[PATCH v14 14/26] x86/mm: Update maybe_mkwrite() for shadow stack
From: Yu-cheng Yu <hidden>
Date: 2020-10-09 18:33:45
Also in:
linux-api, linux-doc, linux-mm, lkml
Subsystem:
memory management, memory management - core, memory management - thp (transparent huge page), the rest, x86 architecture (32-bit and 64-bit), x86 mm · Maintainers:
Andrew Morton, David Hildenbrand, Lorenzo Stoakes, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Andy Lutomirski, Peter Zijlstra
Shadow stack memory is writable, but its VMA has VM_SHSTK instead of VM_WRITE. Update maybe_mkwrite() to include the shadow stack. Signed-off-by: Yu-cheng Yu <redacted> --- arch/x86/Kconfig | 4 ++++ arch/x86/mm/pgtable.c | 18 ++++++++++++++++++ include/linux/mm.h | 2 ++ include/linux/pgtable.h | 24 ++++++++++++++++++++++++ mm/huge_memory.c | 2 ++ 5 files changed, 50 insertions(+)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 415fcc869afc..7578327226e3 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig@@ -1935,6 +1935,9 @@ config AS_HAS_SHADOW_STACK config X86_CET def_bool n +config ARCH_MAYBE_MKWRITE + def_bool n + config ARCH_HAS_SHADOW_STACK def_bool n
@@ -1945,6 +1948,7 @@ config X86_SHADOW_STACK_USER depends on AS_HAS_SHADOW_STACK select ARCH_USES_HIGH_VMA_FLAGS select X86_CET + select ARCH_MAYBE_MKWRITE select ARCH_HAS_SHADOW_STACK help Shadow Stacks provides protection against program stack
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index dfd82f51ba66..a9666b64bc05 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c@@ -610,6 +610,24 @@ int pmdp_clear_flush_young(struct vm_area_struct *vma, } #endif +#ifdef CONFIG_ARCH_MAYBE_MKWRITE +pte_t arch_maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) +{ + if (likely(vma->vm_flags & VM_SHSTK)) + pte = pte_mkwrite_shstk(pte); + return pte; +} + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +pmd_t arch_maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) +{ + if (likely(vma->vm_flags & VM_SHSTK)) + pmd = pmd_mkwrite_shstk(pmd); + return pmd; +} +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ +#endif /* CONFIG_ARCH_MAYBE_MKWRITE */ + /** * reserve_top_address - reserves a hole in the top of kernel address space * @reserve - size of hole to reserve
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 12be96b061c7..4f6305106feb 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -969,6 +969,8 @@ static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) { if (likely(vma->vm_flags & VM_WRITE)) pte = pte_mkwrite(pte); + else + pte = arch_maybe_mkwrite(pte, vma); return pte; }
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 90654cb63e9e..157f5e726896 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h@@ -1356,6 +1356,30 @@ static inline bool arch_has_pfn_modify_check(void) } #endif /* !_HAVE_ARCH_PFN_MODIFY_ALLOWED */ +#ifdef CONFIG_MMU +#ifdef CONFIG_ARCH_MAYBE_MKWRITE +pte_t arch_maybe_mkwrite(pte_t pte, struct vm_area_struct *vma); + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +pmd_t arch_maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma); +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ + +#else /* !CONFIG_ARCH_MAYBE_MKWRITE */ +static inline pte_t arch_maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) +{ + return pte; +} + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +static inline pmd_t arch_maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) +{ + return pmd; +} +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ + +#endif /* CONFIG_ARCH_MAYBE_MKWRITE */ +#endif /* CONFIG_MMU */ + /* * Architecture PAGE_KERNEL_* fallbacks *
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index da397779a6d4..01252b00cd06 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c@@ -464,6 +464,8 @@ pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) { if (likely(vma->vm_flags & VM_WRITE)) pmd = pmd_mkwrite(pmd); + else + pmd = arch_maybe_pmd_mkwrite(pmd, vma); return pmd; }
--
2.21.0