[GITEA] rework long-term authentication

- The current architecture is inherently insecure, because you can
construct the 'secret' cookie value with values that are available in
the database. Thus provides zero protection when a database is
dumped/leaked.
- This patch implements a new architecture that's inspired from: [Paragonie Initiative](https://paragonie.com/blog/2015/04/secure-authentication-php-with-long-term-persistence#secure-remember-me-cookies).
- Integration testing is added to ensure the new mechanism works.
- Removes a setting, because it's not used anymore.

(cherry-pick from eff097448b)

Conflicts:

	modules/context/context_cookie.go
	trivial context conflicts

	routers/web/web.go
	ctx.GetSiteCookie(setting.CookieRememberName) moved from services/auth/middleware.go
This commit is contained in:
Gusted 2023-06-03 15:21:40 +02:00 committed by Earl Warren
parent 3759c1a7c1
commit 51988ef52b
No known key found for this signature in database
GPG key ID: 0579CB2928A78A00
15 changed files with 338 additions and 154 deletions

96
models/auth/auth_token.go Normal file
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@ -0,0 +1,96 @@
// Copyright 2023 The Forgejo Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package auth
import (
"context"
"crypto/sha256"
"encoding/hex"
"fmt"
"time"
"code.gitea.io/gitea/models/db"
"code.gitea.io/gitea/modules/timeutil"
"code.gitea.io/gitea/modules/util"
)
// AuthorizationToken represents a authorization token to a user.
type AuthorizationToken struct {
ID int64 `xorm:"pk autoincr"`
UID int64 `xorm:"INDEX"`
LookupKey string `xorm:"INDEX UNIQUE"`
HashedValidator string
Expiry timeutil.TimeStamp
}
// TableName provides the real table name.
func (AuthorizationToken) TableName() string {
return "forgejo_auth_token"
}
func init() {
db.RegisterModel(new(AuthorizationToken))
}
// IsExpired returns if the authorization token is expired.
func (authToken *AuthorizationToken) IsExpired() bool {
return authToken.Expiry.AsLocalTime().Before(time.Now())
}
// GenerateAuthToken generates a new authentication token for the given user.
// It returns the lookup key and validator values that should be passed to the
// user via a long-term cookie.
func GenerateAuthToken(ctx context.Context, userID int64, expiry timeutil.TimeStamp) (lookupKey, validator string, err error) {
// Request 64 random bytes. The first 32 bytes will be used for the lookupKey
// and the other 32 bytes will be used for the validator.
rBytes, err := util.CryptoRandomBytes(64)
if err != nil {
return "", "", err
}
hexEncoded := hex.EncodeToString(rBytes)
validator, lookupKey = hexEncoded[64:], hexEncoded[:64]
_, err = db.GetEngine(ctx).Insert(&AuthorizationToken{
UID: userID,
Expiry: expiry,
LookupKey: lookupKey,
HashedValidator: HashValidator(rBytes[32:]),
})
return lookupKey, validator, err
}
// FindAuthToken will find a authorization token via the lookup key.
func FindAuthToken(ctx context.Context, lookupKey string) (*AuthorizationToken, error) {
var authToken AuthorizationToken
has, err := db.GetEngine(ctx).Where("lookup_key = ?", lookupKey).Get(&authToken)
if err != nil {
return nil, err
} else if !has {
return nil, fmt.Errorf("lookup key %q: %w", lookupKey, util.ErrNotExist)
}
return &authToken, nil
}
// DeleteAuthToken will delete the authorization token.
func DeleteAuthToken(ctx context.Context, authToken *AuthorizationToken) error {
_, err := db.DeleteByBean(ctx, authToken)
return err
}
// DeleteAuthTokenByUser will delete all authorization tokens for the user.
func DeleteAuthTokenByUser(ctx context.Context, userID int64) error {
if userID == 0 {
return nil
}
_, err := db.DeleteByBean(ctx, &AuthorizationToken{UID: userID})
return err
}
// HashValidator will return a hexified hashed version of the validator.
func HashValidator(validator []byte) string {
h := sha256.New()
h.Write(validator)
return hex.EncodeToString(h.Sum(nil))
}

