android_kernel_xiaomi_sm8350/security/root_plug.c
James Morris 20510f2f4e security: Convert LSM into a static interface
Convert LSM into a static interface, as the ability to unload a security
module is not required by in-tree users and potentially complicates the
overall security architecture.

Needlessly exported LSM symbols have been unexported, to help reduce API
abuse.

Parameters for the capability and root_plug modules are now specified
at boot.

The SECURITY_FRAMEWORK_VERSION macro has also been removed.

In a nutshell, there is no safe way to unload an LSM.  The modular interface
is thus unecessary and broken infrastructure.  It is used only by out-of-tree
modules, which are often binary-only, illegal, abusive of the API and
dangerous, e.g.  silently re-vectoring SELinux.

[akpm@linux-foundation.org: cleanups]
[akpm@linux-foundation.org: USB Kconfig fix]
[randy.dunlap@oracle.com: fix LSM kernel-doc]
Signed-off-by: James Morris <jmorris@namei.org>
Acked-by: Chris Wright <chrisw@sous-sol.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: "Serge E. Hallyn" <serue@us.ibm.com>
Acked-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-17 08:43:07 -07:00

113 lines
3.0 KiB
C

/*
* 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/kernel.h>
#include <linux/init.h>
#include <linux/security.h>
#include <linux/usb.h>
#include <linux/moduleparam.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_param(product_id, uint, 0400);
/* should we print out debug messages */
static int debug = 0;
module_param(debug, bool, 0600);
#define MY_NAME "root_plug"
#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;
}
security_initcall (rootplug_init);