Enhanced auth token / remember me (#27606)

Closes #27455

> The mechanism responsible for long-term authentication (the 'remember
me' cookie) uses a weak construction technique. It will hash the user's
hashed password and the rands value; it will then call the secure cookie
code, which will encrypt the user's name with the computed hash. If one
were able to dump the database, they could extract those two values to
rebuild that cookie and impersonate a user. That vulnerability exists
from the date the dump was obtained until a user changed their password.
> 
> To fix this security issue, the cookie could be created and verified
using a different technique such as the one explained at
https://paragonie.com/blog/2015/04/secure-authentication-php-with-long-term-persistence#secure-remember-me-cookies.

The PR removes the now obsolete setting `COOKIE_USERNAME`.

1 files changed, 251 insertions, 0 deletions

diff --git a/models/auth/access_token.go b/models/auth/access_token.go
new file mode 100644
index 0000000000..8abcc622bc
--- /dev/null
+++ b/models/auth/access_token.go
@@ -0,0 +1,251 @@
+// Copyright 2014 The Gogs Authors. All rights reserved.
+// Copyright 2019 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package auth
+
+import (
+	"context"
+	"crypto/subtle"
+	"encoding/hex"
+	"fmt"
+	"time"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/timeutil"
+	"code.gitea.io/gitea/modules/util"
+
+	lru "github.com/hashicorp/golang-lru/v2"
+)
+
+// ErrAccessTokenNotExist represents a "AccessTokenNotExist" kind of error.
+type ErrAccessTokenNotExist struct {
+	Token string
+}
+
+// IsErrAccessTokenNotExist checks if an error is a ErrAccessTokenNotExist.
+func IsErrAccessTokenNotExist(err error) bool {
+	_, ok := err.(ErrAccessTokenNotExist)
+	return ok
+}
+
+func (err ErrAccessTokenNotExist) Error() string {
+	return fmt.Sprintf("access token does not exist [sha: %s]", err.Token)
+}
+
+func (err ErrAccessTokenNotExist) Unwrap() error {
+	return util.ErrNotExist
+}
+
+// ErrAccessTokenEmpty represents a "AccessTokenEmpty" kind of error.
+type ErrAccessTokenEmpty struct{}
+
+// IsErrAccessTokenEmpty checks if an error is a ErrAccessTokenEmpty.
+func IsErrAccessTokenEmpty(err error) bool {
+	_, ok := err.(ErrAccessTokenEmpty)
+	return ok
+}
+
+func (err ErrAccessTokenEmpty) Error() string {
+	return "access token is empty"
+}
+
+func (err ErrAccessTokenEmpty) Unwrap() error {
+	return util.ErrInvalidArgument
+}
+
+var successfulAccessTokenCache *lru.Cache[string, any]
+
+// AccessToken represents a personal access token.
+type AccessToken struct {
+	ID             int64 `xorm:"pk autoincr"`
+	UID            int64 `xorm:"INDEX"`
+	Name           string
+	Token          string `xorm:"-"`
+	TokenHash      string `xorm:"UNIQUE"` // sha256 of token
+	TokenSalt      string
+	TokenLastEight string `xorm:"INDEX token_last_eight"`
+	Scope          AccessTokenScope
+
+	CreatedUnix       timeutil.TimeStamp `xorm:"INDEX created"`
+	UpdatedUnix       timeutil.TimeStamp `xorm:"INDEX updated"`
+	HasRecentActivity bool               `xorm:"-"`
+	HasUsed           bool               `xorm:"-"`
+}
+
+// AfterLoad is invoked from XORM after setting the values of all fields of this object.
+func (t *AccessToken) AfterLoad() {
+	t.HasUsed = t.UpdatedUnix > t.CreatedUnix
+	t.HasRecentActivity = t.UpdatedUnix.AddDuration(7*24*time.Hour) > timeutil.TimeStampNow()
+}
+
+func init() {
+	db.RegisterModel(new(AccessToken), func() error {
+		if setting.SuccessfulTokensCacheSize > 0 {
+			var err error
+			successfulAccessTokenCache, err = lru.New[string, any](setting.SuccessfulTokensCacheSize)
+			if err != nil {
+				return fmt.Errorf("unable to allocate AccessToken cache: %w", err)
+			}
+		} else {
+			successfulAccessTokenCache = nil
+		}
+		return nil
+	})
+}
+
+// NewAccessToken creates new access token.
+func NewAccessToken(ctx context.Context, t *AccessToken) error {
+	salt, err := util.CryptoRandomString(10)
+	if err != nil {
+		return err
+	}
+	token, err := util.CryptoRandomBytes(20)
+	if err != nil {
+		return err
+	}
+	t.TokenSalt = salt
