Re: [kernel-hardening] [RFC V2 0/6] add more kernel pointer filter options

[Tobin C. Harding]

On Sun, Oct 01, 2017 at 11:06:44AM +1100, Tobin C. Harding wrote:
> Version 2 of Greg's patch series with changes made as suggested by comments to V1.

Patch set tested by setting /proc/sys/kernel/kptr_restrict and inserting the following module

#include <linux/init.h>
#include <linux/module.h>

#define DRIVER_AUTHOR "Tobin C. Harding <me@xxxxxxxx>"
#define DRIVER_DESC "Testing module"

static void test_printk(void)
{
	char *ptr = "";

	pr_alert("printing with p: %p\n", ptr);
	pr_alert("printing with pK: %pK\n", ptr);
	pr_alert("printing with pP: %pP\n", ptr);

	pr_alert("printing with pa: %pa\n", ptr);
	pr_alert("printing with pad: %pad\n", ptr);
	pr_alert("printing with pap: %pap\n", ptr);

	pr_alert("printing with paP: %paP\n", ptr);
	pr_alert("printing with padP: %padP\n", ptr);
	pr_alert("printing with papP: %papP\n", ptr);

	pr_alert("printing with pr: %pr\n", ptr);
	pr_alert("printing with pR: %pR\n", ptr);
}

static int hello_init(void)
{
	pr_alert("Hello, world\n");

	test_printk();

	return 0;
}
module_init(hello_init);

static void hello_exit(void)
{
	pr_alert("Goodbye, world\n");
}
module_exit(hello_exit);

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_LICENSE("GPL");