seedrng: use libbb functions
- Make extensive use of libbb.h functions, which simplify a lot of code and reduce binary size considerably. - Use the already existing PID_FILE_PATH variable. function old new delta seed_from_file_if_exists 697 533 -164 .rodata 108665 108484 -181 seedrng_main 1463 1218 -245 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-590) Total: -590 bytes text data bss dec hex filename 977035 4227 1848 983110 f0046 busybox_old 976445 4227 1848 982520 efdf8 busybox_unstripped Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
This commit is contained in:
Jason A. Donenfeld
Bernhard Reutner-Fischer
parent
4b407bacd4
commit
4538578996
@ -6,7 +6,7 @@
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*/
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//config:config SEEDRNG
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//config: bool "seedrng (3.8 kb)"
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//config: bool "seedrng (2.6 kb)"
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//config: default y
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//config: help
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//config: Seed the kernel RNG from seed files, meant to be called
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@ -50,53 +50,38 @@
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#define GRND_INSECURE 0x0004 /* Apparently some headers don't ship with this yet. */
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#endif
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#ifndef LOCALSTATEDIR
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#define LOCALSTATEDIR "/var/lib"
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#endif
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#ifndef RUNSTATEDIR
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#define RUNSTATEDIR "/var/run"
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#if ENABLE_PID_FILE_PATH
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#define PID_FILE_PATH CONFIG_PID_FILE_PATH
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#else
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#define PID_FILE_PATH "/var/run"
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#endif
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#define DEFAULT_SEED_DIR LOCALSTATEDIR "/seedrng"
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#define DEFAULT_LOCK_FILE RUNSTATEDIR "/seedrng.lock"
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#define DEFAULT_SEED_DIR "/var/lib/seedrng"
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#define DEFAULT_LOCK_FILE PID_FILE_PATH "/seedrng.lock"
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#define CREDITABLE_SEED_NAME "seed.credit"
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#define NON_CREDITABLE_SEED_NAME "seed.no-credit"
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static char *seed_dir, *lock_file, *creditable_seed, *non_creditable_seed;
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enum seedrng_lengths {
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MAX_SEED_LEN = 512,
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MIN_SEED_LEN = SHA256_OUTSIZE
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MIN_SEED_LEN = SHA256_OUTSIZE,
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MAX_SEED_LEN = 512
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};
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#ifndef DIV_ROUND_UP
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#define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
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#endif
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static size_t determine_optimal_seed_len(void)
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{
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size_t ret = 0;
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char poolsize_str[11] = { 0 };
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int fd = open("/proc/sys/kernel/random/poolsize", O_RDONLY);
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if (fd < 0 || read(fd, poolsize_str, sizeof(poolsize_str) - 1) < 0) {
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fprintf(stderr, "WARNING: Unable to determine pool size, falling back to %u bits: %s\n", MIN_SEED_LEN * 8, strerror(errno));
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ret = MIN_SEED_LEN;
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} else
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ret = DIV_ROUND_UP(strtoul(poolsize_str, NULL, 10), 8);
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if (fd >= 0)
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close(fd);
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if (ret < MIN_SEED_LEN)
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ret = MIN_SEED_LEN;
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else if (ret > MAX_SEED_LEN)
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ret = MAX_SEED_LEN;
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return ret;
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if (open_read_close("/proc/sys/kernel/random/poolsize", poolsize_str, sizeof(poolsize_str) - 1) < 0) {
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bb_perror_msg("unable to determine pool size, falling back to %u bits", MIN_SEED_LEN * 8);
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return MIN_SEED_LEN;
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}
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return MAX(MIN((bb_strtoul(poolsize_str, NULL, 10) + 7) / 8, MAX_SEED_LEN), MIN_SEED_LEN);
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}
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static int read_new_seed(uint8_t *seed, size_t len, bool *is_creditable)
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{
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ssize_t ret;
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int urandom_fd;
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*is_creditable = false;
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ret = getrandom(seed, len, GRND_NONBLOCK);
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@ -109,21 +94,16 @@ static int read_new_seed(uint8_t *seed, size_t len, bool *is_creditable)
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.events = POLLIN
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};
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if (random_fd.fd < 0)
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return -errno;
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*is_creditable = poll(&random_fd, 1, 0) == 1;
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return -1;
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*is_creditable = safe_poll(&random_fd, 1, 0) == 1;
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close(random_fd.fd);
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} else if (getrandom(seed, len, GRND_INSECURE) == (ssize_t)len)
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return 0;
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urandom_fd = open("/dev/urandom", O_RDONLY);
