Commit 130fdbc3 authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

ovl: pass correct flags for opening real directory 



The three instances of ovl_path_open() in overlayfs/readdir.c do three
different things:

 - pass f_flags from overlay file
 - pass O_RDONLY | O_DIRECTORY
 - pass just O_RDONLY

The value of f_flags can be (other than O_RDONLY):

O_WRONLY	- not possible for a directory
O_RDWR		- not possible for a directory
O_CREAT		- masked out by dentry_open()
O_EXCL		- masked out by dentry_open()
O_NOCTTY	- masked out by dentry_open()
O_TRUNC		- masked out by dentry_open()
O_APPEND	- no effect on directory ops
O_NDELAY	- no effect on directory ops
O_NONBLOCK	- no effect on directory ops
__O_SYNC	- no effect on directory ops
O_DSYNC		- no effect on directory ops
FASYNC		- no effect on directory ops
O_DIRECT	- no effect on directory ops
O_LARGEFILE	- ?
O_DIRECTORY	- only affects lookup
O_NOFOLLOW	- only affects lookup
O_NOATIME	- overlay sets this unconditionally in ovl_path_open()
O_CLOEXEC	- only affects fd allocation
O_PATH		- no effect on directory ops
__O_TMPFILE	- not possible for a directory


Fon non-merge directories we use the underlying filesystem's iterate; in
this case honor O_LARGEFILE from the original file to make sure that open
doesn't get rejected.

For merge directories it's safe to pass O_LARGEFILE unconditionally since
userspace will only see the artificial offsets created by overlayfs.

Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 21d8d66a

fs/overlayfs/readdir.c

+9 −3
Original line number Diff line number Diff line
@@ -297,7 +297,7 @@ static inline int ovl_dir_read(struct path *realpath, 
	struct file *realfile;

	int err;



	realfile = ovl_path_open(realpath, O_RDONLY | O_DIRECTORY);

	realfile = ovl_path_open(realpath, O_RDONLY | O_LARGEFILE);

	if (IS_ERR(realfile))

		return PTR_ERR(realfile);
@@ -831,6 +831,12 @@ static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin) 
	return res;

}



static struct file *ovl_dir_open_realfile(struct file *file,

					  struct path *realpath)

{

	return ovl_path_open(realpath, O_RDONLY | (file->f_flags & O_LARGEFILE));

}



static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,

			 int datasync)

{
@@ -853,7 +859,7 @@ static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end, 
			struct path upperpath;



			ovl_path_upper(dentry, &upperpath);

			realfile = ovl_path_open(&upperpath, O_RDONLY);

			realfile = ovl_dir_open_realfile(file, &upperpath);



			inode_lock(inode);

			if (!od->upperfile) {
@@ -904,7 +910,7 @@ static int ovl_dir_open(struct inode *inode, struct file *file) 
		return -ENOMEM;



	type = ovl_path_real(file->f_path.dentry, &realpath);

	realfile = ovl_path_open(&realpath, file->f_flags);

	realfile = ovl_dir_open_realfile(file, &realpath);

	if (IS_ERR(realfile)) {

		kfree(od);

		return PTR_ERR(realfile);