MDEV-22974: mysql_native_password make "invalid" valid

Per b9f3f068, mysql_system_tables_data.sql creates
a mysql_native_password with a salted hash of "invalid" so that `set password`
will detect a native password can be applied:.

SHOW CREATE USER; diligently uses this value in its output
generating the SQL:

   MariaDB [(none)]> show create user;

   +---------------------------------------------------------------------------------------------------+
   | CREATE USER for dan@localhost                                                                     |
   +---------------------------------------------------------------------------------------------------+
   | CREATE USER `dan`@`localhost` IDENTIFIED VIA mysql_native_password USING 'invalid' OR unix_socket |
   +---------------------------------------------------------------------------------------------------+

Attempting to execute this before this patch results in:

  MariaDB [(none)]>  CREATE USER `dan2`@`localhost` IDENTIFIED VIA mysql_native_password USING 'invalid' OR unix_socket;
  ERROR 1372 (HY000): Password hash should be a 41-digit hexadecimal number

As such, deep the implementation of mysql_native_password we make "invalid" valid (pun intended)
such that the above create user will succeed. We do this by storing
"*THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE" (credit: Oracle MySQL), that is of an INCORRECT
length for a scramble.

In native_password_authenticate we check the length of this cached value
and immediately fail if it is anything other than the scramble length.

native_password_get_salt is only called in the context of set_user_salt, so all setting of native
passwords to hashed content of 'invalid', quite literally create an invalid password.

So other forms of "invalid" are valid SQL in creating invalid passwords:

   MariaDB [(none)]> set password = 'invalid';
   Query OK, 0 rows affected (0.001 sec)

   MariaDB [(none)]> alter user dan@localhost IDENTIFIED BY PASSWORD 'invalid';
   Query OK, 0 rows affected (0.000 sec)

closes #1628

Reviewer: serg@mariadb.com

mysql-test/main/alter_user.result

@@ -61,6 +61,10 @@ alter user foo identified by password '*88C89BE093D4ECF72D039F62EBB7477EA1FD4D63
 select * from mysql.user where user = 'foo';
 Host	User	Password	Select_priv	Insert_priv	Update_priv	Delete_priv	Create_priv	Drop_priv	Reload_priv	Shutdown_priv	Process_priv	File_priv	Grant_priv	References_priv	Index_priv	Alter_priv	Show_db_priv	Super_priv	Create_tmp_table_priv	Lock_tables_priv	Execute_priv	Repl_slave_priv	Repl_client_priv	Create_view_priv	Show_view_priv	Create_routine_priv	Alter_routine_priv	Create_user_priv	Event_priv	Trigger_priv	Create_tablespace_priv	Delete_history_priv	ssl_type	ssl_cipher	x509_issuer	x509_subject	max_questions	max_updates	max_connections	max_user_connections	plugin	authentication_string	password_expired	is_role	default_role	max_statement_time
 %	foo	*88C89BE093D4ECF72D039F62EBB7477EA1FD4D63	N	N	N	N	N	N	N	N	N	N	N	N	N	N	N	Y	N	N	N	N	N	N	N	N	N	Y	N	N	N	N					0	0	0	0	mysql_native_password	*88C89BE093D4ECF72D039F62EBB7477EA1FD4D63	N	N		0.000000
+alter user foo identified by password 'invalid';
+select * from mysql.user where user = 'foo';
+Host	User	Password	Select_priv	Insert_priv	Update_priv	Delete_priv	Create_priv	Drop_priv	Reload_priv	Shutdown_priv	Process_priv	File_priv	Grant_priv	References_priv	Index_priv	Alter_priv	Show_db_priv	Super_priv	Create_tmp_table_priv	Lock_tables_priv	Execute_priv	Repl_slave_priv	Repl_client_priv	Create_view_priv	Show_view_priv	Create_routine_priv	Alter_routine_priv	Create_user_priv	Event_priv	Trigger_priv	Create_tablespace_priv	Delete_history_priv	ssl_type	ssl_cipher	x509_issuer	x509_subject	max_questions	max_updates	max_connections	max_user_connections	plugin	authentication_string	password_expired	is_role	default_role	max_statement_time
+%	foo	invalid	N	N	N	N	N	N	N	N	N	N	N	N	N	N	N	Y	N	N	N	N	N	N	N	N	N	Y	N	N	N	N					0	0	0	0	mysql_native_password	invalid	N	N		0.000000
 alter user foo identified with 'somecoolplugin';
 ERROR HY000: Operation ALTER USER failed for 'foo'@'%'
 show warnings;

mysql-test/main/alter_user.test

@@ -55,6 +55,9 @@ select * from mysql.user where user = 'foo';
 alter user foo identified by password '*88C89BE093D4ECF72D039F62EBB7477EA1FD4D63';
 select * from mysql.user where user = 'foo';
 
