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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
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 <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <sys/stat.h>
#include "log.h"
#include "util.h"
#include "mkdir.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;
FILE *f;
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("Failed to create parent directory of " RANDOM_SEED ": %s", strerror(-r));
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);
if (seed_fd < 0) {
seed_fd = open(RANDOM_SEED, O_RDONLY|O_CLOEXEC|O_NOCTTY);
if (seed_fd < 0) {
log_error("Failed to open random seed: %m");
r = -errno;
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) {
log_error("Failed to open /dev/urandom: %m");
r = -errno;
goto finish;
}
}
k = loop_read(seed_fd, buf, buf_size, false);
if (k <= 0) {
if (r != 0)
log_error("Failed to read seed file: %m");
r = k == 0 ? -EIO : (int) k;
} else {
lseek(seed_fd, 0, SEEK_SET);
k = loop_write(random_fd, buf, (size_t) k, false);
if (k <= 0) {
log_error("Failed to write seed to /dev/urandom: %s", r < 0 ? strerror(-r) : "short write");
r = k == 0 ? -EIO : (int) k;
}
}
} else if (streq(argv[1], "save")) {
seed_fd = open(RANDOM_SEED, O_WRONLY|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600);
if (seed_fd < 0) {
log_error("Failed to open random seed: %m");
r = -errno;
goto finish;
}
random_fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY);
if (random_fd < 0) {
log_error("Failed to open /dev/urandom: %m");
r = -errno;
goto finish;
}
} else {
log_error("Unknown verb %s.", argv[1]);
r = -EINVAL;
goto finish;
}
/* 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. */
fchmod(seed_fd, 0600);
fchown(seed_fd, 0, 0);
k = loop_read(random_fd, buf, buf_size, false);
if (k <= 0) {
log_error("Failed to read new seed from /dev/urandom: %s", r < 0 ? strerror(-r) : "EOF");
r = k == 0 ? -EIO : (int) k;
} else {
r = loop_write(seed_fd, buf, (size_t) k, false);
if (r <= 0) {
log_error("Failed to write new random seed file: %s", r < 0 ? strerror(-r) : "short write");
r = k == 0 ? -EIO : (int) k;
}
}
finish:
return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
}
|
