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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 | * | |
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"; |