Harden cookie authentication

server/api/auth/register.post.ts

@@ -1,10 +1,15 @@
 import { readBody, setCookie, setResponseStatus } from "h3"
 import argon2 from "argon2"
 import { User } from "../../models/user"
-import { REFRESH_COOKIE } from "../../utils/auth"
+import {
+	assertCookieRequestOrigin,
+	defineAuthenticatedEventHandler,
+	REFRESH_COOKIE,
+} from "../../utils/auth"
 import { getAuthValidationMessage } from "../../utils/auth-validation"
 
-export default defineEventHandler(async (event) => {
+export default defineAuthenticatedEventHandler(async (event) => {
+	assertCookieRequestOrigin(event)
 	const body = await readBody(event)
 	const validationMessage = getAuthValidationMessage(body, [
 		{ name: "name" },

server/api/auth/session.post.ts

@@ -2,13 +2,15 @@ import { getCookie, readBody, setCookie, setResponseStatus } from "h3"
 import { User } from "../../models/user"
 import { getSessionModel } from "../../models/session"
 import {
+	assertCookieRequestOrigin,
+	defineAuthenticatedEventHandler,
 	getSessionTtl,
 	REFRESH_COOKIE,
 	SESSION_COOKIE,
 } from "../../utils/auth"
 import { getAuthValidationMessage } from "../../utils/auth-validation"
 
-export default defineEventHandler(async (event) => {
+export default defineAuthenticatedEventHandler(async (event) => {
 	const body = await readBody(event).catch(() => undefined)
 	const validationMessage =
 		body === undefined ? null : getAuthValidationMessage(body, [{ name: "refreshToken" }])
@@ -17,9 +19,10 @@ export default defineEventHandler(async (event) => {
 		return { message: validationMessage }
 	}
 
-	const refreshToken =
-		(typeof body?.refreshToken === "string" && body.refreshToken) ||
-		getCookie(event, REFRESH_COOKIE)
+	const bodyRefreshToken = typeof body?.refreshToken === "string" && body.refreshToken
+	const cookieRefreshToken = getCookie(event, REFRESH_COOKIE)
+	if (!bodyRefreshToken && cookieRefreshToken) assertCookieRequestOrigin(event)
+	const refreshToken = bodyRefreshToken || cookieRefreshToken
 
 	if (!refreshToken) {
 		setResponseStatus(event, 401)

server/api/auth/signin.post.ts

@@ -1,10 +1,15 @@
 import { readBody, setCookie, setResponseStatus } from "h3"
 import argon2 from "argon2"
 import { User } from "../../models/user"
-import { REFRESH_COOKIE } from "../../utils/auth"
+import {
+	assertCookieRequestOrigin,
+	defineAuthenticatedEventHandler,
+	REFRESH_COOKIE,
+} from "../../utils/auth"
 import { getAuthValidationMessage } from "../../utils/auth-validation"
 
-export default defineEventHandler(async (event) => {
+export default defineAuthenticatedEventHandler(async (event) => {
+	assertCookieRequestOrigin(event)
 	const body = await readBody(event)
 	const validationMessage = getAuthValidationMessage(body, [
 		{ name: "email", email: true },

server/api/auth/signout.post.ts

@@ -1,7 +1,13 @@
 import { deleteCookie } from "h3"
-import { REFRESH_COOKIE, SESSION_COOKIE } from "../../utils/auth"
+import {
+	assertCookieRequestOrigin,
+	defineAuthenticatedEventHandler,
+	REFRESH_COOKIE,
+	SESSION_COOKIE,
+} from "../../utils/auth"
 
-export default defineEventHandler((event) => {
+export default defineAuthenticatedEventHandler((event) => {
+	assertCookieRequestOrigin(event)
 	deleteCookie(event, REFRESH_COOKIE, { path: "/", sameSite: "lax", secure: !import.meta.dev })
 	deleteCookie(event, SESSION_COOKIE, { path: "/", sameSite: "lax", secure: !import.meta.dev })
 	return { success: true }

server/utils/auth.ts

@@ -1,5 +1,13 @@
 import type { H3Event } from "h3"
-import { createError, getCookie } from "h3"
+import {
+	createError,
+	defineEventHandler,
+	getCookie,
+	getRequestHeader,
+	getRequestURL,
+	setResponseStatus,
+	type EventHandler,
+} from "h3"
 import parseDuration from "parse-duration"
 import mongoose from "mongoose"
 import { getSessionModel } from "../models/session"
@@ -7,6 +15,64 @@ import { getBackendRuntimeConfig } from "./backend-config"
 
