File size: 8,090 Bytes
5d97275 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 | """Enforcement with a conscience: every action has a TTL, an audit record and a backend that can be a dry run.
e = Enforcer(policy, backend="auto") # auto -> nftables | iptables | windows | dryrun (what the host has)
e.apply(ip, action, family, score, reason) # block / rate_limit / challenge; 'monitor' is only logged
e.expire(now) # lifts what has timed out
e.state() # what is in force now (for the report and the proxy's fast path)
Backends only ever touch a dedicated table / chain / rule group named 'dibaguard', never the host's own rules, and
the layer removes what it added. 'challenge' is a mark the HTTP fast path reads (serve a JS/captcha challenge);
'rate_limit' is a mark for the proxy (token bucket per source) and, with nftables, a limit rule.
"""
from __future__ import annotations
import json
import os
import shutil
import subprocess
import time
class Backend:
name = "dryrun"
def __init__(self):
self.log: list = []
def run(self, argv: list[str]) -> bool:
self.log.append(" ".join(argv))
return True
def setup(self) -> None:
pass
def block(self, ip: str, ttl_s: float = 1800) -> bool:
return self.run(["dryrun", "block", ip, f"ttl={int(ttl_s)}"])
def unblock(self, ip: str) -> bool:
return self.run(["dryrun", "unblock", ip])
class _Shell(Backend):
def run(self, argv: list[str]) -> bool:
self.log.append(" ".join(argv))
try:
return subprocess.run(argv, capture_output=True, text=True, timeout=10).returncode == 0
except Exception: # noqa: BLE001
return False
class Nftables(_Shell):
name = "nftables"
def setup(self) -> None:
self.run(["nft", "add", "table", "inet", "dibaguard"])
self.run(["nft", "add", "set", "inet", "dibaguard", "blocked", "{ type ipv4_addr; flags timeout; }"])
self.run(["nft", "add", "set", "inet", "dibaguard", "blocked6", "{ type ipv6_addr; flags timeout; }"])
self.run(["nft", "add", "chain", "inet", "dibaguard", "input", "{ type filter hook input priority -10; }"])
self.run(["nft", "add", "rule", "inet", "dibaguard", "input", "ip", "saddr", "@blocked", "drop"])
self.run(["nft", "add", "rule", "inet", "dibaguard", "input", "ip6", "saddr", "@blocked6", "drop"])
def block(self, ip: str, ttl_s: float = 1800) -> bool:
s = "blocked6" if ":" in ip else "blocked"
return self.run(["nft", "add", "element", "inet", "dibaguard", s, f"{{ {ip} timeout {int(ttl_s)}s }}"])
def unblock(self, ip: str) -> bool:
s = "blocked6" if ":" in ip else "blocked"
return self.run(["nft", "delete", "element", "inet", "dibaguard", s, f"{{ {ip} }}"])
class Iptables(_Shell):
name = "iptables"
def setup(self) -> None:
self.run(["iptables", "-N", "DIBAGUARD"])
self.run(["iptables", "-C", "INPUT", "-j", "DIBAGUARD"]) or self.run(["iptables", "-I", "INPUT", "-j", "DIBAGUARD"])
def block(self, ip: str, ttl_s: float = 1800) -> bool:
return self.run(["iptables", "-A", "DIBAGUARD", "-s", ip, "-j", "DROP"])
def unblock(self, ip: str) -> bool:
return self.run(["iptables", "-D", "DIBAGUARD", "-s", ip, "-j", "DROP"])
class WindowsFirewall(_Shell):
name = "windows"
def block(self, ip: str, ttl_s: float = 1800) -> bool:
return self.run(["netsh", "advfirewall", "firewall", "add", "rule", f"name=dibaguard-{ip}", "dir=in", "action=block", f"remoteip={ip}"])
def unblock(self, ip: str) -> bool:
return self.run(["netsh", "advfirewall", "firewall", "delete", "rule", f"name=dibaguard-{ip}"])
def pick_backend(name: str = "auto") -> Backend:
if name == "dryrun":
return Backend()
if name in ("auto", "nftables") and shutil.which("nft"):
