/* Copyright (c) 2000, 2024, Oracle and/or its affiliates.

Copyright (c) 2023, 2025, GreatDB Software Co., Ltd.

This program is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License, version 2.0,

as published by the Free Software Foundation.

This program is designed to work with certain software (including

but not limited to OpenSSL) that is licensed under separate terms,

as designated in a particular file or component or in included license

documentation. The authors of MySQL hereby grant you an additional

permission to link the program and your derivative works with the

separately licensed software that they have either included with

the program or referenced in the documentation.

This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

GNU General Public License, version 2.0, for more details.

You should have received a copy of the GNU General Public License

along with this program; if not, write to the Free Software

Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */

#define LOG_COMPONENT_TAG "sha256_password"

#include "sql/auth/sql_authentication.h"

#include <fcntl.h>

#include <mysql/components/my_service.h>

#include <sql/ssl_acceptor_context_operator.h>

#include <sql/ssl_init_callback.h>

#include <stdio.h>

#include <string.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <string> /* std::string */

#include <utility>

#include <vector> /* std::vector */

#include "boost/algorithm/string.hpp"

#include "crypt_genhash_impl.h" // generate_user_salt

#include "include/compression.h"

#include "m_string.h"

#include "map_helpers.h"

#include "mutex_lock.h" // Mutex_lock

#include "my_byteorder.h"

#include "my_command.h"

#include "my_compiler.h"

#include "my_dbug.h"

#include "my_dir.h"

#include "my_inttypes.h"

#include "my_io.h"

#include "my_psi_config.h"

#include "my_rnd.h"

#include "my_sys.h"

#include "my_time.h"

#include "mysql/components/services/bits/psi_bits.h"

#include "mysql/components/services/log_builtins.h"

#include "mysql/components/services/log_shared.h"

#include "mysql/my_loglevel.h"

#include "mysql/plugin.h"

#include "mysql/psi/mysql_mutex.h"

#include "mysql/service_my_plugin_log.h"

#include "mysql/service_mysql_alloc.h"

#include "mysql/service_mysql_password_policy.h"

#include "mysql/strings/m_ctype.h"

#include "mysql_time.h"

#include "mysqld_error.h"

#include "password.h" // my_make_scrambled_password

#include "pfs_thread_provider.h"

#include "prealloced_array.h"

#include "sql/auth/auth_acls.h"

#include "sql/auth/auth_common.h"

#include "sql/auth/auth_internal.h" // optimize_plugin_compare_by_pointer

#include "sql/auth/partial_revokes.h"

#include "sql/auth/sql_auth_cache.h" // acl_cache

#include "sql/auth/sql_security_ctx.h"

#include "sql/conn_handler/connection_handler_manager.h" // Connection_handler_manager

#include "sql/current_thd.h" // current_thd

#include "sql/debug_sync.h" // DEBUG_SYNC

#include "sql/derror.h" // ER_THD

#include "sql/hostname_cache.h" // Host_errors, inc_host_errors

#include "sql/log.h" // query_logger

#include "sql/mysqld.h" // global_system_variables

#include "sql/protocol.h"

#include "sql/protocol_classic.h"

#include "sql/psi_memory_key.h" // key_memory_MPVIO_EXT_auth_info

#include "sql/sql_class.h" // THD

#include "sql/sql_connect.h" // thd_init_client_charset

#include "sql/sql_const.h"

#include "sql/sql_db.h" // mysql_change_db

#include "sql/sql_error.h"

#include "sql/sql_lex.h"

#include "sql/sql_plugin.h" // my_plugin_lock_by_name

#include "sql/sql_time.h" // Interval

#include "sql/strfunc.h"

#include "sql/system_variables.h"

#include "sql/tztime.h" // Time_zone

#include "sql_common.h" // mpvio_info

#include "sql_string.h"

#include "string_with_len.h"

#include "strmake.h"

#include "template_utils.h"

#include "violite.h"

struct MEM_ROOT;

#include <openssl/err.h>

#include <openssl/pem.h>

#include <openssl/rsa.h>

#include <openssl/x509v3.h>

constexpr const std::array rsa_key_sizes{2048, 2048, 2048, 3072, 7680, 15360};

/**

@file sql_authentication.cc

AUTHENTICATION CODE

including initial connect handshake, invoking appropriate plugins,

client-server plugin negotiation, COM_CHANGE_USER, and native

MySQL authentication plugins.

