| Nikita V. Shirokov | acb4ea9 | 2018-08-30 07:51:54 -0700 | [diff] [blame^] | 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 | |
| 30 | SEC("sockops") |
| 31 | int 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 | } |
| 87 | char _license[] SEC("license") = "GPL"; |