The named configuration files used in the "geoip2" system test cause a
rather large number of views (6-8) to be set up in each tested named
instance. Each view has its own cache.
Commit aa72c31422 caused the RBT hash
table to be pre-allocated to a size derived from "max-cache-size", so
that it never needs to be rehashed. The size of that hash table is not
expected to be significant enough to cause memory use issues in typical
conditions even for large "max-cache-size" settings.
However, these two factors combined can cause memory exhaustion issues
in GitLab CI, where we run multiple "instances" of the test suite in
parallel on the same runner, each test suite executes multiple system
tests concurrently, and each system test may potentially start multiple
named instances at the same time. In practice, this problem currently
only seems to be affecting the "geoip2" system test, which is failing
intermittently due to named instances used by that test getting killed
by oom-killer.
Prevent the "geoip2" system test from failing intermittently by setting
"max-cache-size" in named configuration files used in that test to a low
value in order to keep memory usage at bay even with a large number of
views configured.
(cherry picked from commit 4292d5bdfe)
In 9.17 we introduced 'primaries' as a synonym for 'masters' in the
configuration file. This synonym has not been backported so change
the serve-stale test to make use of the 'masters' keyword.
Add a fifth named (ns5) that runs with `stale-cache-enable no;` and
check that there are no stale records in the cache.
(cherry picked from commit abc2ab9223)
The current serve-stale implementation in BIND 9 stores all received
records in the cache for a max-stale-ttl interval (default 12 hours).
This allows DNS operators to turn the serve-stale answers in an event of
large authoritative DNS outage. The caching of the stale answers needs
to be enabled before the outage happens or the feature would be
otherwise useless.
The negative consequence of the default setting is the inevitable
cache-bloat that happens for every and each DNS operator running named.
In this MR, a new configuration option `stale-cache-enable` is
introduced that allows the operators to selectively enable or disable
the serve-stale feature of BIND 9 based on their decision.
The newly introduced option has been disabled by default,
e.g. serve-stale is disabled in the default configuration and has to be
enabled if required.
(cherry picked from commit ce53db34d6)
Running system tests with root privileges is potentially dangerous.
Only allow it when explicitly requested (by building with
--enable-developer).
(cherry picked from commit 3ef106f69d)
Created isc_refcount_decrement_expect macro to test conditionally
the return value to ensure it is in expected range. Converted
unchecked isc_refcount_decrement to use isc_refcount_decrement_expect.
Converted INSIST(isc_refcount_decrement()...) to isc_refcount_decrement_expect.
(cherry picked from commit bde5c7632a)
There were several problems with rbt hashtable implementation:
1. Our internal hashing function returns uint64_t value, but it was
silently truncated to unsigned int in dns_name_hash() and
dns_name_fullhash() functions. As the SipHash 2-4 higher bits are
more random, we need to use the upper half of the return value.
2. The hashtable implementation in rbt.c was using modulo to pick the
slot number for the hash table. This has several problems because
modulo is: a) slow, b) oblivious to patterns in the input data. This
could lead to very uneven distribution of the hashed data in the
hashtable. Combined with the single-linked lists we use, it could
really hog-down the lookup and removal of the nodes from the rbt
tree[a]. The Fibonacci Hashing is much better fit for the hashtable
function here. For longer description, read "Fibonacci Hashing: The
Optimization that the World Forgot"[b] or just look at the Linux
kernel. Also this will make Diego very happy :).
3. The hashtable would rehash every time the number of nodes in the rbt
tree would exceed 3 * (hashtable size). The overcommit will make the
uneven distribution in the hashtable even worse, but the main problem
lies in the rehashing - every time the database grows beyond the
limit, each subsequent rehashing will be much slower. The mitigation
here is letting the rbt know how big the cache can grown and
pre-allocate the hashtable to be big enough to actually never need to
rehash. This will consume more memory at the start, but since the
size of the hashtable is capped to `1 << 32` (e.g. 4 mio entries), it
will only consume maximum of 32GB of memory for hashtable in the
worst case (and max-cache-size would need to be set to more than
4TB). Calling the dns_db_adjusthashsize() will also cap the maximum
size of the hashtable to the pre-computed number of bits, so it won't
try to consume more gigabytes of memory than available for the
database.
FIXME: What is the average size of the rbt node that gets hashed? I
chose the pagesize (4k) as initial value to precompute the size of
the hashtable, but the value is based on feeling and not any real
data.
