Files
mautrix-discord/bridge/crypto.go
Gary Kramlich c5f58afe71 End to bridge encryption implementation
So far this is passing my basic tests, but could use some testing from people
that are much more familiar with how this is supposed to work.

Refs #27
2022-04-27 12:43:12 -05:00

340 lines
10 KiB
Go

package bridge
import (
"fmt"
"runtime/debug"
"time"
"maunium.net/go/maulogger/v2"
"maunium.net/go/mautrix"
"maunium.net/go/mautrix/crypto"
"maunium.net/go/mautrix/event"
"maunium.net/go/mautrix/id"
"gitlab.com/beeper/discord/database"
)
var NoSessionFound = crypto.NoSessionFound
var levelTrace = maulogger.Level{
Name: "TRACE",
Severity: -10,
Color: -1,
}
type Crypto interface {
HandleMemberEvent(*event.Event)
Decrypt(*event.Event) (*event.Event, error)
Encrypt(id.RoomID, event.Type, event.Content) (*event.EncryptedEventContent, error)
WaitForSession(id.RoomID, id.SenderKey, id.SessionID, time.Duration) bool
RequestSession(id.RoomID, id.SenderKey, id.SessionID, id.UserID, id.DeviceID)
ResetSession(id.RoomID)
Init() error
Start()
Stop()
}
type CryptoHelper struct {
bridge *Bridge
client *mautrix.Client
mach *crypto.OlmMachine
store *database.SQLCryptoStore
log maulogger.Logger
baseLog maulogger.Logger
}
func NewCryptoHelper(bridge *Bridge) Crypto {
if !bridge.Config.Bridge.Encryption.Allow {
bridge.log.Debugln("Bridge built with end-to-bridge encryption, but disabled in config")
return nil
}
baseLog := bridge.log.Sub("Crypto")
return &CryptoHelper{
bridge: bridge,
log: baseLog.Sub("Helper"),
baseLog: baseLog,
}
}
func (helper *CryptoHelper) Init() error {
helper.log.Debugln("Initializing end-to-bridge encryption...")
helper.store = database.NewSQLCryptoStore(helper.bridge.db, helper.bridge.as.BotMXID(),
fmt.Sprintf("@%s:%s", helper.bridge.Config.Bridge.FormatUsername("%"), helper.bridge.as.HomeserverDomain))
var err error
helper.client, err = helper.loginBot()
if err != nil {
return err
}
helper.log.Debugln("Logged in as bridge bot with device ID", helper.client.DeviceID)
logger := &cryptoLogger{helper.baseLog}
stateStore := &cryptoStateStore{helper.bridge}
helper.mach = crypto.NewOlmMachine(helper.client, logger, helper.store, stateStore)
helper.mach.AllowKeyShare = helper.allowKeyShare
helper.client.Syncer = &cryptoSyncer{helper.mach}
helper.client.Store = &cryptoClientStore{helper.store}
return helper.mach.Load()
}
func (helper *CryptoHelper) allowKeyShare(device *crypto.DeviceIdentity, info event.RequestedKeyInfo) *crypto.KeyShareRejection {
cfg := helper.bridge.Config.Bridge.Encryption.KeySharing
if !cfg.Allow {
return &crypto.KeyShareRejectNoResponse
} else if device.Trust == crypto.TrustStateBlacklisted {
return &crypto.KeyShareRejectBlacklisted
} else if device.Trust == crypto.TrustStateVerified || !cfg.RequireVerification {
portal := helper.bridge.GetPortalByMXID(info.RoomID)
if portal == nil {
helper.log.Debugfln("Rejecting key request for %s from %s/%s: room is not a portal", info.SessionID, device.UserID, device.DeviceID)
return &crypto.KeyShareRejection{Code: event.RoomKeyWithheldUnavailable, Reason: "Requested room is not a portal room"}
}
user := helper.bridge.GetUserByMXID(device.UserID)
// FIXME reimplement IsInPortal
if !user.Admin /*&& !user.IsInPortal(portal.Key)*/ {
helper.log.Debugfln("Rejecting key request for %s from %s/%s: user is not in portal", info.SessionID, device.UserID, device.DeviceID)
return &crypto.KeyShareRejection{Code: event.RoomKeyWithheldUnauthorized, Reason: "You're not in that portal"}
}
