From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yu-cheng Yu Subject: [RFC PATCH v9 06/27] mm: Introduce VM_SHSTK for Shadow Stack memory Date: Wed, 5 Feb 2020 10:19:14 -0800 Message-ID: <20200205181935.3712-7-yu-cheng.yu@intel.com> References: <20200205181935.3712-1-yu-cheng.yu@intel.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200205181935.3712-1-yu-cheng.yu@intel.com> Sender: linux-kernel-owner@vger.kernel.org To: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , 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 , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit Cc: Yu-cheng Yu List-Id: linux-arch.vger.kernel.org A Shadow Stack (SHSTK) PTE must be read-only and have _PAGE_DIRTY set. However, read-only and Dirty PTEs also exist for copy-on-write (COW) pages. These two cases are handled differently for page faults and a new VM flag is necessary for tracking SHSTK VMAs. v9: - Add VM_SHSTK case to arch_vma_name(). - Revise the commit log to explain why a new VM flag is needed. Signed-off-by: Yu-cheng Yu --- arch/x86/mm/mmap.c | 2 ++ fs/proc/task_mmu.c | 3 +++ include/linux/mm.h | 8 ++++++++ 3 files changed, 13 insertions(+) diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c index aae9a933dfd4..482813b4c659 100644 --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -165,6 +165,8 @@ const char *arch_vma_name(struct vm_area_struct *vma) { if (vma->vm_flags & VM_MPX) return "[mpx]"; + else if (vma->vm_flags & VM_SHSTK) + return "[shadow stack]"; return NULL; } diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 9442631fd4af..590b58ee008a 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -687,6 +687,9 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma) [ilog2(VM_PKEY_BIT4)] = "", #endif #endif /* CONFIG_ARCH_HAS_PKEYS */ +#ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER + [ilog2(VM_SHSTK)] = "ss", +#endif }; size_t i; diff --git a/include/linux/mm.h b/include/linux/mm.h index cfaa8feecfe8..b5145fbe102e 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -298,11 +298,13 @@ extern unsigned int kobjsize(const void *objp); #define VM_HIGH_ARCH_BIT_2 34 /* bit only usable on 64-bit architectures */ #define VM_HIGH_ARCH_BIT_3 35 /* bit only usable on 64-bit architectures */ #define VM_HIGH_ARCH_BIT_4 36 /* bit only usable on 64-bit architectures */ +#define VM_HIGH_ARCH_BIT_5 37 /* bit only usable on 64-bit architectures */ #define VM_HIGH_ARCH_0 BIT(VM_HIGH_ARCH_BIT_0) #define VM_HIGH_ARCH_1 BIT(VM_HIGH_ARCH_BIT_1) #define VM_HIGH_ARCH_2 BIT(VM_HIGH_ARCH_BIT_2) #define VM_HIGH_ARCH_3 BIT(VM_HIGH_ARCH_BIT_3) #define VM_HIGH_ARCH_4 BIT(VM_HIGH_ARCH_BIT_4) +#define VM_HIGH_ARCH_5 BIT(VM_HIGH_ARCH_BIT_5) #endif /* CONFIG_ARCH_USES_HIGH_VMA_FLAGS */ #ifdef CONFIG_ARCH_HAS_PKEYS @@ -340,6 +342,12 @@ extern unsigned int kobjsize(const void *objp); # define VM_MPX VM_NONE #endif +#ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER +# define VM_SHSTK VM_HIGH_ARCH_5 +#else +# define VM_SHSTK VM_NONE +#endif + #ifndef VM_GROWSUP # define VM_GROWSUP VM_NONE #endif -- 2.21.0 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Yu-cheng Yu Subject: [RFC PATCH v9 06/27] mm: Introduce VM_SHSTK for Shadow Stack memory Date: Wed, 5 Feb 2020 10:19:14 -0800 Message-ID: <20200205181935.3712-7-yu-cheng.yu@intel.com> In-Reply-To: <20200205181935.3712-1-yu-cheng.yu@intel.com> References: <20200205181935.3712-1-yu-cheng.yu@intel.com> MIME-Version: 1.0 Sender: linux-doc-owner@vger.kernel.org Content-Transfer-Encoding: quoted-printable To: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , 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 , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , x86-patch-review@intel.com Cc: Yu-cheng Yu List-ID: Message-ID: <20200205181914._fj-FoFPcOxmS0b7GKdg4F_MF0jQq8OgtsA7lo3FjEM@z> A Shadow Stack (SHSTK) PTE must be read-only and have _PAGE_DIRTY set. However, read-only and Dirty PTEs also exist for copy-on-write (COW) page= s. These two cases are handled differently for page faults and a new VM flag is necessary for tracking SHSTK VMAs. v9: - Add VM_SHSTK case to arch_vma_name(). - Revise the commit log to explain why a new VM flag is needed. Signed-off-by: Yu-cheng Yu --- arch/x86/mm/mmap.c | 2 ++ fs/proc/task_mmu.c | 3 +++ include/linux/mm.h | 8 ++++++++ 3 files changed, 13 insertions(+) diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c index aae9a933dfd4..482813b4c659 100644 --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -165,6 +165,8 @@ const char *arch_vma_name(struct vm_area_struct *vma) { if (vma->vm_flags & VM_MPX) return "[mpx]"; + else if (vma->vm_flags & VM_SHSTK) + return "[shadow stack]"; return NULL; } diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 9442631fd4af..590b58ee008a 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -687,6 +687,9 @@ static void show_smap_vma_flags(struct seq_file *m, s= truct vm_area_struct *vma) [ilog2(VM_PKEY_BIT4)] =3D "", #endif #endif /* CONFIG_ARCH_HAS_PKEYS */ +#ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER + [ilog2(VM_SHSTK)] =3D "ss", +#endif }; size_t i; diff --git a/include/linux/mm.h b/include/linux/mm.h index cfaa8feecfe8..b5145fbe102e 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -298,11 +298,13 @@ extern unsigned int kobjsize(const void *objp); #define VM_HIGH_ARCH_BIT_2 34 /* bit only usable on 64-bit architectures= */ #define VM_HIGH_ARCH_BIT_3 35 /* bit only usable on 64-bit architectures= */ #define VM_HIGH_ARCH_BIT_4 36 /* bit only usable on 64-bit architectures= */ +#define VM_HIGH_ARCH_BIT_5 37 /* bit only usable on 64-bit architectures= */ #define VM_HIGH_ARCH_0 BIT(VM_HIGH_ARCH_BIT_0) #define VM_HIGH_ARCH_1 BIT(VM_HIGH_ARCH_BIT_1) #define VM_HIGH_ARCH_2 BIT(VM_HIGH_ARCH_BIT_2) #define VM_HIGH_ARCH_3 BIT(VM_HIGH_ARCH_BIT_3) #define VM_HIGH_ARCH_4 BIT(VM_HIGH_ARCH_BIT_4) +#define VM_HIGH_ARCH_5 BIT(VM_HIGH_ARCH_BIT_5) #endif /* CONFIG_ARCH_USES_HIGH_VMA_FLAGS */ #ifdef CONFIG_ARCH_HAS_PKEYS @@ -340,6 +342,12 @@ extern unsigned int kobjsize(const void *objp); # define VM_MPX VM_NONE #endif +#ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER +# define VM_SHSTK VM_HIGH_ARCH_5 +#else +# define VM_SHSTK VM_NONE +#endif + #ifndef VM_GROWSUP # define VM_GROWSUP VM_NONE #endif --=20 2.21.0