Import and abstract the regparser library to provide offline parsin…

…g of the Windows registry.

This abstraction makes testing easier and provide a path for offline parsing of Windows images.

PiperOrigin-RevId: 676808177

common/windows/registry/offline.go

@@ -0,0 +1,122 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package registry
+
+import (
+	"errors"
+	"io"
+	"os"
+
+	"www.velocidex.com/golang/regparser"
+)
+
+var (
+	errFailedToReadClassName = errors.New("failed to read class name")
+)
+
+// OfflineRegistry wraps the regparser library to provide offline (from file) parsing of the Windows
+// registry.
+type OfflineRegistry struct {
+	registry *regparser.Registry
+	reader   io.ReadCloser
+}
+
+// NewFromFile creates a new offline registry abstraction from a file.
+func NewFromFile(path string) (*OfflineRegistry, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+
+	reg, err := regparser.NewRegistry(f)
+	if err != nil {
+		f.Close()
+		return nil, err
+	}
+
+	return &OfflineRegistry{reg, f}, nil
+}
+
+// OpenKey open the requested registry key.
+func (o *OfflineRegistry) OpenKey(path string) Key {
+	return &OfflineKey{o.registry.OpenKey(path)}
+}
+
+// Close closes the underlying reader.
+func (o *OfflineRegistry) Close() error {
+	return o.reader.Close()
+}
+
+// OfflineKey wraps a regparser.CM_KEY_NODE to provide an implementation of the registry.Key
+// interface.
+type OfflineKey struct {
+	key *regparser.CM_KEY_NODE
+}
+
+// Name returns the name of the key.
+func (o *OfflineKey) Name() string {
+	return o.key.Name()
+}
+
+// Subkeys returns the subkeys of the key.
+func (o *OfflineKey) Subkeys() []Key {
+	var subkeys []Key
+	for _, subkey := range o.key.Subkeys() {
+		subkeys = append(subkeys, &OfflineKey{subkey})
+	}
+
+	return subkeys
+}
+
+// ClassName returns the class name of the key.
+func (o *OfflineKey) ClassName() ([]byte, error) {
+	// retrieve the class name offset and skip both the first block and the first 4 bytes that
+	// represents the size of the block.
+	classOffset := int64(o.key.Class()) + 4096 + 4
+	classLen := o.key.ClassLength()
+	buffer := make([]byte, classLen)
+
+	if n, err := o.key.Reader.ReadAt(buffer, classOffset); err != nil || n != int(classLen) {
+		return nil, errFailedToReadClassName
+	}
+
+	return buffer, nil
+}
+
+// Values returns the different values contained in the key.
+func (o *OfflineKey) Values() []Value {
+	var values []Value
+	for _, value := range o.key.Values() {
+		values = append(values, &OfflineValue{value})
+	}
+
+	return values
+}
+
+// OfflineValue wraps a regparser.CM_KEY_VALUE to provide an implementation of the registry.Value
+// interface.
+type OfflineValue struct {
+	value *regparser.CM_KEY_VALUE
+}
+
+// Name returns the name of the value.
+func (o *OfflineValue) Name() string {
+	return o.value.ValueName()
+}
+
+// Data returns the data contained in the value.
+func (o *OfflineValue) Data() []byte {
+	return o.value.ValueData().Data
+}

common/windows/registry/registry.go

@@ -0,0 +1,51 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package registry provides an interface to abstract the Windows registry libraries away.
+// This allows providing more functionalities to registry libraries and also provide a better means
+// of testing.
+package registry
+
+// Registry represents an open registry hive.
+type Registry interface {
+	// OpenKey returns a Key for the given path.
+	OpenKey(path string) Key
+
+	// Close closes the registry hive.
+	Close() error
+}
+
+// Key represents a specific registry key.
+type Key interface {
+	// Name returns the name of the key.
+	Name() string
+
+	// ClassName returns the name of the class for the key.
+	ClassName() ([]byte, error)
+
+	// Subkeys returns the subkeys of the key.
+	Subkeys() []Key
+
+	// Values returns the different values of the key.
+	Values() []Value
+}
+
+// Value represents a value inside a specific key.
+type Value interface {
+	// Name returns the name of the value.
+	Name() string
+
+	// Data returns the data of the value.
+	Data() []byte
+}

