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Merge pull request #6913 from bottlepay/relax-failure-len-check

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htlcswitch: relax failure message length check
This commit is contained in:
Oliver Gugger 2022-12-02 16:00:21 +01:00 committed by GitHub
commit 91c0a19807
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
12 changed files with 318 additions and 27 deletions
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3
channeldb/mp_payment.go
View File

@ -4,6 +4,7 @@ import (
"bytes"
"errors"
"io"
"math"
"time"
"github.com/btcsuite/btcd/btcec/v2"
@ -298,7 +299,7 @@ func deserializeHTLCFailInfo(r io.Reader) (*HTLCFailInfo, error) {
// Read failure.
failureBytes, err := wire.ReadVarBytes(
r, 0, lnwire.FailureMessageLength, "failure",
r, 0, math.MaxUint16, "failure",
)
if err != nil {
return nil, err

4
docs/release-notes/release-notes-0.16.0.md
View File

@ -5,6 +5,10 @@
* Warning messages from peers are now recognized and
[logged](https://github.com/lightningnetwork/lnd/pull/6546) by lnd.
* Decrypt onion failure messages with a [length greater than 256
bytes](https://github.com/lightningnetwork/lnd/pull/6913). This moves LND
closer to being spec compliant.
## RPC
* The `RegisterConfirmationsNtfn` call of the `chainnotifier` RPC sub-server

2
go.mod
View File

@ -31,7 +31,7 @@ require (
github.com/kkdai/bstream v1.0.0
github.com/lightninglabs/neutrino v0.14.2
github.com/lightninglabs/protobuf-hex-display v1.4.3-hex-display
github.com/lightningnetwork/lightning-onion v1.0.2-0.20220211021909-bb84a1ccb0c5
github.com/lightningnetwork/lightning-onion v1.2.1-0.20221202012345-ca23184850a1
github.com/lightningnetwork/lnd/cert v1.1.1
github.com/lightningnetwork/lnd/clock v1.1.0
github.com/lightningnetwork/lnd/healthcheck v1.2.2

4
go.sum
View File

@ -440,8 +440,8 @@ github.com/lightninglabs/neutrino v0.14.2 h1:yrnZUCYMZ5ECtXhgDrzqPq2oX8awoAN2D/c
github.com/lightninglabs/neutrino v0.14.2/go.mod h1:OICUeTCn+4Tu27YRJIpWvvqySxx4oH4vgdP33Sw9RDc=
github.com/lightninglabs/protobuf-hex-display v1.4.3-hex-display h1:RZJ8H4ueU/aQ9pFtx5wqsuD3B/DezrewJeVwDKKYY8E=
github.com/lightninglabs/protobuf-hex-display v1.4.3-hex-display/go.mod h1:2oKOBU042GKFHrdbgGiKax4xVrFiZu51lhacUZQ9MnE=
github.com/lightningnetwork/lightning-onion v1.0.2-0.20220211021909-bb84a1ccb0c5 h1:TkKwqFcQTGYoI+VEqyxA8rxpCin8qDaYX0AfVRinT3k=
github.com/lightningnetwork/lightning-onion v1.0.2-0.20220211021909-bb84a1ccb0c5/go.mod h1:7dDx73ApjEZA0kcknI799m2O5kkpfg4/gr7N092ojNo=
github.com/lightningnetwork/lightning-onion v1.2.1-0.20221202012345-ca23184850a1 h1:Wm0g70gkcAu2pGpNZwfWPSVOY21j8IyYsNewwK4OkT4=
github.com/lightningnetwork/lightning-onion v1.2.1-0.20221202012345-ca23184850a1/go.mod h1:7dDx73ApjEZA0kcknI799m2O5kkpfg4/gr7N092ojNo=
github.com/lightningnetwork/lnd/cert v1.1.1 h1:Nsav0RlIDRbOnzz2Yu69SQlK939IKya3Q2S0mDviIN8=
github.com/lightningnetwork/lnd/cert v1.1.1/go.mod h1:1P46svkkd73oSoeI4zjkVKgZNwGq8bkGuPR8z+5vQUs=
github.com/lightningnetwork/lnd/clock v1.0.1/go.mod h1:KnQudQ6w0IAMZi1SgvecLZQZ43ra2vpDNj7H/aasemg=

