Unbound 1.21.0

Unbound 1.21.0

This release has a fix for the CAMP and CacheFlush issues. They have a
low severity for Unbound, since it does not affect Unbound so much.

The Compositional Amplification (CAMP) type of attacks can lead to DoS
attacks against DNS servers. In Unbound legitimate client requests to
the resolvers under typical workload are not directly affected by CAMP
attacks. However we introduce a global quota for 128 outgoing packets
per query (and it's subqueries) that is never reset to prevent the
combination of CAMP with other amplification attacks in the future. We
would like to thank Huayi Duan, Marco Bearzi, Jodok Vieli, and Cagin
Tanir from NetSec group, ETH Zurich for discovering and notifying us
about the issue.

The CacheFlush type of attacks (NSCacheFlush, CNAMECacheFlush) try to
evict cached data by utilizing rogue zones and a steady rogue stream to
a resolver. Based on the zone, the stream, the configured cache size
and the legitimate traffic, Unbound could experience a degradation of
service if a useful entry is evicted and Unbound needs to resolve again.
As a mitigation to the NSCacheFlush attack Unbound is setting a limit
of 20 RRs in an NS RRset. We would like to thank Yehuda Afek, Anat
Bremler-Barr, Shoham Danino and Yuval Shavitt (Tel-Aviv University and
Reichman University) for discovering and notifying us about the issue.

Other fixes in this release are bug fixes. Also the unbound control
commands that flush the cache can clear both the memory and cachedb
module cache. The ipset module can use BSD pf tables. The new option
dnstap-sample-rate: 100 can be used to log 1/N messages, for use in
high volume server environments where the log server does not keep up.

The new DNSSEC key for the root, 38696 from 2024 has been added. It is
added to the default root keys in unbound-anchor. The content can be
inspected with unbound-anchor -l. Older versions of Unbound can keep
up with the root key with auto-trust-anchor-file that has RFC5011
key rollover. Also unbound-anchor can fetch the keys from the website
with a certificate if needed.

For cookie secrets, it is possible to perform rollover. The file
with cookie secret in use and the staging secret is configured
with cookie-secret-file. With the remote control the rollover can be
performed, add_cookie_secret, activate_cookie_secret, drop_cookie_secret
and print_cookie_secrets can be used for that.

Compared to the RC1, the release has a fix for module loading on Windows,
and a spelling correction.

Features

• Fix #1071: [FR] Clear both in-memory and cachedb module cache with
  unbound-control flush* commands.
• Fix #144: Port ipset to BSD pf tables.
• Add dnstap-sample-rate that logs only 1/N messages, for high volume
  server environments. Thanks Dan Luther.
• Add root key 38696 from 2024 for DNSSEC validation. It is added
  to the default root keys in unbound-anchor. The content can be
  inspected with unbound-anchor -l.
• Merge #1090: Cookie secret file. Adds
  cookie-secret-file: "unbound_cookiesecrets.txt" option to store
  cookie secrets for EDNS COOKIE secret rollover. The remote control
  add_cookie_secret, activate_cookie_secret and drop_cookie_secret
  commands can be used for rollover, the command print_cookie_secrets
  shows the values in use.

