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=-5.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 F1212C2BA83 for ; Wed, 12 Feb 2020 15:52:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BABF4206D7 for ; Wed, 12 Feb 2020 15:52:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=yahoo.com header.i=@yahoo.com header.b="sT/NjdFV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728596AbgBLPwP (ORCPT ); Wed, 12 Feb 2020 10:52:15 -0500 Received: from sonic307-15.consmr.mail.ne1.yahoo.com ([66.163.190.38]:34593 "EHLO sonic307-15.consmr.mail.ne1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728052AbgBLPwO (ORCPT ); Wed, 12 Feb 2020 10:52:14 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1581522732; bh=4bDYcDU7Mlh6f5S31FmwUTk/wsFQm+13ahLvA0T7G9M=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From:Subject; b=sT/NjdFVI2M2HYotcKH5LgV8HpQBwFK3oN7BjP4LSbhqb/ESgr0O8K7rY3K28GLDwcoIoz7bihE/r/ZBHxzXfQn/D60TamWEvv0xKW0l9wXDSURP/icO155r2bwhwRR1ZFyKIo4At0pRpdV7Ig/DG9bAQXe64Xxc+7BtPUTI+BZLTANbafpvc/5ervpbKpONnwr+0C40UPd7qOd+c833IW0uvPmarsBuPYOrMD2SCJciC2UJtTqLS+Sp4sGpDPG5vs7Bv6o1kJ7gmtlzKKwa9IoYpJDlnLt3m8ZRt6CLIci0saPvGK3XpJqmV1P/Zi1leuaSiRDrUGoDmDAql4IszA== X-YMail-OSG: MZ6b8JMVM1mj8C6.wZxAxcY5SEAf488LG6hoWbNqHvNT9NEAaRUGiBHXwUqQ.7P Ss31bOxqex0COunhZwX3mppFFpAsZuyIJh8nJEFWZj3Ha7020xjesUAx.poNJ7wh9S.utwPru6NP OZqoMl0pOU64X96BQIzz31vaWL0XI4pjrvYVj7wAKMmgHiWroaKq4ma5at8HhdFJ6lUIAId4mwFI Mt48gZMXIQbuPlXFsBC7dsisCE6zh8VFXtbaGwZRK.M5CzIa2pPPkVbdX2kmKGlRe1.8KB5BFkVh CgcQjbA_1p.9Fv1OEuZamMNJW3uZ3_oUmpUQXGytvA2w.Sl1f1kknUsOdtp9eUZYGiFrzjZqCf13 anPtcKrZk0Qx7NoGw9jKcJrcKFbnjGjbcA8g7vrX6h.NLsAMlGZ9IU_HDkmWjl4QVjEKyF85RfxX lsa5D2G9WIrAyFDHvisKglBiWNw8ILc9J2qLK_YfkjjLWdf6IEBShWtRQprH8PSrT21bLXsdCExN dyabnD6Seu8JvWlIgfaOlcHbArI2LnlxpFc0z1o4URrXbQjXkW_LybDJyt_ivhP5iExugowkN9CO StXkh5_bMmyESFNwHBz8MJ05fTGFQJi_OSDlX02etKINeiJ8fEzhcw4lVoihDv._vPRtsyEYMCOY LR05wNApX7IVbR8ok4q9O3MDHXfNR3mcp4QFaghZ40pm1tYIoNvguSKT_GebSXgPwyNR8GH0uA3Y PW2zGtqkNkXiv.DlVPWG60bDlaXNJbjgxPyvxpfWGlH82kLPXyeJbFQCYczefKGt49hTcaaG1vwF AFWhSFmdPRYWHUjTSvFYR4ynTVAg7q6L0HfO63OOJFk0N_9YcSLamW0aJ2d8GlPBmdDh7oCbbdqP 7nTKQb.OuHHbF0oJxPG0FrAhGKuJcJmbpwkL8Z_Aud..L3KBQTgg.HpXV0hCadZ7iZ9kERWKii3D GYxMTwjSlbuyxJskNs4u1idhzWCrEHvxVIY.wk0vbeHS0aqkkWtYh9m2f6nHRa9B5GM8.CprivPd mtBMQnskCnayT_7d9ie4iR.T_qw7BZ4gC5SMOvz2draXHjVAQMRt.dQ7OH4qZUSRhTE7PaIaX9dl pid047U1N81QQHnxD7JV0xpeNMYYZ4uiIiPDXjufM1rMK8AynpC2KwBMAJzhkfZtw4Ygliy6UE4T