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)
|
||
|---|---|---|
| .github/workflows | ||
| .gitlab/issue_templates | ||
| .reuse/templates | ||
| bin | ||
| ci | ||
| cocci | ||
| contrib | ||
| doc | ||
| fuzz | ||
| lib | ||
| LICENSES | ||
| tests | ||
| util | ||
| .clang-format | ||
| .clang-format.headers | ||
| .dir-locals.el | ||
| .editorconfig | ||
| .git-blame-ignore-revs | ||
| .gitattributes | ||
| .gitchangelog.rc | ||
| .gitignore | ||
| .gitlab-ci.yml | ||
| .mailmap | ||
| .pylintrc | ||
| .readthedocs.yaml | ||
| .tsan-suppress | ||
| .uncrustify.cfg | ||
| AUTHORS | ||
| bind.keys | ||
| ChangeLog | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| COPYING | ||
| COPYRIGHT | ||
| dangerfile.py | ||
| dnstap.proto | ||
| gcovr.cfg | ||
| LICENSE | ||
| meson.build | ||
| meson.format | ||
| meson.options | ||
| NEWS | ||
| OPTIONS.md | ||
| README.md | ||
| REUSE.toml | ||
| SECURITY.md | ||
| sonar-project.properties | ||
| suppr-lsan.txt | ||
BIND 9
Contents
- Introduction
- Reporting bugs and getting help
- Contributing to BIND
- Building BIND
- Automated testing
- Documentation
- 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.
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:
- General information: CONTRIBUTING.md
- Code of Conduct: CODE_OF_CONDUCT.md
- BIND 9 code style: doc/dev/style.md
- BIND architecture and developer guide: doc/dev/dev.md
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 pytest bin/tests/system. 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 the option -Dcmocka=enabled. Execution of unit tests is done by the
meson's test functionality; run by meson test.
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:
meson setup build
ninja -C build arm-pdf
The above requires TeX Live in order to work. The PDF will be written to
build/arm-pdf/latex/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
-
The original development of BIND 9 was underwritten by the following organizations:
Sun Microsystems, Inc. Hewlett Packard Compaq Computer Corporation IBM Process Software Corporation Silicon Graphics, Inc. Network Associates, Inc. U.S. Defense Information Systems Agency USENIX Association Stichting NLnet - NLnet Foundation Nominum, Inc. -
This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit. https://www.OpenSSL.org/
-
This product includes cryptographic software written by Eric Young (eay@cryptsoft.com).
-
This product includes software written by Tim Hudson (tjh@cryptsoft.com).