/
cmd_initramfs_mounts.go
1412 lines (1255 loc) · 50.7 KB
/
cmd_initramfs_mounts.go
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// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2019-2020 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package main
import (
"crypto/subtle"
"encoding/json"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"strings"
"syscall"
"github.com/jessevdk/go-flags"
"github.com/snapcore/snapd/asserts"
"github.com/snapcore/snapd/boot"
"github.com/snapcore/snapd/dirs"
"github.com/snapcore/snapd/logger"
"github.com/snapcore/snapd/osutil"
"github.com/snapcore/snapd/osutil/disks"
"github.com/snapcore/snapd/overlord/state"
"github.com/snapcore/snapd/secboot"
"github.com/snapcore/snapd/snap"
"github.com/snapcore/snapd/snap/squashfs"
"github.com/snapcore/snapd/sysconfig"
// to set sysconfig.ApplyFilesystemOnlyDefaultsImpl
_ "github.com/snapcore/snapd/overlord/configstate/configcore"
)
func init() {
const (
short = "Generate mounts for the initramfs"
long = "Generate and perform all mounts for the initramfs before transitioning to userspace"
)
addCommandBuilder(func(parser *flags.Parser) {
if _, err := parser.AddCommand("initramfs-mounts", short, long, &cmdInitramfsMounts{}); err != nil {
panic(err)
}
})
snap.SanitizePlugsSlots = func(*snap.Info) {}
}
type cmdInitramfsMounts struct{}
func (c *cmdInitramfsMounts) Execute(args []string) error {
return generateInitramfsMounts()
}
var (
osutilIsMounted = osutil.IsMounted
snapTypeToMountDir = map[snap.Type]string{
snap.TypeBase: "base",
snap.TypeKernel: "kernel",
snap.TypeSnapd: "snapd",
}
secbootMeasureSnapSystemEpochWhenPossible func() error
secbootMeasureSnapModelWhenPossible func(findModel func() (*asserts.Model, error)) error
secbootUnlockVolumeUsingSealedKeyIfEncrypted func(disk disks.Disk, name string, encryptionKeyFile string, opts *secboot.UnlockVolumeUsingSealedKeyOptions) (secboot.UnlockResult, error)
secbootUnlockEncryptedVolumeUsingKey func(disk disks.Disk, name string, key []byte) (secboot.UnlockResult, error)
secbootLockSealedKeys func() error
bootFindPartitionUUIDForBootedKernelDisk = boot.FindPartitionUUIDForBootedKernelDisk
)
func stampedAction(stamp string, action func() error) error {
stampFile := filepath.Join(dirs.SnapBootstrapRunDir, stamp)
if osutil.FileExists(stampFile) {
return nil
}
if err := os.MkdirAll(filepath.Dir(stampFile), 0755); err != nil {
return err
}
if err := action(); err != nil {
return err
}
return ioutil.WriteFile(stampFile, nil, 0644)
}
func generateInitramfsMounts() (err error) {
// ensure that the last thing we do is to lock access to sealed keys,
// regardless of mode or early failures.
defer func() {
if e := secbootLockSealedKeys(); e != nil {
e = fmt.Errorf("error locking access to sealed keys: %v", e)
if err == nil {
err = e
} else {
// preserve err but log
logger.Noticef("%v", e)
}
}
}()
// Ensure there is a very early initial measurement
err = stampedAction("secboot-epoch-measured", func() error {
return secbootMeasureSnapSystemEpochWhenPossible()
})
if err != nil {
return err
}
mode, recoverySystem, err := boot.ModeAndRecoverySystemFromKernelCommandLine()
if err != nil {
return err
}
mst := &initramfsMountsState{
mode: mode,
recoverySystem: recoverySystem,
}
switch mode {
case "recover":
return generateMountsModeRecover(mst)
case "install":
return generateMountsModeInstall(mst)
case "run":
return generateMountsModeRun(mst)
}
// this should never be reached
return fmt.Errorf("internal error: mode in generateInitramfsMounts not handled")
}
// generateMountsMode* is called multiple times from initramfs until it
// no longer generates more mount points and just returns an empty output.
func generateMountsModeInstall(mst *initramfsMountsState) error {
// steps 1 and 2 are shared with recover mode
model, snaps, err := generateMountsCommonInstallRecover(mst)
if err != nil {
return err
}
// 3. final step: write modeenv to tmpfs data dir and disable cloud-init in
// install mode
modeEnv, err := mst.EphemeralModeenvForModel(model, snaps)
if err != nil {
return err
}
if err := modeEnv.WriteTo(boot.InitramfsWritableDir); err != nil {
return err
}
// done, no output, no error indicates to initramfs we are done with
// mounting stuff
return nil
}
// copyNetworkConfig copies the network configuration to the target
// directory. This is used to copy the network configuration
// data from a real uc20 ubuntu-data partition into a ephemeral one.
func copyNetworkConfig(src, dst string) error {
for _, globEx := range []string{
// for network configuration setup by console-conf, etc.
