[Anima] Roman Danyliw's Discuss on draft-ietf-anima-autonomic-control-plane-27: (with DISCUSS and COMMENT)

Roman Danyliw via Datatracker <noreply@ietf.org> Wed, 15 July 2020 03:03 UTC

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Subject: [Anima] Roman Danyliw's Discuss on draft-ietf-anima-autonomic-control-plane-27: (with DISCUSS and COMMENT)
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Roman Danyliw has entered the following ballot position for
draft-ietf-anima-autonomic-control-plane-27: Discuss

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----------------------------------------------------------------------
DISCUSS:
----------------------------------------------------------------------

** As normative behavior is specific for BRSKI (e.g., Section 6.1.5 and
6.1.5.5), please make it a normative reference

** Figure 2’s definition of acp-address is ‘acp-address = 32HEXLC | "0"’.  The
following text references a 32HEXDIG but that isn’t in the definition of
acp-address.

-- Section 6.1.2.  ‘Nodes complying with this specification MUST be able to
receive their ACP address through the domain certificate, in which case their
own ACP domain certificate MUST have the 32HEXDIG "acp-address" field.’

-- Section 6.1.3.  ‘The candidate peer certificate's acp-node-name has a
non-empty acp-address field (either 32HEXDIG or 0, according to Figure 2).’

** Precision in bounding the cipher selection.

-- Section 6.7.2.  Per “Symmetric encryption for the transmission of secure
channel data MUST use encryption schemes considered to be security wise equal
to or better than AES256”, which property of AES-256 is being considered for
this assessment?

-- Section 6.8.2.  Per “TLS for GRASP MUST offer
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 and
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 and MUST NOT offer options with less
than 256bit AES or less than SHA384”, please state this more precisely.

-- Is it that AES-128 shouldn’t be used or that that AES-256 has a certain key
strength to which to adhere to?

-- Is it that SHA-224 or SHA256 shouldn’t be used (staying in the SHA-2 family)
or is it a certain number of bits of security ?

** The text specifies the need for physical controls.  Please be more specific
on the appropriate degree of that physical control or how that decision should
be made; and explicitly explain threat of concern.

-- Section 8.1.1.  “Thus, the ACP connect interface and NOC systems connected
to it needs to be physically controlled/secured.”

-- Section 8.1.5.  “… the ACP connect link and the nodes connecting to it must
be in a contiguous secure   environment, hence assuming there can be no
physical attack against the devices.”

** (“discuss discuss”) Section 8.1.2.  What is the normative behavior being
specified in this section?  Specifically, what is the additional or more
restrictive behavior for the circumstance is where an ACP node is virtualized.

** Section 8.2.1.  (I’m no ABNF expert …) Per the ABNF in Figure 17, the “//=”
notation isn’t valid.  I think you want:

OLD
     method //= [ "DTLS",    port ]

NEW
     method =/ [ "DTLS",    port ]

** Section 10.2.1.  Per “An attacker will not be able to join the ACP unless
having a valid domain certificate, also packet injection and sniffing traffic
will not be possible due to the security provided by the encryption protocol.”,
please be clearer:

-- on path attacker = no packet injection
-- on path attacker = only traffic analysis when sniffing
-- compromised node = can inject traffic

** Section 11.  Per “an ACP is self-protecting and there is no need to apply
configuration to make it secure”, if this assertion is going to be made:

-- please specify the security services/properties in a normative section (not
in the informative text in Section 10).

-- please also be clear on what configuration is being referenced.

** Section 11.  Per the list of factors on which ACP depends, it seems like the
following are missing:

-- the security properties of the enrollment protocol

-- that the security considerations of EST and BRSKI apply (or if not, why not)


----------------------------------------------------------------------
COMMENT:
----------------------------------------------------------------------

(Preliminary ballot.  Need to double check that all of ekr's discusses were
cleared)

The style of explaining the design choice after describing an element of the
protocol was informative and helpful.  Thanks.

The this document has undergone a significant amount of security review.  Thank
you for incorporating all of this feedback.

** Section 6.  It doesn’t seem appropriate to call a protocol “indestructible”
unless you are going to enumerate the resiliency properties more precisely –
“many inadvertent changes” is vague.

