63a5ee3d8c
`seed_dir` gets allocated via xstrdup but never gets freed - which clang-tidy flags as a memory leak. instead of free-ing the allocation, just don't allocate to begin with since there's no need for it. also bump the copyright year.
533 lines
14 KiB
C
533 lines
14 KiB
C
/*
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* seedrng.c
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* Seed kernel RNG from seed file, based on code from:
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* https://git.zx2c4.com/seedrng/about/
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*/
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/*
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* Copyright (c) 2023 The OpenRC Authors.
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* See the Authors file at the top-level directory of this distribution and
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* https://github.com/OpenRC/openrc/blob/HEAD/AUTHORS
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*
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* This file is part of OpenRC. It is subject to the license terms in
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* the LICENSE file found in the top-level directory of this
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* distribution and at https://github.com/OpenRC/openrc/blob/HEAD/LICENSE
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* This file may not be copied, modified, propagated, or distributed
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* except according to the terms contained in the LICENSE file.
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*/
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#include <linux/random.h>
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#include <sys/random.h>
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#include <sys/ioctl.h>
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#include <sys/file.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <fcntl.h>
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#include <getopt.h>
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#include <poll.h>
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#include <unistd.h>
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#include <time.h>
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#include <errno.h>
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#include <endian.h>
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <string.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "einfo.h"
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#include "helpers.h"
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#include "_usage.h"
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#ifndef GRND_INSECURE
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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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#define DEFAULT_SEED_DIR "/var/lib/seedrng"
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#define CREDITABLE_SEED "seed.credit"
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#define NON_CREDITABLE_SEED "seed.no-credit"
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/* Use long option value that is out of range for 8 bit getopt values.
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* The exact enum value is internal and can freely change, so we keep the
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* options sorted.
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*/
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enum long_opts {
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/* This has to come first so following values stay in the 0x100+ range. */
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LONGOPT_BASE = 0x100,
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LONGOPT_SEED_DIR,
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LONGOPT_SKIP_CREDIT,
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};
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const char *applet = NULL;
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const char *extraopts = NULL;
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const char getoptstring[] = getoptstring_COMMON;
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const struct option longopts[] = {
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{ "seed-dir", 1, NULL, LONGOPT_SEED_DIR },
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{ "skip-credit", 0, NULL, LONGOPT_SKIP_CREDIT },
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longopts_COMMON
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};
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const char * const longopts_help[] = {
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"Directory for seed files (default: " DEFAULT_SEED_DIR ")",
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"Skip crediting entropy of seeds",
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longopts_help_COMMON
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};
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const char *usagestring = NULL;
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enum blake2s_lengths {
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BLAKE2S_BLOCK_LEN = 64,
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BLAKE2S_HASH_LEN = 32,
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BLAKE2S_KEY_LEN = 32
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};
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enum seedrng_lengths {
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MAX_SEED_LEN = 512,
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MIN_SEED_LEN = BLAKE2S_HASH_LEN
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};
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struct blake2s_state {
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uint32_t h[8];
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uint32_t t[2];
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uint32_t f[2];
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uint8_t buf[BLAKE2S_BLOCK_LEN];
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unsigned int buflen;
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unsigned int outlen;
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};
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#define le32_to_cpup(a) le32toh(*(a))
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#define cpu_to_le32(a) htole32(a)
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#ifndef ARRAY_SIZE
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#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
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#endif
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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 inline void cpu_to_le32_array(uint32_t *buf, unsigned int words)
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{
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while (words--) {
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*buf = cpu_to_le32(*buf);
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++buf;
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}
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}
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static inline void le32_to_cpu_array(uint32_t *buf, unsigned int words)
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{
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while (words--) {
