From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 48D00C43331 for ; Fri, 27 Mar 2020 13:42:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1B65620658 for ; Fri, 27 Mar 2020 13:42:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=tycho.nsa.gov header.i=@tycho.nsa.gov header.b="g9btz5ne" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726656AbgC0Nmc (ORCPT ); Fri, 27 Mar 2020 09:42:32 -0400 Received: from UPDC19PA23.eemsg.mail.mil ([214.24.27.198]:12045 "EHLO UPDC19PA23.eemsg.mail.mil" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726540AbgC0Nmc (ORCPT ); Fri, 27 Mar 2020 09:42:32 -0400 X-EEMSG-check-017: 71368882|UPDC19PA23_ESA_OUT05.csd.disa.mil X-IronPort-AV: E=Sophos;i="5.72,312,1580774400"; d="scan'208";a="71368882" Received: from emsm-gh1-uea11.ncsc.mil ([214.29.60.3]) by UPDC19PA23.eemsg.mail.mil with ESMTP/TLS/DHE-RSA-AES256-SHA256; 27 Mar 2020 13:42:28 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tycho.nsa.gov; i=@tycho.nsa.gov; q=dns/txt; s=tycho.nsa.gov; t=1585316549; x=1616852549; h=subject:to:cc:references:from:message-id:date: mime-version:in-reply-to:content-transfer-encoding; bh=EluxbPINP69ahvzM5QR7sPRQweHHFIS2OjUyuJ8MGO8=; b=g9btz5neRwCNeNvrhumA11va9WhAVrZLctT58YZLVotp3VB3lmOYsq3O V8rAX8AmgVLkNTzhw6Q30a/TGFSsWmk17Isyi5jml3z9aA3HUiUZ+8zwY eLyI1m966FpJYOLHuKOe95WZWtAXhXdfWiHUaJPg71uCoupmKsWDzGphQ MfVsu4rYnncYf+8vmy8L86zihRCe9GeUj68vpxbEt8xjyE2G1dZy6n2HT cHqEYQyaxJ+ZJG3y3WVFq/SGgxxu4F6Ajbwcewn/EGHBFVWqo/JxiXAgh p6ag0EXaKVwubwgIDW9CwE3gEFP47RygYzzYgZ9+zvHyKXUE7ryAYrnJG g==; X-IronPort-AV: E=Sophos;i="5.72,312,1580774400"; d="scan'208";a="41132559" IronPort-PHdr: =?us-ascii?q?9a23=3A+wouJR1LxFUSBm5msmDT+DRfVm0co7zxezQtwd?= =?us-ascii?q?8ZsesQI/XxwZ3uMQTl6Ol3ixeRBMOHsq4C0reH+P26EUU7or+/81k6OKRWUB?= =?us-ascii?q?EEjchE1ycBO+WiTXPBEfjxciYhF95DXlI2t1uyMExSBdqsLwaK+i764jEdAA?= =?us-ascii?q?jwOhRoLerpBIHSk9631+ev8JHPfglEnjWwba59IRmssAncts0bjYRiJ6ov1x?= =?us-ascii?q?DEvmZGd+NKyGxnIl6egwzy7dqq8p559CRQtfMh98peXqj/Yq81U79WAik4Pm?= =?us-ascii?q?4s/MHkugXNQgWJ5nsHT2UZiQFIDBTf7BH7RZj+rC33vfdg1SaAPM32Sbc0WS?= =?us-ascii?q?m+76puVRTlhjsLOyI//WrKkcF7kr5Vrwy9qBx+247UYZ+aNPxifqPGYNgWQX?= =?us-ascii?q?NNUttNWyBdB4+xaYUAD/AFPe1FsYfzoVUApga6CQW1Cu7izjpEi3nr1qM4zu?= =?us-ascii?q?shCxnL0hE+EdIAsHrar9v7O6kdXu+30KbGwi7Ob+9V1Drn9ITEbh4srPOKUL?= =?us-ascii?q?ltccTR004vFwbdg1uNtYzqISuV1uQTvGid8uFuSOevhHQjqwF1vDeuxtonh4?= =?us-ascii?q?7Sho0I0VDJ7jl5wYYpKt24T053e9ikEIBKuC2AOIt2Rd0iTnhutS0nxLMGvp?= =?us-ascii?q?u7czILyJQh3xPfaOKIc5KO4h39UOadOzB4hGhqeL+5mh288lCgx/XhWsS731?= =?us-ascii?q?tGtCpInsTWunwT2BHf9NKLRuZ780y8wziAzRrT5ftBIU0skKrbLIMuzaAom5?= =?us-ascii?q?oItETDAjf2mELrjK+Kbkkk+van6+DgYrj+up+TLZV0igDjMqQ1gMC/HeQ5PR?= =?us-ascii?q?QOX2ic4+i80qHs/VblT7lQi/02k63ZvIjbJcQduKG5HxdY3pss5huwFTur0M?