Add latest changes from gitlab-org/security/gitlab@15-4-stable-ee

4 files changed, 67 insertions, 24 deletions

diff --git a/app/uploaders/file_uploader.rb b/app/uploaders/file_uploader.rb
index bf5be708060..7250ce5c0b0 100644
--- a/app/uploaders/file_uploader.rb
+++ b/app/uploaders/file_uploader.rb
@@ -14,7 +14,12 @@ class FileUploader < GitlabUploader
   include ObjectStorage::Concern
   prepend ObjectStorage::Extension::RecordsUploads
 
-  MARKDOWN_PATTERN = %r{\!?\[.*?\]\(/uploads/(?<secret>[0-9a-f]{32})/(?<file>.*?)\)}.freeze
+  # This pattern is vulnerable to malicious inputs, so use Gitlab::UntrustedRegexp
+  # to place bounds on execution time
+  MARKDOWN_PATTERN = Gitlab::UntrustedRegexp.new(
+    '!?\[.*?\]\(/uploads/(?P<secret>[0-9a-f]{32})/(?P<file>.*?)\)'
+  )
+
   DYNAMIC_PATH_PATTERN = %r{.*(?<secret>\b(\h{10}|\h{32}))\/(?<identifier>.*)}.freeze
   VALID_SECRET_PATTERN = %r{\A\h{10,32}\z}.freeze
 
diff --git a/lib/gitlab/gfm/uploads_rewriter.rb b/lib/gitlab/gfm/uploads_rewriter.rb
index b0bf68f4204..58b46a85aae 100644
--- a/lib/gitlab/gfm/uploads_rewriter.rb
+++ b/lib/gitlab/gfm/uploads_rewriter.rb
@@ -23,33 +23,24 @@ module Gitlab
       def rewrite(target_parent)
         return @text unless needs_rewrite?
 
-        @text.gsub!(@pattern) do |markdown|
-          file = find_file($~[:secret], $~[:file])
-          # No file will be returned for a path traversal
-          next if file.nil?
+        @target_parent = target_parent
 
-          break markdown unless file.try(:exists?)
-
-          klass = target_parent.is_a?(Namespace) ? NamespaceFileUploader : FileUploader
-          moved = klass.copy_to(file, target_parent)
-
-          moved_markdown = moved.markdown_link
-
-          # Prevents rewrite of plain links as embedded
-          if was_embedded?(markdown)
-            moved_markdown
-          else
-            moved_markdown.delete_prefix('!')
-          end
+        rewritten_text = Gitlab::StringRegexMarker.new(@text).mark(@pattern) do |markdown, left:, right:, mode:|
+          transform_markdown(markdown)
         end
+
+        # MarkdownContentRewriterService relies on the text being changed _in place_.
+        @text.gsub!(@text, rewritten_text)
       end
 
       def needs_rewrite?
         strong_memoize(:needs_rewrite) do
-          FileUploader::MARKDOWN_PATTERN.match?(@text)
+          @pattern.match?(@text)
         end
       end
 
+      private
+
       def was_embedded?(markdown)
         markdown.starts_with?("!")
       end
@@ -57,6 +48,28 @@ module Gitlab
       def find_file(secret, file_name)
         UploaderFinder.new(@source_project, secret, file_name).execute
       end
+
+      def transform_markdown(markdown)
+        match = @pattern.match(markdown)
+        file = find_file(match[:secret], match[:file])
+
+        # No file will be returned for a path traversal
+        return '' if file.nil?
+
+        return markdown unless file.try(:exists?)
+
+        klass = @target_parent.is_a?(Namespace) ? NamespaceFileUploader : FileUploader
+        moved = klass.copy_to(file, @target_parent)
+
+        moved_markdown = moved.markdown_link
+
+        # Prevents rewrite of plain links as embedded
+        if was_embedded?(markdown)
+          moved_markdown
+        else
+          moved_markdown.delete_prefix('!')
+        end
+      end
     end
   end
 end
diff --git a/spec/lib/gitlab/gfm/uploads_rewriter_spec.rb b/spec/lib/gitlab/gfm/uploads_rewriter_spec.rb
index a16f96a7d11..b1bff242f33 100644
--- a/spec/lib/gitlab/gfm/uploads_rewriter_spec.rb
+++ b/spec/lib/gitlab/gfm/uploads_rewriter_spec.rb
@@ -23,8 +23,9 @@ RSpec.describe Gitlab::Gfm::UploadsRewriter do
     end
 