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*buf = le32_to_cpup(buf);
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++buf;
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}
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}
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static inline uint32_t ror32(uint32_t word, unsigned int shift)
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{
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return (word >> (shift & 31)) | (word << ((-shift) & 31));
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}
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static const uint32_t blake2s_iv[8] = {
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0x6A09E667UL, 0xBB67AE85UL, 0x3C6EF372UL, 0xA54FF53AUL,
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0x510E527FUL, 0x9B05688CUL, 0x1F83D9ABUL, 0x5BE0CD19UL
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};
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static const uint8_t blake2s_sigma[10][16] = {
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{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 },
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{ 14, 10, 4, 8, 9, 15, 13, 6, 1, 12, 0, 2, 11, 7, 5, 3 },
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{ 11, 8, 12, 0, 5, 2, 15, 13, 10, 14, 3, 6, 7, 1, 9, 4 },
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{ 7, 9, 3, 1, 13, 12, 11, 14, 2, 6, 5, 10, 4, 0, 15, 8 },
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{ 9, 0, 5, 7, 2, 4, 10, 15, 14, 1, 11, 12, 6, 8, 3, 13 },
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{ 2, 12, 6, 10, 0, 11, 8, 3, 4, 13, 7, 5, 15, 14, 1, 9 },
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{ 12, 5, 1, 15, 14, 13, 4, 10, 0, 7, 6, 3, 9, 2, 8, 11 },
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{ 13, 11, 7, 14, 12, 1, 3, 9, 5, 0, 15, 4, 8, 6, 2, 10 },
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{ 6, 15, 14, 9, 11, 3, 0, 8, 12, 2, 13, 7, 1, 4, 10, 5 },
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{ 10, 2, 8, 4, 7, 6, 1, 5, 15, 11, 9, 14, 3, 12, 13, 0 },
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};
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static void blake2s_set_lastblock(struct blake2s_state *state)
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{
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state->f[0] = -1;
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}
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static void blake2s_increment_counter(struct blake2s_state *state, const uint32_t inc)
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{
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state->t[0] += inc;
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state->t[1] += (state->t[0] < inc);
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}
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static void blake2s_init_param(struct blake2s_state *state, const uint32_t param)
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{
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int i;
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memset(state, 0, sizeof(*state));
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for (i = 0; i < 8; ++i)
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state->h[i] = blake2s_iv[i];
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state->h[0] ^= param;
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}
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static void blake2s_init(struct blake2s_state *state, const size_t outlen)
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{
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blake2s_init_param(state, 0x01010000 | outlen);
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state->outlen = outlen;
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}
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static void blake2s_compress(struct blake2s_state *state, const uint8_t *block, size_t nblocks, const uint32_t inc)
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{
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uint32_t m[16];
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uint32_t v[16];
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int i;
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while (nblocks > 0) {
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blake2s_increment_counter(state, inc);
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memcpy(m, block, BLAKE2S_BLOCK_LEN);
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le32_to_cpu_array(m, ARRAY_SIZE(m));
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memcpy(v, state->h, 32);
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v[ 8] = blake2s_iv[0];
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v[ 9] = blake2s_iv[1];
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v[10] = blake2s_iv[2];
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v[11] = blake2s_iv[3];
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v[12] = blake2s_iv[4] ^ state->t[0];
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v[13] = blake2s_iv[5] ^ state->t[1];
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v[14] = blake2s_iv[6] ^ state->f[0];
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v[15] = blake2s_iv[7] ^ state->f[1];
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#define G(r, i, a, b, c, d) do { \
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a += b + m[blake2s_sigma[r][2 * i + 0]]; \
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d = ror32(d ^ a, 16); \
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c += d; \
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b = ror32(b ^ c, 12); \
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a += b + m[blake2s_sigma[r][2 * i + 1]]; \
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d = ror32(d ^ a, 8); \
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c += d; \
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b = ror32(b ^ c, 7); \
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} while (0)
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#define ROUND(r) do { \
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G(r, 0, v[0], v[ 4], v[ 8], v[12]); \
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G(r, 1, v[1], v[ 5], v[ 9], v[13]); \
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G(r, 2, v[2], v[ 6], v[10], v[14]); \
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G(r, 3, v[3], v[ 7], v[11], v[15]); \
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G(r, 4, v[0], v[ 5], v[10], v[15]); \
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G(r, 5, v[1], v[ 6], v[11], v[12]); \
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G(r, 6, v[2], v[ 7], v[ 8], v[13]); \
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G(r, 7, v[3], v[ 4], v[ 9], v[14]); \
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} while (0)
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ROUND(0);
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ROUND(1);
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ROUND(2);
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ROUND(3);
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ROUND(4);
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ROUND(5);
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ROUND(6);
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ROUND(7);
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ROUND(8);
