Merge branch 'fix-restricted-visibility' into 'master'

Restricted visibility levels - bug fix and new feature

This allows admin users to override restricted visibility settings when creating and updating projects and snippets, and moves the restricted visibility configuration from gitlab.yml to the web UI.  See #1903.

## Move configuration location

I added a new section to the application settings page for restricted visibility levels.  Each level has a checkbox, styled with Bootstrap to look like a toggle button.  A checked box means that the level is restricted.  I added a glowing text shadow and changed the background color for checked buttons because the default styles made it hard to distinguish between checked and unchecked.  This image shows the new section with the "Public" box checked:

![restricted_visibility_settings](https://dev.gitlab.org/Okada/gitlabhq/uploads/629562e4313f89b795e81c3bb0f95893/restricted_visibility_settings.png)

## Allow admins to override

To allow admin users to override the restricted visibility levels, I had to remove the `visibility_level` validation from the `Project` class.  The model doesn't know about the `current_user`, which should determine whether the restrictions can be overridden.  We could use the creator in the validation, but that wouldn't work correctly for projects where a non-admin user is the creator and an admin tries to change the project to a restricted visibility level.

The `Project::UpdateService` and `Project::CreateService` classes already had code to determine whether the current user is allowed to use a given visibility level; now all visibility level validation is done in those classes.  Currently, when a non-admin tries to create or update a project using a restricted level, these classes silently set the visibility level to the global default (create) or the project's existing value (update).  I changed this behavior to be more like an Active Model validation, where using a restricted level causes the entire request to be rejected.

Project and personal snippets didn't have service classes, and restricted visibility levels weren't being enforced in the model or the controllers.  The UI disabled radio buttons for restricted levels, but that wouldn't be difficult to circumvent.  I created the `CreateSnippetService` and `UpdateSnippetService` classes to do the same restricted visibility check that the project classes do.  And since I was dealing with snippet visibility levels, I updated the API endpoints for project snippets to allow users to set and update the visibility level.

## TODO

* [x] Add more tests for restricted visibility functionality

cc @sytse @dzaporozhets

See merge request !1655

5 files changed, 68 insertions, 7 deletions

diff --git a/app/services/base_service.rb b/app/services/base_service.rb
index 52ab29f1492..6d9ed345914 100644
--- a/app/services/base_service.rb
+++ b/app/services/base_service.rb
@@ -31,8 +31,19 @@ class BaseService
     SystemHooksService.new
   end
 
-  def current_application_settings
-    ApplicationSetting.current
+  # Add an error to the specified model for restricted visibility levels
+  def deny_visibility_level(model, denied_visibility_level = nil)
+    denied_visibility_level ||= model.visibility_level
+
+    level_name = 'Unknown'
+    Gitlab::VisibilityLevel.options.each do |name, level|
+      level_name = name if level == denied_visibility_level
+    end
+
+    model.errors.add(
+      :visibility_level,
+      "#{level_name} visibility has been restricted by your GitLab administrator"
+    )
   end
 
   private
diff --git a/app/services/create_snippet_service.rb b/app/services/create_snippet_service.rb
new file mode 100644
index 00000000000..101a3df5eee
--- /dev/null
+++ b/app/services/create_snippet_service.rb
@@ -0,0 +1,20 @@
+class CreateSnippetService < BaseService
+  def execute
+    if project.nil?
+      snippet = PersonalSnippet.new(params)
+    else
+      snippet = project.snippets.build(params)
+    end
+
+    unless Gitlab::VisibilityLevel.allowed_for?(current_user,
+                                                params[:visibility_level])
+      deny_visibility_level(snippet)
+      return snippet
+    end
+
+    snippet.author = current_user
+
+    snippet.save
+    snippet
+  end
+end
diff --git a/app/services/projects/create_service.rb b/app/services/projects/create_service.rb
index 4fe790b98f1..7ffd0b3882a 100644
--- a/app/services/projects/create_service.rb
+++ b/app/services/projects/create_service.rb
@@ -7,9 +7,12 @@ module Projects
     def execute
       @project = Project.new(params)
 
-      # Reset visibility level if is not allowed to set it
-      unless Gitlab::VisibilityLevel.allowed_for?(current_user, params[:visibility_level])
-        @project.visibility_level = default_features.visibility_level
+      # Make sure that the user is allowed to use the specified visibility
+      # level
+      unless Gitlab::VisibilityLevel.allowed_for?(current_user,
+                                                  params[:visibility_level])
+        deny_visibility_level(@project)
+        return @project
       end
 
       # Set project name from path
diff --git a/app/services/projects/update_service.rb b/app/services/projects/update_service.rb
index 36877a61679..69bdd045ddf 100644
--- a/app/services/projects/update_service.rb
+++ b/app/services/projects/update_service.rb
@@ -2,8 +2,13 @@ module Projects
   class UpdateService < BaseService
     def execute
       # check that user is allowed to set specified visibility_level
-      unless can?(current_user, :change_visibility_level, project) && Gitlab::VisibilityLevel.allowed_for?(current_user, params[:visibility_level])
-        params[:visibility_level] = project.visibility_level
+      new_visibility = params[:visibility_level]
+      if new_visibility && new_visibility.to_i != project.visibility_level
+        unless can?(current_user, :change_visibility_level, project) &&
+          Gitlab::VisibilityLevel.allowed_for?(current_user, new_visibility)
+          deny_visibility_level(project, new_visibility)
+          return project
+        end
       end
 
       new_branch = params[:default_branch]
diff --git a/app/services/update_snippet_service.rb b/app/services/update_snippet_service.rb
new file mode 100644
index 00000000000..9d181c2d2ab
--- /dev/null
+++ b/app/services/update_snippet_service.rb
@@ -0,0 +1,22 @@
+class UpdateSnippetService < BaseService
+  attr_accessor :snippet
+
+  def initialize(project, user, snippet, params)
+    super(project, user, params)
+    @snippet = snippet
+  end
+
+  def execute
+    # check that user is allowed to set specified visibility_level
+    new_visibility = params[:visibility_level]
+    if new_visibility && new_visibility.to_i != snippet.visibility_level
+      unless can?(current_user, :change_visibility_level, snippet) &&
+        Gitlab::VisibilityLevel.allowed_for?(current_user, new_visibility)
+        deny_visibility_level(snippet, new_visibility)
+        return snippet
+      end
+    end
+
+    snippet.update_attributes(params)
+  end
+end