1 files changed, 244 insertions, 0 deletions
diff --git a/lib/random.c b/lib/random.c
new file mode 100644
index 0000000..0dfcff9
--- /dev/null
+++ b/lib/random.c
@@ -0,0 +1,244 @@
+/*
+ * cryptsetup kernel RNG access functions
+ *
+ * Copyright (C) 2010-2023 Red Hat, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/select.h>
+
+#include "libcryptsetup.h"
+#include "internal.h"
+
+static int random_initialised = 0;
+
+#define URANDOM_DEVICE	"/dev/urandom"
+static int urandom_fd = -1;
+
+#define RANDOM_DEVICE	"/dev/random"
+static int random_fd = -1;
+
+/* Read random chunk - gathered data usually appears with this granularity */
+#define RANDOM_DEVICE_CHUNK	8
+
+/* Timeout to print warning if no random data (entropy) */
+#define RANDOM_DEVICE_TIMEOUT	5
+
+/* URANDOM_DEVICE access */
+static int _get_urandom(char *buf, size_t len)
+{
+	int r;
+	size_t old_len = len;
+	char *old_buf = buf;
+
+	assert(urandom_fd != -1);
+
+	while (len) {
+		r = read(urandom_fd, buf, len);
+		if (r == -1 && errno != EINTR)
+			return -EINVAL;
+		if (r > 0) {
+			len -= r;
+			buf += r;
+		}
+	}
+
+	assert(len == 0);
+	assert((size_t)(buf - old_buf) == old_len);
+
+	return 0;
+}
+
+static void _get_random_progress(struct crypt_device *ctx, int warn,
+				 size_t expected_len, size_t read_len)
+{
+	if (warn)
+		log_std(ctx,
+			_("System is out of entropy while generating volume key.\n"
+			  "Please move mouse or type some text in another window "
+			  "to gather some random events.\n"));
+
+	log_std(ctx, _("Generating key (%d%% done).\n"),
+		(int)((expected_len - read_len) * 100 / expected_len));
+}
+
+/* RANDOM_DEVICE access */
+static int _get_random(struct crypt_device *ctx, char *buf, size_t len)
+{
+	int r, warn_once = 1;
+	size_t n, old_len = len;
+	char *old_buf = buf;
+	fd_set fds;
+	struct timeval tv;
+
+	assert(random_fd != -1);
+
+	while (len) {
+		FD_ZERO(&fds);
+		FD_SET(random_fd, &fds);
+
+		tv.tv_sec = RANDOM_DEVICE_TIMEOUT;
+		tv.tv_usec = 0;
+
+		r = select(random_fd + 1, &fds, NULL, NULL, &tv);
+		if(r == -1)
+			return -EINVAL;
+
+		if(!r) {
+			_get_random_progress(ctx, warn_once, old_len, len);
+			warn_once = 0;
+			continue;
+		}
+
+		do {
+			n = RANDOM_DEVICE_CHUNK;
+			if (len < RANDOM_DEVICE_CHUNK)
+				n = len;
+
+			r = read(random_fd, buf, n);
+
+			if (r == -1 && errno == EINTR) {
+				r = 0;
+				continue;
+			}
+
+			/* bogus read? */
+			if(r > (int)n)
+				return -EINVAL;
+
+			/* random device is opened with O_NONBLOCK, EAGAIN is expected */
+			if (r == -1 && (errno != EAGAIN && errno != EWOULDBLOCK))
+				return -EINVAL;
+
+			if (r > 0) {
+				len -= r;
+				buf += r;
+			}
+		} while (len && r > 0);
+	}
+
+	assert(len == 0);
+	assert((size_t)(buf - old_buf) == old_len);
+
+	if (!warn_once)
+		_get_random_progress(ctx, 0, old_len, len);
+
+	return 0;
+}
+/* Initialisation of both RNG file descriptors is mandatory */
+int crypt_random_init(struct crypt_device *ctx)
+{
+	if (random_initialised)
+		return 0;
+
+	/* Used for CRYPT_RND_NORMAL */
+	if(urandom_fd == -1)
+		urandom_fd = open(URANDOM_DEVICE, O_RDONLY | O_CLOEXEC);
+	if(urandom_fd == -1)
+		goto err;
+
+	/* Used for CRYPT_RND_KEY */
+	if(random_fd == -1)
+		random_fd = open(RANDOM_DEVICE, O_RDONLY | O_NONBLOCK | O_CLOEXEC);
+	if(random_fd == -1)
+		goto err;
+
+	if (crypt_fips_mode())
+		log_verbose(ctx, _("Running in FIPS mode."));
+
+	random_initialised = 1;
+	return 0;
+err:
+	crypt_random_exit();
+	log_err(ctx, _("Fatal error during RNG initialisation."));
+	return -ENOSYS;
+}
+
+/* coverity[ -taint_source : arg-1 ] */
+int crypt_random_get(struct crypt_device *ctx, char *buf, size_t len, int quality)
+{
+	int status, rng_type;
+
+	switch(quality) {
+	case CRYPT_RND_NORMAL:
+		status = _get_urandom(buf, len);
+		break;
+	case CRYPT_RND_SALT:
+		if (crypt_fips_mode())
+			status = crypt_backend_rng(buf, len, quality, 1);
+		else
+			status = _get_urandom(buf, len);
+		break;
+	case CRYPT_RND_KEY:
+		if (crypt_fips_mode()) {
+			status = crypt_backend_rng(buf, len, quality, 1);
+			break;
+		}
+		rng_type = ctx ? crypt_get_rng_type(ctx) :
+				 crypt_random_default_key_rng();
+		switch (rng_type) {
+		case CRYPT_RNG_URANDOM:
+			status = _get_urandom(buf, len);
+			break;
+		case CRYPT_RNG_RANDOM:
+			status = _get_random(ctx, buf, len);
+			break;
+		default:
+			abort();
+		}
+		break;
+	default:
+		log_err(ctx, _("Unknown RNG quality requested."));
+		return -EINVAL;
+	}
+
+	if (status)
+		log_err(ctx, _("Error reading from RNG."));
+
+	return status;
+}
+
+void crypt_random_exit(void)
+{
+	random_initialised = 0;
+
+	if(random_fd != -1) {
+		(void)close(random_fd);
+		random_fd = -1;
+	}
+
+	if(urandom_fd != -1) {
+		(void)close(urandom_fd);
+		urandom_fd = -1;
+	}
+}
+
+int crypt_random_default_key_rng(void)
+{
+	/* coverity[pointless_string_compare] */
+	if (!strcmp(DEFAULT_RNG, RANDOM_DEVICE))
+		return CRYPT_RNG_RANDOM;
+
+	/* coverity[pointless_string_compare] */
+	if (!strcmp(DEFAULT_RNG, URANDOM_DEVICE))
+		return CRYPT_RNG_URANDOM;
+
+	/* RNG misconfiguration is fatal */
+	abort();
+}