fs: split receive_fd_replace from __receive_fd

receive_fd_replace shares almost no code with the general case, so split
it out.  Also remove the "Bump the sock usage counts" comment from
both copies, as that is now what __receive_sock actually does.

[AV: ... and make the only user of receive_fd_replace() choose between
it and receive_fd() according to what userland had passed to it in
flags]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 19 insertions, 20 deletions

diff --git a/fs/file.c b/fs/file.c
index f3a4bac2cbe9..d8ccb95a7f41 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -1068,8 +1068,6 @@ out_unlock:
 
 /**
  * __receive_fd() - Install received file into file descriptor table
- *
- * @fd: fd to install into (if negative, a new fd will be allocated)
  * @file: struct file that was received from another process
  * @ufd: __user pointer to write new fd number to
  * @o_flags: the O_* flags to apply to the new fd entry
@@ -1083,7 +1081,7 @@ out_unlock:
  *
  * Returns newly install fd or -ve on error.
  */
-int __receive_fd(int fd, struct file *file, int __user *ufd, unsigned int o_flags)
+int __receive_fd(struct file *file, int __user *ufd, unsigned int o_flags)
 {
 	int new_fd;
 	int error;
@@ -1092,32 +1090,33 @@ int __receive_fd(int fd, struct file *file, int __user *ufd, unsigned int o_flag
 	if (error)
 		return error;
 
-	if (fd < 0) {
-		new_fd = get_unused_fd_flags(o_flags);
-		if (new_fd < 0)
-			return new_fd;
-	} else {
-		new_fd = fd;
-	}
+	new_fd = get_unused_fd_flags(o_flags);
+	if (new_fd < 0)
+		return new_fd;
 
 	if (ufd) {
 		error = put_user(new_fd, ufd);
 		if (error) {
-			if (fd < 0)
-				put_unused_fd(new_fd);
+			put_unused_fd(new_fd);
 			return error;
 		}
 	}
 
-	if (fd < 0) {
-		fd_install(new_fd, get_file(file));
-	} else {
-		error = replace_fd(new_fd, file, o_flags);
-		if (error)
-			return error;
-	}
+	fd_install(new_fd, get_file(file));
+	__receive_sock(file);
+	return new_fd;
+}
 
-	/* Bump the sock usage counts, if any. */
+int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags)
+{
+	int error;
+
+	error = security_file_receive(file);
+	if (error)
+		return error;
+	error = replace_fd(new_fd, file, o_flags);
+	if (error)
+		return error;
 	__receive_sock(file);
 	return new_fd;
 }