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key_manager.go
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key_manager.go
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// Copyright 2016 Keybase Inc. All rights reserved.
// Use of this source code is governed by a BSD
// license that can be found in the LICENSE file.
package libkbfs
import (
"github.com/keybase/client/go/kbfs/data"
"github.com/keybase/client/go/kbfs/kbfscrypto"
"github.com/keybase/client/go/kbfs/kbfsmd"
"github.com/keybase/client/go/kbfs/libkey"
"github.com/keybase/client/go/kbfs/tlf"
"github.com/keybase/client/go/kbfs/tlfhandle"
kbname "github.com/keybase/client/go/kbun"
"github.com/keybase/client/go/libkb"
"github.com/keybase/client/go/logger"
"github.com/keybase/client/go/protocol/keybase1"
"github.com/pkg/errors"
"golang.org/x/net/context"
)
// KeyManagerStandard implements the KeyManager interface by fetching
// keys from KeyOps and KBPKI, and computing the complete keys
// necessary to run KBFS.
type KeyManagerStandard struct {
config Config
log logger.Logger
deferLog logger.Logger
}
// NewKeyManagerStandard returns a new KeyManagerStandard
func NewKeyManagerStandard(config Config) *KeyManagerStandard {
log := config.MakeLogger("")
return &KeyManagerStandard{config, log, log.CloneWithAddedDepth(1)}
}
// GetTLFCryptKeyForEncryption implements the KeyManager interface for
// KeyManagerStandard.
func (km *KeyManagerStandard) GetTLFCryptKeyForEncryption(ctx context.Context,
kmd libkey.KeyMetadata) (tlfCryptKey kbfscrypto.TLFCryptKey, err error) {
return km.getTLFCryptKeyUsingCurrentDevice(ctx, kmd,
kmd.LatestKeyGeneration(), false)
}
// GetTLFCryptKeyForMDDecryption implements the KeyManager interface
// for KeyManagerStandard.
func (km *KeyManagerStandard) GetTLFCryptKeyForMDDecryption(
ctx context.Context, kmdToDecrypt, kmdWithKeys libkey.KeyMetadata) (
tlfCryptKey kbfscrypto.TLFCryptKey, err error) {
return km.getTLFCryptKey(ctx, kmdWithKeys, kmdToDecrypt.LatestKeyGeneration(),
getTLFCryptKeyAnyDevice|getTLFCryptKeyDoCache)
}
// GetTLFCryptKeyForBlockDecryption implements the KeyManager interface for
// KeyManagerStandard.
func (km *KeyManagerStandard) GetTLFCryptKeyForBlockDecryption(
ctx context.Context, kmd libkey.KeyMetadata, blockPtr data.BlockPointer) (
tlfCryptKey kbfscrypto.TLFCryptKey, err error) {
return km.getTLFCryptKeyUsingCurrentDevice(ctx, kmd, blockPtr.KeyGen, true)
}
// GetFirstTLFCryptKey implements the KeyManager interface for
// KeyManagerStandard.
func (km *KeyManagerStandard) GetFirstTLFCryptKey(
ctx context.Context, kmd libkey.KeyMetadata) (
kbfscrypto.TLFCryptKey, error) {
return km.getTLFCryptKey(
ctx, kmd, kbfsmd.FirstValidKeyGen, getTLFCryptKeyAnyDevice)
}
// GetTLFCryptKeyOfAllGenerations implements the KeyManager interface for
// KeyManagerStandard.
func (km *KeyManagerStandard) GetTLFCryptKeyOfAllGenerations(
ctx context.Context, kmd libkey.KeyMetadata) (
keys []kbfscrypto.TLFCryptKey, err error) {
for g := kbfsmd.FirstValidKeyGen; g <= kmd.LatestKeyGeneration(); g++ {
var key kbfscrypto.TLFCryptKey
key, err = km.getTLFCryptKeyUsingCurrentDevice(ctx, kmd, g, true)
if err != nil {
return keys, err
}
keys = append(keys, key)
}
return keys, nil
}
func (km *KeyManagerStandard) getTLFCryptKeyUsingCurrentDevice(
ctx context.Context, kmd libkey.KeyMetadata, keyGen kbfsmd.KeyGen, cache bool) (
tlfCryptKey kbfscrypto.TLFCryptKey, err error) {
flags := getTLFCryptKeyFlags(0)
if cache {
flags = getTLFCryptKeyDoCache
}
return km.getTLFCryptKey(ctx, kmd, keyGen, flags)
}
type getTLFCryptKeyFlags byte
const (
getTLFCryptKeyAnyDevice getTLFCryptKeyFlags = 1 << iota
getTLFCryptKeyDoCache
getTLFCryptKeyPromptPaper
)
func (km *KeyManagerStandard) getTLFCryptKey(ctx context.Context,
kmd libkey.KeyMetadata, keyGen kbfsmd.KeyGen, flags getTLFCryptKeyFlags) (
kbfscrypto.TLFCryptKey, error) {
tlfID := kmd.TlfID()
// Classic public TLFs and public implicit teams use a dummy crypt key.