*/

/* clang-format off */

/**

@page page_protocol_connection_phase Connection Phase

The Connection Phase performs these tasks:

- exchange the capabilities of client and server

- setup SSL communication channel if requested

- authenticate the client against the server

It starts with the client connect()ing to the server which may send a

ERR packet and finish the handshake or send a Initial Handshake Packet

which the client answers with a Handshake Response Packet. At this stage

client can request SSL connection, in which case an SSL communication

channel is established before client sends its authentication response.

@note In case the server sent a ERR packet as first packet it will happen

before the client and server negotiated any capabilities.

Therefore the ERR packet will not contain the SQL-state.

After initial handshake, server informs client about the method to be used

for authentication (unless it was already established during the handshake)

and the authentication exchange continues until server either accepts

connection by sending an @ref page_protocol_basic_ok_packet or rejects it

with @ref page_protocol_basic_err_packet.

@startuml

(*) --> "Initial Handshake Packet"

"Initial Handshake Packet" --> "Client Response"

"Initial Handshake Packet" --> "SSL Exchange"

"SSL Exchange" --> "Client Response"

"Client Response" --> "Authentication method switch"

"Client Response" --> "Authentication exchange continuation"

"Client Response" --> [ Insufficient client capabilities] ERR

"Authentication method switch" --> [ Client does not know requested auth method ] DISCONNECT

"Authentication method switch" --> "Authentication exchange continuation"

"Authentication exchange continuation" --> "Server Response"

"Authentication exchange continuation" --> [ No more factors to authenticate] OK

"Authentication exchange continuation" --> ERR

"Server Response" --> "Authenticate 2nd Factor"

"Server Response" --> "Authenticate 3rd Factor"

"Authenticate 2nd Factor" --> "MFA Authentication Client Response"

"Authenticate 3rd Factor" --> "MFA Authentication Client Response"

"MFA Authentication Client Response" --> "Authentication exchange continuation"

"MFA Authentication Client Response" --> [ Client does not know requested auth method ] DISCONNECT

@enduml

@section sect_protocol_connection_phase_initial_handshake Initial Handshake

The initial handshake starts with the server sending the

@ref page_protocol_connection_phase_packets_protocol_handshake packet.

After this, optionally, the client can request an SSL connection to be

established with the @ref page_protocol_connection_phase_packets_protocol_ssl_request

packet and then the client sends the

@ref page_protocol_connection_phase_packets_protocol_handshake_response packet.

@subsection sect_protocol_connection_phase_initial_handshake_plain_handshake Plain Handshake

1. Server sending @ref page_protocol_connection_phase_packets_protocol_handshake.

2. Client replying with @ref page_protocol_connection_phase_packets_protocol_handshake_response

@startuml

Server -> Client: Initial Handshake Packet

Client -> Server: Handshake Response Packet

Server -> Server: Check client capabilities and authentication method to use

@enduml

@subsection sect_protocol_connection_phase_initial_handshake_ssl_handshake SSL Handshake

1. Server sending @ref page_protocol_connection_phase_packets_protocol_handshake

2. Client replying with @ref page_protocol_connection_phase_packets_protocol_ssl_request

3. The usual SSL exchange leading to establishing SSL connection

4. Client sends @ref page_protocol_connection_phase_packets_protocol_handshake_response

@startuml

Server -> Client: Initial Handshake Packet

Client -> Server: SSL Connection Request Packet

== SSL Exchange ==

Client -> Server: Handshake Response Packet

Server -> Server: Check client capabilities and authentication method to use

@enduml

@subsection sect_protocol_connection_phase_initial_handshake_capabilities Capability Negotiation

To permit an old client to connect to newer servers,

the @ref page_protocol_connection_phase_packets_protocol_handshake contains

* the MySQL Server version

* the server's @ref group_cs_capabilities_flags

The client should only announce the capabilities in the

@ref page_protocol_connection_phase_packets_protocol_handshake_response

that it has in common with the server.

They can agree on:

* use of @ref CLIENT_TRANSACTIONS "status flags"

* use of @ref CLIENT_PROTOCOL_41 "SQL states for error codes"

* @ref sect_protocol_connection_phase_initial_handshake_auth_method "authentication methods"

* @ref CLIENT_SSL "SSL Support"

* @ref CLIENT_COMPRESS "Compression"

@subsection sect_protocol_connection_phase_initial_handshake_auth_method Determining Authentication Method

Method used for authentication is tied to the user account and stored in

the plugin column of mysql.user table. Client informs about the user

account it wants to log into in the

@ref page_protocol_connection_phase_packets_protocol_handshake_response packet.

Only then server can look up the mysql.user table and find the authentication

method to be used.

However, to save round-trips, server and client start authentication exchange

already in the initial handshake using an optimistic guess of the

authentication method to be used.

