sandbox: deny signal to other processes

Library/Homebrew/sandbox.rb

@@ -302,6 +302,7 @@ class Sandbox
           (literal "/bin/ps")
           (with no-sandbox)
           ) ; allow certain processes running without sandbox
+      (deny signal (target others)) ; deny sending signals to other processes
       (allow default) ; allow everything else
     ERB
 

Library/Homebrew/test/sandbox_spec.rb

@@ -129,4 +129,22 @@ RSpec.describe Sandbox, :needs_macos do
       end
     end
   end
+
+  describe "#disallow sending signal to other processes" do
+    # we have to spawn a process, otherwise kill doesn't try to send a signal if the process doesn't exist
+    let(:pid) do
+      pid = spawn("sleep 1000")
+      sleep 1 # Ensure the process has started
+      pid
+    end
+
+    after do
+      Process.kill("KILL", pid)
+      Process.wait(pid)
+    end
+
+    it "sandbox stops signal to other processes" do
+      expect { sandbox.exec "kill", "-SIGTERM", pid.to_s }.to raise_error(ErrorDuringExecution)
+    end
+  end
 end