 export const SESSION_COOKIE = "musicSession"
 export const REFRESH_COOKIE = "refreshToken"
+const INVALID_REQUEST_ORIGIN = "Invalid request origin"
+
+/**
+ * Keep the legacy API's direct authentication response body while leaving all
+ * unrelated H3 errors to Nitro's normal error handler.
+ */
+export function defineAuthenticatedEventHandler(handler: EventHandler) {
+	return defineEventHandler(async (event) => {
+		try {
+			return await handler(event)
+		} catch (error) {
+			const statusCode = (error as { statusCode?: number } | undefined)?.statusCode
+			const statusMessage = (error as { statusMessage?: string } | undefined)?.statusMessage
+			const message = (error as { data?: { message?: string } } | undefined)?.data?.message
+
+			if (statusCode === 401 && statusMessage === "Unauthorized" && message === "Unauthorized") {
+				setResponseStatus(event, 401)
+				return { message: "Unauthorized" }
+			}
+
+			if (statusCode === 403 && statusMessage === "Forbidden" && message === INVALID_REQUEST_ORIGIN) {
+				setResponseStatus(event, 403)
+				return { message: INVALID_REQUEST_ORIGIN }
+			}
+
+			throw error
+		}
+	})
+}
+
+export function assertCookieRequestOrigin(event: H3Event) {
+	const originHeader = getRequestHeader(event, "origin")
+	const refererHeader = getRequestHeader(event, "referer")
+	let requestOrigin: string | undefined
+	let suppliedOrigin: string | undefined
+
+	try {
+		// H3 uses Host for the request host. A trusted ingress may provide
+		// x-forwarded-proto; it must overwrite that header before this app.
+		requestOrigin = getRequestURL(event, { xForwardedProto: true }).origin
+		if (originHeader !== undefined) {
+			const parsedOrigin = new URL(originHeader)
+			if (parsedOrigin.origin === originHeader) suppliedOrigin = parsedOrigin.origin
+		} else if (refererHeader !== undefined) {
+			suppliedOrigin = new URL(refererHeader).origin
+		}
+	} catch {
+		// Invalid or absent browser origin proof is rejected below.
+	}
+
+	if (!suppliedOrigin || !requestOrigin || suppliedOrigin !== requestOrigin) {
+		throw createError({
+			statusCode: 403,
+			statusMessage: "Forbidden",
+			data: { message: INVALID_REQUEST_ORIGIN },
+		})
+	}
+}
 
 export function getSessionTtl(event?: H3Event) {
 	const { tokenExpire } = getBackendRuntimeConfig(event)
@@ -14,15 +80,17 @@ export function getSessionTtl(event?: H3Event) {
 }
 
 function getSessionTokens(event: H3Event) {
-	const tokens: string[] = []
+	const tokens: { token: string; source: "cookie" | "bearer" }[] = []
 	const cookieToken = getCookie(event, SESSION_COOKIE)
 	const authorization = event.node.req.headers.authorization
 	const bearerToken = authorization?.startsWith("Bearer ")
 		? authorization.slice("Bearer ".length)
 		: undefined
 
-	if (cookieToken) tokens.push(cookieToken)
-	if (bearerToken && bearerToken !== cookieToken) tokens.push(bearerToken)
+	if (cookieToken) tokens.push({ token: cookieToken, source: "cookie" })
+	if (bearerToken && bearerToken !== cookieToken) {
+		tokens.push({ token: bearerToken, source: "bearer" })
+	}
 
 	return tokens
 }
@@ -30,8 +98,8 @@ function getSessionTokens(event: H3Event) {
 export async function findSession(event: H3Event) {
 	const Session = getSessionModel(getSessionTtl(event)) as mongoose.Model<any>
 
-	for (const token of getSessionTokens(event)) {
-		const session = await Session.findOne({ token })
+	for (const credential of getSessionTokens(event)) {
+		const session = await Session.findOne({ token: credential.token })
 			.populate("userId", "+verified")
 			.exec()
 
@@ -41,7 +109,13 @@ export async function findSession(event: H3Event) {
 
 		if (!session || !user) continue
 
-		return { session, user }
+		const bearerToken = event.node.req.headers.authorization?.startsWith("Bearer ")
+			? event.node.req.headers.authorization.slice("Bearer ".length)
+			: undefined
+		// If the cookie and bearer header carry the same valid token, the request
+		// is independently authenticated by the explicit bearer credential.
+		const source = bearerToken === credential.token ? "bearer" : credential.source
+		return { session, user, source }
 	}
 
 	return null
@@ -63,5 +137,11 @@ export async function requireAuthenticatedUser(event: H3Event, adminOnly = false
 		})
 	}
 
+	const method = event.node.req.method?.toUpperCase() || "GET"
+	const isUnsafeMethod = !["GET", "HEAD", "OPTIONS"].includes(method)
+	if (isUnsafeMethod && auth.source === "cookie") {
+		assertCookieRequestOrigin(event)
+	}
+
 	return auth.user
 }