Add rate limiting for TOTP auth attempts

hc/accounts/tests/test_login_totp.py

@@ -1,6 +1,7 @@
 import time
 from unittest.mock import patch
 
+from hc.api.models import TokenBucket
 from hc.test import BaseTestCase
 
 
@@ -75,3 +76,11 @@ class LoginTotpTestCase(BaseTestCase):
 
         r = self.client.post(self.url, {"code": "000000"})
         self.assertContains(r, "The code you entered was incorrect.")
+
+    def test_it_uses_rate_limiting(self):
+        obj = TokenBucket(value=f"totp-{self.alice.id}")
+        obj.tokens = 0
+        obj.save()
+
+        r = self.client.post(self.url, {"code": "000000"})
+        self.assertContains(r, "Too Many Requests")

hc/accounts/views.py

@@ -848,6 +848,9 @@ def login_totp(request):
 
     totp = pyotp.totp.TOTP(user.profile.totp)
     if request.method == "POST":
+        if not TokenBucket.authorize_totp(user):
+            return render(request, "try_later.html")
+
         form = forms.TotpForm(totp, request.POST)
         if form.is_valid():
             request.session.pop("2fa_user")

hc/api/models.py

@@ -983,3 +983,11 @@ class TokenBucket(models.Model):
 
         # 10 sudo attempts per day
         return TokenBucket.authorize(value, 10, 3600 * 24)
+
+    @staticmethod
+    def authorize_totp(user):
+        value = "totp-%d" % user.id
+
+        # 96 attempts per 24 hours
+        # (or, on average, one attempt per 15 minutes)
+        return TokenBucket.authorize(value, 96, 3600 * 24)