linux-kernel - Re: [PATCH v2 03/18] ovl: stack miscattr ops

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Date:   Wed, 24 Mar 2021 05:09:59 +0000
From:   Al Viro <viro@...iv.linux.org.uk>
To:     Miklos Szeredi <mszeredi@...hat.com>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH v2 03/18] ovl: stack miscattr ops

On Mon, Mar 22, 2021 at 03:49:01PM +0100, Miklos Szeredi wrote:

> +int ovl_miscattr_set(struct user_namespace *mnt_userns,
> +		     struct dentry *dentry, struct miscattr *ma)
> +{
> +	struct inode *inode = d_inode(dentry);
> +	struct dentry *upperdentry;
> +	const struct cred *old_cred;
> +	int err;
> +
> +	err = ovl_want_write(dentry);
> +	if (err)
> +		goto out;
> +
> +	err = ovl_copy_up(dentry);
> +	if (!err) {
> +		upperdentry = ovl_dentry_upper(dentry);
> +
> +		old_cred = ovl_override_creds(inode->i_sb);
> +		err = ovl_security_miscattr(dentry, ma, true);
> +		if (!err)
> +			err = vfs_miscattr_set(&init_user_ns, upperdentry, ma);
> +		revert_creds(old_cred);
> +		ovl_copyflags(ovl_inode_real(inode), inode);
> +	}
> +	ovl_drop_write(dentry);
> +out:
> +	return err;
> +}

Umm...  No equivalents of
        /*  
         * Prevent copy up if immutable and has no CAP_LINUX_IMMUTABLE
         * capability.
         */ 
        ret = -EPERM;
        if (!ovl_has_upperdata(inode) && IS_IMMUTABLE(inode) &&
            !capable(CAP_LINUX_IMMUTABLE))
                goto unlock;

        ret = ovl_maybe_copy_up(file_dentry(file), O_WRONLY);
        if (ret)
                goto unlock;
in the current tree?