* [PATCH v2] lkdtm: add bad USER_DS test
@ 2017-03-24 17:51 Kees Cook
2017-03-31 16:35 ` Kees Cook
0 siblings, 1 reply; 2+ messages in thread
From: Kees Cook @ 2017-03-24 17:51 UTC (permalink / raw)
To: linux-arm-kernel
This adds CORRUPT_USER_DS to check that the get_fs() test on syscall
return (via __VERIFY_PRE_USERMODE_STATE) still sees USER_DS. Since
trying to deal with values other than USER_DS and KERNEL_DS across all
architectures in a safe way is not sensible, this sets KERNEL_DS, but
since that could be extremely dangerous if the protection is not present,
it also raises SIGKILL for current, so that no matter what, the process
will die. A successful test will be visible with a BUG(), like all the
other LKDTM tests.
Signed-off-by: Kees Cook <keescook@chromium.org>
---
drivers/misc/lkdtm.h | 1 +
drivers/misc/lkdtm_bugs.c | 11 +++++++++++
drivers/misc/lkdtm_core.c | 1 +
3 files changed, 13 insertions(+)
diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h
index 67d27be60405..3b4976396ec4 100644
--- a/drivers/misc/lkdtm.h
+++ b/drivers/misc/lkdtm.h
@@ -27,6 +27,7 @@ void lkdtm_REFCOUNT_ZERO_SUB(void);
void lkdtm_REFCOUNT_ZERO_ADD(void);
void lkdtm_CORRUPT_LIST_ADD(void);
void lkdtm_CORRUPT_LIST_DEL(void);
+void lkdtm_CORRUPT_USER_DS(void);
/* lkdtm_heap.c */
void lkdtm_OVERWRITE_ALLOCATION(void);
diff --git a/drivers/misc/lkdtm_bugs.c b/drivers/misc/lkdtm_bugs.c
index e3f4cd8876b5..ed4f4c56c796 100644
--- a/drivers/misc/lkdtm_bugs.c
+++ b/drivers/misc/lkdtm_bugs.c
@@ -8,6 +8,8 @@
#include <linux/list.h>
#include <linux/refcount.h>
#include <linux/sched.h>
+#include <linux/sched/signal.h>
+#include <linux/uaccess.h>
struct lkdtm_list {
struct list_head node;
@@ -279,3 +281,12 @@ void lkdtm_CORRUPT_LIST_DEL(void)
else
pr_err("list_del() corruption not detected!\n");
}
+
+void lkdtm_CORRUPT_USER_DS(void)
+{
+ pr_info("setting bad task size limit\n");
+ set_fs(KERNEL_DS);
+
+ /* Make sure we do not keep running with a KERNEL_DS! */
+ force_sig(SIGKILL, current);
+}
diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
index b9a4cd4a9b68..42d2b8e31e6b 100644
--- a/drivers/misc/lkdtm_core.c
+++ b/drivers/misc/lkdtm_core.c
@@ -199,6 +199,7 @@ struct crashtype crashtypes[] = {
CRASHTYPE(OVERFLOW),
CRASHTYPE(CORRUPT_LIST_ADD),
CRASHTYPE(CORRUPT_LIST_DEL),
+ CRASHTYPE(CORRUPT_USER_DS),
CRASHTYPE(CORRUPT_STACK),
CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE),
CRASHTYPE(OVERWRITE_ALLOCATION),
--
2.7.4
--
Kees Cook
Pixel Security
^ permalink raw reply related [flat|nested] 2+ messages in thread* [PATCH v2] lkdtm: add bad USER_DS test
2017-03-24 17:51 [PATCH v2] lkdtm: add bad USER_DS test Kees Cook
@ 2017-03-31 16:35 ` Kees Cook
0 siblings, 0 replies; 2+ messages in thread
From: Kees Cook @ 2017-03-31 16:35 UTC (permalink / raw)
To: linux-arm-kernel
On Fri, Mar 24, 2017 at 10:51 AM, Kees Cook <keescook@chromium.org> wrote:
> This adds CORRUPT_USER_DS to check that the get_fs() test on syscall
> return (via __VERIFY_PRE_USERMODE_STATE) still sees USER_DS. Since
> trying to deal with values other than USER_DS and KERNEL_DS across all
> architectures in a safe way is not sensible, this sets KERNEL_DS, but
> since that could be extremely dangerous if the protection is not present,
> it also raises SIGKILL for current, so that no matter what, the process
> will die. A successful test will be visible with a BUG(), like all the
> other LKDTM tests.
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
Greg, can you add this to the drivers/misc tree when you get a moment?
Thanks!
-Kees
> ---
> drivers/misc/lkdtm.h | 1 +
> drivers/misc/lkdtm_bugs.c | 11 +++++++++++
> drivers/misc/lkdtm_core.c | 1 +
> 3 files changed, 13 insertions(+)
>
> diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h
> index 67d27be60405..3b4976396ec4 100644
> --- a/drivers/misc/lkdtm.h
> +++ b/drivers/misc/lkdtm.h
> @@ -27,6 +27,7 @@ void lkdtm_REFCOUNT_ZERO_SUB(void);
> void lkdtm_REFCOUNT_ZERO_ADD(void);
> void lkdtm_CORRUPT_LIST_ADD(void);
> void lkdtm_CORRUPT_LIST_DEL(void);
> +void lkdtm_CORRUPT_USER_DS(void);
>
> /* lkdtm_heap.c */
> void lkdtm_OVERWRITE_ALLOCATION(void);
> diff --git a/drivers/misc/lkdtm_bugs.c b/drivers/misc/lkdtm_bugs.c
> index e3f4cd8876b5..ed4f4c56c796 100644
> --- a/drivers/misc/lkdtm_bugs.c
> +++ b/drivers/misc/lkdtm_bugs.c
> @@ -8,6 +8,8 @@
> #include <linux/list.h>
> #include <linux/refcount.h>
> #include <linux/sched.h>
> +#include <linux/sched/signal.h>
> +#include <linux/uaccess.h>
>
> struct lkdtm_list {
> struct list_head node;
> @@ -279,3 +281,12 @@ void lkdtm_CORRUPT_LIST_DEL(void)
> else
> pr_err("list_del() corruption not detected!\n");
> }
> +
> +void lkdtm_CORRUPT_USER_DS(void)
> +{
> + pr_info("setting bad task size limit\n");
> + set_fs(KERNEL_DS);
> +
> + /* Make sure we do not keep running with a KERNEL_DS! */
> + force_sig(SIGKILL, current);
> +}
> diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
> index b9a4cd4a9b68..42d2b8e31e6b 100644
> --- a/drivers/misc/lkdtm_core.c
> +++ b/drivers/misc/lkdtm_core.c
> @@ -199,6 +199,7 @@ struct crashtype crashtypes[] = {
> CRASHTYPE(OVERFLOW),
> CRASHTYPE(CORRUPT_LIST_ADD),
> CRASHTYPE(CORRUPT_LIST_DEL),
> + CRASHTYPE(CORRUPT_USER_DS),
> CRASHTYPE(CORRUPT_STACK),
> CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE),
> CRASHTYPE(OVERWRITE_ALLOCATION),
> --
> 2.7.4
>
>
> --
> Kees Cook
> Pixel Security
--
Kees Cook
Pixel Security
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2017-03-31 16:35 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-03-24 17:51 [PATCH v2] lkdtm: add bad USER_DS test Kees Cook
2017-03-31 16:35 ` Kees Cook
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).