Server uses its default authentication method defined by @ref authentication_policy

to produce initial authentication data payload and sends it to the client inside

@ref page_protocol_connection_phase_packets_protocol_handshake, together with

the name of the method used.

Client can include in the

@ref page_protocol_connection_phase_packets_protocol_handshake_response packet

its reply to the authentication data sent by the server.

When including authentication reply in the

@ref page_protocol_connection_phase_packets_protocol_handshake_response,

client is not obligated to use the same authentication method that was used

by the server in the

@ref page_protocol_connection_phase_packets_protocol_handshake packet.

The name of the authentication method used by the client is stored in the

packet. If the guessed authentication method used either by the client or

the server in the initial handshake was not correct, server informs client

which authentication method should be used using

@ref page_protocol_connection_phase_packets_protocol_auth_switch_request.

See section @ref sect_protocol_connection_phase_auth_method_mismatch for

more details.

Up to MySQL 4.0 the MySQL protocol only supported the

@ref page_protocol_connection_phase_authentication_methods_old_password_authentication.

In MySQL 4.1 the

@ref page_protocol_connection_phase_authentication_methods_native_password_authentication

method was added and in MySQL 5.5 arbitrtary authentication methods can be implemented

by means of authentication plugins.

If the client or server do no support pluggable authentication

(i.e. @ref CLIENT_PLUGIN_AUTH capability flag is not set) then

authentication method used is inherited from client and server

capabilities as follows:

* The method used is

@ref page_protocol_connection_phase_authentication_methods_old_password_authentication

if @ref CLIENT_PROTOCOL_41 or @ref CLIENT_RESERVED2 "CLIENT_SECURE_CONNECTION"

are not set.

* The method used is

@ref page_protocol_connection_phase_authentication_methods_native_password_authentication

if both @ref CLIENT_PROTOCOL_41 and @ref CLIENT_RESERVED2 "CLIENT_SECURE_CONNECTION"

are set, but @ref CLIENT_PLUGIN_AUTH is not set.

@section sect_protocol_connection_phase_fast_path Authentication Phase Fast Path

Assume the client wants to log in via user account U and that user account

is defined to use authentication method `server_method`. The fast

authentication path is used when:

<ul>

<li>the server used `server_method` to generate authentication data in the

@ref page_protocol_connection_phase_packets_protocol_handshake packet.</li>

<li>the client used a `client_authentication_method` in

@ref page_protocol_connection_phase_packets_protocol_handshake_response

that is compatible with the `server_method` used by the server.</li>

</ul>

In that case the first round of authentication has been already commenced

during the handshake. Now, depending on the authentication method

`server_method`, further authentication can be exchanged until the server

either accepts or refuses the authentication.

@subsection sect_protocol_connection_phase_fast_path_success Successful Authentication

A successful fast authentication path looks as follows:

1. The client connects to the server

2. The server sends @ref page_protocol_connection_phase_packets_protocol_handshake

3. The client responds with

@ref page_protocol_connection_phase_packets_protocol_handshake_response

4. Client and server possibly exchange further packets as required by the server

authentication method for the user account the client is trying to authenticate

against.

5. The server responds with an @ref page_protocol_basic_ok_packet

@startuml

Client -> Server: Connect

Server -> Client: Initial Handshake Packet

Client -> Server: Handshake Response Packet

== Client and server possibly exchange further authentication method packets ==

Server -> Client: OK packet

== Client and server enter Command Phase ==

@enduml

The packets the server sends in step 4 are a

@ref page_protocol_connection_phase_packets_protocol_auth_more_data packet

prefixed with 0x01 to distinguish them from @ref page_protocol_basic_err_packet

and @ref page_protocol_basic_ok_packet

@note Many authentication methods, including the mysql_native_password method

consist of a single challenge-response exchange. In that case no extra packet are

exchanged in step 4 and the server sends an @ref page_protocol_basic_ok_packet

directly after receiving the

@ref page_protocol_connection_phase_packets_protocol_handshake_response

packet (provided the authentication was successful).

@subsection sect_protocol_connection_phase_fast_path_fails Authentication Fails

It goes exactly like @ref sect_protocol_connection_phase_fast_path_success,

but if the server decides that it won't authenticate the user, it replies

with an @ref page_protocol_basic_err_packet instead of

@ref page_protocol_basic_ok_packet.

1. The client connects to the server

2. The server sends @ref page_protocol_connection_phase_packets_protocol_handshake

3. The client responds with

@ref page_protocol_connection_phase_packets_protocol_handshake_response

4. Client and server possibly exchange further packets as required by the server

authentication method for the user account the client is trying to authenticate

against.

