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tor/src/common/crypto.c
Nick Mathewson e6d6347690 Merge remote-tracking branch 'public/bug26005_034'
2018-05-09 08:23:27 -04:00

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/* Copyright (c) 2001, Matej Pfajfar.
* Copyright (c) 2001-2004, Roger Dingledine.
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2017, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file crypto.c
* \brief Wrapper functions to present a consistent interface to
* public-key and symmetric cryptography operations from OpenSSL and
* other places.
**/
#include "orconfig.h"
#ifdef _WIN32
#include <winsock2.h>
#include <windows.h>
#include <wincrypt.h>
/* Windows defines this; so does OpenSSL 0.9.8h and later. We don't actually
* use either definition. */
#undef OCSP_RESPONSE
#endif /* defined(_WIN32) */
#define CRYPTO_PRIVATE
#include "compat_openssl.h"
#include "crypto.h"
#include "crypto_curve25519.h"
#include "crypto_digest.h"
#include "crypto_ed25519.h"
#include "crypto_format.h"
#include "crypto_rand.h"
#include "crypto_rsa.h"
#include "crypto_util.h"
DISABLE_GCC_WARNING(redundant-decls)
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/engine.h>
#include <openssl/bn.h>
#include <openssl/dh.h>
#include <openssl/conf.h>
#include <openssl/hmac.h>
#include <openssl/ssl.h>
ENABLE_GCC_WARNING(redundant-decls)
#if __GNUC__ && GCC_VERSION >= 402
#if GCC_VERSION >= 406
#pragma GCC diagnostic pop
#else
#pragma GCC diagnostic warning "-Wredundant-decls"
#endif
#endif /* __GNUC__ && GCC_VERSION >= 402 */
#ifdef HAVE_CTYPE_H
#include <ctype.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include "torlog.h"
#include "torint.h"
#include "aes.h"
#include "util.h"
#include "container.h"
#include "compat.h"
#include "sandbox.h"
#include "util_format.h"
#include "keccak-tiny/keccak-tiny.h"
/** A structure to hold the first half (x, g^x) of a Diffie-Hellman handshake
* while we're waiting for the second.*/
struct crypto_dh_t {
DH *dh; /**< The openssl DH object */
};
static int tor_check_dh_key(int severity, const BIGNUM *bn);
/** Boolean: has OpenSSL's crypto been initialized? */
static int crypto_early_initialized_ = 0;
/** Boolean: has OpenSSL's crypto been initialized? */
static int crypto_global_initialized_ = 0;
/** Log all pending crypto errors at level <b>severity</b>. Use
* <b>doing</b> to describe our current activities.
*/
static void
crypto_log_errors(int severity, const char *doing)
{
unsigned long err;
const char *msg, *lib, *func;
while ((err = ERR_get_error()) != 0) {
msg = (const char*)ERR_reason_error_string(err);
lib = (const char*)ERR_lib_error_string(err);
func = (const char*)ERR_func_error_string(err);
if (!msg) msg = "(null)";
if (!lib) lib = "(null)";
if (!func) func = "(null)";
if (BUG(!doing)) doing = "(null)";
tor_log(severity, LD_CRYPTO, "crypto error while %s: %s (in %s:%s)",
doing, msg, lib, func);
}
}
#ifndef DISABLE_ENGINES
/** Log any OpenSSL engines we're using at NOTICE. */
static void
log_engine(const char *fn, ENGINE *e)
{
if (e) {
const char *name, *id;
name = ENGINE_get_name(e);
id = ENGINE_get_id(e);
log_notice(LD_CRYPTO, "Default OpenSSL engine for %s is %s [%s]",
fn, name?name:"?", id?id:"?");
} else {
log_info(LD_CRYPTO, "Using default implementation for %s", fn);
}
}
#endif /* !defined(DISABLE_ENGINES) */
#ifndef DISABLE_ENGINES
/** Try to load an engine in a shared library via fully qualified path.
*/
static ENGINE *
try_load_engine(const char *path, const char *engine)
{
ENGINE *e = ENGINE_by_id("dynamic");
if (e) {
if (!ENGINE_ctrl_cmd_string(e, "ID", engine, 0) ||
!ENGINE_ctrl_cmd_string(e, "DIR_LOAD", "2", 0) ||
!ENGINE_ctrl_cmd_string(e, "DIR_ADD", path, 0) ||
!ENGINE_ctrl_cmd_string(e, "LOAD", NULL, 0)) {
ENGINE_free(e);
e = NULL;
}
}
return e;
}
#endif /* !defined(DISABLE_ENGINES) */
static int have_seeded_siphash = 0;
/** Set up the siphash key if we haven't already done so. */
int
crypto_init_siphash_key(void)
{
struct sipkey key;
if (have_seeded_siphash)
return 0;
crypto_rand((char*) &key, sizeof(key));
siphash_set_global_key(&key);
have_seeded_siphash = 1;
return 0;
}
/** Initialize the crypto library. Return 0 on success, -1 on failure.