86
htlcswitch/failure_test.go Normal file
View File

@ -0,0 +1,86 @@
package htlcswitch
import (
"encoding/hex"
"encoding/json"
"os"
"testing"
"github.com/btcsuite/btcd/btcec/v2"
sphinx "github.com/lightningnetwork/lightning-onion"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/tlv"
"github.com/stretchr/testify/require"
)
// TestLongFailureMessage tests that longer failure messages can be interpreted
// correctly.
func TestLongFailureMessage(t *testing.T) {
t.Parallel()
var testData struct {
SessionKey string
Path []string
Reason string
}
// Use long 1024-byte test vector from BOLT 04.
testDataBytes, err := os.ReadFile("testdata/long_failure_msg.json")
require.NoError(t, err)
require.NoError(t, json.Unmarshal(testDataBytes, &testData))
sessionKeyBytes, _ := hex.DecodeString(testData.SessionKey)
reason, _ := hex.DecodeString(testData.Reason)
sphinxPath := make([]*btcec.PublicKey, len(testData.Path))
for i, sKey := range testData.Path {
bKey, err := hex.DecodeString(sKey)
require.NoError(t, err)
key, err := btcec.ParsePubKey(bKey)
require.NoError(t, err)
sphinxPath[i] = key
}
sessionKey, _ := btcec.PrivKeyFromBytes(sessionKeyBytes)
circuit := &sphinx.Circuit{
SessionKey: sessionKey,
PaymentPath: sphinxPath,
}
errorDecryptor := &SphinxErrorDecrypter{
OnionErrorDecrypter: sphinx.NewOnionErrorDecrypter(circuit),
}
// Assert that the failure message can still be extracted.
failure, err := errorDecryptor.DecryptError(reason)
require.NoError(t, err)
incorrectDetails, ok := failure.msg.(*lnwire.FailIncorrectDetails)
require.True(t, ok)
var value varBytesRecordProducer
extraData := incorrectDetails.ExtraOpaqueData()
typeMap, err := extraData.ExtractRecords(&value)
require.NoError(t, err)
require.Len(t, typeMap, 1)
expectedValue := make([]byte, 300)
for i := range expectedValue {
expectedValue[i] = 128
}
require.Equal(t, expectedValue, value.data)
}
type varBytesRecordProducer struct {
data []byte
}
func (v *varBytesRecordProducer) Record() tlv.Record {
return tlv.MakePrimitiveRecord(34001, &v.data)
}

30
htlcswitch/link.go
View File

@ -2,6 +2,7 @@ package htlcswitch
import (
"bytes"
crand "crypto/rand"
"crypto/sha256"
"fmt"
prand "math/rand"
@ -1850,6 +1851,35 @@ func (l *channelLink) handleUpstreamMsg(msg lnwire.Message) {
}
case *lnwire.UpdateFailHTLC:
// Verify that the failure reason is at least 256 bytes plus
// overhead.
const minimumFailReasonLength = lnwire.FailureMessageLength +
2 + 2 + 32
if len(msg.Reason) < minimumFailReasonLength {
// We've received a reason with a non-compliant length.
// Older nodes happily relay back these failures that
// may originate from a node further downstream.
// Therefore we can't just fail the channel.
//
// We want to be compliant ourselves, so we also can't
// pass back the reason unmodified. And we must make
// sure that we don't hit the magic length check of 260
// bytes in processRemoteSettleFails either.
//
// Because the reason is unreadable for the payer
// anyway, we just replace it by a compliant-length
// series of random bytes.
msg.Reason = make([]byte, minimumFailReasonLength)
_, err := crand.Read(msg.Reason[:])
if err != nil {
l.log.Errorf("Random generation error: %v", err)
return
}
}
// Add fail to the update log.
idx := msg.ID
err := l.channel.ReceiveFailHTLC(idx, msg.Reason[:])
if err != nil {

