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/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <errno.h>
#include <string.h>
#include <stdint.h>
#include <keystore/keystore.h>
#include <hardware/hardware.h>
#include <hardware/keymaster.h>
#include <openssl/evp.h>
#include <openssl/bio.h>
#include <openssl/rsa.h>
#include <openssl/err.h>
#include <openssl/x509.h>
#include <utils/UniquePtr.h>
// For debugging
//#define LOG_NDEBUG 0
#define LOG_TAG "OpenSSLKeyMaster"
#include <cutils/log.h>
struct BIGNUM_Delete {
void operator()(BIGNUM* p) const {
BN_free(p);
}
};
typedef UniquePtr<BIGNUM, BIGNUM_Delete> Unique_BIGNUM;
struct EVP_PKEY_Delete {
void operator()(EVP_PKEY* p) const {
EVP_PKEY_free(p);
}
};
typedef UniquePtr<EVP_PKEY, EVP_PKEY_Delete> Unique_EVP_PKEY;
struct PKCS8_PRIV_KEY_INFO_Delete {
void operator()(PKCS8_PRIV_KEY_INFO* p) const {
PKCS8_PRIV_KEY_INFO_free(p);
}
};
typedef UniquePtr<PKCS8_PRIV_KEY_INFO, PKCS8_PRIV_KEY_INFO_Delete> Unique_PKCS8_PRIV_KEY_INFO;
struct RSA_Delete {
void operator()(RSA* p) const {
RSA_free(p);
}
};
typedef UniquePtr<RSA, RSA_Delete> Unique_RSA;
typedef UniquePtr<keymaster_device_t> Unique_keymaster_device_t;
/**
* Many OpenSSL APIs take ownership of an argument on success but don't free the argument
* on failure. This means we need to tell our scoped pointers when we've transferred ownership,
* without triggering a warning by not using the result of release().
*/
#define OWNERSHIP_TRANSFERRED(obj) \
typeof (obj.release()) _dummy __attribute__((unused)) = obj.release()
/*
* Checks this thread's OpenSSL error queue and logs if
* necessary.
*/
static void logOpenSSLError(const char* location) {
int error = ERR_get_error();
if (error != 0) {
char message[256];
ERR_error_string_n(error, message, sizeof(message));
ALOGE("OpenSSL error in %s %d: %s", location, error, message);
}
ERR_clear_error();
ERR_remove_state(0);
}
static int wrap_key(EVP_PKEY* pkey, int type, uint8_t** keyBlob, size_t* keyBlobLength) {
/* Find the length of each size */
int publicLen = i2d_PublicKey(pkey, NULL);
int privateLen = i2d_PrivateKey(pkey, NULL);
if (privateLen <= 0 || publicLen <= 0) {
ALOGE("private or public key size was too big");
return -1;
}
/* int type + int size + private key data + int size + public key data */
*keyBlobLength = get_softkey_header_size() + sizeof(int) + sizeof(int) + privateLen
+ sizeof(int) + publicLen;
UniquePtr<unsigned char[]> derData(new unsigned char[*keyBlobLength]);
if (derData.get() == NULL) {
ALOGE("could not allocate memory for key blob");
return -1;
}
unsigned char* p = derData.get();
/* Write the magic value for software keys. */
p = add_softkey_header(p, *keyBlobLength);
/* Write key type to allocated buffer */
for (int i = sizeof(int) - 1; i >= 0; i--) {
*p++ = (type >> (8*i)) & 0xFF;
}
/* Write public key to allocated buffer */
for (int i = sizeof(int) - 1; i >= 0; i--) {
*p++ = (publicLen >> (8*i)) & 0xFF;
}
if (i2d_PublicKey(pkey, &p) != publicLen) {
logOpenSSLError("wrap_key");
return -1;
}
/* Write private key to allocated buffer */
for (int i = sizeof(int) - 1; i >= 0; i--) {
