From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lawrence Brakmo Subject: [PATCH net-next v4 06/16] bpf: Sample bpf program to set initial window Date: Wed, 28 Jun 2017 10:31:14 -0700 Message-ID: <20170628173124.3299500-7-brakmo@fb.com> References: <20170628173124.3299500-1-brakmo@fb.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Kernel Team , Blake Matheny , Alexei Starovoitov , Daniel Borkmann , David Ahern To: netdev Return-path: Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:51071 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751532AbdF1Rbc (ORCPT ); Wed, 28 Jun 2017 13:31:32 -0400 Received: from pps.filterd (m0044012.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v5SHURAb023861 for ; Wed, 28 Jun 2017 10:31:32 -0700 Received: from mail.thefacebook.com ([199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 2bc8vphukh-1 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Wed, 28 Jun 2017 10:31:32 -0700 Received: from facebook.com (2401:db00:11:d025:face:0:13:0) by mx-out.facebook.com (10.212.232.59) with ESMTP id 9f7520b85c2711e79c7e0002c991e86a-2133a8f0 for ; Wed, 28 Jun 2017 10:31:30 -0700 In-Reply-To: <20170628173124.3299500-1-brakmo@fb.com> Sender: netdev-owner@vger.kernel.org List-ID: The sample bpf program, tcp_rwnd_kern.c, sets the initial advertized window to 40 packets in an environment where distinct IPv6 prefixes indicate that both hosts are not in the same data center. Signed-off-by: Lawrence Brakmo --- samples/bpf/Makefile | 1 + samples/bpf/tcp_rwnd_kern.c | 61 +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 62 insertions(+) create mode 100644 samples/bpf/tcp_rwnd_kern.c diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index e29370a..ca95528 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -114,6 +114,7 @@ always += xdp_tx_iptunnel_kern.o always += test_map_in_map_kern.o always += cookie_uid_helper_example.o always += tcp_synrto_kern.o +always += tcp_rwnd_kern.o HOSTCFLAGS += -I$(objtree)/usr/include HOSTCFLAGS += -I$(srctree)/tools/lib/ diff --git a/samples/bpf/tcp_rwnd_kern.c b/samples/bpf/tcp_rwnd_kern.c new file mode 100644 index 0000000..5daa649 --- /dev/null +++ b/samples/bpf/tcp_rwnd_kern.c @@ -0,0 +1,61 @@ +/* Copyright (c) 2017 Facebook + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + * + * BPF program to set initial receive window to 40 packets when using IPv6 + * and the first 5.5 bytes of the IPv6 addresses are not the same (in this + * example that means both hosts are not the same datacenter. + */ + +#include +#include +#include +#include +#include +#include "bpf_helpers.h" + +#define DEBUG 1 + +SEC("sockops") +int bpf_rwnd(struct bpf_sock_ops *skops) +{ + char fmt1[] = "BPF command: %d\n"; + char fmt2[] = " Returning %d\n"; + int rv = -1; + int op; + + /* For testing purposes, only execute rest of BPF program + * if neither port numberis 55601 + */ + if (skops->remote_port != 55601 && skops->local_port != 55601) + return -1; + + op = (int) skops->op; + +#ifdef DEBUG + bpf_trace_printk(fmt1, sizeof(fmt1), op); +#endif + + /* Check for RWND_INIT operation and IPv6 addresses */ + if (op == BPF_SOCK_OPS_RWND_INIT && + skops->family == AF_INET6) { + + /* If the first 5.5 bytes of the IPv6 address are not the same + * then both hosts are not in the same datacenter + * so use a larger initial advertized window (40 packets) + */ + if (skops->local_ip6[0] != skops->remote_ip6[0] || + (skops->local_ip6[1] & 0xfffff000) != + (skops->remote_ip6[1] & 0xfffff000)) + bpf_trace_printk(fmt2, sizeof(fmt2), -1); + rv = 40; + } +#ifdef DEBUG + bpf_trace_printk(fmt2, sizeof(fmt2), rv); +#endif + skops->reply = rv; + return 1; +} +char _license[] SEC("license") = "GPL"; -- 2.9.3