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 Lesser General Public License as published by
10 the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
18 You should have received a copy of the GNU Lesser General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
32 #define POOL_SIZE_MIN 512
34 int main(int argc, char *argv[]) {
35 int seed_fd = -1, random_fd = -1;
36 int ret = EXIT_FAILURE;
43 log_error("This program requires one argument.");
47 log_set_target(LOG_TARGET_AUTO);
48 log_parse_environment();
53 /* Read pool size, if possible */
54 if ((f = fopen("/proc/sys/kernel/random/poolsize", "re"))) {
55 if (fscanf(f, "%zu", &buf_size) > 0) {
56 /* poolsize is in bits on 2.6, but we want bytes */
63 if (buf_size <= POOL_SIZE_MIN)
64 buf_size = POOL_SIZE_MIN;
66 if (!(buf = malloc(buf_size))) {
67 log_error("Failed to allocate buffer.");
71 if (mkdir_parents(RANDOM_SEED, 0755) < 0) {
72 log_error("Failed to create directories parents of %s: %m", RANDOM_SEED);
76 /* When we load the seed we read it and write it to the device
77 * and then immediately update the saved seed with new data,
78 * to make sure the next boot gets seeded differently. */
80 if (streq(argv[1], "load")) {
82 if ((seed_fd = open(RANDOM_SEED, O_RDWR|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600)) < 0) {
83 if ((seed_fd = open(RANDOM_SEED, O_RDONLY|O_CLOEXEC|O_NOCTTY)) < 0) {
84 log_error("Failed to open random seed: %m");
89 if ((random_fd = open("/dev/urandom", O_RDWR|O_CLOEXEC|O_NOCTTY, 0600)) < 0) {
90 if ((random_fd = open("/dev/urandom", O_WRONLY|O_CLOEXEC|O_NOCTTY, 0600)) < 0) {
91 log_error("Failed to open /dev/urandom: %m");
96 if ((r = loop_read(seed_fd, buf, buf_size, false)) <= 0) {
99 log_error("Failed to read seed file: %m");
101 lseek(seed_fd, 0, SEEK_SET);
103 if ((r = loop_write(random_fd, buf, (size_t) r, false)) <= 0)
104 log_error("Failed to write seed to /dev/random: %s", r < 0 ? strerror(errno) : "short write");
107 } else if (streq(argv[1], "save")) {
109 if ((seed_fd = open(RANDOM_SEED, O_WRONLY|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600)) < 0) {
110 log_error("Failed to open random seed: %m");
114 if ((random_fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY)) < 0) {
115 log_error("Failed to open /dev/urandom: %m");
119 log_error("Unknown verb %s.", argv[1]);
123 /* This is just a safety measure. Given that we are root and
124 * most likely created the file ourselves the mode and owner
125 * should be correct anyway. */
126 fchmod(seed_fd, 0600);
127 fchown(seed_fd, 0, 0);
129 if ((r = loop_read(random_fd, buf, buf_size, false)) <= 0)
130 log_error("Failed to read new seed from /dev/urandom: %s", r < 0 ? strerror(errno) : "EOF");
132 if ((r = loop_write(seed_fd, buf, (size_t) r, false)) <= 0)
133 log_error("Failed to write new random seed file: %s", r < 0 ? strerror(errno) : "short write");
140 close_nointr_nofail(random_fd);
143 close_nointr_nofail(seed_fd);