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https://github.com/token2/snapd.git
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eca4743411
* secboot: switch encryption key size to 32 byte (thanks to Chris) We are using an incorrect size for encryption key in secboot. Chris mentioned this a while ago and this commit fixes it and moves to a 32 byte key instead of the 64 byte key. * tests: update uc20-create-partitions-encrypt test to match new keysize
119 lines
3.3 KiB
Go
119 lines
3.3 KiB
Go
// -*- Mode: Go; indent-tabs-mode: t -*-
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/*
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* Copyright (C) 2021 Canonical Ltd
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 3 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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package secboot
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import (
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"crypto/rand"
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"fmt"
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"io"
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"os"
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"path/filepath"
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"github.com/snapcore/snapd/osutil"
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)
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const (
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// The encryption key size is set so it has the same entropy as the derived
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// key.
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encryptionKeySize = 32
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// XXX: needs to be in sync with
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// github.com/snapcore/secboot/crypto.go:"type RecoveryKey"
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// Size of the recovery key.
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recoveryKeySize = 16
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// The auxiliary key is used to bind keys to models
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auxKeySize = 32
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)
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// used in tests
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var randRead = rand.Read
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// EncryptionKey is the key used to encrypt the data partition.
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type EncryptionKey []byte
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func NewEncryptionKey() (EncryptionKey, error) {
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key := make(EncryptionKey, encryptionKeySize)
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// rand.Read() is protected against short reads
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_, err := randRead(key[:])
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// On return, n == len(b) if and only if err == nil
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return key, err
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}
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// Save writes the key in the location specified by filename.
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func (key EncryptionKey) Save(filename string) error {
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if err := os.MkdirAll(filepath.Dir(filename), 0755); err != nil {
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return err
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}
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return osutil.AtomicWriteFile(filename, key[:], 0600, 0)
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}
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// RecoveryKey is a key used to unlock the encrypted partition when
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// the encryption key can't be used, for example when unseal fails.
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type RecoveryKey [recoveryKeySize]byte
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func NewRecoveryKey() (RecoveryKey, error) {
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var key RecoveryKey
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// rand.Read() is protected against short reads
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_, err := randRead(key[:])
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// On return, n == len(b) if and only if err == nil
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return key, err
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}
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// Save writes the recovery key in the location specified by filename.
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func (key RecoveryKey) Save(filename string) error {
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if err := os.MkdirAll(filepath.Dir(filename), 0755); err != nil {
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return err
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}
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return osutil.AtomicWriteFile(filename, key[:], 0600, 0)
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}
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func RecoveryKeyFromFile(recoveryKeyFile string) (*RecoveryKey, error) {
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f, err := os.Open(recoveryKeyFile)
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if err != nil {
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return nil, fmt.Errorf("cannot open recovery key: %v", err)
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}
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defer f.Close()
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st, err := f.Stat()
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if err != nil {
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return nil, fmt.Errorf("cannot stat recovery key: %v", err)
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}
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if st.Size() != int64(len(RecoveryKey{})) {
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return nil, fmt.Errorf("cannot read recovery key: unexpected size %v for the recovery key file %s", st.Size(), recoveryKeyFile)
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}
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var rkey RecoveryKey
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if _, err := io.ReadFull(f, rkey[:]); err != nil {
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return nil, fmt.Errorf("cannot read recovery key: %v", err)
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}
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return &rkey, nil
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}
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// AuxKey is the key to bind models to keys.
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type AuxKey [auxKeySize]byte
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func NewAuxKey() (AuxKey, error) {
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var key AuxKey
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// rand.Read() is protected against short reads
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_, err := randRead(key[:])
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// On return, n == len(b) if and only if err == nil
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return key, err
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}
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