diff options
| author | Lawrence Brakmo <brakmo@fb.com> | 2017-10-20 21:05:42 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-10-22 05:12:05 +0300 |
| commit | c890063e440456e75c2e70f6bcec3797f1771eb6 (patch) | |
| tree | 81e2bf2415e67f9d54a668aa0b5e775c0981a53d /samples/bpf/tcp_basertt_kern.c | |
| parent | 85cce215781685bbc94b6af2bd1aa40b71965a70 (diff) | |
| download | linux-c890063e440456e75c2e70f6bcec3797f1771eb6.tar.xz | |
bpf: sample BPF_SOCKET_OPS_BASE_RTT program
Sample socket_ops BPF program to test the BPF helper function
bpf_getsocketops and the new socket_ops op BPF_SOCKET_OPS_BASE_RTT.
The program provides a base RTT of 80us when the calling flow is
within a DC (as determined by the IPV6 prefix) and the congestion
algorithm is "nv".
Signed-off-by: Lawrence Brakmo <brakmo@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked_by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'samples/bpf/tcp_basertt_kern.c')
| -rw-r--r-- | samples/bpf/tcp_basertt_kern.c | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/samples/bpf/tcp_basertt_kern.c b/samples/bpf/tcp_basertt_kern.c new file mode 100644 index 000000000000..4bf4fc597db9 --- /dev/null +++ b/samples/bpf/tcp_basertt_kern.c @@ -0,0 +1,78 @@ +/* Copyright (c) 2017 Facebook + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + * + * BPF program to set base_rtt to 80us when host is running TCP-NV and + * both hosts are in the same datacenter (as determined by IPv6 prefix). + * + * Use load_sock_ops to load this BPF program. + */ + +#include <uapi/linux/bpf.h> +#include <uapi/linux/tcp.h> +#include <uapi/linux/if_ether.h> +#include <uapi/linux/if_packet.h> +#include <uapi/linux/ip.h> +#include <linux/socket.h> +#include "bpf_helpers.h" +#include "bpf_endian.h" + +#define DEBUG 1 + +#define bpf_printk(fmt, ...) \ +({ \ + char ____fmt[] = fmt; \ + bpf_trace_printk(____fmt, sizeof(____fmt), \ + ##__VA_ARGS__); \ +}) + +SEC("sockops") +int bpf_basertt(struct bpf_sock_ops *skops) +{ + char cong[20]; + char nv[] = "nv"; + int rv = 0, n; + int op; + + op = (int) skops->op; + +#ifdef DEBUG + bpf_printk("BPF command: %d\n", op); +#endif + + /* Check if both hosts are in the same datacenter. For this + * example they are if the 1st 5.5 bytes in the IPv6 address + * are the same. + */ + if (skops->family == AF_INET6 && + skops->local_ip6[0] == skops->remote_ip6[0] && + (bpf_ntohl(skops->local_ip6[1]) & 0xfff00000) == + (bpf_ntohl(skops->remote_ip6[1]) & 0xfff00000)) { + switch (op) { + case BPF_SOCK_OPS_BASE_RTT: + n = bpf_getsockopt(skops, SOL_TCP, TCP_CONGESTION, + cong, sizeof(cong)); + if (!n && !__builtin_memcmp(cong, nv, sizeof(nv)+1)) { + /* Set base_rtt to 80us */ + rv = 80; + } else if (n) { + rv = n; + } else { + rv = -1; + } + break; + default: + rv = -1; + } + } else { + rv = -1; + } +#ifdef DEBUG + bpf_printk("Returning %d\n", rv); +#endif + skops->reply = rv; + return 1; +} +char _license[] SEC("license") = "GPL"; |