For future work, there are more places where we use result of the hash
value modulo some small number and that would benefit from Fibonacci
Hashing to get better distribution.
Notes:
a. A doubly linked list should be used here to speedup the removal of
the entries from the hashtable.
b. https://probablydance.com/2018/06/16/fibonacci-hashing-the-optimization-that-the-world-forgot-or-a-better-alternative-to-integer-modulo/
(cherry picked from commit e24bc324b4)
server might be created, but not yet fully initialized, when fatal
function is called. Check both server and task before attaching
exclusive task.
(cherry picked from commit c5e7152cf0)
Check that resign interval is actually in days rather than hours
by checking that RRSIGs are all within the allowed day range.
(cherry picked from commit 11ecf7901b)
Since October 2019 I have had complaints from `dnssec-cds` reporting
that the signatures on some of my test zones had expired. These were
zones signed by BIND 9.15 or 9.17, with a DNSKEY TTL of 24h and
`sig-validity-interval 10 8`.
This is the same setup we have used for our production zones since
2015, which is intended to re-sign the zones every 2 days, keeping
at least 8 days signature validity. The SOA expire interval is 7
days, so even in the presence of zone transfer problems, no-one
should ever see expired signatures. (These timers are a bit too
tight to be completely correct, because I should have increased
the expiry timers when I increased the DNSKEY TTLs from 1h to 24h.
But that should only matter when zone transfers are broken, which
was not the case for the error reports that led to this patch.)
For example, this morning my test zone contained:
dev.dns.cam.ac.uk. 86400 IN RRSIG DNSKEY 13 5 86400 (
20200701221418 20200621213022 ...)
But one of my resolvers had cached:
dev.dns.cam.ac.uk. 21424 IN RRSIG DNSKEY 13 5 86400 (
20200622063022 20200612061136 ...)
This TTL was captured at 20200622105807 so the resolver cached the
RRset 64976 seconds previously (18h02m56s), at 20200621165511
only about 12h before expiry.
The other symptom of this error was incorrect `resign` times in
the output from `rndc zonestatus`.
For example, I have configured a test zone
zone fast.dotat.at {
file "../u/z/fast.dotat.at";
type primary;
auto-dnssec maintain;
sig-validity-interval 500 499;
};
The zone is reset to a minimal zone containing only SOA and NS
records, and when `named` starts it loads and signs the zone. After
that, `rndc zonestatus` reports:
next resign node: fast.dotat.at/NS
next resign time: Fri, 28 May 2021 12:48:47 GMT
The resign time should be within the next 24h, but instead it is
near the signature expiry time, which the RRSIG(NS) says is
20210618074847. (Note 499 hours is a bit more than 20 days.)
May/June 2021 is less than 500 days from now because expiry time
jitter is applied to the NS records.
Using this test I bisected this bug to 09990672d which contained a
mistake leading to the resigning interval always being calculated in
hours, when days are expected.
This bug only occurs for configurations that use the two-argument form
of `sig-validity-interval`.
(cherry picked from commit 030674b2a3)
it was possible for the count_newzones() function to try to
unlock view->new_zone_lock on return before locking it, which
caused a crash on shutdown.
(cherry picked from commit ed37c63e2b)
When "rndc reconfig" is run, named first configures a fresh set of views
and then tears down the old views. Consider what happens for a single
view with LMDB enabled; "envA" is the pointer to the LMDB environment
used by the original/old version of the view, "envB" is the pointer to
the same LMDB environment used by the new version of that view:
1. mdb_env_open(envA) is called when the view is first created.
2. "rndc reconfig" is called.
3. mdb_env_open(envB) is called for the new instance of the view.
4. mdb_env_close(envA) is called for the old instance of the view.
This seems to have worked so far. However, an upstream change [1] in
LMDB which will be part of its 0.9.26 release prevents the above
sequence of calls from working as intended because the locktable mutexes
will now get destroyed by the mdb_env_close() call in step 4 above,
causing any subsequent mdb_txn_begin() calls to fail (because all of the
above steps are happening within a single named process).
Preventing the above scenario from happening would require either
redesigning the way we use LMDB in BIND, which is not something we can
easily backport, or redesigning the way BIND carries out its
reconfiguration process, which would be an even more severe change.