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@ -380,6 +380,11 @@ func (u *User) SetPassword(passwd string) (err error) {
return nil
}
// Invalidate all authentication tokens for this user.
if err := auth.DeleteAuthTokenByUser(db.DefaultContext, u.ID); err != nil {
return err
}
if u.Salt, err = GetUserSalt(); err != nil {
return err
}

View file

@ -4,16 +4,14 @@
package context
import (
"encoding/hex"
"net/http"
"strings"
auth_model "code.gitea.io/gitea/models/auth"
user_model "code.gitea.io/gitea/models/user"
"code.gitea.io/gitea/modules/setting"
"code.gitea.io/gitea/modules/util"
"code.gitea.io/gitea/modules/timeutil"
"code.gitea.io/gitea/modules/web/middleware"
"github.com/minio/sha256-simd"
"golang.org/x/crypto/pbkdf2"
)
const CookieNameFlash = "gitea_flash"
@ -46,41 +44,13 @@ func (ctx *Context) GetSiteCookie(name string) string {
return middleware.GetSiteCookie(ctx.Req, name)
}
// GetSuperSecureCookie returns given cookie value from request header with secret string.
func (ctx *Context) GetSuperSecureCookie(secret, name string) (string, bool) {
val := ctx.GetSiteCookie(name)
return ctx.CookieDecrypt(secret, val)
}
// CookieDecrypt returns given value from with secret string.
func (ctx *Context) CookieDecrypt(secret, val string) (string, bool) {
if val == "" {
return "", false
}
text, err := hex.DecodeString(val)
// SetLTACookie will generate a LTA token and add it as an cookie.
func (ctx *Context) SetLTACookie(u *user_model.User) error {
days := 86400 * setting.LogInRememberDays
lookup, validator, err := auth_model.GenerateAuthToken(ctx, u.ID, timeutil.TimeStampNow().Add(int64(days)))
if err != nil {
return "", false
return err
}
key := pbkdf2.Key([]byte(secret), []byte(secret), 1000, 16, sha256.New)
text, err = util.AESGCMDecrypt(key, text)
return string(text), err == nil
}
// SetSuperSecureCookie sets given cookie value to response header with secret string.
func (ctx *Context) SetSuperSecureCookie(secret, name, value string, maxAge int) {
text := ctx.CookieEncrypt(secret, value)
ctx.SetSiteCookie(name, text, maxAge)
}
// CookieEncrypt encrypts a given value using the provided secret
func (ctx *Context) CookieEncrypt(secret, value string) string {
key := pbkdf2.Key([]byte(secret), []byte(secret), 1000, 16, sha256.New)
text, err := util.AESGCMEncrypt(key, []byte(value))
if err != nil {
panic("error encrypting cookie: " + err.Error())
}
return hex.EncodeToString(text)
ctx.SetSiteCookie(setting.CookieRememberName, lookup+":"+validator, days)
return nil
}

View file

@ -19,7 +19,6 @@ var (
SecretKey string
InternalToken string // internal access token
LogInRememberDays int
CookieUserName string
CookieRememberName string
ReverseProxyAuthUser string
ReverseProxyAuthEmail string
@ -104,7 +103,6 @@ func loadSecurityFrom(rootCfg ConfigProvider) {
sec := rootCfg.Section("security")
InstallLock = HasInstallLock(rootCfg)
LogInRememberDays = sec.Key("LOGIN_REMEMBER_DAYS").MustInt(7)
CookieUserName = sec.Key("COOKIE_USERNAME").MustString("gitea_awesome")
SecretKey = loadSecret(sec, "SECRET_KEY_URI", "SECRET_KEY")
if SecretKey == "" {
// FIXME: https://github.com/go-gitea/gitea/issues/16832

