file: stop exposing receive_fd_user()

Not every subsystem needs to have their own specialized helper.
Just us the __receive_fd() helper.

Link: https://lore.kernel.org/r/20231130-vfs-files-fixes-v1-4-e73ca6f4ea83@kernel.orgReviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>

include/linux/file.h

@@ -101,13 +101,6 @@ extern int __receive_fd(struct file *file, int __user *ufd,
 
 extern int receive_fd(struct file *file, unsigned int o_flags);
 
-static inline int receive_fd_user(struct file *file, int __user *ufd,
-				  unsigned int o_flags)
-{
-	if (ufd == NULL)
-		return -EFAULT;
-	return __receive_fd(file, ufd, o_flags);
-}
 int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags);
 
 extern void flush_delayed_fput(void);

include/net/scm.h

@@ -5,6 +5,7 @@
 #include <linux/limits.h>
 #include <linux/net.h>
 #include <linux/cred.h>
+#include <linux/file.h>
 #include <linux/security.h>
 #include <linux/pid.h>
 #include <linux/nsproxy.h>
@@ -208,5 +209,13 @@ static inline void scm_recv_unix(struct socket *sock, struct msghdr *msg,
 	scm_destroy_cred(scm);
 }
 
+static inline int scm_recv_one_fd(struct file *f, int __user *ufd,
+				  unsigned int flags)
+{
+	if (!ufd)
+		return -EFAULT;
+	return __receive_fd(f, ufd, flags);
+}
+
 #endif /* __LINUX_NET_SCM_H */
 

net/compat.c

@@ -297,7 +297,7 @@ void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm)
 	int err = 0, i;
 
 	for (i = 0; i < fdmax; i++) {
-		err = receive_fd_user(scm->fp->fp[i], cmsg_data + i, o_flags);
+		err = scm_recv_one_fd(scm->fp->fp[i], cmsg_data + i, o_flags);
 		if (err < 0)
 			break;
 	}

net/core/scm.c

@@ -319,7 +319,7 @@ void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
 	}
 
 	for (i = 0; i < fdmax; i++) {
-		err = receive_fd_user(scm->fp->fp[i], cmsg_data + i, o_flags);
+		err = scm_recv_one_fd(scm->fp->fp[i], cmsg_data + i, o_flags);
 		if (err < 0)
 			break;
 	}