--- /dev/null
+/*
+ * Non-physical true random number generator based on timing jitter.
+ *
+ * Copyright Stephan Mueller <smueller@chronox.de>, 2014
+ * Copyright Petr Štetiar <ynezz@true.cz>, 2019
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, and the entire permission notice in its entirety,
+ * including the disclaimer of warranties.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote
+ * products derived from this software without specific prior
+ * written permission.
+ *
+ * ALTERNATIVELY, this product may be distributed under the terms of
+ * the GNU General Public License, in which case the provisions of the GPL are
+ * required INSTEAD OF the above restrictions. (This clause is
+ * necessary due to a potential bad interaction between the GPL and
+ * the restrictions contained in a BSD-style copyright.)
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
+ * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+ * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <sys/ioctl.h>
+#include <linux/random.h>
+
+#include <libubox/uloop.h>
+
+#include "log.h"
+#include "jitterentropy.h"
+
+#define ENTROPYBYTES 32
+#define ENTROPYTHRESH 1024
+#define OVERSAMPLINGFACTOR 2
+#define DEV_RANDOM "/dev/random"
+#define ENTROPYAVAIL "/proc/sys/kernel/random/entropy_avail"
+#define ENTROPYPOOLBYTES (sizeof(struct rand_pool_info) + \
+ (ENTROPYBYTES * OVERSAMPLINGFACTOR * sizeof(char)))
+
+#ifdef URNGD_DEBUG
+unsigned int debug;
+#endif
+
+struct urngd {
+ struct uloop_fd rnd_fd;
+ struct rand_data *ec;
+ struct rand_pool_info *rpi;
+};
+
+static struct urngd urngd_service;
+
+static inline void memset_secure(void *s, int c, size_t n)
+{
+ memset(s, c, n);
+ __asm__ __volatile__("" : : "r" (s) : "memory");
+}
+
+static size_t write_entropy(struct urngd *u, char *buf, size_t len,
+ size_t entropy_bytes)
+{
+ int ret;
+ size_t written = 0;
+
+ /* value is in bits */
+ u->rpi->entropy_count = (entropy_bytes * 8);
+ u->rpi->buf_size = len;
+ memcpy(u->rpi->buf, buf, len);
+ memset(buf, 0, len);
+
+ ret = ioctl(u->rnd_fd.fd, RNDADDENTROPY, u->rpi);
+ if (0 > ret) {
+ ERROR("error injecting entropy: %s\n", strerror(errno));
+ } else {
+ DEBUG(1, "injected %ub (%ub of entropy)\n", len, entropy_bytes);
+ written = len;
+ }
+
+ u->rpi->entropy_count = 0;
+ u->rpi->buf_size = 0;
+ memset(u->rpi->buf, 0, len);
+
+ return written;
+}
+
+static size_t gather_entropy(struct urngd *u)
+{
+ size_t ret = 0;
+ char buf[(ENTROPYBYTES * OVERSAMPLINGFACTOR)];
+
+ if (jent_read_entropy(u->ec, buf, sizeof(buf)) < 0) {
+ ERROR("cannot read entropy\n");
+ return 0;
+ }
+
+ ret = write_entropy(u, buf, sizeof(buf), ENTROPYBYTES);
+ if (sizeof(buf) != ret) {
+ ERROR("injected %lub of entropy, less then %db expected\n",
+ ret, sizeof(buf));
+ } else {
+ ret = sizeof(buf);
+ }
+
+ memset_secure(buf, 0, sizeof(buf));
+ DEBUG(2, DEV_RANDOM " fed with %lub of entropy\n", ret);
+
+ return ret;
+}
+
+static void low_entropy_cb(struct uloop_fd *ufd, unsigned int events)
+{
+ struct urngd *u = container_of(ufd, struct urngd, rnd_fd);
+
+ DEBUG(2, DEV_RANDOM " signals low entropy\n");
+ gather_entropy(u);
+}
+
+static void urngd_done(struct urngd *u)
+{
+ if (u->ec) {
+ jent_entropy_collector_free(u->ec);
+ u->ec = NULL;
+ }
+
+ if (u->rpi) {
+ memset(u->rpi, 0, ENTROPYPOOLBYTES);
+ free(u->rpi);
+ u->rpi = NULL;
+ }
+
+ if (u->rnd_fd.fd) {
+ close(u->rnd_fd.fd);
+ u->rnd_fd.fd = 0;
+ }
+}
+
+static bool urngd_init(struct urngd *u)
+{
+ int ret = jent_entropy_init();
+ if (ret) {
+ ERROR("jent-rng init failed, err: %d\n", ret);
+ return false;
+ }
+
+ u->ec = jent_entropy_collector_alloc(1, 0);
+ if (!u->ec) {
+ ERROR("jent-rng alloc failed\n");
+ return false;
+ }
+
+ u->rpi = malloc(ENTROPYPOOLBYTES);
+ if (!u->rpi) {
+ ERROR("rand pool alloc failed\n");
+ return false;
+ }
+
+ u->rnd_fd.cb = low_entropy_cb;
+ u->rnd_fd.fd = open(DEV_RANDOM, O_WRONLY);
+ if (u->rnd_fd.fd < 1) {
+ ERROR(DEV_RANDOM " open failed: %s", strerror(errno));
+ return false;
+ }
+
+ uloop_fd_add(&u->rnd_fd, ULOOP_READ);
+
+ return true;
+}
+
+static int usage(const char *prog)
+{
+ fprintf(stderr, "Usage: %s [options]\n"
+ "Options:\n"
+#ifdef URNGD_DEBUG
+ " -d <level> Enable debug messages\n"
+#endif
+ " -S Print messages to stdout\n"
+ "\n", prog);
+ return 1;
+}
+
+int main(int argc, char **argv)
+{
+ int ch;
+ int ulog_channels = ULOG_KMSG;
+#ifdef URNGD_DEBUG
+ char *dbglvl = getenv("DBGLVL");
+
+ if (dbglvl) {
+ debug = atoi(dbglvl);
+ unsetenv("DBGLVL");
+ }
+#endif
+
+ while ((ch = getopt(argc, argv, "d:S")) != -1) {
+ switch (ch) {
+#ifdef URNGD_DEBUG
+ case 'd':
+ debug = atoi(optarg);
+ break;
+#endif
+ case 'S':
+ ulog_channels = ULOG_STDIO;
+ break;
+ default:
+ return usage(argv[0]);
+ }
+ }
+
+ if (!urngd_init(&urngd_service))
+ return -1;
+
+ ulog_open(ulog_channels, LOG_DAEMON, "urngd");
+ LOG("v%s started.\n", URNGD_VERSION);
+
+ gather_entropy(&urngd_service);
+
+ uloop_init();
+ uloop_run();
+ uloop_done();
+
+ urngd_done(&urngd_service);
+
+ return 0;
+}
projects / project / urngd.git / commitdiff