From 9636f33fdbc070afcc80321359621c3bfe75535d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Garc=C3=ADa?=
 <dani-garcia@users.noreply.github.com>
Date: Mon, 11 Feb 2019 23:45:55 +0100
Subject: [PATCH] Implement constant time equal check for admin, 2fa recover
 and 2fa remember tokens

---
 src/api/admin.rs      | 2 +-
 src/api/identity.rs   | 3 ++-
 src/crypto.rs         | 9 +++++++++
 src/db/models/user.rs | 2 +-
 4 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/src/api/admin.rs b/src/api/admin.rs
index 1e7acdda..37b03c17 100644
--- a/src/api/admin.rs
+++ b/src/api/admin.rs
@@ -89,7 +89,7 @@ fn post_admin_login(data: Form<LoginForm>, mut cookies: Cookies, ip: ClientIp) -
 fn _validate_token(token: &str) -> bool {
     match CONFIG.admin_token().as_ref() {
         None => false,
-        Some(t) => t == token,
+        Some(t) => crate::crypto::ct_eq(t, token),
     }
 }
 
diff --git a/src/api/identity.rs b/src/api/identity.rs
index 8638796b..5e38e20b 100644
--- a/src/api/identity.rs
+++ b/src/api/identity.rs
@@ -170,8 +170,9 @@ fn twofactor_auth(
 
     match TwoFactorType::from_i32(provider) {
         Some(TwoFactorType::Remember) => {
+            use crate::crypto::ct_eq;
             match device.twofactor_remember {
-                Some(ref remember) if remember == twofactor_code => return Ok(None), // No twofactor token needed here
+                Some(ref remember) if ct_eq(remember, twofactor_code) => return Ok(None), // No twofactor token needed here
                 _ => err_json!(_json_err_twofactor(&providers, user_uuid, conn)?),
             }
         }
diff --git a/src/crypto.rs b/src/crypto.rs
index 9321f25f..628afcd0 100644
--- a/src/crypto.rs
+++ b/src/crypto.rs
@@ -36,3 +36,12 @@ pub fn get_random(mut array: Vec<u8>) -> Vec<u8> {
 
     array
 }
+
+//
+// Constant time compare
+//
+pub fn ct_eq<T: AsRef<[u8]>, U: AsRef<[u8]>>(a: T, b: U) -> bool {
+    use ring::constant_time::verify_slices_are_equal;
+
+    verify_slices_are_equal(a.as_ref(), b.as_ref()).is_ok()
+}
diff --git a/src/db/models/user.rs b/src/db/models/user.rs
index 21ac1531..94ddc1ab 100644
--- a/src/db/models/user.rs
+++ b/src/db/models/user.rs
@@ -86,7 +86,7 @@ impl User {
 
     pub fn check_valid_recovery_code(&self, recovery_code: &str) -> bool {
         if let Some(ref totp_recover) = self.totp_recover {
-            recovery_code == totp_recover.to_lowercase()
+            crate::crypto::ct_eq(recovery_code, totp_recover.to_lowercase())
         } else {
             false
         }