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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 General Public License as published by
the Free Software Foundation; either version 2 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
General Public License for more details.
You should have received a copy of the GNU 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"
#define POOL_SIZE_MIN 512
int main(int argc, char *argv[]) {
int seed_fd = -1, random_fd = -1;
int ret = 1;
void* buf;
size_t buf_size = 0;
ssize_t r;
FILE *f;
if (argc != 2) {
log_error("This program requires one argument.");
return 1;
}
log_set_target(LOG_TARGET_SYSLOG_OR_KMSG);
log_parse_environment();
log_open();
/* Read pool size, if possible */
if ((f = fopen("/proc/sys/kernel/random/poolsize", "re"))) {
fscanf(f, "%zu", &buf_size);
fclose(f);
}
if (buf_size <= POOL_SIZE_MIN)
buf_size = POOL_SIZE_MIN;
if (!(buf = malloc(buf_size))) {
log_error("Failed to allocate buffer.");
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")) {
if ((seed_fd = open(RANDOM_SEED, O_RDWR|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600)) < 0) {
if ((seed_fd = open(RANDOM_SEED, O_RDONLY|O_CLOEXEC|O_NOCTTY)) < 0) {
log_error("Failed to open random seed: %m");
goto finish;
}
}
if ((random_fd = open("/dev/urandom", O_RDWR|O_CLOEXEC|O_NOCTTY, 0600)) < 0) {
if ((random_fd = open("/dev/urandom", O_WRONLY|O_CLOEXEC|O_NOCTTY, 0600)) < 0) {
log_error("Failed to open /dev/urandom: %m");
goto finish;
}
}
if ((r = loop_read(seed_fd, buf, buf_size, false)) <= 0)
log_error("Failed to read seed file: %s", r < 0 ? strerror(errno) : "EOF");
else {
lseek(seed_fd, 0, SEEK_SET);
if ((r = loop_write(random_fd, buf, (size_t) r, false)) <= 0)
log_error("Failed to write seed to /dev/random: %s", r < 0 ? strerror(errno) : "short write");
}
} else if (streq(argv[1], "save")) {
if ((seed_fd = open(RANDOM_SEED, O_WRONLY|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600)) < 0) {
log_error("Failed to open random seed: %m");
goto finish;
}
if ((random_fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY)) < 0) {
log_error("Failed to open /dev/urandom: %m");
goto finish;
}
} else {
log_error("Unknown verb %s.", argv[1]);
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);
if ((r = loop_read(random_fd, buf, buf_size, false)) <= 0)
log_error("Failed to read new seed from /dev/urandom: %s", r < 0 ? strerror(errno) : "EOF");
else {
if ((r = loop_write(seed_fd, buf, (size_t) r, false)) <= 0)
log_error("Failed to write new random seed file: %s", r < 0 ? strerror(errno) : "short write");
}
ret = 0;
finish:
if (random_fd >= 0)
close_nointr_nofail(random_fd);
if (seed_fd >= 0)
close_nointr_nofail(seed_fd);
free(buf);
return ret;
}
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