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 9E90CC4332F for ; Tue, 22 Nov 2022 19:53:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234662AbiKVTx5 (ORCPT ); Tue, 22 Nov 2022 14:53:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39890 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234498AbiKVTxm (ORCPT ); Tue, 22 Nov 2022 14:53:42 -0500 Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 37A57A1A37 for ; Tue, 22 Nov 2022 11:53:37 -0800 (PST) Received: from pps.filterd (m0109331.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 2AMFnQhg019838 for ; Tue, 22 Nov 2022 11:53:36 -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=W/SYxKHs49J6m6oypMnefrlZLLf4WU6oDTfgpYHGttBpPv5Z4+WoxSgXhRgLnc2A5uO8 WqwhRqXIiNlvkHRPydc2TT4Rv9eAht1Nx5C61qBajrCbZvoDXxl7YV25UN0XPz9dF2Rh nOJTz/jBa7PWJQmsuQowoAjVxMcAEClXt48= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3m0m19pqer-3 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 22 Nov 2022 11:53:36 -0800 Received: from twshared7043.05.ash9.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:82::e) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Tue, 22 Nov 2022 11:53:34 -0800 Received: by devbig309.ftw3.facebook.com (Postfix, from userid 128203) id D272412918BE2; Tue, 22 Nov 2022 11:53:24 -0800 (PST) From: Yonghong Song To: CC: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , , Martin KaFai Lau , KP Singh Subject: [PATCH bpf-next v8 1/4] compiler_types: Define __rcu as __attribute__((btf_type_tag("rcu"))) Date: Tue, 22 Nov 2022 11:53:24 -0800 Message-ID: <20221122195324.1780603-1-yhs@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20221122195319.1778570-1-yhs@fb.com> References: <20221122195319.1778570-1-yhs@fb.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-ORIG-GUID: ZQXa7vL5yyAtyYNxOOG48A0TxvFBfk-q X-Proofpoint-GUID: ZQXa7vL5yyAtyYNxOOG48A0TxvFBfk-q 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=2022-11-22_11,2022-11-18_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