111
htlcswitch/link_test.go
View File

@ -2255,11 +2255,14 @@ func TestChannelLinkBandwidthConsistency(t *testing.T) {
// With that processed, we'll now generate an HTLC fail (sent by the
// remote peer) to cancel the HTLC we just added. This should return us
// back to the bandwidth of the link right before the HTLC was sent.
err = bobChannel.FailHTLC(bobIndex, []byte("nop"), nil, nil, nil)
reason := make([]byte, 292)
copy(reason, []byte("nop"))
err = bobChannel.FailHTLC(bobIndex, reason, nil, nil, nil)
require.NoError(t, err, "unable to fail htlc")
failMsg := &lnwire.UpdateFailHTLC{
ID: 1,
Reason: lnwire.OpaqueReason([]byte("nop")),
Reason: lnwire.OpaqueReason(reason),
}
aliceLink.HandleChannelUpdate(failMsg)
@ -2431,7 +2434,8 @@ func TestChannelLinkBandwidthConsistency(t *testing.T) {
outgoingChanID: addPkt.outgoingChanID,
outgoingHTLCID: addPkt.outgoingHTLCID,
htlc: &lnwire.UpdateFailHTLC{
ID: 1,
ID: 1,
Reason: reason,
},
obfuscator: NewMockObfuscator(),
}
@ -6606,3 +6610,104 @@ func assertFailureCode(t *testing.T, err error, code lnwire.FailCode) {
code, rtErr.WireMessage().Code())
}
}
// TestChannelLinkShortFailureRelay tests that failure reasons that are too
// short are replaced by a spec-compliant length failure message and relayed
// back.
func TestChannelLinkShortFailureRelay(t *testing.T) {
t.Parallel()
defer timeout()()
const chanAmt = btcutil.SatoshiPerBitcoin * 5
aliceLink, bobChannel, batchTicker, start, _, err :=
newSingleLinkTestHarness(t, chanAmt, 0)
require.NoError(t, err, "unable to create link")
require.NoError(t, start())
coreLink, ok := aliceLink.(*channelLink)
require.True(t, ok)
mockPeer, ok := coreLink.cfg.Peer.(*mockPeer)
require.True(t, ok)
aliceMsgs := mockPeer.sentMsgs
switchChan := make(chan *htlcPacket)
coreLink.cfg.ForwardPackets = func(linkQuit chan struct{}, _ bool,
packets ...*htlcPacket) error {
for _, p := range packets {
switchChan <- p
}
return nil
}
ctx := linkTestContext{
t: t,
aliceLink: aliceLink,
aliceMsgs: aliceMsgs,
bobChannel: bobChannel,
}
// Send and lock in htlc from Alice to Bob.
const htlcID = 0
htlc, _ := generateHtlcAndInvoice(t, htlcID)
ctx.sendHtlcAliceToBob(htlcID, htlc)
ctx.receiveHtlcAliceToBob()
batchTicker <- time.Now()
ctx.receiveCommitSigAliceToBob(1)
ctx.sendRevAndAckBobToAlice()
ctx.sendCommitSigBobToAlice(1)
ctx.receiveRevAndAckAliceToBob()
// Return a short htlc failure from Bob to Alice and lock in.
shortReason := make([]byte, 260)
err = bobChannel.FailHTLC(0, shortReason, nil, nil, nil)
require.NoError(t, err)
aliceLink.HandleChannelUpdate(&lnwire.UpdateFailHTLC{
ID: htlcID,
Reason: shortReason,
})
ctx.sendCommitSigBobToAlice(0)
ctx.receiveRevAndAckAliceToBob()
ctx.receiveCommitSigAliceToBob(0)
ctx.sendRevAndAckBobToAlice()
// Assert that switch gets the fail message.
msg := <-switchChan
htlcFailMsg, ok := msg.htlc.(*lnwire.UpdateFailHTLC)
require.True(t, ok)
// Assert that it is not a converted error.
require.False(t, msg.convertedError)
// Assert that the length is corrected to the spec-compliant length of
// 256 bytes plus overhead.
require.Len(t, htlcFailMsg.Reason, 292)
// Stop the link
aliceLink.Stop()
// Check that no unexpected messages were sent.
select {
case msg := <-aliceMsgs:
require.Fail(t, "did not expect message %T", msg)
case msg := <-switchChan:
require.Fail(t, "did not expect switch message %T", msg)
default:
}
}

