MAX_RESTARTS is no longer hard-coded; ns_server_setmaxrestarts()
and dns_client_setmaxrestarts() can now be used to modify the
max-restarts value at runtime. in both cases, the default is 11.
(cherry picked from commit c5588babaf)
the number of steps that can be followed in a CNAME chain
before terminating the lookup has been reduced from 16 to 11.
(this is a hard-coded value, but will be made configurable later.)
(cherry picked from commit 05d78671bb)
Due to the maximum query restart limitation a long CNAME chain
it is cut after 16 queries but named still returns NOERROR.
Return SERVFAIL instead and the partial answer.
(cherry picked from commit b621f1d88e)
When sending fails, the ns__client_request() would not reset the
connection and continue as nothing is happening. This comes from the
model that we don't care about failed UDP sends because datagrams are
unreliable anyway, but it greatly affects TCP connections with
keep-alive.
The worst case scenario is as follows:
1. the 3-way TCP handshake gets completed
2. the libuv calls the "uv_connection_cb" callback
3. the TCP connection gets queue because of the tcp-clients quota
4. the TCP client sends as many DNS messages as the buffers allow
5. the TCP connection gets dropped by the client due to the timeout
6. the TCP connection gets accepted by the server
7. the data already sent by the client gets read
8. all sending fails immediately because the TCP connection is dead
9. we consume all the data in the buffer in a very tight loop
As it doesn't make sense to trying to process more data on the TCP
connection when the sending is failing, drop the connection immediately
on the first sending error.
(cherry picked from commit bf9fd2a6ff)
Clear qctx->zversion when clearing qctx->zrdataset et al in
lib/ns/query.c:qctx_freedata. The uncleared pointer could lead to
an assertion failure if zone data needed to be re-saved which could
happen with stale data support enabled.
(cherry picked from commit 179fb3532ab8d4898ab070b2db54c0ce872ef709)
The new "too many records" error can make an update fail without the
error being logged. This commit fixes that.
(cherry picked from commit 558923e5405894cf976d102f0d246a28bdbb400c)
As a single thread can process only one TCP send at the time, we don't
really need a memory pool for the TCP buffers, but it's enough to have
a single per-loop (client manager) static buffer that's being used to
assemble the DNS message and then it gets copied into own sending
buffer.
In the future, this should get optimized by exposing the uv_try API
from the network manager, and first try to send the message directly
and allocate the sending buffer only if we need to send the data
asynchronously.
(cherry picked from commit 297cc840fbaf34b9dfa1d02d88a023cd5bf5dc4a)
Constantly allocating, reallocating and deallocating 64K TCP send
buffers by 'ns_client' instances takes too much CPU time.
There is an existing mechanism to reuse the ns_clent_t structure
associated with the handle using 'isc_nmhandle_getdata/_setdata'
(see ns_client_request()), but it doesn't work with TCP, because
every time ns_client_request() is called it gets a new handle even
for the same TCP connection, see the comments in
streamdns_on_complete_dnsmessage().
To solve the problem, we introduce an array of available (unused)
TCP buffers stored in ns_clientmgr_t structure so that a 'client'
working via TCP can have a chance to reuse one (if there is one)
instead of allocating a new one every time.
An RPZ response's SOA record TTL is set to 1 instead of the SOA TTL,
a boolean value is passed on to query_addsoa, which is supposed to be
a TTL value. I don't see what value is appropriate to be used for
overriding, so we will pass UINT32_MAX.
(cherry picked from commit 5d7e613e81)
Use the (1 << N) form for defining the flags, in order to avoid
errors like the one fixed in the previous commit.
Also convert the definitions to an enum, as done in some of our
recent refactoring work.
(cherry picked from commit 0d7c7777da)
The DNS_GETDB_STALEFIRST flag is defined as 0x0C, which is the
combination of the DNS_GETDB_PARTIAL (0x04) and the
DNS_GETDB_IGNOREACL (0x08) flags (0x04 | 0x08 == 0x0C) , which is
an obvious error.
