rclone/lib/oauthutil/oauthutil.go
Nick Craig-Wood 349112df6b oauthutil: fix security problem when running with two users on the same machine
Before this change two users could run `rclone config` for the same
backend on the same machine at the same time.

User A would get as far as starting the web server.  User B would then
fail to start the webserver, but it would open the browser on the
/auth URL which would redirect the user to the login.  This would then
cause user B to authenticate to user A's rclone.

This changes fixes the problem in two ways.

Firstly it passes the state to the /auth call before redirecting and
checks it there, erroring with a 403 error if it doesn't match.  This
would have fixed the problem on its own.

Secondly it delays the opening of the web browser until after the auth
webserver has started which prevents the user entering the credentials
if another auth server is running.

Fixes #3573
2019-09-29 10:42:02 +01:00

620 lines
18 KiB
Go

package oauthutil
import (
"context"
"crypto/rand"
"encoding/json"
"fmt"
"html/template"
"net"
"net/http"
"strings"
"sync"
"time"
"github.com/pkg/errors"
"github.com/rclone/rclone/fs"
"github.com/rclone/rclone/fs/config"
"github.com/rclone/rclone/fs/config/configmap"
"github.com/rclone/rclone/fs/fshttp"
"github.com/skratchdot/open-golang/open"
"golang.org/x/oauth2"
)
const (
// TitleBarRedirectURL is the OAuth2 redirect URL to use when the authorization
// code should be returned in the title bar of the browser, with the page text
// prompting the user to copy the code and paste it in the application.
TitleBarRedirectURL = "urn:ietf:wg:oauth:2.0:oob"
// bindPort is the port that we bind the local webserver to
bindPort = "53682"
// bindAddress is binding for local webserver when active
bindAddress = "127.0.0.1:" + bindPort
// RedirectURL is redirect to local webserver when active
RedirectURL = "http://" + bindAddress + "/"
// RedirectPublicURL is redirect to local webserver when active with public name
RedirectPublicURL = "http://localhost.rclone.org:" + bindPort + "/"
// RedirectLocalhostURL is redirect to local webserver when active with localhost
RedirectLocalhostURL = "http://localhost:" + bindPort + "/"
// AuthResponse is a template to handle the redirect URL for oauth requests
AuthResponse = `<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>{{ if .OK }}Success!{{ else }}Failure!{{ end }}</title>
</head>
<body>
<h1>{{ if .OK }}Success!{{ else }}Failure!{{ end }}</h1>
<hr>
<pre style="width: 750px; white-space: pre-wrap;">
{{ if eq .OK false }}
Error: {{ .AuthError.Name }}<br>
{{ if .AuthError.Description }}Description: {{ .AuthError.Description }}<br>{{ end }}
{{ if .AuthError.Code }}Code: {{ .AuthError.Code }}<br>{{ end }}
{{ if .AuthError.HelpURL }}Look here for help: <a href="{{ .AuthError.HelpURL }}">{{ .AuthError.HelpURL }}</a><br>{{ end }}
{{ else }}
{{ if .Code }}
Please copy this code into rclone:
{{ .Code }}
{{ else }}
All done. Please go back to rclone.
{{ end }}
{{ end }}
</pre>
</body>
</html>
`
)
// oldToken contains an end-user's tokens.
// This is the data you must store to persist authentication.
//
// From the original code.google.com/p/goauth2/oauth package - used
// for backwards compatibility in the rclone config file
type oldToken struct {
AccessToken string
RefreshToken string
Expiry time.Time
}
// GetToken returns the token saved in the config file under
// section name.
