[PATCH v24 13/30] mm: Introduce VM_SHADOW_STACK for shadow stack memory
STALE2002d
From: Yu-cheng Yu <hidden>
Date: 2021-04-01 22:12:09
Also in:
linux-api, linux-arch, linux-mm, lkml
Subsystem:
documentation, filesystems (vfs and infrastructure), memory management - core, memory mapping, proc filesystem, the rest, x86 architecture (32-bit and 64-bit), x86 mm · Maintainers:
Jonathan Corbet, Alexander Viro, Christian Brauner, Andrew Morton, David Hildenbrand, Liam R. Howlett, Lorenzo Stoakes, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Andy Lutomirski, Peter Zijlstra
Revision v24 of 26 in this series.
Revisions (26)
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A shadow stack 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. Introduce VM_SHADOW_STACK to track shadow stack VMAs. Signed-off-by: Yu-cheng Yu <redacted> Cc: Kees Cook <redacted> Cc: Kirill A. Shutemov <redacted> --- v24: - Change VM_SHSTK to VM_SHADOW_STACK. - Change CONFIG_X86_CET to CONFIG_X86_SHADOW_STACK to reflect Kconfig changes. Documentation/filesystems/proc.rst | 1 + arch/x86/mm/mmap.c | 2 ++ fs/proc/task_mmu.c | 3 +++ include/linux/mm.h | 8 ++++++++ 4 files changed, 14 insertions(+)
diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
index 48fbfc336ebf..5d8a2d75c799 100644
--- a/Documentation/filesystems/proc.rst
+++ b/Documentation/filesystems/proc.rst@@ -549,6 +549,7 @@ encoded manner. The codes are the following: mg mergable advise flag bt arm64 BTI guarded page mt arm64 MTE allocation tags are enabled + ss shadow stack page == ======================================= Note that there is no guarantee that every flag and associated mnemonic will
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index c90c20904a60..f3f52c5e2fd6 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c@@ -165,6 +165,8 @@ unsigned long get_mmap_base(int is_legacy) const char *arch_vma_name(struct vm_area_struct *vma) { + if (vma->vm_flags & VM_SHADOW_STACK) + return "[shadow stack]"; return NULL; }
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index e862cab69583..0aa57de9dfab 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c@@ -661,6 +661,9 @@ 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_ARCH_HAS_SHADOW_STACK + [ilog2(VM_SHADOW_STACK)]= "ss", +#endif }; size_t i;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 8ba434287387..08282eb2f195 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -312,11 +312,13 @@ 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
@@ -332,6 +334,12 @@ extern unsigned int kobjsize(const void *objp); #endif #endif /* CONFIG_ARCH_HAS_PKEYS */ +#ifdef CONFIG_X86_SHADOW_STACK +# define VM_SHADOW_STACK VM_HIGH_ARCH_5 +#else +# define VM_SHADOW_STACK VM_NONE +#endif + #if defined(CONFIG_X86) # define VM_PAT VM_ARCH_1 /* PAT reserves whole VMA at once (x86) */ #elif defined(CONFIG_PPC)
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2.21.0