| 1 | // SPDX-License-Identifier: GPL-2.0 |
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| 2 | /* Copyright (c) 2021 Facebook */ |
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| 3 | #include "bpf_iter.h" |
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| 4 | #include "bpf_tracing_net.h" |
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| 5 | #include <bpf/bpf_helpers.h> |
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| 6 | #include <bpf/bpf_endian.h> |
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| 7 | |
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| 8 | #define bpf_tcp_sk(skc) ({ \ |
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| 9 | struct sock_common *_skc = skc; \ |
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| 10 | sk = NULL; \ |
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| 11 | tp = NULL; \ |
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| 12 | if (_skc) { \ |
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| 13 | tp = bpf_skc_to_tcp_sock(_skc); \ |
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| 14 | sk = (struct sock *)tp; \ |
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| 15 | } \ |
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| 16 | tp; \ |
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| 17 | }) |
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| 18 | |
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| 19 | unsigned short reuse_listen_hport = 0; |
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| 20 | unsigned short listen_hport = 0; |
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| 21 | char cubic_cc[TCP_CA_NAME_MAX] = "bpf_cubic" ; |
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| 22 | char dctcp_cc[TCP_CA_NAME_MAX] = "bpf_dctcp" ; |
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| 23 | bool random_retry = false; |
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| 24 | |
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| 25 | static bool tcp_cc_eq(const char *a, const char *b) |
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| 26 | { |
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| 27 | int i; |
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| 28 | |
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| 29 | for (i = 0; i < TCP_CA_NAME_MAX; i++) { |
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| 30 | if (a[i] != b[i]) |
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| 31 | return false; |
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| 32 | if (!a[i]) |
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| 33 | break; |
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| 34 | } |
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| 35 | |
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| 36 | return true; |
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| 37 | } |
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| 38 | |
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| 39 | SEC("iter/tcp" ) |
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| 40 | int change_tcp_cc(struct bpf_iter__tcp *ctx) |
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| 41 | { |
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| 42 | char cur_cc[TCP_CA_NAME_MAX]; |
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| 43 | struct tcp_sock *tp; |
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| 44 | struct sock *sk; |
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| 45 | |
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| 46 | if (!bpf_tcp_sk(ctx->sk_common)) |
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| 47 | return 0; |
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| 48 | |
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| 49 | if (sk->sk_family != AF_INET6 || |
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| 50 | (sk->sk_state != TCP_LISTEN && |
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| 51 | sk->sk_state != TCP_ESTABLISHED) || |
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| 52 | (sk->sk_num != reuse_listen_hport && |
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| 53 | sk->sk_num != listen_hport && |
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| 54 | bpf_ntohs(sk->sk_dport) != listen_hport)) |
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| 55 | return 0; |
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| 56 | |
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| 57 | if (bpf_getsockopt(tp, SOL_TCP, TCP_CONGESTION, |
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| 58 | cur_cc, sizeof(cur_cc))) |
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| 59 | return 0; |
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| 60 | |
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| 61 | if (!tcp_cc_eq(cur_cc, cubic_cc)) |
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| 62 | return 0; |
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| 63 | |
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| 64 | if (random_retry && bpf_get_prandom_u32() % 4 == 1) |
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| 65 | return 1; |
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| 66 | |
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| 67 | bpf_setsockopt(tp, SOL_TCP, TCP_CONGESTION, dctcp_cc, sizeof(dctcp_cc)); |
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| 68 | return 0; |
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| 69 | } |
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| 70 | |
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| 71 | char _license[] SEC("license" ) = "GPL" ; |
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| 72 | |
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