func GetToken(name string, m configmap.Mapper) (*oauth2.Token, error) {
tokenString, ok := m.Get(config.ConfigToken)
if !ok || tokenString == "" {
return nil, errors.New("empty token found - please run rclone config again")
}
token := new(oauth2.Token)
err := json.Unmarshal([]byte(tokenString), token)
if err != nil {
return nil, err
}
// if has data then return it
if token.AccessToken != "" {
return token, nil
}
// otherwise try parsing as oldToken
oldtoken := new(oldToken)
err = json.Unmarshal([]byte(tokenString), oldtoken)
if err != nil {
return nil, err
}
// Fill in result into new token
token.AccessToken = oldtoken.AccessToken
token.RefreshToken = oldtoken.RefreshToken
token.Expiry = oldtoken.Expiry
// Save new format in config file
err = PutToken(name, m, token, false)
if err != nil {
return nil, err
}
return token, nil
}
// PutToken stores the token in the config file
//
// This saves the config file if it changes
func PutToken(name string, m configmap.Mapper, token *oauth2.Token, newSection bool) error {
tokenBytes, err := json.Marshal(token)
if err != nil {
return err
}
tokenString := string(tokenBytes)
old, ok := m.Get(config.ConfigToken)
if !ok || tokenString != old {
err = config.SetValueAndSave(name, config.ConfigToken, tokenString)
if newSection && err != nil {
fs.Debugf(name, "Added new token to config, still needs to be saved")
} else if err != nil {
fs.Errorf(nil, "Failed to save new token in config file: %v", err)
} else {
fs.Debugf(name, "Saved new token in config file")
}
}
return nil
}
// TokenSource stores updated tokens in the config file
type TokenSource struct {
mu sync.Mutex
name string
m configmap.Mapper
tokenSource oauth2.TokenSource
token *oauth2.Token
config *oauth2.Config
ctx context.Context
expiryTimer *time.Timer // signals whenever the token expires
}
// If token has expired then first try re-reading it from the config
// file in case a concurrently running rclone has updated it already
func (ts *TokenSource) reReadToken() bool {
tokenString, err := config.FileGetFresh(ts.name, config.ConfigToken)
if err != nil {
fs.Debugf(ts.name, "Failed to read token out of config file: %v", err)
return false
}
newToken := new(oauth2.Token)
err = json.Unmarshal([]byte(tokenString), newToken)
if err != nil {
fs.Debugf(ts.name, "Failed to parse token out of config file: %v", err)
return false
}
if !newToken.Valid() {
fs.Debugf(ts.name, "Loaded invalid token from config file - ignoring")
return false
}
fs.Debugf(ts.name, "Loaded fresh token from config file")
ts.token = newToken
ts.tokenSource = nil // invalidate since we changed the token
return true
}
// Token returns a token or an error.
// Token must be safe for concurrent use by multiple goroutines.
// The returned Token must not be modified.
//
// This saves the token in the config file if it has changed
func (ts *TokenSource) Token() (*oauth2.Token, error) {
ts.mu.Lock()
defer ts.mu.Unlock()
var (
token *oauth2.Token
err error
changed = false
)
const maxTries = 5
// Try getting the token a few times
for i := 1; i <= maxTries; i++ {
// Try reading the token from the config file in case it has
// been updated by a concurrent rclone process
if !ts.token.Valid() {
if ts.reReadToken() {
changed = true
}
}
// Make a new token source if required
if ts.tokenSource == nil {
ts.tokenSource = ts.config.TokenSource(ts.ctx, ts.token)
}
token, err = ts.tokenSource.Token()
if err == nil {
break
}
fs.Debugf(ts.name, "Token refresh failed try %d/%d: %v", i, maxTries, err)
time.Sleep(1 * time.Second)
}
if err != nil {
return nil, err
}
changed = changed || (*token != *ts.token)
ts.token = token
if changed {
// Bump on the expiry timer if it is set
if ts.expiryTimer != nil {
ts.expiryTimer.Reset(ts.timeToExpiry())
}
err = PutToken(ts.name, ts.m, token, false)
if err != nil {
return nil, err
}
}
return token, nil
}
// Invalidate invalidates the token
func (ts *TokenSource) Invalidate() {
ts.mu.Lock()
ts.token.AccessToken = ""
ts.mu.Unlock()
}
// timeToExpiry returns how long until the token expires
//
// Call with the lock held
func (ts *TokenSource) timeToExpiry() time.Duration {
t := ts.token
if t == nil {
return 0
}
if t.Expiry.IsZero() {
return 3e9 * time.Second // ~95 years
}
return t.Expiry.Sub(time.Now())
}
// OnExpiry returns a channel which has the time written to it when
// the token expires. Note that there is only one channel so if
// attaching multiple go routines it will only signal to one of them.
