fix: extend forgejo_auth_token table

- Add a `purpose` column, this allows the `forgejo_auth_token` table to
be used by other parts of Forgejo, while still enjoying the
no-compromise architecture.
- Remove the 'roll your own crypto' time limited code functions and
migrate them to the `forgejo_auth_token` table. This migration ensures
generated codes can only be used for their purpose and ensure they are
invalidated after their usage by deleting it from the database, this
also should help making auditing of the security code easier, as we're
no longer trying to stuff a lot of data into a HMAC construction.
-Helper functions are rewritten to ensure a safe-by-design approach to
these tokens.
- Add the `forgejo_auth_token` to dbconsistency doctor and add it to the
`deleteUser` function.
- TODO: Add cron job to delete expired authorization tokens.
- Unit and integration tests added.

(cherry picked from commit 1ce33aa)

v9: Removed migration - XORM can handle this case automatically without
migration. Add `DEFAULT 'long_term_authorization'`.

Author: Gusted

models/auth/auth_token.go

@@ -15,12 +15,31 @@ import (
 	"code.gitea.io/gitea/modules/util"
 )
 
+type AuthorizationPurpose string
+
+var (
+	// Used to store long term authorization tokens.
+	LongTermAuthorization AuthorizationPurpose = "long_term_authorization"
+
+	// Used to activate a user account.
+	UserActivation AuthorizationPurpose = "user_activation"
+
+	// Used to reset the password.
+	PasswordReset AuthorizationPurpose = "password_reset"
+)
+
+// Used to activate the specified email address for a user.
+func EmailActivation(email string) AuthorizationPurpose {
+	return AuthorizationPurpose("email_activation:" + email)
+}
+
 // 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
+	Purpose         AuthorizationPurpose `xorm:"NOT NULL DEFAULT 'long_term_authorization'"`
 	Expiry          timeutil.TimeStamp
 }
 
@@ -41,7 +60,7 @@ func (authToken *AuthorizationToken) IsExpired() bool {
 // 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) {
+func GenerateAuthToken(ctx context.Context, userID int64, expiry timeutil.TimeStamp, purpose AuthorizationPurpose) (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)
@@ -56,14 +75,15 @@ func GenerateAuthToken(ctx context.Context, userID int64, expiry timeutil.TimeSt
 		Expiry:          expiry,
 		LookupKey:       lookupKey,
 		HashedValidator: HashValidator(rBytes[32:]),
+		Purpose:         purpose,
 	})
 	return lookupKey, validator, err
 }
 
 // FindAuthToken will find a authorization token via the lookup key.
-func FindAuthToken(ctx context.Context, lookupKey string) (*AuthorizationToken, error) {
+func FindAuthToken(ctx context.Context, lookupKey string, purpose AuthorizationPurpose) (*AuthorizationToken, error) {
 	var authToken AuthorizationToken
-	has, err := db.GetEngine(ctx).Where("lookup_key = ?", lookupKey).Get(&authToken)
+	has, err := db.GetEngine(ctx).Where("lookup_key = ? AND purpose = ?", lookupKey, purpose).Get(&authToken)
 	if err != nil {
 		return nil, err
 	} else if !has {

models/user/email_address.go

@@ -10,10 +10,8 @@ import (
 	"net/mail"
 	"regexp"
 	"strings"
-	"time"
 
 	"code.gitea.io/gitea/models/db"
-	"code.gitea.io/gitea/modules/base"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/optional"
 	"code.gitea.io/gitea/modules/setting"
@@ -307,23 +305,6 @@ func updateActivation(ctx context.Context, email *EmailAddress, activate bool) e
 	return UpdateUserCols(ctx, user, "rands")
 }
 
