From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-3488798-1520562721-2-14185644260681197322 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.25, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='CN', FromHeader='net', MailFrom='org' X-Spam-charsets: X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: linux-api-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1520562721; b=v/eWeOAJC2cmuuoI6xOX8/sgpCAaPJIaxXsE8AuZevD9vqn Zxr3cWUwvSyOuCSg8jJmXC4opUjdXuNDfHmzvIUSoNdYdCbMwZxuwG2+DmIH0ta5 acuU7cNm6vy1tPAlZdkwHeb4h/uFMRkVOKDJWX7KXUjtwbbb5EKTTQePkb4cOIKf t06OIcRF9cvifW5iTpD78CGpVQN/KaVIDhNA5A2Y5Sr1AqyleXzDmzVpCmsTxahG ybrbJuNY30PjWu3nyb1EXMB8ZMxx007v5dYThgfFksxhY30yjCa9tsU5uIB1wtQ+ lK7FWY3qnljQQe1zG4YL6VBkZEwcCxLVJK4XQ3w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=date:message-id:to:cc:subject:from :in-reply-to:references:mime-version:content-type :content-transfer-encoding:sender:list-id; s=arctest; t= 1520562721; bh=rF9Vu5mMEqA0plRW0nRwzdJdoEYOP18DHTD+eoYzkfE=; b=T nhXdRxE2ay5z28WowDCQhyH5Lp1CEsoM7aaVmsZBGkyKFiJffiVgNUQ2KDyAL/ce oxEVBlS2dJVVT48t1GnwOzzdTdBGSDdDpLuW7JgfKbNy65evqnkyR4ZxGfdMDwLu n0cm34LZGmXjB32MNaRAVJRsfVJ4gUNYTcXC3WXWVfyjrpywC+m0pjdFt3oAJvVY YUSTNu277ExtMqirHJrkGS7pgevRI+HifCFm4lNAOWDC3JboxR4qi+guNurH0wh1 1r9YKP9d1bwNBGOi4Q86y4l20nHHlJRdt4fjRPgscKwOSrMxWS3n9jdrqQllwqrs n2xZk30GXAaooMHGhOEsA== ARC-Authentication-Results: i=1; mx5.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=davemloft.net; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-api-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-category=clean score=0 state=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=davemloft.net header.result=pass header_is_org_domain=yes Authentication-Results: mx5.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=davemloft.net; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-api-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-category=clean score=0 state=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=davemloft.net header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751019AbeCICb7 (ORCPT ); Thu, 8 Mar 2018 21:31:59 -0500 Received: from shards.monkeyblade.net ([184.105.139.130]:46172 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750896AbeCICb6 (ORCPT ); Thu, 8 Mar 2018 21:31:58 -0500 Date: Thu, 08 Mar 2018 21:31:53 -0500 (EST) Message-Id: <20180308.213153.2003279953084099668.davem@davemloft.net> To: luto@kernel.org Cc: alexei.starovoitov@gmail.com, keescook@chromium.org, ast@kernel.org, tixxdz@gmail.com, viro@zeniv.linux.org.uk, daniel@iogearbox.net, torvalds@linux-foundation.org, gregkh@linuxfoundation.org, mcgrof@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, linux-api@vger.kernel.org Subject: Re: [PATCH net-next] modules: allow modprobe load regular elf binaries From: David Miller In-Reply-To: References: <20180309012046.6kcivmzzkap3a4xc@ast-mbp> X-Mailer: Mew version 6.7 on Emacs 25.3 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-api-owner@vger.kernel.org X-Mailing-List: linux-api@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: Andy Lutomirski Date: Fri, 9 Mar 2018 02:12:24 +0000 > First, compile your user code and emit a staitc binary. Use objdump > fiddling or a trivial .S file to make that static binary into a > variable. Then write a tiny shim module like this: > > extern unsigned char __begin_user_code[], __end_user_code[]; > > int __init init_shim_module(void) > { > return call_umh_blob(__begin_user_code, __end_user_code - __begin_user_code); > } > > By itself, this is clearly a worse solution than yours, but it has two > benefits, one small and two big. The small benefit is that it is > completely invisible to userspace: the .ko file is a bona fide module. Anything you try to do which makes these binaries "special" is a huge negative. > The big benefits are: I don't see those things as benefits at all, and Alexei's scheme can easily be made to work in your benefit #1 case too. It's a user binary. It's shipped with the kernel and it's signed. If we can't trust that, we can't trust much else. And this whole container argument.. It's a mirage. Kernel modules are 1000 times worse, since they can access any container and any namespace they want.