19
htlcswitch/mock.go
View File

@ -419,12 +419,16 @@ func (o *mockObfuscator) Reextract(
return nil
}
var fakeHmac = []byte("hmachmachmachmachmachmachmachmac")
func (o *mockObfuscator) EncryptFirstHop(failure lnwire.FailureMessage) (
lnwire.OpaqueReason, error) {
o.failure = failure
var b bytes.Buffer
b.Write(fakeHmac)
if err := lnwire.EncodeFailure(&b, failure, 0); err != nil {
return nil, err
}
@ -436,7 +440,12 @@ func (o *mockObfuscator) IntermediateEncrypt(reason lnwire.OpaqueReason) lnwire.
}
func (o *mockObfuscator) EncryptMalformedError(reason lnwire.OpaqueReason) lnwire.OpaqueReason {
return reason
var b bytes.Buffer
b.Write(fakeHmac)
b.Write(reason)
return b.Bytes()
}
// mockDeobfuscator mock implementation of the failure deobfuscator which
@ -447,7 +456,13 @@ func newMockDeobfuscator() ErrorDecrypter {
return &mockDeobfuscator{}
}
func (o *mockDeobfuscator) DecryptError(reason lnwire.OpaqueReason) (*ForwardingError, error) {
func (o *mockDeobfuscator) DecryptError(reason lnwire.OpaqueReason) (
*ForwardingError, error) {
if !bytes.Equal(reason[:32], fakeHmac) {
return nil, errors.New("fake decryption error")
}
reason = reason[32:]
r := bytes.NewReader(reason)
failure, err := lnwire.DecodeFailure(r, 0)

15
htlcswitch/switch_test.go
View File

@ -1,7 +1,6 @@
package htlcswitch
import (
"bytes"
"crypto/rand"
"crypto/sha256"
"fmt"
@ -23,7 +22,6 @@ import (
"github.com/lightningnetwork/lnd/lntypes"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/ticker"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
@ -4088,10 +4086,10 @@ func TestSwitchHoldForward(t *testing.T) {
expectedFailure := &lnwire.FailInvalidOnionKey{
OnionSHA256: shaOnionBlob,
}
var b bytes.Buffer
require.NoError(t, lnwire.EncodeFailure(&b, expectedFailure, 0))
assert.Equal(t, lnwire.OpaqueReason(b.Bytes()), failPacket.Reason)
fwdErr, err := newMockDeobfuscator().DecryptError(failPacket.Reason)
require.NoError(t, err)
require.Equal(t, expectedFailure, fwdErr.WireMessage())
assertNumCircuits(t, c.s, 0, 0)
@ -5515,10 +5513,13 @@ func testSwitchAliasInterceptFail(t *testing.T, zeroConf bool) {
failHtlc, ok := failPacket.htlc.(*lnwire.UpdateFailHTLC)
require.True(t, ok)
r := bytes.NewReader(failHtlc.Reason)
failure, err := lnwire.DecodeFailure(r, 0)
fwdErr, err := newMockDeobfuscator().DecryptError(
failHtlc.Reason,
)
require.NoError(t, err)
failure := fwdErr.WireMessage()
failureMsg, ok := failure.(*lnwire.FailTemporaryChannelFailure)
require.True(t, ok)

11
htlcswitch/testdata/long_failure_msg.json vendored Normal file
View File

@ -0,0 +1,11 @@
{
"sessionKey": "4141414141414141414141414141414141414141414141414141414141414141",
"path": [
"02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619",
"0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c",
"027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007",
"032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991",
"02edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145"
],
"reason": "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"
}

