diff options
| author | David Hildenbrand <david@redhat.com> | 2022-12-23 16:56:16 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-01-18 17:12:50 -0800 |
| commit | 1ef488edd6c4d447784710974f049628c2890481 (patch) | |
| tree | a3577746e57294945403990ca3dd33a9a0986ee4 | |
| parent | 931298e103c228c4ce6d13e7b5781aeaaff37ac7 (diff) | |
mm/mprotect: drop pgprot_t parameter from change_protection()
Being able to provide a custom protection opens the door for
inconsistencies and BUGs: for example, accidentally allowing for more
permissions than desired by other mechanisms (e.g., softdirty tracking).
vma->vm_page_prot should be the single source of truth.
Only PROT_NUMA is special: there is no way we can erroneously allow
for more permissions when removing all permissions. Special-case using
the MM_CP_PROT_NUMA flag.
[david@redhat.com: PAGE_NONE might not be defined without CONFIG_NUMA_BALANCING]
Link: https://lkml.kernel.org/r/5084ff1c-ebb3-f918-6a60-bacabf550a88@redhat.com
Link: https://lkml.kernel.org/r/20221223155616.297723-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | include/linux/mm.h | 3 | ||||
| -rw-r--r-- | mm/mempolicy.c | 3 | ||||
| -rw-r--r-- | mm/mprotect.c | 18 | ||||
| -rw-r--r-- | mm/userfaultfd.c | 3 |
4 files changed, 18 insertions, 9 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index d68579bf8484..329ed67edd76 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2134,8 +2134,7 @@ bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr, pte_t pte); extern unsigned long change_protection(struct mmu_gather *tlb, struct vm_area_struct *vma, unsigned long start, - unsigned long end, pgprot_t newprot, - unsigned long cp_flags); + unsigned long end, unsigned long cp_flags); extern int mprotect_fixup(struct mmu_gather *tlb, struct vm_area_struct *vma, struct vm_area_struct **pprev, unsigned long start, unsigned long end, unsigned long newflags); diff --git a/mm/mempolicy.c b/mm/mempolicy.c index becf41e10076..d3558248a0f0 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -635,8 +635,7 @@ unsigned long change_prot_numa(struct vm_area_struct *vma, tlb_gather_mmu(&tlb, vma->vm_mm); - nr_updated = change_protection(&tlb, vma, addr, end, PAGE_NONE, - MM_CP_PROT_NUMA); + nr_updated = change_protection(&tlb, vma, addr, end, MM_CP_PROT_NUMA); if (nr_updated) count_vm_numa_events(NUMA_PTE_UPDATES, nr_updated); diff --git a/mm/mprotect.c b/mm/mprotect.c index bf8fa0af5a15..71358e45a742 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -507,13 +507,25 @@ static unsigned long change_protection_range(struct mmu_gather *tlb, unsigned long change_protection(struct mmu_gather *tlb, struct vm_area_struct *vma, unsigned long start, - unsigned long end, pgprot_t newprot, - unsigned long cp_flags) + unsigned long end, unsigned long cp_flags) { + pgprot_t newprot = vma->vm_page_prot; unsigned long pages; BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL); +#ifdef CONFIG_NUMA_BALANCING + /* + * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking) + * are expected to reflect their requirements via VMA flags such that + * vma_set_page_prot() will adjust vma->vm_page_prot accordingly. + */ + if (cp_flags & MM_CP_PROT_NUMA) + newprot = PAGE_NONE; +#else + WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA); +#endif + if (is_vm_hugetlb_page(vma)) pages = hugetlb_change_protection(vma, start, end, newprot, cp_flags); @@ -642,7 +654,7 @@ success: mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; vma_set_page_prot(vma); - change_protection(tlb, vma, start, end, vma->vm_page_prot, mm_cp_flags); + change_protection(tlb, vma, start, end, mm_cp_flags); /* * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 46771362550f..65ad172add27 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -730,8 +730,7 @@ void uffd_wp_range(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma, if (!enable_wp && vma_wants_manual_pte_write_upgrade(dst_vma)) mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; tlb_gather_mmu(&tlb, dst_mm); - change_protection(&tlb, dst_vma, start, start + len, vma->vm_page_prot, - mm_cp_flags); + change_protection(&tlb, dst_vma, start, start + len, mm_cp_flags); tlb_finish_mmu(&tlb); } |