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Commit 7764235b authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

ovl: use vfs_get_link() 



Resulting in a complete removal of a function basically implementing the
inverse of vfs_readlink().

As a bonus, now the proper security hook is also called.

Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent d60874cd

fs/overlayfs/copy_up.c

+6 −40
Original line number Diff line number Diff line
@@ -177,40 +177,6 @@ static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len) 
	return error;

}



static char *ovl_read_symlink(struct dentry *realdentry)

{

	int res;

	char *buf;

	struct inode *inode = realdentry->d_inode;

	mm_segment_t old_fs;



	res = -EINVAL;

	if (!inode->i_op->readlink)

		goto err;



	res = -ENOMEM;

	buf = (char *) __get_free_page(GFP_KERNEL);

	if (!buf)

		goto err;



	old_fs = get_fs();

	set_fs(get_ds());

	/* The cast to a user pointer is valid due to the set_fs() */

	res = inode->i_op->readlink(realdentry,

				    (char __user *)buf, PAGE_SIZE - 1);

	set_fs(old_fs);

	if (res < 0) {

		free_page((unsigned long) buf);

		goto err;

	}

	buf[res] = '\0';



	return buf;



err:

	return ERR_PTR(res);

}



static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)

{

	struct iattr attr = {
@@ -342,18 +308,20 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir, 
int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,

		    struct path *lowerpath, struct kstat *stat)

{

	DEFINE_DELAYED_CALL(done);

	struct dentry *workdir = ovl_workdir(dentry);

	int err;

	struct kstat pstat;

	struct path parentpath;

	struct dentry *lowerdentry = lowerpath->dentry;

	struct dentry *upperdir;

	struct dentry *upperdentry;

	char *link = NULL;

	const char *link = NULL;



	if (WARN_ON(!workdir))

		return -EROFS;



	ovl_do_check_copy_up(lowerpath->dentry);

	ovl_do_check_copy_up(lowerdentry);



	ovl_path_upper(parent, &parentpath);

	upperdir = parentpath.dentry;
@@ -363,7 +331,7 @@ int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, 
		return err;



	if (S_ISLNK(stat->mode)) {

		link = ovl_read_symlink(lowerpath->dentry);

		link = vfs_get_link(lowerdentry, &done);

		if (IS_ERR(link))

			return PTR_ERR(link);

	}
@@ -388,9 +356,7 @@ int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, 
	}

out_unlock:

	unlock_rename(workdir, upperdir);



	if (link)

		free_page((unsigned long) link);

	do_delayed_call(&done);



	return err;

}

fs/overlayfs/inode.c

+1 −9
Original line number Diff line number Diff line
@@ -156,22 +156,14 @@ static const char *ovl_get_link(struct dentry *dentry, 
				struct inode *inode,

				struct delayed_call *done)

{

	struct dentry *realdentry;

	struct inode *realinode;

	const struct cred *old_cred;

	const char *p;



	if (!dentry)

		return ERR_PTR(-ECHILD);



	realdentry = ovl_dentry_real(dentry);

	realinode = realdentry->d_inode;



	if (WARN_ON(!realinode->i_op->get_link))

		return ERR_PTR(-EPERM);



	old_cred = ovl_override_creds(dentry->d_sb);

	p = realinode->i_op->get_link(realdentry, realinode, done);

	p = vfs_get_link(ovl_dentry_real(dentry), done);

	revert_creds(old_cred);

	return p;

}