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/* gcryptrnd.c - Libgcrypt Random Number Daemon
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* Copyright (C) 2006 Free Software Foundation, Inc.
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* Gcryptend is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published
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* by the Free Software Foundation; either version 2 of the License,
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* or (at your option) any later version.
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* Gcryptrnd is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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/* We require vsyslog pth
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We need to test for: setrlimit
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We should also prioritize requests. This is best done by putting
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the requests into queues and have a main thread processing these
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#include <sys/times.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#define PGM "gcryptrnd"
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#define MYVERSION_LINE PGM " (Libgcrypt) " VERSION
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#define BUGREPORT_LINE "\nReport bugs to <bug-libgcrypt@gnupg.org>.\n"
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/* Pth wrapper function definitions. */
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GCRY_THREAD_OPTION_PTH_IMPL;
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/* Flag set to true if we have been daemonized. */
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static int running_detached;
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/* Flag indicating that a shutdown has been requested. */
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static int shutdown_pending;
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/* Counter for active connections. */
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static int active_connections;
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/* Local prototypes. */
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static void serve (int listen_fd);
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/* To avoid that a compiler optimizes certain memset calls away, these
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macros may be used instead. */
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#define wipememory2(_ptr,_set,_len) do { \
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volatile char *_vptr=(volatile char *)(_ptr); \
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size_t _vlen=(_len); \
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while(_vlen) { *_vptr=(_set); _vptr++; _vlen--; } \
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#define wipememory(_ptr,_len) wipememory2(_ptr,0,_len)
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/* Error printing utility. PRIORITY should be one of syslog's
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priority levels. This fucntions prints to the stderro or syslog
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depending on whether we are already daemonized. */
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logit (int priority, const char *format, ...)
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va_start (arg_ptr, format) ;
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vsyslog (priority, format, arg_ptr);
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fputs (PGM ": ", stderr);
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vfprintf (stderr, format, arg_ptr);
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/* Callback used by libgcrypt for logging. */
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my_gcry_logger (void *dummy, int level, const char *format, va_list arg_ptr)
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/* Map the log levels. */
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case GCRY_LOG_CONT: level = LOG_INFO /* FIXME */; break;
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case GCRY_LOG_INFO: level = LOG_INFO; break;
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case GCRY_LOG_WARN: level = LOG_WARNING; break;
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case GCRY_LOG_ERROR:level = LOG_ERR; break;
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case GCRY_LOG_FATAL:level = LOG_CRIT; break;
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case GCRY_LOG_BUG: level = LOG_CRIT; break;
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case GCRY_LOG_DEBUG:level = LOG_DEBUG; break;
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default: level = LOG_ERR; break;
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if (running_detached)
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vsyslog (level, format, arg_ptr);
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fputs (PGM ": ", stderr);
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vfprintf (stderr, format, arg_ptr);
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if (!*format || format[strlen (format)-1] != '\n')
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/* The cleanup handler - used to wipe out the secure memory. */
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gcry_control (GCRYCTL_TERM_SECMEM );
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/* Make us a daemon and open the syslog. */
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if (pid == (pid_t)-1)
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logit (LOG_CRIT, "fork failed: %s", strerror (errno));
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logit (LOG_CRIT, "setsid() failed: %s", strerror(errno));
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signal (SIGHUP, SIG_IGN);
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if (pid == (pid_t)-1)
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logit (LOG_CRIT, PGM ": second fork failed: %s", strerror (errno));
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exit (0); /* First child exits. */
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running_detached = 1;
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logit (LOG_CRIT, "chdir(\"/\") failed: %s", strerror (errno));
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for (i=0; i <= 2; i++)
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openlog (PGM, LOG_PID, LOG_DAEMON);
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disable_core_dumps (void)
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#ifdef HAVE_SETRLIMIT
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if (getrlimit (RLIMIT_CORE, &limit))
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if( !setrlimit (RLIMIT_CORE, &limit) )
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if (errno != EINVAL && errno != ENOSYS)
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logit (LOG_ERR, "can't disable core dumps: %s\n", strerror (errno));
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#endif /* HAVE_SETRLIMIT */
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print_version (int with_help)
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fputs (MYVERSION_LINE "\n"
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"Copyright (C) 2006 Free Software Foundation, Inc.\n"
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"License GPLv2+: GNU GPL version 2 or later "
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"<http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>\n"
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"This is free software: you are free to change and redistribute it.\n"
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"There is NO WARRANTY, to the extent permitted by law.\n",
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"Usage: " PGM " [OPTIONS] [SOCKETNAME]\n"
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"Start Libgcrypt's random number daemon listening"
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" on socket SOCKETNAME\n"
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"SOCKETNAME defaults to XXX\n"
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" --no-detach do not deatach from the console\n"
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" --version print version of the program and exit\n"
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" --help display this help and exit\n"
