selinux: handle files opened with flags 3 by checking ioctl permission
[linux-2.6.git] / security / root_plug.c
1 /*
2  * Root Plug sample LSM module
3  *
4  * Originally written for a Linux Journal.
5  *
6  * Copyright (C) 2002 Greg Kroah-Hartman <greg@kroah.com>
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
25 #include <linux/kernel.h>
26 #include <linux/init.h>
27 #include <linux/security.h>
28 #include <linux/usb.h>
29 #include <linux/moduleparam.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_param(product_id, uint, 0400);
40
41 /* should we print out debug messages */
42 static int debug = 0;
43
44 module_param(debug, bool, 0600);
45
46 #define MY_NAME "root_plug"
47
48 #define root_dbg(fmt, arg...)                                   \
49         do {                                                    \
50                 if (debug)                                      \
51                         printk(KERN_DEBUG "%s: %s: " fmt ,      \
52                                 MY_NAME , __FUNCTION__ ,        \
53                                 ## arg);                        \
54         } while (0)
55
56 static int rootplug_bprm_check_security (struct linux_binprm *bprm)
57 {
58         struct usb_device *dev;
59
60         root_dbg("file %s, e_uid = %d, e_gid = %d\n",
61                  bprm->filename, bprm->e_uid, bprm->e_gid);
62
63         if (bprm->e_gid == 0) {
64                 dev = usb_find_device(vendor_id, product_id);
65                 if (!dev) {
66                         root_dbg("e_gid = 0, and device not found, "
67                                  "task not allowed to run...\n");
68                         return -EPERM;
69                 }
70                 usb_put_dev(dev);
71         }
72
73         return 0;
74 }
75
76 static struct security_operations rootplug_security_ops = {
77         /* Use the capability functions for some of the hooks */
78         .ptrace =                       cap_ptrace,
79         .capget =                       cap_capget,
80         .capset_check =                 cap_capset_check,
81         .capset_set =                   cap_capset_set,
82         .capable =                      cap_capable,
83
84         .bprm_apply_creds =             cap_bprm_apply_creds,
85         .bprm_set_security =            cap_bprm_set_security,
86
87         .task_post_setuid =             cap_task_post_setuid,
88         .task_reparent_to_init =        cap_task_reparent_to_init,
89
90         .bprm_check_security =          rootplug_bprm_check_security,
91 };
92
93 static int __init rootplug_init (void)
94 {
95         /* register ourselves with the security framework */
96         if (register_security (&rootplug_security_ops)) {
97                 printk (KERN_INFO 
98                         "Failure registering Root Plug module with the kernel\n");
99                 /* try registering with primary module */
100                 if (mod_reg_security (MY_NAME, &rootplug_security_ops)) {
101                         printk (KERN_INFO "Failure registering Root Plug "
102                                 " module with primary security module.\n");
103                         return -EINVAL;
104                 }
105                 secondary = 1;
106         }
107         printk (KERN_INFO "Root Plug module initialized, "
108                 "vendor_id = %4.4x, product id = %4.4x\n", vendor_id, product_id);
109         return 0;
110 }
111
112 security_initcall (rootplug_init);