diff options
Diffstat (limited to 'src/grp-initprogs/systemd-random-seed/random-seed.c')
| -rw-r--r-- | src/grp-initprogs/systemd-random-seed/random-seed.c | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/src/grp-initprogs/systemd-random-seed/random-seed.c b/src/grp-initprogs/systemd-random-seed/random-seed.c new file mode 100644 index 0000000000..83415ffb4c --- /dev/null +++ b/src/grp-initprogs/systemd-random-seed/random-seed.c @@ -0,0 +1,176 @@ +/*** + 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 <errno.h> +#include <fcntl.h> +#include <string.h> +#include <sys/stat.h> +#include <unistd.h> + +#include "systemd-basic/alloc-util.h" +#include "systemd-basic/fd-util.h" +#include "systemd-basic/io-util.h" +#include "systemd-basic/log.h" +#include "systemd-basic/mkdir.h" +#include "systemd-basic/string-util.h" +#include "systemd-basic/util.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, open_rw_error; + FILE *f; + bool refresh_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); + open_rw_error = -errno; + if (seed_fd < 0) { + refresh_seed_file = false; + + seed_fd = open(RANDOM_SEED, O_RDONLY|O_CLOEXEC|O_NOCTTY); + if (seed_fd < 0) { + bool missing = errno == ENOENT; + + log_full_errno(missing ? LOG_DEBUG : LOG_ERR, + open_rw_error, "Failed to open " RANDOM_SEED " for writing: %m"); + r = log_full_errno(missing ? LOG_DEBUG : LOG_ERR, + errno, "Failed to open " RANDOM_SEED " for reading: %m"); + if (missing) + r = 0; + + goto finish; + } + } + + 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) { + r = log_error_errno(errno, "Failed to open /dev/urandom: %m"); + goto finish; + } + } + + k = loop_read(seed_fd, buf, buf_size, false); + if (k < 0) + r = log_error_errno(k, "Failed to read seed from " RANDOM_SEED ": %m"); + else if (k == 0) { + r = 0; + log_debug("Seed file " RANDOM_SEED " not yet initialized, proceeding."); + } else { + (void) 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) { + r = log_error_errno(errno, "Failed to open " RANDOM_SEED ": %m"); + goto finish; + } + + random_fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY); + if (random_fd < 0) { + r = log_error_errno(errno, "Failed to open /dev/urandom: %m"); + goto finish; + } + + } else { + log_error("Unknown verb '%s'.", argv[1]); + r = -EINVAL; + goto finish; + } + + if (refresh_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. */ + (void) fchmod(seed_fd, 0600); + (void) fchown(seed_fd, 0, 0); + + k = loop_read(random_fd, buf, buf_size, false); + if (k < 0) { + r = log_error_errno(k, "Failed to read new seed from /dev/urandom: %m"); + goto finish; + } + if (k == 0) { + log_error("Got EOF while reading from /dev/urandom."); + r = -EIO; + goto finish; + } + + 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; +} |