*/
int
crypto_early_init(void)
{
if (!crypto_early_initialized_) {
crypto_early_initialized_ = 1;
#ifdef OPENSSL_1_1_API
OPENSSL_init_ssl(OPENSSL_INIT_LOAD_SSL_STRINGS |
OPENSSL_INIT_LOAD_CRYPTO_STRINGS |
OPENSSL_INIT_ADD_ALL_CIPHERS |
OPENSSL_INIT_ADD_ALL_DIGESTS, NULL);
#else
ERR_load_crypto_strings();
OpenSSL_add_all_algorithms();
#endif
setup_openssl_threading();
unsigned long version_num = OpenSSL_version_num();
const char *version_str = OpenSSL_version(OPENSSL_VERSION);
if (version_num == OPENSSL_VERSION_NUMBER &&
!strcmp(version_str, OPENSSL_VERSION_TEXT)) {
log_info(LD_CRYPTO, "OpenSSL version matches version from headers "
"(%lx: %s).", version_num, version_str);
} else {
log_warn(LD_CRYPTO, "OpenSSL version from headers does not match the "
"version we're running with. If you get weird crashes, that "
"might be why. (Compiled with %lx: %s; running with %lx: %s).",
(unsigned long)OPENSSL_VERSION_NUMBER, OPENSSL_VERSION_TEXT,
version_num, version_str);
}
crypto_force_rand_ssleay();
if (crypto_seed_rng() < 0)
return -1;
if (crypto_init_siphash_key() < 0)
return -1;
curve25519_init();
ed25519_init();
}
return 0;
}
/** Initialize the crypto library. Return 0 on success, -1 on failure.
*/
int
crypto_global_init(int useAccel, const char *accelName, const char *accelDir)
{
if (!crypto_global_initialized_) {
if (crypto_early_init() < 0)
return -1;
crypto_global_initialized_ = 1;
if (useAccel > 0) {
#ifdef DISABLE_ENGINES
(void)accelName;
(void)accelDir;
log_warn(LD_CRYPTO, "No OpenSSL hardware acceleration support enabled.");
#else
ENGINE *e = NULL;
log_info(LD_CRYPTO, "Initializing OpenSSL engine support.");
ENGINE_load_builtin_engines();
ENGINE_register_all_complete();
if (accelName) {
if (accelDir) {
log_info(LD_CRYPTO, "Trying to load dynamic OpenSSL engine \"%s\""
" via path \"%s\".", accelName, accelDir);
e = try_load_engine(accelName, accelDir);
} else {
log_info(LD_CRYPTO, "Initializing dynamic OpenSSL engine \"%s\""
" acceleration support.", accelName);
e = ENGINE_by_id(accelName);
}
if (!e) {
log_warn(LD_CRYPTO, "Unable to load dynamic OpenSSL engine \"%s\".",
accelName);
} else {
log_info(LD_CRYPTO, "Loaded dynamic OpenSSL engine \"%s\".",
accelName);
}
}
if (e) {
log_info(LD_CRYPTO, "Loaded OpenSSL hardware acceleration engine,"
" setting default ciphers.");
ENGINE_set_default(e, ENGINE_METHOD_ALL);
}
/* Log, if available, the intersection of the set of algorithms
used by Tor and the set of algorithms available in the engine */
log_engine("RSA", ENGINE_get_default_RSA());
log_engine("DH", ENGINE_get_default_DH());
#ifdef OPENSSL_1_1_API
log_engine("EC", ENGINE_get_default_EC());
#else
log_engine("ECDH", ENGINE_get_default_ECDH());
log_engine("ECDSA", ENGINE_get_default_ECDSA());
#endif /* defined(OPENSSL_1_1_API) */
log_engine("RAND", ENGINE_get_default_RAND());
log_engine("RAND (which we will not use)", ENGINE_get_default_RAND());
log_engine("SHA1", ENGINE_get_digest_engine(NID_sha1));
log_engine("3DES-CBC", ENGINE_get_cipher_engine(NID_des_ede3_cbc));
log_engine("AES-128-ECB", ENGINE_get_cipher_engine(NID_aes_128_ecb));
log_engine("AES-128-CBC", ENGINE_get_cipher_engine(NID_aes_128_cbc));
#ifdef NID_aes_128_ctr
log_engine("AES-128-CTR", ENGINE_get_cipher_engine(NID_aes_128_ctr));
#endif
#ifdef NID_aes_128_gcm
log_engine("AES-128-GCM", ENGINE_get_cipher_engine(NID_aes_128_gcm));
#endif
log_engine("AES-256-CBC", ENGINE_get_cipher_engine(NID_aes_256_cbc));
#ifdef NID_aes_256_gcm
log_engine("AES-256-GCM", ENGINE_get_cipher_engine(NID_aes_256_gcm));
#endif
#endif /* defined(DISABLE_ENGINES) */
} else {
log_info(LD_CRYPTO, "NOT using OpenSSL engine support.");
}
if (crypto_force_rand_ssleay()) {
if (crypto_seed_rng() < 0)
return -1;
}
evaluate_evp_for_aes(-1);
evaluate_ctr_for_aes();
}
return 0;
}
/** Free crypto resources held by this thread. */
void
crypto_thread_cleanup(void)
{
#ifndef NEW_THREAD_API
ERR_remove_thread_state(NULL);
#endif
}
/** Used by tortls.c: Get the DH* from a crypto_dh_t.
