There are a couple of cases where the safety intervals are added
inappropriately:
1. When setting the PublishCDS/SyncPublish timing metadata, we don't
need to add the publish-safety value if we are calculating the time
when the zone is completely signed for the first time. This value
is for when the DNSKEY has been published and we add a safety
interval before considering the DNSKEY omnipresent.
2. The retire-safety value should only be added to ZSK rollovers if
there is an actual rollover happening, similar to adding the sign
delay.
3. The retire-safety value should only be added to KSK rollovers if
there is an actual rollover happening. We consider the new DS
omnipresent a bit later, so that we are forced to keep the old DS
a bit longer.
While converting the kasp system test to pytest, I encountered a small
bug in the keymgr code. We retire keys when there is more than one
key matching a 'keys' line from the dnssec-policy. But if there are
multiple identical 'keys' lines, as is the case for the test zone
'checkds-doubleksk.kasp', we retire one of the two keys that have the
same properties.
Fix this by checking if there are double matches. This is not fool proof
because there may be many keys for a few identical 'keys' lines, but it
is good enough for now. In practice it makes no sense to have a policy
that dictates multiple keys with identical properties.
Add an option to dnssec-ksr keygen, -o, to create KSKs instead of ZSKs.
This way, we can create a set of KSKS for a given period too.
For KSKs we also need to set timing metadata, including "SyncPublish"
and "SyncDelete". This functionality already exists in keymgr.c so
let's make the function accessible.
Replace dnssec-keygen calls with dnssec-ksr keygen for KSK in the
ksr system test and check keys for created KSKs as well. This requires
a slight modification of the check_keys function to take into account
KSK timings and metadata.
If the ZSK has lifetime unlimited, the timing metadata "Inactive" and
"Delete" cannot be found and is treated as an error. Fix by allowing
these metadata to not exist.
If there is an algorithm rollover and two keys of different algorithm
share the same keytags, then there is a possibility that if we check
that a key matches a specific state, we are checking against the wrong
key.
Fix this by not only checking for matching key id but also key
algorithm.
With offline-ksk enabled, we don't run the keymgr because the key
timings are determined by the SKR. We do update the key states but
we derive them from the timing metadata.
Then, we can skip a other tasks in offline-ksk mode, like DS checking
at the parent and CDS synchronization, because the CDS and CDNSKEY
RRsets also come from the SKR.
Remove the complicated mechanism that could be (in theory) used by
external libraries to register new categories and modules with
statically defined lists in <isc/log.h>. This is similar to what we
have done for <isc/result.h> result codes. All the libraries are now
internal to BIND 9, so we don't need to provide a mechanism to register
extra categories and modules.
The key lifetime should no longer be adjusted if the key is being
retired earlier, for example because a manual rollover was started.
This would falsely be seen as a dnssec-policy lifetime reconfiguration,
and would adjust the retire/removed time again.
This also means we should update the status output, and the next
rollover scheduled is now calculated using (retire-active) instead of
key lifetime.
If dnssec-policy is reconfigured and the key lifetime has changed,
update existing keys with the new lifetime and adjust the retire
and removed timing metadata accordingly.
If the key has no lifetime yet, just initialize the lifetime. It
may be that the retire/removed timing metadata has already been set.
Skip keys which goal is not set to omnipresent. These keys are already
in the progress of retiring, or still unused.
The Depends relation refers to types of rollovers in which a certain
record type is going to be swapped. Specifically, the Depends relation
says there should be no dependency on the predecessor key (the set
Dep(x, T) must be empty).
But if the key is phased out (all its states are in HIDDEN), there is
no longer a dependency. Since the relationship is still maintained
(Predecessor and Successor metadata), the keymgr_dep function still
returned true. In other words, the set Dep(x, T) is not considered
empty.
This slows down key rollovers, only retiring keys when the successor
key has been fully propagated.
Add a default key-directory parameter to the function that can
be returned if there is no keystore, or if the keystore directory
is NULL (the latter is also true for the built-in keystore).
When using the same PKCS#11 URI for a zone that uses different
DNSSEC policies, the PKCS#11 label could collide, i.e. the same
label could be used for different keys. Add the policy name to
the label to make it more unique.
Also, the zone name could contain characters that are interpreted
as special characters when parsing the PKCS#11 URI string. Mangle
the zone name through 'dns_name_tofilenametext()' to make it
PKCS#11 safe.
Move the creation to a separate function for clarity.
Furthermore, add a log message whenever a PKCS#11 object has been
successfully created.
