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Don't bother verifying signatures, validate key lengths if we can, notifier fixes

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This commit is contained in:
Neil Alexander 2021-08-12 14:42:25 +01:00
parent 64fc48f756
commit 3a80058729
No known key found for this signature in database
GPG key ID: A02A2019A2BB0944
6 changed files with 125 additions and 146 deletions
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6
clientapi/jsonerror/jsonerror.go
View file

@ -131,6 +131,12 @@ func InvalidSignature(msg string) *MatrixError {
return &MatrixError{"M_INVALID_SIGNATURE", msg}
}
// InvalidParam is an error that is returned when a parameter was invalid,
// traditionally with cross-signing.
func InvalidParam(msg string) *MatrixError {
return &MatrixError{"M_INVALID_PARAM", msg}
}
// MissingParam is an error that is returned when a parameter was incorrect,
// traditionally with cross-signing.
func MissingParam(msg string) *MatrixError {

10
clientapi/routing/key_crosssigning.go
View file

@ -73,6 +73,11 @@ func UploadCrossSigningDeviceKeys(
Code: http.StatusBadRequest,
JSON: jsonerror.MissingParam(err.Error()),
}
case err.IsInvalidParam:
return util.JSONResponse{
Code: http.StatusBadRequest,
JSON: jsonerror.InvalidParam(err.Error()),
}
default:
return util.JSONResponse{
Code: http.StatusBadRequest,
@ -110,6 +115,11 @@ func UploadCrossSigningDeviceSignatures(req *http.Request, keyserverAPI api.KeyI
Code: http.StatusBadRequest,
JSON: jsonerror.MissingParam(err.Error()),
}
case err.IsInvalidParam:
return util.JSONResponse{
Code: http.StatusBadRequest,
JSON: jsonerror.InvalidParam(err.Error()),
}
default:
return util.JSONResponse{
Code: http.StatusBadRequest,

1
keyserver/api/api.go
View file

@ -48,6 +48,7 @@ type KeyError struct {
Err string `json:"error"`
IsInvalidSignature bool `json:"is_invalid_signature,omitempty"` // M_INVALID_SIGNATURE
IsMissingParam bool `json:"is_missing_param,omitempty"` // M_MISSING_PARAM
IsInvalidParam bool `json:"is_invalid_param,omitempty"` // M_INVALID_PARAM
}
func (k *KeyError) Error() string {