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BUGREPORT_LINE, stdout );
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fputs ("usage: " PGM " [OPTIONS] [SOCKETNAME]\n", stderr);
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fputs (" (use --help to display options)\n", stderr);
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main (int argc, char **argv)
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struct sockaddr_un *srvr_addr;
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const char *socketname = "/var/run/libgcrypt/S.gcryptrnd";
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while (argc && **argv == '-' && (*argv)[1] == '-')
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else if (!strcmp (*argv, "--version"))
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else if (!strcmp (*argv, "--help"))
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else if (!strcmp (*argv, "--no-detach"))
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socketname = argv[0];
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signal (SIGPIPE, SIG_IGN);
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logit (LOG_NOTICE, "started version " VERSION );
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/* Libgcrypt requires us to register the threading model before we
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do anything else with it. Note that this also calls pth_init. We
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do the initialization while already running as a daemon to avoid
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overhead with double initialization of Libgcrypt. */
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err = gcry_control (GCRYCTL_SET_THREAD_CBS, &gcry_threads_pth);
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logit (LOG_CRIT, "can't register GNU Pth with Libgcrypt: %s",
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/* Check that the libgcrypt version is sufficient. */
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if (!gcry_check_version (VERSION) )
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logit (LOG_CRIT, "libgcrypt is too old (need %s, have %s)",
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VERSION, gcry_check_version (NULL) );
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/* Register the logging callback and tell Libcgrypt to put the
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random pool into secure memory. */
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gcry_set_log_handler (my_gcry_logger, NULL);
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gcry_control (GCRYCTL_USE_SECURE_RNDPOOL);
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/* Obviously we don't want to allow any core dumps. */
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disable_core_dumps ();
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/* Initialize the secure memory stuff which will also drop any extra
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privileges we have. */
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gcry_control (GCRYCTL_INIT_SECMEM, 16384, 0);
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/* Register a cleanup handler. */
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/* Create and listen on the socket. */
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fd = socket (AF_UNIX, SOCK_STREAM, 0);
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logit (LOG_CRIT, "can't create socket: %s", strerror (errno));
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srvr_addr = gcry_xmalloc (sizeof *srvr_addr);
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memset (srvr_addr, 0, sizeof *srvr_addr);
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srvr_addr->sun_family = AF_UNIX;
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if (strlen (socketname) + 1 >= sizeof (srvr_addr->sun_path))
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logit (LOG_CRIT, "socket name `%s' too long", socketname);
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strcpy (srvr_addr->sun_path, socketname);
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addrlen = (offsetof (struct sockaddr_un, sun_path)
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+ strlen (srvr_addr->sun_path) + 1);
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rc = bind (fd, (struct sockaddr*) srvr_addr, addrlen);
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if (rc == -1 && errno == EADDRINUSE)
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rc = bind (fd, (struct sockaddr*) srvr_addr, addrlen);
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logit (LOG_CRIT, "error binding socket to `%s': %s",
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srvr_addr->sun_path, strerror (errno));
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if (listen (fd, 5 ) == -1)
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logit (LOG_CRIT, "listen() failed: %s", strerror (errno));
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logit (LOG_INFO, "listening on socket `%s', fd=%d",
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srvr_addr->sun_path, fd);
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logit (LOG_NOTICE, "stopped version " VERSION );
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/* Send LENGTH bytes of BUFFER to file descriptor FD. Returns 0 on
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success or another value on write error. */
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writen (int fd, const void *buffer, size_t length)
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ssize_t n = pth_write (fd, buffer, length);
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logit (LOG_ERR, "connection %d: write error: %s",
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fd, strerror (errno));
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return -1; /* write error */
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buffer = (const char*)buffer + n;
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/* Send an error response back. Returns 0 on success. */
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send_error (int fd, int errcode)
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unsigned char buf[2];
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return writen (fd, buf, 2 );
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/* Send a pong response back. Returns 0 on success or another value
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return writen (fd, "\x00\x04pong", 6);
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/* Send a nonce of size LENGTH back. Return 0 on success. */
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send_nonce (int fd, int length)
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unsigned char buf[2+255];
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assert (length >= 0 && length <= 255);
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gcry_create_nonce (buf+2, length);
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rc = writen (fd, buf, 2+length );
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wipememory (buf+2, length);
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/* Send a random of size LENGTH with quality LEVEL back. Return 0 on
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send_random (int fd, int length, int level)
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unsigned char buf[2+255];
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assert (length >= 0 && length <= 255);
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assert (level == GCRY_STRONG_RANDOM || level == GCRY_VERY_STRONG_RANDOM);
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/* Note that we don't bother putting the random stuff into secure
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memory because this daemon is anyway intended to be run under
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root and it is questionable whether the kernel buffers etc. are
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equally well protected. */
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gcry_randomize (buf+2, length, level);
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rc = writen (fd, buf, 2+length );
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wipememory (buf+2, length);
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/* Main processing loop for a connection.
