diff options
Diffstat (limited to 'src/random-seed/random-seed.c')
| -rw-r--r-- | src/random-seed/random-seed.c | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/src/random-seed/random-seed.c b/src/random-seed/random-seed.c new file mode 100644 index 0000000000..d1cab8b87a --- /dev/null +++ b/src/random-seed/random-seed.c @@ -0,0 +1,148 @@ +/*-*- 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(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/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 = 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; +} |