Filter sensitive query string parameters in the log [#6244 state:committed]

This provides more safety to applications that put secret information in the query string, such as API keys or SSO tokens.

Signed-off-by: Xavier Noria <fxn@hashref.com>

3 files changed, 57 insertions, 4 deletions

diff --git a/actionpack/CHANGELOG b/actionpack/CHANGELOG
index d9fe45d897..5ab92c8cfc 100644
--- a/actionpack/CHANGELOG
+++ b/actionpack/CHANGELOG
@@ -1,5 +1,7 @@
 *Rails 3.1.0 (unreleased)*
 
+* Sensitive query string parameters (specified in config.filter_parameters) will now be filtered out from the request paths in the log file. [Prem Sichanugrist, fxn]
+
 * URL parameters which return false for to_param now appear in the query string (previously they were removed) [Andrew White]
 
 * URL parameters which return nil for to_param are now removed from the query string [Andrew White]
diff --git a/actionpack/lib/action_dispatch/http/filter_parameters.rb b/actionpack/lib/action_dispatch/http/filter_parameters.rb
index 1ab48ae04d..8dd1af7f3d 100644
--- a/actionpack/lib/action_dispatch/http/filter_parameters.rb
+++ b/actionpack/lib/action_dispatch/http/filter_parameters.rb
@@ -5,10 +5,10 @@ require 'active_support/core_ext/object/duplicable'
 module ActionDispatch
   module Http
     # Allows you to specify sensitive parameters which will be replaced from
-    # the request log by looking in all subhashes of the param hash for keys
-    # to filter. If a block is given, each key and value of the parameter
-    # hash and all subhashes is passed to it, the value or key can be replaced
-    # using String#replace or similar method.
+    # the request log by looking in the query string of the request and all
+    # subhashes of the params hash to filter. If a block is given, each key and
+    # value of the params hash and all subhashes is passed to it, the value
+    # or key can be replaced using String#replace or similar method.
     #
     # Examples:
     #
@@ -38,6 +38,11 @@ module ActionDispatch
         @filtered_env ||= env_filter.filter(@env)
       end
 
+      # Reconstructed a path with all sensitive GET parameters replaced.
+      def filtered_path
+        @filtered_path ||= query_string.empty? ? path : "#{path}?#{filtered_query_string}"
+      end
+
     protected
 
       def parameter_filter
@@ -52,6 +57,14 @@ module ActionDispatch
         @@parameter_filter_for[filters] ||= ParameterFilter.new(filters)
       end
 
+      KV_RE   = '[^&;=]+'
+      PAIR_RE = %r{(#{KV_RE})=(#{KV_RE})}
+      def filtered_query_string
+        query_string.gsub(PAIR_RE) do |_|
+          parameter_filter.filter([[$1, $2]]).first.join("=")
+        end
+      end
+
     end
   end
 end
diff --git a/actionpack/test/dispatch/request_test.rb b/actionpack/test/dispatch/request_test.rb
index dd5bf5ec2d..f03ae7f2b3 100644
--- a/actionpack/test/dispatch/request_test.rb
+++ b/actionpack/test/dispatch/request_test.rb
@@ -518,6 +518,44 @@ class RequestTest < ActiveSupport::TestCase
     assert_equal "1", request.params["step"]
   end
 
+  test "filtered_path returns path with filtered query string" do
+    %w(; &).each do |sep|
+      request = stub_request('QUERY_STRING' => %w(username=sikachu secret=bd4f21f api_key=b1bc3b3cd352f68d79d7).join(sep),
+        'PATH_INFO' => '/authenticate',
+        'action_dispatch.parameter_filter' => [:secret, :api_key])
+
+      path = request.filtered_path
+      assert_equal %w(/authenticate?username=sikachu secret=[FILTERED] api_key=[FILTERED]).join(sep), path
+    end
+  end
+
+  test "filtered_path should not unescape a genuine '[FILTERED]' value" do
+    request = stub_request('QUERY_STRING' => "secret=bd4f21f&genuine=%5BFILTERED%5D",
+      'PATH_INFO' => '/authenticate',
+      'action_dispatch.parameter_filter' => [:secret])
+
+    path = request.filtered_path
+    assert_equal "/authenticate?secret=[FILTERED]&genuine=%5BFILTERED%5D", path
+  end
+
+  test "filtered_path should preserve duplication of keys in query string" do
+    request = stub_request('QUERY_STRING' => "username=sikachu&secret=bd4f21f&username=fxn",
+      'PATH_INFO' => '/authenticate',
+      'action_dispatch.parameter_filter' => [:secret])
+
+    path = request.filtered_path
+    assert_equal "/authenticate?username=sikachu&secret=[FILTERED]&username=fxn", path
+  end
+
+  test "filtered_path should ignore searchparts" do
+    request = stub_request('QUERY_STRING' => "secret",
+      'PATH_INFO' => '/authenticate',
+      'action_dispatch.parameter_filter' => [:secret])
+
+    path = request.filtered_path
+    assert_equal "/authenticate?secret", path
+  end
+
 protected
 
   def stub_request(env = {})