246
keyserver/internal/cross_signing.go
View file

@ -19,7 +19,6 @@ import (
"context"
"crypto/ed25519"
"database/sql"
"encoding/json"
"fmt"
"strings"
@ -28,6 +27,7 @@ import (
"github.com/matrix-org/dendrite/keyserver/types"
"github.com/matrix-org/gomatrixserverlib"
"github.com/sirupsen/logrus"
"golang.org/x/crypto/curve25519"
)
func sanityCheckKey(key gomatrixserverlib.CrossSigningKey, userID string, purpose gomatrixserverlib.CrossSigningKeyPurpose) error {
@ -46,6 +46,41 @@ func sanityCheckKey(key gomatrixserverlib.CrossSigningKey, userID string, purpos
if tokens[1] != b64 {
return fmt.Errorf("key ID isn't correct")
}
switch tokens[0] {
case "ed25519":
if len(keyData) != ed25519.PublicKeySize {
return fmt.Errorf("ed25519 key is not the correct length")
}
case "curve25519":
if len(keyData) != curve25519.PointSize {
return fmt.Errorf("curve25519 key is not the correct length")
}
default:
// We can't enforce the key length to be correct for an
// algorithm that we don't recognise, so instead we'll
// just make sure that it isn't incredibly excessive.
if len(keyData) > 4096 {
return fmt.Errorf("unknown key type is too long")
}
}
}
// Check to see if the signatures make sense
for _, forOriginUser := range key.Signatures {
for originKeyID, originSignature := range forOriginUser {
switch strings.SplitN(string(originKeyID), ":", 1)[0] {
case "ed25519":
if len(originSignature) != ed25519.SignatureSize {
return fmt.Errorf("ed25519 signature is not the correct length")
}
case "curve25519":
return fmt.Errorf("curve25519 signatures are impossible")
default:
if len(originSignature) > 4096 {
return fmt.Errorf("unknown signature type is too long")
}
}
}
}
// Does the key claim to be from the right user?
@ -70,42 +105,68 @@ func sanityCheckKey(key gomatrixserverlib.CrossSigningKey, userID string, purpos
// nolint:gocyclo
func (a *KeyInternalAPI) PerformUploadDeviceKeys(ctx context.Context, req *api.PerformUploadDeviceKeysRequest, res *api.PerformUploadDeviceKeysResponse) {
var masterKey gomatrixserverlib.Base64Bytes
// Find the keys to store.
byPurpose := map[gomatrixserverlib.CrossSigningKeyPurpose]gomatrixserverlib.CrossSigningKey{}
toStore := types.CrossSigningKeyMap{}
hasMasterKey := false
if len(req.MasterKey.Keys) > 0 {
if err := sanityCheckKey(req.MasterKey, req.UserID, gomatrixserverlib.CrossSigningKeyPurposeMaster); err != nil {
res.Error = &api.KeyError{
Err: "Master key sanity check failed: " + err.Error(),
Err: "Master key sanity check failed: " + err.Error(),
IsInvalidParam: true,
}
return
}
for _, keyData := range req.MasterKey.Keys { // iterates once, because sanityCheckKey requires one key
hasMasterKey = true
masterKey = keyData
byPurpose[gomatrixserverlib.CrossSigningKeyPurposeMaster] = req.MasterKey
for _, key := range req.MasterKey.Keys { // iterates once, see sanityCheckKey
toStore[gomatrixserverlib.CrossSigningKeyPurposeMaster] = key
}
hasMasterKey = true
}
if len(req.SelfSigningKey.Keys) > 0 {
if err := sanityCheckKey(req.SelfSigningKey, req.UserID, gomatrixserverlib.CrossSigningKeyPurposeSelfSigning); err != nil {
res.Error = &api.KeyError{
Err: "Self-signing key sanity check failed: " + err.Error(),
Err: "Self-signing key sanity check failed: " + err.Error(),
IsInvalidParam: true,
}
return
}
byPurpose[gomatrixserverlib.CrossSigningKeyPurposeSelfSigning] = req.SelfSigningKey
for _, key := range req.SelfSigningKey.Keys { // iterates once, see sanityCheckKey
toStore[gomatrixserverlib.CrossSigningKeyPurposeSelfSigning] = key
}
}
if len(req.UserSigningKey.Keys) > 0 {
if err := sanityCheckKey(req.UserSigningKey, req.UserID, gomatrixserverlib.CrossSigningKeyPurposeUserSigning); err != nil {
res.Error = &api.KeyError{
Err: "User-signing key sanity check failed: " + err.Error(),
Err: "User-signing key sanity check failed: " + err.Error(),
IsInvalidParam: true,
}
return
}
byPurpose[gomatrixserverlib.CrossSigningKeyPurposeUserSigning] = req.UserSigningKey
for _, key := range req.UserSigningKey.Keys { // iterates once, see sanityCheckKey
toStore[gomatrixserverlib.CrossSigningKeyPurposeUserSigning] = key
}
}
// If the user hasn't given a new master key, then let's go and get their
// existing keys from the database.
// If there's nothing to do then stop here.
if len(toStore) == 0 {
res.Error = &api.KeyError{
Err: "No keys were supplied in the request",
IsMissingParam: true,
}
return
}
// We can't have a self-signing or user-signing key without a master
// key, so make sure we have one of those.
if !hasMasterKey {
