/*-*- 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; bool cleanup_seed_file = true; 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_errno(r, "Failed to create directory " RANDOM_SEED_DIR ": %m"); 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_errno(errno, "Failed to open " RANDOM_SEED ": %m"); r = -errno; goto finish; } cleanup_seed_file = false; } 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_errno(errno, "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_errno(errno, "Failed to read seed from " RANDOM_SEED ": %m"); r = k == 0 ? -EIO : (int) k; } else { lseek(seed_fd, 0, SEEK_SET); r = loop_write(random_fd, buf, (size_t) k, false); if (r < 0) log_error_errno(r, "Failed to write seed to /dev/urandom: %m"); } } 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_errno(errno, "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_errno(errno, "Failed to open /dev/urandom: %m"); r = -errno; goto finish; } } else { log_error("Unknown verb %s.", argv[1]); r = -EINVAL; goto finish; } if (cleanup_seed_file) { /* 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_errno(r, "Failed to write new random seed file: %m"); } } finish: return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS; }