*p++ = (privateLen >> (8*i)) & 0xFF;
}
if (i2d_PrivateKey(pkey, &p) != privateLen) {
logOpenSSLError("wrap_key");
return -1;
}
*keyBlob = derData.release();
return 0;
}
static EVP_PKEY* unwrap_key(const uint8_t* keyBlob, const size_t keyBlobLength) {
long publicLen = 0;
long privateLen = 0;
const uint8_t* p = keyBlob;
const uint8_t *const end = keyBlob + keyBlobLength;
if (keyBlob == NULL) {
ALOGE("supplied key blob was NULL");
return NULL;
}
// Should be large enough for:
// int32 magic, int32 type, int32 pubLen, char* pub, int32 privLen, char* priv
if (keyBlobLength < (get_softkey_header_size() + sizeof(int) + sizeof(int) + 1
+ sizeof(int) + 1)) {
ALOGE("key blob appears to be truncated");
return NULL;
}
if (!is_softkey(p, keyBlobLength)) {
ALOGE("cannot read key; it was not made by this keymaster");
return NULL;
}
p += get_softkey_header_size();
int type = 0;
for (size_t i = 0; i < sizeof(int); i++) {
type = (type << 8) | *p++;
}
Unique_EVP_PKEY pkey(EVP_PKEY_new());
if (pkey.get() == NULL) {
logOpenSSLError("unwrap_key");
return NULL;
}
for (size_t i = 0; i < sizeof(int); i++) {
publicLen = (publicLen << 8) | *p++;
}
if (p + publicLen > end) {
ALOGE("public key length encoding error: size=%ld, end=%d", publicLen, end - p);
return NULL;
}
EVP_PKEY* tmp = pkey.get();
d2i_PublicKey(type, &tmp, &p, publicLen);
if (end - p < 2) {
ALOGE("private key truncated");
return NULL;
}
for (size_t i = 0; i < sizeof(int); i++) {
privateLen = (privateLen << 8) | *p++;
}
if (p + privateLen > end) {
ALOGE("private key length encoding error: size=%ld, end=%d", privateLen, end - p);
return NULL;
}
d2i_PrivateKey(type, &tmp, &p, privateLen);
return pkey.release();
}
static int openssl_generate_keypair(const keymaster_device_t* dev,
const keymaster_keypair_t key_type, const void* key_params,
uint8_t** keyBlob, size_t* keyBlobLength) {
ssize_t privateLen, publicLen;
if (key_type != TYPE_RSA) {
ALOGW("Unsupported key type %d", key_type);
return -1;
} else if (key_params == NULL) {
ALOGW("key_params == null");
return -1;
}
keymaster_rsa_keygen_params_t* rsa_params = (keymaster_rsa_keygen_params_t*) key_params;
Unique_BIGNUM bn(BN_new());
if (bn.get() == NULL) {
logOpenSSLError("openssl_generate_keypair");
return -1;
}
if (BN_set_word(bn.get(), rsa_params->public_exponent) == 0) {
logOpenSSLError("openssl_generate_keypair");
return -1;
}
/* initialize RSA */
Unique_RSA rsa(RSA_new());
if (rsa.get() == NULL) {
logOpenSSLError("openssl_generate_keypair");
return -1;
}
if (!RSA_generate_key_ex(rsa.get(), rsa_params->modulus_size, bn.get(), NULL)
|| RSA_check_key(rsa.get()) < 0) {
logOpenSSLError("openssl_generate_keypair");
return -1;
}
/* assign to EVP */
Unique_EVP_PKEY pkey(EVP_PKEY_new());
if (pkey.get() == NULL) {
logOpenSSLError("openssl_generate_keypair");
return -1;
}
if (EVP_PKEY_assign_RSA(pkey.get(), rsa.get()) == 0) {
logOpenSSLError("openssl_generate_keypair");
return -1;
}
OWNERSHIP_TRANSFERRED(rsa);
if (wrap_key(pkey.get(), EVP_PKEY_RSA, keyBlob, keyBlobLength)) {
return -1;
}
return 0;
}
static int openssl_import_keypair(const keymaster_device_t* dev,
const uint8_t* key, const size_t key_length,
