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 initial congestion window and initial receive |
8 | * window to 40 packets and send and receive buffers to 1.5MB. This |
9 | * would usually be done after doing appropriate checks that indicate |
10 | * the hosts are far enough away (i.e. large RTT). |
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_iw(struct bpf_sock_ops *skops) |
27 | { |
28 | int bufsize = 1500000; |
29 | int rwnd_init = 40; |
30 | int iw = 40; |
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 && |
38 | skops->local_port != 55601) { |
39 | skops->reply = -1; |
40 | return 1; |
41 | } |
42 | |
43 | op = (int) skops->op; |
44 | |
45 | #ifdef DEBUG |
46 | bpf_printk("BPF command: %d\n" , op); |
47 | #endif |
48 | |
49 | /* Usually there would be a check to insure the hosts are far |
50 | * from each other so it makes sense to increase buffer sizes |
51 | */ |
52 | switch (op) { |
53 | case BPF_SOCK_OPS_RWND_INIT: |
54 | rv = rwnd_init; |
55 | break; |
56 | case BPF_SOCK_OPS_TCP_CONNECT_CB: |
57 | /* Set sndbuf and rcvbuf of active connections */ |
58 | rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize, |
59 | sizeof(bufsize)); |
60 | rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF, |
61 | &bufsize, sizeof(bufsize)); |
62 | break; |
63 | case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB: |
64 | rv = bpf_setsockopt(skops, SOL_TCP, TCP_BPF_IW, &iw, |
65 | sizeof(iw)); |
66 | break; |
67 | case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: |
68 | /* Set sndbuf and rcvbuf of passive connections */ |
69 | rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize, |
70 | sizeof(bufsize)); |
71 | rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF, |
72 | &bufsize, sizeof(bufsize)); |
73 | break; |
74 | default: |
75 | rv = -1; |
76 | } |
77 | #ifdef DEBUG |
78 | bpf_printk("Returning %d\n" , rv); |
79 | #endif |
80 | skops->reply = rv; |
81 | return 1; |
82 | } |
83 | char _license[] SEC("license" ) = "GPL" ; |
84 | |