Commit c3915ca2 authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman

LSM: add the example rootplug module

parent 70cafc1a
......@@ -80,6 +80,7 @@
/* host controllers we manage */
LIST_HEAD (usb_bus_list);
EXPORT_SYMBOL (usb_bus_list);
/* used when allocating bus numbers */
#define USB_MAXBUS 64
......@@ -90,6 +91,7 @@ static struct usb_busmap busmap;
/* used when updating list of hcds */
DECLARE_MUTEX (usb_bus_list_lock); /* exported only for usbfs */
EXPORT_SYMBOL (usb_bus_list_lock);
/* used when updating hcd data */
static spinlock_t hcd_data_lock = SPIN_LOCK_UNLOCKED;
......
......@@ -22,5 +22,15 @@ config SECURITY_CAPABILITIES
This enables the "default" Linux capabilities functionality.
If you are unsure how to answer this question, answer Y.
config SECURITY_ROOTPLUG
tristate "Root Plug Support"
depends on SECURITY!=n
help
This is a sample LSM module that should only be used as such.
It enables control over processes being created by root users
if a specific USB device is not present in the system.
If you are unsure how to answer this question, answer N.
endmenu
......@@ -13,5 +13,6 @@ endif
# Object file lists
obj-$(CONFIG_SECURITY) += security.o dummy.o
obj-$(CONFIG_SECURITY_CAPABILITIES) += capability.o
obj-$(CONFIG_SECURITY_ROOTPLUG) += root_plug.o
include $(TOPDIR)/Rules.make
/*
* 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.
*
* 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/config.h>
#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_PARM(vendor_id, "h");
MODULE_PARM_DESC(vendor_id, "USB Vendor ID of device to look for");
MODULE_PARM(product_id, "h");
MODULE_PARM_DESC(product_id, "USB Product ID of device to look for");
/* should we print out debug messages */
static int debug = 0;
MODULE_PARM(debug, "i");
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 dbg(fmt, arg...) \
do { \
if (debug) \
printk(KERN_DEBUG "%s: %s: " fmt , \
MY_NAME , __FUNCTION__ , \
## arg); \
} while (0)
extern struct list_head usb_bus_list;
extern struct semaphore usb_bus_list_lock;
static int match_device (struct usb_device *dev)
{
int retval = -ENODEV;
int child;
dbg ("looking at vendor %d, product %d\n",
dev->descriptor.idVendor,
dev->descriptor.idProduct);
/* see if this device matches */
if ((dev->descriptor.idVendor == vendor_id) &&
(dev->descriptor.idProduct == product_id)) {
dbg ("found the device!\n");
retval = 0;
goto exit;
}
/* look through all of the children of this device */
for (child = 0; child < dev->maxchild; ++child) {
if (dev->children[child]) {
retval = match_device (dev->children[child]);
if (retval == 0)
goto exit;
}
}
exit:
return retval;
}
static int find_usb_device (void)
{
struct list_head *buslist;
struct usb_bus *bus;
int retval = -ENODEV;
down (&usb_bus_list_lock);
for (buslist = usb_bus_list.next;
buslist != &usb_bus_list;
buslist = buslist->next) {
bus = container_of (buslist, struct usb_bus, bus_list);
retval = match_device(bus->root_hub);
if (retval == 0)
goto exit;
}
exit:
up (&usb_bus_list_lock);
return retval;
}
static int rootplug_bprm_check_security (struct linux_binprm *bprm)
{
dbg ("file %s, e_uid = %d, e_gid = %d\n",
bprm->filename, bprm->e_uid, bprm->e_gid);
if (bprm->e_gid == 0) {
if (find_usb_device() != 0) {
dbg ("e_gid = 0, and device not found, "
"task not allowed to run...\n");
return -EPERM;
}
}
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_compute_creds = cap_bprm_compute_creds,
.bprm_set_security = cap_bprm_set_security,
.task_post_setuid = cap_task_post_setuid,
.task_kmod_set_label = cap_task_kmod_set_label,
.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");
}
module_init (rootplug_init);
module_exit (rootplug_exit);
MODULE_DESCRIPTION("Root Plug sample LSM module, written for Linux Journal article");
MODULE_LICENSE("GPL");
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment