rngd.c

   1 /*
   2  * rngd.c -- Random Number Generator daemon
   3  *
   4  * rngd reads data from a hardware random number generator, verifies it
   5  * looks like random data, and adds it to /dev/random's entropy store.
   6  *
   7  * In theory, this should allow you to read very quickly from
   8  * /dev/random; rngd also adds bytes to the entropy store periodically
   9  * when it's full, which makes predicting the entropy store's contents
  10  * harder.
  11  *
  12  * Copyright (C) 2001 Philipp Rumpf
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with this program; if not, write to the Free Software
  26  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  27  */
  28
  29 #define _GNU_SOURCE
  30
  31 #ifndef HAVE_CONFIG_H
  32 #error Invalid or missing autoconf build environment
  33 #endif
  34
  35 #include "rng-tools-config.h"
  36
  37 #include <unistd.h>
  38 #include <stdint.h>
  39 #include <stdio.h>
  40 #include <stdlib.h>
  41 #include <sys/types.h>
  42 #include <sys/stat.h>
  43 #include <fcntl.h>
  44 #include <errno.h>
  45 #include <string.h>
  46 #include <argp.h>
  47 #include <syslog.h>
  48
  49 #include "rngd.h"
  50 #include "fips.h"
  51 #include "exits.h"
  52 #include "rngd_entsource.h"
  53 #include "rngd_linux.h"
  54
  55 /*
  56  * Globals
  57  */
  58
  59 /* Background/daemon mode */
  60 int am_daemon;                          /* Nonzero if we went daemon */
  61
  62 /* Command line arguments and processing */
  63 const char *argp_program_version =
  64         "rngd " VERSION "\n"
  65         "Copyright 2001-2004 Jeff Garzik\n"
  66         "Copyright (c) 2001 by Philipp Rumpf\n"
  67         "This is free software; see the source for copying conditions.  There is NO "
  68         "warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.";
  69
  70 const char *argp_program_bug_address = PACKAGE_BUGREPORT;
  71
  72 static char doc[] =
  73         "Check and feed random data from hardware device to kernel entropy pool.\n";
  74
  75 static struct argp_option options[] = {
  76         { "foreground", 'f', 0, 0, "Do not fork and become a daemon" },
  77
  78         { "background", 'b', 0, 0, "Become a daemon (default)" },
  79
  80         { "random-device", 'o', "file", 0,
  81           "Kernel device used for random number output (default: /dev/random)" },
  82
  83         { "rng-device", 'r', "file", 0,
  84           "Kernel device used for random number input (default: /dev/hwrandom)" },
  85
  86         { "random-step", 's', "nnn", 0,
  87           "Number of bytes written to random-device at a time (default: 64)" },
  88
  89         { "fill-watermark", 'W', "n", 0,
  90           "Do not stop feeding entropy to random-device until at least n bits of entropy are available in the pool (default: 2048), 0 <= n <= 4096" },
  91
  92         { "timeout", 't', "nnn", 0,
  93           "Interval written to random-device when the entropy pool is full, in seconds (default: 60)" },
  94
  95         { 0 },
  96 };
  97
  98 static struct arguments default_arguments = {
  99         .rng_name       = "/dev/hwrandom",
 100         .random_name    = "/dev/random",
 101         .poll_timeout   = 60,
 102         .random_step    = 64,
 103         .fill_watermark = 2048,
 104         .daemon         = 1,
 105 };
 106 struct arguments *arguments = &default_arguments;
 107
 108
 109 /*
 110  * command line processing
 111  */
 112 static error_t parse_opt (int key, char *arg, struct argp_state *state)
 113 {
 114         struct arguments *arguments = state->input;
 115
 116         switch(key) {
 117         case 'o':
 118                 arguments->random_name = arg;
 119                 break;
 120         case 'r':
 121                 arguments->rng_name = arg;
 122                 break;
 123         case 't': {
 124                 float f;
 125                 if (sscanf(arg, "%f", &f) == 0)
 126                         argp_usage(state);
 127                 else
 128                         arguments->poll_timeout = f;
 129                 break;
 130         }
 131
 132         case 'f':
 133                 arguments->daemon = 0;
 134                 break;
 135         case 'b':
 136                 arguments->daemon = 1;
 137                 break;
 138         case 's':
 139                 if (sscanf(arg, "%i", &arguments->random_step) == 0)
 140                         argp_usage(state);
 141                 break;
 142         case 'W': {
 143                 int n;
 144                 if ((sscanf(arg, "%i", &n) == 0) || (n < 0) || (n > 4096))
 145                         argp_usage(state);
 146                 else
 147                         arguments->fill_watermark = n;
 148                 break;
 149         }
 150
 151         default:
 152                 return ARGP_ERR_UNKNOWN;
 153         }
 154
 155         return 0;
 156 }
 157
 158 static struct argp argp = { options, parse_opt, NULL, doc };
 159
 160
 161 static void do_loop(int random_step,
 162                     double poll_timeout)
 163 {
 164         unsigned char buf[FIPS_RNG_BUFFER_SIZE];
 165         unsigned char *p;
 166         int fips;
 167
 168         for (;;) {
 169                 xread(buf, sizeof buf);
 170
 171                 fips = fips_run_rng_test(&fipsctx, buf);
 172
 173                 if (fips) {
 174                         message(LOG_DAEMON|LOG_ERR, "failed fips test\n");
 175                         sleep(1);
 176                         continue;
 177                 }
 178
 179                 for (p = buf; p + random_step <= &buf[sizeof buf];
 180                      p += random_step) {
 181                         random_add_entropy(p, random_step);
 182                         random_sleep(poll_timeout);
 183                 }
 184         }
 185 }
 186
 187
 188 int main(int argc, char **argv)
 189 {
 190         argp_parse(&argp, argc, argv, 0, 0, arguments);
 191
 192         /* Init entropy source, and open TRNG device */
 193         init_entropy_source(arguments->rng_name);
 194
 195         /* Init entropy sink and open random device */
 196         init_kernel_rng(arguments->random_name);
 197
 198         if (arguments->daemon) {
 199                 am_daemon = 1;
 200
 201                 if (daemon(0, 0) < 0) {
 202                         fprintf(stderr, "can't daemonize: %s\n",
 203                                 strerror(errno));
 204                         return 1;
 205                 }
 206
 207                 openlog("rngd", 0, LOG_DAEMON);
 208         }
 209
 210         do_loop(arguments->random_step,
 211                 arguments->poll_timeout ? : -1.0);
 212
 213         return 0;
 214 }