*/
DH *
crypto_dh_get_dh_(crypto_dh_t *dh)
{
return dh->dh;
}
/** Allocate and return a new symmetric cipher using the provided key and iv.
* The key is <b>bits</b> bits long; the IV is CIPHER_IV_LEN bytes. Both
* must be provided. Key length must be 128, 192, or 256 */
crypto_cipher_t *
crypto_cipher_new_with_iv_and_bits(const uint8_t *key,
const uint8_t *iv,
int bits)
{
tor_assert(key);
tor_assert(iv);
return aes_new_cipher((const uint8_t*)key, (const uint8_t*)iv, bits);
}
/** Allocate and return a new symmetric cipher using the provided key and iv.
* The key is CIPHER_KEY_LEN bytes; the IV is CIPHER_IV_LEN bytes. Both
* must be provided.
*/
crypto_cipher_t *
crypto_cipher_new_with_iv(const char *key, const char *iv)
{
return crypto_cipher_new_with_iv_and_bits((uint8_t*)key, (uint8_t*)iv,
128);
}
/** Return a new crypto_cipher_t with the provided <b>key</b> and an IV of all
* zero bytes and key length <b>bits</b>. Key length must be 128, 192, or
* 256. */
crypto_cipher_t *
crypto_cipher_new_with_bits(const char *key, int bits)
{
char zeroiv[CIPHER_IV_LEN];
memset(zeroiv, 0, sizeof(zeroiv));
return crypto_cipher_new_with_iv_and_bits((uint8_t*)key, (uint8_t*)zeroiv,
bits);
}
/** Return a new crypto_cipher_t with the provided <b>key</b> (of
* CIPHER_KEY_LEN bytes) and an IV of all zero bytes. */
crypto_cipher_t *
crypto_cipher_new(const char *key)
{
return crypto_cipher_new_with_bits(key, 128);
}
/** Free a symmetric cipher.
*/
void
crypto_cipher_free_(crypto_cipher_t *env)
{
if (!env)
return;
aes_cipher_free(env);
}
/** Copy <b>in</b> to the <b>outlen</b>-byte buffer <b>out</b>, adding spaces
* every four characters. */
void
crypto_add_spaces_to_fp(char *out, size_t outlen, const char *in)
{
int n = 0;
char *end = out+outlen;
tor_assert(outlen < SIZE_T_CEILING);
while (*in && out<end) {
*out++ = *in++;
if (++n == 4 && *in && out<end) {
n = 0;
*out++ = ' ';
}
}
tor_assert(out<end);
*out = '\0';
}
/* symmetric crypto */
/** Encrypt <b>fromlen</b> bytes from <b>from</b> using the cipher
* <b>env</b>; on success, store the result to <b>to</b> and return 0.
* Does not check for failure.
*/
int
crypto_cipher_encrypt(crypto_cipher_t *env, char *to,
const char *from, size_t fromlen)
{
tor_assert(env);
tor_assert(env);
tor_assert(from);
tor_assert(fromlen);
tor_assert(to);
tor_assert(fromlen < SIZE_T_CEILING);
memcpy(to, from, fromlen);
aes_crypt_inplace(env, to, fromlen);
return 0;
}
/** Decrypt <b>fromlen</b> bytes from <b>from</b> using the cipher
* <b>env</b>; on success, store the result to <b>to</b> and return 0.
* Does not check for failure.
*/
int
crypto_cipher_decrypt(crypto_cipher_t *env, char *to,
const char *from, size_t fromlen)
{
tor_assert(env);
tor_assert(from);
tor_assert(to);
tor_assert(fromlen < SIZE_T_CEILING);
memcpy(to, from, fromlen);
aes_crypt_inplace(env, to, fromlen);
return 0;
}
/** Encrypt <b>len</b> bytes on <b>from</b> using the cipher in <b>env</b>;
* on success. Does not check for failure.