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ROUND(9);
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#undef G
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#undef ROUND
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for (i = 0; i < 8; ++i)
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state->h[i] ^= v[i] ^ v[i + 8];
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block += BLAKE2S_BLOCK_LEN;
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--nblocks;
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}
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}
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static void blake2s_update(struct blake2s_state *state, const void *inp, size_t inlen)
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{
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const size_t fill = BLAKE2S_BLOCK_LEN - state->buflen;
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const uint8_t *in = inp;
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if (!inlen)
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return;
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if (inlen > fill) {
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memcpy(state->buf + state->buflen, in, fill);
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blake2s_compress(state, state->buf, 1, BLAKE2S_BLOCK_LEN);
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state->buflen = 0;
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in += fill;
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inlen -= fill;
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}
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if (inlen > BLAKE2S_BLOCK_LEN) {
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const size_t nblocks = DIV_ROUND_UP(inlen, BLAKE2S_BLOCK_LEN);
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blake2s_compress(state, in, nblocks - 1, BLAKE2S_BLOCK_LEN);
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in += BLAKE2S_BLOCK_LEN * (nblocks - 1);
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inlen -= BLAKE2S_BLOCK_LEN * (nblocks - 1);
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}
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memcpy(state->buf + state->buflen, in, inlen);
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state->buflen += inlen;
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}
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static void blake2s_final(struct blake2s_state *state, uint8_t *out)
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{
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blake2s_set_lastblock(state);
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memset(state->buf + state->buflen, 0, BLAKE2S_BLOCK_LEN - state->buflen);
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blake2s_compress(state, state->buf, 1, state->buflen);
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cpu_to_le32_array(state->h, ARRAY_SIZE(state->h));
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memcpy(out, state->h, state->outlen);
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}
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static ssize_t getrandom_full(void *buf, size_t count, unsigned int flags)
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{
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ssize_t ret, total = 0;
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uint8_t *p = buf;
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do {
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ret = getrandom(p, count, flags);
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if (ret < 0 && errno == EINTR)
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continue;
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else if (ret < 0)
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return ret;
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total += ret;
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p += ret;
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count -= ret;
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} while (count);
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return total;
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}
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static ssize_t read_full(int fd, void *buf, size_t count)
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{
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ssize_t ret, total = 0;
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uint8_t *p = buf;
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do {
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ret = read(fd, p, count);
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if (ret < 0 && errno == EINTR)
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continue;
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else if (ret < 0)
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return ret;
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else if (ret == 0)
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break;
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total += ret;
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p += ret;
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count -= ret;
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} while (count);
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return total;
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}
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static ssize_t write_full(int fd, const void *buf, size_t count)
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{
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ssize_t ret, total = 0;
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const uint8_t *p = buf;
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do {
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ret = write(fd, p, count);
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if (ret < 0 && errno == EINTR)
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continue;
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else if (ret < 0)
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return ret;
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total += ret;
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p += ret;
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count -= ret;
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} while (count);
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return total;
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}
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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_full(fd, poolsize_str, sizeof(poolsize_str) - 1) < 0) {
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ewarn("%s: Unable to determine pool size, falling back to %u bits: %s",
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applet, 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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}
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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_full(seed, len, GRND_NONBLOCK);
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if (ret == (ssize_t)len) {
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*is_creditable = true;
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return 0;
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} else if (ret < 0 && errno == ENOSYS) {