To work around the problem, set MDB_NOLOCK when calling mdb_env_open()
to stop LMDB from controlling concurrent access to the database and do
the necessary locking in named instead. Reuse the view->new_zone_lock
mutex for this purpose to prevent the need for modifying struct dns_view
(which would necessitate library API version bumps). Drop use of
MDB_NOTLS as it is made redundant by MDB_NOLOCK: MDB_NOTLS only affects
where LMDB reader locktable slots are stored while MDB_NOLOCK prevents
the reader locktable from being used altogether.
[1] 2fd44e3251
(cherry picked from commit 53120279b5)
BUFSIZ (512 bytes on Windows) may not be enough to fit the status of a
DNSSEC policy and three DNSSEC keys.
Set the size of the relevant buffer to a hardcoded value of 4096 bytes,
which should be enough for most scenarios.
(cherry picked from commit 9347e7db7e)
While the creation and publication times of the various keys
in this policy are nearly at the same time there is a chance that
one key is created a second later than the other.
The `set_keytimes_algorithm_policy` mistakenly set the keytimes
for KEY3 based of the "published" time from KEY2.
(cherry picked from commit 24e07ae98e)
This test ensures that named will correctly shutdown
when receiving multiple control connections after processing
of either "rncd stop" or "kill -SIGTERM" commands.
Before the fix, named was crashing due to a race condition happening
between two threads, one running shutdown logic in named/server.c
and other handling control logic in controlconf.c.
This test tries to reproduce the above scenario by issuing multiple
queries to a target named instance, issuing either rndc stop or kill
-SIGTERM command to the same named instance, then starting multiple rndc
status connections to ensure it is not crashing anymore.
(cherry picked from commit 042e509753)
Due to lack of synchronization, whenever named was being requested to
stop using rndc, controlconf.c module could be trying to access an already
released pointer through named_g_server->interfacemgr in a separate
thread.
The race could only be triggered if named was being shutdown and more
rndc connections were ocurring at the same time.
This fix correctly checks if the server is shutting down before opening
a new rndc connection.
(cherry picked from commit be6cc53ec2)
Implement the 'rndc dnssec -status' command that will output
some information about the key states, such as which policy is
used for the zone, what keys are in use, and when rollover is
scheduled.
Add loose testing in the kasp system test, the actual times are
already tested via key file inspection.
(cherry picked from commit 19ce9ec1d4)
Add the code and documentation required to provide DNSSEC signing
status through rndc. This does not yet show any useful information,
just provide the command that will output some dummy string.
(cherry picked from commit e1ba1bea7c)
Make yaml.load_all() use yaml.SafeLoader to address a warning currently
emitted when bin/tests/system/dnstap/ydump.py is run:
ydump.py:28: YAMLLoadWarning: calling yaml.load_all() without Loader=... is deprecated, as the default Loader is unsafe. Please read https://msg.pyyaml.org/load for full details.
for l in yaml.load_all(f.stdout):
The rndc.conf main header was missing the header markup and that was
breaking the TOC for all manpages in the ARM because sphinx-build
incorrectly remembered the markup for subheader to be ~~~~ instead of
----.
(cherry picked from commit 5c56a0ddbc)
The wait until zones are signed after rndc reconfig is broken
because the zones are already signed before the reconfig. Fix
by having a different way to ensure the signing of the zone is
complete. This does require a call to the "wait_for_done_signing"
function after each "check_keys" call after the ns6 reconfig.
The "wait_for_done_signing" looks for a (newly added) debug log
message that named will output if it is done signing with a certain
key.
(cherry picked from commit a47192ed5b)
Add a note why we don't have a test case for the issue.
It is tricky to write a good test case for this if our tools are
not allowed to create signatures for unsupported algorithms.
(cherry picked from commit c6345fffe9)
enough buffer space. Also change named_os_uname() prototype so
that it is now returning (const char *) rather than (char *). If
uname() is not supported on a UNIX build prepopulate unamebuf[]
with "unknown architecture".
(cherry picked from commit 4bc3de070f)
these keywords were added to the parser as synonyms for "master"
and "slave" but were never hooked in to the configuration of named,
so they were ignored. this has been fixed and the option is now
checked for correctness.
(cherry picked from commit ba31b189b4)
- clone keynode->dsset rather than return a pointer so that thread
use is independent of each other.
- hold a reference to the dsset (keynode) so it can't be deleted
while in use.
- create a new keynode when removing DS records so that dangling
pointers to the deleted records will not occur.
- use a rwlock when accessing the rdatalist to prevent instabilities
when DS records are added.
(cherry picked from commit e5b2eca1d3)
