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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.
112 lines
3.3 KiB
Text
112 lines
3.3 KiB
Text
##! Implementation of the drop functionality for NetControl.
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@load ./main
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module NetControl;
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export {
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redef enum Log::ID += { DROP_LOG };
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global log_policy_drop: Log::PolicyHook;
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## Stops all packets involving an IP address from being forwarded.
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##
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## a: The address to be dropped.
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##
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## t: How long to drop it, with 0 being indefinitely.
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##
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## location: An optional string describing where the drop 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 drop_address: function(a: addr, t: interval, location: string &default="") : string;
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## Stops all packets involving a connection address from being forwarded.
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##
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## c: The connection to be dropped.
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##
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## t: How long to drop it, with 0 being indefinitely.
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##
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## location: An optional string describing where the drop 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 drop_connection: function(c: conn_id, t: interval, location: string &default="") : string;
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type DropInfo: 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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orig_h: addr &log; ##< The originator's IP address.
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orig_p: port &log &optional; ##< The originator's port number.
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resp_h: addr &log &optional; ##< The responder's IP address.
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resp_p: port &log &optional; ##< The responder's port number.
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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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## Hook that allows the modification of rules passed to drop_* before they
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## are passed on. If one of the hooks uses break, the rule is ignored.
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##
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## r: The rule to be added.
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global NetControl::drop_rule_policy: hook(r: Rule);
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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_drop: event(rec: DropInfo);
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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::DROP_LOG, [$columns=DropInfo, $ev=log_netcontrol_drop, $path="netcontrol_drop", $policy=log_policy_drop]);
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}
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function drop_connection(c: conn_id, t: interval, location: string &default="") : string
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{
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local e: Entity = [$ty=CONNECTION, $conn=c];
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local r: Rule = [$ty=DROP, $target=FORWARD, $entity=e, $expire=t, $location=location];
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if ( ! hook NetControl::drop_rule_policy(r) )
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return "";
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local id = add_rule(r);
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# Error should already be logged
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if ( id == "" )
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return id;
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local log = DropInfo($ts=network_time(), $rule_id=id, $orig_h=c$orig_h, $orig_p=c$orig_p, $resp_h=c$resp_h, $resp_p=c$resp_p, $expire=t);
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if ( location != "" )
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log$location=location;
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Log::write(DROP_LOG, log);
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return id;
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}
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function drop_address(a: addr, t: interval, location: string &default="") : string
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{
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local e: Entity = [$ty=ADDRESS, $ip=addr_to_subnet(a)];
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local r: Rule = [$ty=DROP, $target=FORWARD, $entity=e, $expire=t, $location=location];
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if ( ! hook NetControl::drop_rule_policy(r) )
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return "";
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local id = add_rule(r);
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# Error should already be logged
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if ( id == "" )
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return id;
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local log = DropInfo($ts=network_time(), $rule_id=id, $orig_h=a, $expire=t);
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if ( location != "" )
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log$location=location;
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Log::write(DROP_LOG, log);
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return id;
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}
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