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<ol class="chapter"><li class="chapter-item expanded affix "><li class="part-title">eBPF 实践教程：基于 libbpf 和 CO-RE</li><li class="chapter-item expanded "><a href="../0-introduce/index.html"><strong aria-hidden="true">1.</strong> 介绍 eBPF 的基本概念、常见的开发工具</a></li><li class="chapter-item expanded "><a href="../1-helloworld/index.html"><strong aria-hidden="true">2.</strong> eBPF Hello World，基本框架和开发流程</a></li><li class="chapter-item expanded "><a href="../2-kprobe-unlink/index.html"><strong aria-hidden="true">3.</strong> 使用 kprobe 监测捕获 unlink 系统调用</a></li><li class="chapter-item expanded "><a href="../3-fentry-unlink/index.html"><strong aria-hidden="true">4.</strong> 使用 fentry 监测捕获 unlink 系统调用</a></li><li class="chapter-item expanded "><a href="../4-opensnoop/index.html"><strong aria-hidden="true">5.</strong> 捕获进程打开文件的系统调用集合，使用全局变量过滤进程 pid</a></li><li class="chapter-item expanded "><a href="../5-uprobe-bashreadline/index.html"><strong aria-hidden="true">6.</strong> 使用 uprobe 捕获 bash 的 readline 函数调用</a></li><li class="chapter-item expanded "><a href="../6-sigsnoop/index.html"><strong aria-hidden="true">7.</strong> 捕获进程发送信号的系统调用集合，使用 hash map 保存状态</a></li><li class="chapter-item expanded "><a href="../7-execsnoop/index.html"><strong aria-hidden="true">8.</strong> 捕获进程执行/退出时间，通过 perf event array 向用户态打印输出</a></li><li class="chapter-item expanded "><a href="../8-exitsnoop/index.html"><strong aria-hidden="true">9.</strong> 使用 exitsnoop 监控进程退出事件，使用 ring buffer 向用户态打印输出</a></li><li class="chapter-item expanded "><a href="../9-runqlat/index.html"><strong aria-hidden="true">10.</strong> 一个 Linux 内核 BPF 程序，通过柱状图来总结调度程序运行队列延迟，显示任务等待运行在 CPU 上的时间长度</a></li><li class="chapter-item expanded "><a href="../10-hardirqs/index.html"><strong aria-hidden="true">11.</strong> 使用 hardirqs 或 softirqs 捕获中断事件</a></li><li class="chapter-item expanded "><a href="../11-bootstrap/index.html"><strong aria-hidden="true">12.</strong> 使用 bootstrap 开发用户态程序并跟踪 exec() 和 exit() 系统调用</a></li><li class="chapter-item expanded "><a href="../13-tcpconnlat/index.html"><strong aria-hidden="true">13.</strong> 使用 libbpf-bootstrap 开发程序统计 TCP 连接延时</a></li><li class="chapter-item expanded "><a href="../14-tcpstates/index.html"><strong aria-hidden="true">14.</strong> 使用 libbpf-bootstrap 记录 TCP 连接状态与 TCP RTT</a></li><li class="chapter-item expanded "><a href="../15-javagc/index.html"><strong aria-hidden="true">15.</strong> 使用 USDT 捕获用户态 Java GC 事件耗时</a></li><li class="chapter-item expanded "><a href="../16-memleak/index.html"><strong aria-hidden="true">16.</strong> 编写 eBPF 程序 Memleak 监控内存泄漏</a></li><li class="chapter-item expanded "><a href="../17-biopattern/index.html"><strong aria-hidden="true">17.</strong> 编写 eBPF 程序 Biopattern 统计随机/顺序磁盘 I/O</a></li><li class="chapter-item expanded "><a href="../18-further-reading/index.html"><strong aria-hidden="true">18.</strong> 更多的参考资料</a></li><li class="chapter-item expanded "><a href="../19-lsm-connect/index.html"><strong aria-hidden="true">19.</strong> 使用 LSM 进行安全检测防御</a></li><li class="chapter-item expanded "><a href="../20-tc/index.html"><strong aria-hidden="true">20.</strong> 使用 eBPF 进行 tc 流量控制</a></li><li class="chapter-item expanded affix "><li class="part-title">eBPF 高级特性与进阶主题</li><li class="chapter-item expanded "><a href="../22-android/index.html"><strong aria-hidden="true">21.</strong> 在 Android 上使用 eBPF 程序</a></li><li class="chapter-item expanded "><a href="../23-http/index.html"><strong aria-hidden="true">22.</strong> 使用 eBPF 追踪 HTTP 请求或其他七层协议</a></li><li class="chapter-item expanded "><a href="../30-sslsniff/index.html"><strong aria-hidden="true">23.</strong> 使用 uprobe 捕获多种库的 SSL/TLS 明文数据</a></li><li class="chapter-item expanded "><a href="../29-sockops/index.html" class="active"><strong aria-hidden="true">24.