/*-*- 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[]) { int seed_fd = -1, random_fd = -1; int ret = EXIT_FAILURE; void* buf; size_t buf_size = 0; ssize_t 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 */ if ((f = fopen("/proc/sys/kernel/random/poolsize", "re"))) { 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; if (!(buf = malloc(buf_size))) { log_error("Failed to allocate buffer."); goto finish; } if (mkdir_parents_label(RANDOM_SEED, 0755) < 0) { log_error("Failed to create directories parents of %s: %m", RANDOM_SEED); 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) { if (r != 0) log_error("Failed to read seed file: %m"); } 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/urandom: %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 = EXIT_SUCCESS; finish: if (random_fd >= 0) close_nointr_nofail(random_fd); if (seed_fd >= 0) close_nointr_nofail(seed_fd); free(buf); return ret; }