From patchwork Fri Aug 21 00:28:03 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Udip Pant X-Patchwork-Id: 1348737 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=bpf-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=reject dis=none) header.from=fb.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=fb.com header.i=@fb.com header.a=rsa-sha256 header.s=facebook header.b=hOOAhYdU; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BXj6V29Q3z9sR4 for ; Fri, 21 Aug 2020 10:28:18 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725885AbgHUA2R (ORCPT ); Thu, 20 Aug 2020 20:28:17 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:48216 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725834AbgHUA2Q (ORCPT ); Thu, 20 Aug 2020 20:28:16 -0400 Received: from pps.filterd (m0089730.ppops.net [127.0.0.1]) by m0089730.ppops.net (8.16.0.42/8.16.0.42) with SMTP id 07L0OptQ005682 for ; Thu, 20 Aug 2020 17:28:15 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding : content-type; s=facebook; bh=/uUFrz2pplyNeuzwjVTtdWHekCwyi/O0CKqPnUBAh2Y=; b=hOOAhYdUEg3OBsjRRyxwaFCjD/1f33nWqNGHwOPPwGn1LM6auWEGD2Q5necwVsEYsPO4 q498YGj0CaRMsctVXPRxRJj0h7vfVR8I+1QavTnNHFq973PtO7eeTykkAizUNG+kLgo2 TaOyb0keev+lbBQlY3GlyP1m6RZ0EdUzEw8= Received: from maileast.thefacebook.com ([163.114.130.16]) by m0089730.ppops.net with ESMTP id 331hcbwgmy-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Thu, 20 Aug 2020 17:28:15 -0700 Received: from intmgw004.08.frc2.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Thu, 20 Aug 2020 17:28:14 -0700 Received: by devbig218.frc2.facebook.com (Postfix, from userid 116055) id 14363207539; Thu, 20 Aug 2020 17:28:14 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Udip Pant Smtp-Origin-Hostname: devbig218.frc2.facebook.com To: Udip Pant , Alexei Starovoitov , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , "David S . Miller" CC: , , Smtp-Origin-Cluster: frc2c02 Subject: [PATCH v2 bpf 1/2] bpf: verifier: check for packet data access based on target prog Date: Thu, 20 Aug 2020 17:28:03 -0700 Message-ID: <20200821002804.546826-1-udippant@fb.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235, 18.0.687 definitions=2020-08-20_07:2020-08-19,2020-08-20 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 spamscore=0 priorityscore=1501 suspectscore=0 clxscore=1015 bulkscore=0 mlxlogscore=940 lowpriorityscore=0 phishscore=0 impostorscore=0 adultscore=0 mlxscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008210002 X-FB-Internal: deliver Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org While using dynamic program extension (of type BPF_PROG_TYPE_EXT), we need to check the program type of the target program to grant the read / write access to the packet data. The BPF_PROG_TYPE_EXT type can be used to extend types such as XDP, SKB and others. Since the BPF_PROG_TYPE_EXT program type on itself is just a placeholder for those, we need this extended check for those target programs to actually work while using this option. Tested this with a freplace xdp program. Without this patch, the verifier fails with error 'cannot write into packet'. Signed-off-by: Udip Pant --- kernel/bpf/verifier.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index ef938f17b944..4d7604430994 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2629,7 +2629,11 @@ static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, const struct bpf_call_arg_meta *meta, enum bpf_access_type t) { - switch (env->prog->type) { + struct bpf_prog *prog = env->prog; + enum bpf_prog_type prog_type = prog->aux->linked_prog ? + prog->aux->linked_prog->type : prog->type; + + switch (prog_type) { /* Program types only with direct read access go here! */ case BPF_PROG_TYPE_LWT_IN: case BPF_PROG_TYPE_LWT_OUT: