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80 lines
1.8 KiB
80 lines
1.8 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Copyright (c) 2018 Facebook |
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* |
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* BPF program to automatically reflect TOS option from received syn packet |
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* |
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* Use "bpftool cgroup attach $cg sock_ops $prog" to load this BPF program. |
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*/ |
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#include <uapi/linux/bpf.h> |
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#include <uapi/linux/tcp.h> |
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#include <uapi/linux/if_ether.h> |
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#include <uapi/linux/if_packet.h> |
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#include <uapi/linux/ip.h> |
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#include <uapi/linux/ipv6.h> |
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#include <uapi/linux/in.h> |
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#include <linux/socket.h> |
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#include <bpf/bpf_helpers.h> |
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#include <bpf/bpf_endian.h> |
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#define DEBUG 1 |
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SEC("sockops") |
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int bpf_basertt(struct bpf_sock_ops *skops) |
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{ |
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char header[sizeof(struct ipv6hdr)]; |
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struct ipv6hdr *hdr6; |
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struct iphdr *hdr; |
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int hdr_size = 0; |
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int save_syn = 1; |
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int tos = 0; |
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int rv = 0; |
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int op; |
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op = (int) skops->op; |
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#ifdef DEBUG |
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bpf_printk("BPF command: %d\n", op); |
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#endif |
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switch (op) { |
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case BPF_SOCK_OPS_TCP_LISTEN_CB: |
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rv = bpf_setsockopt(skops, SOL_TCP, TCP_SAVE_SYN, |
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&save_syn, sizeof(save_syn)); |
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break; |
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case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: |
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if (skops->family == AF_INET) |
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hdr_size = sizeof(struct iphdr); |
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else |
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hdr_size = sizeof(struct ipv6hdr); |
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rv = bpf_getsockopt(skops, SOL_TCP, TCP_SAVED_SYN, |
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header, hdr_size); |
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if (!rv) { |
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if (skops->family == AF_INET) { |
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hdr = (struct iphdr *) header; |
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tos = hdr->tos; |
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if (tos != 0) |
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bpf_setsockopt(skops, SOL_IP, IP_TOS, |
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&tos, sizeof(tos)); |
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} else { |
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hdr6 = (struct ipv6hdr *) header; |
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tos = ((hdr6->priority) << 4 | |
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(hdr6->flow_lbl[0]) >> 4); |
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if (tos) |
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bpf_setsockopt(skops, SOL_IPV6, |
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IPV6_TCLASS, |
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&tos, sizeof(tos)); |
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} |
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rv = 0; |
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} |
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break; |
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default: |
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rv = -1; |
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} |
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#ifdef DEBUG |
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bpf_printk("Returning %d\n", rv); |
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#endif |
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skops->reply = rv; |
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return 1; |
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} |
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char _license[] SEC("license") = "GPL";
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