if kmd.TypeForKeying() == tlf.PublicKeying || tlfID.Type() == tlf.Public {
return kbfscrypto.PublicTLFCryptKey, nil
}
if keyGen < kbfsmd.FirstValidKeyGen {
return kbfscrypto.TLFCryptKey{}, errors.WithStack(kbfsmd.InvalidKeyGenerationError{TlfID: tlfID, KeyGen: keyGen})
}
// Is this some key we don't know yet? Shouldn't really ever
// happen, but during migration there was a race that made this
// possible (KBFS-3774). If the key gen really doesn't exist,
// we'll return an InvalidKeyGenerationError below.
if keyGen > kmd.LatestKeyGeneration() {
km.log.CDebugf(ctx, "Key gen %d is bigger than latest key gen %d",
keyGen, kmd.LatestKeyGeneration())
}
// look in the cache first
kcache := km.config.KeyCache()
tlfCryptKey, err := kcache.GetTLFCryptKey(tlfID, keyGen)
switch err := err.(type) {
case nil:
return tlfCryptKey, nil
case KeyCacheMissError:
break
default:
return kbfscrypto.TLFCryptKey{}, err
}
// Team TLF keys come from the service.
if kmd.TypeForKeying() == tlf.TeamKeying {
tid, err := kmd.GetTlfHandle().FirstResolvedWriter().AsTeam()
if err != nil {
return kbfscrypto.TLFCryptKey{}, err
}
keys, _, err := km.config.KBPKI().GetTeamTLFCryptKeys(
ctx, tid, keyGen, km.config.OfflineAvailabilityForID(tlfID))
if err != nil {
return kbfscrypto.TLFCryptKey{}, err
}
tlfCryptKey, ok := keys[keyGen]
if !ok {
return kbfscrypto.TLFCryptKey{},
kbfsmd.InvalidKeyGenerationError{TlfID: tlfID, KeyGen: keyGen}
}
if flags&getTLFCryptKeyDoCache != 0 {
if err = kcache.PutTLFCryptKey(
tlfID, keyGen, tlfCryptKey); err != nil {
return kbfscrypto.TLFCryptKey{}, err
}
}
return tlfCryptKey, nil
}
// Get the encrypted version of this secret key for this device
kbpki := km.config.KBPKI()
session, err := kbpki.GetCurrentSession(ctx)
if err != nil {
return kbfscrypto.TLFCryptKey{}, err
}
clientHalf, serverHalfID, cryptPublicKey, err :=
km.getTLFCryptKeyParams(ctx, kmd, keyGen, session.UID,
session.Name, flags)
var notPerDeviceEncrypted bool
if _, notPerDeviceEncrypted = err.(kbfsmd.TLFCryptKeyNotPerDeviceEncrypted); notPerDeviceEncrypted { // nolint
// get the key we want using the current crypt key
currKeyGen := kmd.LatestKeyGeneration()
// look in the cache first
latestKey, err := kcache.GetTLFCryptKey(tlfID, currKeyGen)
switch err := err.(type) {
case nil:
case KeyCacheMissError:
// not cached, look up the params
clientHalf, serverHalfID, cryptPublicKey, err2 :=
km.getTLFCryptKeyParams(ctx, kmd, currKeyGen,
session.UID, session.Name, flags)
if err2 != nil {
return kbfscrypto.TLFCryptKey{}, err2
}
// unmask it
latestKey, err2 = km.unmaskTLFCryptKey(ctx, serverHalfID, cryptPublicKey, clientHalf)
if err2 != nil {
return kbfscrypto.TLFCryptKey{}, err2
}
default:
return kbfscrypto.TLFCryptKey{}, err
}
// get the historic key we want
tlfCryptKey, err =
kmd.GetHistoricTLFCryptKey(km.config.Codec(), keyGen, latestKey)
if err != nil {
km.log.CDebugf(
ctx, "Can't get historic TLF crypt key for id=%s, keyGen=%d",
