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Message-ID: <20180228200620.30026-7-igor.stoppa@huawei.com>
Date: Wed, 28 Feb 2018 22:06:19 +0200
From: Igor Stoppa <igor.stoppa@...wei.com>
To: <david@...morbit.com>, <willy@...radead.org>, <keescook@...omium.org>,
<mhocko@...nel.org>
CC: <labbott@...hat.com>, <linux-security-module@...r.kernel.org>,
<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
<kernel-hardening@...ts.openwall.com>, Igor Stoppa <igor.stoppa@...wei.com>
Subject: [PATCH 6/7] lkdtm: crash on overwriting protected pmalloc var
Verify that pmalloc read-only protection is in place: trying to
overwrite a protected variable will crash the kernel.
Signed-off-by: Igor Stoppa <igor.stoppa@...wei.com>
---
drivers/misc/lkdtm.h | 1 +
drivers/misc/lkdtm_core.c | 3 +++
drivers/misc/lkdtm_perms.c | 28 ++++++++++++++++++++++++++++
3 files changed, 32 insertions(+)
diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h
index 9e513dcfd809..dcda3ae76ceb 100644
--- a/drivers/misc/lkdtm.h
+++ b/drivers/misc/lkdtm.h
@@ -38,6 +38,7 @@ void lkdtm_READ_BUDDY_AFTER_FREE(void);
void __init lkdtm_perms_init(void);
void lkdtm_WRITE_RO(void);
void lkdtm_WRITE_RO_AFTER_INIT(void);
+void lkdtm_WRITE_RO_PMALLOC(void);
void lkdtm_WRITE_KERN(void);
void lkdtm_EXEC_DATA(void);
void lkdtm_EXEC_STACK(void);
diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
index 2154d1bfd18b..c9fd42bda6ee 100644
--- a/drivers/misc/lkdtm_core.c
+++ b/drivers/misc/lkdtm_core.c
@@ -155,6 +155,9 @@ static const struct crashtype crashtypes[] = {
CRASHTYPE(ACCESS_USERSPACE),
CRASHTYPE(WRITE_RO),
CRASHTYPE(WRITE_RO_AFTER_INIT),
+#ifdef CONFIG_PROTECTABLE_MEMORY
+ CRASHTYPE(WRITE_RO_PMALLOC),
+#endif
CRASHTYPE(WRITE_KERN),
CRASHTYPE(REFCOUNT_INC_OVERFLOW),
CRASHTYPE(REFCOUNT_ADD_OVERFLOW),
diff --git a/drivers/misc/lkdtm_perms.c b/drivers/misc/lkdtm_perms.c
index 53b85c9d16b8..0ac9023fd2b0 100644
--- a/drivers/misc/lkdtm_perms.c
+++ b/drivers/misc/lkdtm_perms.c
@@ -9,6 +9,7 @@
#include <linux/vmalloc.h>
#include <linux/mman.h>
#include <linux/uaccess.h>
+#include <linux/pmalloc.h>
#include <asm/cacheflush.h>
/* Whether or not to fill the target memory area with do_nothing(). */
@@ -104,6 +105,33 @@ void lkdtm_WRITE_RO_AFTER_INIT(void)
*ptr ^= 0xabcd1234;
}
+#ifdef CONFIG_PROTECTABLE_MEMORY
+void lkdtm_WRITE_RO_PMALLOC(void)
+{
+ struct gen_pool *pool;
+ int *i;
+
+ pool = pmalloc_create_pool("pool", 0);
+ if (unlikely(!pool)) {
+ pr_info("Failed preparing pool for pmalloc test.");
+ return;
+ }
+
+ i = (int *)pmalloc(pool, sizeof(int), GFP_KERNEL);
+ if (unlikely(!i)) {
+ pr_info("Failed allocating memory for pmalloc test.");
+ pmalloc_destroy_pool(pool);
+ return;
+ }
+
+ *i = INT_MAX;
+ pmalloc_protect_pool(pool);
+
+ pr_info("attempting bad pmalloc write at %p\n", i);
+ *i = 0;
+}
+#endif
+
void lkdtm_WRITE_KERN(void)
{
size_t size;
--
2.14.1
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