// TODO:UC20: we want some way to "try" or "verify" the network
// configuration or to only use known-to-be-good network
// configuration i.e. from ubuntu-save before installing it
// onto recover mode, because the network configuration could
// have been what was broken so we don't want to break
// network configuration for recover mode as well, but for
// now this is fine
"system-data/etc/netplan/*",
// etc/machine-id is part of what systemd-networkd uses to generate a
// DHCP clientid (the other part being the interface name), so to have
// the same IP addresses across run mode and recover mode, we need to
// also copy the machine-id across
"system-data/etc/machine-id",
} {
if err := copyFromGlobHelper(src, dst, globEx); err != nil {
return err
}
}
return nil
}
// copyUbuntuDataMisc copies miscellaneous other files from the run mode system
// to the recover system such as:
// - timesync clock to keep the same time setting in recover as in run mode
func copyUbuntuDataMisc(src, dst string) error {
for _, globEx := range []string{
// systemd's timesync clock file so that the time in recover mode moves
// forward to what it was in run mode
// NOTE: we don't sync back the time movement from recover mode to run
// mode currently, unclear how/when we could do this, but recover mode
// isn't meant to be long lasting and as such it's probably not a big
// problem to "lose" the time spent in recover mode
"system-data/var/lib/systemd/timesync/clock",
} {
if err := copyFromGlobHelper(src, dst, globEx); err != nil {
return err
}
}
return nil
}
// copyUbuntuDataAuth copies the authentication files like
// - extrausers passwd,shadow etc
// - sshd host configuration
// - user .ssh dir
// to the target directory. This is used to copy the authentication
// data from a real uc20 ubuntu-data partition into a ephemeral one.
func copyUbuntuDataAuth(src, dst string) error {
for _, globEx := range []string{
"system-data/var/lib/extrausers/*",
"system-data/etc/ssh/*",
"user-data/*/.ssh/*",
// this ensures we get proper authentication to snapd from "snap"
// commands in recover mode
"user-data/*/.snap/auth.json",
// this ensures we also get non-ssh enabled accounts copied
"user-data/*/.profile",
// so that users have proper perms, i.e. console-conf added users are
// sudoers
"system-data/etc/sudoers.d/*",
} {
if err := copyFromGlobHelper(src, dst, globEx); err != nil {
return err
}
}
// ensure the user state is transferred as well
srcState := filepath.Join(src, "system-data/var/lib/snapd/state.json")
dstState := filepath.Join(dst, "system-data/var/lib/snapd/state.json")
err := state.CopyState(srcState, dstState, []string{"auth.users", "auth.macaroon-key", "auth.last-id"})
if err != nil && err != state.ErrNoState {
return fmt.Errorf("cannot copy user state: %v", err)
}
return nil
}
// copySafeDefaultData will copy to the destination a "safe" set of data for
// a blank recover mode, i.e. one where we cannot copy authentication, etc. from
// the actual host ubuntu-data. Currently this is just a file to disable
// console-conf from running.
func copySafeDefaultData(dst string) error {
consoleConfCompleteFile := filepath.Join(dst, "system-data/var/lib/console-conf/complete")
if err := os.MkdirAll(filepath.Dir(consoleConfCompleteFile), 0755); err != nil {
return err
}
return ioutil.WriteFile(consoleConfCompleteFile, nil, 0644)
}
func copyFromGlobHelper(src, dst, globEx string) error {
matches, err := filepath.Glob(filepath.Join(src, globEx))
if err != nil {
return err
}
for _, p := range matches {
comps := strings.Split(strings.TrimPrefix(p, src), "/")
for i := range comps {
part := filepath.Join(comps[0 : i+1]...)
