9eb9295d78
This change tweaks things as needed so that the code will compile against both the BoringSSL that's currently in Android and a version from upstream. The BORINGSSL_201509 define is temporary to allow the switch to happen without breaking the build and a followup change will remove it. Change-Id: I3d09b5644661353723803bcbda937d34455849a5
456 lines
14 KiB
C++
456 lines
14 KiB
C++
/* Copyright 2014 The Android Open Source Project
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
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#include <UniquePtr.h>
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#include <sys/socket.h>
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#include <stdarg.h>
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#include <string.h>
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#include <unistd.h>
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#include <openssl/bn.h>
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#include <openssl/ec.h>
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#include <openssl/ec_key.h>
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#include <openssl/ecdsa.h>
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#include <openssl/engine.h>
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#include <openssl/evp.h>
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#include <openssl/rsa.h>
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#include <openssl/x509.h>
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#include <binder/IServiceManager.h>
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#include <keystore/keystore.h>
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#include <keystore/IKeystoreService.h>
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using namespace android;
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namespace {
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extern const RSA_METHOD keystore_rsa_method;
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extern const ECDSA_METHOD keystore_ecdsa_method;
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/* key_id_dup is called when one of the RSA or EC_KEY objects is duplicated. */
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int key_id_dup(CRYPTO_EX_DATA* /* to */,
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const CRYPTO_EX_DATA* /* from */,
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void** from_d,
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int /* index */,
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long /* argl */,
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void* /* argp */) {
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char *key_id = reinterpret_cast<char *>(*from_d);
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if (key_id != NULL) {
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*from_d = strdup(key_id);
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}
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return 1;
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}
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/* key_id_free is called when one of the RSA, DSA or EC_KEY object is freed. */
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void key_id_free(void* /* parent */,
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void* ptr,
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CRYPTO_EX_DATA* /* ad */,
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int /* index */,
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long /* argl */,
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void* /* argp */) {
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char *key_id = reinterpret_cast<char *>(ptr);
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free(key_id);
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}
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/* KeystoreEngine is a BoringSSL ENGINE that implements RSA and ECDSA by
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* forwarding the requested operations to Keystore. */
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class KeystoreEngine {
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public:
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KeystoreEngine()
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: rsa_index_(RSA_get_ex_new_index(0 /* argl */,
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NULL /* argp */,
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NULL /* new_func */,
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key_id_dup,
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key_id_free)),
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ec_key_index_(EC_KEY_get_ex_new_index(0 /* argl */,
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NULL /* argp */,
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NULL /* new_func */,
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key_id_dup,
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key_id_free)),
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engine_(ENGINE_new()) {
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ENGINE_set_RSA_method(
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engine_, &keystore_rsa_method, sizeof(keystore_rsa_method));
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ENGINE_set_ECDSA_method(
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engine_, &keystore_ecdsa_method, sizeof(keystore_ecdsa_method));
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}
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int rsa_ex_index() const { return rsa_index_; }
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int ec_key_ex_index() const { return ec_key_index_; }
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const ENGINE* engine() const { return engine_; }
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private:
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const int rsa_index_;
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const int ec_key_index_;
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ENGINE* const engine_;
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};
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pthread_once_t g_keystore_engine_once = PTHREAD_ONCE_INIT;
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KeystoreEngine *g_keystore_engine;
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/* init_keystore_engine is called to initialize |g_keystore_engine|. This
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* should only be called by |pthread_once|. */
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void init_keystore_engine() {
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g_keystore_engine = new KeystoreEngine;
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}
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/* ensure_keystore_engine ensures that |g_keystore_engine| is pointing to a
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* valid |KeystoreEngine| object and creates one if not. */
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void ensure_keystore_engine() {
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pthread_once(&g_keystore_engine_once, init_keystore_engine);
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}
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/* Many OpenSSL APIs take ownership of an argument on success but don't free
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* the argument on failure. This means we need to tell our scoped pointers when
