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