diff options
Diffstat (limited to 'src/rc/seedrng.c')
| -rw-r--r-- | src/rc/seedrng.c | 522 |
1 files changed, 0 insertions, 522 deletions
diff --git a/src/rc/seedrng.c b/src/rc/seedrng.c deleted file mode 100644 index 95fb947d..00000000 --- a/src/rc/seedrng.c +++ /dev/null @@ -1,522 +0,0 @@ -/* - * seedrng.c - * Seed kernel RNG from seed file, based on code from: - * https://git.zx2c4.com/seedrng/about/ - */ - -/* - * Copyright (c) 2022 The OpenRC Authors. - * See the Authors file at the top-level directory of this distribution and - * https://github.com/OpenRC/openrc/blob/HEAD/AUTHORS - * - * This file is part of OpenRC. It is subject to the license terms in - * the LICENSE file found in the top-level directory of this - * distribution and at https://github.com/OpenRC/openrc/blob/HEAD/LICENSE - * This file may not be copied, modified, propagated, or distributed - * except according to the terms contained in the LICENSE file. - */ - -#include <linux/random.h> -#include <sys/random.h> -#include <sys/ioctl.h> -#include <sys/file.h> -#include <sys/stat.h> -#include <sys/types.h> -#include <fcntl.h> -#include <getopt.h> -#include <poll.h> -#include <unistd.h> -#include <time.h> -#include <errno.h> -#include <endian.h> -#include <stdbool.h> -#include <stdint.h> -#include <string.h> -#include <stdio.h> -#include <stdlib.h> - -#include "rc.h" -#include "einfo.h" -#include "helpers.h" -#include "_usage.h" - -#ifndef GRND_INSECURE -#define GRND_INSECURE 0x0004 /* Apparently some headers don't ship with this yet. */ -#endif - -/* Use long option value that is out of range for 8 bit getopt values. - * The exact enum value is internal and can freely change, so we keep the - * options sorted. - */ -enum long_opts { - /* This has to come first so following values stay in the 0x100+ range. */ - LONGOPT_BASE = 0x100, - LONGOPT_LOCK_FILE, - LONGOPT_SEED_DIR, - LONGOPT_SKIP_CREDIT, -}; - -const char *applet = NULL; -const char *extraopts =NULL; -const char getoptstring[] = getoptstring_COMMON; -const struct option longopts[] = { - { "lock-file", 1, NULL, LONGOPT_LOCK_FILE }, - { "seed-dir", 1, NULL, LONGOPT_SEED_DIR }, - { "skip-credit", 0, NULL, LONGOPT_SKIP_CREDIT }, - longopts_COMMON -}; -const char * const longopts_help[] = { - "lock file", - "directory for seed files", - "skip credit", - longopts_help_COMMON -}; -const char *usagestring = NULL; - -static char *lock_file = NULL; -static char *seed_dir = NULL; -static char *creditable_seed = NULL; -static char *non_creditable_seed = NULL; - -enum blake2s_lengths { - BLAKE2S_BLOCK_LEN = 64, - BLAKE2S_HASH_LEN = 32, - BLAKE2S_KEY_LEN = 32 -}; - -enum seedrng_lengths { - MAX_SEED_LEN = 512, - MIN_SEED_LEN = BLAKE2S_HASH_LEN -}; - -struct blake2s_state { - uint32_t h[8]; - uint32_t t[2]; - uint32_t f[2]; - uint8_t buf[BLAKE2S_BLOCK_LEN]; - unsigned int buflen; - unsigned int outlen; -}; - -#define le32_to_cpup(a) le32toh(*(a)) -#define cpu_to_le32(a) htole32(a) -#ifndef ARRAY_SIZE -#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) -#endif -#ifndef DIV_ROUND_UP -#define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d)) -#endif - -static inline void cpu_to_le32_array(uint32_t *buf, unsigned int words) -{ - while (words--) { - *buf = cpu_to_le32(*buf); - ++buf; - } -} - -static inline void le32_to_cpu_array(uint32_t *buf, unsigned int words) -{ - while (words--) { - *buf = le32_to_cpup(buf); - ++buf; - } -} - -static inline uint32_t ror32(uint32_t word, unsigned int shift) -{ - return (word >> (shift & 31)) | (word << ((-shift) & 31)); -} - -static const uint32_t blake2s_iv[8] = { - 0x6A09E667UL, 