[ruby/psych] Introduce `Psych.unsafe_load`

In future versions of Psych, the `load` method will be mostly the same
as the `safe_load` method.  In other words, the `load` method won't
allow arbitrary object deserialization (which can be used to escalate to
an RCE).  People that need to load *trusted* documents can use the
`unsafe_load` method.

This commit introduces the `unsafe_load` method so that people can
incrementally upgrade.  For example, if they try to upgrade to 4.0.0 and
something breaks, they can downgrade, audit callsites, change to
`safe_load` or `unsafe_load` as required, and then upgrade to 4.0.0
smoothly.

https://github.com/ruby/psych/commit/cb50aa8d3f

1 files changed, 8 insertions, 4 deletions

diff --git a/test/psych/test_object_references.rb b/test/psych/test_object_references.rb
index ca69c7d288..269d72242e 100644
--- a/test/psych/test_object_references.rb
+++ b/test/psych/test_object_references.rb
@@ -34,12 +34,16 @@ module Psych
     def assert_reference_trip obj
       yml = Psych.dump([obj, obj])
       assert_match(/\*-?\d+/, yml)
-      data = Psych.load yml
+      begin
+        data = Psych.load yml
+      rescue Psych::DisallowedClass
+        data = Psych.unsafe_load yml
+      end
       assert_equal data.first.object_id, data.last.object_id
     end
 
     def test_float_references
-      data = Psych.load <<-eoyml
+      data = Psych.unsafe_load <<-eoyml
 ---\s
 - &name 1.2
 - *name
@@ -49,7 +53,7 @@ module Psych
     end
 
     def test_binary_references
-      data = Psych.load <<-eoyml
+      data = Psych.unsafe_load <<-eoyml
 ---
 - &name !binary |-
   aGVsbG8gd29ybGQh
@@ -60,7 +64,7 @@ module Psych
     end
 
     def test_regexp_references
-      data = Psych.load <<-eoyml
+      data = Psych.unsafe_load <<-eoyml
 ---\s
 - &name !ruby/regexp /pattern/i
 - *name