135 lines
4.6 KiB
C
135 lines
4.6 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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/***
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <unistd.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <string.h>
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#include <sys/stat.h>
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#include "log.h"
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#include "util.h"
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#define POOL_SIZE_MIN 512
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int main(int argc, char *argv[]) {
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int seed_fd = -1, random_fd = -1;
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int ret = EXIT_FAILURE;
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void* buf;
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size_t buf_size = 0;
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ssize_t r;
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FILE *f;
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if (argc != 2) {
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log_error("This program requires one argument.");
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return EXIT_FAILURE;
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}
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log_set_target(LOG_TARGET_SYSLOG_OR_KMSG);
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log_parse_environment();
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log_open();
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/* Read pool size, if possible */
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if ((f = fopen("/proc/sys/kernel/random/poolsize", "re"))) {
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fscanf(f, "%zu", &buf_size);
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fclose(f);
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}
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if (buf_size <= POOL_SIZE_MIN)
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buf_size = POOL_SIZE_MIN;
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if (!(buf = malloc(buf_size))) {
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log_error("Failed to allocate buffer.");
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goto finish;
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}
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/* When we load the seed we read it and write it to the device
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* and then immediately update the saved seed with new data,
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* to make sure the next boot gets seeded differently. */
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if (streq(argv[1], "load")) {
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if ((seed_fd = open(RANDOM_SEED, O_RDWR|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600)) < 0) {
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if ((seed_fd = open(RANDOM_SEED, O_RDONLY|O_CLOEXEC|O_NOCTTY)) < 0) {
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log_error("Failed to open random seed: %m");
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goto finish;
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}
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}
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if ((random_fd = open("/dev/urandom", O_RDWR|O_CLOEXEC|O_NOCTTY, 0600)) < 0) {
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if ((random_fd = open("/dev/urandom", O_WRONLY|O_CLOEXEC|O_NOCTTY, 0600)) < 0) {
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log_error("Failed to open /dev/urandom: %m");
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goto finish;
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}
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}
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if ((r = loop_read(seed_fd, buf, buf_size, false)) <= 0)
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log_error("Failed to read seed file: %s", r < 0 ? strerror(errno) : "EOF");
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else {
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lseek(seed_fd, 0, SEEK_SET);
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if ((r = loop_write(random_fd, buf, (size_t) r, false)) <= 0)
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log_error("Failed to write seed to /dev/random: %s", r < 0 ? strerror(errno) : "short write");
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}
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} else if (streq(argv[1], "save")) {
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if ((seed_fd = open(RANDOM_SEED, O_WRONLY|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600)) < 0) {
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log_error("Failed to open random seed: %m");
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goto finish;
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}
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if ((random_fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY)) < 0) {
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log_error("Failed to open /dev/urandom: %m");
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goto finish;
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}
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} else {
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log_error("Unknown verb %s.", argv[1]);
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goto finish;
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}
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/* This is just a safety measure. Given that we are root and
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* most likely created the file ourselves the mode and owner
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* should be correct anyway. */
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fchmod(seed_fd, 0600);
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fchown(seed_fd, 0, 0);
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if ((r = loop_read(random_fd, buf, buf_size, false)) <= 0)
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log_error("Failed to read new seed from /dev/urandom: %s", r < 0 ? strerror(errno) : "EOF");
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else {
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if ((r = loop_write(seed_fd, buf, (size_t) r, false)) <= 0)
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log_error("Failed to write new random seed file: %s", r < 0 ? strerror(errno) : "short write");
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}
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ret = EXIT_SUCCESS;
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finish:
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if (random_fd >= 0)
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close_nointr_nofail(random_fd);
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if (seed_fd >= 0)
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close_nointr_nofail(seed_fd);
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free(buf);
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return ret;
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}
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