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md_util.go
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md_util.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 (
"fmt"
"time"
"github.com/keybase/client/go/kbfs/idutil"
"github.com/keybase/client/go/kbfs/kbfscodec"
"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/logger"
"github.com/keybase/client/go/protocol/keybase1"
"github.com/pkg/errors"
"golang.org/x/net/context"
)
type mdRange struct {
start kbfsmd.Revision
end kbfsmd.Revision
}
func makeRekeyReadErrorHelper(
err error, kmd libkey.KeyMetadata, resolvedHandle *tlfhandle.Handle,
uid keybase1.UID, username kbname.NormalizedUsername) error {
if resolvedHandle.Type() == tlf.Public {
panic("makeRekeyReadError called on public folder")
}
// If the user is not a legitimate reader of the folder, this is a
// normal read access error.
if !resolvedHandle.IsReader(uid) {
return tlfhandle.NewReadAccessError(
resolvedHandle, username, resolvedHandle.GetCanonicalPath())
}
// Otherwise, this folder needs to be rekeyed for this device.
tlfName := resolvedHandle.GetCanonicalName()
hasKeys, hasKeyErr := kmd.HasKeyForUser(uid)
if (hasKeyErr == nil) && hasKeys {
return NeedSelfRekeyError{tlfName, err}
}
return NeedOtherRekeyError{tlfName, err}
}
func makeRekeyReadError(
ctx context.Context, err error, kbpki KBPKI,
syncGetter syncedTlfGetterSetter, kmd libkey.KeyMetadata,
uid keybase1.UID, username kbname.NormalizedUsername) error {
h := kmd.GetTlfHandle()
resolvedHandle, resolveErr := h.ResolveAgain(ctx, kbpki, nil, syncGetter)
if resolveErr != nil {
// Ignore error and pretend h is already fully
// resolved.
resolvedHandle = h
}
return makeRekeyReadErrorHelper(err, kmd, resolvedHandle, uid, username)
}
// Helper which returns nil if the md block is uninitialized or readable by
// the current user. Otherwise an appropriate read access error is returned.
func isReadableOrError(
ctx context.Context, kbpki KBPKI, syncGetter syncedTlfGetterSetter,
md ReadOnlyRootMetadata) error {
if !md.IsInitialized() || md.IsReadable() {
return nil
}
// this should only be the case if we're a new device not yet
// added to the set of reader/writer keys.
session, err := kbpki.GetCurrentSession(ctx)
if err != nil {
return err
}
err = errors.Errorf("%s is not readable by %s (uid:%s)", md.TlfID(),
session.Name, session.UID)
return makeRekeyReadError(
ctx, err, kbpki, syncGetter, md, session.UID, session.Name)
}
func getMDRange(ctx context.Context, config Config, id tlf.ID, bid kbfsmd.BranchID,
start kbfsmd.Revision, end kbfsmd.Revision, mStatus kbfsmd.MergeStatus,
lockBeforeGet *keybase1.LockID) (rmds []ImmutableRootMetadata, err error) {
// The range is invalid. Don't treat as an error though; it just
// indicates that we don't yet know about any revisions.
if start < kbfsmd.RevisionInitial || end < kbfsmd.RevisionInitial {
return nil, nil
}
mdcache := config.MDCache()
var toDownload []mdRange
// Fetch one at a time, and figure out what ranges to fetch as you
// go.
minSlot := int(end-start) + 1
maxSlot := -1
for i := start; i <= end; i++ {
irmd, err := mdcache.Get(id, i, bid)
if err != nil {
if len(toDownload) == 0 ||
toDownload[len(toDownload)-1].end != i-1 {
toDownload = append(toDownload, mdRange{i, i})
}
toDownload[len(toDownload)-1].end = i
irmd = ImmutableRootMetadata{}
} else {
slot := len(rmds)
if slot < minSlot {
minSlot = slot
}
if slot > maxSlot {
maxSlot = slot
}
}
rmds = append(rmds, irmd)
}
// Try to fetch the rest from the server. TODO: parallelize me.
for _, r := range toDownload {
var fetchedRmds []ImmutableRootMetadata
switch mStatus {
case kbfsmd.Merged:
fetchedRmds, err = config.MDOps().GetRange(
ctx, id, r.start, r.end, lockBeforeGet)
case kbfsmd.Unmerged:
fetchedRmds, err = config.MDOps().GetUnmergedRange(
ctx, id, bid, r.start, r.end)
default:
panic(fmt.Sprintf("Unknown merged type: %s", mStatus))
}
if err != nil {
return nil, err
}
for _, rmd := range fetchedRmds {
slot := int(rmd.Revision() - start)
if slot < minSlot {
minSlot = slot
}
if slot > maxSlot {
maxSlot = slot
}
rmds[slot] = rmd
// We don't cache the MD here, since it's already done in
// `MDOpsStandard` for MDs that come from a remote server.
