VisionFive2 Linux kernel

StarFive Tech Linux Kernel for VisionFive (JH7110) boards (mirror)

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author: Kees Cook <keescook@chromium.org> 2020-06-10 08:46:58 -0700 committer: Kees Cook <keescook@chromium.org> 2020-07-13 11:03:45 -0700 commit: 173817151b15d5a72a9bef1d2df7e6e7f6750f2e parent: 910d2f16ac90463a1f5b03d53246c443e2b354b9
Commit Summary:
fs: Expand __receive_fd() to accept existing fd
Diffstat:
1 file changed, 19 insertions, 6 deletions
diff --git a/fs/file.c b/fs/file.c
index 56d96d5c0c9f..4fb111735d1d 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -939,6 +939,7 @@ 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
@@ -952,7 +953,7 @@ out_unlock:
  *
  * Returns newly install fd or -ve on error.
  */
-int __receive_fd(struct file *file, int __user *ufd, unsigned int o_flags)
+int __receive_fd(int fd, struct file *file, int __user *ufd, unsigned int o_flags)
 {
 	int new_fd;
 	int error;
@@ -961,21 +962,33 @@ int __receive_fd(struct file *file, int __user *ufd, unsigned int o_flags)
 	if (error)
 		return error;
 
-	new_fd = get_unused_fd_flags(o_flags);
-	if (new_fd < 0)
-		return new_fd;
+	if (fd < 0) {
+		new_fd = get_unused_fd_flags(o_flags);
+		if (new_fd < 0)
+			return new_fd;
+	} else {
+		new_fd = fd;
+	}
 
 	if (ufd) {
 		error = put_user(new_fd, ufd);
 		if (error) {
-			put_unused_fd(new_fd);
+			if (fd < 0)
+				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;
+	}
+
 	/* Bump the sock usage counts, if any. */
 	__receive_sock(file);
-	fd_install(new_fd, get_file(file));
 	return new_fd;
 }