uint8_t** key_blob, size_t* key_blob_length) {
int response = -1;
if (key == NULL) {
ALOGW("input key == NULL");
return -1;
} else if (key_blob == NULL || key_blob_length == NULL) {
ALOGW("output key blob or length == NULL");
return -1;
}
Unique_PKCS8_PRIV_KEY_INFO pkcs8(d2i_PKCS8_PRIV_KEY_INFO(NULL, &key, key_length));
if (pkcs8.get() == NULL) {
logOpenSSLError("openssl_import_keypair");
return -1;
}
/* assign to EVP */
Unique_EVP_PKEY pkey(EVP_PKCS82PKEY(pkcs8.get()));
if (pkey.get() == NULL) {
logOpenSSLError("openssl_import_keypair");
return -1;
}
OWNERSHIP_TRANSFERRED(pkcs8);
if (wrap_key(pkey.get(), EVP_PKEY_type(pkey->type), key_blob, key_blob_length)) {
return -1;
}
return 0;
}
static int openssl_get_keypair_public(const struct keymaster_device* dev,
const uint8_t* key_blob, const size_t key_blob_length,
uint8_t** x509_data, size_t* x509_data_length) {
if (x509_data == NULL || x509_data_length == NULL) {
ALOGW("output public key buffer == NULL");
return -1;
}
Unique_EVP_PKEY pkey(unwrap_key(key_blob, key_blob_length));
if (pkey.get() == NULL) {
return -1;
}
int len = i2d_PUBKEY(pkey.get(), NULL);
if (len <= 0) {
logOpenSSLError("openssl_get_keypair_public");
return -1;
}
UniquePtr<uint8_t> key(static_cast<uint8_t*>(malloc(len)));
if (key.get() == NULL) {
ALOGE("Could not allocate memory for public key data");
return -1;
}
unsigned char* tmp = reinterpret_cast<unsigned char*>(key.get());
if (i2d_PUBKEY(pkey.get(), &tmp) != len) {
logOpenSSLError("openssl_get_keypair_public");
return -1;
}
ALOGV("Length of x509 data is %d", len);
*x509_data_length = len;
*x509_data = key.release();
return 0;
}
static int openssl_sign_data(const keymaster_device_t* dev,
const void* params,
const uint8_t* keyBlob, const size_t keyBlobLength,
const uint8_t* data, const size_t dataLength,
uint8_t** signedData, size_t* signedDataLength) {
int result = -1;
EVP_MD_CTX ctx;
size_t maxSize;
if (data == NULL) {
ALOGW("input data to sign == NULL");
return -1;
} else if (signedData == NULL || signedDataLength == NULL) {
ALOGW("output signature buffer == NULL");
return -1;
}
Unique_EVP_PKEY pkey(unwrap_key(keyBlob, keyBlobLength));
if (pkey.get() == NULL) {
return -1;
}
if (EVP_PKEY_type(pkey->type) != EVP_PKEY_RSA) {
ALOGW("Cannot handle non-RSA keys yet");
return -1;
}
keymaster_rsa_sign_params_t* sign_params = (keymaster_rsa_sign_params_t*) params;
if (sign_params->digest_type != DIGEST_NONE) {
ALOGW("Cannot handle digest type %d", sign_params->digest_type);
return -1;
} else if (sign_params->padding_type != PADDING_NONE) {
ALOGW("Cannot handle padding type %d", sign_params->padding_type);
return -1;
}
Unique_RSA rsa(EVP_PKEY_get1_RSA(pkey.get()));
if (rsa.get() == NULL) {
logOpenSSLError("openssl_sign_data");
return -1;
}
UniquePtr<uint8_t> signedDataPtr(reinterpret_cast<uint8_t*>(malloc(dataLength)));
if (signedDataPtr.get() == NULL) {
logOpenSSLError("openssl_sign_data");
return -1;
}
unsigned char* tmp = reinterpret_cast<unsigned char*>(signedDataPtr.get());
if (RSA_private_encrypt(dataLength, data, tmp, rsa.get(), RSA_NO_PADDING) <= 0) {
logOpenSSLError("openssl_sign_data");
