From: Peter Xu <peterx@redhat.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: David Hildenbrand <david@redhat.com>,
Hugh Dickins <hughd@google.com>, Maya Gokhale <gokhale2@llnl.gov>,
Jerome Glisse <jglisse@redhat.com>,
Pavel Emelyanov <xemul@virtuozzo.com>,
Johannes Weiner <hannes@cmpxchg.org>,
peterx@redhat.com, Martin Cracauer <cracauer@cons.org>,
Shaohua Li <shli@fb.com>,
Denis Plotnikov <dplotnikov@virtuozzo.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Marty McFadden <mcfadden8@llnl.gov>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Mel Gorman <mgorman@suse.de>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
Rik van Riel <riel@redhat.com>
Subject: [PATCH v4 20/27] userfaultfd: wp: support write protection for userfault vma range
Date: Fri, 26 Apr 2019 12:51:44 +0800 [thread overview]
Message-ID: <20190426045151.19556-21-peterx@redhat.com> (raw)
In-Reply-To: <20190426045151.19556-1-peterx@redhat.com>
From: Shaohua Li <shli@fb.com>
Add API to enable/disable writeprotect a vma range. Unlike mprotect,
this doesn't split/merge vmas.
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
[peterx:
- use the helper to find VMA;
- return -ENOENT if not found to match mcopy case;
- use the new MM_CP_UFFD_WP* flags for change_protection
- check against mmap_changing for failures]
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
include/linux/userfaultfd_k.h | 3 ++
mm/userfaultfd.c | 54 +++++++++++++++++++++++++++++++++++
2 files changed, 57 insertions(+)
diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index 765ce884cec0..8f6e6ed544fb 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -39,6 +39,9 @@ extern ssize_t mfill_zeropage(struct mm_struct *dst_mm,
unsigned long dst_start,
unsigned long len,
bool *mmap_changing);
+extern int mwriteprotect_range(struct mm_struct *dst_mm,
+ unsigned long start, unsigned long len,
+ bool enable_wp, bool *mmap_changing);
/* mm helpers */
static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 2606409572b2..70cea2ff3960 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -639,3 +639,57 @@ ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start,
{
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 = vma_find_uffd(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;
+}
--
2.17.1
next prev parent reply other threads:[~2019-04-26 4:55 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-26 4:51 [PATCH v4 00/27] userfaultfd: write protection support Peter Xu
2019-04-26 4:51 ` [PATCH v4 01/27] mm: gup: rename "nonblocking" to "locked" where proper Peter Xu
2019-04-26 4:51 ` [PATCH v4 02/27] mm: userfault: return VM_FAULT_RETRY on signals Peter Xu
2019-04-26 4:51 ` [PATCH v4 03/27] userfaultfd: don't retake mmap_sem to emulate NOPAGE Peter Xu
2019-04-26 4:51 ` [PATCH v4 04/27] mm: allow VM_FAULT_RETRY for multiple times Peter Xu
2019-04-26 4:51 ` [PATCH v4 05/27] mm: gup: " Peter Xu
2019-04-26 4:51 ` [PATCH v4 06/27] userfaultfd: wp: add helper for writeprotect check Peter Xu
2019-04-26 4:51 ` [PATCH v4 07/27] userfaultfd: wp: hook userfault handler to write protection fault Peter Xu
2019-04-26 4:51 ` [PATCH v4 08/27] userfaultfd: wp: add WP pagetable tracking to x86 Peter Xu
2019-04-26 4:51 ` [PATCH v4 09/27] userfaultfd: wp: userfaultfd_pte/huge_pmd_wp() helpers Peter Xu
2019-04-26 4:51 ` [PATCH v4 10/27] userfaultfd: wp: add UFFDIO_COPY_MODE_WP Peter Xu
2019-04-26 4:51 ` [PATCH v4 11/27] mm: merge parameters for change_protection() Peter Xu
2019-04-26 4:51 ` [PATCH v4 12/27] userfaultfd: wp: apply _PAGE_UFFD_WP bit Peter Xu
2019-04-26 4:51 ` [PATCH v4 13/27] mm: introduce do_wp_page_cont() Peter Xu
2019-04-26 4:51 ` [PATCH v4 14/27] userfaultfd: wp: handle COW properly for uffd-wp Peter Xu
2019-04-26 4:51 ` [PATCH v4 15/27] userfaultfd: wp: drop _PAGE_UFFD_WP properly when fork Peter Xu
2019-04-26 4:51 ` [PATCH v4 16/27] userfaultfd: wp: add pmd_swp_*uffd_wp() helpers Peter Xu
2019-04-26 4:51 ` [PATCH v4 17/27] userfaultfd: wp: support swap and page migration Peter Xu
2019-04-26 4:51 ` [PATCH v4 18/27] khugepaged: skip collapse if uffd-wp detected Peter Xu
2019-04-26 4:51 ` [PATCH v4 19/27] userfaultfd: introduce helper vma_find_uffd Peter Xu
2019-04-26 4:51 ` Peter Xu [this message]
2019-04-26 4:51 ` [PATCH v4 21/27] userfaultfd: wp: add the writeprotect API to userfaultfd ioctl Peter Xu
2019-04-26 4:51 ` [PATCH v4 22/27] userfaultfd: wp: enabled write protection in userfaultfd API Peter Xu
2019-04-26 4:51 ` [PATCH v4 23/27] userfaultfd: wp: don't wake up when doing write protect Peter Xu
2019-04-26 4:51 ` [PATCH v4 24/27] userfaultfd: wp: UFFDIO_REGISTER_MODE_WP documentation update Peter Xu
2019-04-26 4:51 ` [PATCH v4 25/27] userfaultfd: wp: declare _UFFDIO_WRITEPROTECT conditionally Peter Xu
2019-04-26 4:51 ` [PATCH v4 26/27] userfaultfd: selftests: refactor statistics Peter Xu
2019-04-26 4:51 ` [PATCH v4 27/27] userfaultfd: selftests: add write-protect test Peter Xu
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