From patchwork Tue Jun 9 13:31:46 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jesper Dangaard Brouer X-Patchwork-Id: 217904 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=-6.9 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 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 4780CC433E0 for ; Tue, 9 Jun 2020 13:32:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 243E12074B for ; Tue, 9 Jun 2020 13:32:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="aPBSmaXq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730109AbgFINcG (ORCPT ); Tue, 9 Jun 2020 09:32:06 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:36322 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729000AbgFINcE (ORCPT ); Tue, 9 Jun 2020 09:32:04 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1591709522; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=PFvWo3CucggmGPriTROKDBuxeyYpTwvcGiM7IDwsL8o=; b=aPBSmaXqdndgA5Ik0oi8iiqivgLLNzUt++rQpIyi4GfrsF1GmI2hCPfTHEMngbwQJnUgTu D4xAKmVJDQn5VJRniAf88+OaZhOEJ8wAaUzmoUEED3e+CqaNAxCx74mND8QS3YpKCsQ/Gn Qnx5CZNDK4In4KJc42xJAj8hDOHtcZU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-489-JamM1E_IMkWXJ1x5qGXcBA-1; Tue, 09 Jun 2020 09:31:52 -0400 X-MC-Unique: JamM1E_IMkWXJ1x5qGXcBA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id F235A81CBE1; Tue, 9 Jun 2020 13:31:50 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.40.208.32]) by smtp.corp.redhat.com (Postfix) with ESMTP id BD5D910190A7; Tue, 9 Jun 2020 13:31:47 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id E68F8300003EB; Tue, 9 Jun 2020 15:31:46 +0200 (CEST) Subject: [PATCH bpf V2 1/2] bpf: devmap adjust uapi for attach bpf program From: Jesper Dangaard Brouer To: David Ahern , bpf@vger.kernel.org, Alexei Starovoitov Cc: Jesper Dangaard Brouer , netdev@vger.kernel.org, Daniel Borkmann , Andrii Nakryiko , Lorenzo Bianconi Date: Tue, 09 Jun 2020 15:31:46 +0200 Message-ID: <159170950687.2102545.7235914718298050113.stgit@firesoul> In-Reply-To: <159170947966.2102545.14401752480810420709.stgit@firesoul> References: <159170947966.2102545.14401752480810420709.stgit@firesoul> User-Agent: StGit/0.19 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org V2: - Defer changing BPF-syscall to start at file-descriptor 1 - Use {} to zero initialise struct. The recent commit fbee97feed9b ("bpf: Add support to attach bpf program to a devmap entry"), introduced ability to attach (and run) a separate XDP bpf_prog for each devmap entry. A bpf_prog is added via a file-descriptor. As zero were a valid FD, not using the feature requires using value minus-1. The UAPI is extended via tail-extending struct bpf_devmap_val and using map->value_size to determine the feature set. This will break older userspace applications not using the bpf_prog feature. Consider an old userspace app that is compiled against newer kernel uapi/bpf.h, it will not know that it need to initialise the member bpf_prog.fd to minus-1. Thus, users will be forced to update source code to get program running on newer kernels. This patch remove the minus-1 checks, and have zero mean feature isn't used. Followup patches either for kernel or libbpf should handle and avoid returning file-descriptor zero in the first place. Fixes: fbee97feed9b ("bpf: Add support to attach bpf program to a devmap entry") Signed-off-by: Jesper Dangaard Brouer --- include/uapi/linux/bpf.h | 13 +++++++++++++ kernel/bpf/devmap.c | 17 ++++------------- 2 files changed, 17 insertions(+), 13 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index c65b374a5090..19684813faae 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3761,6 +3761,19 @@ struct xdp_md { __u32 egress_ifindex; /* txq->dev->ifindex */ }; +/* DEVMAP map-value layout + * + * The struct data-layout of map-value is a configuration interface. + * New members can only be added to the end of this structure. + */ +struct bpf_devmap_val { + __u32 ifindex; /* device index */ + union { + int fd; /* prog fd on map write */ + __u32 id; /* prog id on map read */ + } bpf_prog; +}; + enum sk_action { SK_DROP = 0, SK_PASS, diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index 854b09beb16b..899a30a67cc1 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -60,15 +60,6 @@ struct xdp_dev_bulk_queue { unsigned int count; }; -/* DEVMAP values */ -struct bpf_devmap_val { - u32 ifindex; /* device index */ - union { - int fd; /* prog fd on map write */ - u32 id; /* prog id on map read */ - } bpf_prog; -}; - struct bpf_dtab_netdev { struct net_device *dev; /* must be first member, due to tracepoint */ struct hlist_node index_hlist; @@ -618,7 +609,7 @@ static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net, if (!dev->dev) goto err_out; - if (val->bpf_prog.fd >= 0) { + if (val->bpf_prog.fd > 0) { prog = bpf_prog_get_type_dev(val->bpf_prog.fd, BPF_PROG_TYPE_XDP, false); if (IS_ERR(prog)) @@ -652,8 +643,8 @@ static int __dev_map_update_elem(struct net *net, struct bpf_map *map, void *key, void *value, u64 map_flags) { struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map); - struct bpf_devmap_val val = { .bpf_prog.fd = -1 }; struct bpf_dtab_netdev *dev, *old_dev; + struct bpf_devmap_val val = {}; u32 i = *(u32 *)key; if (unlikely(map_flags > BPF_EXIST)) @@ -669,7 +660,7 @@ static int __dev_map_update_elem(struct net *net, struct bpf_map *map, if (!val.ifindex) { dev = NULL; /* can not specify fd if ifindex is 0 */ - if (val.bpf_prog.fd != -1) + if (val.bpf_prog.fd > 0) return -EINVAL; } else { dev = __dev_map_alloc_node(net, dtab, &val, i); @@ -699,8 +690,8 @@ static int __dev_map_hash_update_elem(struct net *net, struct bpf_map *map, void *key, void *value, u64 map_flags) { struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map); - struct bpf_devmap_val val = { .bpf_prog.fd = -1 }; struct bpf_dtab_netdev *dev, *old_dev; + struct bpf_devmap_val val = {}; u32 idx = *(u32 *)key; unsigned long flags; int err = -EEXIST;