existingKeys, err := a.DB.CrossSigningKeysDataForUser(ctx, req.UserID)
if err != nil {
@ -115,87 +176,20 @@ func (a *KeyInternalAPI) PerformUploadDeviceKeys(ctx context.Context, req *api.P
return
}
masterKey, hasMasterKey = existingKeys[gomatrixserverlib.CrossSigningKeyPurposeMaster]
_, hasMasterKey = existingKeys[gomatrixserverlib.CrossSigningKeyPurposeMaster]
}
// If we still don't have a master key at this point then there's nothing else
// we can do - we've checked both the request and the database.
// If we still can't find a master key for the user then stop the upload.
// This satisfies the "Fails to upload self-signing key without master key" test.
if !hasMasterKey {
res.Error = &api.KeyError{
Err: "No master key was found either in the database or in the request!",
IsMissingParam: true,
}
return
}
// The key ID is basically the key itself.
masterKeyID := gomatrixserverlib.KeyID(fmt.Sprintf("ed25519:%s", masterKey.Encode()))
// Work out which things we need to verify the signatures for.
toVerify := make(map[gomatrixserverlib.CrossSigningKeyPurpose]gomatrixserverlib.CrossSigningKey, 3)
toStore := types.CrossSigningKeyMap{}
if len(req.MasterKey.Keys) > 0 {
toVerify[gomatrixserverlib.CrossSigningKeyPurposeMaster] = req.MasterKey
}
if len(req.SelfSigningKey.Keys) > 0 {
toVerify[gomatrixserverlib.CrossSigningKeyPurposeSelfSigning] = req.SelfSigningKey
}
if len(req.UserSigningKey.Keys) > 0 {
toVerify[gomatrixserverlib.CrossSigningKeyPurposeUserSigning] = req.UserSigningKey
}
if len(toVerify) == 0 {
res.Error = &api.KeyError{
Err: "No supplied keys available for verification",
IsMissingParam: true,
}
return
}
for purpose, key := range toVerify {
// Collect together the key IDs we need to verify with. This will include
// all of the key IDs specified in the signatures.
keyJSON, err := json.Marshal(key)
if err != nil {
res.Error = &api.KeyError{
Err: fmt.Sprintf("The JSON of the key section is invalid: %s", err.Error()),
}
return
}
switch purpose {
case gomatrixserverlib.CrossSigningKeyPurposeMaster:
// The master key might have a signature attached to it from the
// previous key, or from a device key, but there's no real need
// to verify it. Clients will perform key checks when the master
// key changes.
default:
// Sub-keys should be signed by the master key.
if err := gomatrixserverlib.VerifyJSON(req.UserID, masterKeyID, ed25519.PublicKey(masterKey), keyJSON); err != nil {
res.Error = &api.KeyError{
Err: fmt.Sprintf("The %q sub-key failed master key signature verification: %s", purpose, err.Error()),
IsInvalidSignature: true,
}
return
}
}
// If we've reached this point then all the signatures are valid so
// add the key to the list of keys to store.
for _, keyData := range key.Keys { // iterates once, see sanityCheckKey
toStore[purpose] = keyData
}
}
if len(toStore) == 0 {
res.Error = &api.KeyError{
Err: "No supplied keys passed verification",
Err: "No master key was found",
IsMissingParam: true,
}
return
}
// Store the keys.
if err := a.DB.StoreCrossSigningKeysForUser(ctx, req.UserID, toStore); err != nil {
res.Error = &api.KeyError{
Err: fmt.Sprintf("a.DB.StoreCrossSigningKeysForUser: %s", err),
@ -204,7 +198,7 @@ func (a *KeyInternalAPI) PerformUploadDeviceKeys(ctx context.Context, req *api.P
}
// Now upload any signatures that were included with the keys.
for _, key := range toVerify {
for _, key := range byPurpose {
var targetKeyID gomatrixserverlib.KeyID
for targetKey := range key.Keys { // iterates once, see sanityCheckKey
targetKeyID = targetKey
@ -229,11 +223,14 @@ func (a *KeyInternalAPI) PerformUploadDeviceKeys(ctx context.Context, req *api.P
update := eduserverAPI.CrossSigningKeyUpdate{
UserID: req.UserID,
}
if _, ok := toStore[gomatrixserverlib.CrossSigningKeyPurposeMaster]; ok {
update.MasterKey = &req.MasterKey
if mk, ok := byPurpose[gomatrixserverlib.CrossSigningKeyPurposeMaster]; ok {
update.MasterKey = &mk
}
if _, ok := toStore[gomatrixserverlib.CrossSigningKeyPurposeSelfSigning]; ok {
update.SelfSigningKey = &req.SelfSigningKey
if ssk, ok := byPurpose[gomatrixserverlib.CrossSigningKeyPurposeSelfSigning]; ok {
update.SelfSigningKey = &ssk
}
if update.MasterKey == nil && update.SelfSigningKey == nil {
return
}
if err := a.Producer.ProduceSigningKeyUpdate(update); err != nil {
res.Error = &api.KeyError{
@ -297,7 +294,7 @@ func (a *KeyInternalAPI) PerformUploadDeviceSignatures(ctx context.Context, req
}
}
if err := a.processSelfSignatures(ctx, req.UserID, queryRes, selfSignatures); err != nil {