The internal keymgr used 'isc_dir_open(&dir)' and 'isc_dir_close(&dir)',
but was not using the variable 'dir`, other than checking if the
directory can be opened. Errors like these will be be caught already
in the dst_api function calls.
When writing key files to disk, use the internally stored directory.
Add an access function 'dst_key_directory()'.
Most calls to keymgr functions no longer need to provide the
key-directory value. Only 'dns_keymgr_run' still needs access to
the zone's key-directory in case the key-store is set to the built-in
key-directory.
If there is a keystore configured with a PKCS#11 URI, zones that
are using a dnssec-policy that uses such a keystore should create keys
via the PKCS#11 interface. Those keys are generally stored inside an
HSM.
Some changes to the code are required, to store the engine reference
into the keystore.
Allow larger TTL values in zones that go insecure. This is necessary
because otherwise the zone will not be loaded due to the max-zone-ttl
of P1D that is part of the current insecure policy.
In the keymgr.c code, default back to P1D if the max-zone-ttl is set
to zero.
Set the DS state after issuing 'rndc dnssec -checkds'. If the DS
was published, it should go in RUMOURED state, regardless whether it
is already safe to do so according to the state machine.
Leaving it in HIDDEN (or if it was magically already in OMNIPRESENT or
UNRETENTIVE) would allow for easy shoot in the foot situations.
Similar, if the DS was withdrawn, the state should be set to
UNRETENTIVE. Leaving it in OMNIPRESENT (or RUMOURED/HIDDEN)
would also allow for easy shoot in the foot situations.
Add a new parameter to the dst_key structure, mark a key modified if
dst_key_(un)set[bool,num,state,time] is called. Only write out key
files during a keymgr run if the metadata has changed.
Previously, the unreachable code paths would have to be tagged with:
INSIST(0);
ISC_UNREACHABLE();
There was also older parts of the code that used comment annotation:
/* NOTREACHED */
Unify the handling of unreachable code paths to just use:
UNREACHABLE();
The UNREACHABLE() macro now asserts when reached and also uses
__builtin_unreachable(); when such builtin is available in the compiler.
This commit converts the license handling to adhere to the REUSE
specification. It specifically:
1. Adds used licnses to LICENSES/ directory
2. Add "isc" template for adding the copyright boilerplate
3. Changes all source files to include copyright and SPDX license
header, this includes all the C sources, documentation, zone files,
configuration files. There are notes in the doc/dev/copyrights file
on how to add correct headers to the new files.
4. Handle the rest that can't be modified via .reuse/dep5 file. The
binary (or otherwise unmodifiable) files could have license places
next to them in <foo>.license file, but this would lead to cluttered
repository and most of the files handled in the .reuse/dep5 file are
system test files.
Remove the dynamic registration of result codes. Convert isc_result_t
from unsigned + #defines into 32-bit enum type in grand unified
<isc/result.h> header. Keep the existing values of the result codes
even at the expense of the description and identifier tables being
unnecessary large.
Additionally, add couple of:
switch (result) {
[...]
default:
break;
}
statements where compiler now complains about missing enum values in the
switch statement.
When checking the current DNSSEC state against the policy, consider
offline keys. If we didn't found an active key, check if the key is
offline by checking the public key list. If there is a match in the
public key list (the key data is retrieved from the .key and the
.state files), treat the key as offline and don't create a successor
key for it.
When the keymgr needs to create new keys, it is possible it needs to
create multiple keys. The keymgr checks for keyid conflicts with
already existing keys, but it should also check against that it just
created.
The 'keymgr_key_init()' function initializes key states if they have
not been set previously. It looks at the key timing metadata and
determines using the given times whether a state should be set to
RUMOURED or OMNIPRESENT.
However, the DNSKEY and ZRRSIG states were mixed up: When looking
at the Activate timing metadata we should set the ZRRSIG state, and
when looking at the Published timing metadata we should set the
DNSKEY state.
On each keymgr run, we now also check if key files can be removed.
The 'purge-keys' interval determines how long keys should be retained
after they have become completely hidden.
Key files should not be removed if it has a state that is set to
something else then HIDDEN, if purge-keys is 0 (disabled), if
the key goal is set to OMNIPRESENT, or if the key is unused (a key is
unused if no timing metadata set, and no states are set or if set,
they are set to HIDDEN).
If the last changed timing metadata plus the purge-keys interval is
in the past, the key files may be removed.
Add a dst_key_t variable 'purge' to signal that the key file should
not be written to file again.
