Migrating from 'auto-dnssec maintain;' to dnssec-policy did not
work properly, mainly because the legacy keys were initialized
badly. Earlier commit deals with migration where existing keys
match the policy. This commit deals with migration where existing
keys do not match the policy. In that case, named must not
immediately delete the existing keys, but gracefully roll to the
dnssec-policy.
However, named did remove the existing keys immediately. This is
because the legacy key states were initialized badly. Because
those keys had their states initialized to HIDDEN or RUMOURED, the
keymgr decides that they can be removed (because only when the key
has its states in OMNIPRESENT it can be used safely).
The original thought to initialize key states to HIDDEN (and
RUMOURED to deal with existing keys) was to ensure that those keys
will go through the required propagation time before the keymgr
decides they can be used safely. However, those keys are already
in the zone for a long time and making the key states represent
otherwise is dangerous: keys may be pulled out of the zone while
in fact they are required to establish the chain of trust.
Fix initializing key states for existing keys by looking more closely
at the time metadata. Add TTL and propagation delays to the time
metadata and see if the DNSSEC records have been propagated.
Initialize the state to OMNIPRESENT if so, otherwise initialize to
RUMOURED. If the time metadata is in the future, or does not exist,
keep initializing the state to HIDDEN.
The added test makes sure that new keys matching the policy are
introduced, but existing keys are kept in the zone until the new
keys have been propagated.
Migrating from 'auto-dnssec maintain;' to dnssec-policy did not
work properly, mainly because the legacy keys were initialized
badly. Several adjustments in the keymgr are required to get it right:
- Set published time on keys when we calculate prepublication time.
This is not strictly necessary, but it is weird to have an active
key without the published time set.
- Initalize key states also before matching keys. Determine the
target state by looking at existing time metadata: If the time
data is set and is in the past, it is a hint that the key and
its corresponding records have been published in the zone already,
and the state is initialized to RUMOURED. Otherwise, initialize it
as HIDDEN. This fixes migration to dnssec-policy from existing
keys.
- Initialize key goal on keys that match key policy to OMNIPRESENT.
These may be existing legacy keys that are being migrated.
- A key that has its goal to OMNIPRESENT *or* an active key can
match a kasp key. The code was changed with CHANGE 5354 that
was a bugfix to prevent creating new KSK keys for zones in the
initial stage of signing. However, this caused problems for
restarts when rollovers are in progress, because an outroducing
key can still be an active key.
The test for this introduces a new KEY property 'legacy'. This is
used to skip tests related to .state files.
Algorithm rollover waited too long before introducing zone
signatures. It waited to make sure all signatures were resigned,
but when introducing a new algorithm, all signatures are resigned
immediately. Only add the sign delay if there is a predecessor key.
Algorithm rollover was stuck on submitting DS because keymgr thought
it would move to an invalid state. It did not match the current
key because it checked it against the current key in the next state.
Fixed by when checking the current key, check it against the desired
state, not the existing state.
When you do a restart or reconfig of named, or rndc loadkeys, this
triggers the key manager to run. The key manager will check if new
keys need to be created. If there is an active key, and key rollover
is scheduled far enough away, no new key needs to be created.
However, there was a bug that when you just start to sign your zone,
it takes a while before the KSK becomes an active key. An active KSK
has its DS submitted or published, but before the key manager allows
that, the DNSKEY needs to be omnipresent. If you restart named
or rndc loadkeys in quick succession when you just started to sign
your zone, new keys will be created because the KSK is not yet
considered active.
Fix is to check for introducing as well as active keys. These keys
all have in common that their goal is to become omnipresent.
Add a key manager to named. If a 'dnssec-policy' is set, 'named'
will run a key manager on the matching keys. This will do a couple
of things:
1. Create keys when needed (in case of rollover for example)
according to the set policy.
2. Retire keys that are in excess of the policy.
3. Maintain key states according to "Flexible and Robust Key
Rollover" [1]. After key manager ran, key files will be saved to
disk.
[1] https://matthijsmekking.nl/static/pdf/satin2012-Schaeffer.pdf
KEY GENERATION
Create keys according to DNSSEC policy. Zones configured with
'dnssec-policy' will allow 'named' to create DNSSEC keys (similar
to dnssec-keymgr) if not available.
KEY ROLLOVER
Rather than determining the desired state from timing metadata,
add a key state goal. Any keys that are created or picked from the
key ring and selected to be a successor has its key state goal set
to OMNIPRESENT (this key wants to be signing!). At the same time,
a key that is being retired has its key state goal set to HIDDEN.
The keymgr state machine with the three rules will make sure no
introduction or withdrawal of DNSSEC records happens too soon.
KEY TIMINGS
All timings are based on RFC 7583.
The keymgr will return when the next action is happening so
that the zone can set the proper rekey event. Prior to this change
the rekey event will run every hour by default (configurable),
but with kasp we can determine exactly when we need to run again.
The prepublication time is derived from policy.