tlfID, keyGen)
return kbfscrypto.TLFCryptKey{}, err
}
} else if err != nil {
return kbfscrypto.TLFCryptKey{}, err
} else {
// unmask it
tlfCryptKey, err = km.unmaskTLFCryptKey(ctx, serverHalfID, cryptPublicKey, clientHalf)
if err != nil {
return kbfscrypto.TLFCryptKey{}, err
}
}
if flags&getTLFCryptKeyDoCache != 0 {
if err = kcache.PutTLFCryptKey(tlfID, keyGen, tlfCryptKey); err != nil {
return kbfscrypto.TLFCryptKey{}, err
}
}
return tlfCryptKey, nil
}
func (km *KeyManagerStandard) getTLFCryptKeyParams(
ctx context.Context, kmd libkey.KeyMetadata,
keyGen kbfsmd.KeyGen, uid keybase1.UID, username kbname.NormalizedUsername,
flags getTLFCryptKeyFlags) (
clientHalf kbfscrypto.TLFCryptKeyClientHalf,
serverHalfID kbfscrypto.TLFCryptKeyServerHalfID,
cryptPublicKey kbfscrypto.CryptPublicKey, err error) {
kbpki := km.config.KBPKI()
crypto := km.config.Crypto()
localMakeRekeyReadError := func(err error) error {
return makeRekeyReadError(
ctx, err, kbpki, km.config, kmd, uid, username)
}
if flags&getTLFCryptKeyAnyDevice != 0 {
publicKeys, err := kbpki.GetCryptPublicKeys(
ctx, uid, km.config.OfflineAvailabilityForID(kmd.TlfID()))
if err != nil {
return kbfscrypto.TLFCryptKeyClientHalf{},
kbfscrypto.TLFCryptKeyServerHalfID{},
kbfscrypto.CryptPublicKey{}, err
}
keys := make([]EncryptedTLFCryptKeyClientAndEphemeral, 0,
len(publicKeys))
serverHalfIDs := make([]kbfscrypto.TLFCryptKeyServerHalfID, 0, len(publicKeys))
publicKeyLookup := make([]int, 0, len(publicKeys))
for i, k := range publicKeys {
ePublicKey, encryptedClientHalf, serverHalfID, found, err := kmd.GetTLFCryptKeyParams(keyGen, uid, k)
if _, notPerDeviceEncrypted := err.(kbfsmd.TLFCryptKeyNotPerDeviceEncrypted); notPerDeviceEncrypted {
return kbfscrypto.TLFCryptKeyClientHalf{},
kbfscrypto.TLFCryptKeyServerHalfID{},
kbfscrypto.CryptPublicKey{}, err
}
if err != nil {
km.log.CDebugf(ctx, "Got error for GetTLFCryptKeyParams(%d, %v, %v); skipping: %+v", keyGen, uid, k, err)
continue
}
if !found {
km.log.CDebugf(ctx, "Could not find key info for(%d, %v, %v); skipping", keyGen, uid, k)
continue
}
serverHalfIDs = append(serverHalfIDs, serverHalfID)
keys = append(keys, EncryptedTLFCryptKeyClientAndEphemeral{
PubKey: k,
ClientHalf: encryptedClientHalf,
EPubKey: ePublicKey,
})
publicKeyLookup = append(publicKeyLookup, i)
}
if len(keys) == 0 {
err := errors.New("no valid public keys found")
return kbfscrypto.TLFCryptKeyClientHalf{},
kbfscrypto.TLFCryptKeyServerHalfID{},
kbfscrypto.CryptPublicKey{},
localMakeRekeyReadError(err)
}
var index int
clientHalf, index, err = crypto.DecryptTLFCryptKeyClientHalfAny(ctx,
keys, flags&getTLFCryptKeyPromptPaper != 0)
cause := errors.Cause(err)
_, isDecryptError := cause.(libkb.DecryptionError)
_, isNoKeyError := cause.(libkb.NoSecretKeyError)
if isDecryptError || isNoKeyError {
km.log.CDebugf(ctx, "Got decryption error from service: %+v", err)
return kbfscrypto.TLFCryptKeyClientHalf{},
