Add support for MFA with Duo's Universal Prompt (dani-garcia#4637)

* Add initial working Duo Universal Prompt support.

* Add db schema and models for Duo 2FA state storage

* store duo states in the database and validate during authentication

* cleanup & comments

* bump state/nonce length

* replace stray use of TimeDelta

* more cleanup

* bind Duo oauth flow to device id, drop redundant device type handling

* drop redundant alphanum string generation code

* error handling cleanup

* directly use JWT_VALIDITY_SECS constant instead of copying it to DuoClient instances

* remove redundant explicit returns, rustfmt

* rearrange constants, update comments, error message

* override charset on duo state column to ascii for mysql

* Reduce twofactor_duo_ctx state/nonce column size in postgres and maria

* Add fixes suggested by clippy

* rustfmt

* Update to use the make_http_request

* Don't handle OrganizationDuo

* move Duo API endpoint fmt strings out of macros and into format! calls

* Add missing indentation

Co-authored-by: Daniel García <dani-garcia@users.noreply.github.com>

* remove redundant expiry check when purging Duo contexts

---------

Co-authored-by: BlackDex <black.dex@gmail.com>
Co-authored-by: Daniel García <dani-garcia@users.noreply.github.com>

.env.template

@@ -152,6 +152,10 @@
 ## Cron schedule of the job that cleans old auth requests from the auth request.
 ## Defaults to every minute. Set blank to disable this job.
 # AUTH_REQUEST_PURGE_SCHEDULE="30 * * * * *"
+##
+## Cron schedule of the job that cleans expired Duo contexts from the database. Does nothing if Duo MFA is disabled or set to use the legacy iframe prompt.
+## Defaults to every minute. Set blank to disable this job.
+# DUO_CONTEXT_PURGE_SCHEDULE="30 * * * * *"
 
 ########################
 ### General settings ###
@@ -423,15 +427,21 @@
 # YUBICO_SERVER=http://yourdomain.com/wsapi/2.0/verify
 
 ## Duo Settings
-## You need to configure all options to enable global Duo support, otherwise users would need to configure it themselves
+## You need to configure the DUO_IKEY, DUO_SKEY, and DUO_HOST options to enable global Duo support.
+## Otherwise users will need to configure it themselves.
 ## Create an account and protect an application as mentioned in this link (only the first step, not the rest):
 ## https://help.bitwarden.com/article/setup-two-step-login-duo/#create-a-duo-security-account
 ## Then set the following options, based on the values obtained from the last step:
-# DUO_IKEY=<Integration Key>
-# DUO_SKEY=<Secret Key>
+# DUO_IKEY=<Client ID>
+# DUO_SKEY=<Client Secret>
 # DUO_HOST=<API Hostname>
 ## After that, you should be able to follow the rest of the guide linked above,
 ## ignoring the fields that ask for the values that you already configured beforehand.
+##
+## If you want to attempt to use Duo's 'Traditional Prompt' (deprecated, iframe based) set DUO_USE_IFRAME to 'true'.
+## Duo no longer supports this, but it still works for some integrations.
+## If you aren't sure, leave this alone.
+# DUO_USE_IFRAME=false
 
 ## Email 2FA settings
 ## Email token size

migrations/mysql/2024-06-05-131359_add_2fa_duo_store/down.sql

@@ -0,0 +1 @@
+DROP TABLE twofactor_duo_ctx;

migrations/mysql/2024-06-05-131359_add_2fa_duo_store/up.sql

@@ -0,0 +1,8 @@
+CREATE TABLE twofactor_duo_ctx (
+    state      VARCHAR(64)  NOT NULL,
+    user_email VARCHAR(255) NOT NULL,
+    nonce      VARCHAR(64)  NOT NULL,
+    exp        BIGINT       NOT NULL,
+
+    PRIMARY KEY (state)
+);

migrations/postgresql/2024-06-05-131359_add_2fa_duo_store/down.sql

@@ -0,0 +1 @@
+DROP TABLE twofactor_duo_ctx;

migrations/postgresql/2024-06-05-131359_add_2fa_duo_store/up.sql

@@ -0,0 +1,8 @@
+CREATE TABLE twofactor_duo_ctx (
+    state      VARCHAR(64) NOT NULL,
+    user_email VARCHAR(255)  NOT NULL,
+    nonce      VARCHAR(64) NOT NULL,
+    exp        BIGINT        NOT NULL,
+
+    PRIMARY KEY (state)
+);

migrations/sqlite/2024-06-05-131359_add_2fa_duo_store/down.sql

@@ -0,0 +1 @@
+DROP TABLE twofactor_duo_ctx;

migrations/sqlite/2024-06-05-131359_add_2fa_duo_store/up.sql

@@ -0,0 +1,8 @@
+CREATE TABLE twofactor_duo_ctx (
+    state      TEXT    NOT NULL,
+    user_email TEXT    NOT NULL,
+    nonce      TEXT    NOT NULL,
+    exp        INTEGER NOT NULL,
+
+    PRIMARY KEY (state)
+);

src/api/core/two_factor/duo.rs

@@ -252,7 +252,7 @@ async fn get_user_duo_data(uuid: &str, conn: &mut DbConn) -> DuoStatus {
 }
 
 // let (ik, sk, ak, host) = get_duo_keys();
-async fn get_duo_keys_email(email: &str, conn: &mut DbConn) -> ApiResult<(String, String, String, String)> {
+pub(crate) async fn get_duo_keys_email(email: &str, conn: &mut DbConn) -> ApiResult<(String, String, String, String)> {
     let data = match User::find_by_mail(email, conn).await {
         Some(u) => get_user_duo_data(&u.uuid, conn).await.data(),
         _ => DuoData::global(),