fix(auth): fail closed configuration compatibility

backend/src/auth/auth.ts

@@ -1,12 +1,11 @@
 import type { FastifyRequest, FastifyReply } from "fastify";
 import { localPrincipal, type PrincipalContext, upstreamPrincipal } from "./principal.js";
-import type { AuthMode } from "./types.js";
 
 declare module "fastify" {
   interface FastifyRequest { principal?: PrincipalContext }
 }
 
-export function authPreHandler(mode: AuthMode) {
+export function authPreHandler(mode: "none" | "mock" | "upstream") {
   return async (req: FastifyRequest, reply: FastifyReply) => {
     if (mode === "none") {
       req.principal = localPrincipal();

backend/src/auth/config.ts

@@ -59,7 +59,9 @@ const oidcSchema = z.strictObject({
   authorization: z.strictObject({ groupRoles: groupRolesSchema }),
 });
 
-function readBoundedConfig(path: string): string {
+interface FileIdentity { dev: number; ino: number; size: number; mtimeMs: number }
+
+function readBoundedConfig(path: string): { source: string; identity: FileIdentity } {
   let fd: number | undefined;
   try {
     fd = openSync(path, constants.O_RDONLY | constants.O_NOFOLLOW);
@@ -68,7 +70,10 @@ function readBoundedConfig(path: string): string {
     const buffer = Buffer.allocUnsafe(MAX_AUTH_CONFIG_BYTES + 1);
     const bytesRead = readSync(fd, buffer, 0, buffer.length, 0);
     if (bytesRead > MAX_AUTH_CONFIG_BYTES) throw invalid();
-    return new TextDecoder("utf-8", { fatal: true }).decode(buffer.subarray(0, bytesRead));
+    return {
+      source: new TextDecoder("utf-8", { fatal: true }).decode(buffer.subarray(0, bytesRead)),
+      identity: { dev: info.dev, ino: info.ino, size: info.size, mtimeMs: info.mtimeMs },
+    };
   } catch {
     throw invalid();
   } finally {
@@ -105,7 +110,7 @@ function canonicalize(value: unknown): unknown {
   if (Array.isArray(value)) return value.map(canonicalize);
   if (value && typeof value === "object") {
     return Object.fromEntries(Object.entries(value as Record<string, unknown>)
-      .sort(([left], [right]) => left.localeCompare(right))
+      .sort(([left], [right]) => left < right ? -1 : left > right ? 1 : 0)
       .map(([key, nested]) => [key, canonicalize(nested)]));
   }
   return value;
@@ -139,13 +144,16 @@ function parseAuthenticationConfig(source: string): AuthenticationConfig {
   } catch { throw invalid(); }
 }
 
-export function loadAuthenticationConfig(path: string): LoadedAuthConfig {
+function loadAuthenticationConfigWithIdentity(path: string): { loaded: LoadedAuthConfig; identity: FileIdentity } {
   if (typeof path !== "string" || path.length === 0 || path.trim() !== path || path.includes("\0")) throw invalid();
-  const value = parseAuthenticationConfig(readBoundedConfig(path));
-  return { value, revision: canonicalRevision(value), sourcePath: path };
+  const read = readBoundedConfig(path);
+  const value = parseAuthenticationConfig(read.source);
+  return { loaded: { value, revision: canonicalRevision(value), sourcePath: path }, identity: read.identity };
 }
 
-interface FileIdentity { dev: number; ino: number; size: number; mtimeMs: number }
+export function loadAuthenticationConfig(path: string): LoadedAuthConfig {
+  return loadAuthenticationConfigWithIdentity(path).loaded;
+}
 
 function fileIdentity(path: string): FileIdentity {
   try {
@@ -164,9 +172,14 @@ export function createAuthenticationConfigProvider(path: string): Authentication
   return { current(): LoadedAuthConfig {
     const before = fileIdentity(path);
     if (cached && sameIdentity(cached.identity, before)) return cached.loaded;
-    const loaded = loadAuthenticationConfig(path);
-    cached = { identity: fileIdentity(path), loaded };
-    return loaded;
+    for (let attempt = 0; attempt < 2; attempt += 1) {
+      const { loaded, identity } = loadAuthenticationConfigWithIdentity(path);
+      if (sameIdentity(identity, fileIdentity(path))) {
+        cached = { identity, loaded };
+        return loaded;
+      }
+    }
+    throw invalid();
   } };
 }