0xBB67AE85UL, 0x3C6EF372UL, 0xA54FF53AUL, - 0x510E527FUL, 0x9B05688CUL, 0x1F83D9ABUL, 0x5BE0CD19UL -}; - -static const uint8_t blake2s_sigma[10][16] = { - { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 }, - { 14, 10, 4, 8, 9, 15, 13, 6, 1, 12, 0, 2, 11, 7, 5, 3 }, - { 11, 8, 12, 0, 5, 2, 15, 13, 10, 14, 3, 6, 7, 1, 9, 4 }, - { 7, 9, 3, 1, 13, 12, 11, 14, 2, 6, 5, 10, 4, 0, 15, 8 }, - { 9, 0, 5, 7, 2, 4, 10, 15, 14, 1, 11, 12, 6, 8, 3, 13 }, - { 2, 12, 6, 10, 0, 11, 8, 3, 4, 13, 7, 5, 15, 14, 1, 9 }, - { 12, 5, 1, 15, 14, 13, 4, 10, 0, 7, 6, 3, 9, 2, 8, 11 }, - { 13, 11, 7, 14, 12, 1, 3, 9, 5, 0, 15, 4, 8, 6, 2, 10 }, - { 6, 15, 14, 9, 11, 3, 0, 8, 12, 2, 13, 7, 1, 4, 10, 5 }, - { 10, 2, 8, 4, 7, 6, 1, 5, 15, 11, 9, 14, 3, 12, 13, 0 }, -}; - -static void blake2s_set_lastblock(struct blake2s_state *state) -{ - state->f[0] = -1; -} - -static void blake2s_increment_counter(struct blake2s_state *state, const uint32_t inc) -{ - state->t[0] += inc; - state->t[1] += (state->t[0] < inc); -} - -static void blake2s_init_param(struct blake2s_state *state, const uint32_t param) -{ - int i; - - memset(state, 0, sizeof(*state)); - for (i = 0; i < 8; ++i) - state->h[i] = blake2s_iv[i]; - state->h[0] ^= param; -} - -static void blake2s_init(struct blake2s_state *state, const size_t outlen) -{ - blake2s_init_param(state, 0x01010000 | outlen); - state->outlen = outlen; -} - -static void blake2s_compress(struct blake2s_state *state, const uint8_t *block, size_t nblocks, const uint32_t inc) -{ - uint32_t m[16]; - uint32_t v[16]; - int i; - - while (nblocks > 0) { - blake2s_increment_counter(state, inc); - memcpy(m, block, BLAKE2S_BLOCK_LEN); - le32_to_cpu_array(m, ARRAY_SIZE(m)); - memcpy(v, state->h, 32); - v[ 8] = blake2s_iv[0]; - v[ 9] = blake2s_iv[1]; - v[10] = blake2s_iv[2]; - v[11] = blake2s_iv[3]; - v[12] = blake2s_iv[4] ^ state->t[0]; - v[13] = blake2s_iv[5] ^ state->t[1]; - v[14] = blake2s_iv[6] ^ state->f[0]; - v[15] = blake2s_iv[7] ^ state->f[1]; - -#define G(r, i, a, b, c, d) do { \ - a += b + m[blake2s_sigma[r][2 * i + 0]]; \ - d = ror32(d ^ a, 16); \ - c += d; \ - b = ror32(b ^ c, 12); \ - a += b + m[blake2s_sigma[r][2 * i + 1]]; \ - d = ror32(d ^ a, 8); \ - c += d; \ - b = ror32(b ^ c, 7); \ -} while (0) - -#define ROUND(r) do { \ - G(r, 0, v[0], v[ 4], v[ 8], v[12]); \ - G(r, 1, v[1], v[ 5], v[ 9], v[13]); \ - G(r, 2, v[2], v[ 6], v[10], v[14]); \ - G(r, 3, v[3], v[ 7], v[11], v[15]); \ - G(r, 4, v[0], v[ 5], v[10], v[15]); \ - G(r, 5, v[1], v[ 6], v[11], v[12]); \ - G(r, 6, v[2], v[ 7], v[ 8], v[13]); \ - G(r, 7, v[3], v[ 4], v[ 9], v[14]); \ -} while (0) - ROUND(0); - ROUND(1); - ROUND(2); - ROUND(3); - ROUND(4); - ROUND(5); - ROUND(6); - ROUND(7); - ROUND(8); - ROUND(9); - -#undef G -#undef ROUND - - for (i = 0; i < 8; ++i) - state->h[i] ^= v[i] ^ v[i + 8]; - - block += BLAKE2S_BLOCK_LEN; - --nblocks; - } -} - -static void blake2s_update(struct blake2s_state *state, const void *inp, size_t inlen) -{ - const size_t fill = BLAKE2S_BLOCK_LEN - state->buflen; - const uint8_t *in = inp; - - if (!inlen) - return; - if (inlen > fill) { - memcpy(state->buf + state->buflen, in, fill); - blake2s_compress(state, state->buf, 1, BLAKE2S_BLOCK_LEN); - state->buflen = 0; - in += fill; - inlen -= fill; - } - if (inlen > BLAKE2S_BLOCK_LEN) { - const size_t nblocks = DIV_ROUND_UP(inlen, BLAKE2S_BLOCK_LEN); - blake2s_compress(state, in, nblocks - 1, BLAKE2S_BLOCK_LEN); - in += BLAKE2S_BLOCK_LEN * (nblocks - 1); - inlen -= BLAKE2S_BLOCK_LEN * (nblocks - 1); - } - memcpy(state->buf + state->buflen, in, inlen); - state->buflen += inlen; -} - -static void