From 5d062daf33b21ab68b2b17c85f73d6ea45584af2 Mon Sep 17 00:00:00 2001
From: Vincent Lafeychine <vincent.lafeychine@proton.me>
Date: Sun, 16 Apr 2023 23:11:54 +0200
Subject: [PATCH] Initial DSL

---
 example_rules.py |  65 ++++++++++++++++++++++++
 nftables.py      | 127 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 192 insertions(+)
 create mode 100644 example_rules.py
 create mode 100755 nftables.py

diff --git a/example_rules.py b/example_rules.py
new file mode 100644
index 0000000..ea69f81
--- /dev/null
+++ b/example_rules.py
@@ -0,0 +1,65 @@
+---
+zones:
+  - name: users-internet-allowed
+    include:
+      - rules.yaml
+  - name: mgmt
+    include:
+      - 10.203.0.0/16
+  - name: adm
+    include:
+      - 2a09:6840::/29
+      - 10.128.0.0/16
+  - name: internet
+    exclude:
+      - adm
+      - mgmt
+
+blacklist:
+  enabled: true
+  addr:
+    - 0.0.0.0
+
+reverse_path_filter:
+  enabled: true
+
+filter:
+  input:
+    - iif: lo
+      verdict: accept
+    - src: mgmt
+      protocols:
+        tcp:
+          dport: "22,240..242"
+      verdict: accept
+    - src: backbone
+      protocols:
+        ospf: true
+        vrrp: true
+        tcp:
+            dport: 179
+      verdict: accept
+    - protocols:
+        icmp: true
+      verdict: accept
+  output:
+    - verdict: accept
+  forward:
+    - src: interco-crans
+      verdict: accept
+    - src: users-internet-allowed
+      tcp:
+        dport: 25
+      verdict: drop
+    - src: users-internet-allowed
+      dest:
+        - internet
+        - 10.0.0.1
+      verdict: accept
+
+nat:
+  - src: mgmt
+    snat:
+      addr: 45.66.108.14
+      persistent: true
+...
diff --git a/nftables.py b/nftables.py
new file mode 100755
index 0000000..ee05f5c
--- /dev/null
+++ b/nftables.py
@@ -0,0 +1,127 @@
+#!/usr/bin/env python3
+
+from __future__ import annotations
+from argparse import ArgumentParser, FileType
+from enum import Enum
+from pydantic import BaseModel, FilePath, IPvAnyAddress, IPvAnyNetwork, validator, root_validator
+from yaml import safe_load
+
+def parse_range_string(s):
+    parts = s.split(",")
+    values = []
+
+    for part in parts:
+        if ".." in part:
+            start, end = part.split("..")
+            start = int(start)
+            end = int(end)
+            values += [start + i for i in range(end - start + 1)]
+        else:
+            values.append(int(part))
+
+    return values
+
+# Zones
+
+class ZoneName(str):
+    pass
+
+class Zone(BaseModel):
+    name: ZoneName
+    exclude: list[IPvAnyNetwork | FilePath | ZoneName] | None
+    include: list[IPvAnyNetwork | FilePath | ZoneName] | None
+
+    @root_validator()
+    def validate_mutually_exclusive(cls, values):
+        if values.get("exclude") and values.get("include"):
+            raise ValueError("exclude and include are mutually exclusive")
+        return values
+
+# Blacklist
+
+class BlackList(BaseModel):
+    enabled: bool = False
+    addr: list[IPvAnyAddress] = []
+
+# Reverse Path Filter
+
+class ReversePathFilter(BaseModel):
+    enabled: bool = False
+
+# Filters
+
+class Verdict(str, Enum):
+    accept = "accept"
+    drop = "drop"
+    reject = "reject"
+
+class TcpProtocol(BaseModel):
+    dport: str | None
+    sport: str | None
+
+    @validator("dport", "sport")
+    def parse_range(cls, v):
+        return parse_range_string(v)
+
+class UdpProtocol(BaseModel):
+    dport: str | None
+    sport: str | None
+
+    @validator("dport", "sport")
+    def parse_range(cls, v):
+        return parse_range_string(v)
+
+class Protocols(BaseModel):
+    icmp: bool = False
+    ospf: bool = False
+    tcp: TcpProtocol | None
+    udp: UdpProtocol | None
+    vrrp: bool = False
+
+class Rule(BaseModel):
+    iff: str | None
+    protocols: Protocols = Protocols()
+    src: ZoneName | list[IPvAnyNetwork | FilePath | ZoneName] | None
+    verdict: Verdict = Verdict.accept
+
+class ForwardRule(Rule):
+    dest: ZoneName | list[IPvAnyNetwork | FilePath | ZoneName] | None
+
+class Filter(BaseModel):
+    input: list[Rule] = []
+    output: list[Rule] = []
+    forward: list[ForwardRule] = []
+
+# Nat
+
+class SNat(BaseModel):
+    addr: IPvAnyAddress
+    persistent: bool = True
+
+class Nat(BaseModel):
+    src: ZoneName | list[IPvAnyNetwork | FilePath | ZoneName] | None
+    snat: SNat
+
+# Root model
+
+class Firewall(BaseModel):
+    zones: list[Zone] = []
+    blacklist: BlackList | None
+    reverse_path_filter: ReversePathFilter | None
+    filter: Filter | None
+    nat: list[Nat] = []
+
+def main():
+    parser = ArgumentParser()
+    parser.add_argument("file", type=FileType("r"), help="YAML rule file")
+
+    args = parser.parse_args()
+
+    rules = Firewall(**safe_load(args.file))
+
+    print(rules)
+
+    return 0
+
+if __name__ == "__main__":
+    main()