2.1. If no such manifest and CRL could be found, stop
stop validation of this certificate, consider it invalid, and validation of this certificate, consider it invalid, and issue an
issue an error. error.
3. Compare the URI found in the given resource certificate's id-ad- 3. Compare the URI found in the id-ad-rpkiManifest field
rpkiManifest field (Section 4.8.8.1 of [RFC6487]) with the URI of (Section 4.8.8.1 of [RFC6487]) of the SIA extension of the
the manifest found in the previous step. If they are different, certificate with the URI of the manifest found in the previous
issue a warning. step. If they are different, issue a warning.
4. Perform manifest entries discovery and validation as described in 4. Perform manifest entries discovery and validation as described in
Section 3.2.2. Section 3.2.2.
5. Validate all resource certificate objects found on the manifest, 5. Validate all resource certificate objects found on the manifest,
using the CRL object found on the manifest, according to using the CRL object found on the manifest, according to
Section 7 of [RFC6487]. Section 7 of [RFC6487].
6. Validate all ROA objects found on the manifest, using the CRL 6. Validate all ROA objects found on the manifest, using the CRL
object found on the manifest, according to the Section 4 of object found on the manifest, according to Section 4 of
[RFC6482]. [RFC6482].
7. Validate all Ghostbusters Record objects found on the manifest, 7. Validate all Ghostbusters Record objects found on the manifest,
using the CRL object found on the manifest, according to the using the CRL object found on the manifest, according to
Section 7 of [RFC6493]. Section 7 of [RFC6493].
8. For every valid resource certificate object found on the 8. For every valid CA certificate object found on the manifest,
manifest, apply the procedure described in this section apply the procedure described in this section (Section 3.2),
(Section 3.2), recursively, provided that this resource recursively, provided that this CA certificate (identified by its
certificate (identified by its SKI) has not yet been validated SKI) has not yet been validated during current tree validation
during current repository validation run. run.
3.2.1. Finding the most recent valid manifest and CRL 3.2.1. Finding the most recent valid manifest and CRL
1. Fetch from the store (see Section 5.1.4) all objects of type 1. Fetch from the store (see Section 5.1.4) all objects of type
manifest, whose certificate's AKI field matches the SKI of the manifest, whose certificate's AKI extension matches the SKI of
current CA certificate. If no such objects are found, stop the current CA certificate. If no such objects are found, stop
processing current resource certificate and issue an error. processing the current CA certificate and issue an error.
2. Find among found objects the manifest object with the highest 2. Find among found objects the manifest object with the highest
manifestNumber field (Section 4.2.1 of [RFC6486]), for which all manifestNumber field (Section 4.2.1 of [RFC6486]), for which all
following conditions are met: following conditions are met:
* There is only one entry in the manifest for which the store * There is only one entry in the manifest for which the store
contains exactly one object of type CRL, whose hash matches contains exactly one object of type CRL, the hash of which
the hash of the entry. matches the hash of the entry.
* The manifest's certificate AKI equals the above CRL's AKI. * The manifest's certificate AKI equals the above CRL's AKI.
* The above CRL is a valid object according to Section 6.3 of * The above CRL is a valid object according to Section 6.3 of
[RFC5280]. [RFC5280].
* The manifest is a valid object according to Section 4.4 of * The manifest is a valid object according to Section 4.4 of
[RFC6486], using the CRL found above. [RFC6486], and its EE certificates is not in the CRL found
above.
3. If there is an object that matches above criteria, consider this 3. If there is an object that matches above criteria, consider this
object to be the valid manifest, and the CRL found at the object to be the valid manifest, and the CRL found at the
previous step - the valid CRL for the current CA certificate's previous step - the valid CRL for the current CA certificate's
publication point. publication point.
4. Report an error for every other manifest with a number higher 4. Report an error for every other manifest with a number higher
than the number of the valid manifest. than the number of the valid manifest.