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if (urandom_fd < 0)
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return -errno;
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ret = read(urandom_fd, seed, len);
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if (ret == (ssize_t)len)
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ret = 0;
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else
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ret = -errno ? -errno : -EIO;
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close(urandom_fd);
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return ret;
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if (open_read_close("/dev/urandom", seed, len) == (ssize_t)len)
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return 0;
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if (!errno)
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errno = EIO;
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return -1;
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}
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static int seed_rng(uint8_t *seed, size_t len, bool credit)
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@ -138,69 +118,63 @@ static int seed_rng(uint8_t *seed, size_t len, bool credit)
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};
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int random_fd, ret;
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if (len > sizeof(req.buffer))
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return -EFBIG;
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if (len > sizeof(req.buffer)) {
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errno = EFBIG;
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return -1;
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}
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memcpy(req.buffer, seed, len);
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random_fd = open("/dev/random", O_RDWR);
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if (random_fd < 0)
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return -errno;
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return -1;
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ret = ioctl(random_fd, RNDADDENTROPY, &req);
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if (ret)
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ret = -errno ? -errno : -EIO;
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close(random_fd);
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return ret;
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errno = -ret;
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return ret ? -1 : 0;
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}
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static int seed_from_file_if_exists(const char *filename, bool credit, sha256_ctx_t *hash)
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{
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uint8_t seed[MAX_SEED_LEN];
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ssize_t seed_len;
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int fd, dfd, ret = 0;
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int dfd = -1, ret = 0;
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fd = open(filename, O_RDONLY);
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if (fd < 0 && errno == ENOENT)
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return 0;
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else if (fd < 0) {
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ret = -errno;
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fprintf(stderr, "ERROR: Unable to open seed file: %s\n", strerror(errno));
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return ret;
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}
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dfd = open(seed_dir, O_DIRECTORY | O_RDONLY);
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if (dfd < 0) {
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ret = -errno;
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close(fd);
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fprintf(stderr, "ERROR: Unable to open seed directory: %s\n", strerror(errno));
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return ret;
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bb_simple_perror_msg("unable to open seed directory");
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goto out;
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}
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seed_len = read(fd, seed, sizeof(seed));
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seed_len = open_read_close(filename, seed, sizeof(seed));
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if (seed_len < 0) {
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if (errno != ENOENT) {
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ret = -errno;
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fprintf(stderr, "ERROR: Unable to read seed file: %s\n", strerror(errno));
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bb_simple_perror_msg("unable to read seed file");
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}
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close(fd);
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if (ret) {
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close(dfd);
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return ret;
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goto out;
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}
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if ((unlink(filename) < 0 || fsync(dfd) < 0) && seed_len) {
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ret = -errno;
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fprintf(stderr, "ERROR: Unable to remove seed after reading, so not seeding: %s\n", strerror(errno));
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bb_simple_perror_msg("unable to remove seed after reading, so not seeding");
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goto out;
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}
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close(dfd);
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if (ret)
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return ret;
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if (!seed_len)
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return 0;
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goto out;
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sha256_hash(hash, &seed_len, sizeof(seed_len));
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sha256_hash(hash, seed, seed_len);
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fprintf(stdout, "Seeding %zd bits %s crediting\n", seed_len * 8, credit ? "and" : "without");
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printf("Seeding %zd bits %s crediting\n", seed_len * 8, credit ? "and" : "without");
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ret = seed_rng(seed, seed_len, credit);
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if (ret < 0)
