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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>,
	x86-patch-review@intel.com
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: [RFC PATCH v9 14/27] mm: Handle Shadow Stack page fault
Date: Wed,  5 Feb 2020 10:19:22 -0800	[thread overview]
Message-ID: <20200205181935.3712-15-yu-cheng.yu@intel.com> (raw)
In-Reply-To: <20200205181935.3712-1-yu-cheng.yu@intel.com>

When a task does fork(), its Shadow Stack (SHSTK) must be duplicated for
the child.  This patch implements a flow similar to copy-on-write of an
anonymous page, but for SHSTK.

A SHSTK PTE must be RO and Dirty.  This Dirty bit requirement is used to
effect the copying.  In copy_one_pte(), clear the Dirty bit from a SHSTK
PTE to cause a page fault upon the next SHSTK access.  At that time, fix
the PTE and copy/re-use the page.

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
 arch/x86/mm/pgtable.c         | 15 +++++++++++++++
 include/asm-generic/pgtable.h | 17 +++++++++++++++++
 mm/memory.c                   |  7 ++++++-
 3 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 7bd2c3a52297..2eb33794c08d 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -872,3 +872,18 @@ int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
 
 #endif /* CONFIG_X86_64 */
 #endif	/* CONFIG_HAVE_ARCH_HUGE_VMAP */
+
+#ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER
+inline bool arch_copy_pte_mapping(vm_flags_t vm_flags)
+{
+	return (vm_flags & VM_SHSTK);
+}
+
+inline pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma)
+{
+	if (vma->vm_flags & VM_SHSTK)
+		return pte_mkdirty_shstk(pte);
+	else
+		return pte;
+}
+#endif /* CONFIG_X86_INTEL_SHADOW_STACK_USER */
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 798ea36a0549..9cb2f9ba5895 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -1190,6 +1190,23 @@ static inline bool arch_has_pfn_modify_check(void)
 }
 #endif /* !_HAVE_ARCH_PFN_MODIFY_ALLOWED */
 
+#ifdef CONFIG_MMU
+#ifndef CONFIG_ARCH_HAS_SHSTK
+static inline bool arch_copy_pte_mapping(vm_flags_t vm_flags)
+{
+	return false;
+}
+
+static inline pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma)
+{
+	return pte;
+}
+#else
+bool arch_copy_pte_mapping(vm_flags_t vm_flags);
+pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma);
+#endif
+#endif /* CONFIG_MMU */
+
 /*
  * Architecture PAGE_KERNEL_* fallbacks
  *
diff --git a/mm/memory.c b/mm/memory.c
index 45442d9a4f52..6daa28614327 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -772,7 +772,8 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 	 * If it's a COW mapping, write protect it both
 	 * in the parent and the child
 	 */
-	if (is_cow_mapping(vm_flags) && pte_write(pte)) {
+	if ((is_cow_mapping(vm_flags) && pte_write(pte)) ||
+	    arch_copy_pte_mapping(vm_flags)) {
 		ptep_set_wrprotect(src_mm, addr, src_pte);
 		pte = pte_wrprotect(pte);
 	}
@@ -2417,6 +2418,7 @@ static inline void wp_page_reuse(struct vm_fault *vmf)
 	flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
 	entry = pte_mkyoung(vmf->orig_pte);
 	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+	entry = pte_set_vma_features(entry, vma);
 	if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
 		update_mmu_cache(vma, vmf->address, vmf->pte);
 	pte_unmap_unlock(vmf->pte, vmf->ptl);
@@ -2504,6 +2506,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
 		flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
 		entry = mk_pte(new_page, vma->vm_page_prot);
 		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+		entry = pte_set_vma_features(entry, vma);
 		/*
 		 * Clear the pte entry and flush it first, before updating the
 		 * pte with the new entry. This will avoid a race condition
@@ -3023,6 +3026,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 	pte = mk_pte(page, vma->vm_page_prot);
 	if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
 		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
+		pte = pte_set_vma_features(pte, vma);
 		vmf->flags &= ~FAULT_FLAG_WRITE;
 		ret |= VM_FAULT_WRITE;
 		exclusive = RMAP_EXCLUSIVE;
@@ -3165,6 +3169,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
 	entry = mk_pte(page, vma->vm_page_prot);
 	if (vma->vm_flags & VM_WRITE)
 		entry = pte_mkwrite(pte_mkdirty(entry));
+	entry = pte_set_vma_features(entry, vma);
 
 	vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
 			&vmf->ptl);
-- 
2.21.0



  parent reply	other threads:[~2020-02-05 18:21 UTC|newest]