5. The server responds with an @ref page_protocol_basic_err_packet

@startuml

Client -> Server: Connect

Server -> Client: Initial Handshake Packet

Client -> Server: Handshake Response Packet

== Client and server possibly exchange further authentication method packets ==

Server -> Client: ERR packet

== Client and server close connection ==

@enduml

Again, the @ref page_protocol_connection_phase_packets_protocol_auth_more_data

packets sent by the server during step 4 start with 0x01 byte and thus can

never be confused with the @ref page_protocol_basic_err_packet.

@section sect_protocol_connection_phase_auth_method_mismatch Authentication Method Mismatch

Assume that client wants to log in as user U and that user account uses

authentication method M. If:

1. Server's default method used to generate authentication payload for

@ref page_protocol_connection_phase_packets_protocol_handshake was different

from M or

2. Method used by the client to generate authentication reply in

@ref page_protocol_connection_phase_packets_protocol_handshake_response

was not compatible with M

then there is an authentication method mismatch and authentication exchange

must be restarted using the correct authentication method.

@note

1. The mismatch can happen even if client and server used compatible

authentication methods in the initial handshake, but the method the server

used was different from the method required by the user account.

2. In the 4.1-5.7 server and client the default authentication method is

@ref page_protocol_connection_phase_authentication_methods_native_password_authentication.

3. In 8.0 server and client the default authentication method is

@ref page_caching_sha2_authentication_exchanges.

4. The client and the server can change their default authentication method via the

`--default-auth` option.

5. A sensibe thing to do for a client would be to see the server's default

authentication method announced in the

@ref page_protocol_connection_phase_packets_protocol_handshake packet and infer the

authentication method from it instead of using the client default authentication

method when producing

@ref page_protocol_connection_phase_packets_protocol_handshake_response.

But since there can be one to many server to client plugins and the clients

generally do not know the mapping from server authentication methods to client

authentication methods this is not implemented in the client mysql library.

If authentication method mismatch happens, server sends to client the

@ref page_protocol_connection_phase_packets_protocol_auth_switch_request

which contains the name of the client authentication method to be used and

the first authentication payload generated by the new method. Client should

switch to the requested authentication method and continue the exchange as

dictated by that method.

If the client does not know the requested method it should disconnect.

@subsection sect_protocol_connection_phase_auth_method_mismatch_method_change Authentication Method Change

1. The client connects to the server

2. The server sends @ref page_protocol_connection_phase_packets_protocol_handshake

3. The client responds with

@ref page_protocol_connection_phase_packets_protocol_handshake_response

4. The server sends the

@ref page_protocol_connection_phase_packets_protocol_auth_switch_request to tell

the client that it needs to switch to a new authentication method.

5. Client and server possibly exchange further packets as required by the server

authentication method for the user account the client is trying to authenticate

against.

6. The server responds with an @ref page_protocol_basic_ok_packet or rejects

with @ref page_protocol_basic_err_packet

@startuml

Client -> Server: Connect

Server -> Client: Initial Handshake Packet

Client -> Server: Handshake Response Packet

Server -> Client: Authentication Switch Request Packet

== Client and server possibly exchange further authentication method packets ==

Server -> Client: ERR packet or OK packet

@enduml

@subsection sect_protocol_connection_phase_auth_method_mismatch_insuficcient_client Insufficient Client Capabilities

Server will reject with @ref page_protocol_basic_err_packet if it discovers

that client capabilities are not sufficient to complete authentication.

This can happen in the following situations:

<ul>

<li>A client which does not support pluggable authentication

(@ref CLIENT_PLUGIN_AUTH flag not set) connects to an account which uses

authentication method different from

@ref page_protocol_connection_phase_authentication_methods_native_password_authentication

</li>

<li>

A client which does not support secure authentication (

@ref CLIENT_RESERVED2 "CLIENT_SECURE_CONNECTION" flag not set) attempts

to connect.

</li>

<li>Server's default authentication method used to generate authentication

data in @ref page_protocol_connection_phase_packets_protocol_handshake is

incompatible with

@ref page_protocol_connection_phase_authentication_methods_native_password_authentication

and client does not support pluggable authentication (@ref CLIENT_PLUGIN_AUTH

flag is not set).

</li>

</ul>

In either of these cases authentication phase will look as follows:

1. The client connects to the server

2. The server sends @ref page_protocol_connection_phase_packets_protocol_handshake

3. The client response with

@ref page_protocol_connection_phase_packets_protocol_handshake_response

4. The server recognizes that the client does not have enough capabilities

to handle the required authentication method, sends

@ref page_protocol_basic_err_packet and closes the connection.

