diff options
| -rw-r--r-- | samples/bpf/Makefile | 1 | ||||
| -rw-r--r-- | samples/bpf/tcp_rwnd_kern.c | 69 |
2 files changed, 70 insertions, 0 deletions
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index e29370a19957..ca955280cbeb 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -114,6 +114,7 @@ always += xdp_tx_iptunnel_kern.o always += test_map_in_map_kern.o always += cookie_uid_helper_example.o always += tcp_synrto_kern.o +always += tcp_rwnd_kern.o HOSTCFLAGS += -I$(objtree)/usr/include HOSTCFLAGS += -I$(srctree)/tools/lib/ diff --git a/samples/bpf/tcp_rwnd_kern.c b/samples/bpf/tcp_rwnd_kern.c new file mode 100644 index 000000000000..3f2a228f81ce --- /dev/null +++ b/samples/bpf/tcp_rwnd_kern.c @@ -0,0 +1,69 @@ +/* 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 initial receive window to 40 packets when using IPv6 + * and the first 5.5 bytes of the IPv6 addresses are not the same (in this + * example that means both hosts are not the same datacenter). + * + * Use load_sock_ops to load this BPF program. + */ + +#include <uapi/linux/bpf.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_rwnd(struct bpf_sock_ops *skops) +{ + int rv = -1; + int op; + + /* For testing purposes, only execute rest of BPF program + * if neither port numberis 55601 + */ + if (bpf_ntohl(skops->remote_port) != + 55601 && skops->local_port != 55601) + return -1; + + op = (int) skops->op; + +#ifdef DEBUG + bpf_printk("BPF command: %d\n", op); +#endif + + /* Check for RWND_INIT operation and IPv6 addresses */ + if (op == BPF_SOCK_OPS_RWND_INIT && + skops->family == AF_INET6) { + + /* If the first 5.5 bytes of the IPv6 address are not the same + * then both hosts are not in the same datacenter + * so use a larger initial advertized window (40 packets) + */ + if (skops->local_ip6[0] != skops->remote_ip6[0] || + (bpf_ntohl(skops->local_ip6[1]) & 0xfffff000) != + (bpf_ntohl(skops->remote_ip6[1]) & 0xfffff000)) + rv = 40; + } +#ifdef DEBUG + bpf_printk("Returning %d\n", rv); +#endif + skops->reply = rv; + return 1; +} +char _license[] SEC("license") = "GPL"; |