-// VerifyActiveEmailCode verifies active email code when active account
-func VerifyActiveEmailCode(ctx context.Context, code, email string) *EmailAddress {
-	if user := GetVerifyUser(ctx, code); user != nil {
-		// time limit code
-		prefix := code[:base.TimeLimitCodeLength]
-		data := fmt.Sprintf("%d%s%s%s%s", user.ID, email, user.LowerName, user.Passwd, user.Rands)
-
-		if base.VerifyTimeLimitCode(time.Now(), data, setting.Service.ActiveCodeLives, prefix) {
-			emailAddress := &EmailAddress{UID: user.ID, Email: email}
-			if has, _ := db.GetEngine(ctx).Get(emailAddress); has {
-				return emailAddress
-			}
-		}
-	}
-	return nil
-}
-
 // SearchEmailOrderBy is used to sort the results from SearchEmails()
 type SearchEmailOrderBy string
 

models/user/user.go

@@ -7,7 +7,9 @@ package user
 
 import (
 	"context"
+	"crypto/subtle"
 	"encoding/hex"
+	"errors"
 	"fmt"
 	"net/mail"
 	"net/url"
@@ -318,15 +320,14 @@ func (u *User) OrganisationLink() string {
 	return setting.AppSubURL + "/org/" + url.PathEscape(u.Name)
 }
 
-// GenerateEmailActivateCode generates an activate code based on user information and given e-mail.
-func (u *User) GenerateEmailActivateCode(email string) string {
-	code := base.CreateTimeLimitCode(
-		fmt.Sprintf("%d%s%s%s%s", u.ID, email, u.LowerName, u.Passwd, u.Rands),
-		setting.Service.ActiveCodeLives, time.Now(), nil)
-
-	// Add tail hex username
-	code += hex.EncodeToString([]byte(u.LowerName))
-	return code
+// GenerateEmailAuthorizationCode generates an activation code based for the user for the specified purpose.
+// The standard expiry is ActiveCodeLives minutes.
+func (u *User) GenerateEmailAuthorizationCode(ctx context.Context, purpose auth.AuthorizationPurpose) (string, error) {
+	lookup, validator, err := auth.GenerateAuthToken(ctx, u.ID, timeutil.TimeStampNow().Add(int64(setting.Service.ActiveCodeLives)*60), purpose)
+	if err != nil {
+		return "", err
+	}
+	return lookup + ":" + validator, nil
 }
 
 // GetUserFollowers returns range of user's followers.
@@ -836,35 +837,50 @@ func countUsers(ctx context.Context, opts *CountUserFilter) int64 {
 	return count
 }
 
-// GetVerifyUser get user by verify code
-func GetVerifyUser(ctx context.Context, code string) (user *User) {
-	if len(code) <= base.TimeLimitCodeLength {
-		return nil
+// VerifyUserActiveCode verifies that the code is valid for the given purpose for this user.
+// If delete is specified, the token will be deleted.
+func VerifyUserAuthorizationToken(ctx context.Context, code string, purpose auth.AuthorizationPurpose, delete bool) (*User, error) {
+	lookupKey, validator, found := strings.Cut(code, ":")
+	if !found {
+		return nil, nil
 	}
 
-	// use tail hex username query user
-	hexStr := code[base.TimeLimitCodeLength:]
-	if b, err := hex.DecodeString(hexStr); err == nil {
-		if user, err = GetUserByName(ctx, string(b)); user != nil {
-			return user
+	authToken, err := auth.FindAuthToken(ctx, lookupKey, purpose)
+	if err != nil {
+		if errors.Is(err, util.ErrNotExist) {
+			return nil, nil
 		}
-		log.Error("user.getVerifyUser: %v", err)
+		return nil, err
 	}
 
-	return nil
-}
+	if authToken.IsExpired() {
+		return nil, auth.DeleteAuthToken(ctx, authToken)
+	}
+
+	rawValidator, err := hex.DecodeString(validator)
+	if err != nil {
+		return nil, err
+	}
+
+	if subtle.ConstantTimeCompare([]byte(authToken.HashedValidator), []byte(auth.HashValidator(rawValidator))) == 0 {
+		return nil, errors.New("validator doesn't match")
+	}
 