vFmnFbOMhVYEulvuxh0IMY803TndZo1WZ45pvvo8.KLkcyHu9JXOzxQDHWnXSjCIl_jGKitDWAEm SMnFP.D7pTBuGKrj1PlZW0tOZBwRtldx4LkexDKY.rNSsWupEVpFaqFZKbHgA9c2zkG4ADEXNIAG A9d4kzrMXW0Ch7CixDcOY5ugle3jK34jTysv4e_aZkJfnr6mvQZhAj2z12eRvAlqb4p7SiiqNQpm TZqxS_sFAr7UTPc4XpSNsX55Ht6hEiBcy7Q-- Received: from sonic.gate.mail.ne1.yahoo.com by sonic307.consmr.mail.ne1.yahoo.com with HTTP; Wed, 12 Feb 2020 15:52:12 +0000 Received: by smtp428.mail.ne1.yahoo.com (Oath Hermes SMTP Server) with ESMTPA ID b49c7ee0068c6dfa494419f9447be234; Wed, 12 Feb 2020 15:52:12 +0000 (UTC) Subject: Re: BPF LSM and fexit [was: [PATCH bpf-next v3 04/10] bpf: lsm: Add mutable hooks list for the BPF LSM] To: Alexei Starovoitov , Daniel Borkmann Cc: Jann Horn , KP Singh , kernel list , bpf , linux-security-module , Brendan Jackman , Florent Revest , Thomas Garnier , Alexei Starovoitov , James Morris , Kees Cook , Thomas Garnier , Michael Halcrow , Paul Turner , Brendan Gregg , Matthew Garrett , Christian Brauner , =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= , Florent Revest , Brendan Jackman , "Serge E. Hallyn" , Mauro Carvalho Chehab , "David S. Miller" , Greg Kroah-Hartman , Kernel Team , Casey Schaufler References: <20200211124334.GA96694@google.com> <20200211175825.szxaqaepqfbd2wmg@ast-mbp> <20200211190943.sysdbz2zuz5666nq@ast-mbp> <20200211201039.om6xqoscfle7bguz@ast-mbp> <20200211213819.j4ltrjjkuywihpnv@ast-mbp> <1cd10710-a81b-8f9b-696d-aa40b0a67225@iogearbox.net> <20200212024542.gdsafhvqykucdp4h@ast-mbp> From: Casey Schaufler Autocrypt: addr=casey@schaufler-ca.com; keydata= mQINBFzV9HABEAC/mmv3jeJyF7lR7QhILYg1+PeBLIMZv7KCzBSc/4ZZipoWdmr77Lel/RxQ 1PrNx0UaM5r6Hj9lJmJ9eg4s/TUBSP67mTx+tsZ1RhG78/WFf9aBe8MSXxY5cu7IUwo0J/CG vdSqACKyYPV5eoTJmnMxalu8/oVUHyPnKF3eMGgE0mKOFBUMsb2pLS/enE4QyxhcZ26jeeS6 3BaqDl1aTXGowM5BHyn7s9LEU38x/y2ffdqBjd3au2YOlvZ+XUkzoclSVfSR29bomZVVyhMB h1jTmX4Ac9QjpwsxihT8KNGvOM5CeCjQyWcW/g8LfWTzOVF9lzbx6IfEZDDoDem4+ZiPsAXC SWKBKil3npdbgb8MARPes2DpuhVm8yfkJEQQmuLYv8GPiJbwHQVLZGQAPBZSAc7IidD2zbf9 XAw1/SJGe1poxOMfuSBsfKxv9ba2i8hUR+PH7gWwkMQaQ97B1yXYxVEkpG8Y4MfE5Vd3bjJU kvQ/tOBUCw5zwyIRC9+7zr1zYi/3hk+OG8OryZ5kpILBNCo+aePeAJ44znrySarUqS69tuXd a3lMPHUJJpUpIwSKQ5UuYYkWlWwENEWSefpakFAIwY4YIBkzoJ/t+XJHE1HTaJnRk6SWpeDf CreF3+LouP4njyeLEjVIMzaEpwROsw++BX5i5vTXJB+4UApTAQARAQABtChDYXNleSBTY2hh dWZsZXIgPGNhc2V5QHNjaGF1Zmxlci1jYS5jb20+iQJUBBMBCAA+FiEEC+9tH1YyUwIQzUIe OKUVfIxDyBEFAlzV9HACGwMFCRLMAwAFCwkIBwIGFQoJCAsCBBYCAwECHgECF4AACgkQOKUV