From 12124aaad8233c32c1c10cb7e4b9f0e9c8bf8a79 Mon Sep 17 00:00:00 2001
From: Diego Rodrigues de Sa e Souza
 <8016841+diegosouzapw@users.noreply.github.com>
Date: Thu, 18 Jun 2026 20:18:01 -0300
Subject: [PATCH] feat(mitm): local-only route + trust-store installer for
 TPROXY decrypt (4b/N) (#4211)

Integrated into release/v3.8.29 (round 7). TPROXY decrypt 4b/N: local-only route (/api/tools/agent-bridge/tproxy, LOCAL_ONLY per routeGuard) + dedicated trust-store CA installer (execFileWithPassword, no shell). Validated locally: 12/12 tests + typecheck:core clean (test-unit does not run on release PRs).
---
 .../api/tools/agent-bridge/tproxy/route.ts    |  81 +++++++++++++
 src/mitm/tproxy/caTrust.ts                    | 112 ++++++++++++++++++
 tests/unit/tproxy-ca-trust.test.ts            |  98 +++++++++++++++
 tests/unit/tproxy-route.test.ts               |  68 +++++++++++
 4 files changed, 359 insertions(+)
 create mode 100644 src/app/api/tools/agent-bridge/tproxy/route.ts
 create mode 100644 src/mitm/tproxy/caTrust.ts
 create mode 100644 tests/unit/tproxy-ca-trust.test.ts
 create mode 100644 tests/unit/tproxy-route.test.ts

diff --git a/src/app/api/tools/agent-bridge/tproxy/route.ts b/src/app/api/tools/agent-bridge/tproxy/route.ts
new file mode 100644
index 0000000000..e2130f1f68
--- /dev/null
+++ b/src/app/api/tools/agent-bridge/tproxy/route.ts
@@ -0,0 +1,81 @@
+/**
+ * GET / POST / DELETE /api/tools/agent-bridge/tproxy
+ *
+ * Drive the decrypt-capable TPROXY capture mode (Epic A, decrypt 4b/N):
+ *   - GET    → current status (running / available / interceptCount / onPort)
+ *   - POST   → start: apply the TPROXY rules, open the transparent listener, and
+ *              install the dynamic CA in the OS trust store (dedicated slot)
+ *   - DELETE → stop: close the listener, uninstall the CA, revert the rules
+ *
+ * LOCAL_ONLY: covered by the "/api/tools/agent-bridge/" prefix in routeGuard.ts.
+ * Starting this route applies iptables rules + installs a trust-store CA via
+ * child processes, so loopback-only enforcement (Hard Rules #15 + #17) is
+ * mandatory — a leaked JWT over a tunnel must not be able to reach it.
+ */
+import { z } from "zod";
+import {
+  startCaptureMode,
+  stopCaptureMode,
+  getCaptureStatus,
+} from "@/mitm/tproxy/captureManager";
+import { installTproxyCa, uninstallTproxyCa } from "@/mitm/tproxy/caTrust";
+import { sanitizeErrorMessage } from "@omniroute/open-sse/utils/error";
+import { createErrorResponse } from "@/lib/api/errorResponse";
+
+// Exported for unit testing. Next.js only treats GET/POST/DELETE as route
+// handlers; additional named exports are ignored by the App Router.
+export const StartTproxyBodySchema = z.object({
+  dport: z.number().int().min(1).max(65535).default(443),
+  mark: z.number().int().min(1).default(0x2333),
+  onPort: z.number().int().min(1).max(65535).default(8443),
+  routeTable: z.number().int().min(1).default(233),
+  bypassMark: z.number().int().min(1).default(0x539),
+  // Required on non-root desktops to authorize the trust-store install; ignored
+  // when the process is root (the VPS), where sudo is skipped entirely.