*/
void
crypto_cipher_crypt_inplace(crypto_cipher_t *env, char *buf, size_t len)
{
tor_assert(len < SIZE_T_CEILING);
aes_crypt_inplace(env, buf, len);
}
/** Encrypt <b>fromlen</b> bytes (at least 1) from <b>from</b> with the key in
* <b>key</b> to the buffer in <b>to</b> of length
* <b>tolen</b>. <b>tolen</b> must be at least <b>fromlen</b> plus
* CIPHER_IV_LEN bytes for the initialization vector. On success, return the
* number of bytes written, on failure, return -1.
*/
int
crypto_cipher_encrypt_with_iv(const char *key,
char *to, size_t tolen,
const char *from, size_t fromlen)
{
crypto_cipher_t *cipher;
tor_assert(from);
tor_assert(to);
tor_assert(fromlen < INT_MAX);
if (fromlen < 1)
return -1;
if (tolen < fromlen + CIPHER_IV_LEN)
return -1;
char iv[CIPHER_IV_LEN];
crypto_rand(iv, sizeof(iv));
cipher = crypto_cipher_new_with_iv(key, iv);
memcpy(to, iv, CIPHER_IV_LEN);
crypto_cipher_encrypt(cipher, to+CIPHER_IV_LEN, from, fromlen);
crypto_cipher_free(cipher);
memwipe(iv, 0, sizeof(iv));
return (int)(fromlen + CIPHER_IV_LEN);
}
/** Decrypt <b>fromlen</b> bytes (at least 1+CIPHER_IV_LEN) from <b>from</b>
* with the key in <b>key</b> to the buffer in <b>to</b> of length
* <b>tolen</b>. <b>tolen</b> must be at least <b>fromlen</b> minus
* CIPHER_IV_LEN bytes for the initialization vector. On success, return the
* number of bytes written, on failure, return -1.
*/
int
crypto_cipher_decrypt_with_iv(const char *key,
char *to, size_t tolen,
const char *from, size_t fromlen)
{
crypto_cipher_t *cipher;
tor_assert(key);
tor_assert(from);
tor_assert(to);
tor_assert(fromlen < INT_MAX);
if (fromlen <= CIPHER_IV_LEN)
return -1;
if (tolen < fromlen - CIPHER_IV_LEN)
return -1;
cipher = crypto_cipher_new_with_iv(key, from);
crypto_cipher_encrypt(cipher, to, from+CIPHER_IV_LEN, fromlen-CIPHER_IV_LEN);
crypto_cipher_free(cipher);
return (int)(fromlen - CIPHER_IV_LEN);
}
/* DH */
/** Our DH 'g' parameter */
#define DH_GENERATOR 2
/** Shared P parameter for our circuit-crypto DH key exchanges. */
static BIGNUM *dh_param_p = NULL;
/** Shared P parameter for our TLS DH key exchanges. */
static BIGNUM *dh_param_p_tls = NULL;
/** Shared G parameter for our DH key exchanges. */
static BIGNUM *dh_param_g = NULL;
/** Validate a given set of Diffie-Hellman parameters. This is moderately
* computationally expensive (milliseconds), so should only be called when
* the DH parameters change. Returns 0 on success, * -1 on failure.
*/
static int
crypto_validate_dh_params(const BIGNUM *p, const BIGNUM *g)
{
DH *dh = NULL;
int ret = -1;
/* Copy into a temporary DH object, just so that DH_check() can be called. */
if (!(dh = DH_new()))
goto out;
#ifdef OPENSSL_1_1_API
BIGNUM *dh_p, *dh_g;
if (!(dh_p = BN_dup(p)))
goto out;
if (!(dh_g = BN_dup(g)))
goto out;
if (!DH_set0_pqg(dh, dh_p, NULL, dh_g))
goto out;
#else /* !(defined(OPENSSL_1_1_API)) */
if (!(dh->p = BN_dup(p)))
goto out;
if (!(dh->g = BN_dup(g)))
goto out;
#endif /* defined(OPENSSL_1_1_API) */
/* Perform the validation. */
int codes = 0;
if (!DH_check(dh, &codes))
goto out;
if (BN_is_word(g, DH_GENERATOR_2)) {
/* Per https://wiki.openssl.org/index.php/Diffie-Hellman_parameters
*
* OpenSSL checks the prime is congruent to 11 when g = 2; while the
* IETF's primes are congruent to 23 when g = 2.
