Add WebAuthn authentication flow

edb/lib/ext/auth.edgeql

@@ -68,16 +68,24 @@ CREATE EXTENSION PACKAGE auth VERSION '1.0' {
     };
 
     create type ext::auth::WebAuthnFactor extending ext::auth::EmailFactor {
-        create required property user_handle: std::bytes {
-            create constraint exclusive;
-        };
+        create required property user_handle: std::bytes;
         create required property credential_id: std::bytes {
             create constraint exclusive;
         };
         create required property public_key: std::bytes {
             create constraint exclusive;
         };
 
+        create trigger email_shares_user_handle after insert for each do (
+            std::assert(
+                (__new__.user_handle = (
+                    select detached ext::auth::WebAuthnFactor
+                    filter .email = __new__.email
+                    and not .id = __new__.id
+                ).user_handle) ?? true,
+                message := "user_handle must be the same for a given email"
+            )
+        );
         create constraint exclusive on ((.email, .credential_id));
     };
 
@@ -92,6 +100,16 @@ CREATE EXTENSION PACKAGE auth VERSION '1.0' {
         create constraint exclusive on ((.user_handle, .email, .challenge));
     };
 
+    create type ext::auth::WebAuthnAuthenticationChallenge
+        extending ext::auth::Auditable {
+        create required property challenge: std::bytes {
+            create constraint exclusive;
+        };
+        create required link factor: ext::auth::WebAuthnFactor {
+            create constraint exclusive;
+        };
+    };
+
     create type ext::auth::PKCEChallenge extending ext::auth::Auditable {
         create required property challenge: std::str {
             create constraint exclusive;

edb/server/protocol/auth_ext/_static/utils.js

@@ -21,3 +21,35 @@ export function encodeBase64Url(bytes) {
     .replace(/\//g, "_")
     .replace(/=/g, "");
 }
+
+/**
+ * Parse an HTTP Response object. Allows passing in custom handlers for
+ * different status codes and error.type values
+ *
+ * @param {Response} response
+ * @param {Function[]=} handlers
+ */
+export async function parseResponseAsJSON(response, handlers = []) {
+  const bodyText = await response.text();
+
+  if (!response.ok) {
+    let error;
+    try {
+      error = JSON.parse(bodyText);
+    } catch (e) {
+      throw new Error(
+        `Failed to parse body as JSON. Status: ${response.status} ${response.statusText}. Body: ${bodyText}`
+      );
+    }
+
+    for (const handler of handlers) {
+      handler(response, error);
+    }
+
+    throw new Error(
+      `Response was not OK. Status: ${response.status} ${response.statusText}. Body: ${bodyText}`
+    );
+  }
+
+  return response.json();
+}

