mautrix-go/crypto/devicelist.go

// Copyright (c) 2020 Tulir Asokan
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

package crypto

import (
	"github.com/pkg/errors"

	"maunium.net/go/mautrix"
	"maunium.net/go/mautrix/crypto/olm"
	"maunium.net/go/mautrix/id"
)

var (
	MismatchingDeviceID   = errors.New("mismatching device ID in parameter and keys object")
	MismatchingUserID     = errors.New("mismatching user ID in parameter and keys object")
	MismatchingSigningKey = errors.New("received update for device with different signing key")
	NoSigningKeyFound     = errors.New("didn't find ed25519 signing key")
	NoIdentityKeyFound    = errors.New("didn't find curve25519 identity key")
	InvalidKeySignature   = errors.New("invalid signature on device keys")
)

func (mach *OlmMachine) fetchKeys(users []id.UserID, sinceToken string) (data map[id.UserID]map[id.DeviceID]*DeviceIdentity) {
	req := &mautrix.ReqQueryKeys{
		DeviceKeys: mautrix.DeviceKeysRequest{},
		Timeout:    10 * 1000,
		Token:      sinceToken,
	}
	for _, userID := range users {
		req.DeviceKeys[userID] = mautrix.DeviceIDList{}
	}
	mach.Log.Trace("Querying keys for %v", users)
	resp, err := mach.Client.QueryKeys(req)
	if err != nil {
		mach.Log.Warn("Failed to query keys: %v", err)
		return
	}
	for server, err := range resp.Failures {
		mach.Log.Warn("Query keys failure for %s: %v", server, err)
	}
	mach.Log.Trace("Query key result received with %d users", len(resp.DeviceKeys))
	data = make(map[id.UserID]map[id.DeviceID]*DeviceIdentity)
	for userID, devices := range resp.DeviceKeys {
		delete(req.DeviceKeys, userID)

		newDevices := make(map[id.DeviceID]*DeviceIdentity)
		existingDevices, err := mach.CryptoStore.GetDevices(userID)
		if err != nil {
			mach.Log.Warn("Failed to get existing devices for %s: %v", userID, err)
			existingDevices = make(map[id.DeviceID]*DeviceIdentity)
		}
		mach.Log.Trace("Updating devices for %s, got %d devices, have %d in store", userID, len(devices), len(existingDevices))
		for deviceID, deviceKeys := range devices {
			existing := existingDevices[deviceID]
			mach.Log.Trace("Validating device %s of %s", deviceID, userID)
			newDevice, err := mach.validateDevice(userID, deviceID, deviceKeys, existing)
			if err != nil {
				mach.Log.Error("Failed to validate device %s of %s: %v", deviceID, userID, err)
			} else if newDevice != nil {
				newDevices[deviceID] = newDevice
			}
		}
		mach.Log.Trace("Storing new device list for %s containing %d devices", userID, len(newDevices))
		err = mach.CryptoStore.PutDevices(userID, newDevices)
		if err != nil {
			mach.Log.Warn("Failed to update device list for %s: %v", userID, err)
		}
		data[userID] = newDevices
	}
	for userID := range req.DeviceKeys {
		mach.Log.Warn("Didn't get any keys for user %s", userID)
	}
	return data
}

func (mach *OlmMachine) OnDevicesChanged(userID id.UserID) {
	for _, roomID := range mach.StateStore.FindSharedRooms(userID) {
		mach.Log.Trace("Devices of %s changed, invalidating group session for %s", userID, roomID)
		err := mach.CryptoStore.PopOutboundGroupSession(roomID)
		if err != nil {
			mach.Log.Warn("Failed to invalidate outbound group session of %s on device change for %s: %v", roomID, userID, err)
		}
	}
}

func (mach *OlmMachine) validateDevice(userID id.UserID, deviceID id.DeviceID, deviceKeys mautrix.DeviceKeys, existing *DeviceIdentity) (*DeviceIdentity, error) {
	if deviceID != deviceKeys.DeviceID {
		return nil, MismatchingDeviceID
	} else if userID != deviceKeys.UserID {
		return nil, MismatchingUserID
	}

	signingKey := deviceKeys.Keys.GetEd25519(deviceID)
	identityKey := deviceKeys.Keys.GetCurve25519(deviceID)
	if signingKey == "" {
		return nil, NoSigningKeyFound
	} else if identityKey == "" {
		return nil, NoIdentityKeyFound
	}

	if existing != nil && existing.SigningKey != signingKey {
		return existing, MismatchingSigningKey
	}

	ok, err := olm.VerifySignatureJSON(deviceKeys, userID, deviceID, signingKey)
	if err != nil {
		return existing, errors.Wrap(err, "failed to verify signature")
	} else if !ok {
		return existing, InvalidKeySignature
	}

	name, ok := deviceKeys.Unsigned["device_display_name"].(string)
	if !ok {
		name = string(deviceID)
	}

	return &DeviceIdentity{
		UserID:      userID,
		DeviceID:    deviceID,
		IdentityKey: identityKey,
		SigningKey:  signingKey,
		Trust:       TrustStateUnset,
		Name:        name,
		Deleted:     false,
	}, nil
}