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Make a dummy rule that drops all traffic.

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This commit is contained in:
linse 2019-05-15 00:02:15 +02:00
parent a7ddc548f3
commit 5119a22ca4
1 changed files with 48 additions and 2 deletions
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50
rules.ml
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@ -25,6 +25,47 @@ let externals = [
(* OCaml normally warns if you don't match all fields, but that's OK here. *)
[@@@ocaml.warning "-9"]
module Q = Pf_qubes.Parse_qubes
let dummy_rules =
Pf_qubes.Parse_qubes.([{ action = Drop ;
proto = None ;
specialtarget = None ;
dst = `any ;
dstports = [] ;
icmp_type = None ;
number = 0 ;
}])
(* Does the packet match our rules? *)
let classify_client_packet (info : ([`Client of _], _) Packet.info) rules : Packet.action =
let matches_port dstports (port : int) =
List.exists (fun (Q.Range_inclusive (min, max)) -> (min <= port && port <= max)) dstports
in
let matches_proto rule info = match rule.Pf_qubes.Parse_qubes.proto with
| None -> true
| Some p -> match p, info.proto with
| `tcp, `TCP ports -> matches_port rule.Q.dstports ports.dport
| `udp, `UDP ports -> matches_port rule.Q.dstports ports.dport
| `icmp, `ICMP -> true (* TODO *)
| _, _ -> false
in
let matches_dest rule info = match rule.Pf_qubes.Parse_qubes.dst with
| `any -> true
| `hosts subnet ->
let (`IPv4 (header, _ )) = info.Packet.packet in
Ipaddr.Prefix.mem (V4 header.Ipv4_packet.dst) subnet
in
let action = List.fold_left (fun found rule -> match found with
| Some action -> Some action
| None -> if matches_proto rule info && matches_dest rule info then Some rule.action else None) None rules
in
match action with
| None -> `Drop "No matching rule"
| Some Accept -> `Accept
| Some Drop -> `Drop "Drop rule matched"
(** This function decides what to do with a packet from a client VM.
It takes as input an argument [info] (of type [Packet.info]) describing the
@ -50,10 +91,15 @@ let from_client (info : ([`Client of _], _) Packet.info) : Packet.action =
when not (is_tcp_start packet) -> `Accept
| { dst = `External `GoogleDNS } -> `Drop "block Google DNS"
*)
| { dst = (`External _ | `NetVM) } -> `NAT
| { dst = (`External _ | `NetVM) } ->
begin
match classify_client_packet info dummy_rules with
| `Accept -> `NAT
| `Drop s -> `Drop s
end
| { dst = `Client_gateway; proto = `UDP { dport = 53 } } -> `NAT_to (`NetVM, 53)
| { dst = (`Client_gateway | `Firewall_uplink) } -> `Drop "packet addressed to firewall itself"
| { dst = `Client _ } -> `Drop "prevent communication between client VMs by default"
| { dst = `Client _ } -> classify_client_packet info dummy_rules
(** Decide what to do with a packet received from the outside world.
Note: If the packet matched an existing NAT rule then this isn't called. *)