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lkdtm: split heap corruption tests to separate file

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This splits the *_AFTER_FREE and related tests into the new lkdtm_heap.c
file to help separate things better for readability.

Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook 2016-06-26 21:45:23 -07:00
parent 0d9eb29b13
commit ffc514f3fc
4 changed files with 164 additions and 114 deletions
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1
drivers/misc/Makefile
View file

@ -59,6 +59,7 @@ obj-$(CONFIG_CXL_BASE) += cxl/
obj-$(CONFIG_PANEL) += panel.o
lkdtm-$(CONFIG_LKDTM) += lkdtm_core.o
lkdtm-$(CONFIG_LKDTM) += lkdtm_heap.o
lkdtm-$(CONFIG_LKDTM) += lkdtm_perms.o
lkdtm-$(CONFIG_LKDTM) += lkdtm_rodata_objcopy.o
lkdtm-$(CONFIG_LKDTM) += lkdtm_usercopy.o

7
drivers/misc/lkdtm.h
View file

@ -1,6 +1,13 @@
#ifndef __LKDTM_H
#define __LKDTM_H
/* lkdtm_heap.c */
void lkdtm_OVERWRITE_ALLOCATION(void);
void lkdtm_WRITE_AFTER_FREE(void);
void lkdtm_READ_AFTER_FREE(void);
void lkdtm_WRITE_BUDDY_AFTER_FREE(void);
void lkdtm_READ_BUDDY_AFTER_FREE(void);
/* lkdtm_perms.c */
void __init lkdtm_perms_init(void);
void lkdtm_WRITE_RO(void);

124
drivers/misc/lkdtm_core.c
View file

@ -384,125 +384,21 @@ static void lkdtm_do_action(enum ctype which)
*p = val;
break;
}
case CT_OVERWRITE_ALLOCATION: {
size_t len = 1020;
u32 *data = kmalloc(len, GFP_KERNEL);
data[1024 / sizeof(u32)] = 0x12345678;
kfree(data);
case CT_OVERWRITE_ALLOCATION:
lkdtm_OVERWRITE_ALLOCATION();
break;
}
case CT_WRITE_AFTER_FREE: {
int *base, *again;
size_t len = 1024;
/*
* The slub allocator uses the first word to store the free
* pointer in some configurations. Use the middle of the
* allocation to avoid running into the freelist
*/
size_t offset = (len / sizeof(*base)) / 2;
base = kmalloc(len, GFP_KERNEL);
pr_info("Allocated memory %p-%p\n", base, &base[offset * 2]);
pr_info("Attempting bad write to freed memory at %p\n",
&base[offset]);
kfree(base);
base[offset] = 0x0abcdef0;
/* Attempt to notice the overwrite. */
again = kmalloc(len, GFP_KERNEL);
kfree(again);
if (again != base)
pr_info("Hmm, didn't get the same memory range.\n");
case CT_WRITE_AFTER_FREE:
lkdtm_WRITE_AFTER_FREE();
break;
}
case CT_READ_AFTER_FREE: {
int *base, *val, saw;
size_t len = 1024;
/*
* The slub allocator uses the first word to store the free
* pointer in some configurations. Use the middle of the
* allocation to avoid running into the freelist
*/
size_t offset = (len / sizeof(*base)) / 2;
base = kmalloc(len, GFP_KERNEL);
if (!base)
break;
val = kmalloc(len, GFP_KERNEL);
if (!val) {
kfree(base);
break;
}
*val = 0x12345678;
base[offset] = *val;
pr_info("Value in memory before free: %x\n", base[offset]);
kfree(base);
pr_info("Attempting bad read from freed memory\n");
saw = base[offset];
if (saw != *val) {
/* Good! Poisoning happened, so declare a win. */
pr_info("Memory correctly poisoned (%x)\n", saw);
BUG();
}
pr_info("Memory was not poisoned\n");
kfree(val);
case CT_READ_AFTER_FREE:
lkdtm_READ_AFTER_FREE();
break;
}
case CT_WRITE_BUDDY_AFTER_FREE: {
unsigned long p = __get_free_page(GFP_KERNEL);
if (!p)
break;
pr_info("Writing to the buddy page before free\n");
memset((void *)p, 0x3, PAGE_SIZE);
free_page(p);
schedule();
pr_info("Attempting bad write to the buddy page after free\n");
memset((void *)p, 0x78, PAGE_SIZE);
/* Attempt to notice the overwrite. */
p = __get_free_page(GFP_KERNEL);
free_page(p);
schedule();
case CT_WRITE_BUDDY_AFTER_FREE:
lkdtm_WRITE_BUDDY_AFTER_FREE();
break;
}
case CT_READ_BUDDY_AFTER_FREE: {
unsigned long p = __get_free_page(GFP_KERNEL);
int saw, *val;
int *base;
if (!p)
break;
val = kmalloc(1024, GFP_KERNEL);
if (!val) {
free_page(p);
break;
}
base = (int *)p;
*val = 0x12345678;
base[0] = *val;
pr_info("Value in memory before free: %x\n", base[0]);
free_page(p);
pr_info("Attempting to read from freed memory\n");
saw = base[0];
if (saw != *val) {
/* Good! Poisoning happened, so declare a win. */
pr_info("Memory correctly poisoned (%x)\n", saw);
BUG();
}
pr_info("Buddy page was not poisoned\n");
kfree(val);
case CT_READ_BUDDY_AFTER_FREE:
lkdtm_READ_BUDDY_AFTER_FREE();
break;
}
case CT_SOFTLOCKUP:
preempt_disable();
for (;;)