edb/server/protocol/auth_ext/_static/webauthn-authenticate.js

@@ -0,0 +1,202 @@
+import {
+  decodeBase64Url,
+  encodeBase64Url,
+  parseResponseAsJSON,
+} from "./utils.js";
+
+document.addEventListener("DOMContentLoaded", () => {
+  /** @type {HTMLFormElement | null} */
+  const authenticateForm = document.getElementById("email-factor");
+
+  if (authenticateForm === null) {
+    return;
+  }
+
+  authenticateForm.addEventListener("submit", async (event) => {
+    if (event.submitter?.id !== "webauthn-signin") {
+      return;
+    }
+    event.preventDefault();
+
+    const formData = new FormData(
+      /** @type {HTMLFormElement} */ authenticateForm
+    );
+    const email = formData.get("email");
+    const provider = "builtin::local_webauthn";
+    const challenge = formData.get("challenge");
+    const redirectOnFailure = formData.get("redirect_on_failure");
+    const redirectTo = formData.get("redirect_to");
+
+    if (redirectTo === null) {
+      throw new Error("Missing redirect_to parameter");
+    }
+
+    try {
+      const maybeCode = await authenticate({
+        email,
+        provider,
+        challenge,
+      });
+
+      const redirectUrl = new URL(redirectTo);
+      if (maybeCode !== null) {
+        redirectUrl.searchParams.append("code", maybeCode);
+      }
+
+      window.location.href = redirectUrl.href;
+    } catch (error) {
+      console.error("Failed to register WebAuthn credentials:", error);
+      const url = new URL(redirectOnFailure ?? redirectTo);
+      url.searchParams.append("error", error.message);
+      window.location.href = url.href;
+    }
+  });
+});
+
+const WEBAUTHN_OPTIONS_URL = new URL(
+  "../webauthn/authenticate/options",
+  window.location
+);
+const WEBAUTHN_AUTHENTICATE_URL = new URL(
+  "../webauthn/authenticate",
+  window.location
+);
+/**
+ * Authenticate an existing WebAuthn credential for the given email address
+ * @param {Object} props - The properties for registration
+ * @param {string} props.email - Email address to register
+ * @param {string} props.provider - WebAuthn provider
+ * @param {string} props.challenge - PKCE challenge
+ * @returns {Promise<string | null>} - The PKCE code or null if the application
+ *   requires email verification
+ */
+export async function authenticate({ email, provider, challenge }) {
+  // Check if WebAuthn is supported
+  if (!window.PublicKeyCredential) {
+    console.error("WebAuthn is not supported in this browser.");
+    return;
+  }
+
+  // Fetch WebAuthn options from the server
+  const options = await getAuthenticateOptions(email);
+
+  // Get the existing credentials assertion
+  const assertion = await navigator.credentials.get({
+    publicKey: {
+      ...options,
+      challenge: decodeBase64Url(options.challenge),
+      allowCredentials: options.allowCredentials.map((credential) => ({
+        ...credential,
+        id: decodeBase64Url(credential.id),
+      })),
+    },
+  });
+
+  // Register the credentials on the server
+  const registerResult = await authenticateAssertion({
+    email,
+    assertion,
+    challenge,
+  });
+
+  return registerResult.code ?? null;
+}
+
+/**
+ * Fetch WebAuthn options from the server
+ * @param {string} email - Email address to register
+ * @returns {Promise<globalThis.PublicKeyCredentialCreationOptions>}
+ */
+async function getAuthenticateOptions(email) {
+  const url = new URL(WEBAUTHN_OPTIONS_URL);
+  url.searchParams.set("email", email);
+
+  const optionsResponse = await fetch(url, {
+    method: "GET",
+  });
+
+  if (!optionsResponse.ok) {
+    console.error(
+      "Failed to fetch WebAuthn options:",
+      optionsResponse.statusText
+    );
+    console.error(await optionsResponse.text());
+    throw new Error("Failed to fetch WebAuthn options");
+  }
+
+  try {
+    return await optionsResponse.json();
+  } catch (e) {
+    console.error("Failed to parse WebAuthn options:", e);
+    throw new Error("Failed to parse WebAuthn options");
+  }
+}
+
+/**
+ * Authenticate the credentials on the server
+ * @param {Object} props
+ * @param {string} props.email
+ * @param {Object} props.assertion
+ * @param {string} props.provider
+ * @param {string} props.challenge
+ * @returns {Promise<Object>}
+ */
+async function authenticateAssertion(props) {
+  // Assertion includes raw bytes, so need to be encoded as base64url
+  // for transmission
+  const encodedAssertion = {
+    ...props.assertion,
+    rawId: encodeBase64Url(new Uint8Array(props.assertion.rawId)),
+    response: {
+      ...props.assertion.response,
+      authenticatorData: encodeBase64Url(
+        new Uint8Array(props.assertion.response.authenticatorData)
+      ),
+      clientDataJSON: encodeBase64Url(
+        new Uint8Array(props.assertion.response.clientDataJSON)
+      ),
+      signature: encodeBase64Url(
+        new Uint8Array(props.assertion.response.signature)
+      ),
+      userHandle: props.assertion.response.userHandle
+        ? encodeBase64Url(new Uint8Array(props.assertion.response.userHandle))
+        : null,
+    },
+  };
+
+  const authenticateResponse = await fetch(WEBAUTHN_AUTHENTICATE_URL, {
+    method: "POST",
+    headers: {
+      "Content-Type": "application/json",
+    },
+    body: JSON.stringify({
+      email: props.email,
+      assertion: encodedAssertion,
+      provider: props.provider,
+      challenge: props.challenge,
+    }),
+  });
+
+  return await parseResponseAsJSON(authenticateResponse, [
+    (response, error) => {
+      if (response.status === 401 && error?.type === "VerificationRequired") {
+        console.error(
+          "User's email is not verified",
+          response.statusText,
+          JSON.stringify(error)
+        );
+        throw new Error(
+          "Please verify your email before attempting to sign in."
+        );
+      }
+    },
+    (response, error) => {
+      console.error(
+        "Failed to authenticate WebAuthn credentials:",
+        response.statusText,
+        JSON.stringify(error)
+      );
+      throw new Error("Failed to authenticate WebAuthn credentials");
+    },
+  ]);
+}

edb/server/protocol/auth_ext/data.py

@@ -182,3 +182,21 @@ def __init__(
         self.user_handle = base64.b64decode(user_handle)
         self.credential_id = base64.b64decode(credential_id)
         self.public_key = base64.b64decode(public_key)
+
+
+@dataclasses.dataclass
+class WebAuthnAuthenticationChallenge:
+    id: str
+    created_at: datetime.datetime
+    modified_at: datetime.datetime
+    challenge: bytes
+    factor: WebAuthnFactor
+
+    def __init__(self, *, id, created_at, modified_at, challenge, factor):
+        self.id = id
+        self.created_at = created_at
+        self.modified_at = modified_at
+        self.challenge = base64.b64decode(challenge)
+        self.factor = (
+            WebAuthnFactor(**factor) if isinstance(factor, dict) else factor
+        )