1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* Copyright (c) 2021 Facebook */ |
3 | #include <string.h> |
4 | #include <linux/tcp.h> |
5 | #include <netinet/in.h> |
6 | #include <linux/bpf.h> |
7 | #include <bpf/bpf_helpers.h> |
8 | #include "bpf_tcp_helpers.h" |
9 | |
10 | char _license[] SEC("license" ) = "GPL" ; |
11 | |
12 | __s32 page_size = 0; |
13 | |
14 | SEC("cgroup/setsockopt" ) |
15 | int sockopt_qos_to_cc(struct bpf_sockopt *ctx) |
16 | { |
17 | void *optval_end = ctx->optval_end; |
18 | int *optval = ctx->optval; |
19 | char buf[TCP_CA_NAME_MAX]; |
20 | char cc_reno[TCP_CA_NAME_MAX] = "reno" ; |
21 | char cc_cubic[TCP_CA_NAME_MAX] = "cubic" ; |
22 | |
23 | if (ctx->level != SOL_IPV6 || ctx->optname != IPV6_TCLASS) |
24 | goto out; |
25 | |
26 | if (optval + 1 > optval_end) |
27 | return 0; /* EPERM, bounds check */ |
28 | |
29 | if (bpf_getsockopt(ctx->sk, SOL_TCP, TCP_CONGESTION, &buf, sizeof(buf))) |
30 | return 0; |
31 | |
32 | if (!tcp_cc_eq(buf, cc_cubic)) |
33 | return 0; |
34 | |
35 | if (*optval == 0x2d) { |
36 | if (bpf_setsockopt(ctx->sk, SOL_TCP, TCP_CONGESTION, &cc_reno, |
37 | sizeof(cc_reno))) |
38 | return 0; |
39 | } |
40 | return 1; |
41 | |
42 | out: |
43 | /* optval larger than PAGE_SIZE use kernel's buffer. */ |
44 | if (ctx->optlen > page_size) |
45 | ctx->optlen = 0; |
46 | return 1; |
47 | } |
48 | |