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