Thread overview: 107+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-05 18:19 [RFC PATCH v9 00/27] Control-flow Enforcement: Shadow Stack Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 01/27] Documentation/x86: Add CET description Yu-cheng Yu
2020-02-06  0:16   ` Randy Dunlap
2020-02-06 20:17     ` Yu-cheng Yu
2020-02-25 20:02   ` Kees Cook
2020-02-28 15:55     ` Yu-cheng Yu
2020-02-26 17:57   ` Dave Hansen
2020-03-09 17:00     ` Yu-cheng Yu
2020-03-09 17:21       ` Dave Hansen
2020-03-09 19:27         ` Yu-cheng Yu
2020-03-09 19:35           ` Dave Hansen
2020-03-09 19:50             ` H.J. Lu
2020-03-09 20:16               ` Andy Lutomirski
2020-03-09 20:54                 ` H.J. Lu
2020-03-09 20:59                   ` Dave Hansen
2020-03-09 21:12                     ` H.J. Lu
2020-03-09 22:02                       ` Andy Lutomirski
2020-03-09 22:19                       ` Dave Hansen
2020-03-09 23:11                         ` H.J. Lu
2020-03-09 23:20                           ` Dave Hansen
2020-03-09 23:51                             ` H.J. Lu
2020-03-09 23:59                               ` Andy Lutomirski
2020-03-10  0:08                                 ` H.J. Lu
2020-03-10  1:21                                   ` Andy Lutomirski
2020-03-10  2:13                                     ` H.J. Lu
2020-02-05 18:19 ` [RFC PATCH v9 02/27] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2020-02-25 20:02   ` Kees Cook
2020-02-05 18:19 ` [RFC PATCH v9 03/27] x86/fpu/xstate: Introduce CET MSR XSAVES supervisor states Yu-cheng Yu
2020-02-25 20:04   ` Kees Cook
2020-02-05 18:19 ` [RFC PATCH v9 04/27] x86/cet: Add control-protection fault handler Yu-cheng Yu
2020-02-25 20:06   ` Kees Cook
2020-02-26 17:10   ` Dave Hansen
2020-03-05 20:44     ` Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 05/27] x86/cet/shstk: Add Kconfig option for user-mode Shadow Stack protection Yu-cheng Yu
2020-02-25 20:07   ` Kees Cook
2020-02-26 17:03   ` Dave Hansen
2020-02-26 19:57     ` Pavel Machek
2020-03-05 20:38     ` Yu-cheng Yu
2020-02-26 18:05   ` Dave Hansen
2020-02-27  1:02     ` H.J. Lu
2020-02-27  1:16       ` Dave Hansen
2020-02-27  2:11         ` H.J. Lu
2020-02-27  3:57           ` Andy Lutomirski
2020-02-27 18:03             ` Dave Hansen
2020-03-06 18:37     ` Yu-cheng Yu
2020-03-06 19:02       ` Dave Hansen
2020-03-06 21:16         ` Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 06/27] mm: Introduce VM_SHSTK for Shadow Stack memory Yu-cheng Yu
2020-02-25 20:07   ` Kees Cook
2020-02-26 18:07   ` Dave Hansen
2020-02-05 18:19 ` [RFC PATCH v9 07/27] Add guard pages around a Shadow Stack Yu-cheng Yu
2020-02-25 20:11   ` Kees Cook
2020-02-26 18:17   ` Dave Hansen
2020-02-05 18:19 ` [RFC PATCH v9 08/27] x86/mm: Change _PAGE_DIRTY to _PAGE_DIRTY_HW Yu-cheng Yu
2020-02-25 20:12   ` Kees Cook
2020-02-26 18:20   ` Dave Hansen
2020-02-05 18:19 ` [RFC PATCH v9 09/27] x86/mm: Introduce _PAGE_DIRTY_SW Yu-cheng Yu
2020-02-25 20:12   ` Kees Cook
2020-02-26 21:35   ` Dave Hansen
