[PATCH V8 04/33] iov_iter: add __iovec_copy_to_user()

[Dave Kleikamp]

This patch adds __iovec_copy_to_user() which doesn't verify write access
to the user memory to be called from code where that verification has
already been done.

Signed-off-by: Dave Kleikamp <dave.kleikamp@xxxxxxxxxx>
---
 fs/iov-iter.c      | 14 ++++++++++++--
 include/linux/fs.h |  4 +++-
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/fs/iov-iter.c b/fs/iov-iter.c
index 0b2407e..6cecab4 100644
--- a/fs/iov-iter.c
+++ b/fs/iov-iter.c
@@ -19,7 +19,7 @@ static size_t __iovec_copy_to_user(char *vaddr, const struct iovec *iov,
 		if (atomic)
 			left = __copy_to_user_inatomic(buf, vaddr, copy);
 		else
-			left = copy_to_user(buf, vaddr, copy);
+			left = __copy_to_user(buf, vaddr, copy);
 		copied += copy;
 		bytes -= copy;
 		vaddr += copy;
@@ -65,7 +65,7 @@ EXPORT_SYMBOL(iov_iter_copy_to_user_atomic);
  * The difference is that it attempts to resolve faults.
  * Page must not be locked.
  */
-size_t iov_iter_copy_to_user(struct page *page,
+size_t __iov_iter_copy_to_user(struct page *page,
 		struct iov_iter *i, unsigned long offset, size_t bytes)
 {
 	char *kaddr;
@@ -84,6 +84,16 @@ size_t iov_iter_copy_to_user(struct page *page,
 	kunmap(page);
 	return copied;
 }
+EXPORT_SYMBOL(__iov_iter_copy_to_user);
+
+size_t iov_iter_copy_to_user(struct page *page,
+		struct iov_iter *i, unsigned long offset, size_t bytes)
+{
+	might_sleep();
+	if (generic_segment_checks(i->iov, &i->nr_segs, &bytes, VERIFY_WRITE))
+		return 0;
+	return __iov_iter_copy_to_user(page, i, offset, bytes);
+}
 EXPORT_SYMBOL(iov_iter_copy_to_user);
 
 static size_t __iovec_copy_from_user(char *vaddr, const struct iovec *iov,
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 80f71df..bfc6eb0 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -296,7 +296,9 @@ struct iov_iter {
 	size_t count;
 };
 
-size_t iov_iter_copy_to_user_atomic(struct page *page,
+size_t __iov_iter_copy_to_user_atomic(struct page *page,
+		struct iov_iter *i, unsigned long offset, size_t bytes);
+size_t __iov_iter_copy_to_user(struct page *page,
 		struct iov_iter *i, unsigned long offset, size_t bytes);
 size_t iov_iter_copy_to_user(struct page *page,
 		struct iov_iter *i, unsigned long offset, size_t bytes);
-- 
1.8.3.4

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