Increase Salt randomness (#18179)

- The current implementation of `RandomString` doesn't give you a most-possible unique randomness. It gives you 6*`length` instead of the possible 8*`length` bits(or as `length`x bytes) randomness. This is because `RandomString` is being limited to a max value of 63, this in order to represent the random byte as a letter/digit.
- The recommendation of pbkdf2 is to use 64+ bit salt, which the `RandomString` doesn't give with a length of 10, instead of increasing 10 to a higher number, this patch adds a new function called `RandomBytes` which does give you the guarentee of 8*`length` randomness and thus corresponding of `length`x bytes randomness.
- Use hexadecimal to store the bytes value in the database, as mentioned, it doesn't play nice in order to convert it to a string. This will always be a length of 32(with `length` being 16).
- When we detect on `Authenticate`(source: db) that a user has the old format of salt, re-hash the password such that the user will have it's password hashed with increased salt.

Thanks to @zeripath for working out the rouge edges from my first commit 😄.

Co-authored-by: lafriks <lauris@nix.lv>
Co-authored-by: zeripath <art27@cantab.net>
This commit is contained in:
Gusted 2022-01-04 15:13:52 +00:00 committed by GitHub
parent 165346c15c
commit 623c93ff46
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6 changed files with 115 additions and 14 deletions

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@ -363,6 +363,8 @@ var migrations = []Migration{
NewMigration("Add Sorting to ProjectIssue table", addProjectIssueSorting),
// v204 -> v205
NewMigration("Add key is verified to ssh key", addSSHKeyIsVerified),
// v205 -> v206
NewMigration("Migrate to higher varchar on user struct", migrateUserPasswordSalt),
}
// GetCurrentDBVersion returns the current db version

39
models/migrations/v205.go Normal file
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@ -0,0 +1,39 @@
// Copyright 2022 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package migrations
import (
"xorm.io/xorm"
"xorm.io/xorm/schemas"
)
func migrateUserPasswordSalt(x *xorm.Engine) error {
dbType := x.Dialect().URI().DBType
// For SQLITE, the max length doesn't matter.
if dbType == schemas.SQLITE {
return nil
}
if err := modifyColumn(x, "user", &schemas.Column{
Name: "rands",
SQLType: schemas.SQLType{
Name: "VARCHAR",
},
Length: 32,
// MySQL will like us again.
Nullable: true,
}); err != nil {
return err
}
return modifyColumn(x, "user", &schemas.Column{
Name: "salt",
SQLType: schemas.SQLType{
Name: "VARCHAR",
},
Length: 32,
Nullable: true,
})
}

