cregit-Linux how code gets into the kernel

Release 4.14 samples/bpf/tcp_synrto_kern.c

Directory: samples/bpf
/* 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 SYN and SYN-ACK RTOs to 10ms when using IPv6 addresses
 * and the first 5.5 bytes of the IPv6 addresses are the same (in this example
 * that means both hosts are in the same datacenter).
 *
 * Use load_sock_ops to load this BPF program.
 */

#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


#define bpf_printk(fmt, ...)					\
({                                                              \
               char ____fmt[] = fmt;                            \
               bpf_trace_printk(____fmt, sizeof(____fmt),       \
                                ##__VA_ARGS__);                 \
})

SEC("sockops")

int bpf_synrto(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) != 55601 && skops->local_port != 55601) return -1; op = (int) skops->op; #ifdef DEBUG bpf_printk("BPF command: %d\n", op); #endif /* Check for TIMEOUT_INIT operation and IPv6 addresses */ if (op == BPF_SOCK_OPS_TIMEOUT_INIT && skops->family == AF_INET6) { /* If the first 5.5 bytes of the IPv6 address are the same * then both hosts are in the same datacenter * so use an RTO of 10ms */ if (skops->local_ip6[0] == skops->remote_ip6[0] && (bpf_ntohl(skops->local_ip6[1]) & 0xfff00000) == (bpf_ntohl(skops->remote_ip6[1]) & 0xfff00000)) rv = 10; } #ifdef DEBUG bpf_printk("Returning %d\n", rv); #endif skops->reply = rv; return 1; }

Contributors

PersonTokensPropCommitsCommitProp
Lawrence Brakmo147100.00%1100.00%
Total147100.00%1100.00%

char _license[] SEC("license") = "GPL";

Overall Contributors

PersonTokensPropCommitsCommitProp
Lawrence Brakmo197100.00%1100.00%
Total197100.00%1100.00%
Directory: samples/bpf
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