/* * Root Plug sample LSM module * * Originally written for a Linux Journal. * * Copyright (C) 2002 Greg Kroah-Hartman <greg@kroah.com> * * Prevents any programs running with egid == 0 if a specific USB device * is not present in the system.  Yes, it can be gotten around, but is a * nice starting point for people to play with, and learn the LSM * interface. * * If you want to turn this into something with a semblance of security, * you need to hook the task_* functions also. * * See http://www.linuxjournal.com/article.php?sid=6279 for more information * about this code. * *	This program is free software; you can redistribute it and/or *	modify it under the terms of the GNU General Public License as *	published by the Free Software Foundation, version 2 of the *	License. */ #include <linux/kernel.h>#include <linux/init.h>#include <linux/security.h>#include <linux/usb.h>#include <linux/moduleparam.h> /* default is a generic type of usb to serial converter */static int vendor_id = 0x0557;static int product_id = 0x2008; module_param(vendor_id, uint, 0400);module_param(product_id, uint, 0400); /* should we print out debug messages */static int debug = 0; module_param(debug, bool, 0600); #define MY_NAME "root_plug" #define root_dbg(fmt, arg...)					\	do {							\		if (debug)					\			printk(KERN_DEBUG "%s: %s: " fmt ,	\				MY_NAME , __func__ , 	\				## arg);			\	} while (0) static int rootplug_bprm_check_security (struct linux_binprm *bprm){	struct usb_device *dev; 	root_dbg("file %s, e_uid = %d, e_gid = %d\n",		 bprm->filename, bprm->e_uid, bprm->e_gid); 	if (bprm->e_gid == 0) {		dev = usb_find_device(vendor_id, product_id);		if (!dev) {			root_dbg("e_gid = 0, and device not found, "				 "task not allowed to run...\n");			return -EPERM;		}		usb_put_dev(dev);	} 	return 0;} static struct security_operations rootplug_security_ops = {	/* Use the capability functions for some of the hooks */	.ptrace_may_access =		cap_ptrace_may_access,	.ptrace_traceme =		cap_ptrace_traceme,	.capget =			cap_capget,	.capset_check =			cap_capset_check,	.capset_set =			cap_capset_set,	.capable =			cap_capable, 	.bprm_apply_creds =		cap_bprm_apply_creds,	.bprm_set_security =		cap_bprm_set_security, 	.task_post_setuid =		cap_task_post_setuid,	.task_reparent_to_init =	cap_task_reparent_to_init,	.task_prctl =			cap_task_prctl, 	.bprm_check_security =		rootplug_bprm_check_security,}; static int __init rootplug_init (void){	/* register ourselves with the security framework */	if (register_security (&rootplug_security_ops)) {		printk (KERN_INFO 			"Failure registering Root Plug module with the kernel\n");			return -EINVAL;	}	printk (KERN_INFO "Root Plug module initialized, "		"vendor_id = %4.4x, product id = %4.4x\n", vendor_id, product_id);	return 0;} security_initcall (rootplug_init);