2020-04-01 19:08     ` Yu-cheng Yu
2020-04-01 19:22       ` Dave Hansen
2020-02-05 18:19 ` [RFC PATCH v9 10/27] x86/mm: Update pte_modify, pmd_modify, and _PAGE_CHG_MASK for _PAGE_DIRTY_SW Yu-cheng Yu
2020-02-26 22:02   ` Dave Hansen
2020-02-05 18:19 ` [RFC PATCH v9 11/27] drm/i915/gvt: Change _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2020-02-25 20:13   ` Kees Cook
2020-02-26 22:04   ` Dave Hansen
2020-04-03 15:42     ` Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 12/27] x86/mm: Modify ptep_set_wrprotect and pmdp_set_wrprotect for _PAGE_DIRTY_SW Yu-cheng Yu
2020-02-25 20:14   ` Kees Cook
2020-02-26 22:20   ` Dave Hansen
2020-02-05 18:19 ` [RFC PATCH v9 13/27] x86/mm: Shadow Stack page fault error checking Yu-cheng Yu
2020-02-25 20:16   ` Kees Cook
2020-02-26 22:47   ` Dave Hansen
2020-02-05 18:19 ` Yu-cheng Yu [this message]
2020-02-25 20:20   ` [RFC PATCH v9 14/27] mm: Handle Shadow Stack page fault Kees Cook
2020-03-05 18:30     ` Yu-cheng Yu
2020-02-27  0:08   ` Dave Hansen
2020-04-07 18:14     ` Yu-cheng Yu
2020-04-07 22:21       ` Dave Hansen
2020-04-08 18:18         ` Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 15/27] mm: Handle THP/HugeTLB " Yu-cheng Yu
2020-02-25 20:59   ` Kees Cook
2020-03-13 22:00     ` Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 16/27] mm: Update can_follow_write_pte() for Shadow Stack Yu-cheng Yu
2020-02-27  0:34   ` Dave Hansen
2020-02-05 18:19 ` [RFC PATCH v9 17/27] x86/cet/shstk: User-mode Shadow Stack support Yu-cheng Yu
2020-02-25 21:07   ` Kees Cook
2020-02-27  0:55   ` Dave Hansen
2020-02-05 18:19 ` [RFC PATCH v9 18/27] x86/cet/shstk: Introduce WRUSS instruction Yu-cheng Yu
2020-02-25 21:10   ` Kees Cook
2020-03-05 18:39     ` Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 19/27] x86/cet/shstk: Handle signals for Shadow Stack Yu-cheng Yu
2020-02-25 21:17   ` Kees Cook
2020-02-05 18:19 ` [RFC PATCH v9 20/27] ELF: UAPI and Kconfig additions for ELF program properties Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 21/27] binfmt_elf: Define GNU_PROPERTY_X86_FEATURE_1_AND Yu-cheng Yu
2020-02-25 21:18   ` Kees Cook
2020-02-05 18:19 ` [RFC PATCH v9 22/27] ELF: Add ELF program property parsing support Yu-cheng Yu
2020-02-25 21:20   ` Kees Cook
2020-02-05 18:19 ` [RFC PATCH v9 23/27] ELF: Introduce arch_setup_elf_property() Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 24/27] x86/cet/shstk: ELF header parsing for Shadow Stack Yu-cheng Yu
2020-02-25 21:22   ` Kees Cook
2020-02-05 18:19 ` [RFC PATCH v9 25/27] x86/cet/shstk: Handle thread " Yu-cheng Yu
2020-02-25 21:29   ` Kees Cook
2020-03-25 21:51     ` Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 26/27] mm/mmap: Add Shadow Stack pages to memory accounting Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 27/27] x86/cet/shstk: Add arch_prctl functions for Shadow Stack Yu-cheng Yu
2020-02-25 21:31 ` [RFC PATCH v9 00/27] Control-flow Enforcement: " Kees Cook

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