fix(sdk,openapi): block SSRF targets when fetching integration specs by URL

Author: pt-act

.changeset/egress-guard.md

@@ -0,0 +1,21 @@
+---
+"@executor-js/sdk": patch
+"@executor-js/plugin-openapi": patch
+---
+
+fix: block SSRF targets when fetching integration specs by URL
+
+Adding an OpenAPI (or other URL-based) integration fetched the spec URL
+server-side with no egress filtering. A crafted URL pointing at cloud
+metadata (169.254.169.254), loopback, RFC1918, or link-local addresses let
+the fetch feature reach internal state on hosted deployments.
+
+A shared egress guard (`assertFetchable`) now validates every spec-fetch
+target before connecting: it normalizes DNS-encoding tricks (decimal/octal/
+hex integer IPv4, trailing dots), resolves hostnames, and fails closed if
+any resolved address is loopback, RFC1918, link-local, carrier-grade NAT,
+IPv6 link-local/ULA, or IPv4-mapped private. The resolved address is pinned
+for the connect (no second resolution, so DNS rebinding cannot swap in a
+private target), and the original host is preserved in the Host header.
+Rejections are coarse ("blocked by egress policy") and never echo internal
+addresses.

e2e/setup/cloud.globalsetup.ts

@@ -32,6 +32,10 @@ const optionalCloudEnv = (): Record<string, string> => {
   const env: Record<string, string> = {
     SENTRY_OTEL_VERIFY: "true",
     SENTRY_OTEL_LOG_PAYLOAD: "true",
+    // The e2e cloud stack serves integration specs from a loopback fixture
+    // server — the egress guard's loopback block must be explicitly trusted
+    // here. Production never sets this.
+    EXECUTOR_ALLOW_LOOPBACK_SPECS: "1",
     // Boot the BROWSER crash reporter too, so what the frontend actually
     // reports is observable to a scenario. Production always has this set;
     // without it the reporter the app wires into ExecutorProvider is a no-op

