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// Copyright 2017 Vector Creations Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package auth implements authentication checks and storage.
package auth
import (
"context"
"crypto/rand"
"database/sql"
"encoding/base64"
"fmt"
"net/http"
"strings"
"github.com/matrix-org/dendrite/appservice/types"
"github.com/matrix-org/dendrite/clientapi/auth/authtypes"
"github.com/matrix-org/dendrite/clientapi/jsonerror"
"github.com/matrix-org/dendrite/clientapi/userutil"
"github.com/matrix-org/dendrite/internal/config"
"github.com/matrix-org/util"
)
// OWASP recommends at least 128 bits of entropy for tokens: https://www.owasp.org/index.php/Insufficient_Session-ID_Length
// 32 bytes => 256 bits
var tokenByteLength = 32
// DeviceDatabase represents a device database.
type DeviceDatabase interface {
// Look up the device matching the given access token.
GetDeviceByAccessToken(ctx context.Context, token string) (*authtypes.Device, error)
}
// AccountDatabase represents an account database.
type AccountDatabase interface {
// Look up the account matching the given localpart.
GetAccountByLocalpart(ctx context.Context, localpart string) (*authtypes.Account, error)
}
// Data contains information required to authenticate a request.
type Data struct {
AccountDB AccountDatabase
DeviceDB DeviceDatabase
// AppServices is the list of all registered AS
AppServices []config.ApplicationService
}
// VerifyUserFromRequest authenticates the HTTP request,
// on success returns Device of the requester.
// Finds local user or an application service user.
// Note: For an AS user, AS dummy device is returned.
// On failure returns an JSON error response which can be sent to the client.
func VerifyUserFromRequest(
req *http.Request, data Data,
) (*authtypes.Device, *util.JSONResponse) {
// Try to find the Application Service user
token, err := ExtractAccessToken(req)
if err != nil {
return nil, &util.JSONResponse{
Code: http.StatusUnauthorized,
JSON: jsonerror.MissingToken(err.Error()),
}
}
// Search for app service with given access_token
var appService *config.ApplicationService
for _, as := range data.AppServices {
if as.ASToken == token {
appService = &as
break
}
}
if appService != nil {
// Create a dummy device for AS user
dev := authtypes.Device{
// Use AS dummy device ID
ID: types.AppServiceDeviceID,
// AS dummy device has AS's token.
AccessToken: token,
}
userID := req.URL.Query().Get("user_id")
localpart, err := userutil.ParseUsernameParam(userID, nil)
if err != nil {
return nil, &util.JSONResponse{
Code: http.StatusBadRequest,
JSON: jsonerror.InvalidUsername(err.Error()),
}
}
if localpart != "" { // AS is masquerading as another user
// Verify that the user is registered
account, err := data.AccountDB.GetAccountByLocalpart(req.Context(), localpart)
// Verify that account exists & appServiceID matches
if err == nil && account.AppServiceID == appService.ID {
// Set the userID of dummy device
dev.UserID = userID
return &dev, nil
}
return nil, &util.JSONResponse{
Code: http.StatusForbidden,
JSON: jsonerror.Forbidden("Application service has not registered this user"),
}
}
// AS is not masquerading as any user, so use AS's sender_localpart
dev.UserID = appService.SenderLocalpart
return &dev, nil
}
// Try to find local user from device database
dev, devErr := verifyAccessToken(req, data.DeviceDB)
if devErr == nil {
return dev, verifyUserParameters(req)
}
return nil, &util.JSONResponse{
Code: http.StatusUnauthorized,
JSON: jsonerror.UnknownToken("Unrecognized access token"), // nolint: misspell
}
}
// verifyUserParameters ensures that a request coming from a regular user is not
// using any query parameters reserved for an application service
func verifyUserParameters(req *http.Request) *util.JSONResponse {
if req.URL.Query().Get("ts") != "" {
return &util.JSONResponse{
Code: http.StatusBadRequest,
JSON: jsonerror.Unknown("parameter 'ts' not allowed without valid parameter 'access_token'"),
}
}
return nil
}
// verifyAccessToken verifies that an access token was supplied in the given HTTP request
// and returns the device it corresponds to. Returns resErr (an error response which can be
// sent to the client) if the token is invalid or there was a problem querying the database.
func verifyAccessToken(req *http.Request, deviceDB DeviceDatabase) (device *authtypes.Device, resErr *util.JSONResponse) {
token, err := ExtractAccessToken(req)
if err != nil {
resErr = &util.JSONResponse{
Code: http.StatusUnauthorized,
JSON: jsonerror.MissingToken(err.Error()),
}
return
}
device, err = deviceDB.GetDeviceByAccessToken(req.Context(), token)
if err != nil {
if err == sql.ErrNoRows {
resErr = &util.JSONResponse{
Code: http.StatusUnauthorized,
JSON: jsonerror.UnknownToken("Unknown token"),
}
} else {
util.GetLogger(req.Context()).WithError(err).Error("deviceDB.GetDeviceByAccessToken failed")
jsonErr := jsonerror.InternalServerError()
resErr = &jsonErr
}
}
return
}
// GenerateAccessToken creates a new access token. Returns an error if failed to generate
// random bytes.
func GenerateAccessToken() (string, error) {
b := make([]byte, tokenByteLength)
if _, err := rand.Read(b); err != nil {
return "", err
}
// url-safe no padding
return base64.RawURLEncoding.EncodeToString(b), nil
}
// ExtractAccessToken from a request, or return an error detailing what went wrong. The
// error message MUST be human-readable and comprehensible to the client.
func ExtractAccessToken(req *http.Request) (string, error) {
// cf https://github.com/matrix-org/synapse/blob/v0.19.2/synapse/api/auth.py#L631
authBearer := req.Header.Get("Authorization")
queryToken := req.URL.Query().Get("access_token")
if authBearer != "" && queryToken != "" {
return "", fmt.Errorf("mixing Authorization headers and access_token query parameters")
}
if queryToken != "" {
return queryToken, nil
}
if authBearer != "" {
parts := strings.SplitN(authBearer, " ", 2)
if len(parts) != 2 || parts[0] != "Bearer" {
return "", fmt.Errorf("invalid Authorization header")
}
return parts[1], nil
}
return "", fmt.Errorf("missing access token")
}
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