3.2.2. Manifest entries validation 3.2.2. Manifest entries validation
skipping to change at page 7, line 24 skipping to change at page 7, line 32
3. If no such objects are found, issue an error for this manifest 3. If no such objects are found, issue an error for this manifest
entry and progress to the next entry. This case indicates that entry and progress to the next entry. This case indicates that
the repository does not have an object at the location listed in the repository does not have an object at the location listed in
the manifest, or that the object's hash does not match the hash the manifest, or that the object's hash does not match the hash
listed in the manifest. listed in the manifest.
4. For every found object, compare its URI with the URI of the 4. For every found object, compare its URI with the URI of the
manifest entry. manifest entry.
* For every object with non-matching URI issue a warning. This * For every object with a non-matching URI issue a warning.
case indicates that the object from the manifest entry is This case indicates that the object from the manifest entry is
found at a different location in a (possibly different) (also) found at a different location in a (possibly different)
repository. repository.
* If no objects with matching URI found, issue a warning. This * If no objects with a matching URI are found, issue a warning.
case indicates that there is no object found in the repository This case indicates that there is no object found in the
at the location listed in the manifest entry (but there is at repository at the location listed in the manifest entry (but
least one matching object found at a different location). there is at least one matching object found at a different
location).
5. Use all found objects for further validation. 5. Use all found objects for further validation as per Section 3.2.
Please note that the above steps will not reject objects whose hash
matches the hash listed in the manifest, but the URI does not. The
warning is generated in this case. It indicates that there is an
inconsistency in a repository between the content of the publication
point and its manifest. The choice has been made in favour of the
manifest, because the manifest, and the object it refers to by the
hash are both RPKI signed objects, while the repository's directory
listing is not.
3.3. Object Store Cleanup 3.3. Object Store Cleanup
At the end of the TA tree validation the store cleanup is performed: At the end of every TA tree validation some objects are removed from
the store using the following steps:
1. Given all objects that were encountered during the current 1. Given all objects that were encountered during the current
validation run, remove from the store (Section 5.1.6) all objects validation run, remove from the store (Section 5.1.6) all objects
whose URI attribute matches the URI of one of the encountered whose URI attribute matches the URI of one of the encountered
objects, but the content's hash is different. This removes from objects, but the content's hash is different. This removes from
the store objects that were replaced in the repository by their the store objects that were replaced in the repository by their
newer versions at the same URIs. newer versions with the same URIs.
2. Remove from the store all objects that were last encountered 2. Remove from the store all objects that were last encountered
during validation long time ago (as specified by the local during validation a long time ago (as specified by the local
policy). This removes objects that do not appear on any valid policy). This removes objects that do not appear on any valid
manifest anymore (but possibly still published in a repository). manifest anymore (but possibly are still published in a
repository).
3. Remove from the store all objects that were downloaded recently 3. Remove from the store all objects that were downloaded recently
(as specified by the local policy), but have never been used in a (as specified by the local policy), but have never been used in
validation process. This removes objects that have never the validation process. This removes objects that have never
appeared on any valid manifest. appeared on any valid manifest.
Shortening the time interval used in step 2 will free disk space used Shortening the time interval used in step 2 will free disk space used
by the store, to the expense of downloading removed objects again if by the store, at the expense of downloading removed objects again if
they are still published in the repository. they are still published in the repository.
Extending the time interval used in step 3 will prevent repeated Extending the time interval used in step 3 will prevent repeated
downloads of repository objects, with the risk that such objects, if downloads of repository objects, with the risk that such objects, if
created massively by mistake or adversely, will fill up local disk created massively by mistake or by an adversary, will fill up local
space, if they are not cleaned up promptly. disk space, if they are not cleaned up promptly.
4. Remote Objects Fetcher 4. Remote Objects Fetcher
The fetcher is responsible for downloading objects from remote The fetcher is responsible for downloading objects from remote
repositories (described in Section 3 of [RFC6481]) using rsync repositories (described in Section 3 of [RFC6481]) using rsync
protocol ([rsync]), or RPKI Repository Delta Protocol (RRDP) protocol ([rsync]), or RPKI Repository Delta Protocol (RRDP)
([I-D.ietf-sidr-delta-protocol]). ([I-D.ietf-sidr-delta-protocol]).