kbfscrypto.TLFCryptKeyServerHalfID{},
kbfscrypto.CryptPublicKey{},
localMakeRekeyReadError(err)
} else if err != nil {
return kbfscrypto.TLFCryptKeyClientHalf{},
kbfscrypto.TLFCryptKeyServerHalfID{},
kbfscrypto.CryptPublicKey{}, err
}
serverHalfID = serverHalfIDs[index]
cryptPublicKey = publicKeys[publicKeyLookup[index]]
} else {
session, err := kbpki.GetCurrentSession(ctx)
if err != nil {
return kbfscrypto.TLFCryptKeyClientHalf{},
kbfscrypto.TLFCryptKeyServerHalfID{},
kbfscrypto.CryptPublicKey{}, err
}
cryptPublicKey = session.CryptPublicKey
ePublicKey, encryptedClientHalf, foundServerHalfID, found, err :=
kmd.GetTLFCryptKeyParams(keyGen, uid, cryptPublicKey)
if _, notPerDeviceEncrypted := err.(kbfsmd.TLFCryptKeyNotPerDeviceEncrypted); notPerDeviceEncrypted {
return kbfscrypto.TLFCryptKeyClientHalf{},
kbfscrypto.TLFCryptKeyServerHalfID{},
kbfscrypto.CryptPublicKey{}, err
}
if err != nil {
return kbfscrypto.TLFCryptKeyClientHalf{},
kbfscrypto.TLFCryptKeyServerHalfID{},
kbfscrypto.CryptPublicKey{}, err
} else if !found {
return kbfscrypto.TLFCryptKeyClientHalf{},
kbfscrypto.TLFCryptKeyServerHalfID{},
kbfscrypto.CryptPublicKey{},
localMakeRekeyReadError(errors.Errorf(
"could not find params for "+
"uid=%s device key=%s",
uid, cryptPublicKey))
}
clientHalf, err = crypto.DecryptTLFCryptKeyClientHalf(
ctx, ePublicKey, encryptedClientHalf)
if err != nil {
return kbfscrypto.TLFCryptKeyClientHalf{},
kbfscrypto.TLFCryptKeyServerHalfID{},
kbfscrypto.CryptPublicKey{}, err
}
serverHalfID = foundServerHalfID
}
return
}
func (km *KeyManagerStandard) unmaskTLFCryptKey(ctx context.Context, serverHalfID kbfscrypto.TLFCryptKeyServerHalfID,
cryptPublicKey kbfscrypto.CryptPublicKey,
clientHalf kbfscrypto.TLFCryptKeyClientHalf) (
kbfscrypto.TLFCryptKey, error) {
// get the server-side key-half, do the unmasking, possibly cache the result, return
// TODO: can parallelize the get() with decryption
serverHalf, err := km.config.KeyOps().GetTLFCryptKeyServerHalf(ctx, serverHalfID,
cryptPublicKey)
if err != nil {
return kbfscrypto.TLFCryptKey{}, err
}
tlfCryptKey := kbfscrypto.UnmaskTLFCryptKey(serverHalf, clientHalf)
return tlfCryptKey, nil
}
func (km *KeyManagerStandard) updateKeyBundles(ctx context.Context,
md *RootMetadata,
updatedWriterKeys, updatedReaderKeys kbfsmd.UserDevicePublicKeys,
ePubKey kbfscrypto.TLFEphemeralPublicKey,
ePrivKey kbfscrypto.TLFEphemeralPrivateKey,
tlfCryptKeys []kbfscrypto.TLFCryptKey) error {
serverHalves, err := md.updateKeyBundles(
km.config.Codec(), updatedWriterKeys, updatedReaderKeys,
ePubKey, ePrivKey, tlfCryptKeys)
if err != nil {
return err
}
// Push new keys to the key server.
//
// TODO: Should accumulate the server halves across multiple
// key generations and push them all at once right before the
// MD push, although this only really matters for MDv2.
for _, serverHalvesGen := range serverHalves {
if err = km.config.KeyOps().