@startuml

Client -> Server: Connect

Server -> Client: Initial Handshake Packet

Client -> Server: Handshake Response Packet

Server -> Client: Error Packet

== server disconnects ==

@enduml

@subsection sect_protocol_connection_phase_auth_method_mismatch_unknown_auth_method New Authentication Method Not Known by Client

Even if client supports external authentication (@ref CLIENT_PLUGIN_AUTH flag

is set) the new authentication method indicated in

@ref page_protocol_connection_phase_packets_protocol_auth_switch_request might

not be known to it. In that case the client simply disconnects.

1. The client connects to the server

2. The server sends @ref page_protocol_connection_phase_packets_protocol_handshake

3. The client response with

@ref page_protocol_connection_phase_packets_protocol_handshake_response

4. The server sends the

@ref page_protocol_connection_phase_packets_protocol_auth_switch_request to tell

the client that it needs to switch to a new authentication method.

5. client discovers that it does not know the authentication method requested by

the server - it disconnects.

@startuml

Client -> Server: Connect

Server -> Client: Initial Handshake Packet

Client -> Server: Handshake Response Packet

Server -> Client: Authentication Switch Packet

== client disconnects ==

@enduml

@subsection sect_protocol_connection_phase_auth_method_mismatch_non_client_plugin_auth Non-CLIENT_PLUGIN_AUTH Clients

@note This can only happen on pre-8.0 servers. 8.0 has the

@ref page_protocol_connection_phase_authentication_methods_old_password_authentication

removed.

The only situation where server will request authentication method change from

a client which does not set @ref CLIENT_PLUGIN_AUTH flag is when the following

conditions hold:

1. The client uses

@ref page_protocol_connection_phase_authentication_methods_old_password_authentication

for the @ref page_protocol_connection_phase_packets_protocol_handshake_response

packet.

2. The client supports secure authentication

(@ref CLIENT_RESERVED2 "CLIENT_SECURE_CONNECTION" is set)

3. Server's default authentication method is

@ref page_protocol_connection_phase_authentication_methods_native_password_authentication

In this case server sends

@ref page_protocol_connection_phase_packets_protocol_old_auth_switch_request.

This packet does not contain a new authenticartion method name because it's

implicitly assumed to be

@ref page_protocol_connection_phase_authentication_methods_native_password_authentication

and it does not contain authentication data.

Client replies with @ref sect_protocol_connection_phase_packets_protocol_handshake_response320.

To generate a password hash the client should re-use the random bytes sent by

the server in the

@ref page_protocol_connection_phase_packets_protocol_handshake.

@startuml

Client -> Server: Connect

Server -> Client: Initial Handshake Packet

Client -> Server: Handshake Response Packet

Server -> Client: Old Switch Request Packet

Client -> Server: Old Handshake Response

Server -> Client: ERR packet or OK packet

@enduml

@section sect_protocol_connection_phase_com_change_user_auth Authentication After COM_CHANGE_USER Command

During @ref page_protocol_command_phase a client can send a ::COM_CHANGE_USER

command which will trigger authenticating into a new account via a full

authentication handshake.

Similarly to the @ref page_protocol_connection_phase the server may reply

with a @ref page_protocol_basic_err_packet or

@ref page_protocol_basic_ok_packet for the usual fast-path or with

@ref page_protocol_connection_phase_packets_protocol_auth_switch_request

containing the authentication method to be used for the new account

and the first authentication data payload to be consumed by the client.

Further handshake continues as usual, as defined by the authentication

method of the new account. Eventually the server will accept the new

account with @ref page_protocol_basic_ok_packet or it will reject the change

with an @ref page_protocol_basic_err_packet and disconnect.

1. The client sends ::COM_CHANGE_USER packet

2. The server responds with the

@ref page_protocol_connection_phase_packets_protocol_auth_switch_request

which initiates authentication handshake using the correct authentication

method

3. Client and server exchange further packets as required by the

authentication method for the new account

4. The server responds with @ref page_protocol_basic_ok_packet and returns

to command phase or @ref page_protocol_basic_err_packet and closes

the connection.

@startuml

Client -> Server: COM_CHANGE_USER

Server -> Client: Auth Switch Request Packet

== packets exchanged depending on the authentication method ==

Server -> Client: ERR packet or OK packet

@enduml

@subsection sect_protocol_connection_phase_com_change_user_auth_non_plugin COM_CHANGE_USER and Non-CLIENT_PLUGIN_AUTH Clients

Clients which do not support pluggable authentication can send

::COM_CHANGE_USER command for accounts which use

@ref page_protocol_connection_phase_authentication_methods_native_password_authentication

or

@ref page_protocol_connection_phase_authentication_methods_old_password_authentication.