fi, err := os.Stat(filepath.Join(src, part))
if err != nil {
return err
}
if fi.IsDir() {
if err := os.Mkdir(filepath.Join(dst, part), fi.Mode()); err != nil && !os.IsExist(err) {
return err
}
st, ok := fi.Sys().(*syscall.Stat_t)
if !ok {
return fmt.Errorf("cannot get stat data: %v", err)
}
if err := os.Chown(filepath.Join(dst, part), int(st.Uid), int(st.Gid)); err != nil {
return err
}
} else {
if err := osutil.CopyFile(p, filepath.Join(dst, part), osutil.CopyFlagPreserveAll); err != nil {
return err
}
}
}
}
return nil
}
// states for partition state
const (
// states for LocateState
partitionFound = "found"
partitionNotFound = "not-found"
partitionErrFinding = "error-finding"
// states for MountState
partitionMounted = "mounted"
partitionErrMounting = "error-mounting"
partitionAbsentOptional = "absent-but-optional"
partitionMountedUntrusted = "mounted-untrusted"
// states for UnlockState
partitionUnlocked = "unlocked"
partitionErrUnlocking = "error-unlocking"
// keys used to unlock for UnlockKey
keyRun = "run"
keyFallback = "fallback"
keyRecovery = "recovery"
)
// partitionState is the state of a partition after recover mode has completed
// for degraded mode.
type partitionState struct {
// MountState is whether the partition was mounted successfully or not.
MountState string `json:"mount-state,omitempty"`
// MountLocation is where the partition was mounted.
MountLocation string `json:"mount-location,omitempty"`
// Device is what device the partition corresponds to. It can be the
// physical block device if the partition is unencrypted or if it was not
// successfully unlocked, or it can be a decrypted mapper device if the
// partition was encrypted and successfully decrypted, or it can be the
// empty string (or missing) if the partition was not found at all.
Device string `json:"device,omitempty"`
// FindState indicates whether the partition was found on the disk or not.
FindState string `json:"find-state,omitempty"`
// UnlockState was whether the partition was unlocked successfully or not.
UnlockState string `json:"unlock-state,omitempty"`
// UnlockKey was what key the partition was unlocked with, either "run",
// "fallback" or "recovery".
UnlockKey string `json:"unlock-key,omitempty"`
// unexported internal fields for tracking the device, these are used during
// state machine execution, and then combined into Device during finalize()
// for simple representation to the consumer of degraded.json
// fsDevice is what decrypted mapper device corresponds to the
// partition, it can have the following states
// - successfully decrypted => the decrypted mapper device
// - unencrypted => the block device of the partition
// - identified as decrypted, but failed to decrypt => empty string
fsDevice string
// partDevice is always the physical block device of the partition, in the
// encrypted case this is the physical encrypted partition.
partDevice string
}
type recoverDegradedState struct {
// UbuntuData is the state of the ubuntu-data (or ubuntu-data-enc)
// partition.
UbuntuData partitionState `json:"ubuntu-data,omitempty"`
// UbuntuBoot is the state of the ubuntu-boot partition.
UbuntuBoot partitionState `json:"ubuntu-boot,omitempty"`
// UbuntuSave is the state of the ubuntu-save (or ubuntu-save-enc)
// partition.
UbuntuSave partitionState `json:"ubuntu-save,omitempty"`
// ErrorLog is the log of error messages encountered during recover mode
// setting up degraded mode.
ErrorLog []string `json:"error-log"`
}
func (r *recoverDegradedState) partition(part string) *partitionState {
switch part {
case "ubuntu-data":
return &r.UbuntuData
case "ubuntu-boot":
return &r.UbuntuBoot
case "ubuntu-save":
return &r.UbuntuSave
}
panic(fmt.Sprintf("unknown partition %s", part))
}
func (r *recoverDegradedState) LogErrorf(format string, v ...interface{}) {
msg := fmt.Sprintf(format, v...)
r.ErrorLog = append(r.ErrorLog, msg)
logger.Noticef(msg)
}
// stateFunc is a function which executes a state action, returns the next
// function (for the next) state or nil if it is the final state.
type stateFunc func() (stateFunc, error)
// recoverModeStateMachine is a state machine implementing the logic for
// degraded recover mode.