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fprintf(stderr, "ERROR: Unable to seed: %s\n", strerror(-ret));
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return ret;
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bb_simple_perror_msg("unable to seed");
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out:
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if (dfd >= 0)
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close(dfd);
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errno = -ret;
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return ret ? -1 : 0;
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}
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int seedrng_main(int argc, char *argv[]) MAIN_EXTERNALLY_VISIBLE;
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@ -236,14 +210,12 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[])
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if (!(opt & OPT_l) || !lock_file)
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lock_file = xstrdup(DEFAULT_LOCK_FILE);
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skip_credit = opt & OPT_n;
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creditable_seed = xasprintf("%s/%s", seed_dir, CREDITABLE_SEED_NAME);
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non_creditable_seed = xasprintf("%s/%s", seed_dir, NON_CREDITABLE_SEED_NAME);
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creditable_seed = concat_path_file(seed_dir, CREDITABLE_SEED_NAME);
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non_creditable_seed = concat_path_file(seed_dir, NON_CREDITABLE_SEED_NAME);
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umask(0077);
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if (getuid()) {
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fprintf(stderr, "ERROR: This program requires root\n");
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return 1;
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}
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if (getuid())
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bb_simple_error_msg_and_die("this program requires root");
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sha256_begin(&hash);
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sha256_hash(&hash, seedrng_prefix, strlen(seedrng_prefix));
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@ -252,14 +224,12 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[])
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sha256_hash(&hash, &realtime, sizeof(realtime));
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sha256_hash(&hash, &boottime, sizeof(boottime));
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if (mkdir(seed_dir, 0700) < 0 && errno != EEXIST) {
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fprintf(stderr, "ERROR: Unable to create \"%s\" directory: %s\n", seed_dir, strerror(errno));
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return 1;
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}
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if (mkdir(seed_dir, 0700) < 0 && errno != EEXIST)
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bb_simple_perror_msg_and_die("unable to create seed directory");
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lock = open(lock_file, O_WRONLY | O_CREAT, 0000);
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if (lock < 0 || flock(lock, LOCK_EX) < 0) {
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fprintf(stderr, "ERROR: Unable to open lock file: %s\n", strerror(errno));
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bb_simple_perror_msg("unable to open lock file");
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program_ret = 1;
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goto out;
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}
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@ -274,7 +244,7 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[])
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new_seed_len = determine_optimal_seed_len();
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ret = read_new_seed(new_seed, new_seed_len, &new_seed_creditable);
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if (ret < 0) {
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fprintf(stderr, "ERROR: Unable to read new seed: %s\n", strerror(-ret));
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bb_simple_perror_msg("unable to read new seed");
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new_seed_len = SHA256_OUTSIZE;
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strncpy((char *)new_seed, seedrng_failure, new_seed_len);
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program_ret |= 1 << 3;
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@ -283,20 +253,20 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[])
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sha256_hash(&hash, new_seed, new_seed_len);
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sha256_end(&hash, new_seed + new_seed_len - SHA256_OUTSIZE);
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fprintf(stdout, "Saving %zu bits of %s seed for next boot\n", new_seed_len * 8, new_seed_creditable ? "creditable" : "non-creditable");
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printf("Saving %zu bits of %s seed for next boot\n", new_seed_len * 8, new_seed_creditable ? "creditable" : "non-creditable");
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fd = open(non_creditable_seed, O_WRONLY | O_CREAT | O_TRUNC, 0400);
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if (fd < 0) {
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fprintf(stderr, "ERROR: Unable to open seed file for writing: %s\n", strerror(errno));
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bb_simple_perror_msg("unable to open seed file for writing");
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program_ret |= 1 << 4;
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goto out;
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}
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if (write(fd, new_seed, new_seed_len) != (ssize_t)new_seed_len || fsync(fd) < 0) {
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fprintf(stderr, "ERROR: Unable to write seed file: %s\n", strerror(errno));
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bb_simple_perror_msg("unable to write seed file");
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program_ret |= 1 << 5;
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goto out;
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}
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if (new_seed_creditable && rename(non_creditable_seed, creditable_seed) < 0) {
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fprintf(stderr, "WARNING: Unable to make new seed creditable: %s\n", strerror(errno));
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bb_simple_perror_msg("unable to make new seed creditable");
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program_ret |= 1 << 6;
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}
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out:
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