fraenky8 / tables-to-go

//

// Copyright 2018 The Go-MySQL-Driver Authors. All rights reserved.

//

// This Source Code Form is subject to the terms of the Mozilla Public

// License, v. 2.0. If a copy of the MPL was not distributed with this file,

// You can obtain one at http://mozilla.org/MPL/2.0/.

package mysql

import (

	"crypto/rand"

	"crypto/rsa"

	"crypto/sha1"

	"crypto/sha256"

	"crypto/x509"

	"encoding/pem"

	"sync"

)

// server pub keys registry

var (

	serverPubKeyLock     sync.RWMutex

	serverPubKeyRegistry map[string]*rsa.PublicKey

)

// RegisterServerPubKey registers a server RSA public key which can be used to

// send data in a secure manner to the server without receiving the public key

// in a potentially insecure way from the server first.

// Registered keys can afterwards be used adding serverPubKey=<name> to the DSN.

//

// Note: The provided rsa.PublicKey instance is exclusively owned by the driver

// after registering it and may not be modified.

//

//  data, err := ioutil.ReadFile("mykey.pem")

//  if err != nil {

//  	log.Fatal(err)

//  }

//

//  block, _ := pem.Decode(data)

//  if block == nil || block.Type != "PUBLIC KEY" {

//  	log.Fatal("failed to decode PEM block containing public key")

//  }

//

//  pub, err := x509.ParsePKIXPublicKey(block.Bytes)

//  if err != nil {

//  	log.Fatal(err)

//  }

//

//  if rsaPubKey, ok := pub.(*rsa.PublicKey); ok {

//  	mysql.RegisterServerPubKey("mykey", rsaPubKey)

//  } else {

//  	log.Fatal("not a RSA public key")

//  }

//

func RegisterServerPubKey(name string, pubKey *rsa.PublicKey) {

	serverPubKeyLock.Lock()

	if serverPubKeyRegistry == nil {

		serverPubKeyRegistry = make(map[string]*rsa.PublicKey)

	}

	serverPubKeyRegistry[name] = pubKey

	serverPubKeyLock.Unlock()

}

// DeregisterServerPubKey removes the public key registered with the given name.

func DeregisterServerPubKey(name string) {

	serverPubKeyLock.Lock()

	if serverPubKeyRegistry != nil {

		delete(serverPubKeyRegistry, name)

	}

	serverPubKeyLock.Unlock()

}

func getServerPubKey(name string) (pubKey *rsa.PublicKey) {

	serverPubKeyLock.RLock()

	if v, ok := serverPubKeyRegistry[name]; ok {

		pubKey = v

	}

	serverPubKeyLock.RUnlock()

	return

}

// Hash password using pre 4.1 (old password) method

// https://github.com/atcurtis/mariadb/blob/master/mysys/my_rnd.c

type myRnd struct {

	seed1, seed2 uint32

}

const myRndMaxVal = 0x3FFFFFFF

// Pseudo random number generator

func newMyRnd(seed1, seed2 uint32) *myRnd {

	return &myRnd{

		seed1: seed1 % myRndMaxVal,

		seed2: seed2 % myRndMaxVal,

	}

}

// Tested to be equivalent to MariaDB's floating point variant

// http://play.golang.org/p/QHvhd4qved

// http://play.golang.org/p/RG0q4ElWDx

// Generate binary hash from byte string using insecure pre 4.1 method

func pwHash(password []byte) (result [2]uint32) {

	var add uint32 = 7

	var tmp uint32

	result[0] = 1345345333

	result[1] = 0x12345671

	for _, c := range password {

		// skip spaces and tabs in password

		if c == ' ' || c == '\t' {

			continue

		}

		tmp = uint32(c)

		result[0] ^= (((result[0] & 63) + add) * tmp) + (result[0] << 8)

		result[1] += (result[1] << 8) ^ result[0]

		add += tmp

	}

	// Remove sign bit (1<<31)-1)