= =?us-ascii?q?kUkWMZIF9KZh6LlZXlN0nLIP/iDPe/h1qskC1sx/DDJrDhGYjCLmPYnbf9fb?= =?us-ascii?q?dy905cyA0pwdBZ/JJbEKsNIP30Wk/vrNDYFAM2MxSow+b7D9VwzoAeWXqUAq?= =?us-ascii?q?+YNqPSvl+I6/kzLOmMfo8VvzP9K/k45/7rl3M5nkUdfaax15sNdH+4BuhmI1?= =?us-ascii?q?meYXf0gNcBFGAKvhAkTOzrk12PSjhTaGy3X60i5zE3EoWmDZ3MRoq1mryOwD?= =?us-ascii?q?+7HoFKZmBBEl2MFXbod4OZW/YDcS6SIdFukiYCVbe/T48szg+utADkxLp9NO?= =?us-ascii?q?bU+TMXtYjl1Ndr4+3fjxYy9SZ7D86FyWGCU3l0nn8URz8xxK1wulR9ylmY3K?= =?us-ascii?q?hmjPxXC8ZT6+lKUggkL57cyfJ1C9ToVgLGZNeJR06sQs+6DjEpUtIx39gObl?= =?us-ascii?q?55G9WjiBDDwiWrD6YOl7OVGJM077jc33ntJ8d90nrG0a4hgEQ7QstLK2Krnb?= =?us-ascii?q?B/9wfNCI7TiUmZlLildb4a3CHT8GeP122OvFtXUARoS6XKQWgfZlfKrdT+/k?= =?us-ascii?q?7CTaWhBqgkMgtE08GCLLBFZ8bmjVVBQ/fjN9DebHyrl2isAhaIw6uGbJD2dG?= =?us-ascii?q?UFwCXdFE8EnhgJ/XmYKwgxGDyho37FATxhElLvZEzs8e1gp3+hUkA0yASKZV?= =?us-ascii?q?V717Wp4h4VmeCcS/QL070eoychty55HFWj0NLMDdqPuQ5hcL9bYdMn71dNzX?= =?us-ascii?q?jZuBBlPpy8M6BigUYTfBltsEPo1hV4FIFAnNMrrHMtwwp9N7iX0ElaeDOf0p?= =?us-ascii?q?H8ILvXJXfu/Bq3ca7Zxkne0MqK+qcI8Pk4qEvssx+yFkU+9HVn1NpV3mCA6Z?= =?us-ascii?q?XKFgoSVpfxUkcq9xh/vb3aZTM954zM3312Laa0qiPC284uBOY90hagfctfPb?= =?us-ascii?q?iLFA/1FM0aCMyuJ/Iwl1e1aRIEOfhY9LQoMMO+a/uGxKmrMf5inD28i2RH5o?= =?us-ascii?q?B931mD9yp7Te7I0JIFzO+C0gSbUDf8iU+rstrrloBceTESAm2/xDD+BIFPeK?= =?us-ascii?q?19Y50LCXu1LsKrxtV+nZntW3tZ9F6+AlMKwsipeQCdb1blxw1fyVwXoWC7mS?= =?us-ascii?q?u/1zF0kSsmobac3CzL2evicgEIN3VXS2lil1fsJo20j9EHXEitdQQpkwGl5U?= =?us-ascii?q?nizahBuKt/N3XTQVtPfyXuIGFiSLW/trWBY85P854otSRXUOKhYVGVRL79pA?= =?us-ascii?q?Ya0yX+EGRE2DA7djaqupPjkxx9kmKdI255rGDFdsFo2Rff+NvcSOZJ3jUcWS?= =?us-ascii?q?l4jSLaBkCmMNm0+dWYjpLDsue5V2K7SJJfazXkzYSFtHjz2Wo/IiX3pPG1ld?= =?us-ascii?q?2vRQsiyi792NlCXiXSqxP9f4yt0L61Z7FJZE5tUWTg5tJ6F4c2qY45gJUdyD?= =?us-ascii?q?BOnZmO1WYWmmf0d9NA0OTxa2RbFm1D+MLc/AWwgB4rFXmO3Y+sEyzGk8Y=3D?= X-IPAS-Result: =?us-ascii?q?A2AGAQA4An5e/wHyM5BmHAEBAQEBBwEBEQEEBAEBgWoEA?= =?us-ascii?q?QELAYF8LGxUATIqhBqOfFIBAQaBCi2Je5FNCgEBAQEBAQEBASsJAQIEAQGER?= =?us-ascii?q?AKCMSQ3Bg4CEAEBAQUBAQEBAQUDAQFshVYMgjspAYMMAQUjDwEFQRALGAICJ?= =?us-ascii?q?gICVwYNBgIBAYJjPwGCVyUPrECBMoQ1AYEVg2uBOAaBDioBjC4aeYEHgREnD?= =?us-ascii?q?4JePoJOhRKCXgSQOV2fR4JGglaFCY8nBh2baZgmlHgjgVgrCAIYCCEPgygSP?= =?us-ascii?q?RgNlySFXSUDMgGBAwEBjX4BAQ?= Received: from tarius.tycho.ncsc.mil ([144.51.242.1]) by emsm-gh1-uea11.NCSC.MIL with ESMTP; 27 Mar 2020 13:42:25 +0000 Received: from moss-pluto.infosec.tycho.ncsc.mil (moss-pluto.infosec.tycho.ncsc.mil [192.168.25.131]) by tarius.tycho.ncsc.mil (8.14.7/8.14.4) with ESMTP id 02RDglU2212485; Fri, 27 Mar 2020 09:42:47 -0400 Subject: Re: [PATCH bpf-next v7 4/8] bpf: lsm: Implement attach, detach and execution To: KP Singh Cc: James Morris , linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-security-module@vger.kernel.org, Brendan Jackman , Florent Revest , Alexei Starovoitov , Daniel Borkmann , Kees Cook , Paul Turner , Jann Horn , Florent Revest , Brendan Jackman , Greg Kroah-Hartman , Paul Moore References: <20200326142823.26277-1-kpsingh@chromium.org> <20200326142823.26277-5-kpsingh@chromium.org> <2241c806-65c9-68f5-f822-9a245ecf7ba0@tycho.nsa.gov> <20200327124115.GA8318@chromium.org> From: Stephen Smalley Message-ID: <14ff822f-3ca5-7ebb-3df6-dd02249169d2@tycho.nsa.gov> Date: Fri, 27 Mar 2020 09:43:45 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200327124115.GA8318@chromium.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: On 3/27/20 8:41 AM, KP Singh wrote: > On 27-Mär 08:27, Stephen Smalley wrote: >> On 3/26/20 8:24 PM, James Morris wrote: >>> On Thu, 26 Mar 2020, KP Singh wrote: >>> >>>> +int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog, >>>> + const struct bpf_prog *prog) >>>> +{ >>>> + /* Only CAP_MAC_ADMIN users are allowed to make changes to LSM hooks >>>> + */ >>>> + if (!capable(CAP_MAC_ADMIN)) >>>> + return -EPERM; >>>> + >>> >>> Stephen, can you confirm that your concerns around this are resolved >>> (IIRC, by SELinux implementing a bpf_prog callback) ? >> >> I guess the only residual concern I have is that CAP_MAC_ADMIN means >> something different to SELinux (ability to get/set file security contexts >> unknown to the currently loaded policy), so leaving the CAP_MAC_ADMIN check >> here (versus calling a new security hook here and checking CAP_MAC_ADMIN in >> the implementation of that hook for the modules that want that) conflates >> two very different things. Prior to this patch, there are no users of >> CAP_MAC_ADMIN outside of individual security modules; it is only checked in >> module-specific logic within apparmor, safesetid, selinux, and smack, so the >> meaning was module-specific. > > As we had discussed, We do have a security hook as well: > > https://lore.kernel.org/bpf/20200324180652.GA11855@chromium.org/ > > The bpf_prog hook which can check for BPF_PROG_TYPE_LSM and implement > module specific logic for LSM programs. I thougt that was okay? > > Kees was in favor of keeping the CAP_MAC_ADMIN check here: > > https://lore.kernel.org/bpf/202003241133.16C02BE5B@keescook > > If you feel strongly and Kees agrees, we can remove the CAP_MAC_ADMIN > check here, but given that we already have a security hook that meets > the requirements, we probably don't need another one. I would favor removing the CAP_MAC_ADMIN check here, and implementing it in a bpf_prog hook for Smack and AppArmor if they want that. SELinux would implement its own check in its existing bpf_prog hook.