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replace http basic auth for web interfaces with session cookie & csrf-based auth

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the http basic auth we had was very simple to reason about, and to implement.
but it has a major downside:

there is no way to logout, browsers keep sending credentials. ideally, browsers
themselves would show a button to stop sending credentials.

a related downside: the http auth mechanism doesn't indicate for which server
paths the credentials are.

another downside: the original password is sent to the server with each
request. though sending original passwords to web servers seems to be
considered normal.

our new approach uses session cookies, along with csrf values when we can. the
sessions are server-side managed, automatically extended on each use. this
makes it easy to invalidate sessions and keeps the frontend simpler (than with
long- vs short-term sessions and refreshing). the cookies are httponly,
samesite=strict, scoped to the path of the web interface. cookies are set
"secure" when set over https. the cookie is set by a successful call to Login.
a call to Logout invalidates a session. changing a password invalidates all
sessions for a user, but keeps the session with which the password was changed
alive. the csrf value is also random, and associated with the session cookie.
the csrf must be sent as header for api calls, or as parameter for direct form
posts (where we cannot set a custom header). rest-like calls made directly by
the browser, e.g. for images, don't have a csrf protection. the csrf value is
returned by the Login api call and stored in localstorage.

api calls without credentials return code "user:noAuth", and with bad
credentials return "user:badAuth". the api client recognizes this and triggers
a login. after a login, all auth-failed api calls are automatically retried.
only for "user:badAuth" is an error message displayed in the login form (e.g.
session expired).

in an ideal world, browsers would take care of most session management. a
server would indicate authentication is needed (like http basic auth), and the
browsers uses trusted ui to request credentials for the server & path. the
browser could use safer mechanism than sending original passwords to the
server, such as scram, along with a standard way to create sessions.  for now,
web developers have to do authentication themselves: from showing the login
prompt, ensuring the right session/csrf cookies/localstorage/headers/etc are
sent with each request.

webauthn is a newer way to do authentication, perhaps we'll implement it in the
future. though hardware tokens aren't an attractive option for many users, and
it may be overkill as long as we still do old-fashioned authentication in smtp
& imap where passwords can be sent to the server.

for issue #58
This commit is contained in:
Mechiel Lukkien
2024-01-04 13:10:48 +01:00
parent c930a400be
commit 0f8bf2f220
50 changed files with 3560 additions and 832 deletions
Download Patch File Download Diff File Expand all files Collapse all files

