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1bd658da8f
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.
71 lines
1.9 KiB
Text
71 lines
1.9 KiB
Text
##! Implementation of the shunt functionality for NetControl.
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module NetControl;
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@load ./main
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export {
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redef enum Log::ID += { SHUNT };
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global log_policy_shunt: Log::PolicyHook;
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## Stops forwarding a uni-directional flow's packets to Zeek.
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##
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## f: The flow to shunt.
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##
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## t: How long to leave the shunt in place, with 0 being indefinitely.
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##
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## location: An optional string describing where the shunt was triggered.
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##
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## Returns: The id of the inserted rule on success and zero on failure.
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global shunt_flow: function(f: flow_id, t: interval, location: string &default="") : string;
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type ShuntInfo: record {
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## Time at which the recorded activity occurred.
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ts: time &log;
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## ID of the rule; unique during each Zeek run.
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rule_id: string &log;
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## Flow ID of the shunted flow.
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f: flow_id &log;
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## Expiry time of the shunt.
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expire: interval &log;
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## Location where the underlying action was triggered.
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location: string &log &optional;
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};
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## Event that can be handled to access the :zeek:type:`NetControl::ShuntInfo`
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## record as it is sent on to the logging framework.
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global log_netcontrol_shunt: event(rec: ShuntInfo);
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}
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event zeek_init() &priority=5
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{
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Log::create_stream(NetControl::SHUNT, [$columns=ShuntInfo, $ev=log_netcontrol_shunt, $path="netcontrol_shunt", $policy=log_policy_shunt]);
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}
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function shunt_flow(f: flow_id, t: interval, location: string &default="") : string
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{
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local flow = NetControl::Flow(
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$src_h=addr_to_subnet(f$src_h),
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$src_p=f$src_p,
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$dst_h=addr_to_subnet(f$dst_h),
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$dst_p=f$dst_p
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);
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local e: Entity = [$ty=FLOW, $flow=flow];
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local r: Rule = [$ty=DROP, $target=MONITOR, $entity=e, $expire=t, $location=location];
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local id = add_rule(r);
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# Error should already be logged
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if ( id == "" )
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return id;
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local log = ShuntInfo($ts=network_time(), $rule_id=id, $f=f, $expire=t);
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if ( location != "" )
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log$location=location;
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Log::write(SHUNT, log);
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return id;
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}
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