PutTLFCryptKeyServerHalves(ctx, serverHalvesGen); err != nil {
return err
}
}
return nil
}
func (km *KeyManagerStandard) usersWithNewDevices(ctx context.Context,
tlfID tlf.ID, keys, expectedKeys kbfsmd.UserDevicePublicKeys) map[keybase1.UID]bool {
users := make(map[keybase1.UID]bool)
for u, expectedDeviceKeys := range expectedKeys {
deviceKeys, ok := keys[u]
if !ok {
// Currently there probably shouldn't be any new users
// in the handle, but don't error just in case we ever
// want to support that in the future.
km.log.CInfof(ctx, "Rekey %s: adding new user %s", tlfID, u)
users[u] = true
continue
}
for key := range expectedDeviceKeys {
km.log.CDebugf(ctx, "Checking key %v", key)
if !deviceKeys[key] {
km.log.CInfof(ctx, "Rekey %s: adding new device %s for user %s",
tlfID, key, u)
users[u] = true
break
}
}
}
return users
}
func (km *KeyManagerStandard) usersWithRemovedDevices(ctx context.Context,
tlfID tlf.ID, keys, expectedKeys kbfsmd.UserDevicePublicKeys) map[keybase1.UID]bool {
users := make(map[keybase1.UID]bool)
for u, deviceKeys := range keys {
expectedDeviceKeys, ok := expectedKeys[u]
if !ok {
// Currently there probably shouldn't be any users removed
// from the handle, but don't error just in case we ever
// want to support that in the future.
km.log.CInfof(ctx, "Rekey %s: removing user %s", tlfID, u)
users[u] = true
continue
}
for key := range deviceKeys {
// Make sure every kid has an expected key
if !expectedDeviceKeys[key] {
km.log.CInfof(ctx, "Rekey %s: removing device %s for user %s",
tlfID, key, u)
users[u] = true
break
}
}
}
return users
}
func (km *KeyManagerStandard) identifyUIDSets(ctx context.Context,
tlfID tlf.ID, writersToIdentify map[keybase1.UID]bool,
readersToIdentify map[keybase1.UID]bool) error {
ids := make([]keybase1.UserOrTeamID, 0,
len(writersToIdentify)+len(readersToIdentify))
for u := range writersToIdentify {
ids = append(ids, u.AsUserOrTeam())
}
for u := range readersToIdentify {
ids = append(ids, u.AsUserOrTeam())
}
kbpki := km.config.KBPKI()
// Let the service know that we're doing the identifies because of
// a rekey, so they can suppress popups in some cases.
ctx, err := tlfhandle.MakeExtendedIdentify(
ctx, keybase1.TLFIdentifyBehavior_KBFS_REKEY)
if err != nil {
return err
}
return tlfhandle.IdentifyUserList(
ctx, kbpki, kbpki, ids, tlfID.Type(),
km.config.OfflineAvailabilityForID(tlfID))
}
// generateKeyMapForUsers returns a kbfsmd.UserDevicePublicKeys object for
// the given list of users. Note that keyless users are retained in
// the returned kbfsmd.UserDevicePublicKeys object.
func (km *KeyManagerStandard) generateKeyMapForUsers(
ctx context.Context, users []keybase1.UserOrTeamID,
offline keybase1.OfflineAvailability) (
kbfsmd.UserDevicePublicKeys, error) {
keyMap := make(kbfsmd.UserDevicePublicKeys)
// TODO: parallelize
for _, w := range users {
uid := w.AsUserOrBust() // only private TLFs should call this
// HACK: clear cache
km.config.KeybaseService().FlushUserFromLocalCache(ctx, uid)
publicKeys, err := km.config.KBPKI().GetCryptPublicKeys(
ctx, uid, offline)
if err != nil {
return nil, err
}
keyMap[uid] = make(kbfsmd.DevicePublicKeys)
for _, key := range publicKeys {
keyMap[uid][key] = true
}
}
return keyMap, nil
}
// Rekey implements the KeyManager interface for KeyManagerStandard.
//
// TODO: Make this less terrible. See KBFS-1799.
