Lawrence Brakmo | c890063 | 2017-10-20 11:05:42 -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 | * BPF program to set base_rtt to 80us when host is running TCP-NV and |
| 8 | * both hosts are in the same datacenter (as determined by IPv6 prefix). |
| 9 | * |
Jakub Kicinski | ea9b636 | 2019-02-27 19:04:11 -0800 | [diff] [blame] | 10 | * Use "bpftool cgroup attach $cg sock_ops $prog" to load this BPF program. |
Lawrence Brakmo | c890063 | 2017-10-20 11:05:42 -0700 | [diff] [blame] | 11 | */ |
| 12 | |
| 13 | #include <uapi/linux/bpf.h> |
| 14 | #include <uapi/linux/tcp.h> |
| 15 | #include <uapi/linux/if_ether.h> |
| 16 | #include <uapi/linux/if_packet.h> |
| 17 | #include <uapi/linux/ip.h> |
| 18 | #include <linux/socket.h> |
| 19 | #include "bpf_helpers.h" |
| 20 | #include "bpf_endian.h" |
| 21 | |
| 22 | #define DEBUG 1 |
| 23 | |
Lawrence Brakmo | c890063 | 2017-10-20 11:05:42 -0700 | [diff] [blame] | 24 | SEC("sockops") |
| 25 | int bpf_basertt(struct bpf_sock_ops *skops) |
| 26 | { |
| 27 | char cong[20]; |
| 28 | char nv[] = "nv"; |
| 29 | int rv = 0, n; |
| 30 | int op; |
| 31 | |
| 32 | op = (int) skops->op; |
| 33 | |
| 34 | #ifdef DEBUG |
| 35 | bpf_printk("BPF command: %d\n", op); |
| 36 | #endif |
| 37 | |
| 38 | /* Check if both hosts are in the same datacenter. For this |
| 39 | * example they are if the 1st 5.5 bytes in the IPv6 address |
| 40 | * are the same. |
| 41 | */ |
| 42 | if (skops->family == AF_INET6 && |
| 43 | skops->local_ip6[0] == skops->remote_ip6[0] && |
| 44 | (bpf_ntohl(skops->local_ip6[1]) & 0xfff00000) == |
| 45 | (bpf_ntohl(skops->remote_ip6[1]) & 0xfff00000)) { |
| 46 | switch (op) { |
| 47 | case BPF_SOCK_OPS_BASE_RTT: |
| 48 | n = bpf_getsockopt(skops, SOL_TCP, TCP_CONGESTION, |
| 49 | cong, sizeof(cong)); |
| 50 | if (!n && !__builtin_memcmp(cong, nv, sizeof(nv)+1)) { |
| 51 | /* Set base_rtt to 80us */ |
| 52 | rv = 80; |
| 53 | } else if (n) { |
| 54 | rv = n; |
| 55 | } else { |
| 56 | rv = -1; |
| 57 | } |
| 58 | break; |
| 59 | default: |
| 60 | rv = -1; |
| 61 | } |
| 62 | } else { |
| 63 | rv = -1; |
| 64 | } |
| 65 | #ifdef DEBUG |
| 66 | bpf_printk("Returning %d\n", rv); |
| 67 | #endif |
| 68 | skops->reply = rv; |
| 69 | return 1; |
| 70 | } |
| 71 | char _license[] SEC("license") = "GPL"; |