All the flags should be power of two, so they don't interfere with
each other. Fix the DNS_GETDB_STALEFIRST flag by setting it to 0x10.
(cherry picked from commit be7d8fafe2)
The older version of the code was reporting that listeners are going
to be of the same type after reconfiguration when switching from DoT
to HTTPS listener, making BIND abort its executions.
That was happening due to the flaw in logic due to which the code
could consider a current listener and a configuration for the new one
to be of the same type (DoT) even when the new listener entry is
explicitly marked as HTTP.
The checks for PROXY in between the configuration were masking that
behaviour, but when porting it to 9.18 (when there is no PROXY
support), the behaviour was exposed.
Now the code mirrors the logic in 'interface_setup()' closely (as it
was meant to).
(cherry picked from commit 8ae661048d)
This commit ensures that listeners are recreated on reconfiguration in
the case when their type changes (or when PROXY protocol type changes,
too).
Previously, if a "listen-on" statement was modified to represent a
different transport, BIND would not pick-up the change on
reconfiguration if listener type changes (e.g. DoH -> DoT) for a given
interface address and port combination. This commit fixes that by
recreating the listener.
Initially, that worked for most of the new transports as we would
recreate listeners on each reconfiguration for DoH and DoT. But at
some point we changed that in such a way that listeners were not
recreated to avoid rebinding a port as on some platforms only root can
do that for port numbers <1000, making some ports binding possible
only on start-up. We chose to asynchronously update listener socket
settings (like TLS contexts, HTTP settings) instead.
Now, we both avoid recreating the sockets if unnecessary and recreate
listeners when listener type changes.
(cherry picked from commit d59cf5e0ce)
When processing UPDATE request DNSKEY, CDNSKEY and CDS record that
are managed by named are filtered out. The log message has been
updated to report the actual type rather that just DNSKEY.
(cherry picked from commit 2cf6cf967d)
The following code block repeats quite often:
if (rdata.type == dns_rdatatype_dnskey ||
rdata.type == dns_rdatatype_cdnskey ||
rdata.type == dns_rdatatype_cds)
Introduce a new function to reduce the repetition.
(cherry picked from commit ef58f2444f)
If we are in the process of looking for the A records as part of
dns64 processing and the server-stale timeout triggers, redo the
dns64 changes that had been made to the orignal qctx.
(cherry picked from commit 1fcc483df1)
The wrong result value was being saved for resumption with
nxdomain-redirect when performing the fetch. This lead to an assert
when checking that RFC 1918 reverse queries where not leaking to
the global internet.
(cherry picked from commit 9d0fa07c5e)
When serve-stale is enabled and recursive resolution fails, the fallback
to lookup stale data always happens in the cache database. Any
authoritative data is ignored, and only information learned through
recursive resolution is examined.
If there is data in the cache that could lead to an answer, and this can
be just the root delegation, the resolver will iterate further, getting
closer to the answer that can be found by recursing down the root, and
eventually puts the final response in the cache.
Change the fallback to serve-stale to use 'query_getdb()', that finds
out the best matching database for the given query.
(cherry picked from commit 2322425016)
All these pointers are guaranteed to be non-NULL.
Additionally, update a comment to remove obviously outdated
information about the function's requirements.
(cherry picked from commit b970556f21)
In the ns__client_put_cb() callback function the 'client->manager'
pointer is guaranteed to be non-NULL, because in ns__client_request(),
before setting up the callback, the ns__client_setup() function is
called for the 'client', which makes sure that 'client->manager' is set.
Removing the NULL-check resolves the following static analyzer warning:
/lib/ns/client.c: 1675 in ns__client_put_cb()
1669 dns_message_puttemprdataset(client->message, &client->opt);
1670 }
1671 client_extendederror_reset(client);
1672
1673 dns_message_detach(&client->message);
1674
>>> CID 465168: Null pointer dereferences (REVERSE_INULL)
>>> Null-checking "client->manager" suggests that it may be null, but it has already been dereferenced on all paths leading to the check.