In this case it is assumed that server has already sent the authentication

challenge - the same which was sent when the client connected for the first

time - and client's reply to that challenge, i.e. the hash of the new

password, should be sent in the `auth_response` field of ::COM_CHANGE_USER.

1. The client sends ::COM_CHANGE_USER packet with authentication response

(hash of the password) for

@ref page_protocol_connection_phase_authentication_methods_native_password_authentication

(post 4.1 clients) or

@ref page_protocol_connection_phase_authentication_methods_old_password_authentication

(pre 4.1 clients) method.

2. The server responds with an @ref page_protocol_basic_ok_packet and returns

to @ref page_protocol_command_phase or with an

@ref page_protocol_basic_err_packet and closes the connection.

@startuml

Client -> Server : COM_CHANGE_USER with a password hash

Server -> Client : ERR packet or OK packet.

@enduml

As during normal connection, it is also possible that a post 4.1 client which

does not support pluggable authentication connects to an account which uses

@ref page_protocol_connection_phase_authentication_methods_old_password_authentication

In that case server will send

@ref page_protocol_connection_phase_packets_protocol_old_auth_switch_request

and expect the client to reply with

@ref sect_protocol_connection_phase_packets_protocol_handshake_response320

1. The client sends ::COM_CHANGE_USER packet with response for

@ref page_protocol_connection_phase_authentication_methods_native_password_authentication

2. The server replies with

@ref page_protocol_connection_phase_packets_protocol_old_auth_switch_request (0xFE byte)

3. The client sends response again, this time in the form required by

@ref page_protocol_connection_phase_authentication_methods_old_password_authentication

4. The server responds with an @ref page_protocol_basic_ok_packet and returns

to @ref page_protocol_command_phase or an @ref page_protocol_basic_err_packet

and disconnects

@startuml

Client -> Server : COM_CHANGE_USER with a password hash

Server -> Client : Old Switch Request Packet

Client -> Server : Old Password Auth Response

Server -> Client : ERR packet or OK packet

@enduml

@sa group_cs_capabilities_flags

@sa unknown_accounts

@subpage page_protocol_connection_phase_packets

@subpage page_protocol_connection_phase_authentication_methods

@subpage page_protocol_multi_factor_authentication_methods

*/

/**

@page page_protocol_basic_expired_passwords Expired Password

Since MySQL 5.6.7, a MySQL account can be expired.

If a account is expired, the session is in a restricted mode which

only permits SET PASSWORD = .. and similar SET commands.

Other statements will fail with an error like this:

~~~~~~~~

mysql> SELECT 1;

ERROR 1820 (HY000): You must SET PASSWORD before executing this statement

~~~~~~~~

Not all clients can properly deal with that error.

So on the protocol side exists a safeguard

::CLIENT_CAN_HANDLE_EXPIRED_PASSWORDS

@ref group_cs_capabilities_flags "capability flag" exists to prevent

clients from entering this "sandbox" mode.

Only clients that can handle this sandbox mode should report

::CLIENT_CAN_HANDLE_EXPIRED_PASSWORDS on.

Usually this means all interactive clients and all applications that got

adjusted to handle the relevant SQL error.

If a client is not setting that capability and it tries to login with an

account that has an expired password, the server will return an

@ref page_protocol_basic_err_packet for the

@ref page_protocol_connection_phase or the ::COM_CHANGE_USER request.

The idea is to block any activity until the password is reset.

@sa ::MYSQL_OPT_CAN_HANDLE_EXPIRED_PASSWORDS, mysql_options,

ACL_USER::password_expired, ACL_USER::password_lifetime,

acl_authenticate

*/

/**

@page page_protocol_connection_phase_authentication_methods Authentication Methods

To authenticate a user against the server the client server protocol employs one of

several authentication methods.

As of MySQL 5.5 the authentication method to be used to authenticate

connections to a particular MySQL account is indicated in the mysql.user table.

For earlier servers it's always mysql native authentication or

old password authentication depending on

the @ref CLIENT_RESERVED2 "CLIENT_SECURE_CONNECTION" flag.

Client and server negotiate what types of authentication they support as part of the

@ref page_protocol_connection_phase and

@ref sect_protocol_connection_phase_initial_handshake_auth_method.

Each authentication method consists of

* a client plugin name

* a server plugin name

* a specific exchange

The exchanged input and output data may either be sent as part of the

@ref page_protocol_connection_phase_packets_protocol_handshake and the

@ref page_protocol_connection_phase_packets_protocol_handshake_response

or as a part of the

@ref page_protocol_connection_phase_packets_protocol_auth_switch_request

and following packets. The structure is usually the same.

