[linux.git] / security / root_plug.c

/*
 * Root Plug sample LSM module
 *
 * Originally written for a Linux Journal.
 *
 * Copyright (C) 2002 Greg Kroah-Hartman <[email protected]>
 *
 * 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/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/security.h>
#include <linux/usb.h>

/* flag to keep track of how we were registered */
static int secondary;

/* 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_PARM_DESC(vendor_id, "USB Vendor ID of device to look for");

module_param(product_id, uint, 0400);
MODULE_PARM_DESC(product_id, "USB Product ID of device to look for");

/* should we print out debug messages */
static int debug = 0;

module_param(debug, bool, 0600);
MODULE_PARM_DESC(debug, "Debug enabled or not");

#if defined(CONFIG_SECURITY_ROOTPLUG_MODULE)
#define MY_NAME THIS_MODULE->name
#else
#define MY_NAME "root_plug"
#endif

#define root_dbg(fmt, arg...)					\
	do {							\
		if (debug)					\
			printk(KERN_DEBUG "%s: %s: " fmt ,	\
				MY_NAME , __FUNCTION__ , 	\
				## 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 =			cap_ptrace,
	.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,

	.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");
		/* try registering with primary module */
		if (mod_reg_security (MY_NAME, &rootplug_security_ops)) {
			printk (KERN_INFO "Failure registering Root Plug "
				" module with primary security module.\n");
			return -EINVAL;
		}
		secondary = 1;
	}
	printk (KERN_INFO "Root Plug module initialized, "
		"vendor_id = %4.4x, product id = %4.4x\n", vendor_id, product_id);
	return 0;
}

static void __exit rootplug_exit (void)
{
	/* remove ourselves from the security framework */
	if (secondary) {
		if (mod_unreg_security (MY_NAME, &rootplug_security_ops))
			printk (KERN_INFO "Failure unregistering Root Plug "
				" module with primary module.\n");
	} else { 
		if (unregister_security (&rootplug_security_ops)) {
			printk (KERN_INFO "Failure unregistering Root Plug "
				"module with the kernel\n");
		}
	}
	printk (KERN_INFO "Root Plug module removed\n");
}

security_initcall (rootplug_init);
module_exit (rootplug_exit);

MODULE_DESCRIPTION("Root Plug sample LSM module, written for Linux Journal article");
MODULE_LICENSE("GPL");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Root Plug sample LSM module
	3	*
	4	* Originally written for a Linux Journal.
	5	*
	6	* Copyright (C) 2002 Greg Kroah-Hartman <[email protected]>
	7	*
	8	* Prevents any programs running with egid == 0 if a specific USB device
	9	* is not present in the system. Yes, it can be gotten around, but is a
	10	* nice starting point for people to play with, and learn the LSM
	11	* interface.
	12	*
	13	* If you want to turn this into something with a semblance of security,
	14	* you need to hook the task_* functions also.
	15	*
	16	* See http://www.linuxjournal.com/article.php?sid=6279 for more information
	17	* about this code.
	18	*
	19	* This program is free software; you can redistribute it and/or
	20	* modify it under the terms of the GNU General Public License as
	21	* published by the Free Software Foundation, version 2 of the
	22	* License.
	23	*/
	24
1da177e4 LT	25	#include <linux/module.h>
	26	#include <linux/kernel.h>
	27	#include <linux/init.h>
	28	#include <linux/security.h>
	29	#include <linux/usb.h>
	30
	31	/* flag to keep track of how we were registered */
	32	static int secondary;
	33
	34	/* default is a generic type of usb to serial converter */
	35	static int vendor_id = 0x0557;
	36	static int product_id = 0x2008;
	37
	38	module_param(vendor_id, uint, 0400);
	39	MODULE_PARM_DESC(vendor_id, "USB Vendor ID of device to look for");
	40
	41	module_param(product_id, uint, 0400);
	42	MODULE_PARM_DESC(product_id, "USB Product ID of device to look for");
	43
	44	/* should we print out debug messages */
	45	static int debug = 0;
	46
	47	module_param(debug, bool, 0600);
	48	MODULE_PARM_DESC(debug, "Debug enabled or not");
	49
	50	#if defined(CONFIG_SECURITY_ROOTPLUG_MODULE)
	51	#define MY_NAME THIS_MODULE->name
	52	#else
	53	#define MY_NAME "root_plug"
	54	#endif
	55
	56	#define root_dbg(fmt, arg...) \
	57	do { \
	58	if (debug) \
	59	printk(KERN_DEBUG "%s: %s: " fmt , \
	60	MY_NAME , __FUNCTION__ , \
	61	## arg); \
	62	} while (0)
	63
	64	static int rootplug_bprm_check_security (struct linux_binprm *bprm)
	65	{
	66	struct usb_device *dev;
	67
	68	root_dbg("file %s, e_uid = %d, e_gid = %d\n",
	69	bprm->filename, bprm->e_uid, bprm->e_gid);
	70
	71	if (bprm->e_gid == 0) {
	72	dev = usb_find_device(vendor_id, product_id);
	73	if (!dev) {
	74	root_dbg("e_gid = 0, and device not found, "
	75	"task not allowed to run...\n");
	76	return -EPERM;
	77	}
	78	usb_put_dev(dev);
	79	}
	80
	81	return 0;
	82	}
	83
	84	static struct security_operations rootplug_security_ops = {
	85	/* Use the capability functions for some of the hooks */
	86	.ptrace = cap_ptrace,
	87	.capget = cap_capget,
	88	.capset_check = cap_capset_check,
89	.capset_set = cap_capset_set,
90	.capable = cap_capable,
91
92	.bprm_apply_creds = cap_bprm_apply_creds,
93	.bprm_set_security = cap_bprm_set_security,
94
95	.task_post_setuid = cap_task_post_setuid,
96	.task_reparent_to_init = cap_task_reparent_to_init,
97
98	.bprm_check_security = rootplug_bprm_check_security,
99	};
100
101	static int __init rootplug_init (void)
102	{
103	/* register ourselves with the security framework */
104	if (register_security (&rootplug_security_ops)) {
105	printk (KERN_INFO
106	"Failure registering Root Plug module with the kernel\n");
107	/* try registering with primary module */
108	if (mod_reg_security (MY_NAME, &rootplug_security_ops)) {
109	printk (KERN_INFO "Failure registering Root Plug "
110	" module with primary security module.\n");
111	return -EINVAL;
112	}
113	secondary = 1;
114	}
115	printk (KERN_INFO "Root Plug module initialized, "
116	"vendor_id = %4.4x, product id = %4.4x\n", vendor_id, product_id);
117	return 0;
118	}
119
120	static void __exit rootplug_exit (void)
121	{
122	/* remove ourselves from the security framework */
123	if (secondary) {
124	if (mod_unreg_security (MY_NAME, &rootplug_security_ops))
125	printk (KERN_INFO "Failure unregistering Root Plug "
126	" module with primary module.\n");
127	} else {
128	if (unregister_security (&rootplug_security_ops)) {
129	printk (KERN_INFO "Failure unregistering Root Plug "
130	"module with the kernel\n");
131	}
132	}
133	printk (KERN_INFO "Root Plug module removed\n");
134	}
135
136	security_initcall (rootplug_init);
137	module_exit (rootplug_exit);
138
139	MODULE_DESCRIPTION("Root Plug sample LSM module, written for Linux Journal article");
140	MODULE_LICENSE("GPL");
141