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/*
* checks.go - Some sanity check methods for our metadata structures
*
* Copyright 2017 Google Inc.
* Author: Joe Richey (joerichey@google.com)
*
* 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 metadata
import (
"github.com/golang/protobuf/proto"
"github.com/pkg/errors"
"github.com/google/fscrypt/util"
)
var errNotInitialized = errors.New("not initialized")
// Metadata is the interface to all of the protobuf structures that can be
// checked for validity.
type Metadata interface {
CheckValidity() error
proto.Message
}
// CheckValidity ensures the mode has a name and isn't empty.
func (m EncryptionOptions_Mode) CheckValidity() error {
if m == EncryptionOptions_default {
return errNotInitialized
}
if m.String() == "" {
return errors.Errorf("unknown %d", m)
}
return nil
}
// CheckValidity ensures the source has a name and isn't empty.
func (s SourceType) CheckValidity() error {
if s == SourceType_default {
return errNotInitialized
}
if s.String() == "" {
return errors.Errorf("unknown %d", s)
}
return nil
}
// CheckValidity ensures the hash costs will be accepted by Argon2.
func (h *HashingCosts) CheckValidity() error {
if h == nil {
return errNotInitialized
}
if h.Time <= 0 {
return errors.Errorf("time=%d is not positive", h.Time)
}
if h.Parallelism <= 0 {
return errors.Errorf("parallelism=%d is not positive", h.Parallelism)
}
minMemory := 8 * h.Parallelism
if h.Memory < minMemory {
return errors.Errorf("memory=%d is less than minimum (%d)", h.Memory, minMemory)
}
return nil
}
// CheckValidity ensures our buffers are the correct length.
func (w *WrappedKeyData) CheckValidity() error {
if w == nil {
return errNotInitialized
}
if len(w.EncryptedKey) == 0 {
return errors.Wrap(errNotInitialized, "encrypted key")
}
if err := util.CheckValidLength(IVLen, len(w.IV)); err != nil {
return errors.Wrap(err, "IV")
}
return errors.Wrap(util.CheckValidLength(HMACLen, len(w.Hmac)), "HMAC")
}
// CheckValidity ensures our ProtectorData has the correct fields for its source.
func (p *ProtectorData) CheckValidity() error {
if p == nil {
return errNotInitialized
}
if err := p.Source.CheckValidity(); err != nil {
return errors.Wrap(err, "protector source")
}
// Source specific checks
switch p.Source {
case SourceType_pam_passphrase:
if p.Uid < 0 {
return errors.Errorf("UID=%d is negative", p.Uid)
}
fallthrough
case SourceType_custom_passphrase:
if err := p.Costs.CheckValidity(); err != nil {
return errors.Wrap(err, "passphrase hashing costs")
}
if err := util.CheckValidLength(SaltLen, len(p.Salt)); err != nil {
return errors.Wrap(err, "passphrase hashing salt")
}
}
// Generic checks
if err := p.WrappedKey.CheckValidity(); err != nil {
return errors.Wrap(err, "wrapped protector key")
}
if err := util.CheckValidLength(DescriptorLen, len(p.ProtectorDescriptor)); err != nil {
return errors.Wrap(err, "protector descriptor")
}
err := util.CheckValidLength(InternalKeyLen, len(p.WrappedKey.EncryptedKey))
return errors.Wrap(err, "encrypted protector key")
}
// CheckValidity ensures each of the options is valid.
func (e *EncryptionOptions) CheckValidity() error {
if e == nil {
return errNotInitialized
}
if _, ok := util.Index(e.Padding, paddingArray); !ok {
return errors.Errorf("padding of %d is invalid", e.Padding)
}
if err := e.Contents.CheckValidity(); err != nil {
return errors.Wrap(err, "contents encryption mode")
}
return errors.Wrap(e.Filenames.CheckValidity(), "filenames encryption mode")
}
// CheckValidity ensures the fields are valid and have the correct lengths.
func (w *WrappedPolicyKey) CheckValidity() error {
if w == nil {
return errNotInitialized
}
if err := w.WrappedKey.CheckValidity(); err != nil {
return errors.Wrap(err, "wrapped key")
}
if err := util.CheckValidLength(PolicyKeyLen, len(w.WrappedKey.EncryptedKey)); err != nil {
return errors.Wrap(err, "encrypted key")
}
err := util.CheckValidLength(DescriptorLen, len(w.ProtectorDescriptor))
return errors.Wrap(err, "wrapping protector descriptor")
}
// CheckValidity ensures the fields and each wrapped key are valid.
func (p *PolicyData) CheckValidity() error {
if p == nil {
return errNotInitialized
}
// Check each wrapped key
for i, w := range p.WrappedPolicyKeys {
if err := w.CheckValidity(); err != nil {
return errors.Wrapf(err, "policy key slot %d", i)
}
}
if err := util.CheckValidLength(DescriptorLen, len(p.KeyDescriptor)); err != nil {
return errors.Wrap(err, "policy key descriptor")
}
return errors.Wrap(p.Options.CheckValidity(), "policy options")
}
// CheckValidity ensures the Config has all the necessary info for its Source.
func (c *Config) CheckValidity() error {
// General checks
if c == nil {
return errNotInitialized
}
if err := c.Source.CheckValidity(); err != nil {
return errors.Wrap(err, "default config source")
}
// Source specific checks
switch c.Source {
case SourceType_pam_passphrase, SourceType_custom_passphrase:
if err := c.HashCosts.CheckValidity(); err != nil {
return errors.Wrap(err, "config hashing costs")
}
}
return errors.Wrap(c.Options.CheckValidity(), "config options")
}
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