View file

@ -4,10 +4,6 @@
package util
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"errors"
"io"
"os"
)
@ -40,52 +36,3 @@ func CopyFile(src, dest string) error {
}
return os.Chmod(dest, si.Mode())
}
// AESGCMEncrypt (from legacy package): encrypts plaintext with the given key using AES in GCM mode. should be replaced.
func AESGCMEncrypt(key, plaintext []byte) ([]byte, error) {
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
nonce := make([]byte, gcm.NonceSize())
if _, err := rand.Read(nonce); err != nil {
return nil, err
}
ciphertext := gcm.Seal(nil, nonce, plaintext, nil)
return append(nonce, ciphertext...), nil
}
// AESGCMDecrypt (from legacy package): decrypts ciphertext with the given key using AES in GCM mode. should be replaced.
func AESGCMDecrypt(key, ciphertext []byte) ([]byte, error) {
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
size := gcm.NonceSize()
if len(ciphertext)-size <= 0 {
return nil, errors.New("ciphertext is empty")
}
nonce := ciphertext[:size]
ciphertext = ciphertext[size:]
plainText, err := gcm.Open(nil, nonce, ciphertext, nil)
if err != nil {
return nil, err
}
return plainText, nil
}

View file

@ -4,8 +4,6 @@
package util
import (
"crypto/aes"
"crypto/rand"
"fmt"
"os"
"testing"
@ -37,21 +35,3 @@ func TestCopyFile(t *testing.T) {
assert.NoError(t, err)
assert.Equal(t, testContent, dstContent)
}
func TestAESGCM(t *testing.T) {
t.Parallel()
key := make([]byte, aes.BlockSize)
_, err := rand.Read(key)
assert.NoError(t, err)
plaintext := []byte("this will be encrypted")
ciphertext, err := AESGCMEncrypt(key, plaintext)
assert.NoError(t, err)
decrypted, err := AESGCMDecrypt(key, ciphertext)
assert.NoError(t, err)
assert.Equal(t, plaintext, decrypted)
}

View file

@ -552,18 +552,13 @@ func SubmitInstall(ctx *context.Context) {
u, _ = user_model.GetUserByName(ctx, u.Name)
}
days := 86400 * setting.LogInRememberDays
ctx.SetSiteCookie(setting.CookieUserName, u.Name, days)
ctx.SetSuperSecureCookie(base.EncodeMD5(u.Rands+u.Passwd),
setting.CookieRememberName, u.Name, days)
// Auto-login for admin
if err = ctx.Session.Set("uid", u.ID); err != nil {
if err := ctx.SetLTACookie(u); err != nil {
ctx.RenderWithErr(ctx.Tr("install.save_config_failed", err), tplInstall, &form)
return
}
if err = ctx.Session.Set("uname", u.Name); err != nil {
// Auto-login for admin
if err = ctx.Session.Set("uid", u.ID); err != nil {
ctx.RenderWithErr(ctx.Tr("install.save_config_failed", err), tplInstall, &form)
return
}

