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[RFC,3/5] Prevent write to read-only pages text, PLT/GOT tables from another process

Message ID 20200406142045.32522-4-levonshe@gmail.com (mailing list archive)
State New, archived
Headers show
Series Prevent write to read-only pages (text, PLT/GOT | expand

Commit Message

Lev R. Oshvang . April 6, 2020, 2:20 p.m. UTC 
Signed-off-by: Lev Olshvang <levonshe@gmail.com>
---
 arch/powerpc/include/asm/mmu_context.h | 7 ++++++-
 arch/powerpc/mm/book3s64/pkeys.c       | 5 +++++
 2 files changed, 11 insertions(+), 1 deletion(-)

--
2.17.1
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Patch

diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
index 360367c579de..b25e5726fa99 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -246,10 +246,15 @@  void arch_dup_pkeys(struct mm_struct *oldmm, struct mm_struct *mm);
 static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
 		bool write, bool execute, bool foreign)
 {
+#ifdef CONFIG_PROTECT_READONLY_USER_MEMORY
+	/* Forbid write to PROT_READ pages of foreign process */
+	if (write && foreign && (!(vma->vm_flags & VM_WRITE)))
+		return false;
+#endif
 	/* by default, allow everything */
 	return true;
 }
-
+#endif
 #define pkey_mm_init(mm)
 #define thread_pkey_regs_save(thread)
 #define thread_pkey_regs_restore(new_thread, old_thread)
diff --git a/arch/powerpc/mm/book3s64/pkeys.c b/arch/powerpc/mm/book3s64/pkeys.c
index 07527f1ed108..230058a52009 100644
--- a/arch/powerpc/mm/book3s64/pkeys.c
+++ b/arch/powerpc/mm/book3s64/pkeys.c
@@ -384,6 +384,11 @@  bool arch_pte_access_permitted(u64 pte, bool write, bool execute)
 bool arch_vma_access_permitted(struct vm_area_struct *vma, bool write,
 			       bool execute, bool foreign)
 {
+#ifdef CONFIG_PROTECT_READONLY_USER_MEMORY
+	/* Forbid write to PROT_READ pages of foreign process */
+	if (write && foreign && (!(vma->vm_flags & VM_WRITE)))
+		return false;
+#endif
 	if (static_branch_likely(&pkey_disabled))
 		return true;
 	/*