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 #include <signal.h>
  49
  50 #include "rngd.h"
  51 #include "fips.h"
  52 #include "exits.h"
  53 #include "rngd_entsource.h"
  54 #include "rngd_linux.h"
  55
  56 /*
  57  * Globals
  58  */
  59
  60 /* Background/daemon mode */
  61 int am_daemon;                          /* Nonzero if we went daemon */
  62
  63 bool server_running = true;             /* set to false, to stop daemon */
  64
  65 /* Command line arguments and processing */
  66 const char *argp_program_version =
  67         "rngd " VERSION "\n"
  68         "Copyright 2001-2004 Jeff Garzik\n"
  69         "Copyright (c) 2001 by Philipp Rumpf\n"
  70         "This is free software; see the source for copying conditions.  There is NO "
  71         "warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.";
  72
  73 const char *argp_program_bug_address = PACKAGE_BUGREPORT;
  74
  75 static char doc[] =
  76         "Check and feed random data from hardware device to kernel entropy pool.\n";
  77
  78 static struct argp_option options[] = {
  79         { "foreground", 'f', 0, 0, "Do not fork and become a daemon" },
  80
  81         { "background", 'b', 0, 0, "Become a daemon (default)" },
  82
  83         { "random-device", 'o', "file", 0,
  84           "Kernel device used for random number output (default: /dev/random)" },
  85
  86         { "rng-device", 'r', "file", 0,
  87           "Kernel device used for random number input (default: /dev/hw_random)" },
  88
  89         { "pid-file", 'p', "file", 0,
  90           "File used for recording daemon PID, and multiple exclusion (default: /var/run/rngd.pid)" },
  91
  92         { "random-step", 's', "nnn", 0,
  93           "Number of bytes written to random-device at a time (default: 64)" },
  94
  95         { "fill-watermark", 'W', "n", 0,
  96           "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" },
  97
  98         { "quiet", 'q', 0, 0, "Suppress error messages" },
  99
 100         { "verbose" ,'v', 0, 0, "Report available entropy sources" },
 101
 102         { "timeout", 't', "nnn", 0,
 103           "Interval written to random-device when the entropy pool is full, in seconds, or 0 to disable (default: 60)" },
 104         { "no-tpm", 'n', "1|0", 0,
 105           "do not use tpm as a source of random number input (default: 0)" },
 106
 107         { 0 },
 108 };
 109
 110 static struct arguments default_arguments = {
 111         .random_name    = "/dev/random",
 112         .pid_file       = "/var/run/rngd.pid",
 113         .poll_timeout   = 60,
 114         .random_step    = 64,
 115         .fill_watermark = 2048,
 116         .daemon         = 1,
 117         .enable_tpm     = 1,
 118         .quiet          = 0,
 119         .verbose        = 0,
 120 };
 121 struct arguments *arguments = &default_arguments;
 122
 123 static struct rng rng_default = {
 124         .rng_name       = "/dev/hw_random",
 125         .rng_fd         = -1,
 126         .xread          = xread,
 127 };
 128
 129 static struct rng rng_tpm = {
 130         .rng_name       = "/dev/tpm0",
 131         .rng_fd         = -1,
 132         .xread          = xread_tpm,
 133 };
 134
 135 struct rng *rng_list;
 136
 137 /*
 138  * command line processing
 139  */
 140 static error_t parse_opt (int key, char *arg, struct argp_state *state)
 141 {
 142         switch(key) {
 143         case 'o':
 144                 arguments->random_name = arg;
 145                 break;
 146         case 'p':
 147                 arguments->pid_file = arg;
 148                 break;
 149         case 'r':
 150                 rng_default.rng_name = arg;
 151                 break;
 152         case 't': {
 153                 float f;
 154                 if (sscanf(arg, "%f", &f) == 0)
 155                         argp_usage(state);
 156                 else
 157                         arguments->poll_timeout = f;
 158                 break;
 159         }
 160
 161         case 'f':
 162                 arguments->daemon = 0;
 163                 break;
 164         case 'b':
 165                 arguments->daemon = 1;
 166                 break;
 167         case 's':
 168                 if (sscanf(arg, "%i", &arguments->random_step) == 0)
 169                         argp_usage(state);
 170                 break;
 171         case 'W': {
 172                 int n;
 173                 if ((sscanf(arg, "%i", &n) == 0) || (n < 0) || (n > 4096))
 174                         argp_usage(state);
 175                 else
 176                         arguments->fill_watermark = n;
 177                 break;
 178         }
 179         case 'q':
 180                 arguments->quiet = 1;
 181                 break;
 182         case 'v':
 183                 arguments->verbose = 1;
 184                 break;
 185         case 'n': {
 186                 int n;
 187                 if ((sscanf(arg,"%i", &n) == 0) || ((n | 1)!=1))
 188                         argp_usage(state);
 189                 else
 190                         arguments->enable_tpm = 0;
 191                 break;
 192         }
 193
 194         default:
 195                 return ARGP_ERR_UNKNOWN;
 196         }
 197
 198         return 0;
 199 }
 200
 201 static struct argp argp = { options, parse_opt, NULL, doc };
 202
 203
 204 static int update_kernel_random(int random_step, double poll_timeout,
 205         unsigned char *buf, fips_ctx_t *fipsctx_in)
