Instead of disabling the fragmentation on the UDP sockets, we now
disable the Path MTU Discovery by setting IP(V6)_MTU_DISCOVER socket
option to IP_PMTUDISC_OMIT on Linux and disabling IP(V6)_DONTFRAG socket
option on FreeBSD. This option sets DF=0 in the IP header and also
ignores the Path MTU Discovery.
As additional mitigation on Linux, we recommend setting
net.ipv4.ip_no_pmtu_disc to Mode 3:
Mode 3 is a hardend pmtu discover mode. The kernel will only accept
fragmentation-needed errors if the underlying protocol can verify
them besides a plain socket lookup. Current protocols for which pmtu
events will be honored are TCP, SCTP and DCCP as they verify
e.g. the sequence number or the association. This mode should not be
enabled globally but is only intended to secure e.g. name servers in
namespaces where TCP path mtu must still work but path MTU
information of other protocols should be discarded. If enabled
globally this mode could break other protocols.
The client->rcode_override was originally created to force the server
to send SERVFAIL in some cases when it would normally have sent FORMERR.
More recently, it was used in a3ba95116e
commit (part of GL #2790) to force the sending of a TC=1 NOERROR
response, triggering a retry via TCP, when a UDP packet could not be
sent due to ISC_R_MAXSIZE.
This ran afoul of a pre-existing INSIST in ns_client_error() when
RRL was in use. the INSIST was based on the assumption that
ns_client_error() could never result in a non-error rcode. as
that assumption is no longer valid, the INSIST has been removed.
where <value> may be a quoted string. Previously quoted string
only supported opening quotes at the start of the string.
(cherry picked from commit 42c22670b3)
string.endswith("label.sequence") doesn't check for the implict
period before "label.sequence" when matching longer strings.
"foo.label.sequence" should match but "foolabel.sequence shouldn't".
(cherry picked from commit f79876b2d5)
When looking up a zonecut in cache, we use 'dns_rbt_findnode' to find
the closest matching node. This function however does not take into
account stale nodes. When we do find a stale node and use it, this
has implications for subsequent lookups. For example, this may break
QNAME minimization because we are using a deeper zonecut than we should
have.
Check the header for staleness and if so, and stale entries are not
accepted, look for the deepest zonecut from this node up.
(cherry picked from commit bc448fb3b1)
There are some occurrences where we check if a header exists in the
rbtdb. These cases require that the header is also not marked as
ancient (aka ready for cleanup). These cases involve finding certain
data in cache.
(cherry picked from commit e2d4896864)
Add test cases for GL #2665: The QNAME minimization (if enabled) should
also occur on the second query, after the RRsets have expired from
cache. BIND will still have the entries in cache, but marked stale.
These stale entries should not prevent the resolver from minimizing
the QNAME. We query for the test domain a.b.stale. in all cases (QNAME
minimization off, strict mode, and relaxed mode) and expect it to
behave the same the second time we have a stale delegation structure in
cache.
(cherry picked from commit 322626ab5b)
When copying metadata from one dst_key to another, when the source
dst_key has a boolean metadata unset, the destination dst_key will
have a numeric metadata unset instead.
This means that if a key has KSK or ZSK unset, we may be clearing the
Predecessor or Successor metadata in the destination dst_key.
(cherry picked from commit 94bb545087)
Add a test case to the dnssec system test to check that:
- a zone with a prepublished key is only signed with the active key.
- a zone with an inactive key but valid signatures retains those
signatures and does not add signatures from successor key.
- signatures are swapped in a zone when signatures of predecessor
inactive key are within the refresh interval.
(cherry picked from commit 35efbc270f)
When signing with a ZSK, check if it has a predecessor. If so, and if
the predecessor key is sane (same algorithm, key id matches predecessor
value, is zsk), check if the RRset is signed with this key. If so, skip
signing with this successor key. Otherwise, do sign with the successor
key.
This change means we also need to apply the interval to keys that are
not actively signing. In other words, 'expired' is always
'isc_serial_gt(now + cycle, rrsig.timeexpire)'.
Fix a print style issue ("removing signature by ..." was untabbed).
(cherry picked from commit 837adb93d3)
In the "Migrating from NSEC to NSEC3" section, it says:
dnssec-policy "standard" {
nsec3param iterations optout no salt-length 16;
};
There should be an integer after "iterations". Based on the following
text, the number of iterations should be 10.
(cherry picked from commit 9e109191cc)