146
drivers/misc/lkdtm_heap.c Normal file
View file

@ -0,0 +1,146 @@
/*
* This is for all the tests relating directly to heap memory, including
* page allocation and slab allocations.
*/
#define pr_fmt(fmt) "lkdtm: " fmt
#include <linux/kernel.h>
#include <linux/slab.h>
#include "lkdtm.h"
/*
* This tries to stay within the next largest power-of-2 kmalloc cache
* to avoid actually overwriting anything important if it's not detected
* correctly.
*/
void lkdtm_OVERWRITE_ALLOCATION(void)
{
size_t len = 1020;
u32 *data = kmalloc(len, GFP_KERNEL);
data[1024 / sizeof(u32)] = 0x12345678;
kfree(data);
}
void lkdtm_WRITE_AFTER_FREE(void)
{
int *base, *again;
size_t len = 1024;
/*
* The slub allocator uses the first word to store the free
* pointer in some configurations. Use the middle of the
* allocation to avoid running into the freelist
*/
size_t offset = (len / sizeof(*base)) / 2;
base = kmalloc(len, GFP_KERNEL);
pr_info("Allocated memory %p-%p\n", base, &base[offset * 2]);
pr_info("Attempting bad write to freed memory at %p\n",
&base[offset]);
kfree(base);
base[offset] = 0x0abcdef0;
/* Attempt to notice the overwrite. */
again = kmalloc(len, GFP_KERNEL);
kfree(again);
if (again != base)
pr_info("Hmm, didn't get the same memory range.\n");
}
void lkdtm_READ_AFTER_FREE(void)
{
int *base, *val, saw;
size_t len = 1024;
/*
* The slub allocator uses the first word to store the free
* pointer in some configurations. Use the middle of the
* allocation to avoid running into the freelist
*/
size_t offset = (len / sizeof(*base)) / 2;
base = kmalloc(len, GFP_KERNEL);
if (!base) {
pr_info("Unable to allocate base memory.\n");
return;
}
val = kmalloc(len, GFP_KERNEL);
if (!val) {
pr_info("Unable to allocate val memory.\n");
kfree(base);
return;
}
*val = 0x12345678;
base[offset] = *val;
pr_info("Value in memory before free: %x\n", base[offset]);
kfree(base);
pr_info("Attempting bad read from freed memory\n");
saw = base[offset];
if (saw != *val) {
/* Good! Poisoning happened, so declare a win. */
pr_info("Memory correctly poisoned (%x)\n", saw);
BUG();
}
pr_info("Memory was not poisoned\n");
kfree(val);
}
void lkdtm_WRITE_BUDDY_AFTER_FREE(void)
{
unsigned long p = __get_free_page(GFP_KERNEL);
if (!p) {
pr_info("Unable to allocate free page\n");
return;
}
pr_info("Writing to the buddy page before free\n");
memset((void *)p, 0x3, PAGE_SIZE);
free_page(p);
schedule();
pr_info("Attempting bad write to the buddy page after free\n");
memset((void *)p, 0x78, PAGE_SIZE);
/* Attempt to notice the overwrite. */
p = __get_free_page(GFP_KERNEL);
free_page(p);
schedule();
}
void lkdtm_READ_BUDDY_AFTER_FREE(void)
{
unsigned long p = __get_free_page(GFP_KERNEL);
int saw, *val;
int *base;
if (!p) {
pr_info("Unable to allocate free page\n");
return;
}
val = kmalloc(1024, GFP_KERNEL);
if (!val) {
pr_info("Unable to allocate val memory.\n");
free_page(p);
return;
}
base = (int *)p;
*val = 0x12345678;
base[0] = *val;
pr_info("Value in memory before free: %x\n", base[0]);
free_page(p);
pr_info("Attempting to read from freed memory\n");
saw = base[0];
if (saw != *val) {
/* Good! Poisoning happened, so declare a win. */
pr_info("Memory correctly poisoned (%x)\n", saw);
BUG();
}
pr_info("Buddy page was not poisoned\n");
kfree(val);
}