 206 {
 207         unsigned char *p;
 208         int fips;
 209
 210         fips = fips_run_rng_test(fipsctx_in, buf);
 211         if (fips) {
 212                 if (!arguments->quiet)
 213                         message(LOG_DAEMON|LOG_ERR, "failed fips test\n");
 214                 return 1;
 215         }
 216
 217         for (p = buf; p + random_step <= &buf[FIPS_RNG_BUFFER_SIZE];
 218                  p += random_step) {
 219                 random_add_entropy(p, random_step);
 220                 random_sleep(poll_timeout);
 221         }
 222         return 0;
 223 }
 224
 225 static void do_loop(int random_step, double poll_timeout)
 226 {
 227         unsigned char buf[FIPS_RNG_BUFFER_SIZE];
 228         int retval = 0;
 229         int no_work = 0;
 230
 231         while (no_work < 100) {
 232                 struct rng *iter;
 233                 bool work_done;
 234
 235                 work_done = false;
 236                 for (iter = rng_list; iter; iter = iter->next)
 237                 {
 238                         int rc;
 239
 240                         if (!server_running)
 241                                 return;
 242
 243                         if (iter->disabled)
 244                                 continue;       /* failed, no work */
 245
 246                         retval = iter->xread(buf, sizeof buf, iter);
 247                         if (retval)
 248                                 continue;       /* failed, no work */
 249
 250                         work_done = true;
 251
 252                         rc = update_kernel_random(random_step,
 253                                              poll_timeout, buf,
 254                                              iter->fipsctx);
 255                         if (rc == 0)
 256                                 continue;       /* succeeded, work done */
 257
 258                         iter->failures++;
 259                         if (iter->failures == MAX_RNG_FAILURES) {
 260                                 if (!arguments->quiet)
 261                                         message(LOG_DAEMON|LOG_ERR,
 262                                         "too many FIPS failures, disabling entropy source\n");
 263                                 iter->disabled = true;
 264                         }
 265                 }
 266
 267                 if (!work_done)
 268                         no_work++;
 269         }
 270
 271         if (!arguments->quiet)
 272                 message(LOG_DAEMON|LOG_ERR,
 273                 "No entropy sources working, exiting rngd\n");
 274 }
 275
 276 static void term_signal(int signo)
 277 {
 278         server_running = false;
 279 }
 280
 281 int main(int argc, char **argv)
 282 {
 283         int rc_rng = 0;
 284         int rc_tpm = 0;
 285         int pid_fd = -1;
 286
 287         openlog("rngd", 0, LOG_DAEMON);
 288
 289         /* Parsing of commandline parameters */
 290         argp_parse(&argp, argc, argv, 0, 0, arguments);
 291
 292         /* Init entropy sources, and open TRNG device */
 293         rc_rng = init_entropy_source(&rng_default);
 294         if (arguments->enable_tpm)
 295                 rc_tpm = init_tpm_entropy_source(&rng_tpm);
 296
 297         if (rc_rng && rc_tpm) {
 298                 if (!arguments->quiet) {
 299                         message(LOG_DAEMON|LOG_ERR,
 300                                 "can't open entropy source(tpm or intel/amd rng)");
 301                         message(LOG_DAEMON|LOG_ERR,
 302                                 "Maybe RNG device modules are not loaded\n");
 303                 }
 304                 return 1;
 305         }
 306
 307         if (arguments->verbose) {
 308                 printf("Available entropy sources:\n");
 309                 if (!rc_rng)
 310                         printf("\tIntel/AMD hardware rng\n");
 311                 if (!rc_tpm)
 312                         printf("\tTPM\n");
 313         }
 314
 315         if (rc_rng
 316                 && (rc_tpm || !arguments->enable_tpm)) {
 317                 if (!arguments->quiet)
 318                         message(LOG_DAEMON|LOG_ERR,
 319                 "No entropy source available, shutting down\n");
 320                 return 1;
 321         }
 322
 323         /* Init entropy sink and open random device */
 324         init_kernel_rng(arguments->random_name);
 325
 326         if (arguments->daemon) {
 327                 am_daemon = 1;
 328
 329                 if (daemon(0, 0) < 0) {
 330                         if(!arguments->quiet)
 331                                 fprintf(stderr, "can't daemonize: %s\n",
 332                                 strerror(errno));
 333                         return 1;
 334                 }
 335
 336                 /* require valid, locked PID file to proceed */
 337                 pid_fd = write_pid_file(arguments->pid_file);
 338                 if (pid_fd < 0)
 339                         return 1;
 340
 341                 signal(SIGHUP, SIG_IGN);
 342                 signal(SIGPIPE, SIG_IGN);
 343                 signal(SIGINT, term_signal);
 344                 signal(SIGTERM, term_signal);
 345         }
 346
 347         do_loop(arguments->random_step,
 348                 arguments->poll_timeout ? : -1.0);
 349
 350         if (pid_fd >= 0)
 351                 unlink(arguments->pid_file);
 352
 353         return 0;
 354 }