226
webaccount/account.go
View File

@ -7,17 +7,16 @@ import (
"archive/zip"
"compress/gzip"
"context"
cryptorand "crypto/rand"
"encoding/base64"
"encoding/json"
"errors"
"fmt"
"io"
"net"
"net/http"
"os"
"path/filepath"
"strings"
"time"
_ "embed"
@ -29,17 +28,13 @@ import (
"github.com/mjl-/mox/config"
"github.com/mjl-/mox/dns"
"github.com/mjl-/mox/metrics"
"github.com/mjl-/mox/mlog"
"github.com/mjl-/mox/mox-"
"github.com/mjl-/mox/moxvar"
"github.com/mjl-/mox/store"
"github.com/mjl-/mox/webauth"
)
func init() {
mox.LimitersInit()
}
var pkglog = mlog.New("webaccount", nil)
//go:embed api.json
@ -60,8 +55,6 @@ var webaccountFile = &mox.WebappFile{
var accountDoc = mustParseAPI("account", accountapiJSON)
var accountSherpaHandler http.Handler
func mustParseAPI(api string, buf []byte) (doc sherpadoc.Section) {
err := json.Unmarshal(buf, &doc)
if err != nil {
@ -70,18 +63,39 @@ func mustParseAPI(api string, buf []byte) (doc sherpadoc.Section) {
return doc
}
var sherpaHandlerOpts *sherpa.HandlerOpts
func makeSherpaHandler(cookiePath string, isForwarded bool) (http.Handler, error) {
return sherpa.NewHandler("/api/", moxvar.Version, Account{cookiePath, isForwarded}, &accountDoc, sherpaHandlerOpts)
}
func init() {
collector, err := sherpaprom.NewCollector("moxaccount", nil)
if err != nil {
pkglog.Fatalx("creating sherpa prometheus collector", err)
}
accountSherpaHandler, err = sherpa.NewHandler("/api/", moxvar.Version, Account{}, &accountDoc, &sherpa.HandlerOpts{Collector: collector, AdjustFunctionNames: "none"})
sherpaHandlerOpts = &sherpa.HandlerOpts{Collector: collector, AdjustFunctionNames: "none", NoCORS: true}
// Just to validate.
_, err = makeSherpaHandler("", false)
if err != nil {
pkglog.Fatalx("sherpa handler", err)
}
}
// Handler returns a handler for the webaccount endpoints, customized for the
// cookiePath.
func Handler(cookiePath string, isForwarded bool) func(w http.ResponseWriter, r *http.Request) {
sh, err := makeSherpaHandler(cookiePath, isForwarded)
return func(w http.ResponseWriter, r *http.Request) {
if err != nil {
http.Error(w, "500 - internal server error - cannot handle requests", http.StatusInternalServerError)
return
}
handle(sh, isForwarded, w, r)
}
}
func xcheckf(ctx context.Context, err error, format string, args ...any) {
if err == nil {
return
@ -109,61 +123,12 @@ func xcheckuserf(ctx context.Context, err error, format string, args ...any) {
// Account exports web API functions for the account web interface. All its
// methods are exported under api/. Function calls require valid HTTP
// Authentication credentials of a user.
type Account struct{}
// CheckAuth checks http basic auth, returns login address and account name if
// valid, and writes http response and returns empty string otherwise.
func CheckAuth(ctx context.Context, log mlog.Log, kind string, w http.ResponseWriter, r *http.Request) (address, account string) {
authResult := "error"
start := time.Now()
var addr *net.TCPAddr
defer func() {
metrics.AuthenticationInc(kind, "httpbasic", authResult)
if authResult == "ok" && addr != nil {
mox.LimiterFailedAuth.Reset(addr.IP, start)
}
}()
var err error
var remoteIP net.IP
addr, err = net.ResolveTCPAddr("tcp", r.RemoteAddr)
if err != nil {
log.Errorx("parsing remote address", err, slog.Any("addr", r.RemoteAddr))
} else if addr != nil {
remoteIP = addr.IP
}
if remoteIP != nil && !mox.LimiterFailedAuth.Add(remoteIP, start, 1) {
metrics.AuthenticationRatelimitedInc(kind)
http.Error(w, "429 - too many auth attempts", http.StatusTooManyRequests)
return "", ""
}
// store.OpenEmailAuth has an auth cache, so we don't bcrypt for every auth attempt.
if auth := r.Header.Get("Authorization"); !strings.HasPrefix(auth, "Basic ") {
} else if authBuf, err := base64.StdEncoding.DecodeString(strings.TrimPrefix(auth, "Basic ")); err != nil {
log.Debugx("parsing base64", err)
} else if t := strings.SplitN(string(authBuf), ":", 2); len(t) != 2 {
log.Debug("bad user:pass form")
} else if acc, err := store.OpenEmailAuth(log, t[0], t[1]); err != nil {
if errors.Is(err, store.ErrUnknownCredentials) {
authResult = "badcreds"
log.Info("failed authentication attempt", slog.String("username", t[0]), slog.Any("remote", remoteIP))
}
log.Errorx("open account", err)
} else {
authResult = "ok"
accName := acc.Name
err := acc.Close()
