Verify user is signed in and can actually resolve conflicts

app/controllers/projects/merge_requests_controller.rb

@@ -28,6 +28,8 @@ class Projects::MergeRequestsController < Projects::ApplicationController
   # Allow modify merge_request
   before_action :authorize_update_merge_request!, only: [:close, :edit, :update, :remove_wip, :sort]
 
+  before_action :authorize_can_resolve_conflicts!, only: [:conflicts, :resolve_conflicts]
+
   def index
     terms = params['issue_search']
     @merge_requests = merge_requests_collection
@@ -368,6 +370,10 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     return render_404 unless can?(current_user, :admin_merge_request, @merge_request)
   end
 
+  def authorize_can_resolve_conflicts!
+    return render_404 unless @merge_request.conflicts_can_be_resolved_by?(current_user)
+  end
+
   def module_enabled
     return render_404 unless @project.merge_requests_enabled
   end

app/models/merge_request.rb

@@ -720,6 +720,11 @@ class MergeRequest < ActiveRecord::Base
     @conflicts ||= Gitlab::Conflict::FileCollection.new(self)
   end
 
+  def conflicts_can_be_resolved_by?(user)
+    access = ::Gitlab::UserAccess.new(user, project: source_project)
+    access.can_push_to_branch?(source_branch)
+  end
+
   def conflicts_can_be_resolved_in_ui?
     return @conflicts_can_be_resolved_in_ui if defined?(@conflicts_can_be_resolved_in_ui)
 

app/views/projects/merge_requests/widget/open/_conflicts.html.haml

@@ -4,9 +4,11 @@
 
 %p
   Please
+  - if @merge_request.conflicts_can_be_resolved_by?(current_user)
     - if @merge_request.conflicts_can_be_resolved_in_ui?
       = link_to "resolve these conflicts", conflicts_namespace_project_merge_request_path(@project.namespace, @project, @merge_request)
       or
+
   - if @merge_request.can_be_merged_via_command_line_by?(current_user)
     #{link_to "merge this request manually", "#modal_merge_info", class: "how_to_merge_link vlink", "data-toggle" => "modal"}.
   - else