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Aram Sargsyan ee6e7e6d00 Lock the catalog zone when reconfiguring it
A catalog zone is updated in an offloaded thread, which is not
stopped during a reconfiguration in an exclusive mode, and so
can cause a race condition with it.

Waiting for the offloaded threads to complete their work before
entering into the exclusive mode can potentially cause unwanted
delays, because offloaded threads are generally "allowed" to take
a longer amount of time before they complete.

Add a dns_catz_zone_prereconfig()/dns_catz_zone_postreconfig() pair
of functions which currently just lock the catalog zone when
reconfiguring it. The change should eliminate the race.

As a side note, there was already a similar pair of functions,
dns_catz_prereconfig() and dns_catz_postreconfig() which are called
before and after reconfiguring a 'dns_catz_zones_t' object.

Below are the stack traces of the reconfiguration thread which has
asserted, and a catalog zone update thread which was caught in the
middle of its work despite the fact that the exclusive mode is
turned on.

                Stack trace of thread 23859:
                #0  0x00007f80e7b8e52f raise (libc.so.6)
                #1  0x00007f80e7b61e65 abort (libc.so.6)
                #2  0x0000000000422558 assertion_failed (named)
                #3  0x00007f80eaa6799e isc_assertion_failed (libisc-9.18.41.so)
                #4  0x00007f80ea5bc788 dns_catz_entry_getname (libdns-9.18.41.so)
                #5  0x000000000042ce0e catz_reconfigure (named)
                #6  0x000000000042d3c5 configure_catz_zone (named)
                #7  0x000000000042d7a4 configure_catz (named)
                #8  0x0000000000430645 configure_view (named)
                #9  0x000000000043d998 load_configuration (named)
                #10 0x000000000044184f loadconfig (named)
                #11 0x0000000000442525 named_server_reconfigcommand (named)
                #12 0x000000000041b277 named_control_docommand (named)
                #13 0x000000000041c74a control_command (named)
                #14 0x00007f80eaa912ae task_run (libisc-9.18.41.so)
                #15 0x00007f80eaa914cd isc_task_run (libisc-9.18.41.so)
                #16 0x00007f80eaa46435 isc__nm_async_task (libisc-9.18.41.so)
                #17 0x00007f80eaa467aa process_netievent (libisc-9.18.41.so)
                #18 0x00007f80eaa475a6 process_queue (libisc-9.18.41.so)
                #19 0x00007f80eaa46227 process_all_queues (libisc-9.18.41.so)
                #20 0x00007f80eaa462a1 async_cb (libisc-9.18.41.so)
                #21 0x00007f80e8d01893 uv__async_io.part.3 (libuv.so.1)
                #22 0x00007f80e8d13ac4 uv__io_poll (libuv.so.1)
                #23 0x00007f80e8d023fb uv_run (libuv.so.1)
                #24 0x00007f80eaa45ced nm_thread (libisc-9.18.41.so)
                #25 0x00007f80eaa9bda3 isc__trampoline_run (libisc-9.18.41.so)
                #26 0x00007f80e7f1e1ca start_thread (libpthread.so.0)
                #27 0x00007f80e7b798d3 __clone (libc.so.6)
    ...
    ...
                Stack trace of thread 23912:
                #0  0x00007f80ea5bc2da dns_catz_options_setdefault (libdns-9.18.41.so)
                #1  0x00007f80ea5bd411 dns__catz_zones_merge (libdns-9.18.41.so)
                #2  0x00007f80ea5c3c2f dns__catz_update_cb (libdns-9.18.41.so)
                #3  0x00007f80eaa4fee9 isc__nm_work_run (libisc-9.18.41.so)
                #4  0x00007f80eaa9bda3 isc__trampoline_run (libisc-9.18.41.so)
                #5  0x00007f80eaa4ff48 isc__nm_work_cb (libisc-9.18.41.so)
                #6  0x00007f80e8cfc75e worker (libuv.so.1)
                #7  0x00007f80e7f1e1ca start_thread (libpthread.so.0)
                #8  0x00007f80e7b798d3 __clone (libc.so.6)

