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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 | * | |
ea9b6362 | 12 | * Use "bpftool cgroup attach $cg sock_ops $prog" to load this BPF program. |
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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> | |
7cf245a3 THJ |
20 | #include <bpf/bpf_helpers.h> |
21 | #include <bpf/bpf_endian.h> | |
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22 | |
23 | #define DEBUG 1 | |
24 | ||
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25 | SEC("sockops") |
26 | int bpf_clamp(struct bpf_sock_ops *skops) | |
27 | { | |
28 | int bufsize = 150000; | |
29 | int to_init = 10; | |
30 | int clamp = 100; | |
31 | int rv = 0; | |
32 | int op; | |
33 | ||
34 | /* For testing purposes, only execute rest of BPF program | |
35 | * if neither port numberis 55601 | |
36 | */ | |
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37 | if (bpf_ntohl(skops->remote_port) != 55601 && skops->local_port != 55601) { |
38 | skops->reply = -1; | |
39 | return 0; | |
40 | } | |
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41 | |
42 | op = (int) skops->op; | |
43 | ||
44 | #ifdef DEBUG | |
45 | bpf_printk("BPF command: %d\n", op); | |
46 | #endif | |
47 | ||
48 | /* Check that both hosts are within same datacenter. For this example | |
49 | * it is the case when the first 5.5 bytes of their IPv6 addresses are | |
50 | * the same. | |
51 | */ | |
52 | if (skops->family == AF_INET6 && | |
53 | skops->local_ip6[0] == skops->remote_ip6[0] && | |
54 | (bpf_ntohl(skops->local_ip6[1]) & 0xfff00000) == | |
55 | (bpf_ntohl(skops->remote_ip6[1]) & 0xfff00000)) { | |
56 | switch (op) { | |
57 | case BPF_SOCK_OPS_TIMEOUT_INIT: | |
58 | rv = to_init; | |
59 | break; | |
60 | case BPF_SOCK_OPS_TCP_CONNECT_CB: | |
61 | /* Set sndbuf and rcvbuf of active connections */ | |
62 | rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, | |
63 | &bufsize, sizeof(bufsize)); | |
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64 | rv += bpf_setsockopt(skops, SOL_SOCKET, |
65 | SO_RCVBUF, &bufsize, | |
66 | sizeof(bufsize)); | |
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67 | break; |
68 | case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB: | |
69 | rv = bpf_setsockopt(skops, SOL_TCP, | |
70 | TCP_BPF_SNDCWND_CLAMP, | |
71 | &clamp, sizeof(clamp)); | |
72 | break; | |
73 | case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: | |
74 | /* Set sndbuf and rcvbuf of passive connections */ | |
75 | rv = bpf_setsockopt(skops, SOL_TCP, | |
76 | TCP_BPF_SNDCWND_CLAMP, | |
77 | &clamp, sizeof(clamp)); | |
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78 | rv += bpf_setsockopt(skops, SOL_SOCKET, |
79 | SO_SNDBUF, &bufsize, | |
80 | sizeof(bufsize)); | |
81 | rv += bpf_setsockopt(skops, SOL_SOCKET, | |
82 | SO_RCVBUF, &bufsize, | |
83 | sizeof(bufsize)); | |
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84 | break; |
85 | default: | |
86 | rv = -1; | |
87 | } | |
88 | } else { | |
89 | rv = -1; | |
90 | } | |
91 | #ifdef DEBUG | |
92 | bpf_printk("Returning %d\n", rv); | |
93 | #endif | |
94 | skops->reply = rv; | |
95 | return 1; | |
96 | } | |
97 | char _license[] SEC("license") = "GPL"; |