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@ -95,8 +95,8 @@ type User struct {
Type UserType
Location string
Website string
Rands string `xorm:"VARCHAR(10)"`
Salt string `xorm:"VARCHAR(10)"`
Rands string `xorm:"VARCHAR(32)"`
Salt string `xorm:"VARCHAR(32)"`
Language string `xorm:"VARCHAR(5)"`
Description string
@ -358,24 +358,40 @@ func (u *User) NewGitSig() *git.Signature {
}
}
func hashPassword(passwd, salt, algo string) string {
func hashPassword(passwd, salt, algo string) (string, error) {
var tempPasswd []byte
var saltBytes []byte
// There are two formats for the Salt value:
// * The new format is a (32+)-byte hex-encoded string
// * The old format was a 10-byte binary format
// We have to tolerate both here but Authenticate should
// regenerate the Salt following a successful validation.
if len(salt) == 10 {
saltBytes = []byte(salt)
} else {
var err error
saltBytes, err = hex.DecodeString(salt)
if err != nil {
return "", err
}
}
switch algo {
case algoBcrypt:
tempPasswd, _ = bcrypt.GenerateFromPassword([]byte(passwd), bcrypt.DefaultCost)
return string(tempPasswd)
return string(tempPasswd), nil
case algoScrypt:
tempPasswd, _ = scrypt.Key([]byte(passwd), []byte(salt), 65536, 16, 2, 50)
tempPasswd, _ = scrypt.Key([]byte(passwd), saltBytes, 65536, 16, 2, 50)
case algoArgon2:
tempPasswd = argon2.IDKey([]byte(passwd), []byte(salt), 2, 65536, 8, 50)
tempPasswd = argon2.IDKey([]byte(passwd), saltBytes, 2, 65536, 8, 50)
case algoPbkdf2:
fallthrough
default:
tempPasswd = pbkdf2.Key([]byte(passwd), []byte(salt), 10000, 50, sha256.New)
tempPasswd = pbkdf2.Key([]byte(passwd), saltBytes, 10000, 50, sha256.New)
}
return fmt.Sprintf("%x", tempPasswd)
return fmt.Sprintf("%x", tempPasswd), nil
}
// SetPassword hashes a password using the algorithm defined in the config value of PASSWORD_HASH_ALGO
@ -391,15 +407,20 @@ func (u *User) SetPassword(passwd string) (err error) {
if u.Salt, err = GetUserSalt(); err != nil {
return err
}
if u.Passwd, err = hashPassword(passwd, u.Salt, setting.PasswordHashAlgo); err != nil {
return err
}
u.PasswdHashAlgo = setting.PasswordHashAlgo
u.Passwd = hashPassword(passwd, u.Salt, setting.PasswordHashAlgo)
return nil
}
// ValidatePassword checks if given password matches the one belongs to the user.
func (u *User) ValidatePassword(passwd string) bool {
tempHash := hashPassword(passwd, u.Salt, u.PasswdHashAlgo)
tempHash, err := hashPassword(passwd, u.Salt, u.PasswdHashAlgo)
if err != nil {
return false
}
if u.PasswdHashAlgo != algoBcrypt && subtle.ConstantTimeCompare([]byte(u.Passwd), []byte(tempHash)) == 1 {
return true
@ -505,9 +526,19 @@ func IsUserExist(uid int64, name string) (bool, error) {
return isUserExist(db.GetEngine(db.DefaultContext), uid, name)
}
// Note: As of the beginning of 2022, it is recommended to use at least
// 64 bits of salt, but NIST is already recommending to use to 128 bits.
// (16 bytes = 16 * 8 = 128 bits)
const SaltByteLength = 16
// GetUserSalt returns a random user salt token.
func GetUserSalt() (string, error) {
return util.RandomString(10)
rBytes, err := util.RandomBytes(SaltByteLength)
if err != nil {
return "", err
}
// Returns a 32 bytes long string.
return hex.EncodeToString(rBytes), nil
}
// NewGhostUser creates and returns a fake user for someone has deleted his/her account.

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@ -139,11 +139,11 @@ func MergeInto(dict map[string]interface{}, values ...interface{}) (map[string]i
// RandomInt returns a random integer between 0 and limit, inclusive
func RandomInt(limit int64) (int64, error) {
int, err := rand.Int(rand.Reader, big.NewInt(limit))
rInt, err := rand.Int(rand.Reader, big.NewInt(limit))
if err != nil {
return 0, err
}
return int.Int64(), nil
return rInt.Int64(), nil
}
const letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
@ -161,3 +161,12 @@ func RandomString(length int64) (string, error) {
}
return string(bytes), nil
}
// RandomBytes generates `length` bytes
// This differs from RandomString, as RandomString is limits each byte to have
// a maximum value of 63 instead of 255(max byte size)
func RandomBytes(length int64) ([]byte, error) {
bytes := make([]byte, length)
_, err := rand.Read(bytes)
return bytes, err
}

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@ -157,6 +157,24 @@ func Test_RandomString(t *testing.T) {
assert.NotEqual(t, str3, str4)
}
func Test_RandomBytes(t *testing.T) {
bytes1, err := RandomBytes(32)
assert.NoError(t, err)
bytes2, err := RandomBytes(32)
assert.NoError(t, err)
assert.NotEqual(t, bytes1, bytes2)
bytes3, err := RandomBytes(256)
assert.NoError(t, err)
bytes4, err := RandomBytes(256)
assert.NoError(t, err)
assert.NotEqual(t, bytes3, bytes4)
}
func Test_OptionalBool(t *testing.T) {
assert.Equal(t, OptionalBoolNone, OptionalBoolParse(""))
assert.Equal(t, OptionalBoolNone, OptionalBoolParse("x"))

View file

@ -21,7 +21,9 @@ func Authenticate(user *user_model.User, login, password string) (*user_model.Us
}
// Update password hash if server password hash algorithm have changed
if user.PasswdHashAlgo != setting.PasswordHashAlgo {
// Or update the password when the salt length doesn't match the current
// recommended salt length, this in order to migrate user's salts to a more secure salt.
if user.PasswdHashAlgo != setting.PasswordHashAlgo || len(user.Salt) != user_model.SaltByteLength*2 {
if err := user.SetPassword(password); err != nil {
return nil, err
}