diff options
Diffstat (limited to 'mm/userfaultfd.c')
| -rw-r--r-- | mm/userfaultfd.c | 94 |
1 files changed, 83 insertions, 11 deletions
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index bd96855f3961..512576e171ce 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -53,7 +53,8 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma, unsigned long dst_addr, unsigned long src_addr, - struct page **pagep) + struct page **pagep, + bool wp_copy) { struct mem_cgroup *memcg; pte_t _dst_pte, *dst_pte; @@ -99,9 +100,13 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm, if (mem_cgroup_try_charge(page, dst_mm, GFP_KERNEL, &memcg, false)) goto out_release; - _dst_pte = mk_pte(page, dst_vma->vm_page_prot); - if (dst_vma->vm_flags & VM_WRITE) - _dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte)); + _dst_pte = pte_mkdirty(mk_pte(page, dst_vma->vm_page_prot)); + if (dst_vma->vm_flags & VM_WRITE) { + if (wp_copy) + _dst_pte = pte_mkuffd_wp(_dst_pte); + else + _dst_pte = pte_mkwrite(_dst_pte); + } dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); if (dst_vma->vm_file) { @@ -415,7 +420,8 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, unsigned long dst_addr, unsigned long src_addr, struct page **page, - bool zeropage) + bool zeropage, + bool wp_copy) { ssize_t err; @@ -432,11 +438,13 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, if (!(dst_vma->vm_flags & VM_SHARED)) { if (!zeropage) err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, - dst_addr, src_addr, page); + dst_addr, src_addr, page, + wp_copy); else err = mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma, dst_addr); } else { + VM_WARN_ON_ONCE(wp_copy); if (!zeropage) err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, @@ -454,7 +462,8 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, unsigned long src_start, unsigned long len, bool zeropage, - bool *mmap_changing) + bool *mmap_changing, + __u64 mode) { struct vm_area_struct *dst_vma; ssize_t err; @@ -462,6 +471,7 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, unsigned long src_addr, dst_addr; long copied; struct page *page; + bool wp_copy; /* * Sanitize the command parameters: @@ -508,6 +518,14 @@ retry: goto out_unlock; /* + * validate 'mode' now that we know the dst_vma: don't allow + * a wrprotect copy if the userfaultfd didn't register as WP. + */ + wp_copy = mode & UFFDIO_COPY_MODE_WP; + if (wp_copy && !(dst_vma->vm_flags & VM_UFFD_WP)) + goto out_unlock; + + /* * If this is a HUGETLB vma, pass off to appropriate routine */ if (is_vm_hugetlb_page(dst_vma)) @@ -562,7 +580,7 @@ retry: BUG_ON(pmd_trans_huge(*dst_pmd)); err = mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, - src_addr, &page, zeropage); + src_addr, &page, zeropage, wp_copy); cond_resched(); if (unlikely(err == -ENOENT)) { @@ -609,14 +627,68 @@ out: ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start, unsigned long src_start, unsigned long len, - bool *mmap_changing) + bool *mmap_changing, __u64 mode) { return __mcopy_atomic(dst_mm, dst_start, src_start, len, false, - mmap_changing); + mmap_changing, mode); } ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start, unsigned long len, bool *mmap_changing) { - return __mcopy_atomic(dst_mm, start, 0, len, true, mmap_changing); + return __mcopy_atomic(dst_mm, start, 0, len, true, mmap_changing, 0); +} + +int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, + unsigned long len, bool enable_wp, bool *mmap_changing) +{ + struct vm_area_struct *dst_vma; + pgprot_t newprot; + int err; + + /* + * Sanitize the command parameters: + */ + BUG_ON(start & ~PAGE_MASK); + BUG_ON(len & ~PAGE_MASK); + + /* Does the address range wrap, or is the span zero-sized? */ + BUG_ON(start + len <= start); + + down_read(&dst_mm->mmap_sem); + + /* + * If memory mappings are changing because of non-cooperative + * operation (e.g. mremap) running in parallel, bail out and + * request the user to retry later + */ + err = -EAGAIN; + if (mmap_changing && READ_ONCE(*mmap_changing)) + goto out_unlock; + + err = -ENOENT; + dst_vma = find_dst_vma(dst_mm, start, len); + /* + * Make sure the vma is not shared, that the dst range is + * both valid and fully within a single existing vma. + */ + if (!dst_vma || (dst_vma->vm_flags & VM_SHARED)) + goto out_unlock; + if (!userfaultfd_wp(dst_vma)) + goto out_unlock; + if (!vma_is_anonymous(dst_vma)) + goto out_unlock; + + if (enable_wp) + newprot = vm_get_page_prot(dst_vma->vm_flags & ~(VM_WRITE)); + else + newprot = vm_get_page_prot(dst_vma->vm_flags); + + change_protection(dst_vma, start, start + len, newprot, + enable_wp ? MM_CP_UFFD_WP : MM_CP_UFFD_WP_RESOLVE); + + err = 0; +out_unlock: + up_read(&dst_mm->mmap_sem); + return err; } |