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linux-sg2042/samples/bpf/tcp_rwnd_kern.c

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bpf: Sample bpf program to set initial window The sample bpf program, tcp_rwnd_kern.c, sets the initial advertized window to 40 packets in an environment where distinct IPv6 prefixes indicate that both hosts are not in the same data center. Signed-off-by: Lawrence Brakmo <brakmo@fb.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-01 11:02:45 +08:00
/* Copyright (c) 2017 Facebook
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*
* BPF program to set initial receive window to 40 packets when using IPv6
* and the first 5.5 bytes of the IPv6 addresses are not the same (in this
* example that means both hosts are not the same datacenter).
*
samples: bpf: remove load_sock_ops in favour of bpftool bpftool can do all the things load_sock_ops used to do, and more. Point users to bpftool instead of maintaining this sample utility. Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-02-28 11:04:11 +08:00
* Use "bpftool cgroup attach $cg sock_ops $prog" to load this BPF program.
bpf: Sample bpf program to set initial window The sample bpf program, tcp_rwnd_kern.c, sets the initial advertized window to 40 packets in an environment where distinct IPv6 prefixes indicate that both hosts are not in the same data center. Signed-off-by: Lawrence Brakmo <brakmo@fb.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-01 11:02:45 +08:00
*/
#include <uapi/linux/bpf.h>
#include <uapi/linux/if_ether.h>
#include <uapi/linux/if_packet.h>
#include <uapi/linux/ip.h>
#include <linux/socket.h>
#include "bpf_helpers.h"
#include "bpf_endian.h"
#define DEBUG 1
SEC("sockops")
int bpf_rwnd(struct bpf_sock_ops *skops)
{
int rv = -1;
int op;
/* For testing purposes, only execute rest of BPF program
* if neither port numberis 55601
*/
if (bpf_ntohl(skops->remote_port) !=
bpf: Fix tcp_rwnd_kern.c sample program The program was returning -1 in some cases which is not allowed by the verifier any longer. Fixes: 390ee7e29fc8 ("bpf: enforce return code for cgroup-bpf programs") Signed-off-by: Lawrence Brakmo <brakmo@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-11-11 14:19:51 +08:00
55601 && skops->local_port != 55601) {
skops->reply = -1;
return 1;
}
bpf: Sample bpf program to set initial window The sample bpf program, tcp_rwnd_kern.c, sets the initial advertized window to 40 packets in an environment where distinct IPv6 prefixes indicate that both hosts are not in the same data center. Signed-off-by: Lawrence Brakmo <brakmo@fb.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-01 11:02:45 +08:00
op = (int) skops->op;
#ifdef DEBUG
bpf_printk("BPF command: %d\n", op);
#endif
/* Check for RWND_INIT operation and IPv6 addresses */
if (op == BPF_SOCK_OPS_RWND_INIT &&
skops->family == AF_INET6) {
/* If the first 5.5 bytes of the IPv6 address are not the same
* then both hosts are not in the same datacenter
* so use a larger initial advertized window (40 packets)
*/
if (skops->local_ip6[0] != skops->remote_ip6[0] ||
(bpf_ntohl(skops->local_ip6[1]) & 0xfffff000) !=
(bpf_ntohl(skops->remote_ip6[1]) & 0xfffff000))
rv = 40;
}
#ifdef DEBUG
bpf_printk("Returning %d\n", rv);
#endif
skops->reply = rv;
return 1;
}
char _license[] SEC("license") = "GPL";