paperclip/packages/tailscale-https-broker/src/audit.ts

91 lines
2.9 KiB
TypeScript

/**
* Append-only, bounded, redacted security audit (PAP-17050 verdict req #6).
*
* Every allow/deny and mutation outcome emits one event. Lease handles,
* bearer/session material, full environments, and raw unbounded CLI output are
* NEVER logged. All string fields are control-character-sanitized and length
* bounded to defeat log forging.
*/
import { appendFileSync } from "node:fs";
import type { BrokerErrorCode, PeerCredentials } from "./types.js";
const MAX_FIELD_LEN = 256;
export interface AuditEvent {
timestampIso: string;
peer: PeerCredentials | null;
op: string;
runtimeId: string | null;
ports: number[];
requestId: string | null;
decision: "allow" | "deny";
reasonCode: BrokerErrorCode | "ok";
reason: string;
beforeDigest?: string;
afterDigest?: string;
cliExitCategory?: "ok" | "error" | "timeout" | "none";
recovery?: "none" | "quarantine" | "cleanup";
}
/** Strip control chars (defeats newline/log-forging) and bound length. */
export function sanitizeField(value: string): string {
// eslint-disable-next-line no-control-regex
const stripped = value.replace(/[\x00-\x1f\x7f]/g, " ");
return stripped.length > MAX_FIELD_LEN ? `${stripped.slice(0, MAX_FIELD_LEN)}` : stripped;
}
export function formatAuditLine(event: AuditEvent): string {
const safe = {
ts: event.timestampIso,
uid: event.peer?.uid ?? null,
gid: event.peer?.gid ?? null,
pid: event.peer?.pid ?? null,
op: sanitizeField(event.op),
runtimeId: event.runtimeId ? sanitizeField(event.runtimeId) : null,
ports: event.ports.filter((p) => Number.isInteger(p)).slice(0, 8),
requestId: event.requestId ? sanitizeField(event.requestId) : null,
decision: event.decision,
reasonCode: event.reasonCode,
reason: sanitizeField(event.reason),
beforeDigest: event.beforeDigest ? sanitizeField(event.beforeDigest) : undefined,
afterDigest: event.afterDigest ? sanitizeField(event.afterDigest) : undefined,
cliExitCategory: event.cliExitCategory,
recovery: event.recovery,
};
return JSON.stringify(safe);
}
export interface AuditSink {
write(event: AuditEvent): void;
}
/**
* Durable file audit sink. If the recommended `blockOnFailure` is set, a write
* failure throws so the caller can fail the mutation closed rather than mutate
* without a durable record.
*/
export class FileAuditSink implements AuditSink {
constructor(
private readonly path: string,
private readonly blockOnFailure = true,
) {}
write(event: AuditEvent): void {
try {
appendFileSync(this.path, `${formatAuditLine(event)}\n`, { mode: 0o600 });
} catch (error) {
if (this.blockOnFailure) {
throw new Error(`audit sink write failed: ${(error as Error).message}`);
}
}
}
}
/** In-memory sink for tests. */
export class MemoryAuditSink implements AuditSink {
readonly events: AuditEvent[] = [];
write(event: AuditEvent): void {
this.events.push(event);
}
}