** Section 6.  Per “An ACP node can be … or any other IP a capable node”,
should this be “IPv6 capable node”?

** Section 6.1.1.  Per “… it is beneficial to copy the device identifying
fields of the node's IDevID certificate into the ACP domain certificate …”, is
there a ACP-recommended approach for that?

** Section 6.1.3.1. Per “In the absence of implementing a secured mechanism,
such an ACP node MAY use a current time learned in an insecured fashion in the
ACP domain membership check.”, please be clearer on how this current time is
learned in the domain membership check.

** Section 6.1.5.  Per “ACP nodes SHOULD be able to remember the IPv6 locator
parameters ...”, what happens if they don’t remember?

** Section 6.1.5.3.  Per “The connecting ACP node SHOULD verify that the CRLDP
certificate used during the HTTPs connection has the same ACP address as
indicated in the CRLDP URL …”, why is this not a MUST?

** Section 6.1.5.5.  Per “An ACP node may determine that its ACP domain
certificate has expired … [i]n this case, the ACP node SHOULD convert to a role
of a re-enrolling candidate ACP node”, what is the alternative if it wants to
connect back to the network?  Shouldn’t this be a MUST?

** Section 6.5.  It seems misplaced to describe MacSec as an option for channel
security even when it is not a profiled in this document.

** Section 6.7.2. Per “Signaling of TA certificates may not be appropriate when
the deployment is relying on a security model when the TA certificate content
is considered confidential”, where is the requirement to signal TA certificates
discussed.  How would this selection of signaling a TA work?  The entire
paragraph prior seemed to explicitly discuss that the TA doesn’t need to be
shared.

** Section 6.7.2.  Per “When introducing the profile for security association
protocol …”, I recommend being clearer to whom you are providing this advice. 
This seems to for operators of ACP infrastructure technology (not
implementers/vendors of ACP technology)

** Section 6.7.3.  Per “The ACP usage of IPsec and IKEv2 mandates a profile
with a narrow set of options of the current standards-track usage guidance for
IPsec    [RFC8221] and IKEv2 [RFC8247]”, should there be normative wording use
(MUST) instead of a “mandates”?

** Section 6.7.3.1.1.  Per ENCR_CHACHA20_POLY1305, “[t]herefore this algorithm
is only recommended”, shouldn’t it read as RECOMMENDED?

** Section 6.7.3.1.2.  Per “[RFC8247] provides a baseline recommendation for
mandatory to   implement ciphers, integrity checks, pseudo-random-functions and
Diffie-Hellman mechanisms.  Those recommendations, and the recommendations of
subsequent documents apply well to the ACP.”, it seems like normative language
should be used to adhered to.

** Section 6.10.7.3.  The paragraph/sentence starting with “ACP registrars that
are aware of can use …” doesn’t parse.  The guidance isn’t clear as a result.

** Section 6.10.7.3.  Per “In a simple allocation scheme, an ACP registrar
remembers persistently across reboots …”, what’s the recover step if it loses
that state?

** Section 6.11.1.1.2.  Not clear what “DODAG Information Objects (DIOs) SHOULD
be sent 2 .. 3 times” means – can “2 .. 3” please be clarified.

** Section 6.11.1.1.2.  A mechanism for failed ACP detected using a secure
channel protocol is noted for IPSec (with IKEv2 Dead Peer Detection).  What is
the equivalent for DTLS?

** Section 9.  The section notes that Section 9.1 is “derived from diagnostic
of a commercially available ACP implementation”.  The shepherd report from
03/2019 notes that there are no implementations of ACP.  If this is documented
somewhere, it would be very compelling to cite it.

** Section 9.1. Per “The basic diagnostics [sic] is support of (yang) data
models representing the complete (auto-)configuration and operational state of
all components …”, are these YANG models defined?  Are there references?

** Section 9.3.1.  Per “Whenever this document refers to enabling an interface
for ACP … it only requires to permit [sic] the interface …”, this seems like
normative behavior in an informative section.

** Section 9.3.2.  That this is an information section is noted.  It would
benefit from describing what precisely can and cannot be done in the three
states proposed – up, down and admin down.

** Section 9.3.2.1.  What is the proposed threat that using admin down is
intended to mitigate?  Under what circumstance should it be invoked?