(cherry picked from commit aed9cafd5c)
2025-12-17 17:48:28 +00:00
.github/workflows Update github actions to trigger on correct branches 2023-03-27 17:09:09 +02:00
.gitlab/issue_templates Update docs and processes to use the new changelog 2024-07-29 14:44:59 +02:00
.reuse/templates Replace .reuse/dep5 with REUSE.toml 2025-09-08 12:15:02 +02:00
bin Lock the catalog zone when reconfiguring it 2025-12-17 17:48:28 +00:00
cocci add spatch to detect implicit bool/int/result cast 2025-11-12 10:32:19 +00:00
conftools/perllib/dnsconf Mark setting operating system limits from named.conf as ancient 2022-12-07 19:40:00 +01:00
contrib Make empty changelog fatal error 2025-06-25 12:08:14 +00:00
doc Merge tag 'v9.20.17' into bind-9.20 2025-12-17 15:33:14 +00:00
fuzz standardize CHECK and RETERR macros 2025-12-03 19:17:20 -08:00
lib Lock the catalog zone when reconfiguring it 2025-12-17 17:48:28 +00:00
LICENSES Change exception SPDX to Autoconf-exception-generic 2024-04-24 09:46:58 +00:00
m4 Print the used jemalloc version in autoconf and named -V output 2023-09-05 18:47:21 +02:00
tests Implement dns_dbiterator_seek3 2025-12-11 13:53:25 +01:00
util check-cocci fails in WARNING is found on stderr 2025-11-12 10:32:20 +00:00
.clang-format Use ControlStatementsExceptControlMacros for SpaceBeforeParens 2025-08-19 08:08:23 +02:00
.clang-format.headers Use ControlStatementsExceptControlMacros for SpaceBeforeParens 2025-08-19 08:08:23 +02:00
.dir-locals.el Remove trailing whitespace from all text files 2023-06-13 15:05:40 +02:00
.editorconfig Add editorconfig file for shell style 2023-10-26 10:23:52 +02:00
.git-blame-ignore-revs Ignore clang-format reformatting commits 2025-08-19 08:09:02 +02:00
.gitattributes Add .sh extension to shell scripts 2025-09-18 15:40:26 +02:00
.gitchangelog.rc Add BIND9 configuration for gitchangelog 2024-07-29 14:44:57 +02:00
.gitignore Add .sh extension to shell scripts 2025-09-18 15:40:26 +02:00
.gitlab-ci.yml Temporarily change pytest.PytestRemovedIn9Warning error to warning 2025-12-16 20:28:55 +00:00
.mailmap Add full Alessio's name to .mailmap to fix some of the older commits 2024-09-26 11:51:08 +00:00
.pylintrc Disable too-many/too-few pylint checks 2024-10-22 09:14:06 +02:00
.readthedocs.yaml Read the Docs should always source requirements.txt from "main" 2024-10-17 10:50:21 +00:00
.tsan-suppress Suppress FreeBSD-specific TSAN false-positive lock-order-inversion 2025-04-02 13:58:55 +00:00
.uncrustify.cfg fix spelling errors reported by Fossies. 2020-02-21 15:05:08 +11:00
AUTHORS Modify AUTHORS 2022-12-20 22:13:53 +02:00
bind.keys Add the DS for the new root key (38696) 2024-11-15 22:32:10 +00:00
ChangeLog Link ChangeLog to doc/arm/changelog.rst 2025-02-28 11:07:53 +00:00
CODE_OF_CONDUCT.md Update the copyright information in all files in the repository 2022-01-11 09:05:02 +01:00
configure.ac Update BIND version for release 2025-12-11 12:28:49 +01:00
CONTRIBUTING.md Update CONTRIBUTING.md and developer doc 2024-12-12 15:18:50 +00:00
COPYING Complete rewrite the BIND 9 build system 2020-04-21 14:19:48 +02:00
COPYRIGHT Remove trailing whitespace from all text files 2023-06-13 15:05:40 +02:00
dangerfile.py Update issue closing regex in dangerfile.py 2025-04-02 13:42:40 +00:00
LICENSE Update the copyright information in all files in the repository 2022-01-11 09:05:02 +01:00
Makefile.am Remove the CHANGES file 2024-10-31 16:46:57 +00:00
Makefile.docs Remove PDF-related bits from the build system 2023-10-12 14:24:42 +02:00
Makefile.dtrace Regenerate the DTrace generated files on configure change 2023-08-23 07:40:20 +02:00
Makefile.tests Link jemalloc again for testing unit build order 2024-01-18 09:34:36 +01:00
Makefile.top Add workaround for jemalloc linking order 2024-01-18 09:34:36 +01:00
NEWS Add new changelog file 2024-07-29 14:44:39 +02:00
OPTIONS.md Document -DOPENSSL_API_COMPAT=10100 in OPTIONS.md 2022-09-23 13:17:55 +10:00
README.md Remove the CHANGES file 2024-10-31 16:46:57 +00:00
REUSE.toml Use jinja2 templates in nsupdate test 2025-12-10 13:43:52 +01:00
SECURITY.md Update URL for bug reports 2025-06-02 07:04:20 +00:00
sonar-project.properties Add SonarCloud GitHub Action 2023-02-24 08:53:41 +00:00
suppr-lsan.txt Supress the leak detection in __xmlDefaultBufferSize 2025-02-04 12:37:53 +00:00

BIND 9

Contents

  1. Introduction
  2. Reporting bugs and getting help
  3. Contributing to BIND
  4. Building BIND
  5. Automated testing
  6. Documentation
  7. Acknowledgments

Introduction

BIND (Berkeley Internet Name Domain) is a complete, highly portable implementation of the Domain Name System (DNS) protocol.