packages/core/sdk/src/egress.test.ts

@@ -0,0 +1,131 @@
+import { describe, expect, it } from "@effect/vitest";
+import { Effect } from "effect";
+
+import { assertFetchable, isBlockedAddress } from "./egress";
+
+// ---------------------------------------------------------------------------
+// Focused tests — egress-guard classification boundaries and the pinned
+// resolve/connect contract.
+//
+// assertFetchable is pure (DNS injected as a lookup fn), so these tests need
+// no executor harness, no DB, no scope. Encoded-host permutations and
+// redirect-chain behavior are covered by property tests elsewhere; these
+// pin the classification boundaries and the pin-return contract.
+// ---------------------------------------------------------------------------
+
+const publicLookup = async (hostname: string): Promise<string[]> =>
+  hostname === "petstore3.swagger.io" ? ["104.18.16.10"] : ["93.184.216.34"];
+
+const run = (url: string, lookup = publicLookup) => Effect.runPromise(assertFetchable(url, lookup));
+
+describe("isBlockedAddress (pure classification)", () => {
+  it("blocks metadata, loopback, RFC1918, CGNAT, link-local", () => {
+    expect(isBlockedAddress("169.254.169.254")).toBe(true); // cloud metadata
+    expect(isBlockedAddress("127.0.0.1")).toBe(true);
+    expect(isBlockedAddress("10.0.0.1")).toBe(true);
+    expect(isBlockedAddress("192.168.1.1")).toBe(true);
+    expect(isBlockedAddress("172.16.0.1")).toBe(true);
+    expect(isBlockedAddress("100.64.0.1")).toBe(true); // CGNAT
+    expect(isBlockedAddress("0.0.0.0")).toBe(true);
+  });
+
+  it("allows public addresses", () => {
+    expect(isBlockedAddress("8.8.8.8")).toBe(false);
+    expect(isBlockedAddress("104.18.16.10")).toBe(false);
+    expect(isBlockedAddress("93.184.216.34")).toBe(false);
+  });
+
+  it("blocks IPv6 loopback, link-local, ULA, and IPv4-mapped private", () => {
+    expect(isBlockedAddress("::1")).toBe(true);
+    expect(isBlockedAddress("fe80::1")).toBe(true);
+    expect(isBlockedAddress("fc00::1")).toBe(true);
+    expect(isBlockedAddress("fd00::1")).toBe(true);
+    expect(isBlockedAddress("::ffff:127.0.0.1")).toBe(true); // mapped loopback
+    expect(isBlockedAddress("::ffff:169.254.169.254")).toBe(true); // mapped metadata
+  });
+
+  it("fails closed on unparseable input", () => {
+    expect(isBlockedAddress("not-an-ip")).toBe(true);
+    expect(isBlockedAddress("")).toBe(true);
+  });
+});
+
+describe("assertFetchable (allowLoopback trust mode)", () => {
+  it("allows a loopback literal when the option is set", async () => {
+    const pinned = await Effect.runPromise(
+      assertFetchable("http://127.0.0.1:8787/spec.json", { allowLoopback: true }),
+    );
+    expect(pinned.resolvedAddress).toBe("127.0.0.1");
+  });
+
+  it("passes the hostname through when the resolver yields nothing (trusted resolver)", async () => {
+    const emptyLookup = async (): Promise<string[]> => [];
+    const pinned = await Effect.runPromise(
+      assertFetchable("http://fixture.local:8787/spec.json", emptyLookup, { allowLoopback: true }),
+    );
+    expect(pinned.hostname).toBe("fixture.local");
+    expect(pinned.resolvedAddress).toBe("fixture.local");
+  });
+
+  it("still blocks an unresolvable hostname without the option (fail closed)", async () => {
+    const emptyLookup = async (): Promise<string[]> => [];
+    await expect(
+      Effect.runPromise(assertFetchable("http://fixture.local:8787/spec.json", emptyLookup)),
+    ).rejects.toMatchObject({ _tag: "EgressError" });
+  });
+});
+
+describe("assertFetchable (resolve + classify + pin)", () => {
+  it("accepts a public hostname and returns the pinned resolved address", async () => {
+    const pinned = await run("https://petstore3.swagger.io/api/v3/openapi.json");
+    expect(pinned.hostname).toBe("petstore3.swagger.io");
+    expect(pinned.resolvedAddress).toBe("104.18.16.10");
+    expect(pinned.url).toBe("https://petstore3.swagger.io/api/v3/openapi.json");
+  });
+
+  it("rejects a metadata literal without DNS (fail closed)", async () => {
+    await expect(run("http://169.254.169.254/latest/meta-data/")).rejects.toMatchObject({
+      _tag: "EgressError",
+    });
+  });
+
+  it("rejects a decimal-encoded metadata IP (2852039166 = 169.254.169.254)", async () => {
+    await expect(run("http://2852039166/latest/meta-data/")).rejects.toMatchObject({
+      _tag: "EgressError",
+    });
+  });
+
+  it("rejects a hex-encoded loopback (0x7f000001 = 127.0.0.1)", async () => {
+    await expect(run("http://0x7f000001/")).rejects.toMatchObject({
+      _tag: "EgressError",
+    });
+  });
+
+  it("rejects an octal-encoded loopback (0177.0.0.1 = 127.0.0.1)", async () => {
+    await expect(run("http://0177.0.0.1/")).rejects.toMatchObject({
+      _tag: "EgressError",
+    });
+  });
+
+  it("rejects a hostname that resolves to a private address (DNS-pinned check)", async () => {
+    const privateResolvingLookup = async (): Promise<string[]> => ["10.0.0.5"];
+    await expect(run("http://evil.example.com/", privateResolvingLookup)).rejects.toMatchObject({
+      _tag: "EgressError",
+    });
+  });
+
+  it("rejects a hostname that resolves to ANY private address among public ones", async () => {
+    const mixedLookup = async (): Promise<string[]> => ["104.18.16.10", "169.254.169.254"];
+    await expect(run("http://evil.example.com/", mixedLookup)).rejects.toMatchObject({
+      _tag: "EgressError",
+    });
+  });
+
+  it("rejects non-http(s) schemes and userinfo", async () => {
+    await expect(run("file:///etc/passwd")).rejects.toMatchObject({ _tag: "EgressError" });
+    await expect(run("ftp://example.com/")).rejects.toMatchObject({ _tag: "EgressError" });
+    await expect(run("http://user:pass@example.com/")).rejects.toMatchObject({
+      _tag: "EgressError",
+    });
+  });
+});