1f2a6ee92SPrankur Gupta // SPDX-License-Identifier: GPL-2.0
2f2a6ee92SPrankur Gupta /* Copyright (c) 2021 Facebook */
3f2a6ee92SPrankur Gupta #include <string.h>
4f2a6ee92SPrankur Gupta #include <linux/tcp.h>
5f2a6ee92SPrankur Gupta #include <netinet/in.h>
6f2a6ee92SPrankur Gupta #include <linux/bpf.h>
7f2a6ee92SPrankur Gupta #include <bpf/bpf_helpers.h>
8f2a6ee92SPrankur Gupta #include "bpf_tcp_helpers.h"
9f2a6ee92SPrankur Gupta
10f2a6ee92SPrankur Gupta char _license[] SEC("license") = "GPL";
11f2a6ee92SPrankur Gupta
12*e01b4a72SStanislav Fomichev __u32 page_size = 0;
13*e01b4a72SStanislav Fomichev
14f2a6ee92SPrankur Gupta SEC("cgroup/setsockopt")
sockopt_qos_to_cc(struct bpf_sockopt * ctx)15f2a6ee92SPrankur Gupta int sockopt_qos_to_cc(struct bpf_sockopt *ctx)
16f2a6ee92SPrankur Gupta {
17f2a6ee92SPrankur Gupta void *optval_end = ctx->optval_end;
18f2a6ee92SPrankur Gupta int *optval = ctx->optval;
19f2a6ee92SPrankur Gupta char buf[TCP_CA_NAME_MAX];
20f2a6ee92SPrankur Gupta char cc_reno[TCP_CA_NAME_MAX] = "reno";
21f2a6ee92SPrankur Gupta char cc_cubic[TCP_CA_NAME_MAX] = "cubic";
22f2a6ee92SPrankur Gupta
23f2a6ee92SPrankur Gupta if (ctx->level != SOL_IPV6 || ctx->optname != IPV6_TCLASS)
24*e01b4a72SStanislav Fomichev goto out;
25f2a6ee92SPrankur Gupta
26f2a6ee92SPrankur Gupta if (optval + 1 > optval_end)
27f2a6ee92SPrankur Gupta return 0; /* EPERM, bounds check */
28f2a6ee92SPrankur Gupta
29f2a6ee92SPrankur Gupta if (bpf_getsockopt(ctx->sk, SOL_TCP, TCP_CONGESTION, &buf, sizeof(buf)))
30f2a6ee92SPrankur Gupta return 0;
31f2a6ee92SPrankur Gupta
32f2a6ee92SPrankur Gupta if (!tcp_cc_eq(buf, cc_cubic))
33f2a6ee92SPrankur Gupta return 0;
34f2a6ee92SPrankur Gupta
35f2a6ee92SPrankur Gupta if (*optval == 0x2d) {
36f2a6ee92SPrankur Gupta if (bpf_setsockopt(ctx->sk, SOL_TCP, TCP_CONGESTION, &cc_reno,
37f2a6ee92SPrankur Gupta sizeof(cc_reno)))
38f2a6ee92SPrankur Gupta return 0;
39f2a6ee92SPrankur Gupta }
40f2a6ee92SPrankur Gupta return 1;
41*e01b4a72SStanislav Fomichev
42*e01b4a72SStanislav Fomichev out:
43*e01b4a72SStanislav Fomichev /* optval larger than PAGE_SIZE use kernel's buffer. */
44*e01b4a72SStanislav Fomichev if (ctx->optlen > page_size)
45*e01b4a72SStanislav Fomichev ctx->optlen = 0;
46*e01b4a72SStanislav Fomichev return 1;
47f2a6ee92SPrankur Gupta }
48