From: Yu-cheng Yu <yu-cheng.yu@intel.com>
To: x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
linux-mm@kvack.org, linux-arch@vger.kernel.org,
linux-api@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Andy Lutomirski <luto@kernel.org>,
Balbir Singh <bsingharora@gmail.com>,
Borislav Petkov <bp@alien8.de>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Eugene Syromiatnikov <esyr@redhat.com>,
Florian Weimer <fweimer@redhat.com>,
"H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
Jonathan Corbet <corbet@lwn.net>,
Kees Cook <keescook@chromium.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Nadav Amit <nadav.amit@gmail.com>,
Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
Peter Zijlstra <peterz@infradead.org>,
Randy Dunlap <rdunlap@infradead.org>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>,
Dave Martin <Dave.Martin@arm.com>,
Weijiang Yang <weijiang.yang@intel.com>,
Pengfei Xu <pengfei.xu@intel.com>,
Haitao Huang <haitao.huang@intel.com>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: [PATCH v23 17/28] mm: Add guard pages around a shadow stack.
Date: Tue, 16 Mar 2021 08:10:43 -0700 [thread overview]
Message-ID: <20210316151054.5405-18-yu-cheng.yu@intel.com> (raw)
In-Reply-To: <20210316151054.5405-1-yu-cheng.yu@intel.com>
INCSSP(Q/D) increments shadow stack pointer and 'pops and discards' the
first and the last elements in the range, effectively touches those memory
areas.
The maximum moving distance by INCSSPQ is 255 * 8 = 2040 bytes and
255 * 4 = 1020 bytes by INCSSPD. Both ranges are far from PAGE_SIZE.
Thus, putting a gap page on both ends of a shadow stack prevents INCSSP,
CALL, and RET from going beyond.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
arch/x86/include/asm/page_64_types.h | 10 ++++++++++
include/linux/mm.h | 24 ++++++++++++++++++++----
2 files changed, 30 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h
index 64297eabad63..23e3d880ce6c 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -115,4 +115,14 @@
#define KERNEL_IMAGE_SIZE (512 * 1024 * 1024)
#endif
+/*
+ * Shadow stack pointer is moved by CALL, RET, and INCSSP(Q/D). INCSSPQ
+ * moves shadow stack pointer up to 255 * 8 = ~2 KB (~1KB for INCSSPD) and
+ * touches the first and the last element in the range, which triggers a
+ * page fault if the range is not in a shadow stack. Because of this,
+ * creating 4-KB guard pages around a shadow stack prevents these
+ * instructions from going beyond.
+ */
+#define ARCH_SHADOW_STACK_GUARD_GAP PAGE_SIZE
+
#endif /* _ASM_X86_PAGE_64_DEFS_H */
diff --git a/include/linux/mm.h b/include/linux/mm.h
index af805ffde48e..9890e9f5a5e0 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2619,6 +2619,10 @@ extern vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf);
int __must_check write_one_page(struct page *page);
void task_dirty_inc(struct task_struct *tsk);
+#ifndef ARCH_SHADOW_STACK_GUARD_GAP
+#define ARCH_SHADOW_STACK_GUARD_GAP 0
+#endif
+
extern unsigned long stack_guard_gap;
/* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */
extern int expand_stack(struct vm_area_struct *vma, unsigned long address);
@@ -2651,9 +2655,15 @@ static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * m
static inline unsigned long vm_start_gap(struct vm_area_struct *vma)
{
unsigned long vm_start = vma->vm_start;
+ unsigned long gap = 0;
- if (vma->vm_flags & VM_GROWSDOWN) {
- vm_start -= stack_guard_gap;
+ if (vma->vm_flags & VM_GROWSDOWN)
+ gap = stack_guard_gap;
+ else if (vma->vm_flags & VM_SHSTK)
+ gap = ARCH_SHADOW_STACK_GUARD_GAP;
+
+ if (gap != 0) {
+ vm_start -= gap;
if (vm_start > vma->vm_start)
vm_start = 0;
}
@@ -2663,9 +2673,15 @@ static inline unsigned long vm_start_gap(struct vm_area_struct *vma)
static inline unsigned long vm_end_gap(struct vm_area_struct *vma)
{
unsigned long vm_end = vma->vm_end;
+ unsigned long gap = 0;
+
+ if (vma->vm_flags & VM_GROWSUP)
+ gap = stack_guard_gap;
+ else if (vma->vm_flags & VM_SHSTK)
+ gap = ARCH_SHADOW_STACK_GUARD_GAP;
- if (vma->vm_flags & VM_GROWSUP) {
- vm_end += stack_guard_gap;
+ if (gap != 0) {
+ vm_end += gap;
if (vm_end < vma->vm_end)
vm_end = -PAGE_SIZE;
}
--
2.21.0
next prev parent reply other threads:[~2021-03-16 15:13 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-16 15:10 [PATCH v23 00/28] Control-flow Enforcement: Shadow Stack Yu-cheng Yu
