ceph/src/seastar/dpdk/examples/bpf/t1.c

   1 /* SPDX-License-Identifier: BSD-3-Clause
   2  * Copyright(c) 2018 Intel Corporation
   3  */
   4
   5 /*
   6  * eBPF program sample.
   7  * Accepts pointer to first segment packet data as an input parameter.
   8  * analog of tcpdump -s 1 -d 'dst 1.2.3.4 && udp && dst port 5000'
   9  * (000) ldh      [12]
  10  * (001) jeq      #0x800           jt 2    jf 12
  11  * (002) ld       [30]
  12  * (003) jeq      #0x1020304       jt 4    jf 12
  13  * (004) ldb      [23]
  14  * (005) jeq      #0x11            jt 6    jf 12
  15  * (006) ldh      [20]
  16  * (007) jset     #0x1fff          jt 12   jf 8
  17  * (008) ldxb     4*([14]&0xf)
  18  * (009) ldh      [x + 16]
  19  * (010) jeq      #0x1388          jt 11   jf 12
  20  * (011) ret      #1
  21  * (012) ret      #0
  22  *
  23  * To compile on x86:
  24  * clang -O2 -U __GNUC__ -target bpf -c t1.c
  25  *
  26  * To compile on ARM:
  27  * clang -O2 -I/usr/include/aarch64-linux-gnu/ -target bpf -c t1.c
  28  */
  29
  30 #include <stdint.h>
  31 #include <net/ethernet.h>
  32 #include <netinet/ip.h>
  33 #include <netinet/udp.h>
  34 #include <arpa/inet.h>
  35
  36 uint64_t
  37 entry(void *pkt)
  38 {
  39         struct ether_header *ether_header = (void *)pkt;
  40
  41         if (ether_header->ether_type != htons(0x0800))
  42                 return 0;
  43
  44         struct iphdr *iphdr = (void *)(ether_header + 1);
  45         if (iphdr->protocol != 17 || (iphdr->frag_off & 0x1ffff) != 0 ||
  46                         iphdr->daddr != htonl(0x1020304))
  47                 return 0;
  48
  49         int hlen = iphdr->ihl * 4;
  50         struct udphdr *udphdr = (void *)iphdr + hlen;
  51
  52         if (udphdr->dest != htons(5000))
  53                 return 0;
  54
  55         return 1;
  56 }