View file

@ -5,6 +5,8 @@
package auth
import (
"crypto/subtle"
"encoding/hex"
"errors"
"fmt"
"net/http"
@ -49,21 +51,47 @@ func AutoSignIn(ctx *context.Context) (bool, error) {
return false, nil
}
uname := ctx.GetSiteCookie(setting.CookieUserName)
if len(uname) == 0 {
authCookie := ctx.GetSiteCookie(setting.CookieRememberName)
if len(authCookie) == 0 {
return false, nil
}
isSucceed := false
defer func() {
if !isSucceed {
log.Trace("auto-login cookie cleared: %s", uname)
ctx.DeleteSiteCookie(setting.CookieUserName)
log.Trace("Auto login cookie is cleared: %s", authCookie)
ctx.DeleteSiteCookie(setting.CookieRememberName)
}
}()
u, err := user_model.GetUserByName(ctx, uname)
lookupKey, validator, found := strings.Cut(authCookie, ":")
if !found {
return false, nil
}
authToken, err := auth.FindAuthToken(ctx, lookupKey)
if err != nil {
if errors.Is(err, util.ErrNotExist) {
return false, nil
}
return false, err
}
if authToken.IsExpired() {
err = auth.DeleteAuthToken(ctx, authToken)
return false, err
}
rawValidator, err := hex.DecodeString(validator)
if err != nil {
return false, err
}
if subtle.ConstantTimeCompare([]byte(authToken.HashedValidator), []byte(auth.HashValidator(rawValidator))) == 0 {
return false, nil
}
u, err := user_model.GetUserByID(ctx, authToken.UID)
if err != nil {
if !user_model.IsErrUserNotExist(err) {
return false, fmt.Errorf("GetUserByName: %w", err)
@ -71,17 +99,11 @@ func AutoSignIn(ctx *context.Context) (bool, error) {
return false, nil
}
if val, ok := ctx.GetSuperSecureCookie(
base.EncodeMD5(u.Rands+u.Passwd), setting.CookieRememberName); !ok || val != u.Name {
return false, nil
}
isSucceed = true
if err := updateSession(ctx, nil, map[string]any{
// Set session IDs
"uid": u.ID,
"uname": u.Name,
"uid": authToken.UID,
}); err != nil {
return false, fmt.Errorf("unable to updateSession: %w", err)
}
@ -290,10 +312,10 @@ func handleSignIn(ctx *context.Context, u *user_model.User, remember bool) {
func handleSignInFull(ctx *context.Context, u *user_model.User, remember, obeyRedirect bool) string {
if remember {
days := 86400 * setting.LogInRememberDays
ctx.SetSiteCookie(setting.CookieUserName, u.Name, days)
ctx.SetSuperSecureCookie(base.EncodeMD5(u.Rands+u.Passwd),
setting.CookieRememberName, u.Name, days)
if err := ctx.SetLTACookie(u); err != nil {
ctx.ServerError("GenerateAuthToken", err)
return setting.AppSubURL + "/"
}
}
if err := updateSession(ctx, []string{
@ -306,8 +328,7 @@ func handleSignInFull(ctx *context.Context, u *user_model.User, remember, obeyRe
"twofaRemember",
"linkAccount",
}, map[string]any{
"uid": u.ID,
"uname": u.Name,
"uid": u.ID,
}); err != nil {
ctx.ServerError("RegenerateSession", err)
return setting.AppSubURL + "/"
@ -368,7 +389,6 @@ func getUserName(gothUser *goth.User) string {
func HandleSignOut(ctx *context.Context) {
_ = ctx.Session.Flush()
_ = ctx.Session.Destroy(ctx.Resp, ctx.Req)
ctx.DeleteSiteCookie(setting.CookieUserName)
ctx.DeleteSiteCookie(setting.CookieRememberName)
ctx.Csrf.DeleteCookie(ctx)
middleware.DeleteRedirectToCookie(ctx.Resp)
@ -708,8 +728,7 @@ func handleAccountActivation(ctx *context.Context, user *user_model.User) {
log.Trace("User activated: %s", user.Name)
if err := updateSession(ctx, nil, map[string]any{
"uid": user.ID,
"uname": user.Name,
"uid": user.ID,
}); err != nil {
log.Error("Unable to regenerate session for user: %-v with email: %s: %v", user, user.Email, err)
ctx.ServerError("ActivateUserEmail", err)

View file

@ -1120,8 +1120,7 @@ func handleOAuth2SignIn(ctx *context.Context, source *auth.Source, u *user_model
// we can't sign the user in just yet. Instead, redirect them to the 2FA authentication page.
if !needs2FA {
if err := updateSession(ctx, nil, map[string]any{
"uid": u.ID,
"uname": u.Name,
"uid": u.ID,
}); err != nil {
ctx.ServerError("updateSession", err)
return

View file

@ -54,8 +54,7 @@ func Home(ctx *context.Context) {
}
// Check auto-login.
uname := ctx.GetSiteCookie(setting.CookieUserName)
if len(uname) != 0 {
if len(ctx.GetSiteCookie(setting.CookieRememberName)) != 0 {
ctx.Redirect(setting.AppSubURL + "/user/login")
return
}

View file

@ -78,6 +78,15 @@ func AccountPost(ctx *context.Context) {
ctx.ServerError("UpdateUser", err)
return
}
// Re-generate LTA cookie.
if len(ctx.GetSiteCookie(setting.CookieRememberName)) != 0 {
if err := ctx.SetLTACookie(ctx.Doer); err != nil {
ctx.ServerError("SetLTACookie", err)
return
}
}
log.Trace("User password updated: %s", ctx.Doer.Name)
ctx.Flash.Success(ctx.Tr("settings.change_password_success"))
}

View file

@ -73,10 +73,6 @@ func handleSignIn(resp http.ResponseWriter, req *http.Request, sess SessionStore
if err != nil {
log.Error(fmt.Sprintf("Error setting session: %v", err))
}
err = sess.Set("uname", user.Name)
if err != nil {
log.Error(fmt.Sprintf("Error setting session: %v", err))
}
// Language setting of the user overwrites the one previously set
// If the user does not have a locale set, we save the current one.

