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