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A request is made up of:
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1 byte Total length of request; must be 3
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12 = GetVeryStrongRandom
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(all other values are reserved)
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1 byte Number of requested bytes.
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This is ignored for command Ping.
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A response is made up of:
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0 = Everything is fine
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(For a bad request the connection will simply be closed)
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1 byte Length of data
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The requests are read as long as the connection is open.
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connection_loop (int fd)
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unsigned char request[3];
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for (nleft=3, p=request; nleft > 0; )
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n = pth_read (fd, p, nleft);
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if (!n && p == request)
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return; /* Client terminated connection. */
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logit (LOG_ERR, "connection %d: read error: %s",
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fd, n? strerror (errno) : "Unexpected EOF");
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logit (LOG_ERR, "connection %d: invalid length (%d) of request",
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case 10: /* GetNonce */
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rc = send_nonce (fd, request[2]);
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case 11: /* GetStrongRandom */
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rc = send_random (fd, request[2], GCRY_STRONG_RANDOM);
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case 12: /* GetVeryStrongRandom */
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rc = send_random (fd, request[2], GCRY_VERY_STRONG_RANDOM);
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default: /* Invalid command */
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rc = send_error (fd, 1);
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break; /* A write error occured while sending the response. */
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/* Entry point for a connection's thread. */
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connection_thread (void *arg)
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active_connections++;
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logit (LOG_INFO, "connection handler for fd %d started", fd);
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connection_loop (fd);
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logit (LOG_INFO, "connection handler for fd %d terminated", fd);
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active_connections--;
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/* This signal handler is called from the main loop between acepting
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connections. It is called on the regular stack, thus no special
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caution needs to be taken. It returns true to indicate that the
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process should terminate. */
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handle_signal (int signo)
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logit (LOG_NOTICE, "SIGHUP received - re-reading configuration");
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logit (LOG_NOTICE, "SIGUSR1 received - no action defined");
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logit (LOG_NOTICE, "SIGUSR2 received - no action defined");
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if (!shutdown_pending)
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logit (LOG_NOTICE, "SIGTERM received - shutting down ...");
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logit (LOG_NOTICE, "SIGTERM received - still %d active connections",
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if (shutdown_pending > 2)
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logit (LOG_NOTICE, "shutdown forced");
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logit (LOG_NOTICE, "SIGINT received - immediate shutdown");
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logit (LOG_NOTICE, "signal %d received - no action defined\n", signo);
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/* Main server loop. This is called with the FD of the listening
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serve (int listen_fd)
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struct sockaddr_un paddr;
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socklen_t plen = sizeof (paddr);
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tattr = pth_attr_new();
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pth_attr_set (tattr, PTH_ATTR_JOINABLE, 0);
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pth_attr_set (tattr, PTH_ATTR_STACK_SIZE, 256*1024);
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pth_attr_set (tattr, PTH_ATTR_NAME, "connection");
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sigaddset (&sigs, SIGHUP);
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sigaddset (&sigs, SIGUSR1);
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sigaddset (&sigs, SIGUSR2);
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sigaddset (&sigs, SIGINT);
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sigaddset (&sigs, SIGTERM);
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ev = pth_event (PTH_EVENT_SIGS, &sigs, &signo);
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if (shutdown_pending)
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if (!active_connections)
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/* Do not accept anymore connections but wait for existing
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connections to terminate. */
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if (pth_event_occurred (ev) && signo)
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if (handle_signal (signo))
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break; /* Stop the loop. */
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gcry_fast_random_poll ();
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fd = pth_accept_ev (listen_fd, (struct sockaddr *)&paddr, &plen, ev);
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if (pth_event_occurred (ev))
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if (handle_signal (signo))
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break; /* Stop the loop. */
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logit (LOG_WARNING, "accept failed: %s - waiting 1s\n",
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gcry_fast_random_poll ();
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if (!pth_spawn (tattr, connection_thread, (void*)fd))
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logit (LOG_ERR, "error spawning connection handler: %s\n",
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pth_event_free (ev, PTH_FREE_ALL);
added
removed
src/gcryptrnd.c
