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 "bpftool cgroup attach $cg sock_ops $prog" 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/bpf_helpers.h> |
19 | #include <bpf/bpf_endian.h> |
20 | |
21 | #define DEBUG 1 |
22 | |
23 | SEC("sockops" ) |
24 | int bpf_basertt(struct bpf_sock_ops *skops) |
25 | { |
26 | char [sizeof(struct ipv6hdr)]; |
27 | struct ipv6hdr *hdr6; |
28 | struct iphdr *hdr; |
29 | int hdr_size = 0; |
30 | int save_syn = 1; |
31 | int tos = 0; |
32 | int rv = 0; |
33 | int op; |
34 | |
35 | op = (int) skops->op; |
36 | |
37 | #ifdef DEBUG |
38 | bpf_printk("BPF command: %d\n" , op); |
39 | #endif |
40 | switch (op) { |
41 | case BPF_SOCK_OPS_TCP_LISTEN_CB: |
42 | rv = bpf_setsockopt(skops, SOL_TCP, TCP_SAVE_SYN, |
43 | &save_syn, sizeof(save_syn)); |
44 | break; |
45 | case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: |
46 | if (skops->family == AF_INET) |
47 | hdr_size = sizeof(struct iphdr); |
48 | else |
49 | hdr_size = sizeof(struct ipv6hdr); |
50 | rv = bpf_getsockopt(skops, SOL_TCP, TCP_SAVED_SYN, |
51 | header, hdr_size); |
52 | if (!rv) { |
53 | if (skops->family == AF_INET) { |
54 | hdr = (struct iphdr *) header; |
55 | tos = hdr->tos; |
56 | if (tos != 0) |
57 | bpf_setsockopt(skops, SOL_IP, IP_TOS, |
58 | &tos, sizeof(tos)); |
59 | } else { |
60 | hdr6 = (struct ipv6hdr *) header; |
61 | tos = ((hdr6->priority) << 4 | |
62 | (hdr6->flow_lbl[0]) >> 4); |
63 | if (tos) |
64 | bpf_setsockopt(skops, SOL_IPV6, |
65 | IPV6_TCLASS, |
66 | &tos, sizeof(tos)); |
67 | } |
68 | rv = 0; |
69 | } |
70 | break; |
71 | default: |
72 | rv = -1; |
73 | } |
74 | #ifdef DEBUG |
75 | bpf_printk("Returning %d\n" , rv); |
76 | #endif |
77 | skops->reply = rv; |
78 | return 1; |
79 | } |
80 | char _license[] SEC("license" ) = "GPL" ; |
81 | |