forked from Minki/linux
5cd9c58fbe
Fix the setting of PF_SUPERPRIV by __capable() as it could corrupt the flags
the target process if that is not the current process and it is trying to
change its own flags in a different way at the same time.
__capable() is using neither atomic ops nor locking to protect t->flags. This
patch removes __capable() and introduces has_capability() that doesn't set
PF_SUPERPRIV on the process being queried.
This patch further splits security_ptrace() in two:
(1) security_ptrace_may_access(). This passes judgement on whether one
process may access another only (PTRACE_MODE_ATTACH for ptrace() and
PTRACE_MODE_READ for /proc), and takes a pointer to the child process.
current is the parent.
(2) security_ptrace_traceme(). This passes judgement on PTRACE_TRACEME only,
and takes only a pointer to the parent process. current is the child.
In Smack and commoncap, this uses has_capability() to determine whether
the parent will be permitted to use PTRACE_ATTACH if normal checks fail.
This does not set PF_SUPERPRIV.
Two of the instances of __capable() actually only act on current, and so have
been changed to calls to capable().
Of the places that were using __capable():
(1) The OOM killer calls __capable() thrice when weighing the killability of a
process. All of these now use has_capability().
(2) cap_ptrace() and smack_ptrace() were using __capable() to check to see
whether the parent was allowed to trace any process. As mentioned above,
these have been split. For PTRACE_ATTACH and /proc, capable() is now
used, and for PTRACE_TRACEME, has_capability() is used.
(3) cap_safe_nice() only ever saw current, so now uses capable().
(4) smack_setprocattr() rejected accesses to tasks other than current just
after calling __capable(), so the order of these two tests have been
switched and capable() is used instead.
(5) In smack_file_send_sigiotask(), we need to allow privileged processes to
receive SIGIO on files they're manipulating.
(6) In smack_task_wait(), we let a process wait for a privileged process,
whether or not the process doing the waiting is privileged.
I've tested this with the LTP SELinux and syscalls testscripts.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Andrew G. Morgan <morgan@kernel.org>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: James Morris <jmorris@namei.org>
106 lines
2.8 KiB
C
106 lines
2.8 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>
|
|
|
|
/* 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 , __func__ , \
|
|
## 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_may_access = cap_ptrace_may_access,
|
|
.ptrace_traceme = cap_ptrace_traceme,
|
|
.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,
|
|
.task_prctl = cap_task_prctl,
|
|
|
|
.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");
|
|
return -EINVAL;
|
|
}
|
|
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);
|