4.1. Fetcher Operations 4.1. Fetcher Operations
For every successfully visited URI the fetcher keeps track of the For every visited URI the fetcher keeps track of the last time a
last time it happened. successful fetch occurred.
4.1.1. Fetch repository objects 4.1.1. Fetch repository objects
This operation receives one parameter - a URI. For rsync protocol This operation receives one parameter - a URI. For an rsync
this URI points to a directory in a remote repository. For RRDP repository this URI points to a directory. For an RRDP repository it
repository it points to the repository's notification file. points to the repository's notification file.
The fetcher performs following steps: The fetcher performs following steps:
1. If data associated with the URI has been downloaded recently (as 1. If data associated with the URI has been downloaded recently (as
specified by the local policy), skip following steps. specified by the local policy), skip following steps.
2. Download the remote objects using the URI provided (for an rsync 2. Download remote objects using the URI provided (for an rsync
repository use a recursive mode). repository use recursive mode).
3. For every new object that is downloaded, try to parse it as an 3. Perform syntactic verification of fetched objects. The type of
object of specific RPKI type (certificate, manifest, CRL, ROA, every object (certificate, manifest, CRL, ROA, or Ghostbusters
Ghostbusters record), based on the object's filename extension record), is determined based on the object's filename extension
(.cer, .mft, .crl, .roa, and .gbr, respectively), and perform (.cer, .mft, .crl, .roa, and .gbr, respectively). The syntax of
basic RPKI object validation (excluding resource certification the object is described in Section 4 of [RFC6487] for resource
path validation), as specified in [RFC6487] and [RFC6488]. certificates, step 1 of Section 3 of [RFC6488] for signed
objects, and specifically, Section 4 of [RFC6486] for manifests,
[RFC5280] for CRLs, Section 3 of [RFC6482] for ROAs, and
Section 5 of [RFC6493] for Ghostbusters records.
4. Put every downloaded valid object in the object store 4. Put every downloaded and syntactically correct object in the
(Section 5.1.1). object store (Section 5.1.1).
The time interval used in the step 1 should be chosen based on the The time interval used in the step 1 should be chosen based on the
acceptable delay in receiving repository updates. acceptable delay in receiving repository updates.
4.1.2. Fetch single repository object 4.1.2. Fetch single repository object
This operation receives one parameter - a URI that points to an This operation receives one parameter - a URI that points to an
object in a repository. object in a repository.
The fetcher performs following operations: The fetcher performs following operations:
1. If data associated with the URI has been downloaded recently (as 1. If data associated with the URI has been downloaded recently (as
specified by the local policy), skip all following steps. specified by the local policy), skip all following steps.
2. Download the remote object using the URI provided. 2. Download the remote object using the URI provided.
3. Try to parse the downloaded object as an object of a specific 3. Perform syntactic verification of fetched object. The type of
RPKI type (certificate, manifest, CRL, ROA, Ghostbusters record), object (certificate, manifest, CRL, ROA, or Ghostbusters record),
based on the object's filename extension (.cer, .mft, .crl, .roa, is determined based on the object's filename extension (.cer,
and .gbr, respectively), and perform basic RPKI object validation .mft, .crl, .roa, and .gbr, respectively). The syntax of the
(excluding resource certification path validation), as specified object is described in Section 4 of [RFC6487] for resource
in [RFC6487] and [RFC6488]. certificates, step 1 of Section 3 of [RFC6488] for signed
objects, and specifically, Section 4 of [RFC6486] for manifests,
[RFC5280] for CRLs, Section 3 of [RFC6482] for ROAs, and
Section 5 of [RFC6493] for Ghostbusters records.
4. If the downloaded object is not valid, issue an error and skip 4. If the downloaded object is not syntactically correct, issue an
further steps. error and skip further steps.
5. Delete all objects from the object store (Section 5.1.5) whose 5. Delete all objects from the object store (Section 5.1.5) whose
URI matches the URI given. URI matches the URI given.
6. Put the validated object in the object store (Section 5.1.1). 6. Put the downloaded object in the object store (Section 5.1.1).
