feat: Add support for configuration of XSLT security

ext/java/nokogiri/XsltStylesheet.java

@@ -350,4 +350,22 @@ public class XsltStylesheet extends RubyObject
     if (arg instanceof XmlDocument) { return; }
     throw runtime.newArgumentError("argument must be a Nokogiri::XML::Document");
   }
+
+  @JRubyMethod(meta = true, rest = true, name = "default_security_prefs")
+  public static IRubyObject
+  get_default_security_options(ThreadContext context, IRubyObject klazz, IRubyObject[] args)
+  {
+    // This method is not supported because the Java XML backend does not support the
+    // security controls supported by the libxml backend
+    throw context.getRuntime().newNotImplementedError("Nokogiri::XSLT::Stylesheet.default_security_prefs method is not implemented");
+  }
+
+  @JRubyMethod(meta = true, rest = true, name = "default_security_prefs=")
+  public static IRubyObject
+  set_default_security_options(ThreadContext context, IRubyObject klazz, IRubyObject[] args)
+  {
+    // This method is not supported because the Java XML backend does not support the
+    // security controls supported by the libxml backend
+    throw context.getRuntime().newNotImplementedError("Nokogiri::XSLT::Stylesheet.default_security_prefs= method is not implemented");
+  }
 }

ext/nokogiri/nokogiri.h

@@ -50,6 +50,7 @@
 #include <libxslt/extensions.h>
 #include <libxslt/xsltconfig.h>
 #include <libxslt/xsltutils.h>
+#include <libxslt/security.h>
 #include <libxslt/transform.h>
 #include <libxslt/imports.h>
 #include <libxslt/xsltInternals.h>

ext/nokogiri/xslt_stylesheet.c

@@ -1,6 +1,8 @@
 #include <nokogiri.h>
 
 VALUE cNokogiriXsltStylesheet ;
+VALUE mNokogiriXsltSecurity ;
+VALUE cNokogiriXsltSecurityConfig ;
 
 static void
 mark(void *data)
@@ -400,17 +402,65 @@ rb_xslt_s_register(VALUE self, VALUE uri, VALUE obj)
   return self;
 }
 
+static void
+add_sec_option(xsltSecurityPrefsPtr xsltPrefs, int option, VALUE val)
+{
+  if (val == Qtrue) {
+    xsltSetSecurityPrefs(xsltPrefs, option, xsltSecurityAllow);
+  } else if (val == Qfalse) {
+    xsltSetSecurityPrefs(xsltPrefs, option, xsltSecurityForbid);
+  }
+}
+
+static VALUE
+rb_set_default_security_options(VALUE self, VALUE options)
+{
+  Check_Type(options, T_OBJECT);
+  xsltSecurityPrefsPtr oldDefaults = xsltGetDefaultSecurityPrefs();
+  xsltSecurityPrefsPtr xsltPrefs = xsltNewSecurityPrefs();
+  add_sec_option(xsltPrefs, XSLT_SECPREF_READ_FILE, rb_iv_get(options, "@allow_read_file"));
+  add_sec_option(xsltPrefs, XSLT_SECPREF_WRITE_FILE, rb_iv_get(options, "@allow_write_file"));
+  add_sec_option(xsltPrefs, XSLT_SECPREF_CREATE_DIRECTORY, rb_iv_get(options, "@allow_create_directory"));
+  add_sec_option(xsltPrefs, XSLT_SECPREF_READ_NETWORK, rb_iv_get(options, "@allow_read_network"));
+  add_sec_option(xsltPrefs, XSLT_SECPREF_WRITE_NETWORK, rb_iv_get(options, "@allow_write_network"));
+  xsltSetDefaultSecurityPrefs(xsltPrefs);
+  if(oldDefaults) {
+    xsltFreeSecurityPrefs(oldDefaults);
+  }
+  return Qnil;
+}
+
+static VALUE
+rb_get_default_security_options(VALUE self)
+{
+  VALUE prefs = rb_funcall(cNokogiriXsltSecurityConfig, rb_intern("new"), 0);
+  xsltSecurityPrefsPtr xsltPrefs = xsltGetDefaultSecurityPrefs();
+  if(xsltPrefs == NULL) {
+    return prefs;
+  }
+  rb_iv_set(prefs, "@allow_read_file", xsltGetSecurityPrefs(xsltPrefs, XSLT_SECPREF_READ_FILE) == xsltSecurityAllow ? Qtrue : Qfalse);
+  rb_iv_set(prefs, "@allow_write_file", xsltGetSecurityPrefs(xsltPrefs, XSLT_SECPREF_WRITE_FILE) == xsltSecurityAllow ? Qtrue : Qfalse);
+  rb_iv_set(prefs, "@allow_create_directory", xsltGetSecurityPrefs(xsltPrefs, XSLT_SECPREF_CREATE_DIRECTORY) == xsltSecurityAllow ? Qtrue : Qfalse);
+  rb_iv_set(prefs, "@allow_read_network", xsltGetSecurityPrefs(xsltPrefs, XSLT_SECPREF_READ_NETWORK) == xsltSecurityAllow ? Qtrue : Qfalse);
+  rb_iv_set(prefs, "@allow_write_network", xsltGetSecurityPrefs(xsltPrefs, XSLT_SECPREF_WRITE_NETWORK) == xsltSecurityAllow ? Qtrue : Qfalse);
+  return prefs;
+}
+
 void
 noko_init_xslt_stylesheet(void)
 {
   rb_define_singleton_method(mNokogiriXslt, "register", rb_xslt_s_register, 2);
   rb_iv_set(mNokogiriXslt, "@modules", rb_hash_new());
 