func (km *KeyManagerStandard) Rekey(ctx context.Context, md *RootMetadata, promptPaper bool) (
mdChanged bool, cryptKey *kbfscrypto.TLFCryptKey, err error) {
km.log.CDebugf(ctx, "Rekey %s (prompt for paper key: %t)",
md.TlfID(), promptPaper)
defer func() { km.deferLog.CDebugf(ctx, "Rekey %s done: %+v", md.TlfID(), err) }()
if md.TypeForKeying() == tlf.TeamKeying {
return false, nil, errors.New(
"Rekeying is not done by KBFS for team TLFs")
}
currKeyGen := md.LatestKeyGeneration()
if (md.TypeForKeying() == tlf.PublicKeying) != (currKeyGen == kbfsmd.PublicKeyGen) {
return false, nil, errors.Errorf(
"ID %v has keying type=%s but currKeyGen is %d (isPublic=%t)",
md.TlfID(), md.TypeForKeying(), currKeyGen,
currKeyGen == kbfsmd.PublicKeyGen)
}
if promptPaper && md.TypeForKeying() != tlf.PrivateKeying {
return false, nil, errors.Errorf(
"promptPaper set for non-private TLF %v", md.TlfID())
}
handle := md.GetTlfHandle()
session, err := km.config.KBPKI().GetCurrentSession(ctx)
if err != nil {
return false, nil, err
}
idGetter := tlfhandle.ConstIDGetter{ID: md.TlfID()}
resolvedHandle, err := handle.ResolveAgain(
ctx, km.config.KBPKI(), idGetter, km.config)
if err != nil {
return false, nil, err
}
isWriter := resolvedHandle.IsWriter(session.UID)
if md.TypeForKeying() == tlf.PrivateKeying && !isWriter {
// If I was already a reader, there's nothing more to do
if handle.IsReader(session.UID) {
resolvedHandle = handle
km.log.CDebugf(ctx, "Local user is not a writer, and was "+
"already a reader; reverting back to the original handle")
} else {
// Only allow yourself to change
resolvedHandle, err = handle.ResolveAgainForUser(
ctx, km.config.KBPKI(), idGetter, km.config, session.UID)
if err != nil {
return false, nil, err
}
}
}
eq, err := handle.Equals(km.config.Codec(), *resolvedHandle)
if err != nil {
return false, nil, err
}
handleChanged := !eq
if handleChanged {
km.log.CDebugf(ctx, "handle for %s resolved to %s",
handle.GetCanonicalPath(),
resolvedHandle.GetCanonicalPath())
// Check with the server to see if the handle became a conflict.
latestHandle, err := km.config.MDOps().GetLatestHandleForTLF(ctx, md.TlfID())
if err != nil {
return false, nil, err
}
if latestHandle.ConflictInfo != nil {
km.log.CDebugf(ctx, "handle for %s is conflicted",
handle.GetCanonicalPath())
}
resolvedHandle, err = resolvedHandle.WithUpdatedConflictInfo(
km.config.Codec(), latestHandle.ConflictInfo)
if err != nil {
return false, nil, err
}
}
// For a public or team TLF there's no rekeying to be done, but we
// should still update the writer list.
if md.TypeForKeying() != tlf.PrivateKeying {
if !handleChanged {
km.log.CDebugf(ctx,
"Skipping rekeying %s (%s): handle hasn't changed",
md.TlfID(), md.TypeForKeying())
return false, nil, nil
}
return true, nil, md.updateFromTlfHandle(resolvedHandle)
}
// Decide whether we have a new device and/or a revoked device, or neither.
// Look up all the device public keys for all writers and readers first.
incKeyGen := currKeyGen < kbfsmd.FirstValidKeyGen
if !isWriter && incKeyGen {
// Readers cannot create the first key generation
return false, nil, tlfhandle.NewReadAccessError(
resolvedHandle, session.Name, resolvedHandle.GetCanonicalPath())
}
offline := km.config.OfflineAvailabilityForID(md.TlfID())
// All writer keys in the desired keyset
updatedWriterKeys, err := km.generateKeyMapForUsers(
ctx, resolvedHandle.ResolvedWriters(), offline)
if err != nil {
return false, nil, err
}
// All reader keys in the desired keyset
updatedReaderKeys, err := km.generateKeyMapForUsers(
ctx, resolvedHandle.ResolvedReaders(), offline)
if err != nil {
return false, nil, err
}
addNewReaderDevice := false
addNewWriterDevice := false
var newReaderUsers map[keybase1.UID]bool
var newWriterUsers map[keybase1.UID]bool
var readersToPromote map[keybase1.UID]bool
// Figure out if we need to add or remove any keys.
