summaryrefslogtreecommitdiff
path: root/src/systemd-random-seed
diff options
context:
space:
mode:
Diffstat (limited to 'src/systemd-random-seed')
-rw-r--r--src/systemd-random-seed/Makefile48
-rw-r--r--src/systemd-random-seed/random-seed.c176
2 files changed, 224 insertions, 0 deletions
diff --git a/src/systemd-random-seed/Makefile b/src/systemd-random-seed/Makefile
new file mode 100644
index 0000000000..80f122dd73
--- /dev/null
+++ b/src/systemd-random-seed/Makefile
@@ -0,0 +1,48 @@
+# -*- Mode: makefile; indent-tabs-mode: t -*-
+#
+# This file is part of systemd.
+#
+# Copyright 2010-2012 Lennart Poettering
+# Copyright 2010-2012 Kay Sievers
+# Copyright 2013 Zbigniew Jędrzejewski-Szmek
+# Copyright 2013 David Strauss
+# Copyright 2016 Luke Shumaker
+#
+# systemd is free software; you can redistribute it and/or modify it
+# under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation; either version 2.1 of the License, or
+# (at your option) any later version.
+#
+# systemd 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
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with systemd; If not, see <http://www.gnu.org/licenses/>.
+include $(dir $(lastword $(MAKEFILE_LIST)))/../../config.mk
+include $(topsrcdir)/build-aux/Makefile.head.mk
+
+ifneq ($(ENABLE_RANDOMSEED),)
+libexec_PROGRAMS += \
+ systemd-random-seed
+
+nodist_systemunit_DATA += \
+ units/systemd-random-seed.service
+
+systemd_random_seed_SOURCES = \
+ src/random-seed/random-seed.c
+
+systemd_random_seed_LDADD = \
+ libshared.la
+
+SYSINIT_TARGET_WANTS += \
+ systemd-random-seed.service
+
+endif # ENABLE_RANDOMSEED
+
+EXTRA_DIST += \
+ units/systemd-random-seed.service.in
+
+$(eval $(value automake2autothing))
+include $(topsrcdir)/build-aux/Makefile.tail.mk
diff --git a/src/systemd-random-seed/random-seed.c b/src/systemd-random-seed/random-seed.c
new file mode 100644
index 0000000000..6748bb9dd3
--- /dev/null
+++ b/src/systemd-random-seed/random-seed.c
@@ -0,0 +1,176 @@
+/***
+ This file is part of systemd.
+
+ Copyright 2010 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "fd-util.h"
+#include "io-util.h"
+#include "log.h"
+#include "mkdir.h"
+#include "string-util.h"
+#include "util.h"
+
+#define POOL_SIZE_MIN 512
+
+int main(int argc, char *argv[]) {
+ _cleanup_close_ int seed_fd = -1, random_fd = -1;
+ _cleanup_free_ void* buf = NULL;
+ size_t buf_size = 0;
+ ssize_t k;
+ int r, open_rw_error;
+ FILE *f;
+ bool refresh_seed_file = true;
+
+ if (argc != 2) {
+ log_error("This program requires one argument.");
+ return EXIT_FAILURE;
+ }
+
+ log_set_target(LOG_TARGET_AUTO);
+ log_parse_environment();
+ log_open();
+
+ umask(0022);
+
+ /* Read pool size, if possible */
+ f = fopen("/proc/sys/kernel/random/poolsize", "re");
+ if (f) {
+ if (fscanf(f, "%zu", &buf_size) > 0)
+ /* poolsize is in bits on 2.6, but we want bytes */
+ buf_size /= 8;
+
+ fclose(f);
+ }
+
+ if (buf_size <= POOL_SIZE_MIN)
+ buf_size = POOL_SIZE_MIN;
+
+ buf = malloc(buf_size);
+ if (!buf) {
+ r = log_oom();
+ goto finish;
+ }
+
+ r = mkdir_parents_label(RANDOM_SEED, 0755);
+ if (r < 0) {
+ log_error_errno(r, "Failed to create directory " RANDOM_SEED_DIR ": %m");
+ goto finish;
+ }
+
+ /* When we load the seed we read it and write it to the device
+ * and then immediately update the saved seed with new data,
+ * to make sure the next boot gets seeded differently. */
+
+ if (streq(argv[1], "load")) {
+
+ seed_fd = open(RANDOM_SEED, O_RDWR|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600);
+ open_rw_error = -errno;
+ if (seed_fd < 0) {
+ refresh_seed_file = false;
+
+ seed_fd = open(RANDOM_SEED, O_RDONLY|O_CLOEXEC|O_NOCTTY);
+ if (seed_fd < 0) {
+ bool missing = errno == ENOENT;
+
+ log_full_errno(missing ? LOG_DEBUG : LOG_ERR,
+ open_rw_error, "Failed to open " RANDOM_SEED " for writing: %m");
+ r = log_full_errno(missing ? LOG_DEBUG : LOG_ERR,
+ errno, "Failed to open " RANDOM_SEED " for reading: %m");
+ if (missing)
+ r = 0;
+
+ goto finish;
+ }
+ }
+
+ random_fd = open("/dev/urandom", O_RDWR|O_CLOEXEC|O_NOCTTY, 0600);
+ if (random_fd < 0) {
+ random_fd = open("/dev/urandom", O_WRONLY|O_CLOEXEC|O_NOCTTY, 0600);
+ if (random_fd < 0) {
+ r = log_error_errno(errno, "Failed to open /dev/urandom: %m");
+ goto finish;
+ }
+ }
+
+ k = loop_read(seed_fd, buf, buf_size, false);
+ if (k < 0)
+ r = log_error_errno(k, "Failed to read seed from " RANDOM_SEED ": %m");
+ else if (k == 0) {
+ r = 0;
+ log_debug("Seed file " RANDOM_SEED " not yet initialized, proceeding.");
+ } else {
+ (void) lseek(seed_fd, 0, SEEK_SET);
+
+ r = loop_write(random_fd, buf, (size_t) k, false);
+ if (r < 0)
+ log_error_errno(r, "Failed to write seed to /dev/urandom: %m");
+ }
+
+ } else if (streq(argv[1], "save")) {
+
+ seed_fd = open(RANDOM_SEED, O_WRONLY|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600);
+ if (seed_fd < 0) {
+ r = log_error_errno(errno, "Failed to open " RANDOM_SEED ": %m");
+ goto finish;
+ }
+
+ random_fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY);
+ if (random_fd < 0) {
+ r = log_error_errno(errno, "Failed to open /dev/urandom: %m");
+ goto finish;
+ }
+
+ } else {
+ log_error("Unknown verb '%s'.", argv[1]);
+ r = -EINVAL;
+ goto finish;
+ }
+
+ if (refresh_seed_file) {
+
+ /* This is just a safety measure. Given that we are root and
+ * most likely created the file ourselves the mode and owner
+ * should be correct anyway. */
+ (void) fchmod(seed_fd, 0600);
+ (void) fchown(seed_fd, 0, 0);
+
+ k = loop_read(random_fd, buf, buf_size, false);
+ if (k < 0) {
+ r = log_error_errno(k, "Failed to read new seed from /dev/urandom: %m");
+ goto finish;
+ }
+ if (k == 0) {
+ log_error("Got EOF while reading from /dev/urandom.");
+ r = -EIO;
+ goto finish;
+ }
+
+ r = loop_write(seed_fd, buf, (size_t) k, false);
+ if (r < 0)
+ log_error_errno(r, "Failed to write new random seed file: %m");
+ }
+
+finish:
+ return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
+}