log.Check(err, "closing account")
return t[0], accName
}
// note: browsers don't display the realm to prevent users getting confused by malicious realm messages.
w.Header().Set("WWW-Authenticate", `Basic realm="mox account - login with account email address and password"`)
http.Error(w, "http 401 - unauthorized - mox account - login with account email address and password", http.StatusUnauthorized)
return "", ""
type Account struct {
cookiePath string // From listener, for setting authentication cookies.
isForwarded bool // From listener, whether we look at X-Forwarded-* headers.
}
func Handle(w http.ResponseWriter, r *http.Request) {
func handle(apiHandler http.Handler, isForwarded bool, w http.ResponseWriter, r *http.Request) {
ctx := context.WithValue(r.Context(), mlog.CidKey, mox.Cid())
log := pkglog.WithContext(ctx).With(slog.String("userauth", ""))
@ -224,29 +189,52 @@ func Handle(w http.ResponseWriter, r *http.Request) {
}
}
_, accName := CheckAuth(ctx, log, "webaccount", w, r)
if accName == "" {
// Response already sent.
// HTML/JS can be retrieved without authentication.
if r.URL.Path == "/" {
switch r.Method {
case "GET", "HEAD":
webaccountFile.Serve(ctx, log, w, r)
default:
http.Error(w, "405 - method not allowed - use get", http.StatusMethodNotAllowed)
}
return
}
if lw, ok := w.(interface{ AddAttr(a slog.Attr) }); ok {
lw.AddAttr(slog.String("authaccount", accName))
isAPI := strings.HasPrefix(r.URL.Path, "/api/")
// Only allow POST for calls, they will not work cross-domain without CORS.
if isAPI && r.URL.Path != "/api/" && r.Method != "POST" {
http.Error(w, "405 - method not allowed - use post", http.StatusMethodNotAllowed)
return
}
var loginAddress, accName string
var sessionToken store.SessionToken
// All other URLs, except the login endpoint require some authentication.
if r.URL.Path != "/api/LoginPrep" && r.URL.Path != "/api/Login" {
var ok bool
isExport := strings.HasPrefix(r.URL.Path, "/export/")
requireCSRF := isAPI || r.URL.Path == "/import" || isExport
accName, sessionToken, loginAddress, ok = webauth.Check(ctx, log, webauth.Accounts, "webaccount", isForwarded, w, r, isAPI, requireCSRF, isExport)
if !ok {
// Response has been written already.
return
}
}
if isAPI {
reqInfo := requestInfo{loginAddress, accName, sessionToken, w, r}
ctx = context.WithValue(ctx, requestInfoCtxKey, reqInfo)
apiHandler.ServeHTTP(w, r.WithContext(ctx))
return
}
switch r.URL.Path {
case "/":
switch r.Method {
default:
http.Error(w, "405 - method not allowed - use get", http.StatusMethodNotAllowed)
case "/export/mail-export-maildir.tgz", "/export/mail-export-maildir.zip", "/export/mail-export-mbox.tgz", "/export/mail-export-mbox.zip":
if r.Method != "POST" {
http.Error(w, "405 - method not allowed - use post", http.StatusMethodNotAllowed)
return
case "GET", "HEAD":
}
webaccountFile.Serve(ctx, log, w, r)
return
case "/mail-export-maildir.tgz", "/mail-export-maildir.zip", "/mail-export-mbox.tgz", "/mail-export-mbox.zip":
maildir := strings.Contains(r.URL.Path, "maildir")
tgz := strings.Contains(r.URL.Path, ".tgz")
@ -330,11 +318,6 @@ func Handle(w http.ResponseWriter, r *http.Request) {
_ = json.NewEncoder(w).Encode(ImportProgress{Token: token})
default:
if strings.HasPrefix(r.URL.Path, "/api/") {
ctx = context.WithValue(ctx, authCtxKey, accName)
accountSherpaHandler.ServeHTTP(w, r.WithContext(ctx))
return
}
http.NotFound(w, r)
}
}
@ -347,7 +330,54 @@ type ImportProgress struct {
type ctxKey string
var authCtxKey ctxKey = "account"
var requestInfoCtxKey ctxKey = "requestInfo"
type requestInfo struct {
LoginAddress string
AccountName string
SessionToken store.SessionToken
Response http.ResponseWriter
Request *http.Request // For Proto and TLS connection state during message submit.
}
// LoginPrep returns a login token, and also sets it as cookie. Both must be
// present in the call to Login.
func (w Account) LoginPrep(ctx context.Context) string {
log := pkglog.WithContext(ctx)
reqInfo := ctx.Value(requestInfoCtxKey).(requestInfo)
var data [8]byte
_, err := cryptorand.Read(data[:])
xcheckf(ctx, err, "generate token")
loginToken := base64.RawURLEncoding.EncodeToString(data[:])
webauth.LoginPrep(ctx, log, "webaccount", w.cookiePath, w.isForwarded, reqInfo.Response, reqInfo.Request, loginToken)
return loginToken
}
