The dns_cache_flush() drops the old database and creates a new one, but
it forgets to create the task(s) that runs the node pruning and cleaning
the rbtdb when flushing it next time. This causes the cleaning to skip
cleaning the parent nodes (with .down == NULL) leading to increased
memory usage over time until the database is unable to keep up and just
stays overmem all the time.
(cherry picked from commit 79040a669c)
Previously, rbtdb->task had quantum of 1 because it was originally used
just for freeing RBTDB contents, which can happen on a "best effort"
basis (does not need to be prioritized). However, when tree pruning was
implemented, it also started sending events to that task, enabling the
latter to become clogged up with a significant event backlog because it
only pruned a single RBTDB node per event.
To prioritize tree pruning (as it is necessary for enforcing the
configured memory use limit for the cache memory context), create a
second task with a virtually unlimited quantum (UINT_MAX) and send the
tree-pruning events to this new task, to ensure that all nodes scheduled
for pruning will be processed before further nodes are queued in a
similar fashion.
This change enables dropping the prunenodes list and restoring the
originally-used logic that allocates and sends a separate event for each
node to prune.
(cherry picked from commit 231b2375e5)
Reconstruct the variant of the prune_tree() parent cleaning to consider
all elibible parents in a single loop as we were doing before all the
changes that led to this commit.
Update code comments so that they more precisely describe what the
relevant bits of code actually do.
(cherry picked from commit 3a01c749f9)
It was discovered that the TTL-based cleaning could build up
a significant backlog of the rdataset headers during the periods where
the top of the TTL heap isn't expired yet. Make the TTL-based cleaning
more aggressive by cleaning more headers from the heap when we are
adding new header into the RBTDB.
(cherry picked from commit d8220ca4ca)
(cherry picked from commit b4d9f1cbab)
It was discovered that an expired header could sit on top of the heap
a little longer than desireable. Remove expired headers (headers with
rdh_ttl set to 0) from the heap completely, so they don't block the next
TTL-based cleaning.
(cherry picked from commit a9383e4b95)
(cherry picked from commit 756555dbcf)
Instead of juggling with node locks in a cycle, cleanup the node we are
just pruning and send any the parent that's also subject to the pruning
to the prune tree via normal way (e.g. enqueue pruning on the parent).
This simplifies the code and also spreads the pruning load across more
event loop ticks which is better for lock contention as less things run
in a tight loop.
(cherry picked from commit 0b32d323e0)
(cherry picked from commit a4c225cb6d)
The log message for commit a9af1ac5ae
explained:
In some older BIND 9 branches, the extra queuing overhead eliminated by
this change could be remotely exploited to cause excessive memory use.
Due to architectural shift, this branch is not vulnerable to that issue,
but applying the fix to the latter is nevertheless deemed prudent for
consistency and to make the code future-proof.
However, it turned out that having a single queue for the nodes to be
pruned increased lock contention to a level where cleaning up nodes from
the RBTDB took too long, causing the amount of memory used by the cache
to grow indefinitely over time.
This commit reverts the change to the pruning mechanism introduced by
commit a9af1ac5ae as BIND branches newer
than 9.16 were not affected by the excessive event queueing overhead
issue mentioned in the log message for the above commit.
(cherry picked from commit eed17611d8)
(cherry picked from commit 4b32456705)
dns__cacherbt_expireheader can unlink / free header_prev underneath
it. Use ISC_LIST_TAIL after calling dns__cacherbt_expireheader
instead to get the next pointer to be processed.
(cherry picked from commit 7ce2e86024)
We were missing a test where a single owner name would have multiple
types with a different case. The generated RRSIGs and NSEC records will
then have different case than the signed records and message parser have
to cope with that and treat everything as the same owner.
(cherry picked from commit 14e435b814)
The case insensitive matching in isc_ht was basically completely broken
as only the hashvalue computation was case insensitive, but the key
comparison was always case sensitive.
(cherry picked from commit ec11aa2836)
Don't parse the crypto data before parsing and matching the id and the
algorithm for consecutive DNSKEYs. This allows us to parse the RData
only in case the other parameters match allowing us to skip keys that
are of no interest to us, but still would consume precious CPU time by
parsing possibly garbage with OpenSSL.
Remember the position in the iterator when selecting the next signing
key. This should speed up processing for larger DNSKEY RRSets because
we don't have to iterate from start over and over again.
Change the taskmgr (and thus netmgr) in a way that it supports fast and
slow task queues. The fast queue is used for incoming DNS traffic and
it will pass the processing to the slow queue for sending outgoing DNS
messages and processing resolver messages.
In the future, more tasks might get moved to the slow queues, so the
cached and authoritative DNS traffic can be handled without being slowed
down by operations that take longer time to process.
The fix for CVE-2023-4408 introduced a regression in the message
parser, which could cause a crash if an rdata type that can only
occur in the question was found in another section.
(cherry picked from commit 510f1de8a6)
the fix for CVE-2023-4408 introduced a regression in the message
parser, which could cause a crash if duplicate rdatasets were found
in the question section. this commit ensures that rdatasets are
correctly disassociated and freed when this occurs.
(cherry picked from commit 4c19d35614)
Michał Kępień
Petr Špaček
Ondřej SurýandMichał Kępień
Mark AndrewsandOndřej Surý
Michal Nowak
Aram SargsyanandMichał Kępień
Evan HuntandMichał Kępień
Artem Boldariev
Artem Boldariev