*/
BN_ULONG residue = BN_mod_word(p, 24);
if (residue == 11 || residue == 23)
codes &= ~DH_NOT_SUITABLE_GENERATOR;
}
if (codes != 0) /* Specifics on why the params suck is irrelevant. */
goto out;
/* Things are probably not evil. */
ret = 0;
out:
if (dh)
DH_free(dh);
return ret;
}
/** Set the global Diffie-Hellman generator, used for both TLS and internal
* DH stuff.
*/
static void
crypto_set_dh_generator(void)
{
BIGNUM *generator;
int r;
if (dh_param_g)
return;
generator = BN_new();
tor_assert(generator);
r = BN_set_word(generator, DH_GENERATOR);
tor_assert(r);
dh_param_g = generator;
}
/** Set the global TLS Diffie-Hellman modulus. Use the Apache mod_ssl DH
* modulus. */
void
crypto_set_tls_dh_prime(void)
{
BIGNUM *tls_prime = NULL;
int r;
/* If the space is occupied, free the previous TLS DH prime */
if (BUG(dh_param_p_tls)) {
/* LCOV_EXCL_START
*
* We shouldn't be calling this twice.
*/
BN_clear_free(dh_param_p_tls);
dh_param_p_tls = NULL;
/* LCOV_EXCL_STOP */
}
tls_prime = BN_new();
tor_assert(tls_prime);
/* This is the 1024-bit safe prime that Apache uses for its DH stuff; see
* modules/ssl/ssl_engine_dh.c; Apache also uses a generator of 2 with this
* prime.
*/
r = BN_hex2bn(&tls_prime,
"D67DE440CBBBDC1936D693D34AFD0AD50C84D239A45F520BB88174CB98"
"BCE951849F912E639C72FB13B4B4D7177E16D55AC179BA420B2A29FE324A"
"467A635E81FF5901377BEDDCFD33168A461AAD3B72DAE8860078045B07A7"
"DBCA7874087D1510EA9FCC9DDD330507DD62DB88AEAA747DE0F4D6E2BD68"
"B0E7393E0F24218EB3");
tor_assert(r);
tor_assert(tls_prime);
dh_param_p_tls = tls_prime;
crypto_set_dh_generator();
tor_assert(0 == crypto_validate_dh_params(dh_param_p_tls, dh_param_g));
}
/** Initialize dh_param_p and dh_param_g if they are not already
* set. */
static void
init_dh_param(void)
{
BIGNUM *circuit_dh_prime;
int r;
if (BUG(dh_param_p && dh_param_g))
return; // LCOV_EXCL_LINE This function isn't supposed to be called twice.
circuit_dh_prime = BN_new();
tor_assert(circuit_dh_prime);
/* This is from rfc2409, section 6.2. It's a safe prime, and
supposedly it equals:
2^1024 - 2^960 - 1 + 2^64 * { [2^894 pi] + 129093 }.
*/
r = BN_hex2bn(&circuit_dh_prime,
"FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E08"
"8A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B"
"302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9"
"A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE6"
"49286651ECE65381FFFFFFFFFFFFFFFF");
tor_assert(r);
/* Set the new values as the global DH parameters. */
dh_param_p = circuit_dh_prime;
crypto_set_dh_generator();
tor_assert(0 == crypto_validate_dh_params(dh_param_p, dh_param_g));
if (!dh_param_p_tls) {
crypto_set_tls_dh_prime();
}
}
/** Number of bits to use when choosing the x or y value in a Diffie-Hellman
* handshake. Since we exponentiate by this value, choosing a smaller one
* lets our handhake go faster.
*/
#define DH_PRIVATE_KEY_BITS 320
/** Allocate and return a new DH object for a key exchange. Returns NULL on
* failure.
