root/tools/testing/selftests/bpf/progs/xdping_kern.c

DEFINITIONS

1. swap_src_dst_mac
2. csum_fold_helper
3. ipv4_csum
4. icmp_check
5. SEC
6. SEC

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved. */
   3 
   4 #define KBUILD_MODNAME "foo"
   5 #include <stddef.h>
   6 #include <string.h>
   7 #include <linux/bpf.h>
   8 #include <linux/icmp.h>
   9 #include <linux/in.h>
  10 #include <linux/if_ether.h>
  11 #include <linux/if_packet.h>
  12 #include <linux/if_vlan.h>
  13 #include <linux/ip.h>
  14 
  15 #include "bpf_helpers.h"
  16 #include "bpf_endian.h"
  17 
  18 #include "xdping.h"
  19 
  20 struct {
  21         __uint(type, BPF_MAP_TYPE_HASH);
  22         __uint(max_entries, 256);
  23         __type(key, __u32);
  24         __type(value, struct pinginfo);
  25 } ping_map SEC(".maps");
  26 
  27 static __always_inline void swap_src_dst_mac(void *data)
  28 {
  29         unsigned short *p = data;
  30         unsigned short dst[3];
  31 
  32         dst[0] = p[0];
  33         dst[1] = p[1];
  34         dst[2] = p[2];
  35         p[0] = p[3];
  36         p[1] = p[4];
  37         p[2] = p[5];
  38         p[3] = dst[0];
  39         p[4] = dst[1];
  40         p[5] = dst[2];
  41 }
  42 
  43 static __always_inline __u16 csum_fold_helper(__wsum sum)
  44 {
  45         sum = (sum & 0xffff) + (sum >> 16);
  46         return ~((sum & 0xffff) + (sum >> 16));
  47 }
  48 
  49 static __always_inline __u16 ipv4_csum(void *data_start, int data_size)
  50 {
  51         __wsum sum;
  52 
  53         sum = bpf_csum_diff(0, 0, data_start, data_size, 0);
  54         return csum_fold_helper(sum);
  55 }
  56 
  57 #define ICMP_ECHO_LEN           64
  58 
  59 static __always_inline int icmp_check(struct xdp_md *ctx, int type)
  60 {
  61         void *data_end = (void *)(long)ctx->data_end;
  62         void *data = (void *)(long)ctx->data;
  63         struct ethhdr *eth = data;
  64         struct icmphdr *icmph;
  65         struct iphdr *iph;
  66 
  67         if (data + sizeof(*eth) + sizeof(*iph) + ICMP_ECHO_LEN > data_end)
  68                 return XDP_PASS;
  69 
  70         if (eth->h_proto != bpf_htons(ETH_P_IP))
  71                 return XDP_PASS;
  72 
  73         iph = data + sizeof(*eth);
  74 
  75         if (iph->protocol != IPPROTO_ICMP)
  76                 return XDP_PASS;
  77 
  78         if (bpf_ntohs(iph->tot_len) - sizeof(*iph) != ICMP_ECHO_LEN)
  79                 return XDP_PASS;
  80 
  81         icmph = data + sizeof(*eth) + sizeof(*iph);
  82 
  83         if (icmph->type != type)
  84                 return XDP_PASS;
  85 
  86         return XDP_TX;
  87 }
  88 
  89 SEC("xdpclient")
  90 int xdping_client(struct xdp_md *ctx)
  91 {
  92         void *data_end = (void *)(long)ctx->data_end;
  93         void *data = (void *)(long)ctx->data;
  94         struct pinginfo *pinginfo = NULL;
  95         struct ethhdr *eth = data;
  96         struct icmphdr *icmph;
  97         struct iphdr *iph;
  98         __u64 recvtime;
  99         __be32 raddr;
 100         __be16 seq;
 101         int ret;
 102         __u8 i;
 103 
 104         ret = icmp_check(ctx, ICMP_ECHOREPLY);
 105 
 106         if (ret != XDP_TX)
 107                 return ret;
 108 
 109         iph = data + sizeof(*eth);
 110         icmph = data + sizeof(*eth) + sizeof(*iph);
 111         raddr = iph->saddr;
 112 
 113         /* Record time reply received. */
 114         recvtime = bpf_ktime_get_ns();
 115         pinginfo = bpf_map_lookup_elem(&ping_map, &raddr);
 116         if (!pinginfo || pinginfo->seq != icmph->un.echo.sequence)
 117                 return XDP_PASS;
 118 
 119         if (pinginfo->start) {
 120 #pragma clang loop unroll(full)
 121                 for (i = 0; i < XDPING_MAX_COUNT; i++) {
 122                         if (pinginfo->times[i] == 0)
 123                                 break;
 124                 }
 125                 /* verifier is fussy here... */
 126                 if (i < XDPING_MAX_COUNT) {
 127                         pinginfo->times[i] = recvtime -
 128                                              pinginfo->start;
 129                         pinginfo->start = 0;
 130                         i++;
 131                 }
 132                 /* No more space for values? */
 133                 if (i == pinginfo->count || i == XDPING_MAX_COUNT)
 134                         return XDP_PASS;
 135         }
 136 
 137         /* Now convert reply back into echo request. */
 138         swap_src_dst_mac(data);
 139         iph->saddr = iph->daddr;
 140         iph->daddr = raddr;
 141         icmph->type = ICMP_ECHO;
 142         seq = bpf_htons(bpf_ntohs(icmph->un.echo.sequence) + 1);
 143         icmph->un.echo.sequence = seq;
 144         icmph->checksum = 0;
 145         icmph->checksum = ipv4_csum(icmph, ICMP_ECHO_LEN);
 146 
 147         pinginfo->seq = seq;
 148         pinginfo->start = bpf_ktime_get_ns();
 149 
 150         return XDP_TX;
 151 }
 152 
 153 SEC("xdpserver")
 154 int xdping_server(struct xdp_md *ctx)
 155 {
 156         void *data_end = (void *)(long)ctx->data_end;
 157         void *data = (void *)(long)ctx->data;
 158         struct ethhdr *eth = data;
 159         struct icmphdr *icmph;
 160         struct iphdr *iph;
 161         __be32 raddr;
 162         int ret;
 163 
 164         ret = icmp_check(ctx, ICMP_ECHO);
 165 
 166         if (ret != XDP_TX)
 167                 return ret;
 168 
 169         iph = data + sizeof(*eth);
 170         icmph = data + sizeof(*eth) + sizeof(*iph);
 171         raddr = iph->saddr;
 172 
 173         /* Now convert request into echo reply. */
 174         swap_src_dst_mac(data);
 175         iph->saddr = iph->daddr;
 176         iph->daddr = raddr;
 177         icmph->type = ICMP_ECHOREPLY;
 178         icmph->checksum = 0;
 179         icmph->checksum = ipv4_csum(icmph, ICMP_ECHO_LEN);
 180 
 181         return XDP_TX;
 182 }
 183 
 184 char _license[] SEC("license") = "GPL";