fIxDyBG6ag/6AiRl8yof47YOEVHlrmewbpnlBTaYNfJ5cZflNRKRX6t4bp1B2YV1whlDTpiL vNOwFkh+ZE0eI5M4x8Gw2Oiok+4Q5liA9PHTozQYF+Ia+qdL5EehfbLGoEBqklpGvG3h8JsO 7SvONJuFDgvab/U/UriDYycJwzwKZuhVtK9EMpnTtUDyP3DY+Q8h7MWsniNBLVXnh4yBIEJg SSgDn3COpZoFTPGKE+rIzioo/GJe8CTa2g+ZggJiY/myWTS3quG0FMvwvNYvZ4I2g6uxSl7n bZVqAZgqwoTAv1HSXIAn9muwZUJL03qo25PFi2gQmX15BgJKQcV5RL0GHFHRThDS3IyadOgK P2j78P8SddTN73EmsG5OoyzwZAxXfck9A512BfVESqapHurRu2qvMoUkQaW/2yCeRQwGTsFj /rr0lnOBkyC6wCmPSKXe3dT2mnD5KnCkjn7KxLqexKt4itGjJz4/ynD/qh+gL7IPbifrQtVH JI7cr0fI6Tl8V6efurk5RjtELsAlSR6fKV7hClfeDEgLpigHXGyVOsynXLr59uE+g/+InVic jKueTq7LzFd0BiduXGO5HbGyRKw4MG5DNQvC//85EWmFUnDlD3WHz7Hicg95D+2IjD2ZVXJy x3LTfKWdC8bU8am1fi+d6tVEFAe/KbUfe+stXkgmfB7pxqW5Ag0EXNX0cAEQAPIEYtPebJzT wHpKLu1/j4jQcke06Kmu5RNuj1pEje7kX5IKzQSs+CPH0NbSNGvrA4dNGcuDUTNHgb5Be9hF zVqRCEvF2j7BFbrGe9jqMBWHuWheQM8RRoa2UMwQ704mRvKr4sNPh01nKT52ASbWpBPYG3/t WbYaqfgtRmCxBnqdOx5mBJIBh9Q38i63DjQgdNcsTx2qS7HFuFyNef5LCf3jogcbmZGxG/b7 yF4OwmGsVc8ufvlKo5A9Wm+tnRjLr/9Mn9vl5Xa/tQDoPxz26+aWz7j1in7UFzAarcvqzsdM Em6S7uT+qy5jcqyuipuenDKYF/yNOVSNnsiFyQTFqCPCpFihOnuaWqfmdeUOQHCSo8fD4aRF emsuxqcsq0Jp2ODq73DOTsdFxX2ESXYoFt3Oy7QmIxeEgiHBzdKU2bruIB5OVaZ4zWF+jusM Uh+jh+44w9DZkDNjxRAA5CxPlmBIn1OOYt1tsphrHg1cH1fDLK/pDjsJZkiH8EIjhckOtGSb aoUUMMJ85nVhN1EbU/A3DkWCVFEA//Vu1+BckbSbJKE7Hl6WdW19BXOZ7v3jo1q6lWwcFYth esJfk3ZPPJXuBokrFH8kqnEQ9W2QgrjDX3et2WwZFLOoOCItWxT0/1QO4ikcef/E7HXQf/ij Dxf9HG2o5hOlMIAkJq/uLNMvABEBAAGJAjwEGAEIACYWIQQL720fVjJTAhDNQh44pRV8jEPI EQUCXNX0cAIbDAUJEswDAAAKCRA4pRV8jEPIEWkzEACKFUnpp+wIVHpckMfBqN8BE5dUbWJc GyQ7wXWajLtlPdw1nNw0Wrv+ob2RCT7qQlUo6GRLcvj9Fn5tR4hBvR6D3m8aR0AGHbcC62cq I7LjaSDP5j/em4oVL2SMgNTrXgE2w33JMGjAx9oBzkxmKUqprhJomPwmfDHMJ0t7y39Da724 oLPTkQDpJL1kuraM9TC5NyLe1+MyIxqM/8NujoJbWeQUgGjn9uxQAil7o/xSCjrWCP3kZDID vd5ZaHpdl8e1mTExQoKr4EWgaMjmD/a3hZ/j3KfTVNpM2cLfD/QwTMaC2fkK8ExMsz+rUl1H icmcmpptCwOSgwSpPY1Zfio6HvEJp7gmDwMgozMfwQuT9oxyFTxn1X3rn1IoYQF3P8gsziY5 qtTxy2RrgqQFm/hr8gM78RhP54UPltIE96VywviFzDZehMvuwzW//fxysIoK97Y/KBZZOQs+ /T+Bw80Pwk/dqQ8UmIt2ffHEgwCTbkSm711BejapWCfklxkMZDp16mkxSt2qZovboVjXnfuq wQ1QL4o4t1hviM7LyoflsCLnQFJh6RSBhBpKQinMJl/z0A6NYDkQi6vEGMDBWX/M2vk9Jvwa v0cEBfY3Z5oFgkh7BUORsu1V+Hn0fR/Lqq/Pyq+nTR26WzGDkolLsDr3IH0TiAVH5ZuPxyz6 abzjfg== Message-ID: Date: Wed, 12 Feb 2020 07:52:09 -0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200212024542.gdsafhvqykucdp4h@ast-mbp> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Mailer: WebService/1.1.15199 hermes