switch kernel_sendmsg() and kernel_recvmsg() to iov_iter_kvec()

For kernel_sendmsg() that eliminates the need to play with setfs();
for kernel_recvmsg() it does *not* - a couple of callers are using
it with non-NULL ->msg_control, which would be treated as userland
address on recvmsg side of things.

In all cases we are really setting a kvec-backed iov_iter, though.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 3 insertions, 17 deletions

diff --git a/net/socket.c b/net/socket.c
index e5669cee0759..b6ceeda65214 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -627,18 +627,8 @@ EXPORT_SYMBOL(sock_sendmsg);
 int kernel_sendmsg(struct socket *sock, struct msghdr *msg,
                    struct kvec *vec, size_t num, size_t size)
 {
-        mm_segment_t oldfs = get_fs();
-        int result;
-
-        set_fs(KERNEL_DS);
-        /*
-         * the following is safe, since for compiler definitions of kvec and
-         * iovec are identical, yielding the same in-core layout and alignment
-         */
-        iov_iter_init(&msg->msg_iter, WRITE, (struct iovec *)vec, num, size);
-        result = sock_sendmsg(sock, msg, size);
-        set_fs(oldfs);
-        return result;
+        iov_iter_kvec(&msg->msg_iter, WRITE | ITER_KVEC, vec, num, size);
+        return sock_sendmsg(sock, msg, size);
 }
 EXPORT_SYMBOL(kernel_sendmsg);
 
@@ -755,12 +745,8 @@ int kernel_recvmsg(struct socket *sock, struct msghdr *msg,
         mm_segment_t oldfs = get_fs();
         int result;
 
+        iov_iter_kvec(&msg->msg_iter, READ | ITER_KVEC, vec, num, size);
         set_fs(KERNEL_DS);
-        /*
-         * the following is safe, since for compiler definitions of kvec and
-         * iovec are identical, yielding the same in-core layout and alignment
-         */
-        iov_iter_init(&msg->msg_iter, READ, (struct iovec *)vec, num, size);
         result = sock_recvmsg(sock, msg, size, flags);
         set_fs(oldfs);
         return result;