Best Practice

There are two potential security issues with supporting the LOCAL version of LOAD DATA statements:

• The transfer of the file from the client host to the server host is initiated by the MySQL server. In theory, a patched server could be built that would tell the client program to transfer a file of the server's choosing rather than the file named by the client in the LOAD DATA statement. Such a server could access any file on the client host to which the client user has read access.

• In a Web environment where the clients are connecting from a Web server, a user could use LOAD DATA LOCAL to read any files that the Web server process has read access to (assuming that a user could run any command against the SQL server). In this environment, the client with respect to the MySQL server actually is the Web server, not the program being run by the user connecting to the Web server.

To deal with these problems, we changed how LOAD DATA LOCAL is handled as of MySQL 3.23.49 and MySQL 4.0.2 (4.0.13 on Windows):

• By default, all MySQL clients and libraries in binary distributions are now compiled with the --enable-local-infile option, to be compatible with MySQL 3.23.48 and before.

• If you build MySQL from source but don't use the --enable-local-infile option to configure, LOAD DATA LOCAL cannot be used by any client unless it is written explicitly to invoke mysql_options(...MYSQL_OPT_LOCAL_INFILE, 0).

• You can disable all LOAD DATA LOCAL commands from the server side by starting mysqld with the --local-infile=0 option.

• For the mysql command-line client, LOAD DATA LOCAL can be enabled by specifying the --local-infile[=1] option, or disabled with the --local-infile=0 option. Similarly, for mysqlimport, the --local or -L option enables local data file loading. In any case, successful use of a local loading operation requires that the server is enabled to allow it.

• If you use LOAD DATA LOCAL in Perl scripts or other programs that read the [client] group from option files, you can add the local-infile=1 option to that group. However, to keep this from causing problems for programs that do not understand local-infile, specify it using the loose- prefix:

  [client]
  loose-local-infile=1

• If LOAD DATA LOCAL INFILE is disabled, either in the server or the client, a client that attempts to issue such a statement receives the following error message:

  ERROR 1148: The used command is not allowed with this MySQL version