From 85c6eb9b085ac583f0122d3186a964c3509c4360 Mon Sep 17 00:00:00 2001
From: Robin Ward <robin.ward@gmail.com>
Date: Thu, 28 Aug 2014 17:45:13 -0400
Subject: [PATCH] SECURITY: Only redirect to our host by path on the login
 action

---
 app/controllers/static_controller.rb       | 20 ++++++++++++++------
 spec/controllers/static_controller_spec.rb | 21 +++++++++++++++++++++
 2 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/app/controllers/static_controller.rb b/app/controllers/static_controller.rb
index f29c24b63..3a452362c 100644
--- a/app/controllers/static_controller.rb
+++ b/app/controllers/static_controller.rb
@@ -54,13 +54,21 @@ class StaticController < ApplicationController
     params.delete(:username)
     params.delete(:password)
 
-    redirect_to(
-      if params[:redirect].blank? || params[:redirect].match(login_path)
-        "/"
-      else
-        params[:redirect]
+    destination = "/"
+
+    if params[:redirect].present? && !params[:redirect].match(login_path)
+      begin
+        forum_uri = URI(Discourse.base_url)
+        uri = URI(params[:redirect])
+        if uri.path.present? && (uri.host.blank? || uri.host == forum_uri.host)
+          destination = uri.path
+        end
+      rescue URI::InvalidURIError
+        # Do nothing if the URI is invalid
       end
-    )
+    end
+
+    redirect_to destination
   end
 
   skip_before_filter :verify_authenticity_token, only: [:cdn_asset]
diff --git a/spec/controllers/static_controller_spec.rb b/spec/controllers/static_controller_spec.rb
index 4b1a63805..86c185503 100644
--- a/spec/controllers/static_controller_spec.rb
+++ b/spec/controllers/static_controller_spec.rb
@@ -82,6 +82,27 @@ describe StaticController do
       end
     end
 
+    context 'with a full url' do
+      it 'redirects to the correct path' do
+        xhr :post, :enter, redirect: "#{Discourse.base_url}/foo"
+        expect(response).to redirect_to '/foo'
+      end
+    end
+
+    context 'with a full url to someone else' do
+      it 'redirects to the root path' do
+        xhr :post, :enter, redirect: "http://eviltrout.com/foo"
+        expect(response).to redirect_to '/'
+      end
+    end
+
+    context 'with an invalid URL' do
+      it "redirects to the root" do
+        xhr :post, :enter, redirect: "javascript:alert('trout')"
+        expect(response).to redirect_to '/'
+      end
+    end
+
     context 'when the redirect path is the login page' do
       it 'redirects to the root url' do
         xhr :post, :enter, redirect: login_path