return Nftables()
if name in ("auto", "iptables") and shutil.which("iptables"):
return Iptables()
if name in ("auto", "windows") and os.name == "nt" and shutil.which("netsh"):
return WindowsFirewall()
return Backend()
class Enforcer:
def __init__(self, policy, backend: str = "auto", audit_path: str | None = None):
self.policy = policy
self.backend = pick_backend(backend if policy.enforcing else "dryrun")
self.backend.setup()
self.active: dict = {} # ip -> {"action", "until", "family", "score", "reason", "since"}
self.audit_path = audit_path
self.audit: list = []
def _record(self, ev: dict) -> None:
ev = dict(ev, ts=time.time(), mode=self.policy.d["mode"], backend=self.backend.name)
self.audit.append(ev)
if len(self.audit) > 100_000:
del self.audit[:50_000]
if self.audit_path:
try:
with open(self.audit_path, "a", encoding="utf-8") as f:
f.write(json.dumps(ev, ensure_ascii=False) + "\n")
except OSError:
pass
def key(self, ip: str, action: str) -> str:
"""what an action is keyed on: an IPv6 block covers the address's /64 (policy ipv6_block_prefix, default 64) -
one host owns a /64 and rotating inside it is free; challenges and rate limits stay per address"""
pfx = int(self.policy.d.get("ipv6_block_prefix", 64))
if action == "block" and ":" in ip and "/" not in ip and pfx < 128:
import ipaddress
try:
a = ipaddress.ip_address(ip)
if a.version == 6 and a.ipv4_mapped is None:
return str(ipaddress.ip_network(f"{ip}/{pfx}", strict=False))
except ValueError:
pass
return ip
def apply(self, ip: str, action: str, family: str, score: int, reason: str = "", now: float | None = None) -> dict:
"""take (or in report mode, record) the policy's action for a verdict; stronger actions replace weaker ones"""
now = time.time() if now is None else now
rank = {"monitor": 0, "rate_limit": 1, "challenge": 2, "block": 3}
if action == "monitor" or self.policy.allowed(ip):
ev = {"ip": ip, "action": "monitor", "family": family, "score": score, "reason": reason, "taken": False}
self._record(ev)
return ev
ip = self.key(ip, action)
cur = self.active.get(ip)
if cur and rank[cur["action"]] >= rank[action]:
cur["until"] = max(cur["until"], now + self.policy.ttl(action))
return dict(cur, ip=ip, taken=False, extended=True)
taken = False
if self.policy.enforcing and action == "block":
taken = self.backend.block(ip, self.policy.ttl("block"))
self.active[ip] = {"action": action, "until": now + self.policy.ttl(action), "family": family, "score": score, "reason": reason, "since": now}
ev = {"ip": ip, "action": action, "family": family, "score": score, "reason": reason, "taken": taken, "ttl_s": self.policy.ttl(action)}
self._record(ev)
return ev
def expire(self, now: float | None = None) -> list:
now = time.time() if now is None else now
lifted = [ip for ip, st in self.active.items() if st["until"] <= now]
for ip in lifted:
st = self.active.pop(ip)
if self.policy.enforcing and st["action"] == "block":
self.backend.unblock(ip)
self._record({"ip": ip, "action": "lift", "family": st["family"], "score": st["score"], "reason": "ttl", "taken": self.policy.enforcing})
return lifted
def state(self) -> dict:
"""what the fast path needs: blocked / challenged / rate-limited sources with their deadlines"""
out = {"block": {}, "challenge": {}, "rate_limit": {}}
for ip, st in self.active.items():
out[st["action"]][ip] = st["until"]
return out
def lookup(self, ip: str) -> str:
st = self.active.get(ip) or self.active.get(self.key(ip, "block"))
return st["action"] if st else "allow"
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