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/* Copyright (c) 2021 Facebook */
3#include <vmlinux.h>
4#include "bpf_tracing_net.h"
5#include <bpf/bpf_helpers.h>
6#include <bpf/bpf_endian.h>
7
8#define bpf_tcp_sk(skc) ({ \
9 struct sock_common *_skc = skc; \
10 sk = NULL; \
11 tp = NULL; \
12 if (_skc) { \
13 tp = bpf_skc_to_tcp_sock(_skc); \
14 sk = (struct sock *)tp; \
15 } \
16 tp; \
17})
18
19unsigned short reuse_listen_hport = 0;
20unsigned short listen_hport = 0;
21const char cubic_cc[] = "bpf_cubic";
22char dctcp_cc[TCP_CA_NAME_MAX] = "bpf_dctcp";
23bool random_retry = false;
24
25
26SEC("iter/tcp")
27int change_tcp_cc(struct bpf_iter__tcp *ctx)
28{
29 char cur_cc[TCP_CA_NAME_MAX];
30 struct tcp_sock *tp;
31 struct sock *sk;
32
33 if (!bpf_tcp_sk(ctx->sk_common))
34 return 0;
35
36 if (sk->sk_family != AF_INET6 ||
37 (sk->sk_state != TCP_LISTEN &&
38 sk->sk_state != TCP_ESTABLISHED) ||
39 (sk->sk_num != reuse_listen_hport &&
40 sk->sk_num != listen_hport &&
41 bpf_ntohs(sk->sk_dport) != listen_hport))
42 return 0;
43
44 if (bpf_getsockopt(tp, SOL_TCP, TCP_CONGESTION,
45 cur_cc, sizeof(cur_cc)))
46 return 0;
47
48 if (bpf_strncmp(cur_cc, TCP_CA_NAME_MAX, cubic_cc))
49 return 0;
50
51 if (random_retry && bpf_get_prandom_u32() % 4 == 1)
52 return 1;
53
54 bpf_setsockopt(tp, SOL_TCP, TCP_CONGESTION, dctcp_cc, sizeof(dctcp_cc));
55 return 0;
56}
57
58char _license[] SEC("license") = "GPL";