// A full state diagram for the state machine can be found in
// /cmd/snap-bootstrap/degraded-recover-mode.svg in this repo.
type recoverModeStateMachine struct {
// the current state is the one that is about to be executed
current stateFunc
// device model
model *asserts.Model
// the disk we have all our partitions on
disk disks.Disk
// TODO:UC20: for clarity turn this into into tristate:
// unknown|encrypted|unencrypted
isEncryptedDev bool
// state for tracking what happens as we progress through degraded mode of
// recovery
degradedState *recoverDegradedState
}
// degraded returns whether a degraded recover mode state has fallen back from
// the typical operation to some sort of degraded mode.
func (m *recoverModeStateMachine) degraded() bool {
r := m.degradedState
if m.isEncryptedDev {
// for encrypted devices, we need to have ubuntu-save mounted
if r.UbuntuSave.MountState != partitionMounted {
return true
}
// we also should have all the unlock keys as run keys
if r.UbuntuData.UnlockKey != keyRun {
return true
}
if r.UbuntuSave.UnlockKey != keyRun {
return true
}
} else {
// for unencrypted devices, ubuntu-save must either be mounted or
// absent-but-optional
if r.UbuntuSave.MountState != partitionMounted {
if r.UbuntuSave.MountState != partitionAbsentOptional {
return true
}
}
}
// ubuntu-boot and ubuntu-data should both be mounted
if r.UbuntuBoot.MountState != partitionMounted {
return true
}
if r.UbuntuData.MountState != partitionMounted {
return true
}
// TODO: should we also check MountLocation too?
// we should have nothing in the error log
if len(r.ErrorLog) != 0 {
return true
}
return false
}
func (m *recoverModeStateMachine) diskOpts() *disks.Options {
if m.isEncryptedDev {
return &disks.Options{
IsDecryptedDevice: true,
}
}
return nil
}
func (m *recoverModeStateMachine) verifyMountPoint(dir, name string) error {
matches, err := m.disk.MountPointIsFromDisk(dir, m.diskOpts())
if err != nil {
return err
}
if !matches {
return fmt.Errorf("cannot validate mount: %s mountpoint target %s is expected to be from disk %s but is not", name, dir, m.disk.Dev())
}
return nil
}
func (m *recoverModeStateMachine) setFindState(partName, partUUID string, err error) error {
part := m.degradedState.partition(partName)
if err != nil {
if _, ok := err.(disks.PartitionNotFoundError); ok {
// explicit error that the device was not found
part.FindState = partitionNotFound
m.degradedState.LogErrorf("cannot find %v partition on disk %s", partName, m.disk.Dev())
return nil
}
// the error is not "not-found", so we have a real error
part.FindState = partitionErrFinding
m.degradedState.LogErrorf("error finding %v partition on disk %s: %v", partName, m.disk.Dev(), err)
return nil
}
// device was found
part.FindState = partitionFound
dev := fmt.Sprintf("/dev/disk/by-partuuid/%s", partUUID)
part.partDevice = dev
part.fsDevice = dev
return nil
}
func (m *recoverModeStateMachine) setMountState(part, where string, err error) error {
if err != nil {
m.degradedState.LogErrorf("cannot mount %v: %v", part, err)
m.degradedState.partition(part).MountState = partitionErrMounting
return nil
}
m.degradedState.partition(part).MountState = partitionMounted
m.degradedState.partition(part).MountLocation = where
if err := m.verifyMountPoint(where, part); err != nil {
m.degradedState.LogErrorf("cannot verify %s mount point at %v: %v", part, where, err)
return err
}
return nil
}
func (m *recoverModeStateMachine) setUnlockStateWithRunKey(partName string, unlockRes secboot.UnlockResult, err error) error {
part := m.degradedState.partition(partName)
// save the device if we found it from secboot
if unlockRes.PartDevice != "" {
part.FindState = partitionFound
part.partDevice = unlockRes.PartDevice
part.fsDevice = unlockRes.FsDevice
} else {
part.FindState = partitionNotFound
}
if unlockRes.IsEncrypted {
m.isEncryptedDev = true
}
if err != nil {
// create different error message for encrypted vs unencrypted
if unlockRes.IsEncrypted {
// if we know the device is decrypted we must also always know at
// least the partDevice (which is the encrypted block device)
m.degradedState.LogErrorf("cannot unlock encrypted %s (device %s) with sealed run key: %v", partName, part.partDevice, err)
part.UnlockState = partitionErrUnlocking
} else {
// TODO: we don't know if this is a plain not found or a different error
m.degradedState.LogErrorf("cannot locate %s partition for mounting host data: %v", partName, err)
}
return nil
}
if unlockRes.IsEncrypted {
// unlocked successfully
part.UnlockState = partitionUnlocked
part.UnlockKey = keyRun
}
return nil
}
func (m *recoverModeStateMachine) setUnlockStateWithFallbackKey(partName string, unlockRes secboot.UnlockResult, err error, partitionOptional bool) error {
// first check the result and error for consistency; since we are using udev
// there could be inconsistent results at different points in time
// TODO: consider refactoring UnlockVolumeUsingSealedKeyIfEncrypted to not
// also find the partition on the disk, that should eliminate this
// consistency checking as we can code it such that we don't get these
// possible inconsistencies
// do basic consistency checking on unlockRes to make sure the
// result makes sense.
