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 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 char cc_reno[TCP_CA_NAME_MAX] = "reno"; 19 char cc_cubic[TCP_CA_NAME_MAX] = "cubic"; 20 21 if (ctx->level != SOL_IPV6 || ctx->optname != IPV6_TCLASS) 22 return 1; 23 24 if (optval + 1 > optval_end) 25 return 0; /* EPERM, bounds check */ 26 27 if (bpf_getsockopt(ctx->sk, SOL_TCP, TCP_CONGESTION, &buf, sizeof(buf))) 28 return 0; 29 30 if (!tcp_cc_eq(buf, cc_cubic)) 31 return 0; 32 33 if (*optval == 0x2d) { 34 if (bpf_setsockopt(ctx->sk, SOL_TCP, TCP_CONGESTION, &cc_reno, 35 sizeof(cc_reno))) 36 return 0; 37 } 38 return 1; 39 } 40