Re: [PATCH 16/24] init: add an init_chroot helper

[Al Viro <viro@xxxxxxxxxxxxxxxxxx>]

On Tue, Jul 21, 2020 at 06:28:10PM +0200, Christoph Hellwig wrote:

> +int __init init_chroot(const char *filename)
> +{
> +	struct path path;
> +	int error;
> +
> +	error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
> +	if (error)
> +		return error;
> +	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);

Matter of taste, but if we do that, I wonder if we would be better off with
	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
	if (!error && !ns_capable(current_user_ns(), CAP_SYS_CHROOT))
		error = -EPERM;
	if (!error)
		error = security_path_chroot(&path);
	if (!error)
		set_fs_root(current->fs, &path);
	path_put(&path);
	return error;