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

[Al Viro]

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;