linux/lib/livepatch/test_klp_shadow_vars.c

302 lines
7.6 KiB
C

// 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)
{
int **sv;
sv = 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(sv));
return sv;
}
static void *shadow_alloc(void *obj, unsigned long id, size_t size,
gfp_t gfp_flags, klp_shadow_ctor_t ctor,
void *ctor_data)
{
int **var = ctor_data;
int **sv;
sv = klp_shadow_alloc(obj, id, size, gfp_flags, ctor, var);
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(*var), ptr_id(sv));
return sv;
}
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)
{
int **var = ctor_data;
int **sv;
sv = klp_shadow_get_or_alloc(obj, id, size, gfp_flags, ctor, var);
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(*var), ptr_id(sv));
return sv;
}
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 **sv = shadow_data;
int **var = ctor_data;
if (!var)
return -EINVAL;
*sv = *var;
pr_info("%s: PTR%d -> PTR%d\n", __func__, ptr_id(sv), ptr_id(*var));
return 0;
}
/*
* With more than one item to free in the list, order is not determined and
* shadow_dtor will not be passed to shadow_free_all() which would make the
* test fail. (see pass 6)
*/
static void shadow_dtor(void *obj, void *shadow_data)
{
int **sv = shadow_data;
pr_info("%s(obj=PTR%d, shadow_data=PTR%d)\n",
__func__, ptr_id(obj), ptr_id(sv));
}
/* number of objects we simulate that need shadow vars */
#define NUM_OBJS 3
/* dynamically created obj fields have the following shadow var id values */
#define SV_ID1 0x1234
#define SV_ID2 0x1235
/*
* The main test case adds/removes new fields (shadow var) to each of these
* test structure instances. The last group of fields in the struct represent
* the idea that shadow variables may be added and removed to and from the
* struct during execution.
*/
struct test_object {
/* add anything here below and avoid to define an empty struct */
struct shadow_ptr sp;
/* these represent shadow vars added and removed with SV_ID{1,2} */
/* char nfield1; */
/* int nfield2; */
};
static int test_klp_shadow_vars_init(void)
{
struct test_object objs[NUM_OBJS];
char nfields1[NUM_OBJS], *pnfields1[NUM_OBJS], **sv1[NUM_OBJS];
char *pndup[NUM_OBJS];
int nfields2[NUM_OBJS], *pnfields2[NUM_OBJS], **sv2[NUM_OBJS];
void **sv;
int ret;
int i;
ptr_id(NULL);
/*
* With an empty shadow variable hash table, expect not to find
* any matches.
*/
sv = shadow_get(&objs[0], SV_ID1);
if (!sv)
pr_info(" got expected NULL result\n");
/* pass 1: init & alloc a char+int pair of svars for each objs */
for (i = 0; i < NUM_OBJS; i++) {
pnfields1[i] = &nfields1[i];
ptr_id(pnfields1[i]);
if (i % 2) {
sv1[i] = shadow_alloc(&objs[i], SV_ID1,
sizeof(pnfields1[i]), GFP_KERNEL,
shadow_ctor, &pnfields1[i]);
} else {
sv1[i] = shadow_get_or_alloc(&objs[i], SV_ID1,
sizeof(pnfields1[i]), GFP_KERNEL,
shadow_ctor, &pnfields1[i]);
}
if (!sv1[i]) {
ret = -ENOMEM;
goto out;
}
pnfields2[i] = &nfields2[i];
ptr_id(pnfields2[i]);
sv2[i] = shadow_alloc(&objs[i], SV_ID2, sizeof(pnfields2[i]),
GFP_KERNEL, shadow_ctor, &pnfields2[i]);
if (!sv2[i]) {
ret = -ENOMEM;
goto out;
}
}
/* pass 2: verify we find allocated svars and where they point to */
for (i = 0; i < NUM_OBJS; i++) {
/* check the "char" svar for all objects */
sv = shadow_get(&objs[i], SV_ID1);
if (!sv) {
ret = -EINVAL;
goto out;
}
if ((char **)sv == sv1[i] && *sv1[i] == pnfields1[i])
pr_info(" got expected PTR%d -> PTR%d result\n",
ptr_id(sv1[i]), ptr_id(*sv1[i]));
/* check the "int" svar for all objects */
sv = shadow_get(&objs[i], SV_ID2);
if (!sv) {
ret = -EINVAL;
goto out;
}
if ((int **)sv == sv2[i] && *sv2[i] == pnfields2[i])
pr_info(" got expected PTR%d -> PTR%d result\n",
ptr_id(sv2[i]), ptr_id(*sv2[i]));
}
/* pass 3: verify that 'get_or_alloc' returns already allocated svars */
for (i = 0; i < NUM_OBJS; i++) {
pndup[i] = &nfields1[i];
ptr_id(pndup[i]);
sv = shadow_get_or_alloc(&objs[i], SV_ID1, sizeof(pndup[i]),
GFP_KERNEL, shadow_ctor, &pndup[i]);
if (!sv) {
ret = -EINVAL;
goto out;
}
if ((char **)sv == sv1[i] && *sv1[i] == pnfields1[i])
pr_info(" got expected PTR%d -> PTR%d result\n",
ptr_id(sv1[i]), ptr_id(*sv1[i]));
}
/* pass 4: free <objs[*], SV_ID1> pairs of svars, verify removal */
for (i = 0; i < NUM_OBJS; i++) {
shadow_free(&objs[i], SV_ID1, shadow_dtor); /* 'char' pairs */
sv = shadow_get(&objs[i], SV_ID1);
if (!sv)
pr_info(" got expected NULL result\n");
}
/* pass 5: check we still find <objs[*], SV_ID2> svar pairs */
for (i = 0; i < NUM_OBJS; i++) {
sv = shadow_get(&objs[i], SV_ID2); /* 'int' pairs */
if (!sv) {
ret = -EINVAL;
goto out;
}
if ((int **)sv == sv2[i] && *sv2[i] == pnfields2[i])
pr_info(" got expected PTR%d -> PTR%d result\n",
ptr_id(sv2[i]), ptr_id(*sv2[i]));
}
/* pass 6: free all the <objs[*], SV_ID2> svar pairs too. */
shadow_free_all(SV_ID2, NULL); /* 'int' pairs */
for (i = 0; i < NUM_OBJS; i++) {
sv = shadow_get(&objs[i], SV_ID2);
if (!sv)
pr_info(" got expected NULL result\n");
}
free_ptr_list();
return 0;
out:
shadow_free_all(SV_ID1, NULL); /* 'char' pairs */
shadow_free_all(SV_ID2, NULL); /* 'int' pairs */
free_ptr_list();
return ret;
}
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");