** Section 9.3.2.1.  Per ‘"Admin down" state as described above provides also a
high level of security because it only permits ACP/ANI operations which are
both well secured”, to what is the “both” referring? I suspect this is
editorial (but just in case, noting here).

** Section 10.2.2.  Per “For example, management plane functions (transport
ports) should only be reachable from the ACP but not the Data-Plane”, this
seems like good guidance.  Is there a reason not to upgrade this informative
statement and put it the Security Considerations as normative guidance?

** Section 10.2.2.  Per “Protection across all potential attack vectors is
typically easier to do in devices whose software is designed from the ground up
with security in mind than with legacy software based systems where the ACP is
added on as another feature”, no argument on the general principle.  However,
as it relates to ACP:

--what’s an example of the legacy software?

-- as noted in the shepherd report from 03/2019, there are no implementations,
so is there reason to believe that this is going to put on “legacy” platforms?

** Section 10.2.2.  Per “As explained above, traffic across the ACP SHOULD
still …”, is RFC2119 language really intended in this informative section?

** Section 11.  Per “Security can be compromised by implementation errors
(bugs), as in all products”, given the generic nature of this statement,
couldn’t it also be a configuration error in the product too?

** Section 11.  Per “Higher layer service built using ACP domain certificates
should not rely on undifferentiated group security …” is there a reason not to
make this a normative SHOULD?

** Editorial

-- Recommend being consistent on either “ACP domain certificates” or “ACP
certificates”

-- Section 1.  Editorially.  The two sentences “Section 7 defines normative how
to …” and “Section 8 explain normative how …” don’t parse as the adjective
normative needs a noun to modify.

-- Section 6.1.4.  Editorial.  s/These requirements can be achieved by using TA
private/These requirements can be achieved by using a TA private/

-- Section 6.2.  Editorial. s/does intentionally not/intentionally does not/

-- Section 6.5.  Editorial.  Per “Note that MacSec is not required by any
profiles of the ACP in this specification but just mentioned as a likely next
interesting secure channel protocol.”, does not parse.

-- Section 6.10.7.  Per “ACP registrars are responsible to enroll candidate ACP
nodes with ACP domain certificates and associated trust point(s)”, is a trust
point the same thing as a trust anchor?    If so, I recommend being consistent.
 If not, then please define it.

-- Section 6.11.1.  Please make draft-ietf-roll-applicability-template a
reference.

-- Section 6.11.1.5.  Editorially.  It might be worth framing the path metric
in the form of sentence.

-- Section 11. s/enemy plegdes/rogue pledges/

-- Section 11. Per “Fundamentally, security depends on avoid operator and
network automation mistakes …”, this paragraph is not actionable.  Recommend
removal.

** Typos
Section 1.  Typo. s/parth/path/
Section 1.  Typo. s/seperately/separately/
Section 1.  Typo. s/automaticically/ automatically/
Section 1.  Typo. s/managemenet/ management/
Section 1.  Typo. s/absene/absence/
Section 1.1.  Typo. s/solution:/solution/
Section 2.  Typo. s/netork/network/
Section 2.  Typo. s/physcially/physically/
Section 5.  Typo. s/(see (see/(see/
Section 5. Typo. s/loopack/loopback/
Section 6.1.1.  Typo. s/e.g.:signing/e.g., signing/
Section 6.1.1.  Typo. s/signalled/signaled/g
Section 6.1.1.  Typo. s/bei/by/
Section 6.1.2.  Typo. s/simpy/simply/
Section 6.1.2.  Typo. s/readible/readable/
Section 6.1.2.  Typo. s/Adresses/Addresses/
Section 6.1.2.  Typo. s/manadatory/mandatory/
Section 6.1.2. Typo. s/inapproprite/inappropriate/
Section 6.1.3.1.  Typo. s/as as/as/
Section 6.1.3.1.  Typo. /insecured/insecure/
Section 6.1.3.1.  Typo. s/likley/likely/
Section 6.2. Typo. s/IKEv2 has am/IKEv2 has an/
Section 6.7.2.  Typo. s/successfull/successful/
Section 6.7.3.1.1.  Typo.  s/superceed/superseded/
(I stopped documenting spelling errors at Section 6.7.3.1.1.  Please run a
spell checker before handing this off to the RFC Editor)