+	t.Token = hex.EncodeToString(token)
+	t.TokenHash = HashToken(t.Token, t.TokenSalt)
+	t.TokenLastEight = t.Token[len(t.Token)-8:]
+	_, err = db.GetEngine(ctx).Insert(t)
+	return err
+}
+
+// DisplayPublicOnly whether to display this as a public-only token.
+func (t *AccessToken) DisplayPublicOnly() bool {
+	publicOnly, err := t.Scope.PublicOnly()
+	if err != nil {
+		return false
+	}
+	return publicOnly
+}
+
+func getAccessTokenIDFromCache(token string) int64 {
+	if successfulAccessTokenCache == nil {
+		return 0
+	}
+	tInterface, ok := successfulAccessTokenCache.Get(token)
+	if !ok {
+		return 0
+	}
+	t, ok := tInterface.(int64)
+	if !ok {
+		return 0
+	}
+	return t
+}
+
+// GetAccessTokenBySHA returns access token by given token value
+func GetAccessTokenBySHA(ctx context.Context, token string) (*AccessToken, error) {
+	if token == "" {
+		return nil, ErrAccessTokenEmpty{}
+	}
+	// A token is defined as being SHA1 sum these are 40 hexadecimal bytes long
+	if len(token) != 40 {
+		return nil, ErrAccessTokenNotExist{token}
+	}
+	for _, x := range []byte(token) {
+		if x < '0' || (x > '9' && x < 'a') || x > 'f' {
+			return nil, ErrAccessTokenNotExist{token}
+		}
+	}
+
+	lastEight := token[len(token)-8:]
+
+	if id := getAccessTokenIDFromCache(token); id > 0 {
+		accessToken := &AccessToken{
+			TokenLastEight: lastEight,
+		}
+		// Re-get the token from the db in case it has been deleted in the intervening period
+		has, err := db.GetEngine(ctx).ID(id).Get(accessToken)
+		if err != nil {
+			return nil, err
+		}
+		if has {
+			return accessToken, nil
+		}
+		successfulAccessTokenCache.Remove(token)
+	}
+
+	var tokens []AccessToken
+	err := db.GetEngine(ctx).Table(&AccessToken{}).Where("token_last_eight = ?", lastEight).Find(&tokens)
+	if err != nil {
+		return nil, err
+	} else if len(tokens) == 0 {
+		return nil, ErrAccessTokenNotExist{token}
+	}
+
+	for _, t := range tokens {
+		tempHash := HashToken(token, t.TokenSalt)
+		if subtle.ConstantTimeCompare([]byte(t.TokenHash), []byte(tempHash)) == 1 {
+			if successfulAccessTokenCache != nil {
+				successfulAccessTokenCache.Add(token, t.ID)
+			}
+			return &t, nil
+		}
+	}
+	return nil, ErrAccessTokenNotExist{token}
+}
+
+// AccessTokenByNameExists checks if a token name has been used already by a user.
+func AccessTokenByNameExists(ctx context.Context, token *AccessToken) (bool, error) {
+	return db.GetEngine(ctx).Table("access_token").Where("name = ?", token.Name).And("uid = ?", token.UID).Exist()
+}
+
+// ListAccessTokensOptions contain filter options
+type ListAccessTokensOptions struct {
+	db.ListOptions
+	Name   string
+	UserID int64
+}
+
+// ListAccessTokens returns a list of access tokens belongs to given user.
+func ListAccessTokens(ctx context.Context, opts ListAccessTokensOptions) ([]*AccessToken, error) {
+	sess := db.GetEngine(ctx).Where("uid=?", opts.UserID)
+
+	if len(opts.Name) != 0 {
+		sess = sess.Where("name=?", opts.Name)
+	}
+
+	sess = sess.Desc("created_unix")
+
+	if opts.Page != 0 {
+		sess = db.SetSessionPagination(sess, &opts)
+
+		tokens := make([]*AccessToken, 0, opts.PageSize)
+		return tokens, sess.Find(&tokens)
+	}
+
+	tokens := make([]*AccessToken, 0, 5)
+	return tokens, sess.Find(&tokens)
+}
+
+// UpdateAccessToken updates information of access token.
+func UpdateAccessToken(ctx context.Context, t *AccessToken) error {
+	_, err := db.GetEngine(ctx).ID(t.ID).AllCols().Update(t)
+	return err
+}
+
+// CountAccessTokens count access tokens belongs to given user by options
+func CountAccessTokens(ctx context.Context, opts ListAccessTokensOptions) (int64, error) {
+	sess := db.GetEngine(ctx).Where("uid=?", opts.UserID)
+	if len(opts.Name) != 0 {
+		sess = sess.Where("name=?", opts.Name)
+	}
+	return sess.Count(&AccessToken{})
+}
+
+// DeleteAccessTokenByID deletes access token by given ID.
+func DeleteAccessTokenByID(ctx context.Context, id, userID int64) error {
+	cnt, err := db.GetEngine(ctx).ID(id).Delete(&AccessToken{
+		UID: userID,
+	})
+	if err != nil {
+		return err
+	} else if cnt != 1 {
+		return ErrAccessTokenNotExist{}
+	}
+	return nil
+}