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 "bpftool cgroup attach $cg sock_ops $prog" 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/bpf_helpers.h> |
21 | #include <bpf/bpf_endian.h> |
22 | |
23 | #define DEBUG 1 |
24 | |
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 | */ |
37 | if (bpf_ntohl(skops->remote_port) != 55601 && skops->local_port != 55601) { |
38 | skops->reply = -1; |
39 | return 0; |
40 | } |
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)); |
64 | rv += bpf_setsockopt(skops, SOL_SOCKET, |
65 | SO_RCVBUF, &bufsize, |
66 | sizeof(bufsize)); |
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)); |
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)); |
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" ; |
98 | |