@section page_protocol_connection_phase_authentication_methods_limitations Limitations

While the overall exchange of data is free-form there are some limitations

in the initial handshake of the amount of data that can be exchanged without

causing an extra round trip:

<ul>

<li>

The `auth_plugin_data` field in

@ref page_protocol_connection_phase_packets_protocol_handshake packet can

only carry 255 bytes max (see @ref CLIENT_RESERVED2 "CLIENT_SECURE_CONNECTION").

</li><li>

The `auth_reponse_data` field in

@ref page_protocol_connection_phase_packets_protocol_handshake_response

packet can only carry 255 bytes max too if

@ref CLIENT_PLUGIN_AUTH_LENENC_CLIENT_DATA is not set.

</li><li>

The client-side plugin may not receive its initial data in the initial handshake

</li>

</ul>

@section page_protocol_connection_phase_authentication_methods_old_password_authentication Old Password Authentication

Authentication::Old:

<ul>

<li>

The server name is *mysql_old_password*

</li>

<li>

The client name is *mysql_old_password*

</li>

<li>

Client side requires an 8-byte random challenge from server

</li>

<li>

Client side sends a 8 byte response packet based on a proprietary algorithm.

</li>

</ul>

@note If the server announces

@ref page_protocol_connection_phase_authentication_methods_native_password_authentication

in the

@ref page_protocol_connection_phase_packets_protocol_handshake packet

the client may use the first 8 bytes of its 20-byte auth_plugin_data as input.

@startuml

Client->Server: 8 byte random data

Server->client: 8 byte scrambled password

@enduml

@warning The hashing algorithm used for this auth method is *broken* as

shown in CVE-2000-0981.

@subpage page_protocol_connection_phase_authentication_methods_native_password_authentication

@subpage page_caching_sha2_authentication_exchanges

@subpage page_protocol_connection_phase_authentication_methods_clear_text_password

@subpage page_protocol_connection_phase_authentication_methods_authentication_windows

@subpage page_webauthn_authentication_exchanges

*/

/**

@page page_protocol_connection_phase_packets_protocol_handshake Protocol::Handshake

Initial Handshake %Packet

When the client connects to the server the server sends a handshake

packet to the client. Depending on the server version and configuration

options different variants of the initial packet are sent.

To permit the server to add support for newer protocols, the first byte

defines the protocol version.

Since 3.21.0 the @ref page_protocol_connection_phase_packets_protocol_handshake_v10

is sent.

* @subpage page_protocol_connection_phase_packets_protocol_handshake_v9

* @subpage page_protocol_connection_phase_packets_protocol_handshake_v10

*/

/**

@page page_protocol_connection_phase_packets Connection Phase Packets

@subpage page_protocol_connection_phase_packets_protocol_handshake

@subpage page_protocol_connection_phase_packets_protocol_ssl_request

@subpage page_protocol_connection_phase_packets_protocol_handshake_response

@subpage page_protocol_connection_phase_packets_protocol_auth_switch_request

@subpage page_protocol_connection_phase_packets_protocol_old_auth_switch_request

@subpage page_protocol_connection_phase_packets_protocol_auth_switch_response

@subpage page_protocol_connection_phase_packets_protocol_auth_more_data

@subpage page_protocol_connection_phase_packets_protocol_auth_next_factor_request

*/

/**

@page page_webauthn_authentication_exchanges authentication_webauthn information

page_webauthn_authentication_exchanges

@section sect_webauthn_definition Definition

<ul>

<li>

The server side plugin name is *authentication_webauthn*

</li>

<li>

The client side plugin name is *authentication_webauthn_client*

</li>

<li>

Account - user account (user-host combination)

</li>

<li>

authentication_string - Transformation of Credential ID stored in mysql.user table

</li>

<li>

relying party ID - Unique name assigned to server by authentication_webauthn plugin

</li>

<li>

FIDO authenticator - A hardware token device

</li>

<li>

Salt - 32 byte long random data

</li>

<li>

Registration mode - Refers to state of connection where only ALTER USER is allowed

to do registration steps.

</li>

</ul>

@section sect_webauthn_info How authentication_webauthn works?

Plugin authentication_webauthn works in two phases.

<ul>

<li>

Registration of hardware token device

</li>

<li>

Authentication process

</li>

</ul>

Registration process:

This is a 2 step process for a given user account.

<ul>

<li>

Initiate registration step.

</li>

<li>

Finish registration step.

</li>

</ul>

Initiate registration:

--register-factor mysql client option initiates registration step.

