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

Lev Olshvang
2020-04-06T14:59:26Z

arch/powerpc/include/asm/mmu_context.h | 7 ++++++-
arch/powerpc/mm/book3s64/pkeys.c | 5 +++++
2 files changed, 11 insertions(+), 1 deletion(-)

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;
/*
--
2.17.1