Apache-HttpAsyncClient/4.1.4 (Java/1.8.0_181) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/11/2020 6:45 PM, Alexei Starovoitov wrote: > On Wed, Feb 12, 2020 at 01:09:07AM +0100, Daniel Borkmann wrote: >> Another approach could be to have a special nop inside call_int_hook() >> macro which would then get patched to avoid these situations. Somewhat >> similar like static keys where it could be defined anywhere in text but >> with updating of call_int_hook()'s RC for the verdict. Tell me again why you can't register your BPF hooks like all the other security modules do? You keep reintroducing BPF as a special case, and I don't see why. > Sounds nice in theory. I couldn't quite picture how that would look > in the code, so I hacked: > diff --git a/security/security.c b/security/security.c > index 565bc9b67276..ce4bc1e5e26c 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -28,6 +28,7 @@ > #include > #include > #include > +#include > > #define MAX_LSM_EVM_XATTR 2 > > @@ -678,12 +679,26 @@ static void __init lsm_early_task(struct task_struct *task) > * This is a hook that returns a value. > */ > > +#define LSM_HOOK_NAME(FUNC) \ > + DEFINE_STATIC_KEY_FALSE(bpf_lsm_key_##FUNC); > +#include > +#undef LSM_HOOK_NAME > +__diag_push(); > +__diag_ignore(GCC, 8, "-Wstrict-prototypes", ""); > +#define LSM_HOOK_NAME(FUNC) \ > + int bpf_lsm_call_##FUNC() {return 0;} > +#include > +#undef LSM_HOOK_NAME > +__diag_pop(); > + > #define call_void_hook(FUNC, ...) \ > do { \ > struct security_hook_list *P; \ > \ > hlist_for_each_entry(P, &security_hook_heads.FUNC, list) \ > P->hook.FUNC(__VA_ARGS__); \ > + if (static_branch_unlikely(&bpf_lsm_key_##FUNC)) \ > + (void)bpf_lsm_call_##FUNC(__VA_ARGS__); \ > } while (0) > > #define call_int_hook(FUNC, IRC, ...) ({ \ > @@ -696,6 +711,8 @@ static void __init lsm_early_task(struct task_struct *task) > if (RC != 0) \ > break; \ > } \ > + if (RC == IRC && static_branch_unlikely(&bpf_lsm_key_##FUNC)) \ > + RC = bpf_lsm_call_##FUNC(__VA_ARGS__); \ > } while (0); \ > RC; \ > }) > > The assembly looks good from correctness and performance points. > union security_list_options can be split into lsm_hook_names.h too > to avoid __diag_ignore. Is that what you have in mind? > I don't see how one can improve call_int_hook() macro without > full refactoring of linux/lsm_hooks.h > imo static_key doesn't have to be there in the first set. We can add this > optimization later.