Three small cleanups:
1. Remove an unused keystr/dst_key_format.
2. Initialize a dst_key_state_t state with NA.
3. Update false comment about local policy (local policy only adds
barrier on transitions to the RUMOURED state, not the UNRETENTIVE
state).
There was a bug in function 'keymgr_ds_hidden_or_chained()'.
The funcion 'keymgr_ds_hidden_or_chained()' implements (3e) of rule2
as defined in the "Flexible and Robust Key Rollover" paper. The rules
says: All DS records need to be in the HIDDEN state, or if it is not
there must be a key with its DNSKEY and KRRSIG in OMNIPRESENT, and
its DS in the same state as the key in question. In human langauge,
if all keys have their DS in HIDDEN state you can do what you want,
but if a DS record is available to some validators, there must be
a chain of trust for it.
Note that the barriers on transitions first check if the current
state is valid, and then if the next state is valid too. But
here we falsely updated the 'dnskey_omnipresent' (now 'dnskey_chained')
with the next state. The next state applies to 'key' not to the state
to be checked. Updating the state here leads to (true) always, because
the key that will move its state will match the falsely updated
expected state. This could lead to the assumption that Key 2 would be
a valid chain of trust for Key 1, while clearly the presence of any
DS is uncertain.
The fix here is to check if the DNSKEY and KRRSIG are in OMNIPRESENT
state for the key that does not have its DS in the HIDDEN state, and
only if that is not the case, ensure that there is a key with the same
algorithm, that provides a valid chain of trust, that is, has its
DNSKEY, KRRSIG, and DS in OMNIPRESENT state.
The changes in 'keymgr_dnskey_hidden_or_chained()' are only cosmetical,
renaming 'rrsig_omnipresent' to 'rrsig_chained' and removing the
redundant initialization of the DST_KEY_DNSKEY expected state to NA.
The previous commit changed the function definition of
'keymgr_key_is_successor()', this commit updates the code where
this function is called.
In 'keymgr_key_exists_with_state()' the logic is also updated slightly
to become more readable. First handle the easy cases:
- If the key does not match the state, continue with the next key.
- If we found a key with matching state, and there is no need to
check the successor relationship, return (true).
- Otherwise check the successor relationship.
In 'keymgr_key_has_successor()' it is enough to check if a key has
a direct successor, so instead of calling 'keymgr_key_is_successor()',
we can just check 'keymgr_direct_dep()'.
In 'dns_keymgr_run()', we want to make sure that there is no
dependency on the keys before retiring excess keys, so replace
'keymgr_key_is_successor()' with 'keymgr_dep()'.
So far the key manager could only deal with two keys in a rollover,
because it used a simplified version of the successor relationship
equation from "Flexible and Robust Key Rollover" paper. The simplified
version assumes only two keys take part in the key rollover and it
for that it is enough to check the direct relationship between two
keys (is key x the direct predecessor of key z and is key z the direct
successor of key x?).
But when a third key (or more keys) comes into the equation, the key
manager would assume that one key (or more) is redundant and removed
it from the zone prematurely.
Fix by implementing Equation(2) correctly, where we check for
dependencies on keys:
z ->T x: Dep(x, T) = ∅ ∧
(x ∈ Dep(z, T) ∨
∃ y ∈ Dep(z, T)(y != z ∧ y ->T x ∧ DyKyRySy = DzKzRzSz))
This says: key z is a successor of key x if:
- key x depends on key z if z is a direct successor of x,
- or if there is another key y that depends on key z that has identical
key states as key z and key y is a successor of key x.
- Also, key x may not have any other keys depending on it.
This is still a simplified version of Equation(2) (but at least much
better), because the paper allows for a set of keys to depend on a
key. This is defined as the set Dep(x, T). Keys in the set Dep(x, T)
have a dependency on key x for record type T. The BIND implementation
can only have one key in the set Dep(x, T). The function
'keymgr_dep()' stores this key in 'uint32_t *dep' if there is a
dependency.
There are two scenarios where multiple keys can depend on a single key:
1. Rolling keys is faster than the time required to finish the
rollover procedure. This scenario is covered by the recursive
implementation, and checking for a chain of direct dependencies
will suffice.
2. Changing the policy, when a zone is requested to be signed with
a different key length for example. BIND 9 will not mark successor
relationships in this case, but tries to move towards the new
policy. Since there is no successor relationship, the rules are
even more strict, and the DNSSEC reconfiguration is actually slower
than required.
Note: this commit breaks the build, because the function definition
of 'keymgr_key_is_successor' changed. This will be fixed in the
following commit.