1675 if (client->manager != NULL) {
1676 ns_clientmgr_detach(&client->manager);
1677 }
1678
1679 /*
1680 * Detaching the task must be done after unlinking from
rr_exists errored if the name did not exist in the zone. This was
not an issue prior to the addition of krb5-subdomain-self-rhs and
ms-subdomain-self-rhs as the only name used was the zone name which
always existed.
(cherry picked from commit b76a15977a)
when synthesizing a new CNAME, we now check whether the target
matches the query already being processed. if so, we do not
restart the query; this prevents a waste of resources.
(cherry picked from commit 0ae8b2e056)
The 'refresh_rrset' variable is used to determine if we can detach from
the client. This can cause a hang on shutdown. To fix this, move setting
of the 'nodetach' variable up to where 'refresh_rrset' is set (in
query_lookup(), and thus not in ns_query_done()), and set it to false
when actually refreshing the RRset, so that when this lookup is
completed, the client will be detached.
When a query was aborted because of the recursion quota being exceeded,
but triggered a stale answer response and a stale data refresh query,
it could cause named to loop back where we are iterating and following
a delegation. Having no good answer in cache, we would fall back to
using serve-stale again, use the stale data, try to refresh the RRset,
and loop back again, without ever terminating until crashing due to
stack overflow.
This happens because in the functions 'query_notfound()' and
'query_delegation_recurse()', we check whether we can fall back to
serving stale data. We shouldn't do so if we are already refreshing
an RRset due to having prioritized stale data in cache.
In other words, we need to add an extra check to 'query_usestale()' to
disallow serving stale data if we are currently refreshing a stale
RRset.
As an additional mitigation to prevent looping, we now use the result
code ISC_R_ALREADYRUNNING rather than ISC_R_FAILURE when a recursion
loop is encountered, and we check for that condition in
'query_usestale()' as well.
This commit changes send buffers allocation strategy for stream based
transports. Before that change we would allocate a dynamic buffers
sized at 64Kb even when we do not need that much. That could lead to
high memory usage on server. Now we resize the send buffer to match
the size of the actual data, freeing the memory at the end of the
buffer for being reused later.
(cherry picked from commit d8a5feb556)
We recently fixed a bug where in some cases (when following an
expired CNAME for example), named could return SERVFAIL if the target
record is still valid (see isc-projects/bind9#3678, and
isc-projects/bind9!7096). We fixed this by considering non-stale
RRsets as well during the stale lookup.
However, this triggered a new bug because despite the answer from
cache not being stale, the lookup may be triggered by serve-stale.
If the answer from database is not stale, the fix in
isc-projects/bind9!7096 erroneously skips the serve-stale logic.
Add 'answer_found' checks to the serve-stale logic to fix this issue.
(cherry picked from commit bbd163acf6)
'-T transferinsecs' makes named interpret the max-transfer-time-out,
max-transfer-idle-out, max-transfer-time-in and max-transfer-idle-in
configuration options as seconds instead of minutes.
'-T transferslowly' makes named to sleep for one second for every
xfrout message.
'-T transferstuck' makes named to sleep for one minute for every
xfrout message.
(cherry picked from commit dfaecfd752)
this function was just a front-end for gethostname(). it was
needed when we supported windows, which has a different function
for looking up the hostname; it's not needed any longer.
(cherry picked from commit 197334464e)
Instead of using an extra rarely-used paramater to dns_clientinfo_init()
to set ECS information for a client, this commit adds a function
dns_clientinfo_setecs() which can be called only when ECS is needed.
(cherry picked from commit ff3fdaa424)
Return 'isc_result_t' type value instead of 'bool' to indicate
the actual failure. Rename the function to something not suggesting
a boolean type result. Make changes in the places where the API
function is being used to check for the result code instead of
a boolean value.
(cherry picked from commit 41dc48bfd7)
Although 'dns_fetch_t' fetch can have two associated events, one for
each of 'DNS_EVENT_FETCHDONE' and 'DNS_EVENT_TRYSTALE' types, the
dns_resolver_cancelfetch() function is designed in a way that it
expects only one existing event, which it must cancel, and when it
happens so that 'stale-answer-client-timeout' is enabled and there
are two events, only one of them is canceled, and it results in an
assertion in dns_resolver_destroyfetch(), when it finds a dangling
event.