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* we've transferred ownership, without triggering a warning by not using the
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* result of release(). */
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#define OWNERSHIP_TRANSFERRED(obj) \
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typeof (obj.release()) _dummy __attribute__((unused)) = obj.release()
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const char* rsa_get_key_id(const RSA* rsa) {
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return reinterpret_cast<char*>(
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RSA_get_ex_data(rsa, g_keystore_engine->rsa_ex_index()));
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}
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/* rsa_private_transform takes a big-endian integer from |in|, calculates the
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* d'th power of it, modulo the RSA modulus, and writes the result as a
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* big-endian integer to |out|. Both |in| and |out| are |len| bytes long. It
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* returns one on success and zero otherwise. */
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int rsa_private_transform(RSA *rsa, uint8_t *out, const uint8_t *in, size_t len) {
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ALOGV("rsa_private_transform(%p, %p, %p, %u)", rsa, out, in, (unsigned) len);
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const char *key_id = rsa_get_key_id(rsa);
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if (key_id == NULL) {
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ALOGE("key had no key_id!");
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return 0;
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}
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sp<IServiceManager> sm = defaultServiceManager();
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sp<IBinder> binder = sm->getService(String16("android.security.keystore"));
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sp<IKeystoreService> service = interface_cast<IKeystoreService>(binder);
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if (service == NULL) {
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ALOGE("could not contact keystore");
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return 0;
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}
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uint8_t* reply = NULL;
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size_t reply_len;
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int32_t ret = service->sign(String16(key_id), in, len, &reply, &reply_len);
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if (ret < 0) {
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ALOGW("There was an error during rsa_decrypt: could not connect");
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return 0;
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} else if (ret != 0) {
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ALOGW("Error during sign from keystore: %d", ret);
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return 0;
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} else if (reply_len == 0) {
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ALOGW("No valid signature returned");
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free(reply);
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return 0;
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}
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if (reply_len > len) {
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/* The result of the RSA operation can never be larger than the size of
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* the modulus so we assume that the result has extra zeros on the
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* left. This provides attackers with an oracle, but there's nothing
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* that we can do about it here. */
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memcpy(out, reply + reply_len - len, len);
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} else if (reply_len < len) {
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/* If the Keystore implementation returns a short value we assume that
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* it's because it removed leading zeros from the left side. This is
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* bad because it provides attackers with an oracle but we cannot do
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* anything about a broken Keystore implementation here. */
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memset(out, 0, len);
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memcpy(out + len - reply_len, reply, reply_len);
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} else {
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memcpy(out, reply, len);
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}
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free(reply);
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ALOGV("rsa=%p keystore_rsa_priv_dec successful", rsa);
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return 1;
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}
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const struct rsa_meth_st keystore_rsa_method = {
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{
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0 /* references */,
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1 /* is_static */,
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},
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NULL /* app_data */,
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NULL /* init */,
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NULL /* finish */,
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NULL /* size */,
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NULL /* sign */,
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NULL /* verify */,
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NULL /* encrypt */,
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NULL /* sign_raw */,
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NULL /* decrypt */,
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NULL /* verify_raw */,
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rsa_private_transform,
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NULL /* mod_exp */,
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NULL /* bn_mod_exp */,
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RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_OPAQUE | RSA_FLAG_EXT_PKEY,
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NULL /* keygen */,
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#if defined(BORINGSSL_201509)
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NULL /* multi_prime_keygen */,
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#endif
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NULL /* supports_digest */,
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};
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const char* ecdsa_get_key_id(const EC_KEY* ec_key) {
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return reinterpret_cast<char*>(
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EC_KEY_get_ex_data(ec_key, g_keystore_engine->ec_key_ex_index()));
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}
