1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (c) 2018 Facebook
5 * BPF program to automatically reflect TOS option from received syn packet
7 * Use load_sock_ops to load this BPF program.
10 #include <uapi/linux/bpf.h>
11 #include <uapi/linux/tcp.h>
12 #include <uapi/linux/if_ether.h>
13 #include <uapi/linux/if_packet.h>
14 #include <uapi/linux/ip.h>
15 #include <uapi/linux/ipv6.h>
16 #include <uapi/linux/in.h>
17 #include <linux/socket.h>
18 #include "bpf_helpers.h"
19 #include "bpf_endian.h"
23 #define bpf_printk(fmt, ...) \
25 char ____fmt[] = fmt; \
26 bpf_trace_printk(____fmt, sizeof(____fmt), \
31 int bpf_basertt(struct bpf_sock_ops *skops)
33 char header[sizeof(struct ipv6hdr)];
45 bpf_printk("BPF command: %d\n", op);
48 case BPF_SOCK_OPS_TCP_LISTEN_CB:
49 rv = bpf_setsockopt(skops, SOL_TCP, TCP_SAVE_SYN,
50 &save_syn, sizeof(save_syn));
52 case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
53 if (skops->family == AF_INET)
54 hdr_size = sizeof(struct iphdr);
56 hdr_size = sizeof(struct ipv6hdr);
57 rv = bpf_getsockopt(skops, SOL_TCP, TCP_SAVED_SYN,
60 if (skops->family == AF_INET) {
61 hdr = (struct iphdr *) header;
64 bpf_setsockopt(skops, SOL_IP, IP_TOS,
67 hdr6 = (struct ipv6hdr *) header;
68 tos = ((hdr6->priority) << 4 |
69 (hdr6->flow_lbl[0]) >> 4);
71 bpf_setsockopt(skops, SOL_IPV6,
82 bpf_printk("Returning %d\n", rv);
87 char _license[] SEC("license") = "GPL";