5. Local Object Store 5. Local Object Store
5.1. Store Operations 5.1. Store Operations
5.1.1. Store Repository Object 5.1.1. Store Repository Object
Put given object in the store, along with its type, URI, hash, and Put given object in the store, along with its type, URI, hash, and
AKI, if there is no record with the same hash and URI fields. AKI, if there is no record with the same hash and URI fields. Note
that in the (unlikely) event of hash collision the given object will
not replace the object in the store.
5.1.2. Get objects by hash 5.1.2. Get objects by hash
Retrieve all objects from the store whose hash attribute matches the Retrieve all objects from the store whose hash attribute matches the
given hash. given hash.
5.1.3. Get certificate objects by URI 5.1.3. Get certificate objects by URI
Retrieve from the store all objects of type certificate, whose URI Retrieve from the store all objects of type certificate, whose URI
attribute matches the given URI. attribute matches the given URI.
skipping to change at page 10, line 36 skipping to change at page 11, line 15
5.1.7. Update object's validation time 5.1.7. Update object's validation time
For all objects in the store whose hash attribute matches the given For all objects in the store whose hash attribute matches the given
hash, set the last validation time attribute to the given timestamp. hash, set the last validation time attribute to the given timestamp.
6. Acknowledgements 6. Acknowledgements
This document describes the algorithm as it is implemented by the This document describes the algorithm as it is implemented by the
software development team at the RIPE NCC. The authors would also software development team at the RIPE NCC. The authors would also
like to acknowledge contributions by Carlos Martinez, Andy Newton, like to acknowledge contributions by Carlos Martinez, Andy Newton,
and Rob Austein. Rob Austein, and Stephen Kent.
7. IANA Considerations 7. IANA Considerations
This document has no actions for IANA. This document has no actions for IANA.
8. Security Considerations 8. Security Considerations
This implementation will not detect possible hash collisions in the This implementation will not detect possible hash collisions in the
hashes of repository objects (calculated using the file hash hashes of repository objects (calculated using the file hash
algorithm specified in [RFC6485]), and considers objects with same algorithm specified in [RFC6485]). It considers objects with same
hash values as identical. hash values as identical.
This algorithm uses the content of a manifest object to discover This algorithm uses the content of a manifest object to discover
other objects issued by a specified CA. It verifies that the other objects issued by a specified CA. It verifies that the
manifest is located in the publication point designated in the CA manifest is located in the publication point designated in the CA
Certificate. However, if there are other (not listed in the Certificate. However, if there are other (not listed in the
manifest) objects located in that publication point directory, they manifest) objects located in that publication point directory, they
will be ignored, even if their content is correct and they are issued will be ignored, even if their content is correct and they are issued
by the same CA as the manifest. by the same CA as the manifest. (This behavior is allowed, but not
required, by [RFC6486].)
In contrast, objects whose content hash matches the hash listed in In contrast, objects whose content hash matches the hash listed in
the manifest, but that are not located in the publication directory the manifest, but that are not located in the publication directory
listed in their CA certificate, will be used in the validation listed in their CA certificate, will be used in the validation
process (although a warning will be issued in that case). process (although a warning will be issued in that case), as
explained in Section 3.2.2.
The store cleanup procedure described in Section 3.3 tries to The store cleanup procedure described in Section 3.3 tries to
minimise removal and subsequent re-fetch of objects that are minimise removal and subsequent re-fetch of objects that are
published in a repository but not used in the validation. Once such published in a repository, but not used in the validation. Once such
objects are removed from the remote repository, they will be objects are removed from the remote repository, they will be
discarded from the local object store after a period of time discarded from the local object store after a period of time
specified by a local policy. By generating an excessive amount of specified by a local policy. By generating an excessive amount of
syntactically valid RPKI objects, a man-in-the-middle attack between syntactically valid RPKI objects, a man-in-the-middle attack between
a validating tool and a repository could force an implementation to a validating tool and a repository could force an implementation to
fetch and store those objects in the object store before they are fetch and store those objects in the object store before they are
validated and discarded, leading to an out-of-memory or out-of-disk- validated and discarded, leading to an out-of-memory or out-of-disk-
space conditions, and, subsequently, a denial of service. space conditions, and, subsequently, a denial of service.
9. References 9. References
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