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Subject[PATCH V7 -next 04/33] iov_iter: add __iovec_copy_to_user()
Date
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@oracle.com>
---
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 cd85051..3e60370 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -295,7 +295,9 @@ 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);
--
1.8.1.5


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