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1// SPDX-License-Identifier: GPL-2.02/* Copyright (c) 2021 Facebook */3#include "bpf_tracing_net.h"4 5char _license[] SEC("license") = "GPL";6 7__s32 page_size = 0;8 9const char cc_reno[TCP_CA_NAME_MAX] = "reno";10const char cc_cubic[TCP_CA_NAME_MAX] = "cubic";11 12SEC("cgroup/setsockopt")13int 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 38out: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