[PATCH 1/4] iov: add import_ubuf()

[Keith Busch <kbusch@xxxxxxxx>]

From: Jens Axboe <axboe@xxxxxxxxx>

Like import_single_range(), but for ITER_UBUF.

Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
 include/linux/uio.h |  1 +
 lib/iov_iter.c      | 11 +++++++++++
 2 files changed, 12 insertions(+)

diff --git a/include/linux/uio.h b/include/linux/uio.h
index 2e3134b14ffd..27575495c006 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -337,6 +337,7 @@ ssize_t __import_iovec(int type, const struct iovec __user *uvec,
 		 struct iov_iter *i, bool compat);
 int import_single_range(int type, void __user *buf, size_t len,
 		 struct iovec *iov, struct iov_iter *i);
+int import_ubuf(int type, void __user *buf, size_t len, struct iov_iter *i);
 
 static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
 			void __user *buf, size_t count)
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index c3ca28ca68a6..07adf18e5e40 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1855,6 +1855,17 @@ int import_single_range(int rw, void __user *buf, size_t len,
 }
 EXPORT_SYMBOL(import_single_range);
 
+int import_ubuf(int rw, void __user *buf, size_t len, struct iov_iter *i)
+{
+	if (len > MAX_RW_COUNT)
+		len = MAX_RW_COUNT;
+	if (unlikely(!access_ok(buf, len)))
+		return -EFAULT;
+
+	iov_iter_ubuf(i, rw, buf, len);
+	return 0;
+}
+
 /**
  * iov_iter_restore() - Restore a &struct iov_iter to the same state as when
  *     iov_iter_save_state() was called.
-- 
2.30.2