// Login returns a session token for the credentials, or fails with error code
// "user:badLogin". Call LoginPrep to get a loginToken.
func (w Account) Login(ctx context.Context, loginToken, username, password string) store.CSRFToken {
log := pkglog.WithContext(ctx)
reqInfo := ctx.Value(requestInfoCtxKey).(requestInfo)
csrfToken, err := webauth.Login(ctx, log, webauth.Accounts, "webaccount", w.cookiePath, w.isForwarded, reqInfo.Response, reqInfo.Request, loginToken, username, password)
if _, ok := err.(*sherpa.Error); ok {
panic(err)
}
xcheckf(ctx, err, "login")
return csrfToken
}
// Logout invalidates the session token.
func (w Account) Logout(ctx context.Context) {
log := pkglog.WithContext(ctx)
reqInfo := ctx.Value(requestInfoCtxKey).(requestInfo)
err := webauth.Logout(ctx, log, webauth.Accounts, "webaccount", w.cookiePath, w.isForwarded, reqInfo.Response, reqInfo.Request, reqInfo.AccountName, reqInfo.SessionToken)
xcheckf(ctx, err, "logout")
}
// SetPassword saves a new password for the account, invalidating the previous password.
// Sessions are not interrupted, and will keep working. New login attempts must use the new password.
@ -357,15 +387,25 @@ func (Account) SetPassword(ctx context.Context, password string) {
if len(password) < 8 {
panic(&sherpa.Error{Code: "user:error", Message: "password must be at least 8 characters"})
}
accountName := ctx.Value(authCtxKey).(string)
acc, err := store.OpenAccount(log, accountName)
reqInfo := ctx.Value(requestInfoCtxKey).(requestInfo)
acc, err := store.OpenAccount(log, reqInfo.AccountName)
xcheckf(ctx, err, "open account")
defer func() {
err := acc.Close()
log.Check(err, "closing account")
}()
// Retrieve session, resetting password invalidates it.
ls, err := store.SessionUse(ctx, log, reqInfo.AccountName, reqInfo.SessionToken, "")
xcheckf(ctx, err, "get session")
err = acc.SetPassword(log, password)
xcheckf(ctx, err, "setting password")
// Session has been invalidated. Add it again.
err = store.SessionAddToken(ctx, log, &ls)
xcheckf(ctx, err, "restoring session after password reset")
}
// Account returns information about the account: full name, the default domain,
@ -373,8 +413,8 @@ func (Account) SetPassword(ctx context.Context, password string) {
// domain). todo: replace with a function that returns the whole account, when
// sherpadoc understands unnamed struct fields.
func (Account) Account(ctx context.Context) (string, dns.Domain, map[string]config.Destination) {
accountName := ctx.Value(authCtxKey).(string)
accConf, ok := mox.Conf.Account(accountName)
reqInfo := ctx.Value(requestInfoCtxKey).(requestInfo)
accConf, ok := mox.Conf.Account(reqInfo.AccountName)
if !ok {
xcheckf(ctx, errors.New("not found"), "looking up account")
}
@ -382,12 +422,12 @@ func (Account) Account(ctx context.Context) (string, dns.Domain, map[string]conf
}
func (Account) AccountSaveFullName(ctx context.Context, fullName string) {
accountName := ctx.Value(authCtxKey).(string)
_, ok := mox.Conf.Account(accountName)
reqInfo := ctx.Value(requestInfoCtxKey).(requestInfo)
_, ok := mox.Conf.Account(reqInfo.AccountName)
if !ok {
xcheckf(ctx, errors.New("not found"), "looking up account")
}
err := mox.AccountFullNameSave(ctx, accountName, fullName)
err := mox.AccountFullNameSave(ctx, reqInfo.AccountName, fullName)
xcheckf(ctx, err, "saving account full name")
}
@ -395,8 +435,8 @@ func (Account) AccountSaveFullName(ctx context.Context, fullName string) {
// OldDest is compared against the current destination. If it does not match, an
// error is returned. Otherwise newDest is saved and the configuration reloaded.
func (Account) DestinationSave(ctx context.Context, destName string, oldDest, newDest config.Destination) {
accountName := ctx.Value(authCtxKey).(string)
accConf, ok := mox.Conf.Account(accountName)
reqInfo := ctx.Value(requestInfoCtxKey).(requestInfo)
accConf, ok := mox.Conf.Account(reqInfo.AccountName)
if !ok {
xcheckf(ctx, errors.New("not found"), "looking up account")
}
@ -414,7 +454,7 @@ func (Account) DestinationSave(ctx context.Context, destName string, oldDest, ne
newDest.HostTLSReports = curDest.HostTLSReports
newDest.DomainTLSReports = curDest.DomainTLSReports
err := mox.DestinationSave(ctx, accountName, destName, newDest)
err := mox.DestinationSave(ctx, reqInfo.AccountName, destName, newDest)
xcheckf(ctx, err, "saving destination")
}