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Use NSS in crypto_rand.c
This is comparatively straightforward too, except for a couple of twists: * For as long as we're building with two crypto libraries, we want to seed _both_ their RNGs, and use _both_ their RNGs to improve the output of crypto_strongest_rand() * The NSS prng will sometimes refuse to generate huge outputs. When it does, we stretch the output with SHAKE. We only need this for the tests.
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@ -35,9 +35,22 @@
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#include "lib/testsupport/testsupport.h"
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#include "lib/fs/files.h"
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#ifdef ENABLE_NSS
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#include "lib/crypt_ops/crypto_nss_mgt.h"
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#include "lib/crypt_ops/crypto_digest.h"
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#endif
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#ifdef ENABLE_OPENSSL
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DISABLE_GCC_WARNING(redundant-decls)
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#include <openssl/rand.h>
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ENABLE_GCC_WARNING(redundant-decls)
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#endif
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#ifdef ENABLE_NSS
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#include <pk11pub.h>
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#include <secerr.h>
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#include <prerror.h>
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#endif
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#if __GNUC__ && GCC_VERSION >= 402
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#if GCC_VERSION >= 406
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@ -324,14 +337,21 @@ crypto_strongest_rand(uint8_t *out, size_t out_len)
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{
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#define DLEN SHA512_DIGEST_LENGTH
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/* We're going to hash DLEN bytes from the system RNG together with some
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* bytes from the openssl PRNG, in order to yield DLEN bytes.
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* bytes from the PRNGs from our crypto librar(y/ies), in order to yield
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* DLEN bytes.
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*/
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uint8_t inp[DLEN*2];
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uint8_t inp[DLEN*3];
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uint8_t tmp[DLEN];
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tor_assert(out);
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while (out_len) {
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crypto_rand((char*) inp, DLEN);
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if (crypto_strongest_rand_raw(inp+DLEN, DLEN) < 0) {
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memset(inp, 0, sizeof(inp));
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#ifdef ENABLE_OPENSSL
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RAND_bytes(inp, DLEN);
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#endif
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#ifdef ENABLE_NSS
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PK11_GenerateRandom(inp+DLEN, DLEN);
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#endif
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if (crypto_strongest_rand_raw(inp+DLEN*2, DLEN) < 0) {
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// LCOV_EXCL_START
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log_err(LD_CRYPTO, "Failed to load strong entropy when generating an "
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"important key. Exiting.");
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@ -354,12 +374,13 @@ crypto_strongest_rand(uint8_t *out, size_t out_len)
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#undef DLEN
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}
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#ifdef ENABLE_OPENSSL
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/**
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* Seed OpenSSL's random number generator with bytes from the operating
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* system. Return 0 on success, -1 on failure.
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**/
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int
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crypto_seed_rng(void)
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static int
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crypto_seed_openssl_rng(void)
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{
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int rand_poll_ok = 0, load_entropy_ok = 0;
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uint8_t buf[ADD_ENTROPY];
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@ -383,6 +404,52 @@ crypto_seed_rng(void)
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else
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return -1;
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}
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#endif
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#ifdef ENABLE_NSS
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/**
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* Seed OpenSSL's random number generator with bytes from the operating
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* system. Return 0 on success, -1 on failure.
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**/
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static int
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crypto_seed_nss_rng(void)
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{
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uint8_t buf[ADD_ENTROPY];
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int load_entropy_ok = !crypto_strongest_rand_raw(buf, sizeof(buf));
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if (load_entropy_ok) {
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if (PK11_RandomUpdate(buf, sizeof(buf)) != SECSuccess) {
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load_entropy_ok = 0;
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}
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}
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memwipe(buf, 0, sizeof(buf));
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return load_entropy_ok ? 0 : -1;
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}
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#endif
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/**
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* Seed the RNG for any and all crypto libraries that we're using with bytes
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* from the operating system. Return 0 on success, -1 on failure.
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*/
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int
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crypto_seed_rng(void)
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{
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int seeded = 0;
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#ifdef ENABLE_NSS
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if (crypto_seed_nss_rng() < 0)
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return -1;
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++seeded;
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#endif
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#ifdef ENABLE_OPENSSL
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if (crypto_seed_openssl_rng() < 0)
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return -1;
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++seeded;
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#endif
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tor_assert(seeded);
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return 0;
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}
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/**
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* Write <b>n</b> bytes of strong random data to <b>to</b>. Supports mocking
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@ -407,17 +474,44 @@ crypto_rand, (char *to, size_t n))
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void
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crypto_rand_unmocked(char *to, size_t n)
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{
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int r;
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if (n == 0)
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return;
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tor_assert(n < INT_MAX);
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tor_assert(to);
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r = RAND_bytes((unsigned char*)to, (int)n);
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#ifdef ENABLE_NSS
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SECStatus s = PK11_GenerateRandom((unsigned char*)to, (int)n);
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if (s != SECSuccess) {
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/* NSS rather sensibly might refuse to generate huge amounts of random
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* data at once. Unfortunately, our unit test do this in a couple of
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* places. To solve this issue, we use our XOF to stretch a shorter
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* output when a longer one is needed.
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*
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* Yes, this is secure. */
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/* This is longer than it needs to be; 1600 bits == 200 bytes is the
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* state-size of SHA3. */
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#define BUFLEN 512
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tor_assert(PR_GetError() == SEC_ERROR_INVALID_ARGS && n > BUFLEN);
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unsigned char buf[BUFLEN];
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s = PK11_GenerateRandom(buf, BUFLEN);
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tor_assert(s == SECSuccess);
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crypto_xof_t *xof = crypto_xof_new();
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crypto_xof_add_bytes(xof, buf, BUFLEN);
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crypto_xof_squeeze_bytes(xof, (unsigned char *)to, n);
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crypto_xof_free(xof);
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memwipe(buf, 0, BUFLEN);
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#undef BUFLEN
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}
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#else
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int r = RAND_bytes((unsigned char*)to, (int)n);
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/* We consider a PRNG failure non-survivable. Let's assert so that we get a
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* stack trace about where it happened.
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*/
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tor_assert(r >= 0);
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#endif
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}
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/**
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@ -9,6 +9,7 @@
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#include "lib/evloop/compat_libevent.h"
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#include "lib/evloop/timers.h"
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#include "lib/crypt_ops/crypto_init.h"
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#include "lib/crypt_ops/crypto_rand.h"
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#include "lib/log/util_bug.h"
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#include "lib/time/compat_time.h"
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@ -62,6 +63,10 @@ main(int argc, char **argv)
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memset(&cfg, 0, sizeof(cfg));
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tor_libevent_initialize(&cfg);
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timers_initialize();
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init_logging(1);
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if (crypto_global_init(0, NULL, NULL) < 0)
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return 1;
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int i;
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int ret;
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