1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2021 Facebook */
3 #include "bpf_tracing_net.h"
4
5 char _license[] SEC("license") = "GPL";
6
7 __s32 page_size = 0;
8
9 const char cc_reno[TCP_CA_NAME_MAX] = "reno";
10 const char cc_cubic[TCP_CA_NAME_MAX] = "cubic";
11
12 SEC("cgroup/setsockopt")
13 int sockopt_qos_to_cc(struct bpf_sockopt *ctx)
14 {
15 void *optval_end = ctx->optval_end;
16 int *optval = ctx->optval;
17 char buf[TCP_CA_NAME_MAX];
18
19 if (ctx->level != SOL_IPV6 || ctx->optname != IPV6_TCLASS)
20 goto out;
21
22 if (optval + 1 > optval_end)
23 return 0; /* EPERM, bounds check */
24
25 if (bpf_getsockopt(ctx->sk, SOL_TCP, TCP_CONGESTION, &buf, sizeof(buf)))
26 return 0;
27
28 if (bpf_strncmp(buf, sizeof(buf), cc_cubic))
29 return 0;
30
31 if (*optval == 0x2d) {
32 if (bpf_setsockopt(ctx->sk, SOL_TCP, TCP_CONGESTION, (void *)&cc_reno,
33 sizeof(cc_reno)))
34 return 0;
35 }
36 return 1;
37
38 out:
39 /* optval larger than PAGE_SIZE use kernel's buffer. */
40 if (ctx->optlen > page_size)
41 ctx->optlen = 0;
42 return 1;
43 }
44
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