From: Kees Cook <keescook@chromium.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Kees Cook <keescook@chromium.org>,
Elena Reshetova <elena.reshetova@intel.com>,
x86@kernel.org, Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Potapenko <glider@google.com>,
Alexander Popov <alex.popov@linux.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Jann Horn <jannh@google.com>,
kernel-hardening@lists.openwall.com,
linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: [PATCH v4 4/5] x86/entry: Enable random_kstack_offset support
Date: Mon, 22 Jun 2020 12:31:45 -0700 [thread overview]
Message-ID: <20200622193146.2985288-5-keescook@chromium.org> (raw)
In-Reply-To: <20200622193146.2985288-1-keescook@chromium.org>
Allow for a randomized stack offset on a per-syscall basis, with roughly
5 bits of entropy.
Signed-off-by: Kees Cook <keescook@chromium.org>
---
arch/x86/Kconfig | 1 +
arch/x86/entry/common.c | 11 +++++++++++
2 files changed, 12 insertions(+)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 6a0cc524882d..57c2a458150e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -156,6 +156,7 @@ config X86
select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
select HAVE_ARCH_VMAP_STACK if X86_64
+ select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
select HAVE_ARCH_WITHIN_STACK_FRAMES
select HAVE_ASM_MODVERSIONS
select HAVE_CMPXCHG_DOUBLE
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index bd3f14175193..681125bbf09a 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -26,6 +26,7 @@
#include <linux/livepatch.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>
+#include <linux/randomize_kstack.h>
#ifdef CONFIG_XEN_PV
#include <xen/xen-ops.h>
@@ -240,6 +241,13 @@ static void __prepare_exit_to_usermode(struct pt_regs *regs)
lockdep_assert_irqs_disabled();
lockdep_sys_exit();
+ /*
+ * x86_64 stack alignment means 3 bits are ignored, so keep
+ * the top 5 bits. x86_32 needs only 2 bits of alignment, so
+ * the top 6 bits will be used.
+ */
+ choose_random_kstack_offset(rdtsc() & 0xFF);
+
cached_flags = READ_ONCE(ti->flags);
if (unlikely(cached_flags & EXIT_TO_USERMODE_LOOP_FLAGS))
@@ -346,6 +354,7 @@ __visible noinstr void do_syscall_64(unsigned long nr, struct pt_regs *regs)
{
struct thread_info *ti;
+ add_random_kstack_offset();
enter_from_user_mode();
instrumentation_begin();
@@ -409,6 +418,7 @@ static void do_syscall_32_irqs_on(struct pt_regs *regs)
/* Handles int $0x80 */
__visible noinstr void do_int80_syscall_32(struct pt_regs *regs)
{
+ add_random_kstack_offset();
enter_from_user_mode();
instrumentation_begin();
@@ -467,6 +477,7 @@ __visible noinstr long do_fast_syscall_32(struct pt_regs *regs)
*/
regs->ip = landing_pad;
+ add_random_kstack_offset();
enter_from_user_mode();
instrumentation_begin();
--
2.25.1
next prev parent reply other threads:[~2020-06-22 19:32 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-22 19:31 [PATCH v4 0/5] Optionally randomize kernel stack offset each syscall Kees Cook
2020-06-22 19:31 ` [PATCH v4 1/5] jump_label: Provide CONFIG-driven build state defaults Kees Cook
2020-06-22 19:31 ` [PATCH v4 2/5] init_on_alloc: Unpessimize default-on builds Kees Cook
2020-06-22 19:31 ` [PATCH v4 3/5] stack: Optionally randomize kernel stack offset each syscall Kees Cook
2020-06-22 19:40 ` Randy Dunlap
2020-06-22 21:26 ` Kees Cook
2020-06-22 20:07 ` Jann Horn
2020-06-22 21:30 ` Kees Cook
2020-06-22 21:42 ` Jann Horn
2020-06-22 22:04 ` Kees Cook
2020-06-22 22:56 ` Arvind Sankar
2020-06-22 23:07 ` Kees Cook
2020-06-23 0:05 ` Arvind Sankar
2020-06-23 0:56 ` Kees Cook
2020-06-23 13:42 ` David Laight
2020-06-23 12:38 ` Alexander Popov
2020-06-22 19:31 ` Kees Cook [this message]
2020-06-22 19:31 ` [PATCH v4 5/5] arm64: entry: Enable random_kstack_offset support Kees Cook
2020-06-23 9:40 ` Mark Rutland
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