*/
crypto_dh_t *
crypto_dh_new(int dh_type)
{
crypto_dh_t *res = tor_malloc_zero(sizeof(crypto_dh_t));
tor_assert(dh_type == DH_TYPE_CIRCUIT || dh_type == DH_TYPE_TLS ||
dh_type == DH_TYPE_REND);
if (!dh_param_p)
init_dh_param();
if (!(res->dh = DH_new()))
goto err;
#ifdef OPENSSL_1_1_API
BIGNUM *dh_p = NULL, *dh_g = NULL;
if (dh_type == DH_TYPE_TLS) {
dh_p = BN_dup(dh_param_p_tls);
} else {
dh_p = BN_dup(dh_param_p);
}
if (!dh_p)
goto err;
dh_g = BN_dup(dh_param_g);
if (!dh_g) {
BN_free(dh_p);
goto err;
}
if (!DH_set0_pqg(res->dh, dh_p, NULL, dh_g)) {
goto err;
}
if (!DH_set_length(res->dh, DH_PRIVATE_KEY_BITS))
goto err;
#else /* !(defined(OPENSSL_1_1_API)) */
if (dh_type == DH_TYPE_TLS) {
if (!(res->dh->p = BN_dup(dh_param_p_tls)))
goto err;
} else {
if (!(res->dh->p = BN_dup(dh_param_p)))
goto err;
}
if (!(res->dh->g = BN_dup(dh_param_g)))
goto err;
res->dh->length = DH_PRIVATE_KEY_BITS;
#endif /* defined(OPENSSL_1_1_API) */
return res;
/* LCOV_EXCL_START
* This error condition is only reached when an allocation fails */
err:
crypto_log_errors(LOG_WARN, "creating DH object");
if (res->dh) DH_free(res->dh); /* frees p and g too */
tor_free(res);
return NULL;
/* LCOV_EXCL_STOP */
}
/** Return a copy of <b>dh</b>, sharing its internal state. */
crypto_dh_t *
crypto_dh_dup(const crypto_dh_t *dh)
{
crypto_dh_t *dh_new = tor_malloc_zero(sizeof(crypto_dh_t));
tor_assert(dh);
tor_assert(dh->dh);
dh_new->dh = dh->dh;
DH_up_ref(dh->dh);
return dh_new;
}
/** Return the length of the DH key in <b>dh</b>, in bytes.
*/
int
crypto_dh_get_bytes(crypto_dh_t *dh)
{
tor_assert(dh);
return DH_size(dh->dh);
}
/** Generate \<x,g^x\> for our part of the key exchange. Return 0 on
* success, -1 on failure.
*/
int
crypto_dh_generate_public(crypto_dh_t *dh)
{
#ifndef OPENSSL_1_1_API
again:
#endif
if (!DH_generate_key(dh->dh)) {
/* LCOV_EXCL_START
* To test this we would need some way to tell openssl to break DH. */
crypto_log_errors(LOG_WARN, "generating DH key");
return -1;
/* LCOV_EXCL_STOP */
}
#ifdef OPENSSL_1_1_API
/* OpenSSL 1.1.x doesn't appear to let you regenerate a DH key, without
* recreating the DH object. I have no idea what sort of aliasing madness
* can occur here, so do the check, and just bail on failure.
*/
const BIGNUM *pub_key, *priv_key;
DH_get0_key(dh->dh, &pub_key, &priv_key);
if (tor_check_dh_key(LOG_WARN, pub_key)<0) {
log_warn(LD_CRYPTO, "Weird! Our own DH key was invalid. I guess once-in-"
"the-universe chances really do happen. Treating as a failure.");
return -1;
}
#else /* !(defined(OPENSSL_1_1_API)) */
if (tor_check_dh_key(LOG_WARN, dh->dh->pub_key)<0) {
/* LCOV_EXCL_START
* If this happens, then openssl's DH implementation is busted. */
log_warn(LD_CRYPTO, "Weird! Our own DH key was invalid. I guess once-in-"
"the-universe chances really do happen. Trying again.");
/* Free and clear the keys, so OpenSSL will actually try again. */
BN_clear_free(dh->dh->pub_key);
BN_clear_free(dh->dh->priv_key);
dh->dh->pub_key = dh->dh->priv_key = NULL;
goto again;
/* LCOV_EXCL_STOP */
}
#endif /* defined(OPENSSL_1_1_API) */
return 0;
}
/** Generate g^x as necessary, and write the g^x for the key exchange
* as a <b>pubkey_len</b>-byte value into <b>pubkey</b>. Return 0 on
* success, -1 on failure. <b>pubkey_len</b> must be \>= DH_BYTES.
*/
int
crypto_dh_get_public(crypto_dh_t *dh, char *pubkey, size_t pubkey_len)
{
int bytes;
tor_assert(dh);
const BIGNUM *dh_pub;
#ifdef OPENSSL_1_1_API
const BIGNUM *dh_priv;
DH_get0_key(dh->dh, &dh_pub, &dh_priv);
#else
dh_pub = dh->dh->pub_key;
#endif /* defined(OPENSSL_1_1_API) */
if (!dh_pub) {
if (crypto_dh_generate_public(dh)<0)
return -1;
else {
#ifdef OPENSSL_1_1_API
DH_get0_key(dh->dh, &dh_pub, &dh_priv);
#else
dh_pub = dh->dh->pub_key;
#endif
}
}
tor_assert(dh_pub);
bytes = BN_num_bytes(dh_pub);
tor_assert(bytes >= 0);
if (pubkey_len < (size_t)bytes) {
log_warn(LD_CRYPTO,
"Weird! pubkey_len (%d) was smaller than DH_BYTES (%d)",
(int) pubkey_len, bytes);
return -1;
}
memset(pubkey, 0, pubkey_len);
BN_bn2bin(dh_pub, (unsigned char*)(pubkey+(pubkey_len-bytes)));
return 0;
}
/** Check for bad Diffie-Hellman public keys (g^x). Return 0 if the key is
* okay (in the subgroup [2,p-2]), or -1 if it's bad.