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struct pollfd random_fd = {
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.fd = open("/dev/random", O_RDONLY),
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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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close(random_fd.fd);
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} else if (getrandom_full(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 -1;
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ret = read_full(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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errno = -ret;
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return ret ? -1 : 0;
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}
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static int seed_rng(uint8_t *seed, size_t len, bool credit)
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{
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struct {
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int entropy_count;
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int buf_size;
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uint8_t buffer[MAX_SEED_LEN];
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} req = {
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.entropy_count = credit ? len * 8 : 0,
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.buf_size = len
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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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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/urandom", O_RDONLY);
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if (random_fd < 0)
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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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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, int dfd, bool credit, struct blake2s_state *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 = -1, ret = 0;
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fd = openat(dfd, 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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eerror("%s: Unable to open seed file: %s", applet, strerror(errno));
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goto out;
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}
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seed_len = read_full(fd, seed, sizeof(seed));
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if (seed_len < 0) {
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ret = -errno;
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eerror("%s: Unable to read seed file: %s", applet, strerror(errno));
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goto out;
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}
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if ((unlinkat(dfd, filename, 0) < 0 || fsync(dfd) < 0) && seed_len) {
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ret = -errno;
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eerror("%s: Unable to remove seed after reading, so not seeding: %s",
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applet, strerror(errno));
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goto out;
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}
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if (!seed_len)
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goto out;
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blake2s_update(hash, &seed_len, sizeof(seed_len));
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blake2s_update(hash, seed, seed_len);
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einfo("Seeding %zd bits %s crediting", seed_len * 8, credit ? "and" : "without");
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if (seed_rng(seed, seed_len, credit) < 0) {
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ret = -errno;
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eerror("%s: Unable to seed: %s", applet, strerror(errno));
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}
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out:
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if (fd >= 0)
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close(fd);
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errno = -ret;
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return ret ? -1 : 0;
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}
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int main(int argc, char **argv)
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{
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static const char seedrng_prefix[] = "SeedRNG v1 Old+New Prefix";
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static const char seedrng_failure[] = "SeedRNG v1 No New Seed Failure";
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int opt, fd, dfd, program_ret = 0;
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const char *seed_dir = NULL;
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uint8_t new_seed[MAX_SEED_LEN];
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size_t new_seed_len;
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bool new_seed_creditable;
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struct timespec realtime = { 0 }, boottime = { 0 };
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struct blake2s_state hash;
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bool skip_credit = false;
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applet = basename_c(argv[0]);
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while ((opt = getopt_long(argc, argv, getoptstring, longopts, (int *) 0)) != -1)
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|
{
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switch (opt) {
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case LONGOPT_SEED_DIR:
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if (!seed_dir)
|
|
seed_dir = optarg;
|
|
break;
|
|
case LONGOPT_SKIP_CREDIT:
|
|
skip_credit = true;
|
|
break;
|
|
case_RC_COMMON_GETOPT
|
|
}
|
|
}
|
|
if (!seed_dir)
|
|
seed_dir = DEFAULT_SEED_DIR;
|
|
if (getuid())
|
|
eerrorx("%s: superuser access is required", applet);
|
|
umask(0077);
|
|
|
|
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 seed directory: %s", applet, strerror(errno));
|
|
|
|
dfd = open(seed_dir, O_DIRECTORY | O_RDONLY);
|
|
if (dfd < 0 || flock(dfd, LOCK_EX) < 0)
|
|
eerrorx("%s: Unable to lock seed directory: %s", applet, strerror(errno));
|
|
|
|
if (seed_from_file_if_exists(NON_CREDITABLE_SEED, dfd, false, &hash) < 0)
|
|
program_ret |= 1 << 1;
|
|
if (seed_from_file_if_exists(CREDITABLE_SEED, dfd, !skip_credit, &hash) < 0)
|
|
program_ret |= 1 << 2;
|
|
|
|
new_seed_len = determine_optimal_seed_len();
|
|
if (read_new_seed(new_seed, new_seed_len, &new_seed_creditable) < 0) {
|
|
eerror("%s: Unable to read new seed: %s", applet, strerror(errno));
|
|
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 = openat(dfd, 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));
|
|
return program_ret | (1 << 4);
|
|
}
|
|
if (write_full(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));
|
|
return program_ret | (1 << 5);
|
|
}
|
|
if (new_seed_creditable && renameat(dfd, NON_CREDITABLE_SEED, dfd, CREDITABLE_SEED) < 0) {
|
|
ewarn("%s: Unable to make new seed creditable: %s", applet, strerror(errno));
|
|
return program_ret | (1 << 6);
|
|
}
|
|
return program_ret;
|
|
}
|