Change the logic of dns_resolver_cancelfetch() function so that it
cancels both the events (if they exist), and in the right order.
(cherry picked from commit ec2098ca35)
dns_db_findext() asserts if RRSIG is passed to it and
query_lookup_stale() failed to map RRSIG to ANY to prevent this. To
avoid cases like this in the future, move the mapping of SIG and RRSIG
to ANY for qctx->type to qctx_init().
(cherry picked from commit 56eae06418)
check allow-update, update-policy, and allow-update-forwarding before
consuming quota slots, so that unauthorized clients can't fill the
quota.
(this moves the access check before the prerequisite check, which
violates the precise wording of RFC 2136. however, RFC co-author Paul
Vixie has stated that the RFC is mistaken on this point; it should have
said that access checking must happen *no later than* the completion of
prerequisite checks, not that it must happen exactly then.)
(cherry picked from commit 964f559edb)
limit the number of simultaneous DNS UPDATE events that can be
processed by adding a quota for update and update forwarding.
this quota currently, arbitrarily, defaults to 100.
also add a statistics counter to record when the update quota
has been exceeded.
(cherry picked from commit 7c47254a14)
The ns_client_aclchecksilent is used to check multiple ACLs before
the decision is made that a query is denied. It is also used to
determine if recursion is available. In those cases we should not
set the extended DNS error "Prohibited".
(cherry picked from commit 798c8f57d4)
DSCP has not been fully working since the network manager was
introduced in 9.16, and has been completely broken since 9.18.
This seems to have caused very few difficulties for anyone,
so we have now marked it as obsolete and removed the
implementation.
To ensure that old config files don't fail, the code to parse
dscp key-value pairs is still present, but a warning is logged
that the feature is obsolete and should not be used. Nothing is
done with configured values, and there is no longer any
range checking.
(cherry picked from commit 916ea26ead)
Commit 9ffb4a7ba1 causes Clang Static
Analyzer to flag a potential NULL dereference in query_nxdomain():
query.c:9394:26: warning: Dereference of null pointer [core.NullDereference]
if (!qctx->nxrewrite || qctx->rpz_st->m.rpz->addsoa) {
^~~~~~~~~~~~~~~~~~~
1 warning generated.
The warning above is for qctx->rpz_st potentially being a NULL pointer
when query_nxdomain() is called from query_resume(). This is a false
positive because none of the database lookup result codes currently
causing query_nxdomain() to be called (DNS_R_EMPTYWILD, DNS_R_NXDOMAIN)
can be returned by a database lookup following a recursive resolution
attempt. Add a NULL check nevertheless in order to future-proof the
code and silence Clang Static Analyzer.
(cherry picked from commit 07592d1315)
(cherry picked from commit a4547a1093)
With 'stale-answer-enable yes;' and 'stale-answer-client-timeout off;',
consider the following situation:
A CNAME record and its target record are in the cache, then the CNAME
record expires, but the target record is still valid.
When a new query for the CNAME record arrives, and the query fails,
the stale record is used, and then the query "restarts" to follow
the CNAME target. The problem is that the query's multiple stale
options (like DNS_DBFIND_STALEOK) are not reset, so 'query_lookup()'
treats the restarted query as a lookup following a failed lookup,
and returns a SERVFAIL answer when there is no stale data found in the
cache, even if there is valid non-stale data there available.
With this change, query_lookup() now considers non-stale data in the
cache in the first place, and returns it if it is available.
(cherry picked from commit 91a1a8efc5)
This commit fixes TLS session resumption via session IDs when
client certificates are used. To do so it makes sure that session ID
contexts are set within server TLS contexts. See OpenSSL documentation
for 'SSL_CTX_set_session_id_context()', the "Warnings" section.
(cherry picked from commit 837fef78b1)
