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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>, Andrea Arcangeli <aarcange@redhat.com>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Denis Plotnikov <dplotnikov@virtuozzo.com>,
	Mike Rapoport <rppt@linux.vnet.ibm.com>,
	Marty McFadden <mcfadden8@llnl.gov>, Mel Gorman <mgorman@suse.de>,
	"Kirill A . Shutemov" <kirill@shutemov.name>,
	"Dr . David Alan Gilbert" <dgilbert@redhat.com>
Subject: [PATCH v3 10/28] userfaultfd: wp: add UFFDIO_COPY_MODE_WP
Date: Wed, 20 Mar 2019 10:06:24 +0800	[thread overview]
Message-ID: <20190320020642.4000-11-peterx@redhat.com> (raw)
In-Reply-To: <20190320020642.4000-1-peterx@redhat.com>

From: Andrea Arcangeli <aarcange@redhat.com>

This allows UFFDIO_COPY to map pages write-protected.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
[peterx: switch to VM_WARN_ON_ONCE in mfill_atomic_pte; add brackets
 around "dst_vma->vm_flags & VM_WRITE"; fix wordings in comments and
 commit messages]
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 fs/userfaultfd.c                 |  5 +++--
 include/linux/userfaultfd_k.h    |  2 +-
 include/uapi/linux/userfaultfd.h | 11 +++++-----
 mm/userfaultfd.c                 | 36 ++++++++++++++++++++++----------
 4 files changed, 35 insertions(+), 19 deletions(-)

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index b397bc3b954d..3092885c9d2c 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1683,11 +1683,12 @@ static int userfaultfd_copy(struct userfaultfd_ctx *ctx,
 	ret = -EINVAL;
 	if (uffdio_copy.src + uffdio_copy.len <= uffdio_copy.src)
 		goto out;
-	if (uffdio_copy.mode & ~UFFDIO_COPY_MODE_DONTWAKE)
+	if (uffdio_copy.mode & ~(UFFDIO_COPY_MODE_DONTWAKE|UFFDIO_COPY_MODE_WP))
 		goto out;
 	if (mmget_not_zero(ctx->mm)) {
 		ret = mcopy_atomic(ctx->mm, uffdio_copy.dst, uffdio_copy.src,
-				   uffdio_copy.len, &ctx->mmap_changing);
+				   uffdio_copy.len, &ctx->mmap_changing,
+				   uffdio_copy.mode);
 		mmput(ctx->mm);
 	} else {
 		return -ESRCH;
diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index c6590c58ce28..765ce884cec0 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -34,7 +34,7 @@ extern vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason);
 
 extern 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);
 extern ssize_t mfill_zeropage(struct mm_struct *dst_mm,
 			      unsigned long dst_start,
 			      unsigned long len,
diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h
index 48f1a7c2f1f0..340f23bc251d 100644
--- a/include/uapi/linux/userfaultfd.h
+++ b/include/uapi/linux/userfaultfd.h
@@ -203,13 +203,14 @@ struct uffdio_copy {
 	__u64 dst;
 	__u64 src;
 	__u64 len;
+#define UFFDIO_COPY_MODE_DONTWAKE		((__u64)1<<0)
 	/*
-	 * There will be a wrprotection flag later that allows to map
-	 * pages wrprotected on the fly. And such a flag will be
-	 * available if the wrprotection ioctl are implemented for the
-	 * range according to the uffdio_register.ioctls.
+	 * UFFDIO_COPY_MODE_WP will map the page write protected on
+	 * the fly.  UFFDIO_COPY_MODE_WP is available only if the
+	 * write protected ioctl is implemented for the range
+	 * according to the uffdio_register.ioctls.
 	 */
-#define UFFDIO_COPY_MODE_DONTWAKE		((__u64)1<<0)
+#define UFFDIO_COPY_MODE_WP			((__u64)1<<1)
 	__u64 mode;
 
 	/*
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index d59b5a73dfb3..eaecc21806da 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -25,7 +25,8 @@ 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;
@@ -71,9 +72,9 @@ 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) && !wp_copy)
+		_dst_pte = pte_mkwrite(_dst_pte);
 
 	dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
 	if (dst_vma->vm_file) {
@@ -399,7 +400,8 @@ 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;
 
@@ -416,11 +418,13 @@ 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,
@@ -438,7 +442,8 @@ 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;
@@ -446,6 +451,7 @@ 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:
@@ -502,6 +508,14 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
 	    dst_vma->vm_flags & VM_SHARED))
 		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
 	 */
@@ -557,7 +571,7 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
 		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)) {
@@ -604,14 +618,14 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
 