	result[0] &= 0x7FFFFFFF

	result[1] &= 0x7FFFFFFF

	return

}

// Hash password using insecure pre 4.1 method

func scrambleOldPassword(scramble []byte, password string) []byte {

	if len(password) == 0 {

		return nil

	}

	scramble = scramble[:8]

	hashPw := pwHash([]byte(password))

	hashSc := pwHash(scramble)

	r := newMyRnd(hashPw[0]^hashSc[0], hashPw[1]^hashSc[1])

	var out [8]byte

	for i := range out {

		out[i] = r.NextByte() + 64

	}

	mask := r.NextByte()

	for i := range out {

		out[i] ^= mask

	}

	return out[:]

}

// Hash password using 4.1+ method (SHA1)

func scramblePassword(scramble []byte, password string) []byte {

	if len(password) == 0 {

		return nil

	}

	// stage1Hash = SHA1(password)

	crypt := sha1.New()

	crypt.Write([]byte(password))

	stage1 := crypt.Sum(nil)

	// scrambleHash = SHA1(scramble + SHA1(stage1Hash))

	// inner Hash

	crypt.Reset()

	crypt.Write(stage1)

	hash := crypt.Sum(nil)

	// outer Hash

	crypt.Reset()

	crypt.Write(scramble)

	crypt.Write(hash)

	scramble = crypt.Sum(nil)

	// token = scrambleHash XOR stage1Hash

	for i := range scramble {

		scramble[i] ^= stage1[i]

	}

	return scramble

}

// Hash password using MySQL 8+ method (SHA256)

func scrambleSHA256Password(scramble []byte, password string) []byte {

	if len(password) == 0 {

		return nil

	}

	// XOR(SHA256(password), SHA256(SHA256(SHA256(password)), scramble))

	crypt := sha256.New()

	crypt.Write([]byte(password))

	message1 := crypt.Sum(nil)

	crypt.Reset()

	crypt.Write(message1)

	message1Hash := crypt.Sum(nil)

	crypt.Reset()

	crypt.Write(message1Hash)

	crypt.Write(scramble)

	message2 := crypt.Sum(nil)

	for i := range message1 {

		message1[i] ^= message2[i]

	}

	return message1

}

func encryptPassword(password string, seed []byte, pub *rsa.PublicKey) ([]byte, error) {

	plain := make([]byte, len(password)+1)

	copy(plain, password)

	for i := range plain {

		j := i % len(seed)

		plain[i] ^= seed[j]

	}

	sha1 := sha1.New()

	return rsa.EncryptOAEP(sha1, rand.Reader, pub, plain, nil)

}

func (mc *mysqlConn) sendEncryptedPassword(seed []byte, pub *rsa.PublicKey) error {

	enc, err := encryptPassword(mc.cfg.Passwd, seed, pub)

	if err != nil {

		return err

	}

	return mc.writeAuthSwitchPacket(enc)

}

func (mc *mysqlConn) auth(authData []byte, plugin string) ([]byte, error) {

	switch plugin {

	case "caching_sha2_password":

		authResp := scrambleSHA256Password(authData, mc.cfg.Passwd)

		return authResp, nil

	case "mysql_old_password":

		if !mc.cfg.AllowOldPasswords {

			return nil, ErrOldPassword

		}

		// Note: there are edge cases where this should work but doesn't;

		// this is currently "wontfix":

		// https://github.com/go-sql-driver/mysql/issues/184

		authResp := append(scrambleOldPassword(authData[:8], mc.cfg.Passwd), 0)

		return authResp, nil

	case "mysql_clear_password":

		if !mc.cfg.AllowCleartextPasswords {

			return nil, ErrCleartextPassword

		}

		// http://dev.mysql.com/doc/refman/5.7/en/cleartext-authentication-plugin.html

		// http://dev.mysql.com/doc/refman/5.7/en/pam-authentication-plugin.html

		return append([]byte(mc.cfg.Passwd), 0), nil

	case "mysql_native_password":

		if !mc.cfg.AllowNativePasswords {

			return nil, ErrNativePassword

		}

		// https://dev.mysql.com/doc/internals/en/secure-password-authentication.html

		// Native password authentication only need and will need 20-byte challenge.