</strong> 使用 sockops 加速网络请求转发</a></li><li class="chapter-item expanded "><a href="../24-hide/index.html"><strong aria-hidden="true">25.</strong> 使用 eBPF 隐藏进程或文件信息</a></li><li class="chapter-item expanded "><a href="../25-signal/index.html"><strong aria-hidden="true">26.</strong> 使用 bpf_send_signal 发送信号终止进程</a></li><li class="chapter-item expanded "><a href="../26-sudo/index.html"><strong aria-hidden="true">27.</strong> 使用 eBPF 添加 sudo 用户</a></li><li class="chapter-item expanded "><a href="../27-replace/index.html"><strong aria-hidden="true">28.</strong> 使用 eBPF 替换任意程序读取或写入的文本</a></li><li class="chapter-item expanded "><a href="../28-detach/index.html"><strong aria-hidden="true">29.</strong> BPF的生命周期：使用 Detached 模式在用户态应用退出后持续运行 eBPF 程序</a></li><li class="chapter-item expanded "><a href="../30-sslsniff/index.html"><strong aria-hidden="true">30.</strong> 使用 eBPF 用户态捕获多种库的 SSL/TLS 明文数据</a></li><li class="chapter-item expanded affix "><li class="part-title">bcc tutorial</li><li class="chapter-item expanded "><a href="../bcc-documents/kernel-versions.html"><strong aria-hidden="true">31.</strong> BPF Features by Linux Kernel Version</a></li><li class="chapter-item expanded "><a href="../bcc-documents/kernel_config.html"><strong aria-hidden="true">32.</strong> Kernel Configuration for BPF Features</a></li><li class="chapter-item expanded "><a href="../bcc-documents/reference_guide.html"><strong aria-hidden="true">33.</strong> bcc Reference Guide</a></li><li class="chapter-item expanded "><a href="../bcc-documents/special_filtering.html"><strong aria-hidden="true">34.</strong> Special Filtering</a></li><li class="chapter-item expanded "><a href="../bcc-documents/tutorial.html"><strong aria-hidden="true">35.</strong> bcc Tutorial</a></li><li class="chapter-item expanded "><a href="../bcc-documents/tutorial_bcc_python_developer.html"><strong aria-hidden="true">36.</strong> bcc Python Developer Tutorial</a></li></ol>
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<h1 id="ebpf-sockops-示例"><a class="header" href="#ebpf-sockops-示例">eBPF sockops 示例</a></h1>
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<h2 id="利用-ebpf-的-sockops-进行性能优化"><a class="header" href="#利用-ebpf-的-sockops-进行性能优化">利用 eBPF 的 sockops 进行性能优化</a></h2>
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<p>网络连接本质上是 socket 之间的通讯，eBPF 提供了一个 <a href="https://man7.org/linux/man-pages/man7/bpf-helpers.7.html">bpf_msg_redirect_hash</a> 函数，用来将应用发出的包直接转发到对端的 socket，可以极大地加速包在内核中的处理流程。</p>
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<p>这里 sock_map 是记录 socket 规则的关键部分，即根据当前的数据包信息，从 sock_map 中挑选一个存在的 socket 连接来转发请求。所以需要先在 sockops 的 hook 处或者其它地方，将 socket 信息保存到 sock_map，并提供一个规则 (一般为四元组) 根据 key 查找到 socket。</p>
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<p>Merbridge 项目就是这样实现了用 eBPF 代替 iptables 为 Istio 进行加速。在使用 Merbridge (eBPF) 优化之后，出入口流量会直接跳过很多内核模块，明显提高性能，如下图所示：</p>
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<p><img src="merbridge.png" alt="merbridge" /></p>
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<h2 id="运行样例"><a class="header" href="#运行样例">运行样例</a></h2>
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<p>此示例程序从发送者的套接字（出口）重定向流量至接收者的套接字（入口），<strong>跳过 TCP/IP 内核网络栈</strong>。在这个示例中，我们假定发送者和接收者都在<strong>同一台</strong>机器上运行。</p>
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<h3 id="编译-ebpf-程序"><a class="header" href="#编译-ebpf-程序">编译 eBPF 程序</a></h3>
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<pre><code class="language-shell"># Compile the bpf_sockops program
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clang -O2 -g -Wall -target bpf -c bpf_sockops.c -o bpf_sockops.o
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clang -O2 -g -Wall -target bpf -c bpf_redir.c -o bpf_redir.o
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</code></pre>