helper.log.Debugfln("Accepting key request for %s from %s/%s", info.SessionID, device.UserID, device.DeviceID)
return nil
}
return &crypto.KeyShareRejectUnverified
}
func (helper *CryptoHelper) loginBot() (*mautrix.Client, error) {
deviceID := helper.store.FindDeviceID()
if len(deviceID) > 0 {
helper.log.Debugln("Found existing device ID for bot in database:", deviceID)
}
client, err := mautrix.NewClient(helper.bridge.as.HomeserverURL, "", "")
if err != nil {
return nil, fmt.Errorf("failed to initialize client: %w", err)
}
client.Logger = helper.baseLog.Sub("Bot")
client.Client = helper.bridge.as.HTTPClient
client.DefaultHTTPRetries = helper.bridge.as.DefaultHTTPRetries
flows, err := client.GetLoginFlows()
if err != nil {
return nil, fmt.Errorf("failed to get supported login flows: %w", err)
}
flow := flows.FirstFlowOfType(mautrix.AuthTypeAppservice, mautrix.AuthTypeHalfyAppservice)
if flow == nil {
return nil, fmt.Errorf("homeserver does not support appservice login")
}
// We set the API token to the AS token here to authenticate the appservice login
// It'll get overridden after the login
client.AccessToken = helper.bridge.as.Registration.AppToken
resp, err := client.Login(&mautrix.ReqLogin{
Type: flow.Type,
Identifier: mautrix.UserIdentifier{Type: mautrix.IdentifierTypeUser, User: string(helper.bridge.as.BotMXID())},
DeviceID: deviceID,
InitialDeviceDisplayName: "Discord Bridge",
StoreCredentials: true,
})
if err != nil {
return nil, fmt.Errorf("failed to log in as bridge bot: %w", err)
}
helper.store.DeviceID = resp.DeviceID
return client, nil
}
func (helper *CryptoHelper) Start() {
helper.log.Debugln("Starting syncer for receiving to-device messages")
err := helper.client.Sync()
if err != nil {
helper.log.Errorln("Fatal error syncing:", err)
} else {
helper.log.Infoln("Bridge bot to-device syncer stopped without error")
}
}
func (helper *CryptoHelper) Stop() {
helper.log.Debugln("CryptoHelper.Stop() called, stopping bridge bot sync")
helper.client.StopSync()
}
func (helper *CryptoHelper) Decrypt(evt *event.Event) (*event.Event, error) {
return helper.mach.DecryptMegolmEvent(evt)
}
func (helper *CryptoHelper) Encrypt(roomID id.RoomID, evtType event.Type, content event.Content) (*event.EncryptedEventContent, error) {
encrypted, err := helper.mach.EncryptMegolmEvent(roomID, evtType, &content)
if err != nil {
if err != crypto.SessionExpired && err != crypto.SessionNotShared && err != crypto.NoGroupSession {
return nil, err
}
helper.log.Debugfln("Got %v while encrypting event for %s, sharing group session and trying again...", err, roomID)
users, err := helper.store.GetRoomMembers(roomID)
if err != nil {
return nil, fmt.Errorf("failed to get room member list: %w", err)
}
err = helper.mach.ShareGroupSession(roomID, users)
if err != nil {
return nil, fmt.Errorf("failed to share group session: %w", err)
}
encrypted, err = helper.mach.EncryptMegolmEvent(roomID, evtType, &content)
if err != nil {
return nil, fmt.Errorf("failed to encrypt event after re-sharing group session: %w", err)
}
}
return encrypted, nil
}
func (helper *CryptoHelper) WaitForSession(roomID id.RoomID, senderKey id.SenderKey, sessionID id.SessionID, timeout time.Duration) bool {
return helper.mach.WaitForSession(roomID, senderKey, sessionID, timeout)
}
func (helper *CryptoHelper) RequestSession(roomID id.RoomID, senderKey id.SenderKey, sessionID id.SessionID, userID id.UserID, deviceID id.DeviceID) {
err := helper.mach.SendRoomKeyRequest(roomID, senderKey, sessionID, "", map[id.UserID][]id.DeviceID{userID: {deviceID}})