go.mod

@@ -44,6 +44,7 @@ require (
 	github.com/containerd/stargz-snapshotter/estargz v0.15.1 // indirect
 	github.com/containerd/ttrpc v1.2.4 // indirect
 	github.com/containerd/typeurl/v2 v2.1.1 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/docker/cli v25.0.3+incompatible // indirect
 	github.com/docker/distribution v2.8.3+incompatible // indirect
 	github.com/docker/docker v25.0.6+incompatible // indirect
@@ -81,4 +82,5 @@ require (
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20240304212257-790db918fca8 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 	sigs.k8s.io/yaml v1.4.0 // indirect
+	www.velocidex.com/golang/regparser v0.0.0-20240404115756-2169ac0e3c09 // indirect
 )

go.sum

@@ -327,3 +327,5 @@ modernc.org/sqlite v1.20.3/go.mod h1:zKcGyrICaxNTMEHSr1HQ2GUraP0j+845GYw37+EyT6A
 sigs.k8s.io/yaml v1.3.0/go.mod h1:GeOyir5tyXNByN85N/dRIT9es5UQNerPYEKK56eTBm8=
 sigs.k8s.io/yaml v1.4.0 h1:Mk1wCc2gy/F0THH0TAp1QYyJNzRm2KCLy3o5ASXVI5E=
 sigs.k8s.io/yaml v1.4.0/go.mod h1:Ejl7/uTz7PSA4eKMyQCUTnhZYNmLIl+5c2lQPGR2BPY=
+www.velocidex.com/golang/regparser v0.0.0-20240404115756-2169ac0e3c09 h1:G1RWYBXP2lSzxKcrAU1YhiUlBetZ7hGIzIiWuuazvfo=
+www.velocidex.com/golang/regparser v0.0.0-20240404115756-2169ac0e3c09/go.mod h1:pxSECT5mWM3goJ4sxB4HCJNKnKqiAlpyT8XnvBwkLGU=

testing/mockregistry/mockregistry.go

@@ -0,0 +1,89 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package mockregistry provides a mock implementation of the registry.Registry interface.
+package mockregistry
+
+import (
+	"errors"
+
+	"github.com/google/osv-scalibr/common/windows/registry"
+)
+
+var (
+	errFailedToReadClassName = errors.New("failed to read class name")
+)
+
+// MockRegistry mocks registry access.
+type MockRegistry struct {
+	Keys map[string]registry.Key
+}
+
+// OpenKey open the requested registry key.
+func (o *MockRegistry) OpenKey(path string) registry.Key {
+	if key, ok := o.Keys[path]; ok {
+		return key
+	}
+
+	return nil
+}
+
+// Close does nothing when mocking.
+func (o *MockRegistry) Close() error {
+	return nil
+}
+
+// MockKey mocks a registry.Key.
+type MockKey struct {
+	KName      string
+	KClassName string
+	KSubkeys   []registry.Key
+	KValues    []registry.Value
+}
+
+// Name returns the name of the key.
+func (o *MockKey) Name() string {
+	return o.KName
+}
+
+// Subkeys returns the subkeys of the key.
+func (o *MockKey) Subkeys() []registry.Key {
+	return o.KSubkeys
+}
+
+// ClassName returns the class name of the key.
+func (o *MockKey) ClassName() ([]byte, error) {
+	return []byte(o.KClassName), nil
+}
+
+// Values returns the different values contained in the key.
+func (o *MockKey) Values() []registry.Value {
+	return o.KValues
+}
+
+// MockValue mocks a registry.Value.
+type MockValue struct {
+	VName string
+	VData []byte
+}
+
+// Name returns the name of the value.
+func (o *MockValue) Name() string {
+	return o.VName
+}
+
+// Data returns the data contained in the value.
+func (o *MockValue) Data() []byte {
+	return o.VData
+}