   cNokogiriXsltStylesheet = rb_define_class_under(mNokogiriXslt, "Stylesheet", rb_cObject);
+  mNokogiriXsltSecurity = rb_define_module_under(mNokogiriXslt, "Security");
+  cNokogiriXsltSecurityConfig = rb_define_class_under(mNokogiriXsltSecurity, "Config", rb_cObject);
 
   rb_undef_alloc_func(cNokogiriXsltStylesheet);
 
   rb_define_singleton_method(cNokogiriXsltStylesheet, "parse_stylesheet_doc", parse_stylesheet_doc, 1);
+  rb_define_singleton_method(cNokogiriXsltStylesheet, "default_security_options", rb_get_default_security_options, 0);
+  rb_define_singleton_method(cNokogiriXsltStylesheet, "default_security_options=", rb_set_default_security_options, 1);
   rb_define_method(cNokogiriXsltStylesheet, "serialize", rb_xslt_stylesheet_serialize, 1);
   rb_define_method(cNokogiriXsltStylesheet, "transform", rb_xslt_stylesheet_transform, -1);
 }

lib/nokogiri/xslt.rb

@@ -1,6 +1,8 @@
 # coding: utf-8
 # frozen_string_literal: true
 
+require_relative "xslt/security"
+
 module Nokogiri
   class << self
     ###
@@ -19,6 +21,8 @@ def XSLT(stylesheet, modules = {})
   # See Nokogiri::XSLT::Stylesheet for creating and manipulating
   # Stylesheet object.
   module XSLT
+    include Nokogiri::XSLT::Security
+
     class << self
       # :call-seq:
       #   parse(xsl) → Nokogiri::XSLT::Stylesheet
@@ -86,6 +90,20 @@ def parse(string, modules = {})
         end
       end
 
+      ###
+      # Get the default security options used by libxslt
+      # [Returns] an object of type Nokogiri::XSLT::Security::Config
+      def default_security_options
+        Stylesheet.default_security_options
+      end
+
+      ###
+      # Set the default security options used by libxslt
+      # +options+ should be an object of type Nokogiri::XSLT::Security::Config
+      def default_security_options=(options)
+        Stylesheet.default_security_options=(options)
+      end
+
       # :call-seq:
       #   quote_params(params) → Array
       #

lib/nokogiri/xslt/security.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+module Nokogiri
+  module XSLT
+    module Security
+      class Config
+        attr_accessor :allow_read_file
+        attr_accessor :allow_write_file
+        attr_accessor :allow_create_directory
+        attr_accessor :allow_read_network
+        attr_accessor :allow_write_network
+
+        # Mirror xslt (implicit) internal defaults
+        def initialize
+          @allow_read_file = true
+          @allow_write_file = true
+          @allow_create_directory = true
+          @allow_read_network = true
+          @allow_write_network = true
+        end
+      end
+    end
+  end
+end

nokogiri.gemspec

@@ -301,6 +301,7 @@ Gem::Specification.new do |spec|
     "lib/nokogiri/xml/xpath/syntax_error.rb",
     "lib/nokogiri/xml/xpath_context.rb",
     "lib/nokogiri/xslt.rb",
+    "lib/nokogiri/xslt/security.rb",
     "lib/nokogiri/xslt/stylesheet.rb",
     "lib/xsd/xmlparser/nokogiri.rb",
   ]

test/files/xslt_included.xsl

@@ -0,0 +1,6 @@
+<?xml version='1.0' encoding="UTF-8"?>
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+  version='1.0'>
+  <xsl:output method="text" indent="no" encoding="UTF-8"/>
+
+</xsl:stylesheet>

test/files/xslt_including.xsl

@@ -0,0 +1,7 @@
+<?xml version='1.0' encoding="UTF-8"?>
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+  version='1.0'>
+  <xsl:output method="text" indent="no" encoding="UTF-8"/>
+
+  <xsl:include href="./xslt_included.xsl"/>
+</xsl:stylesheet>

