88 lines
1.9 KiB
C
88 lines
1.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Copyright (c) 2018 Facebook
|
|
*
|
|
* BPF program to automatically reflect TOS option from received syn packet
|
|
*
|
|
* Use "bpftool cgroup attach $cg sock_ops $prog" to load this BPF program.
|
|
*/
|
|
|
|
#include <uapi/linux/bpf.h>
|
|
#include <uapi/linux/tcp.h>
|
|
#include <uapi/linux/if_ether.h>
|
|
#include <uapi/linux/if_packet.h>
|
|
#include <uapi/linux/ip.h>
|
|
#include <uapi/linux/ipv6.h>
|
|
#include <uapi/linux/in.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_basertt(struct bpf_sock_ops *skops)
|
|
{
|
|
char header[sizeof(struct ipv6hdr)];
|
|
struct ipv6hdr *hdr6;
|
|
struct iphdr *hdr;
|
|
int hdr_size = 0;
|
|
int save_syn = 1;
|
|
int tos = 0;
|
|
int rv = 0;
|
|
int op;
|
|
|
|
op = (int) skops->op;
|
|
|
|
#ifdef DEBUG
|
|
bpf_printk("BPF command: %d\n", op);
|
|
#endif
|
|
switch (op) {
|
|
case BPF_SOCK_OPS_TCP_LISTEN_CB:
|
|
rv = bpf_setsockopt(skops, SOL_TCP, TCP_SAVE_SYN,
|
|
&save_syn, sizeof(save_syn));
|
|
break;
|
|
case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
|
|
if (skops->family == AF_INET)
|
|
hdr_size = sizeof(struct iphdr);
|
|
else
|
|
hdr_size = sizeof(struct ipv6hdr);
|
|
rv = bpf_getsockopt(skops, SOL_TCP, TCP_SAVED_SYN,
|
|
header, hdr_size);
|
|
if (!rv) {
|
|
if (skops->family == AF_INET) {
|
|
hdr = (struct iphdr *) header;
|
|
tos = hdr->tos;
|
|
if (tos != 0)
|
|
bpf_setsockopt(skops, SOL_IP, IP_TOS,
|
|
&tos, sizeof(tos));
|
|
} else {
|
|
hdr6 = (struct ipv6hdr *) header;
|
|
tos = ((hdr6->priority) << 4 |
|
|
(hdr6->flow_lbl[0]) >> 4);
|
|
if (tos)
|
|
bpf_setsockopt(skops, SOL_IPV6,
|
|
IPV6_TCLASS,
|
|
&tos, sizeof(tos));
|
|
}
|
|
rv = 0;
|
|
}
|
|
break;
|
|
default:
|
|
rv = -1;
|
|
}
|
|
#ifdef DEBUG
|
|
bpf_printk("Returning %d\n", rv);
|
|
#endif
|
|
skops->reply = rv;
|
|
return 1;
|
|
}
|
|
char _license[] SEC("license") = "GPL";
|