net: Split a __sys_bind helper for io_uring

io_uring holds a reference to the file and maintains a
sockaddr_storage address.  Similarly to what was done to
__sys_connect_file, split an internal helper for __sys_bind in
preparation to supporting an io_uring bind command.

Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20240614163047.31581-1-krisman@suse.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

include/linux/socket.h

@@ -442,6 +442,8 @@ extern int __sys_accept4(int fd, struct sockaddr __user *upeer_sockaddr,
 extern int __sys_socket(int family, int type, int protocol);
 extern struct file *__sys_socket_file(int family, int type, int protocol);
 extern int __sys_bind(int fd, struct sockaddr __user *umyaddr, int addrlen);
+extern int __sys_bind_socket(struct socket *sock, struct sockaddr_storage *address,
+			     int addrlen);
 extern int __sys_connect_file(struct file *file, struct sockaddr_storage *addr,
 			      int addrlen, int file_flags);
 extern int __sys_connect(int fd, struct sockaddr __user *uservaddr,

net/socket.c

@@ -1822,6 +1822,20 @@ SYSCALL_DEFINE4(socketpair, int, family, int, type, int, protocol,
 	return __sys_socketpair(family, type, protocol, usockvec);
 }
 
+int __sys_bind_socket(struct socket *sock, struct sockaddr_storage *address,
+		      int addrlen)
+{
+	int err;
+
+	err = security_socket_bind(sock, (struct sockaddr *)address,
+				   addrlen);
+	if (!err)
+		err = READ_ONCE(sock->ops)->bind(sock,
+						 (struct sockaddr *)address,
+						 addrlen);
+	return err;
+}
+
 /*
  *	Bind a name to a socket. Nothing much to do here since it's
  *	the protocol's responsibility to handle the local address.
@@ -1839,15 +1853,8 @@ int __sys_bind(int fd, struct sockaddr __user *umyaddr, int addrlen)
 	sock = sockfd_lookup_light(fd, &err, &fput_needed);
 	if (sock) {
 		err = move_addr_to_kernel(umyaddr, addrlen, &address);
-		if (!err) {
-			err = security_socket_bind(sock,
-						   (struct sockaddr *)&address,
-						   addrlen);
-			if (!err)
-				err = READ_ONCE(sock->ops)->bind(sock,
-						      (struct sockaddr *)
-						      &address, addrlen);
-		}
+		if (!err)
+			err = __sys_bind_socket(sock, &address, addrlen);
 		fput_light(sock->file, fput_needed);
 	}
 	return err;