// If we're already incrementing the key generation then we don't need to
// figure out the key delta.
addNewReaderDeviceForSelf := false
if !incKeyGen {
// See if there is at least one new device in relation to the
// current key bundle
writers, readers, err := md.getUserDevicePublicKeys()
if err != nil {
return false, nil, err
}
newWriterUsers = km.usersWithNewDevices(
ctx, md.TlfID(), writers, updatedWriterKeys)
newReaderUsers = km.usersWithNewDevices(
ctx, md.TlfID(), readers, updatedReaderKeys)
addNewWriterDevice = len(newWriterUsers) > 0
addNewReaderDevice = len(newReaderUsers) > 0
wRemoved := km.usersWithRemovedDevices(
ctx, md.TlfID(), writers, updatedWriterKeys)
rRemoved := km.usersWithRemovedDevices(
ctx, md.TlfID(), readers, updatedReaderKeys)
readersToPromote = make(map[keybase1.UID]bool, len(rRemoved))
// Before we add the removed devices, check if we are adding a
// new reader device for ourselves.
_, addNewReaderDeviceForSelf = newReaderUsers[session.UID]
for u := range rRemoved {
// FIXME (potential): this could cause a reader to attempt to rekey
// in the case of a revocation for the currently logged-in user. I
// _think_ incKeyGen above protects against this, but I'm not
// confident.
newReaderUsers[u] = true
// Track which readers have been promoted. This must happen before
// the following line adds all the removed writers to the writer
// set
if newWriterUsers[u] {
readersToPromote[u] = true
}
}
for u := range wRemoved {
newWriterUsers[u] = true
}
incKeyGen = len(wRemoved) > 0 || (len(rRemoved) > len(readersToPromote))
if err := km.identifyUIDSets(ctx, md.TlfID(), newWriterUsers, newReaderUsers); err != nil {
return false, nil, err
}
}
if !addNewReaderDevice && !addNewWriterDevice && !incKeyGen &&
!handleChanged {
km.log.CDebugf(ctx,
"Skipping rekeying %s (private): no new or removed devices, no new keygen, and handle hasn't changed",
md.TlfID())
return false, nil, nil
}
if !isWriter {
// This shouldn't happen; see the code above where we
// either use the original handle or resolve only the
// current UID.
if len(readersToPromote) != 0 {
return false, nil, errors.New(
"promoted readers unexpectedly non-empty")
}
if _, userHasNewKeys := newReaderUsers[session.UID]; userHasNewKeys {
// Only rekey the logged-in reader.
updatedWriterKeys = nil
updatedReaderKeys = kbfsmd.UserDevicePublicKeys{
session.UID: updatedReaderKeys[session.UID],
}
delete(newReaderUsers, session.UID)
} else {
// No new reader device for our user, so the reader can't do
// anything
return false, nil, RekeyIncompleteError{}
}
}
// If promotedReader is non-empty, then isWriter is true (see
// check above).
err = md.promoteReaders(readersToPromote)
if err != nil {
return false, nil, err
}
// Generate ephemeral keys to be used by addNewDevice,
// incKeygen, or both. ePrivKey will be discarded at the end
// of the function.
ePubKey, ePrivKey, err :=
km.config.Crypto().MakeRandomTLFEphemeralKeys()
// Note: For MDv3, if incKeyGen is true, then all the
// manipulations below aren't needed, since they'll just be
// replaced by the new key generation. However, do them
// anyway, as they may have some side effects, e.g. removing
// server key halves.
// If there's at least one new device, add that device to every key bundle.
if addNewReaderDevice || addNewWriterDevice {
start, end := md.KeyGenerationsToUpdate()
if start >= end {
return false, nil, errors.New(
"Unexpected empty range for key generations to update")
}
cryptKeys := make([]kbfscrypto.TLFCryptKey, end-start)
flags := getTLFCryptKeyAnyDevice
if promptPaper {
flags |= getTLFCryptKeyPromptPaper
}
for keyGen := start; keyGen < end; keyGen++ {
currTlfCryptKey, err := km.getTLFCryptKey(
ctx, md.ReadOnly(), keyGen, flags)
if err != nil {
return false, nil, err
}
cryptKeys[keyGen-start] = currTlfCryptKey
}
err = km.updateKeyBundles(ctx, md, updatedWriterKeys,
updatedReaderKeys, ePubKey, ePrivKey, cryptKeys)
if err != nil {
return false, nil, err
}
}
// Make sure the private MD is decrypted if it wasn't already. We
// have to do this here, before adding a new key generation, since
// decryptMDPrivateData assumes that the MD is always encrypted
// using the latest key gen.
if !md.IsReadable() && len(md.GetSerializedPrivateMetadata()) > 0 {
pmd, err := decryptMDPrivateData(
ctx, km.config.Codec(), km.config.Crypto(),
km.config.BlockCache(), km.config.BlockOps(), km, km.config.KBPKI(),
km.config, km.config.Mode(), session.UID,
md.GetSerializedPrivateMetadata(), md, md, km.log)
if err != nil {
return false, nil, err
}
md.data = pmd
}
defer func() {
// On our way back out, update the md with the
// resolved handle if at least part of a rekey was
// performed. Also, if we return true for mdChanged
// with a nil error or RekeyIncompleteError{}, we must
// call md.finalizeRekey() first.
