168 lines
5.7 KiB
C
168 lines
5.7 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 Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 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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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser 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 <errno.h>
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#include <fcntl.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include "fd-util.h"
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#include "io-util.h"
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#include "log.h"
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#include "mkdir.h"
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#include "string-util.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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_cleanup_close_ int seed_fd = -1, random_fd = -1;
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_cleanup_free_ void* buf = NULL;
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size_t buf_size = 0;
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ssize_t k;
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int r;
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FILE *f;
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bool refresh_seed_file = true;
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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_AUTO);
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log_parse_environment();
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log_open();
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umask(0022);
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/* Read pool size, if possible */
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f = fopen("/proc/sys/kernel/random/poolsize", "re");
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if (f) {
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if (fscanf(f, "%zu", &buf_size) > 0)
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/* poolsize is in bits on 2.6, but we want bytes */
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buf_size /= 8;
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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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buf = malloc(buf_size);
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if (!buf) {
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r = log_oom();
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goto finish;
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}
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r = mkdir_parents_label(RANDOM_SEED, 0755);
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if (r < 0) {
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log_error_errno(r, "Failed to create directory " RANDOM_SEED_DIR ": %m");
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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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seed_fd = open(RANDOM_SEED, O_RDWR|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600);
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if (seed_fd < 0) {
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seed_fd = open(RANDOM_SEED, O_RDONLY|O_CLOEXEC|O_NOCTTY);
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if (seed_fd < 0) {
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r = log_error_errno(errno, "Failed to open " RANDOM_SEED ": %m");
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goto finish;
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}
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refresh_seed_file = false;
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}
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random_fd = open("/dev/urandom", O_RDWR|O_CLOEXEC|O_NOCTTY, 0600);
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if (random_fd < 0) {
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random_fd = open("/dev/urandom", O_WRONLY|O_CLOEXEC|O_NOCTTY, 0600);
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if (random_fd < 0) {
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r = log_error_errno(errno, "Failed to open /dev/urandom: %m");
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goto finish;
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}
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}
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k = loop_read(seed_fd, buf, buf_size, false);
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if (k < 0)
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r = log_error_errno(k, "Failed to read seed from " RANDOM_SEED ": %m");
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else if (k == 0)
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log_debug("Seed file " RANDOM_SEED " not yet initialized, proceeding.");
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else {
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(void) lseek(seed_fd, 0, SEEK_SET);
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r = loop_write(random_fd, buf, (size_t) k, false);
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if (r < 0)
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log_error_errno(r, "Failed to write seed to /dev/urandom: %m");
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}
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} else if (streq(argv[1], "save")) {
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seed_fd = open(RANDOM_SEED, O_WRONLY|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600);
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if (seed_fd < 0) {
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r = log_error_errno(errno, "Failed to open " RANDOM_SEED ": %m");
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goto finish;
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}
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random_fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY);
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if (random_fd < 0) {
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r = log_error_errno(errno, "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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r = -EINVAL;
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goto finish;
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}
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if (refresh_seed_file) {
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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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(void) fchmod(seed_fd, 0600);
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(void) fchown(seed_fd, 0, 0);
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k = loop_read(random_fd, buf, buf_size, false);
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if (k < 0) {
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r = log_error_errno(k, "Failed to read new seed from /dev/urandom: %m");
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goto finish;
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}
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if (k == 0) {
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log_error("Got EOF while reading from /dev/urandom.");
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r = -EIO;
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goto finish;
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}
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r = loop_write(seed_fd, buf, (size_t) k, false);
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if (r < 0)
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log_error_errno(r, "Failed to write new random seed file: %m");
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}
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finish:
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return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
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}
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