func (ts *TokenSource) OnExpiry() <-chan time.Time {
ts.mu.Lock()
defer ts.mu.Unlock()
if ts.expiryTimer == nil {
ts.expiryTimer = time.NewTimer(ts.timeToExpiry())
}
return ts.expiryTimer.C
}
// Check interface satisfied
var _ oauth2.TokenSource = (*TokenSource)(nil)
// Context returns a context with our HTTP Client baked in for oauth2
func Context(client *http.Client) context.Context {
return context.WithValue(context.Background(), oauth2.HTTPClient, client)
}
// overrideCredentials sets the ClientID and ClientSecret from the
// config file if they are not blank.
// If any value is overridden, true is returned.
// the origConfig is copied
func overrideCredentials(name string, m configmap.Mapper, origConfig *oauth2.Config) (newConfig *oauth2.Config, changed bool) {
newConfig = new(oauth2.Config)
*newConfig = *origConfig
changed = false
ClientID, ok := m.Get(config.ConfigClientID)
if ok && ClientID != "" {
newConfig.ClientID = ClientID
changed = true
}
ClientSecret, ok := m.Get(config.ConfigClientSecret)
if ok && ClientSecret != "" {
newConfig.ClientSecret = ClientSecret
changed = true
}
AuthURL, ok := m.Get(config.ConfigAuthURL)
if ok && AuthURL != "" {
newConfig.Endpoint.AuthURL = AuthURL
changed = true
}
TokenURL, ok := m.Get(config.ConfigTokenURL)
if ok && TokenURL != "" {
newConfig.Endpoint.TokenURL = TokenURL
changed = true
}
return newConfig, changed
}
// NewClientWithBaseClient gets a token from the config file and
// configures a Client with it. It returns the client and a
// TokenSource which Invalidate may need to be called on. It uses the
// httpClient passed in as the base client.
func NewClientWithBaseClient(name string, m configmap.Mapper, config *oauth2.Config, baseClient *http.Client) (*http.Client, *TokenSource, error) {
config, _ = overrideCredentials(name, m, config)
token, err := GetToken(name, m)
if err != nil {
return nil, nil, err
}
// Set our own http client in the context
ctx := Context(baseClient)
// Wrap the TokenSource in our TokenSource which saves changed
// tokens in the config file
ts := &TokenSource{
name: name,
m: m,
token: token,
config: config,
ctx: ctx,
}
return oauth2.NewClient(ctx, ts), ts, nil
}
// NewClient gets a token from the config file and configures a Client
// with it. It returns the client and a TokenSource which Invalidate may need to be called on
func NewClient(name string, m configmap.Mapper, oauthConfig *oauth2.Config) (*http.Client, *TokenSource, error) {
return NewClientWithBaseClient(name, m, oauthConfig, fshttp.NewClient(fs.Config))
}
// Config does the initial creation of the token
//
// It may run an internal webserver to receive the results
func Config(id, name string, m configmap.Mapper, config *oauth2.Config, opts ...oauth2.AuthCodeOption) error {
return doConfig(id, name, m, nil, config, true, opts)
}
// ConfigNoOffline does the same as Config but does not pass the
// "access_type=offline" parameter.
