tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (c) 2018 Facebook
4 *
5 * BPF program to automatically reflect TOS option from received syn packet
6 *
7 * Use load_sock_ops to load this BPF program.
8 */
9
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"
20
21#define DEBUG 1
22
23#define bpf_printk(fmt, ...) \
24({ \
25 char ____fmt[] = fmt; \
26 bpf_trace_printk(____fmt, sizeof(____fmt), \
27 ##__VA_ARGS__); \
28})
29
30SEC("sockops")
31int bpf_basertt(struct bpf_sock_ops *skops)
32{
33 char header[sizeof(struct ipv6hdr)];
34 struct ipv6hdr *hdr6;
35 struct iphdr *hdr;
36 int hdr_size = 0;
37 int save_syn = 1;
38 int tos = 0;
39 int rv = 0;
40 int op;
41
42 op = (int) skops->op;
43
44#ifdef DEBUG
45 bpf_printk("BPF command: %d\n", op);
46#endif
47 switch (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));
51 break;
52 case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
53 if (skops->family == AF_INET)
54 hdr_size = sizeof(struct iphdr);
55 else
56 hdr_size = sizeof(struct ipv6hdr);
57 rv = bpf_getsockopt(skops, SOL_TCP, TCP_SAVED_SYN,
58 header, hdr_size);
59 if (!rv) {
60 if (skops->family == AF_INET) {
61 hdr = (struct iphdr *) header;
62 tos = hdr->tos;
63 if (tos != 0)
64 bpf_setsockopt(skops, SOL_IP, IP_TOS,
65 &tos, sizeof(tos));
66 } else {
67 hdr6 = (struct ipv6hdr *) header;
68 tos = ((hdr6->priority) << 4 |
69 (hdr6->flow_lbl[0]) >> 4);
70 if (tos)
71 bpf_setsockopt(skops, SOL_IPV6,
72 IPV6_TCLASS,
73 &tos, sizeof(tos));
74 }
75 rv = 0;
76 }
77 break;
78 default:
79 rv = -1;
80 }
81#ifdef DEBUG
82 bpf_printk("Returning %d\n", rv);
83#endif
84 skops->reply = rv;
85 return 1;
86}
87char _license[] SEC("license") = "GPL";