<ol>

<li>

Client executes ALTER USER user() nth FACTOR INITIATE REGISTRATION;

</li>

<li>

Server sends a challenge comprising of 1 byte capability bit, 32 bytes random salt, relying party ID

Format of challenge is:

| 1 byte capability | length encoded 32 bytes random salt | length encoded relying party ID | length encoded user id (`user name`\@`host name`) |

Server also sends name of the client plugin - In this case authentication_webauthn_client.

</li>

<li>

Client receives challenge and client plugin name.

It then passes challenge to authentication_webauthn_client plugin

with option "registration_challenge" using mysql_plugin_options()

</li>

<li>

FIDO authenticator may prompt to enter device pin.

By default pin can be provided via standard input.

Alternatively, register a callback with option "authentication_webauthn_client_callback_get_password"

using mysql_plugin_options() to provide pin.

FIDO authenticator prompts to perform gesture action.

This message can be accessed via callback. Register a callback with option

"authentication_webauthn_client_messages_callback" using mysql_plugin_options()

</li>

<li>

Once gesture action (touching the token) is performed,

FIDO authenticator generates a public/private key pair, a credential ID(

X.509 certificate, signature) and authenticator data.

</li>

<li>

Client extracts credential ID(aka challenge response) from authentication_webauthn_client

plugin with option "registration_response" using mysql_plugin_get_option()

Response is encoded in base64. Format of challenge response is:

| 1 bytes capability | length encoded authenticator data | length encoded signature | length encoded x509 certificate | length encoded Client data JSON |

</li>

</ol>

Finish registration:

<ol>

<li>

Client executes ALTER USER user() nth FACTOR FINISH REGISTRATION SET CHALLENGE_RESPONSE AS '?';

parameter is binded to challenge response received during initiate registration step.

</li>

<li>

authentication_webauthn plugin verifies the challenge response and responds with an

@ref page_protocol_basic_ok_packet or rejects with @ref page_protocol_basic_err_packet

</li>

</ol>

@startuml

title Registration

participant server as "MySQL server"

participant client as "Client"

participant authenticator as "FIDO authenticator"

== Initiate registration ==

client -> server : connect

server -> client : OK packet. Connection is in registration mode where only ALTER USER command is allowed

client -> server : ALTER USER USER() nth FACTOR INITIATE REGISTRATION

server -> client : random challenge (capability, 32 byte random salt, relying party ID, user id)

client -> authenticator : random challenge

authenticator -> client : challenge response (capability, authenticator data, signature, x509 certificate, client data json)

== Finish registration ==

client -> server : ALTER USER USER() nth FACTOR FINISH REGISTRATION SET CHALLENGE_RESPONSE = 'challenge response'

server -> client : Ok packet upon successful verification of credential ID

@enduml

Authentication process:

Once initial authentication methods defined for user account are successful,

server initiates webauthn authentication process. This includes following steps:

<ol>

<li>

Server sends a 32 byte random salt, relying party ID to client.

Format is:

| 1 byte capability | length encoded 32 byte random salt | length encoded relying party ID |

</li>

<li>

Client receives them and checks if FIDO device has CTAP2(aka fido2) capability.

</li>

<li>

If FIDO device is not capable of CTAP2, client requests server to send credential ID.

Format is:

| 0x01 |

</li>

<li>

Server sends credential ID (or empty string if unavailable) to client.

Format is:

| length encoded credential ID |

</li>

<li>

If device has CTAP2 capability and if user has configured preserve-privacy option,

client prompts user to enter pin.

client then retrieves all credentials for given relying party ID from FIDO authenticator.

</li>

<li>

Client prompts user to choose from the list of credentials.

</li>

<li>

Client sends random salt, relying party ID and optionally credential ID OR

resident key identifier to FIDO authenticator.

</li>

<li>

FIDO authenticator prompts to perform gesture action.

</li>

<li>

For CTAP2 capable device, FIDO authenticator extracts one (in case of preserve-privacy

option) or all private key based on relying party ID and signs the challenge.

</li>

<li>

For non-CTAP2 devices, FIDO authenticator extracts private key based on

relying party ID and credential ID received from server and signs the challenge.

</li>

<li>

Client sends signed challenge to server.

Format:

| 0x02 | length encoded number of assertions | length encoded authenticator data | length encoded signature | ... | length encoded authenticator data | length encoded signature | client data json |

</li>

<li>

Server side webauthn authentication plugin verifies the signature with the

public key and responds with an @ref page_protocol_basic_ok_packet or with

@ref page_protocol_basic_err_packet

</li>

</ol>

@startuml

title Authentication

participant server as "MySQL server"

participant client as "Client"

participant authenticator as "FIDO authenticator"