From patchwork Wed Sep 27 22:57:57 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrii Nakryiko X-Patchwork-Id: 13401747 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 6CE1BE80ABC for ; Wed, 27 Sep 2023 22:58:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229460AbjI0W6s convert rfc822-to-8bit (ORCPT ); Wed, 27 Sep 2023 18:58:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52010 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229648AbjI0W6q (ORCPT ); Wed, 27 Sep 2023 18:58:46 -0400 Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89D64114 for ; Wed, 27 Sep 2023 15:58:44 -0700 (PDT) Received: from pps.filterd (m0148460.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 38RLU0Sv032000 for ; Wed, 27 Sep 2023 15:58:43 -0700 Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3tcvbsrpry-3 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Wed, 27 Sep 2023 15:58:43 -0700 Received: from twshared27355.37.frc1.facebook.com (2620:10d:c0a8:1b::30) by mail.thefacebook.com (2620:10d:c0a8:83::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Wed, 27 Sep 2023 15:58:42 -0700 Received: by devbig019.vll3.facebook.com (Postfix, from userid 137359) id D18BB38C9A621; Wed, 27 Sep 2023 15:58:32 -0700 (PDT) From: Andrii Nakryiko To: , CC: , , , , , , Subject: [PATCH v6 bpf-next 01/13] bpf: align CAP_NET_ADMIN checks with bpf_capable() approach Date: Wed, 27 Sep 2023 15:57:57 -0700 Message-ID: <20230927225809.2049655-2-andrii@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230927225809.2049655-1-andrii@kernel.org> References: <20230927225809.2049655-1-andrii@kernel.org> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: FpZ8T2QTRveUynjqtgTydWw1dsqZJdfx X-Proofpoint-ORIG-GUID: FpZ8T2QTRveUynjqtgTydWw1dsqZJdfx X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.267,Aquarius:18.0.980,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-09-27_15,2023-09-27_01,2023-05-22_02 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Within BPF syscall handling code CAP_NET_ADMIN checks stand out a bit compared to CAP_BPF and CAP_PERFMON checks. For the latter, CAP_BPF or CAP_PERFMON are checked first, but if they are not set, CAP_SYS_ADMIN takes over and grants whatever part of BPF syscall is required. Similar kind of checks that involve CAP_NET_ADMIN are not so consistent. One out of four uses does follow CAP_BPF/CAP_PERFMON model: during BPF_PROG_LOAD, if the type of BPF program is "network-related" either CAP_NET_ADMIN or CAP_SYS_ADMIN is required to proceed. But in three other cases CAP_NET_ADMIN is required even if CAP_SYS_ADMIN is set: - when creating DEVMAP/XDKMAP/CPU_MAP maps; - when attaching CGROUP_SKB programs; - when handling BPF_PROG_QUERY command. This patch is changing the latter three cases to follow BPF_PROG_LOAD model, that is allowing to proceed under either CAP_NET_ADMIN or CAP_SYS_ADMIN. This also makes it cleaner in subsequent BPF token patches to switch wholesomely to a generic bpf_token_capable(int cap) check, that always falls back to CAP_SYS_ADMIN if requested capability is missing. Cc: Jakub Kicinski Signed-off-by: Andrii Nakryiko --- kernel/bpf/syscall.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 6b5280f14a53..7445dad01fb3 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1097,6 +1097,11 @@ static int map_check_btf(struct bpf_map *map, const struct btf *btf, return ret; } +static bool bpf_net_capable(void) +{ + return capable(CAP_NET_ADMIN) || capable(CAP_SYS_ADMIN); +} + #define BPF_MAP_CREATE_LAST_FIELD map_extra /* called via syscall */ static int map_create(union bpf_attr *attr) @@ -1200,7 +1205,7 @@ static int map_create(union bpf_attr *attr) case BPF_MAP_TYPE_DEVMAP: case BPF_MAP_TYPE_DEVMAP_HASH: case BPF_MAP_TYPE_XSKMAP: - if (!capable(CAP_NET_ADMIN)) + if (!bpf_net_capable()) return -EPERM; break; default: @@ -2595,7 +2600,7 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) !bpf_capable()) return -EPERM; - if (is_net_admin_prog_type(type) && !capable(CAP_NET_ADMIN) && !capable(CAP_SYS_ADMIN)) + if (is_net_admin_prog_type(type) && !bpf_net_capable()) return -EPERM; if (is_perfmon_prog_type(type) && !perfmon_capable()) return -EPERM; @@ -3740,7 +3745,7 @@ static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog, case BPF_PROG_TYPE_SK_LOOKUP: return attach_type == prog->expected_attach_type ? 0 : -EINVAL; case BPF_PROG_TYPE_CGROUP_SKB: - if (!capable(CAP_NET_ADMIN)) + if (!bpf_net_capable()) /* cg-skb progs can be loaded by unpriv user. * check permissions at attach time. */ @@ -3924,7 +3929,7 @@ static int bpf_prog_detach(const union bpf_attr *attr) static int bpf_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr) { - if (!capable(CAP_NET_ADMIN)) + if (!bpf_net_capable()) return -EPERM; if (CHECK_ATTR(BPF_PROG_QUERY)) return -EINVAL;