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78 lines
1.9 KiB
78 lines
1.9 KiB
/* Copyright (c) 2017 Facebook |
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* |
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* This program is free software; you can redistribute it and/or |
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* modify it under the terms of version 2 of the GNU General Public |
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* License as published by the Free Software Foundation. |
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* |
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* BPF program to set congestion control to dctcp when both hosts are |
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* in the same datacenter (as deteremined by IPv6 prefix). |
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* |
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* Use "bpftool cgroup attach $cg sock_ops $prog" to load this BPF program. |
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*/ |
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#include <uapi/linux/bpf.h> |
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#include <uapi/linux/tcp.h> |
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#include <uapi/linux/if_ether.h> |
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#include <uapi/linux/if_packet.h> |
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#include <uapi/linux/ip.h> |
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#include <linux/socket.h> |
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#include <bpf/bpf_helpers.h> |
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#include <bpf/bpf_endian.h> |
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#define DEBUG 1 |
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SEC("sockops") |
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int bpf_cong(struct bpf_sock_ops *skops) |
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{ |
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char cong[] = "dctcp"; |
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int rv = 0; |
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int op; |
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/* For testing purposes, only execute rest of BPF program |
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* if neither port numberis 55601 |
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*/ |
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if (bpf_ntohl(skops->remote_port) != 55601 && |
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skops->local_port != 55601) { |
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skops->reply = -1; |
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return 1; |
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} |
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op = (int) skops->op; |
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#ifdef DEBUG |
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bpf_printk("BPF command: %d\n", op); |
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#endif |
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/* Check if both hosts are in the same datacenter. For this |
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* example they are if the 1st 5.5 bytes in the IPv6 address |
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* are the same. |
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*/ |
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if (skops->family == AF_INET6 && |
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skops->local_ip6[0] == skops->remote_ip6[0] && |
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(bpf_ntohl(skops->local_ip6[1]) & 0xfff00000) == |
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(bpf_ntohl(skops->remote_ip6[1]) & 0xfff00000)) { |
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switch (op) { |
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case BPF_SOCK_OPS_NEEDS_ECN: |
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rv = 1; |
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break; |
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case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB: |
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rv = bpf_setsockopt(skops, SOL_TCP, TCP_CONGESTION, |
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cong, sizeof(cong)); |
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break; |
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case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: |
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rv = bpf_setsockopt(skops, SOL_TCP, TCP_CONGESTION, |
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cong, sizeof(cong)); |
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break; |
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default: |
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rv = -1; |
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} |
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} else { |
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rv = -1; |
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} |
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#ifdef DEBUG |
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bpf_printk("Returning %d\n", rv); |
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#endif |
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skops->reply = rv; |
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return 1; |
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} |
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char _license[] SEC("license") = "GPL";
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