+  sudoPassword: z.string().optional(),
+});
+
+export function GET(): Response {
+  return Response.json(getCaptureStatus());
+}
+
+export async function POST(request: Request): Promise<Response> {
+  const raw = await request.json().catch(() => ({}));
+  const parsed = StartTproxyBodySchema.safeParse(raw);
+  if (!parsed.success) {
+    return createErrorResponse({
+      status: 400,
+      type: "invalid_request",
+      message: "Invalid TPROXY capture config",
+    });
+  }
+
+  const { sudoPassword, ...cfg } = parsed.data;
+  const pwd = sudoPassword ?? "";
+
+  try {
+    const status = await startCaptureMode({
+      cfg,
+      installCa: (caPem) => installTproxyCa(caPem, pwd),
+      uninstallCa: () => uninstallTproxyCa(pwd),
+    });
+    return Response.json({ ok: true, status });
+  } catch (err) {
+    return createErrorResponse({
+      status: 500,
+      message: sanitizeErrorMessage(err instanceof Error ? err.message : String(err)),
+    });
+  }
+}
+
+export async function DELETE(): Promise<Response> {
+  try {
+    const status = await stopCaptureMode();
+    return Response.json({ ok: true, status });
+  } catch (err) {
+    return createErrorResponse({
+      status: 500,
+      message: sanitizeErrorMessage(err instanceof Error ? err.message : String(err)),
+    });
+  }
+}
diff --git a/src/mitm/tproxy/caTrust.ts b/src/mitm/tproxy/caTrust.ts
new file mode 100644
index 0000000000..7d1cea8655
--- /dev/null
+++ b/src/mitm/tproxy/caTrust.ts
@@ -0,0 +1,112 @@
+/**
+ * Fase 3 / Epic A — OS trust-store install for the TPROXY dynamic CA (decrypt 4b/N).
+ *
+ * The decrypt capture mode issues per-SNI leaves from a dynamic CA (#4173); the
+ * intercepted clients must trust that CA. This installs the CA cert into the OS
+ * trust store under a DEDICATED slot (`omniroute-tproxy-ca.crt`), separate from
+ * the static MITM cert (`omniroute-mitm.crt` in `cert/install.ts`), so the two
+ * never clobber each other.
+ *
+ * Linux-only (TPROXY is Linux-only). Privileged commands run via the controlled
+ * `execFileWithPassword` helper — `spawn` with arg arrays, no shell, no string
+ * interpolation (Hard Rule #13). It already runs the target directly (no `sudo`)
+ * when the process is root, so on the VPS no password is needed. Every effectful
+ * seam is injectable so the command sequence is unit-testable without root.
+ */
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+import { execFileWithPassword } from "../systemCommands.ts";
+
+/** Dedicated trust-store filename — distinct from the static MITM cert's slot. */
+export const TPROXY_CA_CERT_NAME = "omniroute-tproxy-ca.crt";
+
+/** Trust-store anchor dirs + refresh command, in detection order (Debian first). */
+const LINUX_CERT_PATHS: ReadonlyArray<{ dir: string; cmd: string }> = [
+  { dir: "/usr/local/share/ca-certificates", cmd: "update-ca-certificates" },
+  { dir: "/etc/ca-certificates/trust-source/anchors", cmd: "update-ca-trust" },
+  { dir: "/etc/pki/ca-trust/source/anchors", cmd: "update-ca-trust" },
+  { dir: "/etc/pki/trust/anchors", cmd: "update-ca-certificates" },
+];
+
+export type SudoRunner = (command: string, args: string[], password: string) => Promise<unknown>;
+
+export interface CaTrustDeps {
+  /** Run a privileged command (sudo/arg-array; runs direct when root). */
+  run: SudoRunner;
+  /** Stage the CA PEM to a local file before the privileged copy. */
+  writeFile: (filePath: string, data: string) => void;
+  /** Remove the staged file (best-effort). */
+  rmFile: (filePath: string) => void;
+  /** Directory to stage the PEM in. */
+  tmpDir: () => string;
+  /** Resolve the trust-store anchor dir + refresh command for this distro. */
+  certConfig: () => { dir: string; cmd: string };
+  /** Host platform (Linux-only gate). */
+  platform: () => string;
+}
+
+function detectCertConfig(): { dir: string; cmd: string } {
+  for (const c of LINUX_CERT_PATHS) {
+    if (fs.existsSync(c.dir)) return c;
+  }
+  return LINUX_CERT_PATHS[0];
+}
+
+const realDeps: CaTrustDeps = {
+  run: execFileWithPassword,
+  writeFile: (filePath, data) => fs.writeFileSync(filePath, data, { mode: 0o644 }),
+  rmFile: (filePath) => {
+    try {
+      fs.unlinkSync(filePath);
+    } catch {
+      // best-effort cleanup
+    }
+  },
+  tmpDir: () => os.tmpdir(),
+  certConfig: detectCertConfig,
+  platform: () => process.platform,
+};
+
+/**
+ * Install the dynamic CA cert (PEM) into the OS trust store under the dedicated
+ * TPROXY slot. Stages the PEM to a temp file, then (privileged) copies it into the
+ * anchor dir and refreshes the trust store. Throws on non-Linux hosts.