func ConfigNoOffline(id, name string, m configmap.Mapper, config *oauth2.Config, opts ...oauth2.AuthCodeOption) error {
return doConfig(id, name, m, nil, config, false, opts)
}
// ConfigErrorCheck does the same as Config, but allows the backend to pass a error handling function
// This function gets called with the request made to rclone as a parameter if no code was found
func ConfigErrorCheck(id, name string, m configmap.Mapper, errorHandler func(*http.Request) AuthError, config *oauth2.Config, opts ...oauth2.AuthCodeOption) error {
return doConfig(id, name, m, errorHandler, config, true, opts)
}
func doConfig(id, name string, m configmap.Mapper, errorHandler func(*http.Request) AuthError, oauthConfig *oauth2.Config, offline bool, opts []oauth2.AuthCodeOption) error {
oauthConfig, changed := overrideCredentials(name, m, oauthConfig)
authorizeOnlyValue, ok := m.Get(config.ConfigAuthorize)
authorizeOnly := ok && authorizeOnlyValue != "" // set if being run by "rclone authorize"
// See if already have a token
tokenString, ok := m.Get("token")
if ok && tokenString != "" {
fmt.Printf("Already have a token - refresh?\n")
if !config.ConfirmWithConfig(m, "config_refresh_token", true) {
return nil
}
}
// Ask the user whether they are using a local machine
isLocal := func() bool {
fmt.Printf("Use auto config?\n")
fmt.Printf(" * Say Y if not sure\n")
fmt.Printf(" * Say N if you are working on a remote or headless machine\n")
return config.ConfirmWithConfig(m, "config_is_local", true)
}
// Detect whether we should use internal web server
useWebServer := false
switch oauthConfig.RedirectURL {
case RedirectURL, RedirectPublicURL, RedirectLocalhostURL:
if changed {
fmt.Printf("Make sure your Redirect URL is set to %q in your custom config.\n", oauthConfig.RedirectURL)
}
useWebServer = true
if authorizeOnly {
break
}
if !isLocal() {
fmt.Printf("For this to work, you will need rclone available on a machine that has a web browser available.\n")
fmt.Printf("Execute the following on your machine (same rclone version recommended) :\n")
if changed {
fmt.Printf("\trclone authorize %q %q %q\n", id, oauthConfig.ClientID, oauthConfig.ClientSecret)
} else {
fmt.Printf("\trclone authorize %q\n", id)
}
fmt.Println("Then paste the result below:")
code := ""
for code == "" {
fmt.Printf("result> ")
code = strings.TrimSpace(config.ReadLine())
}
token := &oauth2.Token{}
err := json.Unmarshal([]byte(code), token)
if err != nil {
return err
}
return PutToken(name, m, token, true)
}
case TitleBarRedirectURL:
useWebServer = authorizeOnly
if !authorizeOnly {
useWebServer = isLocal()
}
if useWebServer {
// copy the config and set to use the internal webserver
configCopy := *oauthConfig
oauthConfig = &configCopy
oauthConfig.RedirectURL = RedirectURL
}
}
// Make random state
stateBytes := make([]byte, 16)
_, err := rand.Read(stateBytes)
if err != nil {
return err
}
state := fmt.Sprintf("%x", stateBytes)
if offline {
opts = append(opts, oauth2.AccessTypeOffline)
}
authURL := oauthConfig.AuthCodeURL(state, opts...)
// Prepare webserver
server := authServer{
state: state,
bindAddress: bindAddress,
authURL: authURL,
errorHandler: errorHandler,
}
if useWebServer {
server.code = make(chan string, 1)
server.err = make(chan error, 1)
err := server.Init()
if err != nil {
return errors.Wrap(err, "failed to start auth webserver")
}
go server.Serve()
defer server.Stop()
authURL = "http://" + bindAddress + "/auth?state=" + state
}
// Generate a URL for the user to visit for authorization.