* See http://www.cl.cam.ac.uk/ftp/users/rja14/psandqs.ps.gz for some tips.
*/
static int
tor_check_dh_key(int severity, const BIGNUM *bn)
{
BIGNUM *x;
char *s;
tor_assert(bn);
x = BN_new();
tor_assert(x);
if (BUG(!dh_param_p))
init_dh_param(); //LCOV_EXCL_LINE we already checked whether we did this.
BN_set_word(x, 1);
if (BN_cmp(bn,x)<=0) {
log_fn(severity, LD_CRYPTO, "DH key must be at least 2.");
goto err;
}
BN_copy(x,dh_param_p);
BN_sub_word(x, 1);
if (BN_cmp(bn,x)>=0) {
log_fn(severity, LD_CRYPTO, "DH key must be at most p-2.");
goto err;
}
BN_clear_free(x);
return 0;
err:
BN_clear_free(x);
s = BN_bn2hex(bn);
log_fn(severity, LD_CRYPTO, "Rejecting insecure DH key [%s]", s);
OPENSSL_free(s);
return -1;
}
/** Given a DH key exchange object, and our peer's value of g^y (as a
* <b>pubkey_len</b>-byte value in <b>pubkey</b>) generate
* <b>secret_bytes_out</b> bytes of shared key material and write them
* to <b>secret_out</b>. Return the number of bytes generated on success,
* or -1 on failure.
*
* (We generate key material by computing
* SHA1( g^xy || "\x00" ) || SHA1( g^xy || "\x01" ) || ...
* where || is concatenation.)
*/
ssize_t
crypto_dh_compute_secret(int severity, crypto_dh_t *dh,
const char *pubkey, size_t pubkey_len,
char *secret_out, size_t secret_bytes_out)
{
char *secret_tmp = NULL;
BIGNUM *pubkey_bn = NULL;
size_t secret_len=0, secret_tmp_len=0;
int result=0;
tor_assert(dh);
tor_assert(secret_bytes_out/DIGEST_LEN <= 255);
tor_assert(pubkey_len < INT_MAX);
if (!(pubkey_bn = BN_bin2bn((const unsigned char*)pubkey,
(int)pubkey_len, NULL)))
goto error;
if (tor_check_dh_key(severity, pubkey_bn)<0) {
/* Check for invalid public keys. */
log_fn(severity, LD_CRYPTO,"Rejected invalid g^x");
goto error;
}
secret_tmp_len = crypto_dh_get_bytes(dh);
secret_tmp = tor_malloc(secret_tmp_len);
result = DH_compute_key((unsigned char*)secret_tmp, pubkey_bn, dh->dh);
if (result < 0) {
log_warn(LD_CRYPTO,"DH_compute_key() failed.");
goto error;
}
secret_len = result;
if (crypto_expand_key_material_TAP((uint8_t*)secret_tmp, secret_len,
(uint8_t*)secret_out, secret_bytes_out)<0)
goto error;
secret_len = secret_bytes_out;
goto done;
error:
result = -1;
done:
crypto_log_errors(LOG_WARN, "completing DH handshake");
if (pubkey_bn)
BN_clear_free(pubkey_bn);
if (secret_tmp) {
memwipe(secret_tmp, 0, secret_tmp_len);
tor_free(secret_tmp);
}
if (result < 0)
return result;
else
return secret_len;
}
/** Given <b>key_in_len</b> bytes of negotiated randomness in <b>key_in</b>
* ("K"), expand it into <b>key_out_len</b> bytes of negotiated key material in
* <b>key_out</b> by taking the first <b>key_out_len</b> bytes of
* H(K | [00]) | H(K | [01]) | ....
*
* This is the key expansion algorithm used in the "TAP" circuit extension
* mechanism; it shouldn't be used for new protocols.
*
* Return 0 on success, -1 on failure.
