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Date: Wed, 1 Nov 2017 14:36:58 -0700
From: Laura Abbott <labbott@...hat.com>
To: Kees Cook <keescook@...omium.org>
Cc: Laura Abbott <labbott@...hat.com>,
linux-kernel@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Subject: [PATCH] lkdtm: Add tests for put_user/get_user
{get,put}_user are designed to be 'safe' access and
verify the address passed in whereas __{get,put}_user are
supposed to be 'unsafe'. Add a test to verify this behavior.
Signed-off-by: Laura Abbott <labbott@...hat.com>
---
Inspired by the paranoid __{get,put}_user checks for arm64.
---
drivers/misc/lkdtm.h | 2 +
drivers/misc/lkdtm_core.c | 2 +
drivers/misc/lkdtm_usercopy.c | 107 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 111 insertions(+)
diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h
index bfb6c45b6130..c80236198c96 100644
--- a/drivers/misc/lkdtm.h
+++ b/drivers/misc/lkdtm.h
@@ -81,5 +81,7 @@ void lkdtm_USERCOPY_STACK_FRAME_TO(void);
void lkdtm_USERCOPY_STACK_FRAME_FROM(void);
void lkdtm_USERCOPY_STACK_BEYOND(void);
void lkdtm_USERCOPY_KERNEL(void);
+void lkdtm_PUT_USER(void);
+void lkdtm_GET_USER(void);
#endif
diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
index 981b3ef71e47..f0a99ccc2a5a 100644
--- a/drivers/misc/lkdtm_core.c
+++ b/drivers/misc/lkdtm_core.c
@@ -251,6 +251,8 @@ struct crashtype crashtypes[] = {
CRASHTYPE(USERCOPY_STACK_FRAME_FROM),
CRASHTYPE(USERCOPY_STACK_BEYOND),
CRASHTYPE(USERCOPY_KERNEL),
+ CRASHTYPE(PUT_USER),
+ CRASHTYPE(GET_USER),
};
diff --git a/drivers/misc/lkdtm_usercopy.c b/drivers/misc/lkdtm_usercopy.c
index df6ac985fbb5..3a95a85cafdb 100644
--- a/drivers/misc/lkdtm_usercopy.c
+++ b/drivers/misc/lkdtm_usercopy.c
@@ -310,6 +310,113 @@ void lkdtm_USERCOPY_KERNEL(void)
vm_munmap(user_addr, PAGE_SIZE);
}
+void lkdtm_PUT_USER(void)
+{
+ unsigned long user_addr;
+ void *kbuf;
+
+ kbuf = kmalloc(cache_size, GFP_KERNEL);
+ if (!kbuf) {
+ pr_warn("failed to allocate kernel buffer\n");
+ return;
+ }
+
+ user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
+ PROT_READ | PROT_WRITE | PROT_EXEC,
+ MAP_ANONYMOUS | MAP_PRIVATE, 0);
+ if (user_addr >= TASK_SIZE) {
+ pr_warn("Failed to allocate user memory\n");
+ goto free_kernel;
+ }
+
+ pr_info("attempting valid put_user\n");
+ if (put_user(0x1234567, (unsigned long __user *)user_addr)) {
+ pr_warn("put_user failed unexpectedly?!\n");
+ goto free_user;
+ }
+
+
+ pr_info("attempting valid __put_user\n");
+ if (__put_user(0x1234567, (unsigned long __user *)user_addr)) {
+ pr_warn("__put_user failed unexpectedly?!\n");
+ goto free_user;
+ }
+
+ pr_info("attempting invalid put_user which should fail");
+ if (put_user(0x1234567, (unsigned long *)kbuf)) {
+ pr_warn("put_user failed correctly\n");
+ } else {
+ pr_warn("put_user succeeded unexpectedly\n");
+ goto free_user;
+ }
+
+
+ pr_info("attempting invalid __put_user which should succeed\n");
+ if (__put_user(0x1234567, (unsigned long *)kbuf)) {
+ pr_warn("__put_user failed unexpectedly\n");
+ } else {
+ pr_warn("__put_user succeeded\n");
+ }
+
+free_user:
+ vm_munmap(user_addr, PAGE_SIZE);
+free_kernel:
+ kfree(kbuf);
+}
+
+void lkdtm_GET_USER(void)
+{
+ unsigned long user_addr;
+ unsigned long a;
+ void *kbuf;
+
+ kbuf = kmalloc(cache_size, GFP_KERNEL);
+ if (!kbuf) {
+ pr_warn("failed to allocate kernel buffer\n");
+ return;
+ }
+
+ user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
+ PROT_READ | PROT_WRITE | PROT_EXEC,
+ MAP_ANONYMOUS | MAP_PRIVATE, 0);
+ if (user_addr >= TASK_SIZE) {
+ pr_warn("Failed to allocate user memory\n");
+ goto free_kernel;
+ }
+
+ pr_info("attempting valid get_user\n");
+ if (get_user(a, (unsigned long __user *)user_addr)) {
+ pr_warn("get_user failed unexpectedly?!\n");
+ goto free_user;
+ }
+
+ pr_info("attempting valid __get_user\n");
+ if (__get_user(a, (unsigned long __user *)user_addr)) {
+ pr_warn("__get_user failed unexpectedly?!\n");
+ goto free_user;
+ }
+
+ pr_info("attempting an invalid get_user which should fail\n");
+ if (get_user(a, (unsigned long *)kbuf)) {
+ pr_warn("get_user failed correctly\n");
+ } else {
+ pr_warn("get_user succeeded unexpectedly\n");
+ goto free_user;
+ }
+
+ pr_info("attempting an invalid __get_user which should succeed\n");
+ if (__get_user(a, (unsigned long *)kbuf)) {
+ pr_warn("get_user failed unexpectedly\n");
+ } else {
+ pr_warn("get_user succeeded\n");
+ }
+
+free_user:
+ vm_munmap(user_addr, PAGE_SIZE);
+free_kernel:
+ kfree(kbuf);
+}
+
void __init lkdtm_usercopy_init(void)
{
/* Prepare cache that lacks SLAB_USERCOPY flag. */
--
2.13.5
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