if unlockRes.FsDevice != "" && err != nil {
// This case should be impossible to enter, we can't
// have a filesystem device but an error set
return fmt.Errorf("internal error: inconsistent return values from UnlockVolumeUsingSealedKeyIfEncrypted for partition %s: %v", partName, err)
}
part := m.degradedState.partition(partName)
// Also make sure that if we previously saw a partition device that we see
// the same device again.
if unlockRes.PartDevice != "" && part.partDevice != "" && unlockRes.PartDevice != part.partDevice {
return fmt.Errorf("inconsistent partitions found for %s: previously found %s but now found %s", partName, part.partDevice, unlockRes.PartDevice)
}
// ensure consistency between encrypted state of the device/disk and what we
// may have seen previously
if m.isEncryptedDev && !unlockRes.IsEncrypted {
// then we previously were able to positively identify an
// ubuntu-data-enc but can't anymore, so we have inconsistent results
// from inspecting the disk which is suspicious and we should fail
return fmt.Errorf("inconsistent disk encryption status: previous access resulted in encrypted, but now is unencrypted from partition %s", partName)
}
// now actually process the result into the state
if unlockRes.PartDevice != "" {
part.FindState = partitionFound
// Note that in some case this may be redundantly assigning the same
// value to partDevice again.
part.partDevice = unlockRes.PartDevice
part.fsDevice = unlockRes.FsDevice
}
// There are a few cases where this could be the first time that we found a
// decrypted device in the UnlockResult, but m.isEncryptedDev is still
// false.
// - The first case is if we couldn't find ubuntu-boot at all, in which case
// we can't use the run object keys from there and instead need to directly
// fallback to trying the fallback object keys from ubuntu-seed
// - The second case is if we couldn't identify an ubuntu-data-enc or an
// ubuntu-data partition at all, we still could have an ubuntu-save-enc
// partition in which case we maybe could still have an encrypted disk that
// needs unlocking with the fallback object keys from ubuntu-seed
//
// As such, if m.isEncryptedDev is false, but unlockRes.IsEncrypted is
// true, then it is safe to assign m.isEncryptedDev to true.
if !m.isEncryptedDev && unlockRes.IsEncrypted {
m.isEncryptedDev = true
}
if err != nil {
// create different error message for encrypted vs unencrypted
if m.isEncryptedDev {
m.degradedState.LogErrorf("cannot unlock encrypted %s partition with sealed fallback key: %v", partName, err)
part.UnlockState = partitionErrUnlocking
} else {
// if we don't have an encrypted device and err != nil, then the
// device must be not-found, see above checks
// if the partition is optional (like ubuntu-save is) then don't
// report an error for ubuntu-save not being found and also set it
// as absent-but-optional
if unlockRes.PartDevice == "" && partitionOptional {
part.MountState = partitionAbsentOptional
} else {
// log the error the partition is mandatory
m.degradedState.LogErrorf("cannot locate %s partition: %v", partName, err)
}
}
return nil
}
if m.isEncryptedDev {
// unlocked successfully
part.UnlockState = partitionUnlocked
// figure out which key/method we used to unlock the partition
switch unlockRes.UnlockMethod {
case secboot.UnlockedWithSealedKey:
part.UnlockKey = keyFallback
case secboot.UnlockedWithRecoveryKey:
part.UnlockKey = keyRecovery
// TODO: should we fail with internal error for default case here?
