From patchwork Mon Mar 12 19:23:34 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Fastabend X-Patchwork-Id: 884799 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=gmail.com Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 400SZq5sMGz9sBq for ; Tue, 13 Mar 2018 06:23:47 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932282AbeCLTXj (ORCPT ); Mon, 12 Mar 2018 15:23:39 -0400 Received: from [75.106.27.153] ([75.106.27.153]:59506 "EHLO john-Precision-Tower-5810" rhost-flags-FAIL-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S932102AbeCLTXi (ORCPT ); Mon, 12 Mar 2018 15:23:38 -0400 Received: from [127.0.1.1] (localhost [127.0.0.1]) by john-Precision-Tower-5810 (Postfix) with ESMTP id CF414D442E0; Mon, 12 Mar 2018 12:23:34 -0700 (PDT) Subject: [bpf-next PATCH v2 06/18] bpf: sockmap, add bpf_msg_apply_bytes() helper From: John Fastabend To: davem@davemloft.net, ast@kernel.org, daniel@iogearbox.net, davejwatson@fb.com Cc: netdev@vger.kernel.org Date: Mon, 12 Mar 2018 12:23:34 -0700 Message-ID: <20180312192334.8039.98220.stgit@john-Precision-Tower-5810> In-Reply-To: <20180312192034.8039.70022.stgit@john-Precision-Tower-5810> References: <20180312192034.8039.70022.stgit@john-Precision-Tower-5810> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org A single sendmsg or sendfile system call can contain multiple logical messages that a BPF program may want to read and apply a verdict. But, without an apply_bytes helper any verdict on the data applies to all bytes in the sendmsg/sendfile. Alternatively, a BPF program may only care to read the first N bytes of a msg. If the payload is large say MB or even GB setting up and calling the BPF program repeatedly for all bytes, even though the verdict is already known, creates unnecessary overhead. To allow BPF programs to control how many bytes a given verdict applies to we implement a bpf_msg_apply_bytes() helper. When called from within a BPF program this sets a counter, internal to the BPF infrastructure, that applies the last verdict to the next N bytes. If the N is smaller than the current data being processed from a sendmsg/sendfile call, the first N bytes will be sent and the BPF program will be re-run with start_data pointing to the N+1 byte. If N is larger than the current data being processed the BPF verdict will be applied to multiple sendmsg/sendfile calls until N bytes are consumed. Note1 if a socket closes with apply_bytes counter non-zero this is not a problem because data is not being buffered for N bytes and is sent as its received. Note2 if this is operating in the sendpage context the data pointers may be zeroed after this call if the apply walks beyond a msg_pull_data() call specified data range. (helper implemented shortly in this series). Signed-off-by: John Fastabend Acked-by: David S. Miller --- include/uapi/linux/bpf.h | 3 ++- net/core/filter.c | 16 ++++++++++++++++ 2 files changed, 18 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index b8275f0..e50c61f 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -769,7 +769,8 @@ enum bpf_attach_type { FN(getsockopt), \ FN(override_return), \ FN(sock_ops_cb_flags_set), \ - FN(msg_redirect_map), + FN(msg_redirect_map), \ + FN(msg_apply_bytes), /* integer value in 'imm' field of BPF_CALL instruction selects which helper * function eBPF program intends to call diff --git a/net/core/filter.c b/net/core/filter.c index 314c311..df2a8f4 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -1928,6 +1928,20 @@ struct sock *do_msg_redirect_map(struct sk_msg_buff *msg) .arg4_type = ARG_ANYTHING, }; +BPF_CALL_2(bpf_msg_apply_bytes, struct sk_msg_buff *, msg, u64, bytes) +{ + msg->apply_bytes = bytes; + return 0; +} + +static const struct bpf_func_proto bpf_msg_apply_bytes_proto = { + .func = bpf_msg_apply_bytes, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_CTX, + .arg2_type = ARG_ANYTHING, +}; + BPF_CALL_1(bpf_get_cgroup_classid, const struct sk_buff *, skb) { return task_get_classid(skb); @@ -3634,6 +3648,8 @@ static const struct bpf_func_proto *sk_msg_func_proto(enum bpf_func_id func_id) switch (func_id) { case BPF_FUNC_msg_redirect_map: return &bpf_msg_redirect_map_proto; + case BPF_FUNC_msg_apply_bytes: + return &bpf_msg_apply_bytes_proto; default: return bpf_base_func_proto(func_id); }