*/
int
crypto_expand_key_material_TAP(const uint8_t *key_in, size_t key_in_len,
uint8_t *key_out, size_t key_out_len)
{
int i, r = -1;
uint8_t *cp, *tmp = tor_malloc(key_in_len+1);
uint8_t digest[DIGEST_LEN];
/* If we try to get more than this amount of key data, we'll repeat blocks.*/
tor_assert(key_out_len <= DIGEST_LEN*256);
memcpy(tmp, key_in, key_in_len);
for (cp = key_out, i=0; cp < key_out+key_out_len;
++i, cp += DIGEST_LEN) {
tmp[key_in_len] = i;
if (crypto_digest((char*)digest, (const char *)tmp, key_in_len+1) < 0)
goto exit;
memcpy(cp, digest, MIN(DIGEST_LEN, key_out_len-(cp-key_out)));
}
r = 0;
exit:
memwipe(tmp, 0, key_in_len+1);
tor_free(tmp);
memwipe(digest, 0, sizeof(digest));
return r;
}
/** Expand some secret key material according to RFC5869, using SHA256 as the
* underlying hash. The <b>key_in_len</b> bytes at <b>key_in</b> are the
* secret key material; the <b>salt_in_len</b> bytes at <b>salt_in</b> and the
* <b>info_in_len</b> bytes in <b>info_in_len</b> are the algorithm's "salt"
* and "info" parameters respectively. On success, write <b>key_out_len</b>
* bytes to <b>key_out</b> and return 0. Assert on failure.
*/
int
crypto_expand_key_material_rfc5869_sha256(
const uint8_t *key_in, size_t key_in_len,
const uint8_t *salt_in, size_t salt_in_len,
const uint8_t *info_in, size_t info_in_len,
uint8_t *key_out, size_t key_out_len)
{
uint8_t prk[DIGEST256_LEN];
uint8_t tmp[DIGEST256_LEN + 128 + 1];
uint8_t mac[DIGEST256_LEN];
int i;
uint8_t *outp;
size_t tmp_len;
crypto_hmac_sha256((char*)prk,
(const char*)salt_in, salt_in_len,
(const char*)key_in, key_in_len);
/* If we try to get more than this amount of key data, we'll repeat blocks.*/
tor_assert(key_out_len <= DIGEST256_LEN * 256);
tor_assert(info_in_len <= 128);
memset(tmp, 0, sizeof(tmp));
outp = key_out;
i = 1;
while (key_out_len) {
size_t n;
if (i > 1) {
memcpy(tmp, mac, DIGEST256_LEN);
memcpy(tmp+DIGEST256_LEN, info_in, info_in_len);
tmp[DIGEST256_LEN+info_in_len] = i;
tmp_len = DIGEST256_LEN + info_in_len + 1;
} else {
memcpy(tmp, info_in, info_in_len);
tmp[info_in_len] = i;
tmp_len = info_in_len + 1;
}
crypto_hmac_sha256((char*)mac,
(const char*)prk, DIGEST256_LEN,
(const char*)tmp, tmp_len);
n = key_out_len < DIGEST256_LEN ? key_out_len : DIGEST256_LEN;
memcpy(outp, mac, n);
key_out_len -= n;
outp += n;
++i;
}
memwipe(tmp, 0, sizeof(tmp));
memwipe(mac, 0, sizeof(mac));
return 0;
}
/** Free a DH key exchange object.
*/
void
crypto_dh_free_(crypto_dh_t *dh)
{
if (!dh)
return;
tor_assert(dh->dh);
DH_free(dh->dh);
tor_free(dh);
}
/** @{ */
/** Uninitialize the crypto library. Return 0 on success. Does not detect
* failure.
*/
int
crypto_global_cleanup(void)
{
#ifndef OPENSSL_1_1_API
EVP_cleanup();
#endif
#ifndef NEW_THREAD_API
ERR_remove_thread_state(NULL);
#endif
#ifndef OPENSSL_1_1_API
ERR_free_strings();
#endif
if (dh_param_p)
BN_clear_free(dh_param_p);
if (dh_param_p_tls)
BN_clear_free(dh_param_p_tls);
if (dh_param_g)
BN_clear_free(dh_param_g);
dh_param_p = dh_param_p_tls = dh_param_g = NULL;
#ifndef DISABLE_ENGINES
#ifndef OPENSSL_1_1_API
ENGINE_cleanup();
#endif
#endif
CONF_modules_unload(1);
#ifndef OPENSSL_1_1_API
CRYPTO_cleanup_all_ex_data();
#endif
crypto_openssl_free_all();
crypto_early_initialized_ = 0;
crypto_global_initialized_ = 0;
have_seeded_siphash = 0;
siphash_unset_global_key();
return 0;
}
/** @} */
#ifdef USE_DMALLOC
/** Tell the crypto library to use Tor's allocation functions rather than
* calling libc's allocation functions directly. Return 0 on success, -1
* on failure. */
int
crypto_use_tor_alloc_functions(void)
{
int r = CRYPTO_set_mem_ex_functions(tor_malloc_, tor_realloc_, tor_free_);
return r ? 0 : -1;
}
#endif /* defined(USE_DMALLOC) */
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