}
}
return nil
}
func newRecoverModeStateMachine(model *asserts.Model, disk disks.Disk) *recoverModeStateMachine {
m := &recoverModeStateMachine{
model: model,
disk: disk,
degradedState: &recoverDegradedState{
ErrorLog: []string{},
},
}
// first step is to mount ubuntu-boot to check for run mode keys to unlock
// ubuntu-data
m.current = m.mountBoot
return m
}
func (m *recoverModeStateMachine) execute() (finished bool, err error) {
next, err := m.current()
m.current = next
finished = next == nil
if finished && err == nil {
if err := m.finalize(); err != nil {
return true, err
}
}
return finished, err
}
func (m *recoverModeStateMachine) finalize() error {
// check soundness
// the grade check makes sure that if data was mounted unencrypted
// but the model is secured it will end up marked as untrusted
isEncrypted := m.isEncryptedDev || m.model.StorageSafety() == asserts.StorageSafetyEncrypted
part := m.degradedState.partition("ubuntu-data")
if part.MountState == partitionMounted && isEncrypted {
// check that save and data match
// We want to avoid a chosen ubuntu-data
// (e.g. activated with a recovery key) to get access
// via its logins to the secrets in ubuntu-save (in
// particular the policy update auth key)
// TODO:UC20: we should try to be a bit more specific here in checking that
// data and save match, and not mark data as untrusted if we
// know that the real save is locked/protected (or doesn't exist
// in the case of bad corruption) because currently this code will
// mark data as untrusted, even if it was unlocked with the run
// object key and we failed to unlock ubuntu-save at all, which is
// undesirable. This effectively means that you need to have both
// ubuntu-data and ubuntu-save unlockable and have matching marker
// files in order to use the files from ubuntu-data to log-in,
// etc.
trustData, _ := checkDataAndSavePairing(boot.InitramfsHostWritableDir)
if !trustData {
part.MountState = partitionMountedUntrusted
m.degradedState.LogErrorf("cannot trust ubuntu-data, ubuntu-save and ubuntu-data are not marked as from the same install")
}
}
// finally, combine the states of partDevice and fsDevice into the
// exported Device field for marshalling
// ubuntu-boot is easy - it will always be unencrypted so we just set
// Device to partDevice
m.degradedState.partition("ubuntu-boot").Device = m.degradedState.partition("ubuntu-boot").partDevice
// for ubuntu-data and save, we need to actually look at the states
for _, partName := range []string{"ubuntu-data", "ubuntu-save"} {
part := m.degradedState.partition(partName)
if part.fsDevice == "" {
// then the device is encrypted, but we failed to decrypt it, so
// set Device to the encrypted block device
part.Device = part.partDevice
} else {
// all other cases, fsDevice is set to what we want to
// export, either it is set to the decrypted mapper device in the
// case it was successfully decrypted, or it is set to the encrypted
// block device if we failed to decrypt it, or it was set to the
// unencrypted block device if it was unencrypted
part.Device = part.fsDevice
}
}
return nil
}
func (m *recoverModeStateMachine) trustData() bool {
return m.degradedState.partition("ubuntu-data").MountState == partitionMounted
}
// mountBoot is the first state to execute in the state machine, it can
// transition to the following states:
// - if ubuntu-boot is mounted successfully, execute unlockDataRunKey
// - if ubuntu-boot can't be mounted, execute unlockDataFallbackKey
// - if we mounted the wrong ubuntu-boot (or otherwise can't verify which one we
// mounted), return fatal error
func (m *recoverModeStateMachine) mountBoot() (stateFunc, error) {
part := m.degradedState.partition("ubuntu-boot")
// use the disk we mounted ubuntu-seed from as a reference to find
// ubuntu-seed and mount it
partUUID, findErr := m.disk.FindMatchingPartitionUUIDWithFsLabel("ubuntu-boot")
if err := m.setFindState("ubuntu-boot", partUUID, findErr); err != nil {
return nil, err
}
if part.FindState != partitionFound {
// if we didn't find ubuntu-boot, we can't try to unlock data with the
// run key, and should instead just jump straight to attempting to
// unlock with the fallback key
return m.unlockDataFallbackKey, nil
}
// should we fsck ubuntu-boot? probably yes because on some platforms
// (u-boot for example) ubuntu-boot is vfat and it could have been unmounted
// dirtily, and we need to fsck it to ensure it is mounted safely before
// reading keys from it
fsckSystemdOpts := &systemdMountOptions{
NeedsFsck: true,
}
