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 6A30FC4332F for ; Thu, 17 Nov 2022 04:28:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239173AbiKQE2n (ORCPT ); Wed, 16 Nov 2022 23:28:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49308 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239175AbiKQE2k (ORCPT ); Wed, 16 Nov 2022 23:28:40 -0500 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5E619209B9 for ; Wed, 16 Nov 2022 20:28:39 -0800 (PST) Received: from pps.filterd (m0044012.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 2AH4BwWf012268 for ; Wed, 16 Nov 2022 20:28:39 -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=PqdqkRg0YyxoVmQ/coudgYgJ81OG2Nd34rn/j5I0Z3QHTYbZvR6PA5PxAxc993GBxD2I 4VF9nvr4+6+THvIj8ouyjf8csG2Nb8jRl4bL0ctn2hgwl2zs6sG6bQizzGz4ELaj8uIl QcOP8GCUVtGA9NXY3GWSSiglYBZ6QGsXuVs= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3kwdqa82an-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Wed, 16 Nov 2022 20:28:39 -0800 Received: from twshared14438.02.ash8.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:82::c) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Wed, 16 Nov 2022 20:28:37 -0800 Received: by devbig309.ftw3.facebook.com (Postfix, from userid 128203) id 56B2712486029; Wed, 16 Nov 2022 20:28:23 -0800 (PST) From: Yonghong Song To: CC: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , , Martin KaFai Lau , KP Singh Subject: [PATCH bpf-next v6 1/7] compiler_types: Define __rcu as __attribute__((btf_type_tag("rcu"))) Date: Wed, 16 Nov 2022 20:28:23 -0800 Message-ID: <20221117042823.1088167-1-yhs@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20221117042818.1086954-1-yhs@fb.com> References: <20221117042818.1086954-1-yhs@fb.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-GUID: xo7tFJ8vIPv8dyF0-A-0yr2USOPNNU5r X-Proofpoint-ORIG-GUID: xo7tFJ8vIPv8dyF0-A-0yr2USOPNNU5r 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=2022-11-16_03,2022-11-16_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