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 #include "str.h"
  21
  22 static const char *short_options = "vhi:Vdbf:pD:";
  23 static const struct option long_options[] = {
  24         {"input",       required_argument,      NULL, 'i'},
  25         {"format",      required_argument,      NULL, 'f'},
  26         {"cpp",         no_argument,            NULL, 'p'},
  27         {"define",      required_argument,      NULL, 'D'},
  28         {"verbose",     no_argument,            NULL, 'V'},
  29         {"bypass",      no_argument,            NULL, 'b'},
  30         {"dump",        no_argument,            NULL, 'd'},
  31         {"version",     no_argument,            NULL, 'v'},
  32         {"help",        no_argument,            NULL, 'h'},
  33         {NULL, 0, NULL, 0}
  34 };
  35
  36 static const char *copyright =
  37         "Please report bugs at https://github.com/netsniff-ng/netsniff-ng/issues\n"
  38         "Copyright (C) 2011-2013 Daniel Borkmann <dborkma@tik.ee.ethz.ch>,\n"
  39         "Swiss federal institute of technology (ETH Zurich)\n"
  40         "License: GNU GPL version 2.0\n"
  41         "This is free software: you are free to change and redistribute it.\n"
  42         "There is NO WARRANTY, to the extent permitted by law.";
  43
  44 extern int compile_filter(char *file, bool verbose, int bypass, int format,
  45                           bool invoke_cpp, char **cpp_argv);
  46
  47 static void __noreturn help(void)
  48 {
  49         printf("bpfc %s, a tiny BPF compiler\n", VERSION_STRING);
  50         puts("http://www.netsniff-ng.org\n\n"
  51              "Usage: bpfc [options] || bpfc <program>\n"
  52              "Options:\n"
  53              "  -i|--input <program/->  Berkeley Packet Filter file/stdin\n"
  54              "  -p|--cpp                Run bpf program through C preprocessor\n"
  55              "  -D|--define             Add macro/define for C preprocessor\n"
  56              "  -f|--format <format>    Output format: C|netsniff-ng|xt_bpf|tcpdump\n"
  57              "  -b|--bypass             Bypass filter validation (e.g. for bug testing)\n"
  58              "  -V|--verbose            Be more verbose\n"
  59              "  -d|--dump               Dump supported instruction table\n"
  60              "  -v|--version            Print version and exit\n"
  61              "  -h|--help               Print this help and exit\n\n"
  62              "Examples:\n"
  63              "  bpfc fubar\n"
  64              "  bpfc fubar > foo (bpfc -f C -i fubar > foo) -->  netsniff-ng -f foo ...\n"
  65              "  bpfc -f tcpdump -i fubar > foo -->  tcpdump -ddd like ...\n"
  66              "  bpfc -f xt_bpf -b -p -i fubar\n"
  67              "  iptables -A INPUT -m bpf --bytecode \"`./bpfc -f xt_bpf -i fubar`\" -j LOG\n"
  68              "  bpfc -   (read from stdin)\n"
  69              "Note:\n"
  70              "  Generation of seccomp-BPF filters are fully supported as well.\n");
  71         puts(copyright);
  72         die();
  73 }
  74
  75 static void __noreturn version(void)
  76 {
  77         printf("bpfc %s, Git id: %s\n", VERSION_LONG, GITVERSION);
  78         puts("a tiny BPF compiler\n"
  79              "http://www.netsniff-ng.org\n");
  80         puts(copyright);
  81         die();
  82 }
  83
  84 int main(int argc, char **argv)
  85 {
  86         int ret, c, bypass = 0, format = 0;
  87         bool verbose = false, invoke_cpp = false;
  88         char **cpp_argv = NULL;
  89         size_t cpp_argc = 0;
  90         char *file = NULL;
  91
  92         setfsuid(getuid());
  93         setfsgid(getgid());
  94
  95         if (argc == 1)
  96                 help();
  97
  98         while ((c = getopt_long(argc, argv, short_options, long_options,
  99                                 NULL)) != EOF) {
 100                 switch (c) {
 101                 case 'h':
 102                         help();
 103                         break;
 104                 case 'v':
 105                         version();
 106                         break;
 107                 case 'V':
 108                         verbose = true;
 109                         break;
 110                 case 'p':
 111                         invoke_cpp = true;
 112                         break;
 113                 case 'D':
 114                         cpp_argv = argv_insert(cpp_argv, &cpp_argc, "-D");
 115                         cpp_argv = argv_insert(cpp_argv, &cpp_argc, optarg);
 116                         break;
 117                 case 'f':
 118                         if (!strncmp(optarg, "C", 1) ||
 119                             !strncmp(optarg, "netsniff-ng", 11))
 120                                 format = 0;
 121                         else if (!strncmp(optarg, "tcpdump", 7))
 122                                 format = 2;
 123                         else if (!strncmp(optarg, "xt_bpf", 6) ||
 124                                  !strncmp(optarg, "tc", 2))
 125                                 format = 1;
 126                         else
 127                                 help();
 128                         break;
 129                 case 'b':
 130                         bypass = 1;
 131                         break;
 132                 case 'd':
 133                         bpf_dump_op_table();
 134                         die();
 135                 case 'i':
 136                         file = xstrdup(optarg);
 137                         break;
 138                 case '?':
 139                         switch (optopt) {
 140                         case 'i':
 141                         case 'f':
 142                                 panic("Option -%c requires an argument!\n",
 143                                       optopt);
 144                         default:
 145                                 if (isprint(optopt))
 146                                         printf("Unknown option character `0x%X\'!\n", optopt);
 147                                 die();
 148                         }
 149                 default:
 150                         break;
 151                 }
 152         }
 153
 154         if (argc == 2)
 155                 file = xstrdup(argv[1]);
 156         if (!file)
 157                 panic("No Berkeley Packet Filter program specified!\n");
 158
 159         ret = compile_filter(file, verbose, bypass, format, invoke_cpp, cpp_argv);
 160
 161         argv_free(cpp_argv);
 162         xfree(file);
 163         return ret;
 164 }