Merge branch 'rack-request-trusted-proxies' into 'master'

Make Rack::Request use our trusted proxies when filtering IP addresses

## What does this MR do?

This allows us to control the trusted proxies while deployed in a private network.

## Are there points in the code the reviewer needs to double check?

If we want to limit what is impacted, we can do this specifically for the rack_attack request object.

## Why was this MR needed?

Normally Rack::Request will trust all private IPs as trusted proxies, which can cause problems if your users are connection on you network via private IP ranges.
    
Normally in a rails app this is handled by action_dispatch request, but rack_attack is specifically using the Rack::Request object instead.

## What are the relevant issue numbers?

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/17550

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- [ ] ~~API support added~~
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)


\cc @stanhu

See merge request !4958

CHANGELOG

@@ -8,6 +8,7 @@ v 8.10.0 (unreleased)
   - Wrap code blocks on Activies and Todos page. !4783 (winniehell)
   - Align flash messages with left side of page content !4959 (winniehell)
   - Display last commit of deleted branch in push events !4699 (winniehell)
+  - Apply the trusted_proxies config to the rack request object for use with rack_attack
   - Add Sidekiq queue duration to transaction metrics.
   - Let Workhorse serve format-patch diffs
   - Make images fit to the size of the viewport !4810

config/initializers/trusted_proxies.rb

+# Override Rack::Request to make use of the same list of trusted_proxies
+# as the ActionDispatch::Request object. This is necessary for libraries
+# like rack_attack where they don't use ActionDispatch, and we want them
+# to block/throttle requests on private networks.
+# Rack Attack specific issue: https://github.com/kickstarter/rack-attack/issues/145 
+module Rack
+  class Request
+    def trusted_proxy?(ip)
+      Rails.application.config.action_dispatch.trusted_proxies.any? { |proxy| proxy === ip }
+    end
+  end
+end
+
 Rails.application.config.action_dispatch.trusted_proxies = (
   [ '127.0.0.1', '::1' ] + Array(Gitlab.config.gitlab.trusted_proxies)
 ).map { |proxy| IPAddr.new(proxy) }

spec/initializers/trusted_proxies_spec.rb

@@ -6,14 +6,16 @@ describe 'trusted_proxies', lib: true do
       set_trusted_proxies([])
     end
 
-    it 'preserves private IPs as remote_ip' do
+    it 'preserves private IPs' do
       request = stub_request('HTTP_X_FORWARDED_FOR' => '10.1.5.89')
       expect(request.remote_ip).to eq('10.1.5.89')
+      expect(request.ip).to eq('10.1.5.89')
     end
 
-    it 'filters out localhost from remote_ip' do
+    it 'filters out localhost' do
       request = stub_request('HTTP_X_FORWARDED_FOR' => '1.1.1.1, 10.1.5.89, 127.0.0.1')
       expect(request.remote_ip).to eq('10.1.5.89')
+      expect(request.ip).to eq('10.1.5.89')
     end
   end
 
@@ -22,9 +24,10 @@ describe 'trusted_proxies', lib: true do
       set_trusted_proxies([ "10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16" ])
     end
 
-    it 'filters out private and local IPs from remote_ip' do
+    it 'filters out private and local IPs' do
       request = stub_request('HTTP_X_FORWARDED_FOR' => '1.2.3.6, 1.1.1.1, 10.1.5.89, 127.0.0.1')
       expect(request.remote_ip).to eq('1.1.1.1')
+      expect(request.ip).to eq('1.1.1.1')
     end
   end
 
@@ -33,9 +36,10 @@ describe 'trusted_proxies', lib: true do
       set_trusted_proxies([ "60.98.25.47" ])
     end
 
-    it 'filters out proxy IP from remote_ip' do
+    it 'filters out proxy IP' do
       request = stub_request('HTTP_X_FORWARDED_FOR' => '1.2.3.6, 1.1.1.1, 60.98.25.47, 127.0.0.1')
       expect(request.remote_ip).to eq('1.1.1.1')
+      expect(request.ip).to eq('1.1.1.1')
     end
   end