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=-7.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 90138C433E0 for ; Thu, 16 Jul 2020 12:17:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 632C820739 for ; Thu, 16 Jul 2020 12:17:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=cloudflare.com header.i=@cloudflare.com header.b="yW3vYZAv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728123AbgGPMRj (ORCPT ); Thu, 16 Jul 2020 08:17:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55420 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728096AbgGPMRi (ORCPT ); Thu, 16 Jul 2020 08:17:38 -0400 Received: from mail-lj1-x243.google.com (mail-lj1-x243.google.com [IPv6:2a00:1450:4864:20::243]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 834B3C08C5C0 for ; Thu, 16 Jul 2020 05:17:38 -0700 (PDT) Received: by mail-lj1-x243.google.com with SMTP id f5so6853337ljj.10 for ; Thu, 16 Jul 2020 05:17:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=references:user-agent:from:to:cc:subject:in-reply-to:date :message-id:mime-version; bh=tscWjFcr/AdRUQgnIH2j5TMqV/ph1Tniwa7qjpNU7zU=; b=yW3vYZAvEURuyXC+7AoFhhYT8ibwcm5EmWW9YQW0IIzF9V9RCC06cY4p8l5oVCI3J6 rV54te2CZsxX0GcqSmtZi30tbp2g38+FaRrMrs9Us5bnOdNzQObPEnPFTNlYZnsaxV+b UVC8fWrzXZ5VSMSWy5+Ww6wdHdlHSmsS/3i1Q= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:references:user-agent:from:to:cc:subject :in-reply-to:date:message-id:mime-version; bh=tscWjFcr/AdRUQgnIH2j5TMqV/ph1Tniwa7qjpNU7zU=; b=EcDdULLQl1HG8HGe4/seGDx5EyXXkl558Xpw2DEPZJfUgCZkMAiCB9kVT/g85xc4tw eCQzg98ZBaluoqcw7KvKuSePAq4fDSZDwjVC1QSYA5EqXtXOMpMJXnkIGFqCkHzcakUg 01+c2Ul5LdF+7qGDhFk6P0EoZqrBHlgOqVVGHzM29uLNxykqRC5YfDQln4uvPsjJdffS dQ+NgBg3J5WM5zzfIDk8HPbJT/SxTOa3jC4ujDJZIFP92Ic6Jy8uAUCVrdE2fEyDkIgL t7FrzzveCw64O5dcXpYUxEJSPMsGjRhiLLp5Z2nX+sQwtJ8u/Ks4L3IuFMI9HSL3KUh9 qN8A== X-Gm-Message-State: AOAM5317usFant7tY1fhiRB//0XAUz1j9N/JbEwBLUSagBEmdlwY3Dz8 qyFF7WK7yQqaS/+xa+kvQqiJww== X-Google-Smtp-Source: ABdhPJxqWgGyQoj+nCEkyDTqOzwSP09fMuf9WwjDRBm3afE6PoJaTuGhPMHsGh3o0//OnnSg7UOhzw== X-Received: by 2002:a2e:780e:: with SMTP id t14mr2000146ljc.444.1594901856795; Thu, 16 Jul 2020 05:17:36 -0700 (PDT) Received: from cloudflare.com ([2a02:a310:c262:aa00:b35e:8938:2c2a:ba8b]) by smtp.gmail.com with ESMTPSA id y26sm1017207ljk.26.2020.07.16.05.17.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Jul 2020 05:17:36 -0700 (PDT) References: <20200713174654.642628-1-jakub@cloudflare.com> <20200713174654.642628-3-jakub@cloudflare.com> User-agent: mu4e 1.1.0; emacs 26.3 From: Jakub Sitnicki To: Andrii Nakryiko Cc: bpf , Networking , kernel-team , Alexei Starovoitov , Daniel Borkmann , "David S. Miller" , Jakub Kicinski , Marek Majkowski Subject: Re: [PATCH bpf-next v4 02/16] bpf: Introduce SK_LOOKUP program type with a dedicated attach point In-reply-to: Date: Thu, 16 Jul 2020 14:17:35 +0200 Message-ID: <877dv3y7q8.fsf@cloudflare.com> MIME-Version: 1.0 Content-Type: text/plain Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Thu, Jul 16, 2020 at 03:41 AM CEST, Andrii Nakryiko wrote: > On Mon, Jul 13, 2020 at 10:47 AM Jakub Sitnicki wrote: >> >> Add a new program type BPF_PROG_TYPE_SK_LOOKUP with a dedicated attach type >> BPF_SK_LOOKUP. The new program kind is to be invoked by the transport layer >> when looking up a listening socket for a new connection request for >> connection oriented protocols, or when looking up an unconnected socket for >> a packet for connection-less protocols. >> >> When called, SK_LOOKUP BPF program can select a socket that will receive >> the packet. This serves as a mechanism to overcome the limits of what >> bind() API allows to express. Two use-cases driving this work are: >> >> (1) steer packets destined to an IP range, on fixed port to a socket >> >> 192.0.2.0/24, port 80 -> NGINX socket >> >> (2) steer packets destined to an IP address, on any port to a socket >> >> 198.51.100.1, any port -> L7 proxy socket >> >> In its run-time context program receives information about the packet that >> triggered the socket lookup. Namely IP version, L4 protocol identifier, and >> address 4-tuple. Context can be further extended to include ingress >> interface identifier. >> >> To select a socket BPF program fetches it from a map holding socket >> references, like SOCKMAP or SOCKHASH, and calls bpf_sk_assign(ctx, sk, ...) >> helper to record the selection. Transport layer then uses the selected >> socket as a result of socket lookup. >> >> This patch only enables