mountErr := doSystemdMount(part.fsDevice, boot.InitramfsUbuntuBootDir, fsckSystemdOpts)
if err := m.setMountState("ubuntu-boot", boot.InitramfsUbuntuBootDir, mountErr); err != nil {
return nil, err
}
if part.MountState == partitionErrMounting {
// if we didn't mount data, then try to unlock data with the
// fallback key
return m.unlockDataFallbackKey, nil
}
// next step try to unlock data with run object
return m.unlockDataRunKey, nil
}
// stateUnlockDataRunKey will try to unlock ubuntu-data with the normal run-mode
// key, and if it fails, progresses to the next state, which is either:
// - failed to unlock data, but we know it's an encrypted device -> try to unlock with fallback key
// - failed to find data at all -> try to unlock save
// - unlocked data with run key -> mount data
func (m *recoverModeStateMachine) unlockDataRunKey() (stateFunc, error) {
runModeKey := filepath.Join(boot.InitramfsBootEncryptionKeyDir, "ubuntu-data.sealed-key")
unlockOpts := &secboot.UnlockVolumeUsingSealedKeyOptions{
// don't allow using the recovery key to unlock, we only try using the
// recovery key after we first try the fallback object
AllowRecoveryKey: false,
}
unlockRes, unlockErr := secbootUnlockVolumeUsingSealedKeyIfEncrypted(m.disk, "ubuntu-data", runModeKey, unlockOpts)
if err := m.setUnlockStateWithRunKey("ubuntu-data", unlockRes, unlockErr); err != nil {
return nil, err
}
if unlockErr != nil {
// we couldn't unlock ubuntu-data with the primary key, or we didn't
// find it in the unencrypted case
if unlockRes.IsEncrypted {
// we know the device is encrypted, so the next state is to try
// unlocking with the fallback key
return m.unlockDataFallbackKey, nil
}
// if we didn't even find the device to the point where it would have
// been identified as decrypted or unencrypted device, we could have
// just entirely lost ubuntu-data-enc, and we could still have an
// encrypted device, so instead try to unlock ubuntu-save with the
// fallback key, the logic there can also handle an unencrypted ubuntu-save
return m.unlockSaveFallbackKey, nil
}
// otherwise successfully unlocked it (or just found it if it was unencrypted)
// so just mount it
return m.mountData, nil
}
func (m *recoverModeStateMachine) unlockDataFallbackKey() (stateFunc, error) {
// try to unlock data with the fallback key on ubuntu-seed, which must have
// been mounted at this point
unlockOpts := &secboot.UnlockVolumeUsingSealedKeyOptions{
// we want to allow using the recovery key if the fallback key fails as
// using the fallback object is the last chance before we give up trying
// to unlock data
AllowRecoveryKey: true,
}
// TODO: this prompts for a recovery key
// TODO: we should somehow customize the prompt to mention what key we need
// the user to enter, and what we are unlocking (as currently the prompt
// says "recovery key" and the partition UUID for what is being unlocked)
dataFallbackKey := filepath.Join(boot.InitramfsSeedEncryptionKeyDir, "ubuntu-data.recovery.sealed-key")
unlockRes, unlockErr := secbootUnlockVolumeUsingSealedKeyIfEncrypted(m.disk, "ubuntu-data", dataFallbackKey, unlockOpts)
const partitionMandatory = false
if err := m.setUnlockStateWithFallbackKey("ubuntu-data", unlockRes, unlockErr, partitionMandatory); err != nil {
return nil, err
}
if unlockErr != nil {
// skip trying to mount data, since we did not unlock data we cannot
// open save with with the run key, so try the fallback one
return m.unlockSaveFallbackKey, nil
}
// unlocked it, now go mount it
return m.mountData, nil
}
func (m *recoverModeStateMachine) mountData() (stateFunc, error) {
data := m.degradedState.partition("ubuntu-data")
// don't do fsck on the data partition, it could be corrupted
mountErr := doSystemdMount(data.fsDevice, boot.InitramfsHostUbuntuDataDir, nil)
if err := m.setMountState("ubuntu-data", boot.InitramfsHostUbuntuDataDir, mountErr); err != nil {
return nil, err
}
if mountErr == nil && m.isEncryptedDev {
// if we succeeded in mounting data and we are encrypted, the next step
// is to unlock save with the run key from ubuntu-data
return m.unlockSaveRunKey, nil
}
// otherwise we always fall back to unlocking save with the fallback key,
// this could be two cases:
// 1. we are unencrypted in which case the secboot function used in
// unlockSaveRunKey will fail and then proceed to trying the fallback key
// function anyways which uses a secboot function that is suitable for
// unencrypted data
// 2. we are encrypted and we failed to mount data successfully, meaning we
// don't have the bare key from ubuntu-data to use, and need to fall back
