LSM: add the example rootplug module
diff -Nru a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
--- a/drivers/usb/core/hcd.c Thu Dec 5 01:19:10 2002
+++ b/drivers/usb/core/hcd.c Thu Dec 5 01:19:10 2002
@@ -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 @@
/* 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;
diff -Nru a/security/Kconfig b/security/Kconfig
--- a/security/Kconfig Thu Dec 5 01:19:10 2002
+++ b/security/Kconfig Thu Dec 5 01:19:10 2002
@@ -22,5 +22,15 @@
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
diff -Nru a/security/Makefile b/security/Makefile
--- a/security/Makefile Thu Dec 5 01:19:10 2002
+++ b/security/Makefile Thu Dec 5 01:19:10 2002
@@ -13,5 +13,6 @@
# 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
diff -Nru a/security/root_plug.c b/security/root_plug.c
--- /dev/null Wed Dec 31 16:00:00 1969
+++ b/security/root_plug.c Thu Dec 5 01:19:10 2002
@@ -0,0 +1,189 @@
+/*
+ * 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");
+
-
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