+ */
+export async function installTproxyCa(
+  caPem: string,
+  sudoPassword = "",
+  deps: Partial<CaTrustDeps> = {}
+): Promise<void> {
+  const d = { ...realDeps, ...deps };
+  if (d.platform() !== "linux") {
+    throw new Error("TPROXY CA trust install is Linux-only.");
+  }
+  const cfg = d.certConfig();
+  const staged = path.join(d.tmpDir(), TPROXY_CA_CERT_NAME);
+  const dest = `${cfg.dir}/${TPROXY_CA_CERT_NAME}`;
+  d.writeFile(staged, caPem);
+  try {
+    await d.run("sudo", ["-S", "mkdir", "-p", cfg.dir], sudoPassword);
+    await d.run("sudo", ["-S", "cp", staged, dest], sudoPassword);
+    await d.run("sudo", ["-S", cfg.cmd], sudoPassword);
+  } finally {
+    d.rmFile(staged);
+  }
+}
+
+/**
+ * Remove the TPROXY CA from the OS trust store (its dedicated slot only — leaves
+ * the static MITM cert untouched) and refresh. No-op on non-Linux hosts.
+ */
+export async function uninstallTproxyCa(
+  sudoPassword = "",
+  deps: Partial<CaTrustDeps> = {}
+): Promise<void> {
+  const d = { ...realDeps, ...deps };
+  if (d.platform() !== "linux") return;
+  const cfg = d.certConfig();
+  const dest = `${cfg.dir}/${TPROXY_CA_CERT_NAME}`;
+  await d.run("sudo", ["-S", "rm", "-f", dest], sudoPassword);
+  await d.run("sudo", ["-S", cfg.cmd], sudoPassword);
+}
diff --git a/tests/unit/tproxy-ca-trust.test.ts b/tests/unit/tproxy-ca-trust.test.ts
new file mode 100644
index 0000000000..14d39d90ba
--- /dev/null
+++ b/tests/unit/tproxy-ca-trust.test.ts
@@ -0,0 +1,98 @@
+/**
+ * Fase 3 / Epic A — OS trust-store install for the TPROXY dynamic CA (decrypt 4b/N).
+ *
+ * Installs the dynamic CA into the trust store under a DEDICATED slot
+ * (`omniroute-tproxy-ca.crt`) so it never clobbers the static MITM cert slot.
+ * Every effectful seam is injected, so these tests pin the exact privileged
+ * command sequence (no shell, arg arrays — Hard Rule #13) without root.
+ */
+import test from "node:test";
+import assert from "node:assert/strict";
+import {
+  installTproxyCa,
+  uninstallTproxyCa,
+  TPROXY_CA_CERT_NAME,
+} from "../../src/mitm/tproxy/caTrust.ts";
+
+function fakeDeps(over: Record<string, unknown> = {}) {
+  const calls: Array<{ command: string; args: string[] }> = [];
+  const writes: Array<{ path: string; data: string }> = [];
+  const removed: string[] = [];
+  return {
+    calls,
+    writes,
+    removed,
+    deps: {
+      run: async (command: string, args: string[]) => {
+        calls.push({ command, args });
+      },
+      writeFile: (p: string, data: string) => {
+        writes.push({ path: p, data });
+      },
+      rmFile: (p: string) => {
+        removed.push(p);
+      },
+      tmpDir: () => "/tmp",
+      certConfig: () => ({ dir: "/usr/local/share/ca-certificates", cmd: "update-ca-certificates" }),
+      platform: () => "linux",
+      ...over,
+    } as never,
+  };
+}
+
+test("installTproxyCa stages the PEM, copies it into the dedicated slot, refreshes, cleans up", async () => {
+  const f = fakeDeps();
+  await installTproxyCa("CA-PEM", "", f.deps);
+
+  assert.equal(f.writes.length, 1);
+  assert.match(f.writes[0].path, /omniroute-tproxy-ca\.crt$/);
+  assert.equal(f.writes[0].data, "CA-PEM");
+
+  const cmds = f.calls.map((c) => `${c.command} ${c.args.join(" ")}`);
+  assert.deepEqual(cmds, [
+    "sudo -S mkdir -p /usr/local/share/ca-certificates",
+    `sudo -S cp /tmp/${TPROXY_CA_CERT_NAME} /usr/local/share/ca-certificates/${TPROXY_CA_CERT_NAME}`,
+    "sudo -S update-ca-certificates",
+  ]);
+  assert.deepEqual(f.removed, [`/tmp/${TPROXY_CA_CERT_NAME}`], "staged file cleaned up");
+});
+
+test("installTproxyCa never touches the static MITM cert slot", async () => {
+  const f = fakeDeps();
+  await installTproxyCa("CA-PEM", "", f.deps);
+  const joined = f.calls.map((c) => c.args.join(" ")).join(" ");
+  assert.ok(!joined.includes("omniroute-mitm.crt"), "must not collide with the MITM cert");
+  assert.ok(joined.includes("omniroute-tproxy-ca.crt"));
+});
+
+test("installTproxyCa cleans up the staged file even when a privileged command fails", async () => {
+  const f = fakeDeps({
+    run: async (_c: string, a: string[]) => {
+      if (a.includes("cp")) throw new Error("EPERM: not permitted");
+    },
+  });
+  await assert.rejects(() => installTproxyCa("CA-PEM", "", f.deps), /EPERM/);
+  assert.deepEqual(f.removed, [`/tmp/${TPROXY_CA_CERT_NAME}`], "staged file still cleaned up on failure");
+});
+
+test("installTproxyCa throws on non-Linux hosts and runs nothing", async () => {
+  const f = fakeDeps({ platform: () => "darwin" });
+  await assert.rejects(() => installTproxyCa("CA-PEM", "", f.deps), /Linux-only/);
+  assert.equal(f.calls.length, 0);
+});
+
+test("uninstallTproxyCa removes only the dedicated slot and refreshes", async () => {
+  const f = fakeDeps();
+  await uninstallTproxyCa("", f.deps);
+  const cmds = f.calls.map((c) => `${c.command} ${c.args.join(" ")}`);
+  assert.deepEqual(cmds, [
+    `sudo -S rm -f /usr/local/share/ca-certificates/${TPROXY_CA_CERT_NAME}`,
+    "sudo -S update-ca-certificates",
+  ]);
+});
+
+test("uninstallTproxyCa is a no-op on non-Linux hosts", async () => {
+  const f = fakeDeps({ platform: () => "win32" });
+  await uninstallTproxyCa("", f.deps);
+  assert.equal(f.calls.length, 0);
+});
diff --git a/tests/unit/tproxy-route.test.ts b/tests/unit/tproxy-route.test.ts
new file mode 100644
index 0000000000..f834799d63
--- /dev/null
+++ b/tests/unit/tproxy-route.test.ts
@@ -0,0 +1,68 @@
+/**
+ * Fase 3 / Epic A — /api/tools/agent-bridge/tproxy route (decrypt 4b/N).
+ *
+ * Drives the decrypt capture mode (start/stop/status). The route applies iptables
+ * rules + installs a trust-store CA via child processes, so it MUST be local-only
+ * (Hard Rules #15 + #17). In CI the native addon is absent, so start fails
+ * gracefully with a sanitized 500 — which is exactly what these tests pin, along
+ * with config validation, status, and the local-only classification.
+ */
+import test from "node:test";
+import assert from "node:assert/strict";
+import {
+  GET,
+  POST,
+  DELETE,
+  StartTproxyBodySchema,
+} from "../../src/app/api/tools/agent-bridge/tproxy/route.ts";
+import { isLocalOnlyPath } from "../../src/server/authz/routeGuard.ts";
+
+function postReq(body: unknown): Request {
+  return new Request("http://local/api/tools/agent-bridge/tproxy", {
+    method: "POST",
+    body: JSON.stringify(body),
+  });
+}
+
+test("the tproxy route is classified LOCAL_ONLY (spawns iptables + installs a CA)", () => {
+  assert.equal(isLocalOnlyPath("/api/tools/agent-bridge/tproxy"), true);
+});
+
+test("GET reports running:false and an available boolean when idle", async () => {
+  const res = GET();
+  assert.equal(res.status, 200);
+  const body = await res.json();
+  assert.equal(body.running, false);
+  assert.equal(typeof body.available, "boolean");
+});
+
+test("POST rejects an out-of-range config with a 400 invalid_request", async () => {
+  const res = await POST(postReq({ dport: 70000 }));
+  assert.equal(res.status, 400);
+  const body = await res.json();
+  assert.equal(body.error.type, "invalid_request");
+});
+
+test("POST returns a sanitized 500 when the native addon is unavailable (CI)", async () => {
+  const res = await POST(postReq({}));
+  assert.equal(res.status, 500);
+  const body = await res.json();
+  assert.match(body.error.message, /native addon|CAP_NET_ADMIN/);
+  assert.ok(!body.error.message.includes("at /"), "no stack trace leaked");
+});
+
+test("DELETE stops (no-op when idle) and returns ok with status", async () => {
+  const res = await DELETE();
+  assert.equal(res.status, 200);
+  const body = await res.json();
+  assert.equal(body.ok, true);
+  assert.equal(body.status.running, false);
+});
+
+test("StartTproxyBodySchema applies sensible TPROXY defaults", () => {
+  const parsed = StartTproxyBodySchema.parse({});
+  assert.equal(parsed.dport, 443);
+  assert.equal(parsed.onPort, 8443);
+  assert.equal(parsed.routeTable, 233);
+  assert.equal(parsed.bypassMark, 0x539);
+});