// MDs that come from the local journal don't get cached
// as part of a get, to avoid races as in KBFS-2224.
}
}
if minSlot > maxSlot {
return nil, nil
}
rmds = rmds[minSlot : maxSlot+1]
// check to make sure there are no holes
for i, rmd := range rmds {
if rmd == (ImmutableRootMetadata{}) {
return nil, fmt.Errorf("No %s MD found for revision %d",
mStatus, int(start)+minSlot+i)
}
}
return rmds, nil
}
// getSingleMD returns an MD that is required to exist.
func getSingleMD(ctx context.Context, config Config, id tlf.ID, bid kbfsmd.BranchID,
rev kbfsmd.Revision, mStatus kbfsmd.MergeStatus, lockBeforeGet *keybase1.LockID) (
ImmutableRootMetadata, error) {
rmds, err := getMDRange(
ctx, config, id, bid, rev, rev, mStatus, lockBeforeGet)
if err != nil {
return ImmutableRootMetadata{}, err
}
if len(rmds) != 1 {
return ImmutableRootMetadata{},
fmt.Errorf("Single expected revision %d not found", rev)
}
return rmds[0], nil
}
// MakeCopyWithDecryptedPrivateData makes a copy of the given IRMD,
// decrypting it with the given IRMD with keys.
func MakeCopyWithDecryptedPrivateData(
ctx context.Context, config Config,
irmdToDecrypt, irmdWithKeys ImmutableRootMetadata, uid keybase1.UID) (
rmdDecrypted ImmutableRootMetadata, err error) {
pmd, err := decryptMDPrivateData(
ctx, config.Codec(), config.Crypto(),
config.BlockCache(), config.BlockOps(),
config.KeyManager(), config.KBPKI(), config, config.Mode(), uid,
irmdToDecrypt.GetSerializedPrivateMetadata(),
irmdToDecrypt, irmdWithKeys, config.MakeLogger(""))
if err != nil {
return ImmutableRootMetadata{}, err
}
rmdCopy, err := irmdToDecrypt.deepCopy(config.Codec())
if err != nil {
return ImmutableRootMetadata{}, err
}
rmdCopy.data = pmd
return MakeImmutableRootMetadata(rmdCopy,
irmdToDecrypt.LastModifyingWriterVerifyingKey(),
irmdToDecrypt.MdID(),
irmdToDecrypt.LocalTimestamp(),
irmdToDecrypt.putToServer), nil
}
func getMergedMDUpdatesWithEnd(ctx context.Context, config Config, id tlf.ID,
startRev kbfsmd.Revision, endRev kbfsmd.Revision,
lockBeforeGet *keybase1.LockID) (
mergedRmds []ImmutableRootMetadata, err error) {
// We don't yet know about any revisions yet, so there's no range
// to get.
if startRev < kbfsmd.RevisionInitial {
return nil, nil
}
start := startRev
for {
end := start + maxMDsAtATime - 1 // range is inclusive
if endRev != kbfsmd.RevisionUninitialized && end > endRev {
end = endRev
}
if end < start {
break
}
rmds, err := getMDRange(ctx, config, id, kbfsmd.NullBranchID,
start, end, kbfsmd.Merged, lockBeforeGet)
if err != nil {
return nil, err
}
if len(mergedRmds) > 0 && len(rmds) > 0 {
// Make sure the first new one is a valid successor of the
// last one.
lastRmd := mergedRmds[len(mergedRmds)-1]
err = lastRmd.CheckValidSuccessor(
lastRmd.mdID, rmds[0].ReadOnlyRootMetadata)
if err != nil {
return nil, err
}
}
mergedRmds = append(mergedRmds, rmds...)