// to the sealed key from ubuntu-seed
return m.unlockSaveFallbackKey, nil
}
func (m *recoverModeStateMachine) unlockSaveRunKey() (stateFunc, error) {
// to get to this state, we needed to have mounted ubuntu-data on host, so
// if encrypted, we can try to read the run key from host ubuntu-data
saveKey := filepath.Join(dirs.SnapFDEDirUnder(boot.InitramfsHostWritableDir), "ubuntu-save.key")
key, err := ioutil.ReadFile(saveKey)
if err != nil {
// log the error and skip to trying the fallback key
m.degradedState.LogErrorf("cannot access run ubuntu-save key: %v", err)
return m.unlockSaveFallbackKey, nil
}
unlockRes, unlockErr := secbootUnlockEncryptedVolumeUsingKey(m.disk, "ubuntu-save", key)
if err := m.setUnlockStateWithRunKey("ubuntu-save", unlockRes, unlockErr); err != nil {
return nil, err
}
if unlockErr != nil {
// failed to unlock with run key, try fallback key
return m.unlockSaveFallbackKey, nil
}
// unlocked it properly, go mount it
return m.mountSave, nil
}
func (m *recoverModeStateMachine) unlockSaveFallbackKey() (stateFunc, error) {
// remember what we assumed about encryption before looking at
// save
assumeEncrypted := m.isEncryptedDev
// try to unlock save with the fallback key on ubuntu-seed, which must have
// been mounted at this point
unlockOpts := &secboot.UnlockVolumeUsingSealedKeyOptions{
// we want to allow using the recovery key if the fallback key fails as
// using the fallback object is the last chance before we give up trying
// to unlock save
AllowRecoveryKey: true,
}
saveFallbackKey := filepath.Join(boot.InitramfsSeedEncryptionKeyDir, "ubuntu-save.recovery.sealed-key")
// TODO: this prompts again for a recover key, but really this is the
// reinstall key we will prompt for
// TODO: we should somehow customize the prompt to mention what key we need
// the user to enter, and what we are unlocking (as currently the prompt
// says "recovery key" and the partition UUID for what is being unlocked)
unlockRes, unlockErr := secbootUnlockVolumeUsingSealedKeyIfEncrypted(m.disk, "ubuntu-save", saveFallbackKey, unlockOpts)
const partitionOptionalIfUnencrypted = true
if err := m.setUnlockStateWithFallbackKey("ubuntu-save", unlockRes, unlockErr, partitionOptionalIfUnencrypted); err != nil {
return nil, err
}
if unlockErr != nil {
// all done, nothing left to try and mount, mounting ubuntu-save is the
// last step but we couldn't find or unlock it
return nil, nil
}
// do a consistency check to make sure that if we found ubuntu-data
// unencrypted that we don't also mount ubuntu-save as encrypted
data := m.degradedState.partition("ubuntu-data")
if unlockRes.IsEncrypted && data.FindState == partitionFound && !assumeEncrypted {
return nil, fmt.Errorf("inconsistent encryption status for disk %s: ubuntu-data (device %s) was found unencrypted but ubuntu-save (device %s) was found to be encrypted", m.disk.Dev(), data.fsDevice, unlockRes.FsDevice)
}
// otherwise we unlocked it, so go mount it
return m.mountSave, nil
}
func (m *recoverModeStateMachine) mountSave() (stateFunc, error) {
save := m.degradedState.partition("ubuntu-save")
// TODO: should we fsck ubuntu-save ?
mountErr := doSystemdMount(save.fsDevice, boot.InitramfsUbuntuSaveDir, nil)
if err := m.setMountState("ubuntu-save", boot.InitramfsUbuntuSaveDir, mountErr); err != nil {
return nil, err
}
// all done, nothing left to try and mount
return nil, nil
}
func generateMountsModeRecover(mst *initramfsMountsState) error {
// steps 1 and 2 are shared with install mode
model, snaps, err := generateMountsCommonInstallRecover(mst)
if err != nil {
return err
}
// get the disk that we mounted the ubuntu-seed partition from as a
// reference point for future mounts
disk, err := disks.DiskFromMountPoint(boot.InitramfsUbuntuSeedDir, nil)
if err != nil {
return err
}
// 3. run the state machine logic for mounting partitions, this involves
// trying to unlock then mount ubuntu-data, and then unlocking and
// mounting ubuntu-save
// see the state* functions for details of what each step does and
// possible transition points
machine, err := func() (machine *recoverModeStateMachine, err error) {
// first state to execute is to unlock ubuntu-data with the run key
machine = newRecoverModeStateMachine(model, disk)
for {
finished, err := machine.execute()
// TODO: consider whether certain errors are fatal or not
if err != nil {
return nil, err
}
if finished {
break
}
}
return machine, nil
}()
if err != nil {
return err
}
// 3.1 write out degraded.json if we ended up falling back somewhere
if machine.degraded() {