the user to attach an SK_LOOKUP program to a >> network namespace. Subsequent patches hook it up to run on local delivery >> path in ipv4 and ipv6 stacks. >> >> Suggested-by: Marek Majkowski >> Signed-off-by: Jakub Sitnicki >> --- >> >> Notes: >> v4: >> - Reintroduce narrow load support for most BPF context fields. (Yonghong) >> - Fix null-ptr-deref in BPF context access when IPv6 address not set. >> - Unpack v4/v6 IP address union in bpf_sk_lookup context type. >> - Add verifier support for ARG_PTR_TO_SOCKET_OR_NULL. >> - Allow resetting socket selection with bpf_sk_assign(ctx, NULL). >> - Document that bpf_sk_assign accepts a NULL socket. >> >> v3: >> - Allow bpf_sk_assign helper to replace previously selected socket only >> when BPF_SK_LOOKUP_F_REPLACE flag is set, as a precaution for multiple >> programs running in series to accidentally override each other's verdict. >> - Let BPF program decide that load-balancing within a reuseport socket group >> should be skipped for the socket selected with bpf_sk_assign() by passing >> BPF_SK_LOOKUP_F_NO_REUSEPORT flag. (Martin) >> - Extend struct bpf_sk_lookup program context with an 'sk' field containing >> the selected socket with an intention for multiple attached program >> running in series to see each other's choices. However, currently the >> verifier doesn't allow checking if pointer is set. >> - Use bpf-netns infra for link-based multi-program attachment. (Alexei) >> - Get rid of macros in convert_ctx_access to make it easier to read. >> - Disallow 1-,2-byte access to context fields containing IP addresses. >> >> v2: >> - Make bpf_sk_assign reject sockets that don't use RCU freeing. >> Update bpf_sk_assign docs accordingly. (Martin) >> - Change bpf_sk_assign proto to take PTR_TO_SOCKET as argument. (Martin) >> - Fix broken build when CONFIG_INET is not selected. (Martin) >> - Rename bpf_sk_lookup{} src_/dst_* fields remote_/local_*. (Martin) >> - Enforce BPF_SK_LOOKUP attach point on load & attach. (Martin) >> >> include/linux/bpf-netns.h | 3 + >> include/linux/bpf.h | 1 + >> include/linux/bpf_types.h | 2 + >> include/linux/filter.h | 17 ++++ >> include/uapi/linux/bpf.h | 77 ++++++++++++++++ >> kernel/bpf/net_namespace.c | 5 ++ >> kernel/bpf/syscall.c | 9 ++ >> kernel/bpf/verifier.c | 10 ++- >> net/core/filter.c | 179 +++++++++++++++++++++++++++++++++++++ >> scripts/bpf_helpers_doc.py | 9 +- >> 10 files changed, 308 insertions(+), 4 deletions(-) >> > > Looks good, two suggestions below. > > Acked-by: Andrii Nakryiko > > [...] > >> + >> +static const struct bpf_func_proto * >> +sk_lookup_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) >> +{ >> + switch (func_id) { >> + case BPF_FUNC_sk_assign: >> + return &bpf_sk_lookup_assign_proto; >> + case BPF_FUNC_sk_release: >> + return &bpf_sk_release_proto; >> + default: > > Wouldn't it be useful to have functions like > get_current_comm/get_current_pid_tgid/perf_event_output as well? > Similarly how they were added to a bunch of other socket-related BPF > program types recently? I can certainly see value in perf_event_output as a way to log/trace prog decisions. Less so for helpers that provide access to current task, as the prog usually will be called in softirq context. bpf_get_socket_cookie and bpf_get_netns_cookie have been on my mind, but first they need to be taught to accept ARG_PTR_TO_SOCKET. That is to say, I expected the list of allowed helpers to grow. > > >> + return bpf_base_func_proto(func_id); >> + } >> +} >> + > > [...] > >> + case offsetof(struct bpf_sk_lookup, local_ip4): >> + *insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->src_reg, >> + bpf_target_off(struct bpf_sk_lookup_kern, >> + v4.daddr, 4, target_size)); >> + break; >> + >> + case bpf_ctx_range_till(struct bpf_sk_lookup, >> + remote_ip6[0], remote_ip6[3]): >> +#if IS_ENABLED(CONFIG_IPV6) > > nit: if you added {} to this case block, you could have combined the > above `int off` section with this one. Nifty. Thanks. > >> + off = si->off; >> + off -= offsetof(struct bpf_sk_lookup, remote_ip6[0]); >> + off += bpf_target_off(struct in6_addr, s6_addr32[0], 4, target_size); >> + *insn++ = BPF_LDX_MEM(BPF_SIZEOF(void *), si->dst_reg, si->src_reg, >> + offsetof(struct bpf_sk_lookup_kern, v6.saddr)); >> + *insn++ = BPF_JMP_IMM(BPF_JEQ, si->dst_reg, 0, 1); >> + *insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg, off); >> +#else >> + *insn++ = BPF_MOV32_IMM(si->dst_reg, 0); >> +#endif >> + break; >> + > > [...]