// TODO: limit the number of MDs we're allowed to hold in
// memory at any one time?
if len(rmds) < maxMDsAtATime {
break
}
start = end + 1
}
var uid keybase1.UID
// Check the readability of each MD. Because rekeys can append a
// MD revision with the new key, older revisions might not be
// readable until the newer revision, containing the key for this
// device, is processed.
for i, rmd := range mergedRmds {
if err := isReadableOrError(ctx, config.KBPKI(), config, rmd.ReadOnly()); err != nil {
// The right secret key for the given rmd's
// key generation may only be present in the
// most recent rmd.
latestRmd := mergedRmds[len(mergedRmds)-1]
if uid == keybase1.UID("") {
session, err := config.KBPKI().GetCurrentSession(ctx)
if err != nil {
return nil, err
}
uid = session.UID
}
irmdCopy, err := MakeCopyWithDecryptedPrivateData(
ctx, config, rmd, latestRmd, uid)
if err != nil {
return nil, err
}
// Overwrite the cached copy with the new copy. Unlike in
// `getMDRange`, it's safe to put this into the cache
// blindly, since updates coming from our local journal
// would always be readable, and thus not subject to this
// rewrite.
if err := config.MDCache().Put(irmdCopy); err != nil {
return nil, err
}
mergedRmds[i] = irmdCopy
}
}
return mergedRmds, nil
}
// getMergedMDUpdates returns a slice of all the merged MDs for a TLF,
// starting from the given startRev. The returned MDs are the same
// instances that are stored in the MD cache, so they should be
// modified with care.
//
// TODO: Accept a parameter to express that we want copies of the MDs
// instead of the cached versions.
func getMergedMDUpdates(ctx context.Context, config Config, id tlf.ID,
startRev kbfsmd.Revision, lockBeforeGet *keybase1.LockID) (
mergedRmds []ImmutableRootMetadata, err error) {
return getMergedMDUpdatesWithEnd(
ctx, config, id, startRev, kbfsmd.RevisionUninitialized, lockBeforeGet)
}
// getUnmergedMDUpdates returns a slice of the unmerged MDs for a TLF
// and unmerged branch, between the merge point for that branch and
// startRev (inclusive). The returned MDs are the same instances that
// are stored in the MD cache, so they should be modified with care.
// If bid is kbfsmd.NullBranchID, it returns an empty MD list.
//
// TODO: Accept a parameter to express that we want copies of the MDs
// instead of the cached versions.
func getUnmergedMDUpdates(ctx context.Context, config Config, id tlf.ID,
bid kbfsmd.BranchID, startRev kbfsmd.Revision) (
currHead kbfsmd.Revision, unmergedRmds []ImmutableRootMetadata,
err error) {
if bid == kbfsmd.NullBranchID {
// We're not really unmerged, so there's nothing to do.
// TODO: require the caller to avoid making this call if the
// bid isn't set (and change the mdserver behavior in that
// case as well).
return startRev, nil, nil
}
// We don't yet know about any revisions yet, so there's no range
// to get.
if startRev < kbfsmd.RevisionInitial {
return kbfsmd.RevisionUninitialized, nil, nil
}
// walk backwards until we find one that is merged
currHead = startRev
for {
// first look up all unmerged MD revisions older than my current head
startRev := currHead - maxMDsAtATime + 1 // (kbfsmd.Revision is signed)
if startRev < kbfsmd.RevisionInitial {
startRev = kbfsmd.RevisionInitial
}
rmds, err := getMDRange(ctx, config, id, bid, startRev, currHead,
kbfsmd.Unmerged, nil)
if err != nil {
return kbfsmd.RevisionUninitialized, nil, err
}
if len(unmergedRmds) > 0 && len(rmds) > 0 {
// Make sure the first old one is a valid successor of the
// last new one.
lastRmd := rmds[len(rmds)-1]
err = lastRmd.CheckValidSuccessor(
lastRmd.mdID, unmergedRmds[0].ReadOnlyRootMetadata)
if err != nil {
return kbfsmd.RevisionUninitialized, nil, err
}
}
numNew := len(rmds)
// prepend to keep the ordering correct
unmergedRmds = append(rmds, unmergedRmds...)
// on the next iteration, start apply the previous root
if numNew > 0 {
currHead = rmds[0].Revision() - 1
}
if currHead < kbfsmd.RevisionInitial {
return kbfsmd.RevisionUninitialized, nil,
errors.New("ran out of MD updates to unstage")
}
// TODO: limit the number of MDs we're allowed to hold in
// memory at any one time?
if numNew < maxMDsAtATime {
break
}
}
return currHead, unmergedRmds, nil
}
// GetMDRevisionByTime returns the revision number of the earliest
// merged MD of `handle` with a server timestamp greater or equal to
// `serverTime`.
func GetMDRevisionByTime(
ctx context.Context, config Config, handle *tlfhandle.Handle,
serverTime time.Time) (kbfsmd.Revision, error) {
id := handle.TlfID()
if id == tlf.NullID {
return kbfsmd.RevisionUninitialized, errors.Errorf(
"No ID set in handle %s", handle.GetCanonicalPath())
}
md, err := config.MDOps().GetForTLFByTime(ctx, id, serverTime)
if err != nil {
return kbfsmd.RevisionUninitialized, err
}
return md.Revision(), nil
}
// encryptMDPrivateData encrypts the private data of the given
// RootMetadata and makes other modifications to prepare it for
// signing (see signMD below). After this function is called, the
// MetadataID of the RootMetadata's BareRootMetadata can be computed.