57
lnwire/onion_error.go
View File

@ -7,6 +7,7 @@ import (
"encoding/binary"
"fmt"
"io"
"io/ioutil"
"github.com/davecgh/go-spew/spew"
"github.com/go-errors/errors"
@ -344,6 +345,9 @@ type FailIncorrectDetails struct {
// height is the block height when the htlc was received.
height uint32
// extraOpaqueData contains additional failure message tlv data.
extraOpaqueData ExtraOpaqueData
}
// NewFailIncorrectDetails makes a new instance of the FailIncorrectDetails
@ -352,8 +356,9 @@ func NewFailIncorrectDetails(amt MilliSatoshi,
height uint32) *FailIncorrectDetails {
return &FailIncorrectDetails{
amount: amt,
height: height,
amount: amt,
height: height,
extraOpaqueData: []byte{},
}
}
@ -367,6 +372,11 @@ func (f *FailIncorrectDetails) Height() uint32 {
return f.height
}
// ExtraOpaqueData returns additional failure message tlv data.
func (f *FailIncorrectDetails) ExtraOpaqueData() ExtraOpaqueData {
return f.extraOpaqueData
}
// Code returns the failure unique code.
//
// NOTE: Part of the FailureMessage interface.
@ -412,7 +422,7 @@ func (f *FailIncorrectDetails) Decode(r io.Reader, pver uint32) error {
return err
}
return nil
return f.extraOpaqueData.Decode(r)
}
// Encode writes the failure in bytes stream.
@ -423,7 +433,11 @@ func (f *FailIncorrectDetails) Encode(w *bytes.Buffer, pver uint32) error {
return err
}
return WriteUint32(w, f.height)
if err := WriteUint32(w, f.height); err != nil {
return err
}
return f.extraOpaqueData.Encode(w)
}
// FailFinalExpiryTooSoon is returned if the cltv_expiry is too low, the final
@ -1222,18 +1236,41 @@ func DecodeFailure(r io.Reader, pver uint32) (FailureMessage, error) {
// is a 2 byte length followed by the payload itself.
var failureLength uint16
if err := ReadElement(r, &failureLength); err != nil {
return nil, fmt.Errorf("unable to read error len: %v", err)
}
if failureLength > FailureMessageLength {
return nil, fmt.Errorf("failure message is too "+
"long: %v", failureLength)
return nil, fmt.Errorf("unable to read failure len: %w", err)
}
failureData := make([]byte, failureLength)
if _, err := io.ReadFull(r, failureData); err != nil {
return nil, fmt.Errorf("unable to full read payload of "+
"%v: %v", failureLength, err)
"%v: %w", failureLength, err)
}
// Read the padding.
var padLength uint16
if err := ReadElement(r, &padLength); err != nil {
return nil, fmt.Errorf("unable to read pad len: %w", err)
}
if _, err := io.CopyN(ioutil.Discard, r, int64(padLength)); err != nil {
return nil, fmt.Errorf("unable to read padding %w", err)
}
// Verify that we are at the end of the stream now.
scratch := make([]byte, 1)
_, err := r.Read(scratch)
if err != io.EOF {
return nil, fmt.Errorf("unexpected failure bytes")
}
// Check the total length. Convert to 32 bits to prevent overflow.
totalLength := uint32(padLength) + uint32(failureLength)
if totalLength < FailureMessageLength {
return nil, fmt.Errorf("failure message too short: "+
"msg=%v, pad=%v, total=%v",
failureLength, padLength, totalLength)
}
// Decode the failure message.
dataReader := bytes.NewReader(failureData)
return DecodeFailureMessage(dataReader, pver)

3
routing/missioncontrol_store.go
View File

@ -5,6 +5,7 @@ import (
"container/list"
"encoding/binary"
"fmt"
"math"
"sync"
"time"
@ -245,7 +246,7 @@ func deserializeResult(k, v []byte) (*paymentResult, error) {
// Read failure.
failureBytes, err := wire.ReadVarBytes(
r, 0, lnwire.FailureMessageLength, "failure",
r, 0, math.MaxUint16, "failure",
)
if err != nil {
return nil, err