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>

diff --git a/net/socket.c b/net/socket.c
index e5669cee0759b3df20b1309d697e31815b19e0a0..b6ceeda65214c9458a8dbc1fd52f27c4bb1a0c79 100644 (file)
--- 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;