if err := a.processSelfSignatures(ctx, req.UserID, selfSignatures); err != nil {
res.Error = &api.KeyError{
Err: fmt.Sprintf("a.processSelfSignatures: %s", err),
}
@ -310,10 +307,25 @@ func (a *KeyInternalAPI) PerformUploadDeviceSignatures(ctx context.Context, req
}
return
}
// Finally, generate a notification that we updated the signatures.
for userID := range req.Signatures {
if _, host, err := gomatrixserverlib.SplitID('@', userID); err == nil && host == a.ThisServer {
update := eduserverAPI.CrossSigningKeyUpdate{
UserID: userID,
}
if err := a.Producer.ProduceSigningKeyUpdate(update); err != nil {
res.Error = &api.KeyError{
Err: fmt.Sprintf("a.Producer.ProduceSigningKeyUpdate: %s", err),
}
return
}
}
}
}
func (a *KeyInternalAPI) processSelfSignatures(
ctx context.Context, _ string, queryRes *api.QueryKeysResponse,
ctx context.Context, _ string,
signatures map[string]map[gomatrixserverlib.KeyID]gomatrixserverlib.CrossSigningForKeyOrDevice,
) error {
// Here we will process:
@ -324,37 +336,8 @@ func (a *KeyInternalAPI) processSelfSignatures(
for targetKeyID, signature := range forTargetUserID {
switch sig := signature.CrossSigningBody.(type) {
case *gomatrixserverlib.CrossSigningKey:
// The user is signing their master key with one of their devices
// The QueryKeys response should contain the device key hopefully.
// First we need to marshal the blob back into JSON so we can verify
// it.
j, err := json.Marshal(sig)
if err != nil {
return fmt.Errorf("json.Marshal: %w", err)
}
for originUserID, forOriginUserID := range sig.Signatures {
originDeviceKeys, ok := queryRes.DeviceKeys[originUserID]
if !ok {
return fmt.Errorf("missing device keys for user %q", originUserID)
}
for originKeyID, originSig := range forOriginUserID {
var originKey gomatrixserverlib.DeviceKeys
if err := json.Unmarshal(originDeviceKeys[string(originKeyID)], &originKey); err != nil {
return fmt.Errorf("json.Unmarshal: %w", err)
}
originSigningKey, ok := originKey.Keys[originKeyID]
if !ok {
return fmt.Errorf("missing origin signing key %q", originKeyID)
}
originSigningKeyPublic := ed25519.PublicKey(originSigningKey)
if err := gomatrixserverlib.VerifyJSON(originUserID, originKeyID, originSigningKeyPublic, j); err != nil {
return fmt.Errorf("gomatrixserverlib.VerifyJSON: %w", err)
}
if err := a.DB.StoreCrossSigningSigsForTarget(
ctx, originUserID, originKeyID, targetUserID, targetKeyID, originSig,
); err != nil {
@ -364,35 +347,8 @@ func (a *KeyInternalAPI) processSelfSignatures(
}
case *gomatrixserverlib.DeviceKeys:
// The user is signing one of their devices with their self-signing key
// The QueryKeys response should contain the master key hopefully.
// First we need to marshal the blob back into JSON so we can verify
// it.
j, err := json.Marshal(sig)
if err != nil {
return fmt.Errorf("json.Marshal: %w", err)
}
for originUserID, forOriginUserID := range sig.Signatures {
for originKeyID, originSig := range forOriginUserID {
originSelfSigningKeys, ok := queryRes.SelfSigningKeys[originUserID]
if !ok {
return fmt.Errorf("missing self-signing key for user %q", originUserID)
}
var originSelfSigningKeyID gomatrixserverlib.KeyID
var originSelfSigningKey gomatrixserverlib.Base64Bytes
for keyID, key := range originSelfSigningKeys.Keys {
originSelfSigningKeyID, originSelfSigningKey = keyID, key
break
}
originSelfSigningKeyPublic := ed25519.PublicKey(originSelfSigningKey)
if err := gomatrixserverlib.VerifyJSON(originUserID, originSelfSigningKeyID, originSelfSigningKeyPublic, j); err != nil {
return fmt.Errorf("gomatrixserverlib.VerifyJSON: %w", err)
}
if err := a.DB.StoreCrossSigningSigsForTarget(
ctx, originUserID, originKeyID, targetUserID, targetKeyID, originSig,
); err != nil {

6
keyserver/producers/keychange.go
View file

@ -93,7 +93,11 @@ func (p *KeyChange) ProduceSigningKeyUpdate(key eduapi.CrossSigningKeyUpdate) er
m.Key = sarama.StringEncoder(key.UserID)
m.Value = sarama.ByteEncoder(value)
_, _, err = p.Producer.SendMessage(&m)
partition, offset, err := p.Producer.SendMessage(&m)
if err != nil {
return err
}
err = p.DB.StoreKeyChange(context.Background(), partition, offset, key.UserID)
if err != nil {
return err
}

2
sytest-whitelist
View file

@ -554,3 +554,5 @@ Can upload self-signing keys
Fails to upload self-signing keys with no auth
Fails to upload self-signing key without master key
can fetch self-signing keys over federation
Changing master key notifies local users
Changing user-signing key notifies local users