-// VerifyUserActiveCode verifies active code when active account
-func VerifyUserActiveCode(ctx context.Context, code string) (user *User) {
-	if user = GetVerifyUser(ctx, code); user != nil {
-		// time limit code
-		prefix := code[:base.TimeLimitCodeLength]
-		data := fmt.Sprintf("%d%s%s%s%s", user.ID, user.Email, user.LowerName, user.Passwd, user.Rands)
-		if base.VerifyTimeLimitCode(time.Now(), data, setting.Service.ActiveCodeLives, prefix) {
-			return user
+	u, err := GetUserByID(ctx, authToken.UID)
+	if err != nil {
+		if IsErrUserNotExist(err) {
+			return nil, nil
 		}
+		return nil, err
 	}
-	return nil
+
+	if delete {
+		if err := auth.DeleteAuthToken(ctx, authToken); err != nil {
+			return nil, err
+		}
+	}
+
+	return u, nil
 }
 
 // ValidateUser check if user is valid to insert / update into database

models/user/user_test.go

@@ -7,6 +7,7 @@ package user_test
 import (
 	"context"
 	"crypto/rand"
+	"encoding/hex"
 	"fmt"
 	"strings"
 	"testing"
@@ -21,7 +22,9 @@ import (
 	"code.gitea.io/gitea/modules/optional"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/structs"
+	"code.gitea.io/gitea/modules/test"
 	"code.gitea.io/gitea/modules/timeutil"
+	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/tests"
 
 	"github.com/stretchr/testify/assert"
@@ -699,3 +702,66 @@ func TestDisabledUserFeatures(t *testing.T) {
 		assert.True(t, user_model.IsFeatureDisabledWithLoginType(user, f))
 	}
 }
+
+func TestGenerateEmailAuthorizationCode(t *testing.T) {
+	defer test.MockVariableValue(&setting.Service.ActiveCodeLives, 2)()
+	require.NoError(t, unittest.PrepareTestDatabase())
+
+	user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
+
+	code, err := user.GenerateEmailAuthorizationCode(db.DefaultContext, auth.UserActivation)
+	require.NoError(t, err)
+
+	lookupKey, validator, ok := strings.Cut(code, ":")
+	assert.True(t, ok)
+
+	rawValidator, err := hex.DecodeString(validator)
+	require.NoError(t, err)
+
+	authToken, err := auth.FindAuthToken(db.DefaultContext, lookupKey, auth.UserActivation)
+	require.NoError(t, err)
+	assert.False(t, authToken.IsExpired())
+	assert.EqualValues(t, authToken.HashedValidator, auth.HashValidator(rawValidator))
+
+	authToken.Expiry = authToken.Expiry.Add(-int64(setting.Service.ActiveCodeLives) * 60)
+	assert.True(t, authToken.IsExpired())
+}
+
+func TestVerifyUserAuthorizationToken(t *testing.T) {
+	defer test.MockVariableValue(&setting.Service.ActiveCodeLives, 2)()
+	require.NoError(t, unittest.PrepareTestDatabase())
+
+	user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
+
+	code, err := user.GenerateEmailAuthorizationCode(db.DefaultContext, auth.UserActivation)
+	require.NoError(t, err)
+
+	lookupKey, _, ok := strings.Cut(code, ":")
+	assert.True(t, ok)
+
+	t.Run("Wrong purpose", func(t *testing.T) {
+		u, err := user_model.VerifyUserAuthorizationToken(db.DefaultContext, code, auth.PasswordReset, false)
+		require.NoError(t, err)
+		assert.Nil(t, u)
+	})
+
+	t.Run("No delete", func(t *testing.T) {
+		u, err := user_model.VerifyUserAuthorizationToken(db.DefaultContext, code, auth.UserActivation, false)
+		require.NoError(t, err)
+		assert.EqualValues(t, user.ID, u.ID)
+
+		authToken, err := auth.FindAuthToken(db.DefaultContext, lookupKey, auth.UserActivation)
+		require.NoError(t, err)
+		assert.NotNil(t, authToken)
+	})
+
+	t.Run("Delete", func(t *testing.T) {
+		u, err := user_model.VerifyUserAuthorizationToken(db.DefaultContext, code, auth.UserActivation, true)
+		require.NoError(t, err)
+		assert.EqualValues(t, user.ID, u.ID)
+
+		authToken, err := auth.FindAuthToken(db.DefaultContext, lookupKey, auth.UserActivation)
+		require.ErrorIs(t, err, util.ErrNotExist)
+		assert.Nil(t, authToken)
+	})
+}