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/* ecdsa_sign signs |digest_len| bytes from |digest| with |ec_key| and writes
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* the resulting signature (an ASN.1 encoded blob) to |sig|. It returns one on
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* success and zero otherwise. */
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static int ecdsa_sign(const uint8_t* digest, size_t digest_len, uint8_t* sig,
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unsigned int* sig_len, EC_KEY* ec_key) {
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ALOGV("ecdsa_sign(%p, %u, %p)", digest, (unsigned) digest_len, ec_key);
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const char *key_id = ecdsa_get_key_id(ec_key);
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if (key_id == NULL) {
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ALOGE("key had no key_id!");
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return 0;
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}
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sp<IServiceManager> sm = defaultServiceManager();
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sp<IBinder> binder = sm->getService(String16("android.security.keystore"));
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sp<IKeystoreService> service = interface_cast<IKeystoreService>(binder);
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if (service == NULL) {
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ALOGE("could not contact keystore");
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return 0;
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}
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size_t ecdsa_size = ECDSA_size(ec_key);
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uint8_t* reply = NULL;
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size_t reply_len;
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int32_t ret = service->sign(String16(reinterpret_cast<const char*>(key_id)),
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digest, digest_len, &reply, &reply_len);
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if (ret < 0) {
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ALOGW("There was an error during ecdsa_sign: could not connect");
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return 0;
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} else if (ret != 0) {
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ALOGW("Error during sign from keystore: %d", ret);
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return 0;
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} else if (reply_len == 0) {
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ALOGW("No valid signature returned");
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free(reply);
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return 0;
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} else if (reply_len > ecdsa_size) {
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ALOGW("Signature is too large");
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free(reply);
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return 0;
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}
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memcpy(sig, reply, reply_len);
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*sig_len = reply_len;
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ALOGV("ecdsa_sign(%p, %u, %p) => success", digest, (unsigned)digest_len,
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ec_key);
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return 1;
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}
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const ECDSA_METHOD keystore_ecdsa_method = {
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{
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0 /* references */,
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1 /* is_static */
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} /* common */,
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NULL /* app_data */,
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NULL /* init */,
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NULL /* finish */,
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NULL /* group_order_size */,
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ecdsa_sign,
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NULL /* verify */,
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ECDSA_FLAG_OPAQUE,
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};
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struct EVP_PKEY_Delete {
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void operator()(EVP_PKEY* p) const {
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EVP_PKEY_free(p);
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}
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};
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typedef UniquePtr<EVP_PKEY, EVP_PKEY_Delete> Unique_EVP_PKEY;
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struct RSA_Delete {
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void operator()(RSA* p) const {
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RSA_free(p);
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}
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};
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typedef UniquePtr<RSA, RSA_Delete> Unique_RSA;
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struct EC_KEY_Delete {
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void operator()(EC_KEY* ec) const {
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EC_KEY_free(ec);
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}
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};
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typedef UniquePtr<EC_KEY, EC_KEY_Delete> Unique_EC_KEY;
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/* wrap_rsa returns an |EVP_PKEY| that contains an RSA key where the public
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* part is taken from |public_rsa| and the private operations are forwarded to
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* KeyStore and operate on the key named |key_id|. */
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static EVP_PKEY *wrap_rsa(const char *key_id, const RSA *public_rsa) {
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Unique_RSA rsa(RSA_new_method(g_keystore_engine->engine()));
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if (rsa.get() == NULL) {
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return NULL;
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}
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char *key_id_copy = strdup(key_id);
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if (key_id_copy == NULL) {
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return NULL;
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}
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if (!RSA_set_ex_data(rsa.get(), g_keystore_engine->rsa_ex_index(),
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key_id_copy)) {
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free(key_id_copy);
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return NULL;
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}
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rsa->n = BN_dup(public_rsa->n);
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rsa->e = BN_dup(public_rsa->e);
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if (rsa->n == NULL || rsa->e == NULL) {
