| Lawrence Brakmo | 6c4a01b | 2017-06-30 20:02:54 -0700 | [diff] [blame] | 1 | /* Copyright (c) 2017 Facebook |
| 2 | * |
| 3 | * This program is free software; you can redistribute it and/or |
| 4 | * modify it under the terms of version 2 of the GNU General Public |
| 5 | * License as published by the Free Software Foundation. |
| 6 | * |
| 7 | * Sample BPF program to set send and receive buffers to 150KB, sndcwnd clamp |
| 8 | * to 100 packets and SYN and SYN_ACK RTOs to 10ms when both hosts are within |
| 9 | * the same datacenter. For his example, we assume they are within the same |
| 10 | * datacenter when the first 5.5 bytes of their IPv6 addresses are the same. |
| 11 | * |
| 12 | * Use load_sock_ops to load this BPF program. |
| 13 | */ |
| 14 | |
| 15 | #include <uapi/linux/bpf.h> |
| 16 | #include <uapi/linux/if_ether.h> |
| 17 | #include <uapi/linux/if_packet.h> |
| 18 | #include <uapi/linux/ip.h> |
| 19 | #include <linux/socket.h> |
| 20 | #include "bpf_helpers.h" |
| 21 | #include "bpf_endian.h" |
| 22 | |
| 23 | #define DEBUG 1 |
| 24 | |
| 25 | #define bpf_printk(fmt, ...) \ |
| 26 | ({ \ |
| 27 | char ____fmt[] = fmt; \ |
| 28 | bpf_trace_printk(____fmt, sizeof(____fmt), \ |
| 29 | ##__VA_ARGS__); \ |
| 30 | }) |
| 31 | |
| 32 | SEC("sockops") |
| 33 | int bpf_clamp(struct bpf_sock_ops *skops) |
| 34 | { |
| 35 | int bufsize = 150000; |
| 36 | int to_init = 10; |
| 37 | int clamp = 100; |
| 38 | int rv = 0; |
| 39 | int op; |
| 40 | |
| 41 | /* For testing purposes, only execute rest of BPF program |
| 42 | * if neither port numberis 55601 |
| 43 | */ |
| 44 | if (bpf_ntohl(skops->remote_port) != 55601 && skops->local_port != 55601) |
| 45 | return -1; |
| 46 | |
| 47 | op = (int) skops->op; |
| 48 | |
| 49 | #ifdef DEBUG |
| 50 | bpf_printk("BPF command: %d\n", op); |
| 51 | #endif |
| 52 | |
| 53 | /* Check that both hosts are within same datacenter. For this example |
| 54 | * it is the case when the first 5.5 bytes of their IPv6 addresses are |
| 55 | * the same. |
| 56 | */ |
| 57 | if (skops->family == AF_INET6 && |
| 58 | skops->local_ip6[0] == skops->remote_ip6[0] && |
| 59 | (bpf_ntohl(skops->local_ip6[1]) & 0xfff00000) == |
| 60 | (bpf_ntohl(skops->remote_ip6[1]) & 0xfff00000)) { |
| 61 | switch (op) { |
| 62 | case BPF_SOCK_OPS_TIMEOUT_INIT: |
| 63 | rv = to_init; |
| 64 | break; |
| 65 | case BPF_SOCK_OPS_TCP_CONNECT_CB: |
| 66 | /* Set sndbuf and rcvbuf of active connections */ |
| 67 | rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, |
| 68 | &bufsize, sizeof(bufsize)); |
| 69 | rv = rv*100 + bpf_setsockopt(skops, SOL_SOCKET, |
| 70 | SO_RCVBUF, &bufsize, |
| 71 | sizeof(bufsize)); |
| 72 | break; |
| 73 | case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB: |
| 74 | rv = bpf_setsockopt(skops, SOL_TCP, |
| 75 | TCP_BPF_SNDCWND_CLAMP, |
| 76 | &clamp, sizeof(clamp)); |
| 77 | break; |
| 78 | case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: |
| 79 | /* Set sndbuf and rcvbuf of passive connections */ |
| 80 | rv = bpf_setsockopt(skops, SOL_TCP, |
| 81 | TCP_BPF_SNDCWND_CLAMP, |
| 82 | &clamp, sizeof(clamp)); |
| 83 | rv = rv*100 + bpf_setsockopt(skops, SOL_SOCKET, |
| 84 | SO_SNDBUF, &bufsize, |
| 85 | sizeof(bufsize)); |
| 86 | rv = rv*100 + bpf_setsockopt(skops, SOL_SOCKET, |
| 87 | SO_RCVBUF, &bufsize, |
| 88 | sizeof(bufsize)); |
| 89 | break; |
| 90 | default: |
| 91 | rv = -1; |
| 92 | } |
| 93 | } else { |
| 94 | rv = -1; |
| 95 | } |
| 96 | #ifdef DEBUG |
| 97 | bpf_printk("Returning %d\n", rv); |
| 98 | #endif |
| 99 | skops->reply = rv; |
| 100 | return 1; |
| 101 | } |
| 102 | char _license[] SEC("license") = "GPL"; |