View file

@ -149,7 +149,7 @@ func VerifyAuthWithOptions(options *VerifyOptions) func(ctx *context.Context) {
// Redirect to log in page if auto-signin info is provided and has not signed in.
if !options.SignOutRequired && !ctx.IsSigned &&
len(ctx.GetSiteCookie(setting.CookieUserName)) > 0 {
len(ctx.GetSiteCookie(setting.CookieRememberName)) > 0 {
if ctx.Req.URL.Path != "/user/events" {
middleware.SetRedirectToCookie(ctx.Resp, setting.AppSubURL+ctx.Req.URL.RequestURI())
}

View file

@ -0,0 +1,163 @@
// Copyright 2023 The Forgejo Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package integration
import (
"encoding/hex"
"net/http"
"net/url"
"strings"
"testing"
"code.gitea.io/gitea/models/auth"
"code.gitea.io/gitea/models/db"
"code.gitea.io/gitea/models/unittest"
user_model "code.gitea.io/gitea/models/user"
"code.gitea.io/gitea/modules/setting"
"code.gitea.io/gitea/modules/timeutil"
"code.gitea.io/gitea/tests"
"github.com/stretchr/testify/assert"
)
// GetSessionForLTACookie returns a new session with only the LTA cookie being set.
func GetSessionForLTACookie(t *testing.T, ltaCookie *http.Cookie) *TestSession {
t.Helper()
ch := http.Header{}
ch.Add("Cookie", ltaCookie.String())
cr := http.Request{Header: ch}
session := emptyTestSession(t)
baseURL, err := url.Parse(setting.AppURL)
assert.NoError(t, err)
session.jar.SetCookies(baseURL, cr.Cookies())
return session
}
// GetLTACookieValue returns the value of the LTA cookie.
func GetLTACookieValue(t *testing.T, sess *TestSession) string {
t.Helper()
rememberCookie := sess.GetCookie(setting.CookieRememberName)
assert.NotNil(t, rememberCookie)
cookieValue, err := url.QueryUnescape(rememberCookie.Value)
assert.NoError(t, err)
return cookieValue
}
// TestSessionCookie checks if the session cookie provides authentication.
func TestSessionCookie(t *testing.T) {
defer tests.PrepareTestEnv(t)()
sess := loginUser(t, "user1")
assert.NotNil(t, sess.GetCookie(setting.SessionConfig.CookieName))
req := NewRequest(t, "GET", "/user/settings")
sess.MakeRequest(t, req, http.StatusOK)
}
// TestLTACookie checks if the LTA cookie that's returned is valid, exists in the database
// and provides authentication of no session cookie is present.
func TestLTACookie(t *testing.T) {
defer tests.PrepareTestEnv(t)()
user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
sess := emptyTestSession(t)
req := NewRequestWithValues(t, "POST", "/user/login", map[string]string{
"_csrf": GetCSRF(t, sess, "/user/login"),
"user_name": user.Name,
"password": userPassword,
"remember": "true",
})
sess.MakeRequest(t, req, http.StatusSeeOther)
// Checks if the database entry exist for the user.
ltaCookieValue := GetLTACookieValue(t, sess)
lookupKey, validator, found := strings.Cut(ltaCookieValue, ":")
assert.True(t, found)
rawValidator, err := hex.DecodeString(validator)
assert.NoError(t, err)
unittest.AssertExistsAndLoadBean(t, &auth.AuthorizationToken{LookupKey: lookupKey, HashedValidator: auth.HashValidator(rawValidator), UID: user.ID})
// Check if the LTA cookie it provides authentication.
// If LTA cookie provides authentication /user/login shouldn't return status 200.
session := GetSessionForLTACookie(t, sess.GetCookie(setting.CookieRememberName))
req = NewRequest(t, "GET", "/user/login")
session.MakeRequest(t, req, http.StatusSeeOther)
}
// TestLTAPasswordChange checks that LTA doesn't provide authentication when a
// password change has happened and that the new LTA does provide authentication.