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<h3 id="加载-ebpf-程序"><a class="header" href="#加载-ebpf-程序">加载 eBPF 程序</a></h3>
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<pre><code class="language-shell">sudo ./load.sh
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</code></pre>
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<p>您可以使用 <a href="https://github.com/torvalds/linux/blob/master/tools/bpf/bpftool/Documentation/bpftool-prog.rst">bpftool utility</a> 检查这两个 eBPF 程序是否已经加载。</p>
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<pre><code class="language-console">$ sudo bpftool prog show
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63: sock_ops name bpf_sockmap tag 275467be1d69253d gpl
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loaded_at 2019-01-24T13:07:17+0200 uid 0
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xlated 1232B jited 750B memlock 4096B map_ids 58
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64: sk_msg name bpf_redir tag bc78074aa9dd96f4 gpl
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loaded_at 2019-01-24T13:07:17+0200 uid 0
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xlated 304B jited 233B memlock 4096B map_ids 58
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</code></pre>
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<h3 id="运行-iperf3-服务器"><a class="header" href="#运行-iperf3-服务器">运行 <a href="https://iperf.fr/">iperf3</a> 服务器</a></h3>
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<pre><code class="language-shell">iperf3 -s -p 10000
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</code></pre>
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<h3 id="运行-iperf3-客户端"><a class="header" href="#运行-iperf3-客户端">运行 <a href="https://iperf.fr/">iperf3</a> 客户端</a></h3>
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<pre><code class="language-shell">iperf3 -c 127.0.0.1 -t 10 -l 64k -p 10000
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</code></pre>
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<h3 id="收集追踪"><a class="header" href="#收集追踪">收集追踪</a></h3>
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<pre><code class="language-console">$ ./trace.sh
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iperf3-9516 [001] .... 22500.634108: 0: <<< ipv4 op = 4, port 18583 --> 4135
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iperf3-9516 [001] ..s1 22500.634137: 0: <<< ipv4 op = 5, port 4135 --> 18583
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iperf3-9516 [001] .... 22500.634523: 0: <<< ipv4 op = 4, port 19095 --> 4135
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iperf3-9516 [001] ..s1 22500.634536: 0: <<< ipv4 op = 5, port 4135 --> 19095
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</code></pre>
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<p>你应该可以看到 4 个用于套接字建立的事件。如果你没有看到任何事件，那么 eBPF 程序可能没有正确地附加上。</p>
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<h3 id="卸载-ebpf-程序"><a class="header" href="#卸载-ebpf-程序">卸载 eBPF 程序</a></h3>
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<pre><code class="language-shell">sudo ./unload.sh
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</code></pre>
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<h2 id="参考资料"><a class="header" href="#参考资料">参考资料</a></h2>
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<ul>
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<li><a href="https://github.com/zachidan/ebpf-sockops">https://github.com/zachidan/ebpf-sockops</a></li>
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<li><a href="https://github.com/merbridge/merbridge">https://github.com/merbridge/merbridge</a></li>
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</html>
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