func encryptMDPrivateData(
ctx context.Context, codec kbfscodec.Codec, crypto cryptoPure,
signer kbfscrypto.Signer, ekg encryptionKeyGetter, me keybase1.UID,
rmd *RootMetadata) error {
err := rmd.data.checkValid()
if err != nil {
return err
}
brmd := rmd.bareMd
privateData := rmd.data
if brmd.TypeForKeying() == tlf.PublicKeying ||
!brmd.IsWriterMetadataCopiedSet() {
// Record the last writer to modify this writer metadata
brmd.SetLastModifyingWriter(me)
if brmd.TypeForKeying() == tlf.PublicKeying {
// Encode the private metadata
encodedPrivateMetadata, err := codec.Encode(privateData)
if err != nil {
return err
}
brmd.SetSerializedPrivateMetadata(encodedPrivateMetadata)
} else if !brmd.IsWriterMetadataCopiedSet() {
// Encrypt and encode the private metadata
k, err := ekg.GetTLFCryptKeyForEncryption(ctx, rmd)
if err != nil {
return err
}
encryptedPrivateMetadata, err := crypto.EncryptPrivateMetadata(privateData, k)
if err != nil {
return err
}
encodedEncryptedPrivateMetadata, err := codec.Encode(encryptedPrivateMetadata)
if err != nil {
return err
}
brmd.SetSerializedPrivateMetadata(encodedEncryptedPrivateMetadata)
}
// Sign the writer metadata internally. This has to be
// done here, instead of in signMD, since the
// MetadataID may depend on it.
err := brmd.SignWriterMetadataInternally(ctx, codec, signer)
if err != nil {
return err
}
}
// Record the last user to modify this metadata
brmd.SetLastModifyingUser(me)
return nil
}
func getFileBlockForMD(ctx context.Context, bcache BlockCacheSimple, bops BlockOps,
ptr BlockPointer, tlfID tlf.ID, rmdWithKeys libkey.KeyMetadata) (
*FileBlock, error) {
// We don't have a convenient way to fetch the block from here via
// folderBlockOps, so just go directly via the
// BlockCache/BlockOps. No locking around the blocks is needed
// since these change blocks are read-only.
block, err := bcache.Get(ptr)
if err != nil {
block = NewFileBlock()
if err := bops.Get(ctx, rmdWithKeys, ptr, block, TransientEntry); err != nil {
return nil, err
}
}
fblock, ok := block.(*FileBlock)
if !ok {
return nil, NotFileBlockError{ptr, MasterBranch, path{}}
}
return fblock, nil
}
func reembedBlockChanges(ctx context.Context, codec kbfscodec.Codec,
bcache BlockCacheSimple, bops BlockOps, mode InitMode, tlfID tlf.ID,
pmd *PrivateMetadata, rmdWithKeys libkey.KeyMetadata, log logger.Logger) error {
info := pmd.Changes.Info
if info.BlockPointer == zeroPtr {
return nil
}
if !mode.BlockManagementEnabled() {
// Leave the block changes unembedded -- they aren't needed in
// minimal mode since there's no node cache, and thus there
// are no Nodes that needs to be updated due to BlockChange
// pointers in those blocks.
log.CDebugf(ctx, "Skipping block change reembedding in mode: %s",
mode.Type())
return nil
}
// Treat the unembedded block change like a file so we can reuse
// the file reading code.
file := path{FolderBranch{tlfID, MasterBranch},
[]pathNode{{
info.BlockPointer, fmt.Sprintf("<MD with block change pointer %s>",
info.BlockPointer)}}}
getter := func(ctx context.Context, kmd libkey.KeyMetadata, ptr BlockPointer,
p path, rtype blockReqType) (*FileBlock, bool, error) {
block, err := getFileBlockForMD(ctx, bcache, bops, ptr, tlfID, kmd)
if err != nil {
return nil, false, err
}
return block, false, nil
}
cacher := func(_ context.Context, ptr BlockPointer, block Block) error {
return nil
}
// Reading doesn't use crypto or the block splitter, so for now
// just pass in nil. Also, reading doesn't depend on the UID, so
// it's ok to be empty.
