Keith Welter writes:
> In this case, the INVALID_SYNTAX could relate to the SA, TSi or TSr 
> payload in the 
> IKE_AUTH response which would would mean that creation of the CHILD SA 
> failed, 
> not the IKE SA.  I think INVALID_SYNTAX is ambiguous here without an 
> explicit delete 
> payload for either the IKE SA or the CHILD SA.

For normal errors in the SA payload there is NO_PROPOSAL_CHOSEN error
and for TSi and TSr there is TS_UNACCEPTABLE error.

If INVALID_SYNTAX is generated from for example SA payload because the
payload lengths inside the SA / Proposal / Transform payload
substructure is wrong (or there is other payload type inside SA
payload than what is allowed) then that again means the one end is
broken and there is no point of continuing creating the IKE SA as most
likely all future exchanges will fail in similar way.

It is clear for me that if INVALID_SYNTAX is ever returned to IKE_AUTH
exchange, that means the IKE SA was not successfully created (as we
do now know whether the other end for example verified the AUTH
payload). In that case when IKE SA was not created there is no IKE SA
to send delete payload to.

If INVALID_SYNTAX is returned after that as response to INFORMATIONAL
or CREATE_CHILD exchange, then it is not clear whether other deleted
the SA or not, but as I said earlier that can only happen if there is
bugs in implementations, so better to cut the discussion short to
limit attack options. 
-- 
kivi...@iki.fi
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