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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 4C71BC433B4 for ; Wed, 21 Apr 2021 23:41:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2639D613FA for ; Wed, 21 Apr 2021 23:41:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234986AbhDUXmI (ORCPT ); Wed, 21 Apr 2021 19:42:08 -0400 Received: from www62.your-server.de ([213.133.104.62]:50060 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232353AbhDUXmI (ORCPT ); Wed, 21 Apr 2021 19:42:08 -0400 Received: from sslproxy02.your-server.de ([78.47.166.47]) by www62.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92.3) (envelope-from ) id 1lZMTM-000GyF-U2; Thu, 22 Apr 2021 01:41:32 +0200 Received: from [85.7.101.30] (helo=linux.home) by sslproxy02.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lZMTM-000FjC-Ka; Thu, 22 Apr 2021 01:41:32 +0200 Subject: Re: [PATCH bpf-next v3 2/3] libbpf: add low level TC-BPF API To: Kumar Kartikeya Dwivedi Cc: bpf@vger.kernel.org, =?UTF-8?Q?Toke_H=c3=b8iland-J=c3=b8rgensen?= , Alexei Starovoitov , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , "David S. Miller" , Jakub Kicinski , Shaun Crampton , Jesper Dangaard Brouer , netdev@vger.kernel.org References: <20210420193740.124285-1-memxor@gmail.com> <20210420193740.124285-3-memxor@gmail.com> <9b0aab2c-9b92-0bcb-2064-f66dd39e7552@iogearbox.net> <20210421230858.ruwqw5jvsy7cjioy@apollo> <21c55619-e26d-d901-076e-20f55302c2fd@iogearbox.net> <20210421233054.sgs5lemcuycx4vjb@apollo> From: Daniel Borkmann Message-ID: Date: Thu, 22 Apr 2021 01:41:32 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20210421233054.sgs5lemcuycx4vjb@apollo> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.102.4/26147/Wed Apr 21 13:06:05 2021) Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 4/22/21 1:30 AM, Kumar Kartikeya Dwivedi wrote: > On Thu, Apr 22, 2021 at 04:51:55AM IST, Daniel Borkmann wrote: >> On 4/22/21 1:08 AM, Kumar Kartikeya Dwivedi wrote: >>> On Thu, Apr 22, 2021 at 04:29:28AM IST, Daniel Borkmann wrote: >>>> On 4/20/21 9:37 PM, Kumar Kartikeya Dwivedi wrote: >>>> [...] >>>>> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h >>>>> index bec4e6a6e31d..b4ed6a41ea70 100644 >>>>> --- a/tools/lib/bpf/libbpf.h >>>>> +++ b/tools/lib/bpf/libbpf.h >>>>> @@ -16,6 +16,8 @@ >>>>> #include >>>>> #include // for size_t >>>>> #include >>>>> +#include >>>>> +#include >>>>> #include "libbpf_common.h" >>>>> @@ -775,6 +777,48 @@ LIBBPF_API int bpf_linker__add_file(struct bpf_linker *linker, const char *filen >>>>> LIBBPF_API int bpf_linker__finalize(struct bpf_linker *linker); >>>>> LIBBPF_API void bpf_linker__free(struct bpf_linker *linker); >>>>> +/* Convenience macros for the clsact attach hooks */ >>>>> +#define BPF_TC_CLSACT_INGRESS TC_H_MAKE(TC_H_CLSACT, TC_H_MIN_INGRESS) >>>>> +#define BPF_TC_CLSACT_EGRESS TC_H_MAKE(TC_H_CLSACT, TC_H_MIN_EGRESS) >>>> >>>> I would abstract those away into an enum, plus avoid having to pull in >>>> linux/pkt_sched.h and linux/tc_act/tc_bpf.h from main libbpf.h header. >>>> >>>> Just add a enum { BPF_TC_DIR_INGRESS, BPF_TC_DIR_EGRESS, } and then the >>>> concrete tc bits (TC_H_MAKE()) can be translated internally. >>> >>> Ok, will do. >>> >>>>> +struct bpf_tc_opts { >>>>> + size_t sz; >>>> >>>> Is this set anywhere? >>> >>> This is needed by the OPTS_* infrastructure. >>> >>>>> + __u32 handle; >>>>> + __u32 class_id; >>>> >>>> I'd remove class_id from here as well given in direct-action a BPF prog can >>>> set it if needed. >>> >>> Ok, makes sense. >>> >>>>> + __u16 priority; >>>>> + bool replace; >>>>> + size_t :0; >>>> >>>> What's the rationale for this padding? >>> >>> dde7b3f5f2f4 ("libbpf: Add explicit padding to bpf_xdp_set_link_opts") >> >> Hm, fair enough. >> >>>>> +}; >>>>> + >>>>> +#define bpf_tc_opts__last_field replace >>>>> + >>>>> +/* Acts as a handle for an attached filter */ >>>>> +struct bpf_tc_attach_id { >>>> >>>> nit: maybe bpf_tc_ctx >>> >>> Noted. >>> >>>>> + __u32 handle; >>>>> + __u16 priority; >>>>> +}; >>>>> + >>>>> +struct bpf_tc_info { >>>>> + struct bpf_tc_attach_id id; >>>>> + __u16 protocol; >>>>> + __u32 chain_index; >>>>> + __u32 prog_id; >>>>> + __u8 tag[BPF_TAG_SIZE]; >>>>> + __u32 class_id; >>>>> + __u32 bpf_flags; >>>>> + __u32 bpf_flags_gen; >>>> >>>> Given we do not yet have any setters e.g. for offload, etc, the one thing >>>> I'd see useful and crucial initially is prog_id. >>>> >>>> The protocol, chain_index, and I would also include tag should be dropped. >>> >>> A future user of this API needs to know the tag, so I would like to keep that. >>> The rest we can drop, and probably document the default values explicitly. >> >> Couldn't this be added along with the future patch for the [future] user? > > True. > >> The tag should be the tag of the prog itself, so if you have prog_id, you >> could also retrieve the same tag from the prog. The tag was basically from >> the early days where we didn't have bpf_prog_get_info_by_fd(). >> >> What does that future user need to do different here? > > From Shaun Crampton: > "My particular use case is to load a program, link it with its maps and then > check if its tag matches the existing program on the interface (and if so, abort > the update)" > > Also CC'd, they would be able to elaborate better, and whether or not dropping > it is ok. Nope, just get it from the prog itself.