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// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2018 Joe Lawrence <joe.lawrence@redhat.com>
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/livepatch.h>
#include <linux/slab.h>
/*
* Keep a small list of pointers so that we can print address-agnostic
* pointer values. Use a rolling integer count to differentiate the values.
* Ironically we could have used the shadow variable API to do this, but
* let's not lean too heavily on the very code we're testing.
*/
static LIST_HEAD(ptr_list);
struct shadow_ptr {
void *ptr;
int id;
struct list_head list;
};
static void free_ptr_list(void)
{
struct shadow_ptr *sp, *tmp_sp;
list_for_each_entry_safe(sp, tmp_sp, &ptr_list, list) {
list_del(&sp->list);
kfree(sp);
}
}
static int ptr_id(void *ptr)
{
struct shadow_ptr *sp;
static int count;
list_for_each_entry(sp, &ptr_list, list) {
if (sp->ptr == ptr)
return sp->id;
}
sp = kmalloc(sizeof(*sp), GFP_ATOMIC);
if (!sp)
return -ENOMEM;
sp->ptr = ptr;
sp->id = count++;
list_add(&sp->list, &ptr_list);
return sp->id;
}
/*
* Shadow variable wrapper functions that echo the function and arguments
* to the kernel log for testing verification. Don't display raw pointers,
* but use the ptr_id() value instead.
*/
static void *shadow_get(void *obj, unsigned long id)
{
void *ret = klp_shadow_get(obj, id);
pr_info("klp_%s(obj=PTR%d, id=0x%lx) = PTR%d\n",
__func__, ptr_id(obj), id, ptr_id(ret));
return ret;
}
static void *shadow_alloc(void *obj, unsigned long id, size_t size,
gfp_t gfp_flags, klp_shadow_ctor_t ctor,
void *ctor_data)
{
void *ret = klp_shadow_alloc(obj, id, size, gfp_flags, ctor,
ctor_data);
pr_info("klp_%s(obj=PTR%d, id=0x%lx, size=%zx, gfp_flags=%pGg), ctor=PTR%d, ctor_data=PTR%d = PTR%d\n",
__func__, ptr_id(obj), id, size, &gfp_flags, ptr_id(ctor),
ptr_id(ctor_data), ptr_id(ret));
return ret;
}
static void *shadow_get_or_alloc(void *obj, unsigned long id, size_t size,
gfp_t gfp_flags, klp_shadow_ctor_t ctor,
void *ctor_data)
{
void *ret = klp_shadow_get_or_alloc(obj, id, size, gfp_flags, ctor,
ctor_data);
pr_info("klp_%s(obj=PTR%d, id=0x%lx, size=%zx, gfp_flags=%pGg), ctor=PTR%d, ctor_data=PTR%d = PTR%d\n",
__func__, ptr_id(obj), id, size, &gfp_flags, ptr_id(ctor),
ptr_id(ctor_data), ptr_id(ret));
return ret;
}
static void shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor)
{
klp_shadow_free(obj, id, dtor);
pr_info("klp_%s(obj=PTR%d, id=0x%lx, dtor=PTR%d)\n",
__func__, ptr_id(obj), id, ptr_id(dtor));
}
static void shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor)
{
klp_shadow_free_all(id, dtor);
pr_info("klp_%s(id=0x%lx, dtor=PTR%d)\n",
__func__, id, ptr_id(dtor));
}
/* Shadow variable constructor - remember simple pointer data */
static int shadow_ctor(void *obj, void *shadow_data, void *ctor_data)
{
int **shadow_int = shadow_data;
*shadow_int = ctor_data;
pr_info("%s: PTR%d -> PTR%d\n",
__func__, ptr_id(shadow_int), ptr_id(ctor_data));
return 0;
}
static void shadow_dtor(void *obj, void *shadow_data)
{
pr_info("%s(obj=PTR%d, shadow_data=PTR%d)\n",
__func__, ptr_id(obj), ptr_id(shadow_data));
}
static int test_klp_shadow_vars_init(void)
{
void *obj = THIS_MODULE;
int id = 0x1234;
size_t size = sizeof(int *);
gfp_t gfp_flags = GFP_KERNEL;
int var1, var2, var3, var4;
int **sv1, **sv2, **sv3, **sv4;
void *ret;
ptr_id(NULL);
ptr_id(&var1);
ptr_id(&var2);
ptr_id(&var3);
ptr_id(&var4);
/*
* With an empty shadow variable hash table, expect not to find
* any matches.
*/
ret = shadow_get(obj, id);
if (!ret)
pr_info(" got expected NULL result\n");
/*
* Allocate a few shadow variables with different <obj> and <id>.
*/
sv1 = shadow_alloc(obj, id, size, gfp_flags, shadow_ctor, &var1);
sv2 = shadow_alloc(obj + 1, id, size, gfp_flags, shadow_ctor, &var2);
sv3 = shadow_alloc(obj, id + 1, size, gfp_flags, shadow_ctor, &var3);
/*
* Verify we can find our new shadow variables and that they point
* to expected data.
*/
ret = shadow_get(obj, id);
if (ret == sv1 && *sv1 == &var1)
pr_info(" got expected PTR%d -> PTR%d result\n",
ptr_id(sv1), ptr_id(*sv1));
ret = shadow_get(obj + 1, id);
if (ret == sv2 && *sv2 == &var2)
pr_info(" got expected PTR%d -> PTR%d result\n",
ptr_id(sv2), ptr_id(*sv2));
ret = shadow_get(obj, id + 1);
if (ret == sv3 && *sv3 == &var3)
pr_info(" got expected PTR%d -> PTR%d result\n",
ptr_id(sv3), ptr_id(*sv3));
/*
* Allocate or get a few more, this time with the same <obj>, <id>.
* The second invocation should return the same shadow var.
*/
sv4 = shadow_get_or_alloc(obj + 2, id, size, gfp_flags, shadow_ctor, &var4);
ret = shadow_get_or_alloc(obj + 2, id, size, gfp_flags, shadow_ctor, &var4);
if (ret == sv4 && *sv4 == &var4)
pr_info(" got expected PTR%d -> PTR%d result\n",
ptr_id(sv4), ptr_id(*sv4));
/*
* Free the <obj=*, id> shadow variables and check that we can no
* longer find them.
*/
shadow_free(obj, id, shadow_dtor); /* sv1 */
ret = shadow_get(obj, id);
if (!ret)
pr_info(" got expected NULL result\n");
shadow_free(obj + 1, id, shadow_dtor); /* sv2 */
ret = shadow_get(obj + 1, id);
if (!ret)
pr_info(" got expected NULL result\n");
shadow_free(obj + 2, id, shadow_dtor); /* sv4 */
ret = shadow_get(obj + 2, id);
if (!ret)
pr_info(" got expected NULL result\n");
/*
* We should still find an <id+1> variable.
*/
ret = shadow_get(obj, id + 1);
if (ret == sv3 && *sv3 == &var3)
pr_info(" got expected PTR%d -> PTR%d result\n",
ptr_id(sv3), ptr_id(*sv3));
/*
* Free all the <id+1> variables, too.
*/
shadow_free_all(id + 1, shadow_dtor); /* sv3 */
ret = shadow_get(obj, id);
if (!ret)
pr_info(" shadow_get() got expected NULL result\n");
free_ptr_list();
return 0;
}
static void test_klp_shadow_vars_exit(void)
{
}
module_init(test_klp_shadow_vars_init);
module_exit(test_klp_shadow_vars_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
MODULE_DESCRIPTION("Livepatch test: shadow variables");
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