blake2s_final(struct blake2s_state *state, uint8_t *out) -{ - blake2s_set_lastblock(state); - memset(state->buf + state->buflen, 0, BLAKE2S_BLOCK_LEN - state->buflen); - blake2s_compress(state, state->buf, 1, state->buflen); - cpu_to_le32_array(state->h, ARRAY_SIZE(state->h)); - memcpy(out, state->h, state->outlen); -} - -static size_t determine_optimal_seed_len(void) -{ - size_t ret = 0; - char poolsize_str[11] = { 0 }; - int fd = open("/proc/sys/kernel/random/poolsize", O_RDONLY); - - if (fd < 0 || read(fd, poolsize_str, sizeof(poolsize_str) - 1) < 0) { - ewarn("%s: Unable to determine pool size, falling back to %u bits: %s", - applet, MIN_SEED_LEN * 8, strerror(errno)); - ret = MIN_SEED_LEN; - } else - ret = DIV_ROUND_UP(strtoul(poolsize_str, NULL, 10), 8); - if (fd >= 0) - close(fd); - if (ret < MIN_SEED_LEN) - ret = MIN_SEED_LEN; - else if (ret > MAX_SEED_LEN) - ret = MAX_SEED_LEN; - return ret; -} - -static int read_new_seed(uint8_t *seed, size_t len, bool *is_creditable) -{ - ssize_t ret; - int urandom_fd; - - *is_creditable = false; - ret = getrandom(seed, len, GRND_NONBLOCK); - if (ret == (ssize_t)len) { - *is_creditable = true; - return 0; - } - if (ret == -1 && errno == ENOSYS) { - struct pollfd random_fd = { - .fd = open("/dev/random", O_RDONLY), - .events = POLLIN - }; - if (random_fd.fd < 0) - return -errno; - *is_creditable = poll(&random_fd, 1, 0) == 1; - close(random_fd.fd); - } else if (getrandom(seed, len, GRND_INSECURE) == (ssize_t)len) - return 0; - urandom_fd = open("/dev/urandom", O_RDONLY); - if (urandom_fd < 0) - return -errno; - ret = read(urandom_fd, seed, len); - if (ret == (ssize_t)len) - ret = 0; - else - ret = -errno ? -errno : -EIO; - close(urandom_fd); - return ret; -} - -static int seed_rng(uint8_t *seed, size_t len, bool credit) -{ - struct { - int entropy_count; - int buf_size; - uint8_t buffer[MAX_SEED_LEN]; - } req = { - .entropy_count = credit ? len * 8 : 0, - .buf_size = len - }; - int random_fd, ret; - - if (len > sizeof(req.buffer)) - return -EFBIG; - memcpy(req.buffer, seed, len); - - random_fd = open("/dev/random", O_RDWR); - if (random_fd < 0) - return -errno; - ret = ioctl(random_fd, RNDADDENTROPY, &req); - if (ret) - ret = -errno ? -errno : -EIO; - close(random_fd); - return ret; -} - -static int seed_from_file_if_exists(const char *filename, bool credit, struct blake2s_state *hash) -{ - uint8_t seed[MAX_SEED_LEN]; - ssize_t seed_len; - int fd, dfd, ret = 0; - - fd = open(filename, O_RDONLY); - if (fd < 0 && errno == ENOENT) - return 0; - else if (fd < 0) { - ret = -errno; - eerror("%s: Unable to open seed file: %s", applet, strerror(errno)); - return ret; - } - dfd = open(seed_dir, O_DIRECTORY | O_RDONLY); - if (dfd < 0) { - ret = -errno; - close(fd); - eerror("%s: Unable to open seed directory: %s", applet, strerror(errno)); - return ret; - } - seed_len = read(fd, seed, sizeof(seed)); - if (seed_len < 0) { - ret = -errno; - eerror("%s: Unable to read seed file: %s", applet, strerror(errno)); - } - close(fd); - if (ret) { - close(dfd); - return ret; - } - if ((unlink(filename) < 0 || fsync(dfd) < 0) && seed_len) { - ret = -errno; - eerror("%s: Unable to remove seed after reading, so not seeding: %s", - applet, strerror(errno)); - } - close(dfd); - if (ret) - return ret; - if (!seed_len) - return 0; - - blake2s_update(hash, &seed_len, sizeof(seed_len)); - blake2s_update(hash, seed, seed_len); - - einfo("Seeding %zd bits %s crediting", seed_len * 8, credit ? "and" : "without"); - ret = seed_rng(seed, seed_len, credit); - if (ret < 0) - eerror("%s: Unable to seed: %s", applet, strerror(-ret)); - return