Merge branch 'jej-note-search-uses-finder' into 'security'

Fix missing Note access checks in by moving Note#search to updated NoteFinder

Split from !2024 to partially solve https://gitlab.com/gitlab-org/gitlab-ce/issues/23867

## Which fixes are in this MR?

:warning: - Potentially untested  
:bomb: - No test coverage  
:traffic_light: - Test coverage of some sort exists (a test failed when error raised)  
:vertical_traffic_light: - Test coverage of return value (a test failed when nil used)  
:white_check_mark: - Permissions check tested

### Note lookup without access check

- [x] :white_check_mark: app/finders/notes_finder.rb:13 :download_code check
- [x] :white_check_mark: app/finders/notes_finder.rb:19 `SnippetsFinder`
- [x] :white_check_mark: app/models/note.rb:121 [`Issue#visible_to_user`]
- [x] :white_check_mark: lib/gitlab/project_search_results.rb:113
  - This is the only use of `app/models/note.rb:121` above, but importantly has no access checks at all. This means it leaks MR comments and snippets when those features are `team-only` in addition to the issue comments which would be fixed by `app/models/note.rb:121`.
  - It is only called from SearchController where `can?(current_user, :download_code, @project)` is checked, so commit comments are not leaked.

### Previous discussions
- [x] https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#b915c5267a63628b0bafd23d37792ae73ceae272_13_13 `: download_code` check on commit
- [x] https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#b915c5267a63628b0bafd23d37792ae73ceae272_19_19 `SnippetsFinder` should be used
  - `SnippetsFinder` should check if the snippets feature is enabled -> https://gitlab.com/gitlab-org/gitlab-ce/issues/25223

###  Acceptance criteria met?
- [x] Tests added for new code
- [x] TODO comments removed
- [x] Squashed and removed skipped tests
- [x] Changelog entry
- [ ] State Gitlab versions affected and issue severity in description
- [ ] Create technical debt issue for NotesFinder.
  - Either split into `NotesFinder::ForTarget` and `NotesFinder::Search` or consider object per notable type such as `NotesFinder::OnIssue`. For the first option could create `NotesFinder::Base` which is either inherited from or which can be included in the other two.
  - Avoid case statement anti-pattern in this finder with use of `NotesFinder::OnCommit` etc. Consider something on the finder for this? `Model.finder(user, project)`
  - Move `inc_author` to the controller, and implement `related_notes` to replace `non_diff_notes`/`mr_and_commit_notes`

See merge request !2035

1 files changed, 61 insertions, 0 deletions

diff --git a/spec/controllers/search_controller_spec.rb b/spec/controllers/search_controller_spec.rb
new file mode 100644
index 00000000000..b7bb9290712
--- /dev/null
+++ b/spec/controllers/search_controller_spec.rb
@@ -0,0 +1,61 @@
+require 'spec_helper'
+
+describe SearchController do
+  let(:user)    { create(:user) }
+  let(:project) { create(:empty_project, :public) }
+
+  before do
+    sign_in(user)
+  end
+
+  it 'finds issue comments' do
+    project = create(:empty_project, :public)
+    note = create(:note_on_issue, project: project)
+
+    get :show, project_id: project.id, scope: 'notes', search: note.note
+
+    expect(assigns[:search_objects].first).to eq note
+  end
+
+  context 'on restricted projects' do
+    context 'when signed out' do
+      before { sign_out(user) }
+
+      it "doesn't expose comments on issues" do
+        project = create(:empty_project, :public, issues_access_level: ProjectFeature::PRIVATE)
+        note = create(:note_on_issue, project: project)
+
+        get :show, project_id: project.id, scope: 'notes', search: note.note
+
+        expect(assigns[:search_objects].count).to eq(0)
+      end
+    end
+
+    it "doesn't expose comments on issues" do
+      project = create(:empty_project, :public, issues_access_level: ProjectFeature::PRIVATE)
+      note = create(:note_on_issue, project: project)
+
+      get :show, project_id: project.id, scope: 'notes', search: note.note
+
+      expect(assigns[:search_objects].count).to eq(0)
+    end
+
+    it "doesn't expose comments on merge_requests" do
+      project = create(:empty_project, :public, merge_requests_access_level: ProjectFeature::PRIVATE)
+      note = create(:note_on_merge_request, project: project)
+
+      get :show, project_id: project.id, scope: 'notes', search: note.note
+
+      expect(assigns[:search_objects].count).to eq(0)
+    end
+
+    it "doesn't expose comments on snippets" do
+      project = create(:empty_project, :public, snippets_access_level: ProjectFeature::PRIVATE)
+      note = create(:note_on_project_snippet, project: project)
+
+      get :show, project_id: project.id, scope: 'notes', search: note.note
+
+      expect(assigns[:search_objects].count).to eq(0)
+    end
+  end
+end