1 files changed, 142 insertions, 0 deletions

diff --git a/security/root_plug.c b/security/root_plug.c
new file mode 100644
index 000000000000..07651def2f78
--- /dev/null
+++ b/security/root_plug.c
@@ -0,0 +1,142 @@
+/*
+ * 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/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_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");
+