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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved. */
#define KBUILD_MODNAME "foo"
#include <stddef.h>
#include <string.h>
#include <linux/bpf.h>
#include <linux/icmp.h>
#include <linux/in.h>
#include <linux/if_ether.h>
#include <linux/if_packet.h>
#include <linux/if_vlan.h>
#include <linux/ip.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_endian.h>
#include "xdping.h"
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, 256);
__type(key, __u32);
__type(value, struct pinginfo);
} ping_map SEC(".maps");
static __always_inline void swap_src_dst_mac(void *data)
{
unsigned short *p = data;
unsigned short dst[3];
dst[0] = p[0];
dst[1] = p[1];
dst[2] = p[2];
p[0] = p[3];
p[1] = p[4];
p[2] = p[5];
p[3] = dst[0];
p[4] = dst[1];
p[5] = dst[2];
}
static __always_inline __u16 csum_fold_helper(__wsum sum)
{
sum = (sum & 0xffff) + (sum >> 16);
return ~((sum & 0xffff) + (sum >> 16));
}
static __always_inline __u16 ipv4_csum(void *data_start, int data_size)
{
__wsum sum;
sum = bpf_csum_diff(0, 0, data_start, data_size, 0);
return csum_fold_helper(sum);
}
#define ICMP_ECHO_LEN 64
static __always_inline int icmp_check(struct xdp_md *ctx, int type)
{
void *data_end = (void *)(long)ctx->data_end;
void *data = (void *)(long)ctx->data;
struct ethhdr *eth = data;
struct icmphdr *icmph;
struct iphdr *iph;
if (data + sizeof(*eth) + sizeof(*iph) + ICMP_ECHO_LEN > data_end)
return XDP_PASS;
if (eth->h_proto != bpf_htons(ETH_P_IP))
return XDP_PASS;
iph = data + sizeof(*eth);
if (iph->protocol != IPPROTO_ICMP)
return XDP_PASS;
if (bpf_ntohs(iph->tot_len) - sizeof(*iph) != ICMP_ECHO_LEN)
return XDP_PASS;
icmph = data + sizeof(*eth) + sizeof(*iph);
if (icmph->type != type)
return XDP_PASS;
return XDP_TX;
}
SEC("xdp")
int xdping_client(struct xdp_md *ctx)
{
void *data_end = (void *)(long)ctx->data_end;
void *data = (void *)(long)ctx->data;
struct pinginfo *pinginfo = NULL;
struct ethhdr *eth = data;
struct icmphdr *icmph;
struct iphdr *iph;
__u64 recvtime;
__be32 raddr;
__be16 seq;
int ret;
__u8 i;
ret = icmp_check(ctx, ICMP_ECHOREPLY);
if (ret != XDP_TX)
return ret;
iph = data + sizeof(*eth);
icmph = data + sizeof(*eth) + sizeof(*iph);
raddr = iph->saddr;
/* Record time reply received. */
recvtime = bpf_ktime_get_ns();
pinginfo = bpf_map_lookup_elem(&ping_map, &raddr);
if (!pinginfo || pinginfo->seq != icmph->un.echo.sequence)
return XDP_PASS;
if (pinginfo->start) {
#pragma clang loop unroll(full)
for (i = 0; i < XDPING_MAX_COUNT; i++) {
if (pinginfo->times[i] == 0)
break;
}
/* verifier is fussy here... */
if (i < XDPING_MAX_COUNT) {
pinginfo->times[i] = recvtime -
pinginfo->start;
pinginfo->start = 0;
i++;
}
/* No more space for values? */
if (i == pinginfo->count || i == XDPING_MAX_COUNT)
return XDP_PASS;
}
/* Now convert reply back into echo request. */
swap_src_dst_mac(data);
iph->saddr = iph->daddr;
iph->daddr = raddr;
icmph->type = ICMP_ECHO;
seq = bpf_htons(bpf_ntohs(icmph->un.echo.sequence) + 1);
icmph->un.echo.sequence = seq;
icmph->checksum = 0;
icmph->checksum = ipv4_csum(icmph, ICMP_ECHO_LEN);
pinginfo->seq = seq;
pinginfo->start = bpf_ktime_get_ns();
return XDP_TX;
}
SEC("xdp")
int xdping_server(struct xdp_md *ctx)
{
void *data_end = (void *)(long)ctx->data_end;
void *data = (void *)(long)ctx->data;
struct ethhdr *eth = data;
struct icmphdr *icmph;
struct iphdr *iph;
__be32 raddr;
int ret;
ret = icmp_check(ctx, ICMP_ECHO);
if (ret != XDP_TX)
return ret;
iph = data + sizeof(*eth);
icmph = data + sizeof(*eth) + sizeof(*iph);
raddr = iph->saddr;
/* Now convert request into echo reply. */
swap_src_dst_mac(data);
iph->saddr = iph->daddr;
iph->daddr = raddr;
icmph->type = ICMP_ECHOREPLY;
icmph->checksum = 0;
icmph->checksum = ipv4_csum(icmph, ICMP_ECHO_LEN);
return XDP_TX;
}
char _license[] SEC("license") = "GPL";
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