From patchwork Mon May 4 06:26:04 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yonghong Song X-Patchwork-Id: 220003 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 8467FC47257 for ; Mon, 4 May 2020 06:26:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6432B206EB for ; Mon, 4 May 2020 06:26:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="VcjlKg+Y" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727845AbgEDG00 (ORCPT ); Mon, 4 May 2020 02:26:26 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:3656 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727983AbgEDG0R (ORCPT ); Mon, 4 May 2020 02:26:17 -0400 Received: from pps.filterd (m0001303.ppops.net [127.0.0.1]) by m0001303.ppops.net (8.16.0.42/8.16.0.42) with SMTP id 0446E1KR004041 for ; Sun, 3 May 2020 23:26:16 -0700 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=s0BuE6KozQMvUZnf6ROrCnL95bGCMpeivkGQCihDo7g=; b=VcjlKg+Y0ZxgslFDWUhXT9GyHNHTmPXnA/BXum4GiKiiTrigMIrUMHs/8hrD2qV7WyRM AjQxgEyX7IrTn6tyN5VV2BinrHhv967Mk76Y/YSN5IecNK5UvySgkskW83G0ndTJi2co 2MHvXQo22E6vcYnfYxf5KftbfJeajQMNsz8= Received: from maileast.thefacebook.com ([163.114.130.16]) by m0001303.ppops.net with ESMTP id 30s4hp71m1-9 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Sun, 03 May 2020 23:26:16 -0700 Received: from intmgw002.08.frc2.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::4) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1847.3; Sun, 3 May 2020 23:26:12 -0700 Received: by devbig003.ftw2.facebook.com (Postfix, from userid 128203) id A570B3702037; Sun, 3 May 2020 23:26:04 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Yonghong Song Smtp-Origin-Hostname: devbig003.ftw2.facebook.com To: Andrii Nakryiko , , Martin KaFai Lau , CC: Alexei Starovoitov , Daniel Borkmann , Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH bpf-next v2 15/20] bpf: support variable length array in tracing programs Date: Sun, 3 May 2020 23:26:04 -0700 Message-ID: <20200504062604.2048804-1-yhs@fb.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200504062547.2047304-1-yhs@fb.com> References: <20200504062547.2047304-1-yhs@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.676 definitions=2020-05-04_02:2020-05-01,2020-05-04 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 adultscore=0 suspectscore=0 malwarescore=0 impostorscore=0 phishscore=0 lowpriorityscore=0 mlxscore=0 mlxlogscore=715 bulkscore=0 clxscore=1015 spamscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2005040054 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org In /proc/net/ipv6_route, we have struct fib6_info { struct fib6_table *fib6_table; ... struct fib6_nh fib6_nh[0]; } struct fib6_nh { struct fib_nh_common nh_common; struct rt6_info **rt6i_pcpu; struct rt6_exception_bucket *rt6i_exception_bucket; }; struct fib_nh_common { ... u8 nhc_gw_family; ... } The access: struct fib6_nh *fib6_nh = &rt->fib6_nh; ... fib6_nh->nh_common.nhc_gw_family ... This patch ensures such an access is handled properly. Signed-off-by: Yonghong Song --- kernel/bpf/btf.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index c490fbde22d4..dcd233139294 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -3833,6 +3833,7 @@ int btf_struct_access(struct bpf_verifier_log *log, const struct btf_type *mtype, *elem_type = NULL; const struct btf_member *member; const char *tname, *mname; + u32 vlen; again: tname = __btf_name_by_offset(btf_vmlinux, t->name_off); @@ -3841,7 +3842,43 @@ int btf_struct_access(struct bpf_verifier_log *log, return -EINVAL; } + vlen = btf_type_vlen(t); if (off + size > t->size) { + /* If the last element is a variable size array, we may + * need to relax the rule. + */ + struct btf_array *array_elem; + + if (vlen == 0) + goto error; + + member = btf_type_member(t) + vlen - 1; + mtype = btf_type_skip_modifiers(btf_vmlinux, member->type, + NULL); + if (!btf_type_is_array(mtype)) + goto error; + + array_elem = (struct btf_array *)(mtype + 1); + if (array_elem->nelems != 0) + goto error; + + moff = btf_member_bit_offset(t, member) / 8; + if (off < moff) + goto error; + + /* Only allow structure for now, can be relaxed for + * other types later. + */ + elem_type = btf_type_skip_modifiers(btf_vmlinux, + array_elem->type, NULL); + if (!btf_type_is_struct(elem_type)) + goto error; + + off = (off - moff) % elem_type->size; + return btf_struct_access(log, elem_type, off, size, atype, + next_btf_id); + +error: bpf_log(log, "access beyond struct %s at off %u size %u\n", tname, off, size); return -EACCES;