2021-03-16 15:10 ` [PATCH v23 01/28] Documentation/x86: Add CET description Yu-cheng Yu
2021-03-16 15:10 ` [PATCH v23 02/28] x86/cet/shstk: Add Kconfig option for user-mode control-flow protection Yu-cheng Yu
2021-03-16 15:10 ` [PATCH v23 03/28] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2021-03-16 15:10 ` [PATCH v23 04/28] x86/cpufeatures: Introduce X86_FEATURE_CET and setup functions Yu-cheng Yu
2021-03-16 15:10 ` [PATCH v23 05/28] x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states Yu-cheng Yu
2021-03-16 15:10 ` [PATCH v23 06/28] x86/cet: Add control-protection fault handler Yu-cheng Yu
2021-03-16 15:10 ` [PATCH v23 07/28] x86/mm: Remove _PAGE_DIRTY from kernel RO pages Yu-cheng Yu
2021-03-22 9:13 ` Kirill A. Shutemov
2021-03-22 14:52 ` Yu, Yu-cheng
2021-03-16 15:10 ` [PATCH v23 08/28] x86/mm: Move pmd_write(), pud_write() up in the file Yu-cheng Yu
2021-03-22 11:28 ` Kirill A. Shutemov
2021-03-16 15:10 ` [PATCH v23 09/28] x86/mm: Introduce _PAGE_COW Yu-cheng Yu
2021-03-22 11:29 ` Kirill A. Shutemov
2021-03-16 15:10 ` [PATCH v23 10/28] drm/i915/gvt: Change _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2021-03-22 11:30 ` Kirill A. Shutemov
2021-03-16 15:10 ` [PATCH v23 11/28] x86/mm: Update pte_modify for _PAGE_COW Yu-cheng Yu
2021-03-22 11:31 ` Kirill A. Shutemov
2021-03-16 15:10 ` [PATCH v23 12/28] x86/mm: Update ptep_set_wrprotect() and pmdp_set_wrprotect() for transition from _PAGE_DIRTY to _PAGE_COW Yu-cheng Yu
2021-03-22 10:15 ` Kirill A. Shutemov
2021-03-22 10:46 ` Peter Zijlstra
2021-03-22 11:38 ` Kirill A. Shutemov
2021-03-16 15:10 ` [PATCH v23 13/28] mm: Introduce VM_SHSTK for shadow stack memory Yu-cheng Yu
2021-03-22 11:33 ` Kirill A. Shutemov
2021-03-16 15:10 ` [PATCH v23 14/28] x86/mm: Shadow Stack page fault error checking Yu-cheng Yu
2021-03-22 10:38 ` Kirill A. Shutemov
2021-03-22 17:27 ` Yu, Yu-cheng
2021-03-16 15:10 ` [PATCH v23 15/28] x86/mm: Update maybe_mkwrite() for shadow stack Yu-cheng Yu
2021-03-17 15:56 ` Borislav Petkov
2021-03-22 10:46 ` Kirill A. Shutemov
2021-03-16 15:10 ` [PATCH v23 16/28] mm: Fixup places that call pte_mkwrite() directly Yu-cheng Yu
2021-03-18 9:47 ` Borislav Petkov
2021-03-18 11:16 ` Borislav Petkov
2021-03-16 15:10 ` Yu-cheng Yu [this message]
2021-03-22 10:55 ` [PATCH v23 17/28] mm: Add guard pages around a shadow stack Kirill A. Shutemov
2021-03-16 15:10 ` [PATCH v23 18/28] mm/mmap: Add shadow stack pages to memory accounting Yu-cheng Yu
2021-03-22 10:57 ` Kirill A. Shutemov
2021-03-26 15:46 ` Yu, Yu-cheng
2021-03-29 10:10 ` Kirill A. Shutemov
2021-03-16 15:10 ` [PATCH v23 19/28] mm: Update can_follow_write_pte() for shadow stack Yu-cheng Yu
2021-03-16 15:10 ` [PATCH v23 20/28] mm/mprotect: Exclude shadow stack from preserve_write Yu-cheng Yu
2021-03-16 15:10 ` [PATCH v23 21/28] mm: Re-introduce vm_flags to do_mmap() Yu-cheng Yu
2021-03-18 11:42 ` Borislav Petkov
2021-03-18 15:59 ` Yu, Yu-cheng
2021-03-18 16:13 ` Borislav Petkov
2021-03-16 15:10 ` [PATCH v23 22/28] x86/cet/shstk: User-mode shadow stack support Yu-cheng Yu
2021-03-18 12:32 ` Borislav Petkov
2021-03-18 19:05 ` Yu, Yu-cheng
2021-03-19 9:28 ` Borislav Petkov
2021-03-19 15:15 ` Yu, Yu-cheng
2021-03-16 15:10 ` [PATCH v23 23/28] x86/cet/shstk: Handle signals for shadow stack Yu-cheng Yu
2021-03-19 12:51 ` Borislav Petkov
2021-03-16 15:10 ` [PATCH v23 24/28] ELF: Introduce arch_setup_elf_property() Yu-cheng Yu
2021-03-16 15:10 ` [PATCH v23 25/28] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2021-03-16 15:10 ` [PATCH v23 26/28] x86/cet/shstk: Add arch_prctl functions for " Yu-cheng Yu
2021-03-16 15:10 ` [PATCH v23 27/28] mm: Move arch_calc_vm_prot_bits() to arch/x86/include/asm/mman.h Yu-cheng Yu
2021-03-16 15:10 ` [PATCH v23 28/28] mm: Introduce PROT_SHSTK for shadow stack Yu-cheng Yu
2021-03-22 11:27 ` Kirill A. Shutemov
2021-03-16 21:15 ` [PATCH v23 00/28] Control-flow Enforcement: Shadow Stack Peter Zijlstra
2021-03-16 21:34 ` Yu, Yu-cheng
2021-03-17 9:18 ` Ingo Molnar
2021-03-17 10:14 ` Peter Zijlstra
2021-03-19 16:24 ` Yu, Yu-cheng
2021-03-19 21:43 ` Yu, Yu-cheng
2021-03-23 20:49 ` Peter Zijlstra
2021-03-23 21:03 ` Yu, Yu-cheng
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