var id keybase1.UserOrTeamID
fd := newFileData(file, id, nil, nil, rmdWithKeys, getter, cacher, log)
buf, err := fd.getBytes(ctx, 0, -1)
if err != nil {
return err
}
var unembeddedChanges BlockChanges
err = codec.Decode(buf, &unembeddedChanges)
if err != nil {
return err
}
// We rely on at most one of Info or Ops being non-empty in
// crChains.addOps.
if unembeddedChanges.Info.IsInitialized() {
return errors.New("Unembedded BlockChangesInfo unexpectedly has an initialized Info")
}
// The changes block pointers are implicit ref blocks.
unembeddedChanges.Ops[0].AddRefBlock(info.BlockPointer)
iptrs, err := fd.getIndirectFileBlockInfos(ctx)
if err != nil {
return err
}
for _, iptr := range iptrs {
unembeddedChanges.Ops[0].AddRefBlock(iptr.BlockPointer)
}
pmd.Changes = unembeddedChanges
pmd.cachedChanges.Info = info
return nil
}
func reembedBlockChangesIntoCopyIfNeeded(
ctx context.Context, codec kbfscodec.Codec,
bcache BlockCacheSimple, bops BlockOps, mode InitMode,
rmd ImmutableRootMetadata, log logger.Logger) (
ImmutableRootMetadata, error) {
if rmd.data.Changes.Ops != nil {
return rmd, nil
}
// This might be necessary if the MD was retrieved from the
// cache in between putting it to the server (with unembedded
// block changes), and re-loading the block changes back into
// the MD and re-inserting into the cache.
log.CDebugf(ctx,
"Reembedding block changes for revision %d", rmd.Revision())
rmdCopy, err := rmd.deepCopy(codec)
if err != nil {
return ImmutableRootMetadata{}, err
}
err = reembedBlockChanges(
ctx, codec, bcache, bops, mode, rmd.TlfID(),
&rmdCopy.data, rmd, log)
if err != nil {
return ImmutableRootMetadata{}, err
}
return MakeImmutableRootMetadata(
rmdCopy, rmd.lastWriterVerifyingKey, rmd.mdID,
rmd.localTimestamp, rmd.putToServer), nil
}
// decryptMDPrivateData does not use uid if the handle is a public one.
func decryptMDPrivateData(ctx context.Context, codec kbfscodec.Codec,
crypto Crypto, bcache BlockCache, bops BlockOps,
keyGetter mdDecryptionKeyGetter, teamChecker kbfsmd.TeamMembershipChecker,
osg idutil.OfflineStatusGetter, mode InitMode, uid keybase1.UID,
serializedPrivateMetadata []byte, rmdToDecrypt, rmdWithKeys libkey.KeyMetadata,
log logger.Logger) (PrivateMetadata, error) {
handle := rmdToDecrypt.GetTlfHandle()
var pmd PrivateMetadata
if handle.TypeForKeying() == tlf.PublicKeying {
if err := codec.Decode(serializedPrivateMetadata,
&pmd); err != nil {
return PrivateMetadata{}, err
}
} else {
// decrypt the root data for non-public directories
var encryptedPrivateMetadata kbfscrypto.EncryptedPrivateMetadata
if err := codec.Decode(serializedPrivateMetadata,
&encryptedPrivateMetadata); err != nil {
return PrivateMetadata{}, err
}
k, err := keyGetter.GetTLFCryptKeyForMDDecryption(ctx,
rmdToDecrypt, rmdWithKeys)
if err != nil {
log.CDebugf(ctx, "Couldn't get crypt key for %s (%s): %+v",
handle.GetCanonicalPath(), rmdToDecrypt.TlfID(), err)
isReader, readerErr := isReaderFromHandle(
ctx, handle, teamChecker, osg, uid)
if readerErr != nil {
return PrivateMetadata{}, readerErr
}
_, isSelfRekeyError := err.(NeedSelfRekeyError)
_, isOtherRekeyError := err.(NeedOtherRekeyError)
if isReader && (isOtherRekeyError || isSelfRekeyError) {
// Rekey errors are expected if this client is a
// valid folder participant but doesn't have the
// shared crypt key.
} else {
return PrivateMetadata{}, err
}
} else {
pmd, err = crypto.DecryptPrivateMetadata(
encryptedPrivateMetadata, k)
if err != nil {
return PrivateMetadata{}, err
}
}
}
// Re-embed the block changes if it's needed.
err := reembedBlockChanges(
ctx, codec, bcache, bops, mode, rmdWithKeys.TlfID(),
&pmd, rmdWithKeys, log)
if err != nil {
return PrivateMetadata{}, err
}
return pmd, nil
}