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- // 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/bpf_helpers.h>
- #include <bpf/bpf_endian.h>
- #define DEBUG 1
- 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";
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