diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/random-seed.c | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/src/random-seed.c b/src/random-seed.c new file mode 100644 index 0000000000..91aa6c6b4e --- /dev/null +++ b/src/random-seed.c @@ -0,0 +1,112 @@ +/*-*- 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 General Public License as published by + the Free Software Foundation; either version 2 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 + General Public License for more details. + + You should have received a copy of the GNU 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" + +int main(int argc, char *argv[]) { + int seed_fd = -1, random_fd = -1; + int ret = 1; + uint8_t buf[512]; + ssize_t r; + + if (argc != 2) { + log_error("This program requires one argument."); + return 1; + } + + log_parse_environment(); + + /* 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, sizeof(buf), false)) != sizeof(buf)) + log_error("Failed to read seed file: %s", r < 0 ? strerror(errno) : "EOF"); + else { + lseek(seed_fd, 0, SEEK_SET); + + if ((r = loop_write(random_fd, buf, sizeof(buf), false)) != sizeof(buf)) + 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, sizeof(buf), false)) != sizeof(buf)) + log_error("Failed to read new seed from /dev/urandom: %s", r < 0 ? strerror(errno) : "EOF"); + else { + if ((r = loop_write(seed_fd, buf, sizeof(buf), false)) != sizeof(buf)) + log_error("Failed to write new random seed file: %s", r < 0 ? strerror(errno) : "short write"); + } + + ret = 0; + +finish: + if (random_fd >= 0) + close_nointr_nofail(random_fd); + + if (seed_fd >= 0) + close_nointr_nofail(seed_fd); + + return ret; +} |