+alter user foo identified by password 'invalid';
+select * from mysql.user where user = 'foo';
+
 --error ER_CANNOT_USER
 alter user foo identified with 'somecoolplugin';
 show warnings;

mysql-test/main/set_password.result

 set global secure_auth=0;
 create user natauth@localhost identified via 'mysql_native_password' using '*94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29';
+create user invalidauth@localhost identified via 'mysql_native_password' using 'invalid';
 create user newpass@localhost identified by password '*94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29';
+create user invalidpass@localhost identified by password 'invalid';
 create user newpassnat@localhost identified via 'mysql_native_password';
 set password for newpassnat@localhost = '*94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29';
+create user invalidpassnat@localhost identified by password 'invalid';
+set password for invalidpassnat@localhost = 'invalid';
 create user oldauth@localhost identified with 'mysql_old_password' using '378b243e220ca493';
 create user oldpass@localhost identified by password '378b243e220ca493';
 create user oldpassold@localhost identified with 'mysql_old_password';
 set password for oldpassold@localhost = '378b243e220ca493';
 select user, host, password, plugin, authentication_string from mysql.user where user != 'root';
 User	Host	Password	plugin	authentication_string
+invalidauth	localhost	invalid	mysql_native_password	invalid
+invalidpass	localhost	invalid	mysql_native_password	invalid
+invalidpassnat	localhost	invalid	mysql_native_password	invalid
 mariadb.sys	localhost		mysql_native_password	
 natauth	localhost	*94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29	mysql_native_password	*94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29
 newpass	localhost	*94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29	mysql_native_password	*94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29
@@ -87,6 +94,9 @@ set password for oldpass@localhost = PASSWORD('test2');
 set password for oldpassold@localhost = PASSWORD('test2');
 select user, host, password, plugin, authentication_string from mysql.user where user != 'root';
 User	Host	Password	plugin	authentication_string
+invalidauth	localhost	invalid	mysql_native_password	invalid
+invalidpass	localhost	invalid	mysql_native_password	invalid
+invalidpassnat	localhost	invalid	mysql_native_password	invalid
 mariadb.sys	localhost		mysql_native_password	
 natauth	localhost	*7CEB3FDE5F7A9C4CE5FBE610D7D8EDA62EBE5F4E	mysql_native_password	*7CEB3FDE5F7A9C4CE5FBE610D7D8EDA62EBE5F4E
 newpass	localhost	*7CEB3FDE5F7A9C4CE5FBE610D7D8EDA62EBE5F4E	mysql_native_password	*7CEB3FDE5F7A9C4CE5FBE610D7D8EDA62EBE5F4E
@@ -141,6 +151,15 @@ select current_user();
 current_user()
 newpassnat@localhost
 disconnect con;
+connect(localhost,invalidauth,invalid,test,MASTER_PORT,MASTER_SOCKET);
+connect con,localhost,invalidauth,invalid,;
+ERROR 28000: Access denied for user 'invalidauth'@'localhost' (using password: YES)
+connect(localhost,invalidpass,invalid,test,MASTER_PORT,MASTER_SOCKET);
+connect con,localhost,invalidpass,invalid,;
+ERROR 28000: Access denied for user 'invalidpass'@'localhost' (using password: YES)
+connect(localhost,invalidpassnat,invalid,test,MASTER_PORT,MASTER_SOCKET);
+connect con,localhost,invalidpassnat,invalid,;
+ERROR 28000: Access denied for user 'invalidpassnat'@'localhost' (using password: YES)
 connect con,localhost,oldauth,test2,;
 select current_user();
 current_user()
@@ -158,6 +177,7 @@ oldpassold@localhost
 disconnect con;
 connection default;
 drop user natauth@localhost, newpass@localhost, newpassnat@localhost;
+drop user invalidauth@localhost, invalidpass@localhost, invalidpassnat@localhost;
 drop user oldauth@localhost, oldpass@localhost, oldpassold@localhost;
 set global secure_auth=default;
 # switching from mysql.global_priv to mysql.user

mysql-test/main/set_password.test

@@ -12,11 +12,18 @@ set global secure_auth=0;
 # The hash (old and new) is for 'test'
 create user natauth@localhost identified via 'mysql_native_password' using '*94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29';
 
