1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2020, Tessares SA. */
3 /* Copyright (c) 2024, Kylin Software */
4
5 /* vmlinux.h, bpf_helpers.h and other 'define' */
6 #include "bpf_tracing_net.h"
7 #include "mptcp_bpf.h"
8
9 char _license[] SEC("license") = "GPL";
10
11 char cc[TCP_CA_NAME_MAX] = "reno";
12 int pid;
13
14 /* Associate a subflow counter to each token */
15 struct {
16 __uint(type, BPF_MAP_TYPE_HASH);
17 __uint(key_size, sizeof(__u32));
18 __uint(value_size, sizeof(__u32));
19 __uint(max_entries, 100);
20 } mptcp_sf SEC(".maps");
21
22 SEC("sockops")
mptcp_subflow(struct bpf_sock_ops * skops)23 int mptcp_subflow(struct bpf_sock_ops *skops)
24 {
25 __u32 init = 1, key, mark, *cnt;
26 struct mptcp_sock *msk;
27 struct bpf_sock *sk;
28 int err;
29
30 if (skops->op != BPF_SOCK_OPS_TCP_CONNECT_CB)
31 return 1;
32
33 sk = skops->sk;
34 if (!sk)
35 return 1;
36
37 msk = bpf_skc_to_mptcp_sock(sk);
38 if (!msk)
39 return 1;
40
41 key = msk->token;
42 cnt = bpf_map_lookup_elem(&mptcp_sf, &key);
43 if (cnt) {
44 /* A new subflow is added to an existing MPTCP connection */
45 __sync_fetch_and_add(cnt, 1);
46 mark = *cnt;
47 } else {
48 /* A new MPTCP connection is just initiated and this is its primary subflow */
49 bpf_map_update_elem(&mptcp_sf, &key, &init, BPF_ANY);
50 mark = init;
51 }
52
53 /* Set the mark of the subflow's socket based on appearance order */
54 err = bpf_setsockopt(skops, SOL_SOCKET, SO_MARK, &mark, sizeof(mark));
55 if (err < 0)
56 return 1;
57 if (mark == 2)
58 err = bpf_setsockopt(skops, SOL_TCP, TCP_CONGESTION, cc, TCP_CA_NAME_MAX);
59
60 return 1;
61 }
62
_check_getsockopt_subflow_mark(struct mptcp_sock * msk,struct bpf_sockopt * ctx)63 static int _check_getsockopt_subflow_mark(struct mptcp_sock *msk, struct bpf_sockopt *ctx)
64 {
65 struct mptcp_subflow_context *subflow;
66 int i = 0;
67
68 mptcp_for_each_subflow(msk, subflow) {
69 struct sock *ssk;
70
71 ssk = mptcp_subflow_tcp_sock(bpf_core_cast(subflow,
72 struct mptcp_subflow_context));
73
74 if (ssk->sk_mark != ++i) {
75 ctx->retval = -2;
76 break;
77 }
78 }
79
80 return 1;
81 }
82
_check_getsockopt_subflow_cc(struct mptcp_sock * msk,struct bpf_sockopt * ctx)83 static int _check_getsockopt_subflow_cc(struct mptcp_sock *msk, struct bpf_sockopt *ctx)
84 {
85 struct mptcp_subflow_context *subflow;
86
87 mptcp_for_each_subflow(msk, subflow) {
88 struct inet_connection_sock *icsk;
89 struct sock *ssk;
90
91 ssk = mptcp_subflow_tcp_sock(bpf_core_cast(subflow,
92 struct mptcp_subflow_context));
93 icsk = bpf_core_cast(ssk, struct inet_connection_sock);
94
95 if (ssk->sk_mark == 2 &&
96 __builtin_memcmp(icsk->icsk_ca_ops->name, cc, TCP_CA_NAME_MAX)) {
97 ctx->retval = -2;
98 break;
99 }
100 }
101
102 return 1;
103 }
104
105 SEC("cgroup/getsockopt")
_getsockopt_subflow(struct bpf_sockopt * ctx)106 int _getsockopt_subflow(struct bpf_sockopt *ctx)
107 {
108 struct bpf_sock *sk = ctx->sk;
109 struct mptcp_sock *msk;
110
111 if (bpf_get_current_pid_tgid() >> 32 != pid)
112 return 1;
113
114 if (!sk || sk->protocol != IPPROTO_MPTCP ||
115 (!(ctx->level == SOL_SOCKET && ctx->optname == SO_MARK) &&
116 !(ctx->level == SOL_TCP && ctx->optname == TCP_CONGESTION)))
117 return 1;
118
119 msk = bpf_core_cast(sk, struct mptcp_sock);
120 if (msk->pm.subflows != 1) {
121 ctx->retval = -1;
122 return 1;
123 }
124
125 if (ctx->optname == SO_MARK)
126 return _check_getsockopt_subflow_mark(msk, ctx);
127 return _check_getsockopt_subflow_cc(msk, ctx);
128 }
129