_ = open.Start(authURL)
fmt.Printf("If your browser doesn't open automatically go to the following link: %s\n", authURL)
fmt.Printf("Log in and authorize rclone for access\n")
var authCode string
if useWebServer {
// Read the code, and exchange it for a token.
fmt.Printf("Waiting for code...\n")
authCode = <-server.code
authError := <-server.err
if authCode != "" {
fmt.Printf("Got code\n")
} else {
if authError != nil {
return authError
}
return errors.New("failed to get code")
}
} else {
// Read the code, and exchange it for a token.
fmt.Printf("Enter verification code> ")
authCode = config.ReadLine()
}
token, err := oauthConfig.Exchange(oauth2.NoContext, authCode)
if err != nil {
return errors.Wrap(err, "failed to get token")
}
// Print code if we do automatic retrieval
if authorizeOnly {
result, err := json.Marshal(token)
if err != nil {
return errors.Wrap(err, "failed to marshal token")
}
fmt.Printf("Paste the following into your remote machine --->\n%s\n<---End paste\n", result)
}
return PutToken(name, m, token, true)
}
// Local web server for collecting auth
type authServer struct {
state string
listener net.Listener
bindAddress string
code chan string
err chan error
authURL string
server *http.Server
errorHandler func(*http.Request) AuthError
}
// AuthError gets returned by the backend's errorHandler function
type AuthError struct {
Name string
Description string
Code string
HelpURL string
}
// AuthResponseData can fill the AuthResponse template
type AuthResponseData struct {
OK bool // Failure or Success?
Code string // code to paste into rclone config
AuthError
}
// Init gets the internal web server ready to receive config details
func (s *authServer) Init() error {
fs.Debugf(nil, "Starting auth server on %s", s.bindAddress)
mux := http.NewServeMux()
s.server = &http.Server{
Addr: s.bindAddress,
Handler: mux,
}
s.server.SetKeepAlivesEnabled(false)
mux.HandleFunc("/favicon.ico", func(w http.ResponseWriter, req *http.Request) {
http.Error(w, "", 404)
return
})
mux.HandleFunc("/auth", func(w http.ResponseWriter, req *http.Request) {
state := req.FormValue("state")
if state != s.state {
fs.Debugf(nil, "State did not match: want %q got %q", s.state, state)
http.Error(w, "State did not match - please try again", 403)
return
}
http.Redirect(w, req, s.authURL, http.StatusTemporaryRedirect)
return
})
mux.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
w.Header().Set("Content-Type", "text/html")
fs.Debugf(nil, "Received request on auth server")
code := req.FormValue("code")
var err error
var t = template.Must(template.New("authResponse").Parse(AuthResponse))
resp := AuthResponseData{AuthError: AuthError{}}
if code != "" {
state := req.FormValue("state")
if state != s.state {
fs.Debugf(nil, "State did not match: want %q got %q", s.state, state)
resp.OK = false
resp.AuthError = AuthError{
Name: "Auth State doesn't match",
}
} else {
fs.Debugf(nil, "Successfully got code")
resp.OK = true
if s.code == nil {
resp.Code = code
}
}
} else {
fs.Debugf(nil, "No code found on request")
var authError AuthError
if s.errorHandler == nil {
authError = AuthError{
Name: "Auth Error",
Description: "No code found returned by remote server.",
}
} else {
authError = s.errorHandler(req)
}
err = fmt.Errorf("Error: %s\nCode: %s\nDescription: %s\nHelp: %s",
authError.Name, authError.Code, authError.Description, authError.HelpURL)
resp.OK = false
resp.AuthError = authError
w.WriteHeader(500)
}
if err := t.Execute(w, resp); err != nil {
fs.Debugf(nil, "Could not execute template for web response.")
}
if s.code != nil {
s.code <- code
s.err <- err
}
})
var err error
s.listener, err = net.Listen("tcp", s.bindAddress)
if err != nil {
return err
}
return nil
}
// Serve the auth server, doesn't return
func (s *authServer) Serve() {
err := s.server.Serve(s.listener)
fs.Debugf(nil, "Closed auth server with error: %v", err)
}
// Stop the auth server by closing its socket
func (s *authServer) Stop() {
fs.Debugf(nil, "Closing auth server")
if s.code != nil {
close(s.code)
s.code = nil
}
_ = s.listener.Close()
// close the server
_ = s.server.Close()
}