+create user invalidauth@localhost identified via 'mysql_native_password' using 'invalid';
+
 create user newpass@localhost identified by password '*94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29';
 
+create user invalidpass@localhost identified by password 'invalid';
+
 create user newpassnat@localhost identified via 'mysql_native_password';
 set password for newpassnat@localhost = '*94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29';
 
+create user invalidpassnat@localhost identified by password 'invalid';
+set password for invalidpassnat@localhost = 'invalid';
+
 create user oldauth@localhost identified with 'mysql_old_password' using '378b243e220ca493';
 
 create user oldpass@localhost identified by password '378b243e220ca493';
@@ -114,6 +121,17 @@ select current_user();
 --connect(con,localhost,newpassnat,test2,)
 select current_user();
 --disconnect con
+
+--replace_result $MASTER_MYSOCK MASTER_SOCKET $MASTER_MYPORT MASTER_PORT
+--error ER_ACCESS_DENIED_ERROR
+--connect(con,localhost,invalidauth,invalid,)
+--replace_result $MASTER_MYSOCK MASTER_SOCKET $MASTER_MYPORT MASTER_PORT
+--error ER_ACCESS_DENIED_ERROR
+--connect(con,localhost,invalidpass,invalid,)
+--replace_result $MASTER_MYSOCK MASTER_SOCKET $MASTER_MYPORT MASTER_PORT
+--error ER_ACCESS_DENIED_ERROR
+--connect(con,localhost,invalidpassnat,invalid,)
+
 --connect(con,localhost,oldauth,test2,)
 select current_user();
 --disconnect con
@@ -126,6 +144,7 @@ select current_user();
 
 --connection default
 drop user natauth@localhost, newpass@localhost, newpassnat@localhost;
+drop user invalidauth@localhost, invalidpass@localhost, invalidpassnat@localhost;
 drop user oldauth@localhost, oldpass@localhost, oldpassold@localhost;
 set global secure_auth=default;
 

sql/sql_acl.cc

@@ -14166,7 +14166,7 @@ static int native_password_authenticate(MYSQL_PLUGIN_VIO *vio,
   info->password_used= PASSWORD_USED_YES;
   if (pkt_len == SCRAMBLE_LENGTH)
   {
-    if (!info->auth_string_length)
+    if (info->auth_string_length != SCRAMBLE_LENGTH)
       DBUG_RETURN(CR_AUTH_USER_CREDENTIALS);
 
     if (check_scramble(pkt, thd->scramble, (uchar*)info->auth_string))
@@ -14193,9 +14193,13 @@ static int native_password_make_scramble(const char *password,
   return 0;
 }
 
+/* As this contains is a string of not a valid SCRAMBLE_LENGTH */
+static const char invalid_password[] = "*THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE";
+
 static int native_password_get_salt(const char *hash, size_t hash_length,
                                     unsigned char *out, size_t *out_length)
 {
+  DBUG_ASSERT(sizeof(invalid_password) > SCRAMBLE_LENGTH);
   DBUG_ASSERT(*out_length >= SCRAMBLE_LENGTH);
   if (hash_length == 0)
   {
@@ -14205,6 +14209,12 @@ static int native_password_get_salt(const char *hash, size_t hash_length,
 
   if (hash_length != SCRAMBLED_PASSWORD_CHAR_LENGTH)
   {
+    if (hash_length == 7 && strcmp(hash, "invalid") == 0)
+    {
+      memcpy(out, invalid_password, SCRAMBLED_PASSWORD_CHAR_LENGTH);
+      *out_length= SCRAMBLED_PASSWORD_CHAR_LENGTH;
+      return 0;
+    }
     my_error(ER_PASSWD_LENGTH, MYF(0), SCRAMBLED_PASSWORD_CHAR_LENGTH);
     return 1;
   }