--- /dev/null
+// SPDX-License-Identifier: (GPL-2.0 OR MIT OR Apache-2.0)
+/*
+ * Copyright (C) 2022 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+#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 <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>
+
+#define SEED_DIR "/etc/seedrng"
+#define CREDITABLE_SEED SEED_DIR "/seed.credit"
+#define NON_CREDITABLE_SEED SEED_DIR "/seed.no-credit"
+#define LOCK_FILE "/tmp/run/seedrng.lock"
+
+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) {
+ fprintf(stderr, "WARNING: Unable to determine pool size, falling back to %u bits: %s\n", 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;
+ } else if (ret < 0 && 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;
+ fprintf(stderr, "ERROR: Unable to open seed file: %s\n", strerror(errno));
+ return ret;
+ }
+ dfd = open(SEED_DIR, O_DIRECTORY | O_RDONLY);
+ if (dfd < 0) {
+ ret = -errno;
+ close(fd);
+ fprintf(stderr, "ERROR: Unable to open seed directory: %s\n", strerror(errno));
+ return ret;
+ }
+ seed_len = read(fd, seed, sizeof(seed));
+ if (seed_len < 0) {
+ ret = -errno;
+ fprintf(stderr, "ERROR: Unable to read seed file: %s\n", strerror(errno));
+ }
+ close(fd);
+ if (ret) {
+ close(dfd);
+ return ret;
+ }
+ if ((unlink(filename) < 0 || fsync(dfd) < 0) && seed_len) {
+ ret = -errno;
+ fprintf(stderr, "ERROR: Unable to remove seed after reading, so not seeding: %s\n", 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);
+
+ fprintf(stdout, "Seeding %zd bits %s crediting\n", seed_len * 8, credit ? "and" : "without");
+ ret = seed_rng(seed, seed_len, credit);
+ if (ret < 0)
+ fprintf(stderr, "ERROR: Unable to seed: %s\n", strerror(-ret));
+ return ret;
+}
+
+static bool skip_credit(void)
+{
+ const char *skip = getenv("SEEDRNG_SKIP_CREDIT");
+ return skip && (!strcmp(skip, "1") || !strcasecmp(skip, "true") ||
+ !strcasecmp(skip, "yes") || !strcasecmp(skip, "y"));
+}
+
+int main(int argc __attribute__((unused)), char *argv[] __attribute__((unused)))
+{
+ 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;
+
+ umask(0077);
+ if (getuid()) {
+ fprintf(stderr, "ERROR: This program requires root\n");
+ return 1;
+ }
+
+ 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) {
+ fprintf(stderr, "ERROR: Unable to create \"%s\" directory: %s\n", SEED_DIR, strerror(errno));
+ return 1;
+ }
+
+ lock = open(LOCK_FILE, O_WRONLY | O_CREAT, 0000);
+ if (lock < 0 || flock(lock, LOCK_EX) < 0) {
+ fprintf(stderr, "ERROR: Unable to open lock file: %s\n", 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) {
+ fprintf(stderr, "ERROR: Unable to read new seed: %s\n", 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);
+
+ fprintf(stdout, "Saving %zu bits of %s seed for next boot\n", 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) {
+ fprintf(stderr, "ERROR: Unable to open seed file for writing: %s\n", strerror(errno));
+ program_ret |= 1 << 4;
+ goto out;
+ }
+ if (write(fd, new_seed, new_seed_len) != (ssize_t)new_seed_len || fsync(fd) < 0) {
+ fprintf(stderr, "ERROR: Unable to write seed file: %s\n", strerror(errno));
+ program_ret |= 1 << 5;
+ goto out;
+ }
+ if (new_seed_creditable && rename(NON_CREDITABLE_SEED, CREDITABLE_SEED) < 0) {
+ fprintf(stderr, "WARNING: Unable to make new seed creditable: %s\n", strerror(errno));
+ program_ret |= 1 << 6;
+ }
+out:
+ if (fd >= 0)
+ close(fd);
+ if (lock >= 0)
+ close(lock);
+ return program_ret;
+}
projects / openwrt / staging / stintel.git / commitdiff