bpfc.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * Copyright 2011 Daniel Borkmann <dborkma@tik.ee.ethz.ch>,
   4  * Swiss federal institute of technology (ETH Zurich)
   5  * Subject to the GPL, version 2.
   6  */
   7
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <stdbool.h>
  11 #include <getopt.h>
  12 #include <ctype.h>
  13 #include <unistd.h>
  14 #include <sys/fsuid.h>
  15
  16 #include "xmalloc.h"
  17 #include "die.h"
  18 #include "bpf.h"
  19 #include "config.h"
  20
  21 static const char *short_options = "vhi:Vdbf:p";
  22 static const struct option long_options[] = {
  23         {"input",       required_argument,      NULL, 'i'},
  24         {"format",      required_argument,      NULL, 'f'},
  25         {"cpp",         no_argument,            NULL, 'p'},
  26         {"verbose",     no_argument,            NULL, 'V'},
  27         {"bypass",      no_argument,            NULL, 'b'},
  28         {"dump",        no_argument,            NULL, 'd'},
  29         {"version",     no_argument,            NULL, 'v'},
  30         {"help",        no_argument,            NULL, 'h'},
  31         {NULL, 0, NULL, 0}
  32 };
  33
  34 static const char *copyright = "Please report bugs to <netsniff-ng@googlegroups.com>\n"
  35         "Copyright (C) 2011-2013 Daniel Borkmann <dborkma@tik.ee.ethz.ch>,\n"
  36         "Swiss federal institute of technology (ETH Zurich)\n"
  37         "License: GNU GPL version 2.0\n"
  38         "This is free software: you are free to change and redistribute it.\n"
  39         "There is NO WARRANTY, to the extent permitted by law.";
  40
  41 extern int compile_filter(char *file, int verbose, int bypass, int format,
  42                           bool invoke_cpp);
  43
  44 static void __noreturn help(void)
  45 {
  46         printf("bpfc %s, a tiny BPF compiler\n", VERSION_STRING);
  47         puts("http://www.netsniff-ng.org\n\n"
  48              "Usage: bpfc [options] || bpfc <program>\n"
  49              "Options:\n"
  50              "  -i|--input <program/->  Berkeley Packet Filter file/stdin\n"
  51              "  -p|--cpp                Run bpf program through C preprocessor\n"
  52              "  -f|--format <format>    Output format: C|netsniff-ng|xt_bpf|tcpdump\n"
  53              "  -b|--bypass             Bypass filter validation (e.g. for bug testing)\n"
  54              "  -V|--verbose            Be more verbose\n"
  55              "  -d|--dump               Dump supported instruction table\n"
  56              "  -v|--version            Print version and exit\n"
  57              "  -h|--help               Print this help and exit\n\n"
  58              "Examples:\n"
  59              "  bpfc fubar\n"
  60              "  bpfc fubar > foo (bpfc -f C -i fubar > foo) -->  netsniff-ng -f foo ...\n"
  61              "  bpfc -f tcpdump -i fubar > foo -->  tcpdump -ddd like ...\n"
  62              "  bpfc -f xt_bpf -b -p -i fubar\n"
  63              "  iptables -A INPUT -m bpf --bytecode \"`./bpfc -f xt_bpf -i fubar`\" -j LOG\n"
  64              "  bpfc -   (read from stdin)\n"
  65              "Note:\n"
  66              "  Generation of seccomp-BPF filters are fully supported as well.\n");
  67         puts(copyright);
  68         die();
  69 }
  70
  71 static void __noreturn version(void)
  72 {
  73         printf("bpfc %s, Git id: %s\n", VERSION_LONG, GITVERSION);
  74         puts("a tiny BPF compiler\n"
  75              "http://www.netsniff-ng.org\n");
  76         puts(copyright);
  77         die();
  78 }
  79
  80 int main(int argc, char **argv)
  81 {
  82         int ret, verbose = 0, c, opt_index, bypass = 0, format = 0;
  83         bool invoke_cpp = false;
  84         char *file = NULL;
  85
  86         setfsuid(getuid());
  87         setfsgid(getgid());
  88
  89         if (argc == 1)
  90                 help();
  91
  92         while ((c = getopt_long(argc, argv, short_options,
  93                                 long_options, &opt_index)) != EOF) {
  94                 switch (c) {
  95                 case 'h':
  96                         help();
  97                         break;
  98                 case 'v':
  99                         version();
 100                         break;
 101                 case 'V':
 102                         verbose = 1;
 103                         break;
 104                 case 'p':
 105                         invoke_cpp = true;
 106                         break;
 107                 case 'f':
 108                         if (!strncmp(optarg, "C", 1) ||
 109                             !strncmp(optarg, "netsniff-ng", 11))
 110                                 format = 0;
 111                         else if (!strncmp(optarg, "tcpdump", 7))
 112                                 format = 2;
 113                         else if (!strncmp(optarg, "xt_bpf", 6) ||
 114                                  !strncmp(optarg, "tc", 2))
 115                                 format = 1;
 116                         else
 117                                 help();
 118                         break;
 119                 case 'b':
 120                         bypass = 1;
 121                         break;
 122                 case 'd':
 123                         bpf_dump_op_table();
 124                         die();
 125                 case 'i':
 126                         file = xstrdup(optarg);
 127                         break;
 128                 case '?':
 129                         switch (optopt) {
 130                         case 'i':
 131                         case 'f':
 132                                 panic("Option -%c requires an argument!\n",
 133                                       optopt);
 134                         default:
 135                                 if (isprint(optopt))
 136                                         printf("Unknown option character `0x%X\'!\n", optopt);
 137                                 die();
 138                         }
 139                 default:
 140                         break;
 141                 }
 142         }
 143
 144         if (argc == 2)
 145                 file = xstrdup(argv[1]);
 146         if (!file)
 147                 panic("No Berkeley Packet Filter program specified!\n");
 148
 149         ret = compile_filter(file, verbose, bypass, format, invoke_cpp);
 150
 151         xfree(file);
 152         return ret;
 153 }