Add optional state file permissions

Before this commit, it was possible that the puma.state file would be world readable which may not be desirable in production environments. This introduces a new optional configuration option to set desired state file permissions.

History.md

@@ -10,6 +10,7 @@
   * Increases maximum URI path length from 2048 to 8196 bytes (#2167)
   * Force shutdown responses can be overridden by using the `lowlevel_error_handler` config (#2203)
   * Faster phased restart and worker timeout (#2121)
+  * New configuration option to set state file permissions (#2238)
 
 * Deprecations, Removals and Breaking API Changes
   * `Puma.stats` now returns a Hash instead of a JSON string (#2086)

lib/puma/dsl.rb

@@ -399,6 +399,14 @@ def state_path(path)
       @options[:state] = path.to_s
     end
 
+    # Use +permission+ to restrict permissions for the state file.
+    #
+    # @example
+    #   state_permission 0600
+    def state_permission(permission)
+      @options[:state_permission] = permission
+    end
+
     # How many worker processes to run.  Typically this is set to
     # the number of available cores.
     #

lib/puma/launcher.rb

@@ -102,6 +102,7 @@ def write_state
       write_pid
 
       path = @options[:state]
+      permission = @options[:state_permission]
       return unless path
 
       require 'puma/state_file'
@@ -111,7 +112,7 @@ def write_state
       sf.control_url = @options[:control_url]
       sf.control_auth_token = @options[:control_auth_token]
 
-      sf.save path
+      sf.save path, permission
     end
 
     # Delete the configured pidfile

lib/puma/state_file.rb

@@ -8,8 +8,9 @@ def initialize
       @options = {}
     end
 
-    def save(path)
+    def save(path, permission = nil)
       File.write path, YAML.dump(@options)
+      File.chmod(permission, path) if permission
     end
 
     def load(path)

test/test_launcher.rb

@@ -79,6 +79,54 @@ def test_pid_file
     File.unlink tmp_path
   end
 
+  def test_state_permission_0640
+    tmp_file = Tempfile.new("puma-state")
+    tmp_path = tmp_file.path
+    tmp_permission = 0640
+
+    conf = Puma::Configuration.new do |c|
+      c.state_path tmp_path
+      c.state_permission tmp_permission
+    end
+
+    launcher(conf).write_state
+
+    assert File.stat(tmp_path).mode.to_s(8)[-4..-1], tmp_permission
+  ensure
+    File.unlink tmp_path
+  end
+
+  def test_state_permission_nil
+    tmp_file = Tempfile.new("puma-state")
+    tmp_path = tmp_file.path
+
+    conf = Puma::Configuration.new do |c|
+      c.state_path tmp_path
+      c.state_permission nil
+    end
+
+    launcher(conf).write_state
+
+    assert File.exist?(tmp_path)
+  ensure
+    File.unlink tmp_path if tmp_path
+  end
+
+  def test_no_state_permission
+    tmp_file = Tempfile.new("puma-state")
+    tmp_path = tmp_file.path
+
+    conf = Puma::Configuration.new do |c|
+      c.state_path tmp_path
+    end
+
+    launcher(conf).write_state
+
+    assert File.exist?(tmp_path)
+  ensure
+    File.unlink tmp_path if tmp_path
+  end
+
   def test_puma_stats
     conf = Puma::Configuration.new do |c|
       c.app -> {[200, {}, ['']]}