		authResp := scramblePassword(authData[:20], mc.cfg.Passwd)

		return authResp, nil

	case "sha256_password":

		if len(mc.cfg.Passwd) == 0 {

			return []byte{0}, nil

		}

		if mc.cfg.tls != nil || mc.cfg.Net == "unix" {

			// write cleartext auth packet

			return append([]byte(mc.cfg.Passwd), 0), nil

		}

		pubKey := mc.cfg.pubKey

		if pubKey == nil {

			// request public key from server

			return []byte{1}, nil

		}

		// encrypted password

		enc, err := encryptPassword(mc.cfg.Passwd, authData, pubKey)

		return enc, err

	default:

		errLog.Print("unknown auth plugin:", plugin)

		return nil, ErrUnknownPlugin

	}

}

func (mc *mysqlConn) handleAuthResult(oldAuthData []byte, plugin string) error {

	// Read Result Packet

	authData, newPlugin, err := mc.readAuthResult()

	if err != nil {

		return err

	}

	// handle auth plugin switch, if requested

	if newPlugin != "" {

		// If CLIENT_PLUGIN_AUTH capability is not supported, no new cipher is

		// sent and we have to keep using the cipher sent in the init packet.

		if authData == nil {

			authData = oldAuthData

		} else {

			// copy data from read buffer to owned slice

			copy(oldAuthData, authData)

		}

		plugin = newPlugin

		authResp, err := mc.auth(authData, plugin)

		if err != nil {

			return err

		}

		if err = mc.writeAuthSwitchPacket(authResp); err != nil {

			return err

		}

		// Read Result Packet

		authData, newPlugin, err = mc.readAuthResult()

		if err != nil {

			return err

		}

		// Do not allow to change the auth plugin more than once

		if newPlugin != "" {

			return ErrMalformPkt

		}

	}

	switch plugin {

	// https://insidemysql.com/preparing-your-community-connector-for-mysql-8-part-2-sha256/

	case "caching_sha2_password":

		switch len(authData) {

		case 0:

			return nil // auth successful

		case 1:

			switch authData[0] {

			case cachingSha2PasswordFastAuthSuccess:

				if err = mc.readResultOK(); err == nil {

					return nil // auth successful

				}

			case cachingSha2PasswordPerformFullAuthentication:

				if mc.cfg.tls != nil || mc.cfg.Net == "unix" {

					// write cleartext auth packet

					err = mc.writeAuthSwitchPacket(append([]byte(mc.cfg.Passwd), 0))

					if err != nil {

						return err

					}

				} else {

					pubKey := mc.cfg.pubKey

					if pubKey == nil {

						// request public key from server

						data := mc.buf.takeSmallBuffer(4 + 1)

						data[4] = cachingSha2PasswordRequestPublicKey

						mc.writePacket(data)

						// parse public key

						data, err := mc.readPacket()

						if err != nil {

							return err

						}

						block, _ := pem.Decode(data[1:])

						pkix, err := x509.ParsePKIXPublicKey(block.Bytes)

						if err != nil {

							return err

						}

						pubKey = pkix.(*rsa.PublicKey)

					}

					// send encrypted password

					err = mc.sendEncryptedPassword(oldAuthData, pubKey)

					if err != nil {

						return err

					}

				}

				return mc.readResultOK()

			default:

				return ErrMalformPkt

			}

		default:

			return ErrMalformPkt

		}

	case "sha256_password":

		switch len(authData) {

		case 0:

			return nil // auth successful

		default:

			block, _ := pem.Decode(authData)

			pub, err := x509.ParsePKIXPublicKey(block.Bytes)

			if err != nil {

				return err

			}

			// send encrypted password

			err = mc.sendEncryptedPassword(oldAuthData, pub.(*rsa.PublicKey))

			if err != nil {

				return err

			}

			return mc.readResultOK()

		}

	default:

		return nil // auth successful

	}

	return err

}