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return NULL;
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}
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Unique_EVP_PKEY result(EVP_PKEY_new());
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if (result.get() == NULL ||
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!EVP_PKEY_assign_RSA(result.get(), rsa.get())) {
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return NULL;
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}
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OWNERSHIP_TRANSFERRED(rsa);
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return result.release();
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}
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/* wrap_ecdsa returns an |EVP_PKEY| that contains an ECDSA key where the public
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* part is taken from |public_rsa| and the private operations are forwarded to
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* KeyStore and operate on the key named |key_id|. */
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static EVP_PKEY *wrap_ecdsa(const char *key_id, const EC_KEY *public_ecdsa) {
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Unique_EC_KEY ec(EC_KEY_new_method(g_keystore_engine->engine()));
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if (ec.get() == NULL) {
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return NULL;
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}
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if (!EC_KEY_set_group(ec.get(), EC_KEY_get0_group(public_ecdsa)) ||
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!EC_KEY_set_public_key(ec.get(), EC_KEY_get0_public_key(public_ecdsa))) {
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return NULL;
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}
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char *key_id_copy = strdup(key_id);
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if (key_id_copy == NULL) {
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return NULL;
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}
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if (!EC_KEY_set_ex_data(ec.get(), g_keystore_engine->ec_key_ex_index(),
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key_id_copy)) {
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free(key_id_copy);
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return NULL;
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}
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Unique_EVP_PKEY result(EVP_PKEY_new());
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if (result.get() == NULL ||
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!EVP_PKEY_assign_EC_KEY(result.get(), ec.get())) {
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return NULL;
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}
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OWNERSHIP_TRANSFERRED(ec);
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return result.release();
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}
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} /* anonymous namespace */
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extern "C" {
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EVP_PKEY* EVP_PKEY_from_keystore(const char* key_id) __attribute__((visibility("default")));
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/* EVP_PKEY_from_keystore returns an |EVP_PKEY| that contains either an RSA or
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* ECDSA key where the public part of the key reflects the value of the key
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* named |key_id| in Keystore and the private operations are forwarded onto
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* KeyStore. */
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EVP_PKEY* EVP_PKEY_from_keystore(const char* key_id) {
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ALOGV("EVP_PKEY_from_keystore(\"%s\")", key_id);
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sp<IServiceManager> sm = defaultServiceManager();
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sp<IBinder> binder = sm->getService(String16("android.security.keystore"));
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sp<IKeystoreService> service = interface_cast<IKeystoreService>(binder);
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if (service == NULL) {
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ALOGE("could not contact keystore");
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return 0;
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}
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uint8_t *pubkey = NULL;
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size_t pubkey_len;
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int32_t ret = service->get_pubkey(String16(key_id), &pubkey, &pubkey_len);
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if (ret < 0) {
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ALOGW("could not contact keystore");
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return NULL;
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} else if (ret != 0) {
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ALOGW("keystore reports error: %d", ret);
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return NULL;
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}
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const uint8_t *inp = pubkey;
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Unique_EVP_PKEY pkey(d2i_PUBKEY(NULL, &inp, pubkey_len));
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free(pubkey);
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if (pkey.get() == NULL) {
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ALOGW("Cannot convert pubkey");
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return NULL;
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}
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ensure_keystore_engine();
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EVP_PKEY *result;
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switch (EVP_PKEY_type(pkey->type)) {
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case EVP_PKEY_RSA: {
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Unique_RSA public_rsa(EVP_PKEY_get1_RSA(pkey.get()));
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result = wrap_rsa(key_id, public_rsa.get());
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break;
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}
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case EVP_PKEY_EC: {
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Unique_EC_KEY public_ecdsa(EVP_PKEY_get1_EC_KEY(pkey.get()));
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result = wrap_ecdsa(key_id, public_ecdsa.get());
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break;
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}
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default:
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ALOGE("Unsupported key type %d", EVP_PKEY_type(pkey->type));
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result = NULL;
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}
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return result;
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}
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} // extern "C"
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