ret; -} - -static void populate_global_paths(void) -{ - if (!lock_file) - lock_file = xstrdup("/var/run/seedrng.lock"); - if (!seed_dir) - seed_dir = xstrdup("/var/lib/seedrng"); - xasprintf(&creditable_seed, "%s/seed.credit", seed_dir); - xasprintf(&non_creditable_seed, "%s/seed.no-credit", seed_dir); -} - -static void cleanup(void) -{ - free(lock_file); - free(seed_dir); - free(creditable_seed); - free(non_creditable_seed); -} - -int main(int argc, char **argv) -{ - int opt; - static const char seedrng_prefix[] = "SeedRNG v1 Old+New Prefix"; - static const char seedrng_failure[] = "SeedRNG v1 No New Seed Failure"; - int ret, fd = -1, lock, program_ret = 0; - uint8_t new_seed[MAX_SEED_LEN]; - size_t new_seed_len; - bool new_seed_creditable; - struct timespec realtime = { 0 }, boottime = { 0 }; - struct blake2s_state hash; - bool skip_credit = false; - - atexit(cleanup); - applet = basename_c(argv[0]); - if (geteuid()) - eerrorx("%s: superuser access is required", applet); - umask(0077); - - while ((opt = getopt_long(argc, argv, getoptstring, - longopts, (int *) 0)) != -1) - { - switch (opt) { - case LONGOPT_LOCK_FILE: - if (!lock_file) - lock_file = xstrdup(optarg); - break; - case LONGOPT_SEED_DIR: - if (!seed_dir) - seed_dir = xstrdup(optarg); - break; - case LONGOPT_SKIP_CREDIT: - skip_credit = true; - break; - case_RC_COMMON_GETOPT - } - } - populate_global_paths(); - blake2s_init(&hash, BLAKE2S_HASH_LEN); - blake2s_update(&hash, seedrng_prefix, strlen(seedrng_prefix)); - clock_gettime(CLOCK_REALTIME, &realtime); - clock_gettime(CLOCK_BOOTTIME, &boottime); - blake2s_update(&hash, &realtime, sizeof(realtime)); - blake2s_update(&hash, &boottime, sizeof(boottime)); - - if (mkdir(seed_dir, 0700) < 0 && errno != EEXIST) - eerrorx("%s: Unable to create \"%s\" directory: %s", - applet, seed_dir, strerror(errno)); - - lock = open(lock_file, O_WRONLY | O_CREAT, 0000); - if (lock < 0 || flock(lock, LOCK_EX) < 0) { - eerror("%s: Unable to open lock file: %s", applet, strerror(errno)); - program_ret = 1; - goto out; - } - - ret = seed_from_file_if_exists(non_creditable_seed, false, &hash); - if (ret < 0) - program_ret |= 1 << 1; - ret = seed_from_file_if_exists(creditable_seed, !skip_credit, &hash); - if (ret < 0) - program_ret |= 1 << 2; - - new_seed_len = determine_optimal_seed_len(); - ret = read_new_seed(new_seed, new_seed_len, &new_seed_creditable); - if (ret < 0) { - eerror("%s: Unable to read new seed: %s", applet, strerror(-ret)); - new_seed_len = BLAKE2S_HASH_LEN; - strncpy((char *)new_seed, seedrng_failure, new_seed_len); - program_ret |= 1 << 3; - } - blake2s_update(&hash, &new_seed_len, sizeof(new_seed_len)); - blake2s_update(&hash, new_seed, new_seed_len); - blake2s_final(&hash, new_seed + new_seed_len - BLAKE2S_HASH_LEN); - - einfo("Saving %zu bits of %s seed for next boot", new_seed_len * 8, new_seed_creditable ? "creditable" : "non-creditable"); - fd = open(non_creditable_seed, O_WRONLY | O_CREAT | O_TRUNC, 0400); - if (fd < 0) { - eerror("%s: Unable to open seed file for writing: %s", - applet, strerror(errno)); - program_ret |= 1 << 4; - goto out; - } - if (write(fd, new_seed, new_seed_len) != (ssize_t)new_seed_len || fsync(fd) < 0) { - eerror("%s: Unable to write seed file: %s", applet, strerror(errno)); - program_ret |= 1 << 5; - goto out; - } - if (new_seed_creditable && rename(non_creditable_seed, creditable_seed) < 0) { - ewarn("%s: Unable to make new seed creditable: %s", - applet, strerror(errno)); - program_ret |= 1 << 6; - } -out: - if (fd >= 0) - close(fd); - if (lock >= 0) - close(lock); - return program_ret; -} |