 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);
 }
-- 
2.17.1


  parent reply	other threads:[~2019-03-20  2:08 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-20  2:06 [PATCH v3 00/28] userfaultfd: write protection support Peter Xu
2019-03-20  2:06 ` [PATCH v3 01/28] mm: gup: rename "nonblocking" to "locked" where proper Peter Xu
2019-03-20  2:06 ` [PATCH v3 02/28] mm: userfault: return VM_FAULT_RETRY on signals Peter Xu
2019-03-20  2:06 ` [PATCH v3 03/28] userfaultfd: don't retake mmap_sem to emulate NOPAGE Peter Xu
2019-03-20  2:06 ` [PATCH v3 04/28] mm: allow VM_FAULT_RETRY for multiple times Peter Xu
2019-04-18 20:11   ` Jerome Glisse
2019-04-19  6:00     ` Peter Xu
2019-03-20  2:06 ` [PATCH v3 05/28] mm: gup: " Peter Xu
2019-03-20  2:06 ` [PATCH v3 06/28] userfaultfd: wp: add helper for writeprotect check Peter Xu
2019-03-20  2:06 ` [PATCH v3 07/28] userfaultfd: wp: hook userfault handler to write protection fault Peter Xu
2019-04-18 20:03   ` Jerome Glisse
2019-03-20  2:06 ` [PATCH v3 08/28] userfaultfd: wp: add WP pagetable tracking to x86 Peter Xu
2019-03-20  2:06 ` [PATCH v3 09/28] userfaultfd: wp: userfaultfd_pte/huge_pmd_wp() helpers Peter Xu
2019-03-20  2:06 ` Peter Xu [this message]
2019-03-20  2:06 ` [PATCH v3 11/28] mm: merge parameters for change_protection() Peter Xu
2019-03-20  2:06 ` [PATCH v3 12/28] userfaultfd: wp: apply _PAGE_UFFD_WP bit Peter Xu
2019-03-20  2:06 ` [PATCH v3 13/28] mm: export wp_page_copy() Peter Xu
2019-03-20  2:06 ` [PATCH v3 14/28] userfaultfd: wp: handle COW properly for uffd-wp Peter Xu
2019-04-18 20:51   ` Jerome Glisse
2019-04-19  6:26     ` Peter Xu
2019-04-19 15:02       ` Jerome Glisse
2019-04-22 12:20         ` Peter Xu
2019-04-22 14:54           ` Jerome Glisse
2019-04-23  3:00             ` Peter Xu
2019-04-23 15:34               ` Jerome Glisse
2019-04-24  8:38                 ` Peter Xu
2019-03-20  2:06 ` [PATCH v3 15/28] userfaultfd: wp: drop _PAGE_UFFD_WP properly when fork Peter Xu
2019-03-20  2:06 ` [PATCH v3 16/28] userfaultfd: wp: add pmd_swp_*uffd_wp() helpers Peter Xu
2019-03-20  2:06 ` [PATCH v3 17/28] userfaultfd: wp: support swap and page migration Peter Xu
2019-04-18 20:59   ` Jerome Glisse
2019-04-19  7:42     ` Peter Xu
2019-04-19 15:08       ` Jerome Glisse
2019-04-22 12:23         ` Peter Xu
2019-03-20  2:06 ` [PATCH v3 18/28] khugepaged: skip collapse if uffd-wp detected Peter Xu
2019-03-20  2:06 ` [PATCH v3 19/28] userfaultfd: introduce helper vma_find_uffd Peter Xu
2019-03-20  2:06 ` [PATCH v3 20/28] userfaultfd: wp: support write protection for userfault vma range Peter Xu
2019-03-20  2:06 ` [PATCH v3 21/28] userfaultfd: wp: add the writeprotect API to userfaultfd ioctl Peter Xu
2019-03-20  2:06 ` [PATCH v3 22/28] userfaultfd: wp: enabled write protection in userfaultfd API Peter Xu
2019-03-22 21:37   ` Mike Rapoport
2019-03-20  2:06 ` [PATCH v3 23/28] userfaultfd: wp: don't wake up when doing write protect Peter Xu
2019-03-20  2:06 ` [PATCH v3 24/28] userfaultfd: wp: UFFDIO_REGISTER_MODE_WP documentation update Peter Xu
2019-03-22 21:46   ` Mike Rapoport
2019-03-20  2:06 ` [PATCH v3 25/28] userfaultfd: wp: fixup swap entries in change_pte_range Peter Xu
2019-04-18 21:01   ` Jerome Glisse
2019-03-20  2:06 ` [PATCH v3 26/28] userfaultfd: wp: declare _UFFDIO_WRITEPROTECT conditionally Peter Xu
2019-03-22 21:43   ` Mike Rapoport
2019-03-20  2:06 ` [PATCH v3 27/28] userfaultfd: selftests: refactor statistics Peter Xu
2019-03-20  2:06 ` [PATCH v3 28/28] userfaultfd: selftests: add write-protect test Peter Xu
2019-04-09  6:08 ` [PATCH v3 00/28] userfaultfd: write protection support Peter Xu
2019-04-18 21:07   ` Jerome Glisse
2019-04-19  7:53     ` Peter Xu

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