     def referenced_files(text, project)
-      referenced_files = text.scan(FileUploader::MARKDOWN_PATTERN).map do
-        UploaderFinder.new(project, $~[:secret], $~[:file]).execute
+      scanner = FileUploader::MARKDOWN_PATTERN.scan(text)
+      referenced_files = scanner.map do |match|
+        UploaderFinder.new(project, match[0], match[1]).execute
       end
 
       referenced_files.compact.select(&:exists?)
@@ -32,7 +33,9 @@ RSpec.describe Gitlab::Gfm::UploadsRewriter do
 
     shared_examples "files are accessible" do
       describe '#rewrite' do
-        let!(:new_text) { rewriter.rewrite(new_project) }
+        subject(:rewrite) { new_text }
+
+        let(:new_text) { rewriter.rewrite(new_project) }
 
         let(:old_files) { [image_uploader, zip_uploader] }
         let(:new_files) do
@@ -43,11 +46,15 @@ RSpec.describe Gitlab::Gfm::UploadsRewriter do
         let(:new_paths) { new_files.map(&:path) }
 
         it 'rewrites content' do
+          rewrite
+
           expect(new_text).not_to eq text
           expect(new_text.length).to eq text.length
         end
 
         it 'copies files' do
+          rewrite
+
           expect(new_files).to all(exist)
           expect(old_paths).not_to match_array new_paths
           expect(old_paths).to all(include(old_project.disk_path))
@@ -55,10 +62,14 @@ RSpec.describe Gitlab::Gfm::UploadsRewriter do
         end
 
         it 'does not remove old files' do
+          rewrite
+
           expect(old_files).to all(exist)
         end
 
         it 'generates a new secret for each file' do
+          rewrite
+
           expect(new_paths).not_to include image_uploader.secret
           expect(new_paths).not_to include zip_uploader.secret
         end
@@ -68,6 +79,8 @@ RSpec.describe Gitlab::Gfm::UploadsRewriter do
             allow(finder).to receive(:execute).and_return(nil)
           end
 
+          rewrite
+
           expect(new_files).to be_empty
         end
       end
@@ -84,6 +97,16 @@ RSpec.describe Gitlab::Gfm::UploadsRewriter do
       expect(moved_text.scan(/\A\[.*?\]/).count).to eq(1)
     end
 
+    it 'does not casue a timeout on pathological text' do
+      text = '[!l' * 30000
+
+      Timeout.timeout(3) do
+        moved_text = described_class.new(text, nil, old_project, user).rewrite(new_project)
+
+        expect(moved_text).to eq(text)
+      end
+    end
+
     context "file are stored locally" do
       include_examples "files are accessible"
     end
diff --git a/spec/services/notes/copy_service_spec.rb b/spec/services/notes/copy_service_spec.rb
index f146a49e929..2fa9a462bb9 100644
--- a/spec/services/notes/copy_service_spec.rb
+++ b/spec/services/notes/copy_service_spec.rb
@@ -146,8 +146,10 @@ RSpec.describe Notes::CopyService do
           new_note = to_noteable.notes.first
 
           aggregate_failures do
-            expect(note.note).to match(/Simple text with image: #{FileUploader::MARKDOWN_PATTERN}/o)
-            expect(new_note.note).to match(/Simple text with image: #{FileUploader::MARKDOWN_PATTERN}/o)
+            expect(note.note).to match(/Simple text with image:/o)
+            expect(FileUploader::MARKDOWN_PATTERN.match(note.note)).not_to be_nil
+            expect(new_note.note).to match(/Simple text with image:/o)
+            expect(FileUploader::MARKDOWN_PATTERN.match(new_note.note)).not_to be_nil
             expect(note.note).not_to eq(new_note.note)
             expect(note.note_html).not_to eq(new_note.note_html)
           end