Bug Fixes

• Fix CAMP issues with global quota. Thanks to Huayi Duan, Marco
  Bearzi, Jodok Vieli, and Cagin Tanir from NetSec group, ETH Zurich.
• Fix CacheFlush issues with limit on NS RRs. Thanks to Yehuda Afek,
  Anat Bremler-Barr, Shoham Danino and Yuval Shavitt (Tel-Aviv
  University and Reichman University).
• Merge #1062: Fix potential overflow bug while parsing port in
  function cfg_mark_ports.
• Fix for #1062: declaration before statement, avoid print of null,
  and redundant check for array size.
• Fix to squelch udp connect errors in the log at low verbosity about
  invalid argument for IPv6 link local addresses.
• Fix when the mesh jostle is exceeded that nameserver targets are
  marked as resolved, so that the lookup is not stuck on the
  requestlist.
• Add missing common functions to tdir tests.
• Merge #1070: Fix rtt assignement for low values of
  infra-cache-max-rtt.
• Merge #1069: Fix unbound-control stdin commands for multi-process
  Unbounds.
• Fix unbound-control commands that read stdin in multi-process
  operation (local_zones_remove, local_zones, local_datas_remove,
  local_datas, view_local_datas_remove, view_local_datas). They will
  be properly distributed to all processes. dump_cache and load_cache
  are no longer supported in multi-process operation.
• Remove testdata/remote-threaded.tdir. testdata/09-unbound-control.tdir
  now checks both single and multi process/thread operation.
• Merge #1073: fix null pointer dereference issue in function
  ub_ctx_set_fwd.
• Fix to print a parse error when config is read with no name for
  a forward-zone, stub-zone or view.
• Fix for parse end of forward-zone, stub-zone and view.
• Fix for #1064: Fix that cachedb expired messages are considered
  insecure, and thus can be served to clients when dnssec is enabled.
• Fix #1059: Intermittent DNS blocking failure with local-zone and
  always_nxdomain. Addition of local_zones dynamically via
  unbound-control was not finding the zone's parent correctly.
• Fix #1064: Unbound 1.20 Cachedb broken?
• Fix unused variable warning on compilation with no thread support.
• unbound-control-setup: check openssl availability before doing
  anything, patch from Michael Tokarev.
• Update patch to remove 'command' shell builtin and update error
  text.
• Fix to enable that SERVFAIL is cached, for a short period, for more
  cases. In the cases where limits are exceeded.
• Fix spelling of tcp-idle-timeout docs, from Michael Tokarev.
• Merge #1078: Only check old pid if no username.
• Fix #1079: tags from tagged rpz zones are no longer honored after
  upgrade from 1.19.3 to 1.20.0.
• Fix for #1079: fix RPZ taglist in iterator callback that no client
  info is like no taglist intersection.
• Fix to squelch connection reset by peer errors from log. And fix
  that the tcp read errors are labeled as initial for the first calls.
• Merge #1080: AddressSanitizer detection in tdir tests and memory leak
  fixes.
• Fix memory leak when reload_keep_cache is used and num-threads
  changes.
• Fix memory leak on exit for unbound-dnstap-socket; creates false
  negatives during testing.
• Fix memory leak in setup of dsa sig.
• Fix typos for 'the the' in text.
• Fix validation for repeated use of a DNAME record.
• Add unit test for validation of repeated use of a DNAME record.
• Fix #1091: Build fails with OpenSSL >= 3.0 built with
  OPENSSL_NO_DEPRECATED.
• Fix #1092: Ubuntu 22.04 Jammy fails to compile unbound 1.20.0; by
  adding helpful text for the Python interpreter version and allowing
  the default pkg-config unavailability error message to be shown.
• Fix pkg-config availability check in dnstap/dnstap.m4 and
  systemd.m4.
• Explicitly set the RD bit for the mesh query flags when prefetching.
  These queries have no waiting client but they need to be treated as
  recursive.
• Fix ip-ratelimit-cookie setting, it was not applied.
• Fix to remove unused include from the readzone test program.
• Fix unused variable warning in do_cache_remove.
• Fix compile warning in worker pthread id printout.
• Add unit test skip files and bison and flex output to gitignore.
• Fix to use modstack_init in zonemd unit test.
• Fix to remove unneeded linebreak in fptr_wlist.c.
• Fix compile warnings in fptr_wlist.c.
• Fix for repeated use of a DNAME record: first overallocate and then
  move the exact size of the init value to avoid false positive heap
  overflow reads from address sanitizers.
• Fix to print details about the failure to lookup a DNSKEY record
  when validation fails due to the missing DNSKEY. Also for key prime
  and DS lookups.
• Fix for neater printout for error for missing DS response.
• Fix neater printout.
• Fix #1099: Unbound core dump on SIGSEGV.
• Fix for #1099: Fix to check for deleted RRset when the contents
  is updated and fetched after it is stored, and also check for a
  changed RRset.
• Don't check for message TTL changes if the RRsets remain the same.
• Fix that validation reason failure that uses string print uses
  separate buffer that is passed, from the scratch validation buffer.
• Fixup algo_needs_reason string buffer length.
• Fix shadowed error string variable in validator dnskey handling.
• Update list of known EDE codes.
• For #773: In contrib/unbound.service.in set unbound to start after
  network-online.target. Also for contrib/unbound_portable.service.in.
• Fix #1103: unbound 1.20.0 segmentation fault with nghttp2.
• For #1103: fix to also drop mesh state reference when a h2 reply is
  dropped.
• Add RPZ tag tests in acl_interface.tdir.
• For #1102: clearer text for using interface-* options for the
  loopback interface.
• For #1103: fix to also drop mesh state reference when the discard
  limit is reached, when there is an error making a new recursion
  state and when the connection is dropped with is_drop.
• For #1103: Fix to drop mesh state reference for the http2 stream
  associated with the reply, not the currently active stream. And
  it does not remove it twice on a mesh_send_reply call. The reply
  h2_stream is NULL when not in use, for more initialisation.
• Fix dnstap wakeup, a running wakeup timer is left to expire and not
  increased, a timer is started when the dtio thread is sleeping,
  the timer set disabled when the dtio thread goes to sleep, and
  after sleep the thread checks to see if there are messages to log
  immediately.
• Merge #1110: Make fallthrough explicit for libworker.c.
• For #1110: Test for fallthrough attribute in configure and add
  fallthrough attribute annotations.
• Fix compile when the compiler does not support the noreturn
  attribute.
• Fix to have empty definition when not supported for weak attribute.
• Fix uninitialized variable warning in create_tcp_accept_sock.
• Fix link of dnstap without openssl.
• Fix link of unbound-dnstap-socket without openssl.
• Fix #1106: ratelimit-below-domain logs the wrong FROM address.
• Cleanup ede.tdir test.
• For #935 and #1104, clarify RPZ order and semantics.
• Fix to document parameters of auth_zone_verify_zonemd_with_key.
• Fix for #1114: Fix that cache fill for forward-host names is
  performed, so that with nonzero target-fetch-policy it fetches
  forwarder addresses and uses them from cache. Also updated that
  delegation point cache fill routines use CDflag for AAAA message
  lookups, so that its negative lookup stops a recursion since the
  cache uses the bit for disambiguation for dns64 but the recursion
  uses CDflag for the AAAA target lookups, so the check correctly
  stops a useless recursion by its cache lookup.
• Fix dnstap test program, cleans up to have clean memory on exit,
  for tap_data_free, does not delete NULL items. Also it does not try
  to free the tail, specifically in the free of the list since that
  picked up the next item in the list for its loop causing invalid
  free. Added internal unit test to unbound-dnstap-socket for that.
• Fix that the worker mem report with alloc stats does not attempt
  to print memory use of forwards and hints if they have been
  deleted already.
• Fix that alloc stats has strdup checks, it stops debuggers from
  complaining about mismatch at free time.
• Fix testbound for alloc stats strdup in util/alloc.c.
• Fix that alloc stats for forwards and hints are printed, and when
  alloc stats is enabled, the unit test for unbound control waits for
  reloads to complete.
• Fix that for windows the module startup is called and sets up
  the module-config.
• Fix spelling for the cache-min-negative-ttl entry in the
  example.conf.