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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 830E1C43217 for ; Mon, 21 Nov 2022 17:05:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229750AbiKURF1 (ORCPT ); Mon, 21 Nov 2022 12:05:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55420 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229825AbiKURF0 (ORCPT ); Mon, 21 Nov 2022 12:05:26 -0500 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0372BC846B for ; Mon, 21 Nov 2022 09:05:25 -0800 (PST) Received: from pps.filterd (m0044010.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 2ALGdxqn026447 for ; Mon, 21 Nov 2022 09:05:25 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=facebook; bh=Nbtmoc9lLSKreYlbRoKrmsrKIDLlzBEi1cQlB9kvHQI=; b=Mptv0xi1uWJYlPYu1ns6W5ABNHglokj03ZtQ0lEFrmVrcMVAyroBsTXYa8YoUdqpbZFc K/rRPdrYs4Dxl7nVnxhEs84jEUjkCjUtKEw2xZKNbBSnBnu9mD9M5qq55y3KoEIxmNWs 1/MGjOBDX1AfgF/J8YIER7K7ddbxXU9VOUc= Received: from maileast.thefacebook.com ([163.114.130.3]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3m08k52bm6-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Mon, 21 Nov 2022 09:05:24 -0800 Received: from twshared0705.02.ash8.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 21 Nov 2022 09:05:22 -0800 Received: by devbig309.ftw3.facebook.com (Postfix, from userid 128203) id 6EF841282A557; Mon, 21 Nov 2022 09:05:20 -0800 (PST) From: Yonghong Song To: CC: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , , Martin KaFai Lau , KP Singh Subject: [PATCH bpf-next v7 1/4] compiler_types: Define __rcu as __attribute__((btf_type_tag("rcu"))) Date: Mon, 21 Nov 2022 09:05:20 -0800 Message-ID: <20221121170520.1194669-1-yhs@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20221121170515.1193967-1-yhs@fb.com> References: <20221121170515.1193967-1-yhs@fb.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-ORIG-GUID: cO25crG7wPGtU-2RT_TgqRil23VOFvuy X-Proofpoint-GUID: cO25crG7wPGtU-2RT_TgqRil23VOFvuy X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-11-21_14,2022-11-18_01,2022-06-22_01 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Currently, without rcu attribute info in BTF, the verifier treats rcu tagged pointer as a normal pointer. This might be a problem for sleepable program where rcu_read_lock()/unlock() is not available. For example, for a sleepable fentry program, if rcu protected memory access is interleaved with a sleepable helper/kfunc, it is possible the memory access after the sleepable helper/kfunc might be invalid since the object might have been freed then. To prevent such cases, introducing rcu tagging for memory accesses in verifier can help to reject such programs. To enable rcu tagging in BTF, during kernel compilation, define __rcu as attribute btf_type_tag("rcu") so __rcu information can be preserved in dwarf and btf, and later can be used for bpf prog verific= ation. Acked-by: KP Singh Signed-off-by: Yonghong Song --- include/linux/compiler_types.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/include/linux/compiler_types.h b/include/linux/compiler_type= s.h index eb0466236661..7c1afe0f4129 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -49,7 +49,8 @@ static inline void __chk_io_ptr(const volatile void __i= omem *ptr) { } # endif # define __iomem # define __percpu BTF_TYPE_TAG(percpu) -# define __rcu +# define __rcu BTF_TYPE_TAG(rcu) + # define __chk_user_ptr(x) (void)0 # define __chk_io_ptr(x) (void)0 /* context/locking */ --=20 2.30.2