[PATCH v2 1/2] fs: support O_PATH fds with FSCONFIG_SET_FD

[Christian Brauner <brauner@kernel.org>]

Let FSCONFIG_SET_FD handle O_PATH file descriptors. This is particularly
useful in the context of overlayfs where layers can be specified via
file descriptors instead of paths. But userspace must currently use
non-O_PATH file desriptors which is often pointless especially if
the file descriptors have been created via open_tree(OPEN_TREE_CLONE).

Fixes: a08557d19ef41 ("ovl: specify layers via file descriptors")
Signed-off-by: Christian Brauner <brauner@kernel.org>
---
 fs/autofs/autofs_i.h | 2 ++
 fs/fsopen.c          | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/autofs/autofs_i.h b/fs/autofs/autofs_i.h
index 77c7991d89aa..23cea74f9933 100644
--- a/fs/autofs/autofs_i.h
+++ b/fs/autofs/autofs_i.h
@@ -218,6 +218,8 @@ void autofs_clean_ino(struct autofs_info *);
 
 static inline int autofs_check_pipe(struct file *pipe)
 {
+	if (pipe->f_mode & FMODE_PATH)
+		return -EINVAL;
 	if (!(pipe->f_mode & FMODE_CAN_WRITE))
 		return -EINVAL;
 	if (!S_ISFIFO(file_inode(pipe)->i_mode))
diff --git a/fs/fsopen.c b/fs/fsopen.c
index 094a7f510edf..1aaf4cb2afb2 100644
--- a/fs/fsopen.c
+++ b/fs/fsopen.c
@@ -453,7 +453,7 @@ SYSCALL_DEFINE5(fsconfig,
 	case FSCONFIG_SET_FD:
 		param.type = fs_value_is_file;
 		ret = -EBADF;
-		param.file = fget(aux);
+		param.file = fget_raw(aux);
 		if (!param.file)
 			goto out_key;
 		param.dirfd = aux;

-- 
2.47.2