test/helper.rb

@@ -77,6 +77,7 @@ module TestBase
     XML_XINCLUDE_FILE    = File.join(ASSETS_DIR, "xinclude.xml")
     XML_ATOM_FILE        = File.join(ASSETS_DIR, "atom.xml")
     XSLT_FILE            = File.join(ASSETS_DIR, "staff.xslt")
+    XSLT_INCLUDING_FILE  = File.join(ASSETS_DIR, "xslt_including.xsl")
     XPATH_FILE           = File.join(ASSETS_DIR, "slow-xpath.xml")
 
     def i_am_ruby_matching(gem_version_requirement_string)

test/test_xslt_transforms.rb

@@ -187,6 +187,95 @@ def test_transform_with_quote_params
         assert_equal("Booyah", result_doc.at_css("h1").content)
       end
 
+      def test_default_security_options_read_file
+        options = Nokogiri::XSLT::Security::Config.new
+
+        if Nokogiri.jruby?
+          assert_raises(NotImplementedError) do
+            Nokogiri::XSLT.default_security_options = options
+          end
+        else
+          # Default is insecure
+          Nokogiri::XSLT.default_security_options = options
+          assert(Nokogiri::XSLT(File.open(XSLT_INCLUDING_FILE)))
+
+          options.allow_read_file = false
+          Nokogiri::XSLT.default_security_options = options
+          assert_raises(RuntimeError) { Nokogiri::XSLT(File.open(XSLT_INCLUDING_FILE)) }
+
+          options.allow_read_file = true
+          Nokogiri::XSLT.default_security_options = options
+          assert(Nokogiri::XSLT(File.open(XSLT_INCLUDING_FILE)))
+        end
+      end
+
+      def test_default_security_options_roundtrip
+        options = Nokogiri::XSLT::Security::Config.new
+
+        if Nokogiri.jruby?
+          assert_raises(NotImplementedError) do
+            Nokogiri::XSLT.default_security_options
+          end
+        else
+          # Since the getter constructs the settings from the underlying C library
+          # this actually tells us if the settings are configured correctly
+          # Check all settings once per option to make sure fields are plumbed right
+          # at every stage
+          Nokogiri::XSLT.default_security_options = options
+          configured_opts = Nokogiri::XSLT.default_security_options
+          assert(configured_opts.allow_read_file)
+          assert(configured_opts.allow_write_file)
+          assert(configured_opts.allow_create_directory)
+          assert(configured_opts.allow_read_network)
+          assert(configured_opts.allow_write_network)
+
+          options.allow_read_file = false
+          Nokogiri::XSLT.default_security_options = options
+          configured_opts = Nokogiri::XSLT.default_security_options
+          refute(configured_opts.allow_read_file)
+          assert(configured_opts.allow_write_file)
+          assert(configured_opts.allow_create_directory)
+          assert(configured_opts.allow_read_network)
+          assert(configured_opts.allow_write_network)
+
+          options.allow_write_file = false
+          Nokogiri::XSLT.default_security_options = options
+          configured_opts = Nokogiri::XSLT.default_security_options
+          refute(configured_opts.allow_read_file)
+          refute(configured_opts.allow_write_file)
+          assert(configured_opts.allow_create_directory)
+          assert(configured_opts.allow_read_network)
+          assert(configured_opts.allow_write_network)
+
+          options.allow_create_directory = false
+          Nokogiri::XSLT.default_security_options = options
+          configured_opts = Nokogiri::XSLT.default_security_options
+          refute(configured_opts.allow_read_file)
+          refute(configured_opts.allow_write_file)
+          refute(configured_opts.allow_create_directory)
+          assert(configured_opts.allow_read_network)
+          assert(configured_opts.allow_write_network)
+
+          options.allow_read_network = false
+          Nokogiri::XSLT.default_security_options = options
+          configured_opts = Nokogiri::XSLT.default_security_options
+          refute(configured_opts.allow_read_file)
+          refute(configured_opts.allow_write_file)
+          refute(configured_opts.allow_create_directory)
+          refute(configured_opts.allow_read_network)
+          assert(configured_opts.allow_write_network)
+
+          options.allow_write_network = false
+          Nokogiri::XSLT.default_security_options = options
+          configured_opts = Nokogiri::XSLT.default_security_options
+          refute(configured_opts.allow_read_file)
+          refute(configured_opts.allow_write_file)
+          refute(configured_opts.allow_create_directory)
+          refute(configured_opts.allow_read_network)
+          refute(configured_opts.allow_write_network)
+        end
+      end
+
       def test_exslt
         # see http://yokolet.blogspot.com/2010/10/pure-java-nokogiri-xslt-extension.html")
         skip_unless_libxml2("cannot get it working on JRuby")