func TestLTAPasswordChange(t *testing.T) {
defer tests.PrepareTestEnv(t)()
user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
sess := loginUserWithPasswordRemember(t, user.Name, userPassword, true)
oldRememberCookie := sess.GetCookie(setting.CookieRememberName)
assert.NotNil(t, oldRememberCookie)
// Make a simple password change.
req := NewRequestWithValues(t, "POST", "/user/settings/account", map[string]string{
"_csrf": GetCSRF(t, sess, "/user/settings/account"),
"old_password": userPassword,
"password": "password2",
"retype": "password2",
})
sess.MakeRequest(t, req, http.StatusSeeOther)
rememberCookie := sess.GetCookie(setting.CookieRememberName)
assert.NotNil(t, rememberCookie)
// Check if the password really changed.
assert.NotEqualValues(t, unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1}).Passwd, user.Passwd)
// /user/settings/account should provide with a new LTA cookie, so check for that.
// If LTA cookie provides authentication /user/login shouldn't return status 200.
session := GetSessionForLTACookie(t, rememberCookie)
req = NewRequest(t, "GET", "/user/login")
session.MakeRequest(t, req, http.StatusSeeOther)
// Check if the old LTA token is invalidated.
session = GetSessionForLTACookie(t, oldRememberCookie)
req = NewRequest(t, "GET", "/user/login")
session.MakeRequest(t, req, http.StatusOK)
}
// TestLTAExpiry tests that the LTA expiry works.
func TestLTAExpiry(t *testing.T) {
defer tests.PrepareTestEnv(t)()
user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
sess := loginUserWithPasswordRemember(t, user.Name, userPassword, true)
ltaCookieValie := GetLTACookieValue(t, sess)
lookupKey, _, found := strings.Cut(ltaCookieValie, ":")
assert.True(t, found)
// Ensure it's not expired.
lta := unittest.AssertExistsAndLoadBean(t, &auth.AuthorizationToken{UID: user.ID, LookupKey: lookupKey})
assert.False(t, lta.IsExpired())
// Manually stub LTA's expiry.
_, err := db.GetEngine(db.DefaultContext).ID(lta.ID).Table("forgejo_auth_token").Cols("expiry").Update(&auth.AuthorizationToken{Expiry: timeutil.TimeStampNow()})
assert.NoError(t, err)
// Ensure it's expired.
lta = unittest.AssertExistsAndLoadBean(t, &auth.AuthorizationToken{UID: user.ID, LookupKey: lookupKey})
assert.True(t, lta.IsExpired())
// Should return 200 OK, because LTA doesn't provide authorization anymore.
session := GetSessionForLTACookie(t, sess.GetCookie(setting.CookieRememberName))
req := NewRequest(t, "GET", "/user/login")
session.MakeRequest(t, req, http.StatusOK)
// Ensure it's deleted.
unittest.AssertNotExistsBean(t, &auth.AuthorizationToken{UID: user.ID, LookupKey: lookupKey})
}

View file

@ -17,6 +17,7 @@ import (
"net/url"
"os"
"path/filepath"
"strconv"
"strings"
"sync/atomic"
"testing"
@ -236,6 +237,12 @@ func loginUser(t testing.TB, userName string) *TestSession {
func loginUserWithPassword(t testing.TB, userName, password string) *TestSession {
t.Helper()
return loginUserWithPasswordRemember(t, userName, password, false)
}
func loginUserWithPasswordRemember(t testing.TB, userName, password string, rememberMe bool) *TestSession {
t.Helper()
req := NewRequest(t, "GET", "/user/login")
resp := MakeRequest(t, req, http.StatusOK)
@ -244,6 +251,7 @@ func loginUserWithPassword(t testing.TB, userName, password string) *TestSession
"_csrf": doc.GetCSRF(),
"user_name": userName,
"password": password,
"remember": strconv.FormatBool(rememberMe),
})
resp = MakeRequest(t, req, http.StatusSeeOther)