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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 (
"log"
"github.com/golang/protobuf/proto"
"fscrypt/util"
)
// Metadata is the interface to all of the protobuf structures that can be
// checked with the IsValid method.
type Metadata interface {
IsValid() bool
proto.Message
}
// checkValidLength returns true if expected == actual, otherwise it logs an
// InvalidLengthError.
func checkValidLength(name string, expected int, actual int) bool {
if expected != actual {
log.Print(util.InvalidLengthError(name, expected, actual))
return false
}
return true
}
// IsValid ensures the mode has a name and isn't empty.
func (m EncryptionOptions_Mode) IsValid() bool {
if m.String() == "" {
log.Print("Encryption mode cannot be the empty string")
return false
}
if m == EncryptionOptions_default {
log.Print("Encryption mode must be set to a non-default value")
return false
}
return true
}
// IsValid ensures the source has a name and isn't empty.
func (s SourceType) IsValid() bool {
if s.String() == "" {
log.Print("SourceType cannot be the empty string")
return false
}
if s == SourceType_default {
log.Print("SourceType must be set to a non-default value")
return false
}
return true
}
// IsValid ensures the hash costs will be accepted by Argon2.
func (h *HashingCosts) IsValid() bool {
if h == nil {
log.Print("HashingCosts not initialized")
return false
}
if h.Time == 0 {
log.Print("Hashing time cost not initialized")
return false
}
if h.Parallelism == 0 {
log.Print("Hashing parallelism cost not initialized")
return false
}
minMemory := 8 * h.Parallelism
if h.Memory < minMemory {
log.Printf("Hashing memory cost must be at least %d", minMemory)
return false
}
return true
}
// IsValid ensures our buffers are the correct length (or just exist).
func (w *WrappedKeyData) IsValid() bool {
if w == nil {
log.Print("WrappedKeyData not initialized")
return false
}
if len(w.EncryptedKey) == 0 {
log.Print("EncryptedKey not initialized")
return false
}
return checkValidLength("IV", IVLen, len(w.IV)) &&
checkValidLength("HMAC", HMACLen, len(w.Hmac))
}
// IsValid ensures our ProtectorData has the correct fields for its source.
func (p *ProtectorData) IsValid() bool {
if p == nil {
log.Print("ProtectorData not initialized")
return false
}
// Source specific checks
switch p.Source {
case SourceType_pam_passphrase:
if p.Uid < 0 {
log.Print("The UID should never be negative")
return false
}
fallthrough
case SourceType_custom_passphrase:
if !p.Costs.IsValid() || !checkValidLength("Salt", SaltLen, len(p.Salt)) {
return false
}
}
// Generic checks
return p.Source.IsValid() &&
p.WrappedKey.IsValid() &&
checkValidLength("EncryptedKey", InternalKeyLen, len(p.WrappedKey.EncryptedKey)) &&
checkValidLength("ProtectorDescriptor", DescriptorLen, len(p.ProtectorDescriptor))
}
// IsValid ensures each of the options is valid.
func (e *EncryptionOptions) IsValid() bool {
if e == nil {
log.Print("EncryptionOptions not initialized")
return false
}
if _, ok := util.Index(e.Padding, paddingArray); !ok {
log.Printf("Padding of %d is invalid", e.Padding)
return false
}
return e.Contents.IsValid() && e.Filenames.IsValid()
}
// IsValid ensures the fields are valid and have the correct lengths.
func (w *WrappedPolicyKey) IsValid() bool {
if w == nil {
log.Print("WrappedPolicyKey not initialized")
return false
}
return w.WrappedKey.IsValid() &&
checkValidLength("EncryptedKey", PolicyKeyLen, len(w.WrappedKey.EncryptedKey)) &&
checkValidLength("ProtectorDescriptor", DescriptorLen, len(w.ProtectorDescriptor))
}
// IsValid ensures the fields and each wrapped key are valid.
func (p *PolicyData) IsValid() bool {
if p == nil {
log.Print("PolicyData not initialized")
return false
}
// Check each wrapped key
for _, w := range p.WrappedPolicyKeys {
if !w.IsValid() {
return false
}
}
return p.Options.IsValid() &&
checkValidLength("KeyDescriptor", DescriptorLen, len(p.KeyDescriptor))
}
// IsValid ensures the Config has all the necessary info for its Source.
func (c *Config) IsValid() bool {
// General checks
if c == nil {
log.Print("Config not initialized")
return false
}
if !c.Source.IsValid() || !c.Options.IsValid() {
return false
}
// Source specific checks
switch c.Source {
case SourceType_pam_passphrase, SourceType_custom_passphrase:
return c.HashCosts.IsValid()
default:
return true
}
}
|