return -1;
}
*signedDataLength = dataLength;
*signedData = signedDataPtr.release();
return 0;
}
static int openssl_verify_data(const keymaster_device_t* dev,
const void* params,
const uint8_t* keyBlob, const size_t keyBlobLength,
const uint8_t* signedData, const size_t signedDataLength,
const uint8_t* signature, const size_t signatureLength) {
if (signedData == NULL || signature == NULL) {
ALOGW("data or signature buffers == NULL");
return -1;
}
Unique_EVP_PKEY pkey(unwrap_key(keyBlob, keyBlobLength));
if (pkey.get() == NULL) {
return -1;
}
if (EVP_PKEY_type(pkey->type) != EVP_PKEY_RSA) {
ALOGW("Cannot handle non-RSA keys yet");
return -1;
}
keymaster_rsa_sign_params_t* sign_params = (keymaster_rsa_sign_params_t*) params;
if (sign_params->digest_type != DIGEST_NONE) {
ALOGW("Cannot handle digest type %d", sign_params->digest_type);
return -1;
} else if (sign_params->padding_type != PADDING_NONE) {
ALOGW("Cannot handle padding type %d", sign_params->padding_type);
return -1;
} else if (signatureLength != signedDataLength) {
ALOGW("signed data length must be signature length");
return -1;
}
Unique_RSA rsa(EVP_PKEY_get1_RSA(pkey.get()));
if (rsa.get() == NULL) {
logOpenSSLError("openssl_verify_data");
return -1;
}
UniquePtr<uint8_t> dataPtr(reinterpret_cast<uint8_t*>(malloc(signedDataLength)));
if (dataPtr.get() == NULL) {
logOpenSSLError("openssl_verify_data");
return -1;
}
unsigned char* tmp = reinterpret_cast<unsigned char*>(dataPtr.get());
if (!RSA_public_decrypt(signatureLength, signature, tmp, rsa.get(), RSA_NO_PADDING)) {
logOpenSSLError("openssl_verify_data");
return -1;
}
int result = 0;
for (size_t i = 0; i < signedDataLength; i++) {
result |= tmp[i] ^ signedData[i];
}
return result == 0 ? 0 : -1;
}
/* Close an opened OpenSSL instance */
static int openssl_close(hw_device_t *dev) {
free(dev);
return 0;
}
/*
* Generic device handling
*/
static int openssl_open(const hw_module_t* module, const char* name,
hw_device_t** device) {
if (strcmp(name, KEYSTORE_KEYMASTER) != 0)
return -EINVAL;
Unique_keymaster_device_t dev(new keymaster_device_t);
if (dev.get() == NULL)
return -ENOMEM;
dev->common.tag = HARDWARE_DEVICE_TAG;
dev->common.version = 1;
dev->common.module = (struct hw_module_t*) module;
dev->common.close = openssl_close;
dev->flags = KEYMASTER_SOFTWARE_ONLY;
dev->generate_keypair = openssl_generate_keypair;
dev->import_keypair = openssl_import_keypair;
dev->get_keypair_public = openssl_get_keypair_public;
dev->delete_keypair = NULL;
dev->delete_all = NULL;
dev->sign_data = openssl_sign_data;
dev->verify_data = openssl_verify_data;
ERR_load_crypto_strings();
ERR_load_BIO_strings();
*device = reinterpret_cast<hw_device_t*>(dev.release());
return 0;
}
static struct hw_module_methods_t keystore_module_methods = {
open: openssl_open,
};
struct keystore_module HAL_MODULE_INFO_SYM
__attribute__ ((visibility ("default"))) = {
common: {
tag: HARDWARE_MODULE_TAG,
version_major: 1,
version_minor: 0,
id: KEYSTORE_HARDWARE_MODULE_ID,
name: "Keymaster OpenSSL HAL",
author: "The Android Open Source Project",
methods: &keystore_module_methods,
dso: 0,
reserved: {},
},
};