The added disable-certificate-events-known-certs.zeek disables repeated
X509 events in SSL connections, given that the connection terminates at
the same server and used the samt SNI as a previously seen connection
with the same certificate.
For people that see significant amounts of TLS 1.2 traffic, this could
reduce the amount of raised events significantly - especially when a
lot of connections are repeat connections to the same servers.
The practical impact of not raising these events is actually very little
- unless a script directly interacts with the x509 events, everything
works as before - the x509 variables in the connection records are still
being set (from the cache).
By default, each certificate is now output only once per hour. This also
should work in cluster mode, where we use the net broker-table-syncing
feature to distribute the information about already seen certificates
across the entire cluster.
Log caching is also pretty configureable and can be changed using a
range of confiuration options and hooks.
Note that this is currently completely separate from X509 events
caching, which prevents duplicate parsing of X509 certificates.
This commit changes the SSL and X.509 logging formats to something that,
hopefully, slowly approaches what they will look like in the future.
X.509 log is not yet deduplicated; this will come in the future.
This commit introduces two new options, which determine if certificate
issuers and subjects are still logged in ssl.log. The default is to have
the host subject/issuer logged, but to remove client-certificate
information. Client-certificates are not a typically used feature
nowadays.
This adds a "policy" hook into the logging framework's streams and
filters to replace the existing log filter predicates. The hook
signature is as follows:
hook(rec: any, id: Log::ID, filter: Log::Filter);
The logging manager invokes hooks on each log record. Hooks can veto
log records via a break, and modify them if necessary. Log filters
inherit the stream-level hook, but can override or remove the hook as
needed.
The distribution's existing log streams now come with pre-defined
hooks that users can add handlers to. Their name is standardized as
"log_policy" by convention, with additional suffixes when a module
provides multiple streams. The following adds a handler to the Conn
module's default log policy hook:
hook Conn::log_policy(rec: Conn::Info, id: Log::ID, filter: Log::Filter)
{
if ( some_veto_reason(rec) )
break;
}
By default, this handler will get invoked for any log filter
associated with the Conn::LOG stream.
The existing predicates are deprecated for removal in 4.1 but continue
to work.
Changed some configuration defaults to potentially more same values.
The callback function is now a hook to allow costomization of the events
that are raised.
Tests now exist. Test baselines are updated.
I moved the replay function to a callback - which now means that the replayed
functions are called before file_state remove. Which makes this virtually
identical with the events raised by the core.
Currently this is mostly missing tests, leak-testing and performance-tests.
This approach mostly relies on script-level changes. In scriptland, we track
which certificates should be cached - and also perform the caching and the
replaying of events there.
This actually is probably nearly functional - the problem is the fact that now
the event ordering is wrong - and file_state_remove is called before the x509
events are thrown.
The fix probably is to move to a callback from the core - which can execute
things in the right order again. (Or just write the whole event-raising inside
the core - but that is both less flexible and a lot more cumbersome).
