Benjamin Kaduk's Discuss on draft-ietf-bfd-yang-16: (with DISCUSS and COMMENT)

[Benjamin Kaduk <[e-mail]>]

Benjamin Kaduk has entered the following ballot position for
draft-ietf-bfd-yang-16: Discuss

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DISCUSS:
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Section 2.1 describes a scheme wherein an IGP may generate events that
cause BFD sessions to be created/destroyed; this effectively is proxying
commands from IGP over the local BFD API, which brings the authentication
and authorization of the IGP into scope, even if the local BFD
configuration access is authenticated.  (That is, the proxying component is
always authenticated, but now bears responsibility for performing
authentication/authorization/sanity checks on commands before proxying
them.)  Since IGP security is a topic for elsewhere, the changes to this
document seem scoped to documenting the requirements on the IGP/local proxy
for these checks, and arguably for only allowing authenticated IGP events
to create authenticated BFD sessions (though arguably not as well, for the
latter, since this is a YANG model document and not an architecture
document).


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COMMENT:
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I'm not very familiar with YANG notifications; is there a risk that they
can be abused as a DoS attack vector on the notification recipient by an
attacker (e.g., by causing a flapping series of state transition events or
by creating/destroying many sessions)?

Regarding the Security Considerations:

It's unclear whether local-multiplier, the various intervals, and
authentication are the only nodes that merit mention for every
per-forwarding-path-type module.  For example, source/destination addresses
could be modified to direct traffic at unwitting recipients, and the
key-chain and meticulous settings also seem security-related.

Similarly, read-only access to the discriminators (and
key-chain/authentication information) could make it easier for an attacker
to spoof traffic.