modules/base/tool.go

@@ -4,26 +4,20 @@
 package base
 
 import (
-	"crypto/hmac"
-	"crypto/sha1"
 	"crypto/sha256"
-	"crypto/subtle"
 	"encoding/base64"
 	"encoding/hex"
 	"errors"
 	"fmt"
-	"hash"
 	"os"
 	"path/filepath"
 	"runtime"
 	"strconv"
 	"strings"
-	"time"
 	"unicode/utf8"
 
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/log"
-	"code.gitea.io/gitea/modules/setting"
 
 	"github.com/dustin/go-humanize"
 )
@@ -54,66 +48,6 @@ func BasicAuthDecode(encoded string) (string, string, error) {
 	return "", "", errors.New("invalid basic authentication")
 }
 
-// VerifyTimeLimitCode verify time limit code
-func VerifyTimeLimitCode(now time.Time, data string, minutes int, code string) bool {
-	if len(code) <= 18 {
-		return false
-	}
-
-	startTimeStr := code[:12]
-	aliveTimeStr := code[12:18]
-	aliveTime, _ := strconv.Atoi(aliveTimeStr) // no need to check err, if anything wrong, the following code check will fail soon
-
-	// check code
-	retCode := CreateTimeLimitCode(data, aliveTime, startTimeStr, nil)
-	if subtle.ConstantTimeCompare([]byte(retCode), []byte(code)) != 1 {
-		retCode = CreateTimeLimitCode(data, aliveTime, startTimeStr, sha1.New()) // TODO: this is only for the support of legacy codes, remove this in/after 1.23
-		if subtle.ConstantTimeCompare([]byte(retCode), []byte(code)) != 1 {
-			return false
-		}
-	}
-
-	// check time is expired or not: startTime <= now && now < startTime + minutes
-	startTime, _ := time.ParseInLocation("200601021504", startTimeStr, time.Local)
-	return (startTime.Before(now) || startTime.Equal(now)) && now.Before(startTime.Add(time.Minute*time.Duration(minutes)))
-}
-
-// TimeLimitCodeLength default value for time limit code
-const TimeLimitCodeLength = 12 + 6 + 40
-
-// CreateTimeLimitCode create a time-limited code.
-// Format: 12 length date time string + 6 minutes string (not used) + 40 hash string, some other code depends on this fixed length
-// If h is nil, then use the default hmac hash.
-func CreateTimeLimitCode[T time.Time | string](data string, minutes int, startTimeGeneric T, h hash.Hash) string {
-	const format = "200601021504"
-
-	var start time.Time
-	var startTimeAny any = startTimeGeneric
-	if t, ok := startTimeAny.(time.Time); ok {
-		start = t
-	} else {
-		var err error
-		start, err = time.ParseInLocation(format, startTimeAny.(string), time.Local)
-		if err != nil {
-			return "" // return an invalid code because the "parse" failed
-		}
-	}
-	startStr := start.Format(format)
-	end := start.Add(time.Minute * time.Duration(minutes))
-
-	if h == nil {
-		h = hmac.New(sha1.New, setting.GetGeneralTokenSigningSecret())
-	}
-	_, _ = fmt.Fprintf(h, "%s%s%s%s%d", data, hex.EncodeToString(setting.GetGeneralTokenSigningSecret()), startStr, end.Format(format), minutes)
-	encoded := hex.EncodeToString(h.Sum(nil))
-
-	code := fmt.Sprintf("%s%06d%s", startStr, minutes, encoded)
-	if len(code) != TimeLimitCodeLength {
-		panic("there is a hard requirement for the length of time-limited code") // it shouldn't happen
-	}
-	return code
-}
-
 // FileSize calculates the file size and generate user-friendly string.
 func FileSize(s int64) string {
 	return humanize.IBytes(uint64(s))