_, isRekeyIncomplete := err.(RekeyIncompleteError)
if err == nil || isRekeyIncomplete {
updateErr := md.updateFromTlfHandle(resolvedHandle)
if updateErr != nil {
mdChanged = false
cryptKey = nil
err = updateErr
}
if mdChanged {
finalizeErr := md.finalizeRekey(
km.config.Codec())
if finalizeErr != nil {
mdChanged = false
cryptKey = nil
err = finalizeErr
}
}
}
}()
if !isWriter {
if len(newReaderUsers) > 0 || addNewWriterDevice || incKeyGen {
// If we're a reader but we haven't completed all the work, return
// RekeyIncompleteError.
return addNewReaderDeviceForSelf, nil, RekeyIncompleteError{}
}
// Otherwise, there's nothing left to do!
return true, nil, nil
} else if !incKeyGen {
// we're done!
return true, nil, nil
}
// Send rekey start notification once we're sure that this device
// can perform the rekey. Don't send this for the first key
// generation though, since that's not really a "re"key.
//
// TODO: Shouldn't this happen earlier?
if currKeyGen >= kbfsmd.FirstValidKeyGen {
km.config.Reporter().Notify(ctx, rekeyNotification(
ctx, km.config, resolvedHandle, false))
}
// Delete server-side key halves for any revoked devices, if
// there are any previous key generations. Do this before
// adding a new key generation, as MDv3 only keeps track of
// the latest key generation.
//
// TODO: Add test coverage for this.
if currKeyGen >= kbfsmd.FirstValidKeyGen {
allRemovalInfo, err := md.revokeRemovedDevices(
updatedWriterKeys, updatedReaderKeys)
if err != nil {
return false, nil, err
}
if len(allRemovalInfo) == 0 {
return false, nil, errors.New(
"Didn't revoke any devices, but indicated incrementing the key generation")
}
kops := km.config.KeyOps()
for uid, userRemovalInfo := range allRemovalInfo {
if userRemovalInfo.UserRemoved {
km.log.CInfof(ctx, "Rekey %s: removed user %s entirely",
md.TlfID(), uid)
}
for key, serverHalfIDs := range userRemovalInfo.DeviceServerHalfIDs {
km.log.CInfof(ctx, "Rekey %s: removing %d server key halves "+
"for device %s of user %s", md.TlfID(),
len(serverHalfIDs), key, uid)
for _, serverHalfID := range serverHalfIDs {
err := kops.DeleteTLFCryptKeyServerHalf(
ctx, uid, key, serverHalfID)
if err != nil {
return false, nil, err
}
}
}
}
}
pubKey, privKey, tlfCryptKey, err :=
km.config.Crypto().MakeRandomTLFKeys()
if err != nil {
return false, nil, err
}
// Get the current TLF crypt key if needed. It's
// symmetrically encrypted and appended to a list for MDv3
// metadata.
var currTLFCryptKey kbfscrypto.TLFCryptKey
if md.StoresHistoricTLFCryptKeys() && currKeyGen >= kbfsmd.FirstValidKeyGen {
flags := getTLFCryptKeyAnyDevice
if promptPaper {
flags |= getTLFCryptKeyPromptPaper
}
var err error
currTLFCryptKey, err = km.getTLFCryptKey(
ctx, md.ReadOnly(), currKeyGen, flags)
if err != nil {
return false, nil, err
}
}
serverHalves, err := md.AddKeyGeneration(km.config.Codec(),
updatedWriterKeys, updatedReaderKeys,
ePubKey, ePrivKey, pubKey, privKey,
currTLFCryptKey, tlfCryptKey)
if err != nil {
return false, nil, err
}
err = km.config.KeyOps().PutTLFCryptKeyServerHalves(ctx, serverHalves)
if err != nil {
return false, nil, err
}
return true, &tlfCryptKey, nil
}