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=-9.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 127E1C2D0DC for ; Tue, 31 Dec 2019 06:20:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CA4D6206DB for ; Tue, 31 Dec 2019 06:20:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="OUNDirK/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726307AbfLaGUt (ORCPT ); Tue, 31 Dec 2019 01:20:49 -0500 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:35370 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726293AbfLaGUt (ORCPT ); Tue, 31 Dec 2019 01:20:49 -0500 Received: from pps.filterd (m0109331.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id xBV6FOL4007386 for ; Mon, 30 Dec 2019 22:20:47 -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-type; s=facebook; bh=30EPOy1ffVJYg6REh3jtH/nWup0JAgJw0cyP0UKgyM0=; b=OUNDirK/Fc5JbHa1UQA83jVdzSfWxn9oNy3GiMg/BhBN0kotYncMRnky9zAd3Th0Cpmm /ILjpmNWgBIh9USDcqSUwc6QIpYOpq2jJbOwqQLLO+BlI9z8QOM7lkV8L0Vv0zOhHNRD TRn1EYYW04nsS0A8pUnWMGSM20xcblbXH+A= Received: from mail.thefacebook.com (mailout.thefacebook.com [199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 2x65rq9ft7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT) for ; Mon, 30 Dec 2019 22:20:47 -0800 Received: from intmgw001.06.prn3.facebook.com (2620:10d:c081:10::13) by mail.thefacebook.com (2620:10d:c081:35::130) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA) id 15.1.1713.5; Mon, 30 Dec 2019 22:20:46 -0800 Received: by devbig005.ftw2.facebook.com (Postfix, from userid 6611) id 4A549294410B; Mon, 30 Dec 2019 22:20:46 -0800 (PST) Smtp-Origin-Hostprefix: devbig From: Martin KaFai Lau Smtp-Origin-Hostname: devbig005.ftw2.facebook.com To: CC: Alexei Starovoitov , Daniel Borkmann , David Miller , , Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH bpf-next v3 04/11] bpf: Support bitfield read access in btf_struct_access Date: Mon, 30 Dec 2019 22:20:46 -0800 Message-ID: <20191231062046.281300-1-kafai@fb.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20191231062037.280596-1-kafai@fb.com> References: <20191231062037.280596-1-kafai@fb.com> X-FB-Internal: Safe MIME-Version: 1.0 Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,18.0.572 definitions=2019-12-30_08:2019-12-27,2019-12-30 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 adultscore=0 mlxlogscore=825 mlxscore=0 lowpriorityscore=0 bulkscore=0 suspectscore=13 spamscore=0 clxscore=1015 phishscore=0 malwarescore=0 priorityscore=1501 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-1912310050 X-FB-Internal: deliver Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org This patch allows bitfield access as a scalar. It checks "off + size > t->size" to avoid accessing bitfield end up accessing beyond the struct. This check is done outside of the loop since it is applicable to all access. It also takes this chance to break early on the "off < moff" case. Signed-off-by: Martin KaFai Lau --- kernel/bpf/btf.c | 44 +++++++++++++++++++++++++++++++++++++++----- 1 file changed, 39 insertions(+), 5 deletions(-) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 6a5ccb748a72..48bbde2e1c1e 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -3744,19 +3744,53 @@ int btf_struct_access(struct bpf_verifier_log *log, return -EINVAL; } - for_each_member(i, t, member) { - if (btf_member_bitfield_size(t, member)) - /* bitfields are not supported yet */ - continue; + if (off + size > t->size) { + bpf_log(log, "access beyond struct %s at off %u size %u\n", + tname, off, size); + return -EACCES; + } + for_each_member(i, t, member) { /* offset of the field in bytes */ moff = btf_member_bit_offset(t, member) / 8; if (off + size <= moff) /* won't find anything, field is already too far */ break; + + if (btf_member_bitfield_size(t, member)) { + u32 end_bit = btf_member_bit_offset(t, member) + + btf_member_bitfield_size(t, member); + + /* off <= moff instead of off == moff because clang + * does not generate a BTF member for anonymous + * bitfield like the ":16" here: + * struct { + * int :16; + * int x:8; + * }; + */ + if (off <= moff && + BITS_ROUNDUP_BYTES(end_bit) <= off + size) + return SCALAR_VALUE; + + /* off may be accessing a following member + * + * or + * + * Doing partial access at either end of this + * bitfield. Continue on this case also to + * treat it as not accessing this bitfield + * and eventually error out as field not + * found to keep it simple. + * It could be relaxed if there was a legit + * partial access case later. + */ + continue; + } + /* In case of "off" is pointing to holes of a struct */ if (off < moff) - continue; + break; /* type of the field */ mtype = btf_type_by_id(btf_vmlinux, member->type); -- 2.17.1