if err != nil {
helper.log.Warnfln("Failed to send key request to %s/%s for %s in %s: %v", userID, deviceID, sessionID, roomID, err)
} else {
helper.log.Debugfln("Sent key request to %s/%s for %s in %s", userID, deviceID, sessionID, roomID)
}
}
func (helper *CryptoHelper) ResetSession(roomID id.RoomID) {
err := helper.mach.CryptoStore.RemoveOutboundGroupSession(roomID)
if err != nil {
helper.log.Debugfln("Error manually removing outbound group session in %s: %v", roomID, err)
}
}
func (helper *CryptoHelper) HandleMemberEvent(evt *event.Event) {
helper.mach.HandleMemberEvent(evt)
}
type cryptoSyncer struct {
*crypto.OlmMachine
}
func (syncer *cryptoSyncer) ProcessResponse(resp *mautrix.RespSync, since string) error {
done := make(chan struct{})
go func() {
defer func() {
if err := recover(); err != nil {
syncer.Log.Error("Processing sync response (%s) panicked: %v\n%s", since, err, debug.Stack())
}
done <- struct{}{}
}()
syncer.Log.Trace("Starting sync response handling (%s)", since)
syncer.ProcessSyncResponse(resp, since)
syncer.Log.Trace("Successfully handled sync response (%s)", since)
}()
select {
case <-done:
case <-time.After(30 * time.Second):
syncer.Log.Warn("Handling sync response (%s) is taking unusually long", since)
}
return nil
}
func (syncer *cryptoSyncer) OnFailedSync(_ *mautrix.RespSync, err error) (time.Duration, error) {
syncer.Log.Error("Error /syncing, waiting 10 seconds: %v", err)
return 10 * time.Second, nil
}
func (syncer *cryptoSyncer) GetFilterJSON(_ id.UserID) *mautrix.Filter {
everything := []event.Type{{Type: "*"}}
return &mautrix.Filter{
Presence: mautrix.FilterPart{NotTypes: everything},
AccountData: mautrix.FilterPart{NotTypes: everything},
Room: mautrix.RoomFilter{
IncludeLeave: false,
Ephemeral: mautrix.FilterPart{NotTypes: everything},
AccountData: mautrix.FilterPart{NotTypes: everything},
State: mautrix.FilterPart{NotTypes: everything},
Timeline: mautrix.FilterPart{NotTypes: everything},
},
}
}
type cryptoLogger struct {
int maulogger.Logger
}
func (c *cryptoLogger) Error(message string, args ...interface{}) {
c.int.Errorfln(message, args...)
}
func (c *cryptoLogger) Warn(message string, args ...interface{}) {
c.int.Warnfln(message, args...)
}
func (c *cryptoLogger) Debug(message string, args ...interface{}) {
c.int.Debugfln(message, args...)
}
func (c *cryptoLogger) Trace(message string, args ...interface{}) {
c.int.Logfln(levelTrace, message, args...)
}
type cryptoClientStore struct {
int *database.SQLCryptoStore
}
func (c cryptoClientStore) SaveFilterID(_ id.UserID, _ string) {}
func (c cryptoClientStore) LoadFilterID(_ id.UserID) string { return "" }
func (c cryptoClientStore) SaveRoom(_ *mautrix.Room) {}
func (c cryptoClientStore) LoadRoom(_ id.RoomID) *mautrix.Room { return nil }
func (c cryptoClientStore) SaveNextBatch(_ id.UserID, nextBatchToken string) {
c.int.PutNextBatch(nextBatchToken)
}
func (c cryptoClientStore) LoadNextBatch(_ id.UserID) string {
return c.int.GetNextBatch()
}
var _ mautrix.Storer = (*cryptoClientStore)(nil)
type cryptoStateStore struct {
bridge *Bridge
}
var _ crypto.StateStore = (*cryptoStateStore)(nil)
func (c *cryptoStateStore) IsEncrypted(id id.RoomID) bool {
portal := c.bridge.GetPortalByMXID(id)
if portal != nil {
return portal.Encrypted
}
return false
}
func (c *cryptoStateStore) FindSharedRooms(id id.UserID) []id.RoomID {
return c.bridge.StateStore.FindSharedRooms(id)
}
func (c *cryptoStateStore) GetEncryptionEvent(id.RoomID) *event.EncryptionEventContent {
// TODO implement
return nil
}