1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
4 This file is part of systemd.
6 Copyright 2010 Lennart Poettering
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
13 systemd is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
31 int main(int argc, char *argv[]) {
32 int seed_fd = -1, random_fd = -1;
38 log_error("This program requires one argument.");
42 log_parse_environment();
44 /* When we load the seed we read it and write it to the device
45 * and then immediately update the saved seed with new data,
46 * to make sure the next boot gets seeded differently. */
48 if (streq(argv[1], "load")) {
50 if ((seed_fd = open(RANDOM_SEED, O_RDWR|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600)) < 0) {
51 if ((seed_fd = open(RANDOM_SEED, O_RDONLY|O_CLOEXEC|O_NOCTTY)) < 0) {
52 log_error("Failed to open random seed: %m");
57 if ((random_fd = open("/dev/urandom", O_RDWR|O_CLOEXEC|O_NOCTTY, 0600)) < 0) {
58 if ((random_fd = open("/dev/urandom", O_WRONLY|O_CLOEXEC|O_NOCTTY, 0600)) < 0) {
59 log_error("Failed to open /dev/urandom: %m");
64 if ((r = loop_read(seed_fd, buf, sizeof(buf), false)) != sizeof(buf))
65 log_error("Failed to read seed file: %s", r < 0 ? strerror(errno) : "EOF");
67 lseek(seed_fd, 0, SEEK_SET);
69 if ((r = loop_write(random_fd, buf, sizeof(buf), false)) != sizeof(buf))
70 log_error("Failed to write seed to /dev/random: %s", r < 0 ? strerror(errno) : "short write");
73 } else if (streq(argv[1], "save")) {
75 if ((seed_fd = open(RANDOM_SEED, O_WRONLY|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600)) < 0) {
76 log_error("Failed to open random seed: %m");
80 if ((random_fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY)) < 0) {
81 log_error("Failed to open /dev/urandom: %m");
85 log_error("Unknown verb %s.", argv[1]);
89 /* This is just a safety measure. Given that we are root and
90 * most likely created the file ourselves the mode and owner
91 * should be correct anyway. */
92 fchmod(seed_fd, 0600);
93 fchown(seed_fd, 0, 0);
95 if ((r = loop_read(random_fd, buf, sizeof(buf), false)) != sizeof(buf))
96 log_error("Failed to read new seed from /dev/urandom: %s", r < 0 ? strerror(errno) : "EOF");
98 if ((r = loop_write(seed_fd, buf, sizeof(buf), false)) != sizeof(buf))
99 log_error("Failed to write new random seed file: %s", r < 0 ? strerror(errno) : "short write");
106 close_nointr_nofail(random_fd);
109 close_nointr_nofail(seed_fd);