The BIND name server, named, can act as an authoritative name server, recursive resolver, DNS forwarder, or all three simultaneously. It implements views for split-horizon DNS, automatic DNSSEC zone signing and key management, catalog zones to facilitate provisioning of zone data throughout a name server constellation, response policy zones (RPZ) to protect clients from malicious data, response rate limiting (RRL) and recursive query limits to reduce distributed denial of service attacks, and many other advanced DNS features. BIND also includes a suite of administrative tools, including the dig and delv DNS lookup tools, nsupdate for dynamic DNS zone updates, rndc for remote name server administration, and more.

BIND 9 began as a complete rewrite of the BIND architecture that was used in versions 4 and 8. Internet Systems Consortium (https://www.isc.org), a 501(c)(3) US public benefit corporation dedicated to providing software and services in support of the Internet infrastructure, developed BIND 9 and is responsible for its ongoing maintenance and improvement. BIND is open source software licensed under the terms of the Mozilla Public License, version 2.0.

For a detailed list of changes made throughout the history of BIND 9, see the changelog.

For up-to-date versions and release notes, see https://www.isc.org/download/.

For information about supported platforms, see the "Supported Platforms" section in the BIND 9 Administrator Reference Manual.

Reporting bugs and getting help

To report non-security-sensitive bugs or request new features, you may open an issue in the BIND 9 project on the ISC GitLab server at https://gitlab.isc.org/isc-projects/bind9.

Please note that, unless you explicitly mark the newly created issue as "confidential," it will be publicly readable. Please do not include any information in bug reports that you consider to be confidential unless the issue has been marked as such. In particular, if submitting the contents of your configuration file in a non-confidential issue, it is advisable to obscure key secrets; this can be done automatically by using named-checkconf -px.

For information about ISC's Security Vulnerability Disclosure Policy and information about reporting potential security issues, please see SECURITY.md.

Professional support and training for BIND are available from ISC. Contact us at https://www.isc.org/contact for more information.

To join the BIND Users mailing list, or view the archives, visit https://lists.isc.org/mailman/listinfo/bind-users.

If you're planning on making changes to the BIND 9 source code, you may also want to join the BIND Workers mailing list, at https://lists.isc.org/mailman/listinfo/bind-workers.

Contributing to BIND

ISC maintains a public git repository for BIND; details can be found at https://www.isc.org/sourceaccess/.

Information for BIND contributors can be found in the following files:

Patches for BIND may be submitted as merge requests on the ISC GitLab server.

By default, external contributors do not have the ability to fork BIND on the GitLab server; if you wish to contribute code to BIND, you may request permission to do so. Thereafter, you can create git branches and directly submit requests that they be reviewed and merged.

If you prefer, you may also submit code by opening a GitLab issue and including your patch as an attachment, preferably generated by git format-patch.

Building BIND 9

For information about building BIND 9, see the "Building BIND 9" section in the BIND 9 Administrator Reference Manual.

Automated testing

A system test suite can be run with make check. The system tests require you to configure a set of virtual IP addresses on your system (this allows multiple servers to run locally and communicate with each other). These IP addresses can be configured by running the command bin/tests/system/ifconfig.sh up as root.

Some tests require Perl and the Net::DNS and/or IO::Socket::IP modules, and are skipped if these are not available. Some tests require Python and the dnspython module and are skipped if these are not available. See bin/tests/system/README for further details.

Unit tests are implemented using the CMocka unit testing framework. To build them, use configure --with-cmocka. Execution of tests is done by the automake parallel test driver; unit tests are also run by make check.

Documentation

The BIND 9 Administrator Reference Manual (ARM) is included with the source distribution, and in .rst format, in the doc/arm directory. The HTML version is automatically generated and can be viewed at https://bind9.readthedocs.io/en/latest/index.html.

The PDF version can be built by running:

cd doc/arm/
sphinx-build -b latex . pdf/
make -C pdf/ all-pdf

The above requires TeX Live in order to work. The PDF will be written to doc/arm/pdf/Bv9ARM.pdf.

Man pages for some of the programs in the BIND 9 distribution are also included in the BIND ARM.

Frequently (and not-so-frequently) asked questions and their answers can be found in the ISC Knowledgebase at https://kb.isc.org.

Additional information on various subjects can be found in other README files throughout the source tree.

Bug report identifiers

Most notes in the ARM Changelog appendix include a reference to a bug report or issue number. Prior to 2018, these were usually of the form [RT #NNN] and referred to entries in the "bind9-bugs" RT database, which was not open to the public. More recent entries use the form [GL #NNN] or, less often, [GL !NNN], which, respectively, refer to issues or merge requests in the GitLab database. Most of these are publicly readable, unless they include information which is confidential or security-sensitive.

To look up a GitLab issue by its number, use the URL https://gitlab.isc.org/isc-projects/bind9/issues/NNN. To look up a merge request, use https://gitlab.isc.org/isc-projects/bind9/merge_requests/NNN.

In rare cases, an issue or merge request number may be followed with the letter "P". This indicates that the information is in the private ISC GitLab instance, which is not visible to the public.

Acknowledgments