[PATCH v10 12/26] mm: Introduce VM_SHSTK for shadow stack memory
STALE2262d
REVIEWED: 1 (0M)
From: Yu-cheng Yu <hidden>
Date: 2020-04-29 22:08:54
Also in:
linux-arch, linux-doc, linux-mm, lkml
Subsystem:
filesystems (vfs and infrastructure), memory management - core, memory mapping, proc filesystem, the rest, x86 architecture (32-bit and 64-bit), x86 mm · Maintainers:
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 v10 of 26 in this series; 1 review trailer.
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_SHSTK to track shadow stack VMAs. Signed-off-by: Yu-cheng Yu <redacted> Reviewed-by: Kees Cook <redacted> --- v9: - Add VM_SHSTK case to arch_vma_name(). - Revise the commit log to explain why adding a new VM flag. 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 cb91eccc4960..fe77fd6debf1 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c@@ -163,6 +163,8 @@ unsigned long get_mmap_base(int is_legacy) const char *arch_vma_name(struct vm_area_struct *vma) { + 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 8d382d4ec067..434692759265 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c@@ -657,6 +657,9 @@ 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 5a323422d783..54bb4cd9fee8 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -294,11 +294,13 @@ 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
@@ -336,6 +338,12 @@ 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
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2.21.0