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Support Keymaster 2 configuration and key upgrading

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Bug: 27212248
Change-Id: I96bd9a442f4f535ba6ea44c9e81bcc1fee0ec471
This commit is contained in:
Paul Crowley 2016-05-16 08:14:56 -07:00
parent 0fe14bdd1c
commit dff8c727c1
4 changed files with 149 additions and 88 deletions
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3
Android.mk
View file

@ -38,8 +38,6 @@ common_c_includes := \
external/scrypt/lib/crypto \
frameworks/native/include \
system/security/keystore \
hardware/libhardware/include/hardware \
system/security/softkeymaster/include/keymaster
common_shared_libraries := \
libsysutils \
@ -58,6 +56,7 @@ common_shared_libraries := \
libhardware \
libsoftkeymaster \
libbase \
libsoftkeymasterdevice \
libkeymaster_messages \
common_static_libraries := \

125
KeyStorage.cpp
View file

@ -23,6 +23,7 @@
#include <vector>
#include <errno.h>
#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
@ -66,6 +67,7 @@ static const char* kStretch_nopassword = "nopassword";
static const std::string kStretchPrefix_scrypt = "scrypt ";
static const char* kFn_encrypted_key = "encrypted_key";
static const char* kFn_keymaster_key_blob = "keymaster_key_blob";
static const char* kFn_keymaster_key_blob_upgraded = "keymaster_key_blob_upgraded";
static const char* kFn_salt = "salt";
static const char* kFn_secdiscardable = "secdiscardable";
static const char* kFn_stretching = "stretching";
@ -122,7 +124,7 @@ static bool generateKeymasterKey(Keymaster& keymaster, const KeyAuthentication&
return keymaster.generateKey(paramBuilder.build(), key);
}
static keymaster::AuthorizationSetBuilder beginParams(const KeyAuthentication& auth,
static keymaster::AuthorizationSet beginParams(const KeyAuthentication& auth,
const std::string& appId) {
auto paramBuilder = keymaster::AuthorizationSetBuilder()
.Authorization(keymaster::TAG_BLOCK_MODE, KM_MODE_GCM)
@ -133,45 +135,7 @@ static keymaster::AuthorizationSetBuilder beginParams(const KeyAuthentication& a
LOG(DEBUG) << "Supplying auth token to Keymaster";
addStringParam(&paramBuilder, keymaster::TAG_AUTH_TOKEN, auth.token);
}
return paramBuilder;
}
static bool encryptWithKeymasterKey(Keymaster& keymaster, const std::string& key,
const KeyAuthentication& auth, const std::string& appId,
const std::string& message, std::string* ciphertext) {
auto params = beginParams(auth, appId).build();
keymaster::AuthorizationSet outParams;
auto opHandle = keymaster.begin(KM_PURPOSE_ENCRYPT, key, params, &outParams);
if (!opHandle) return false;
keymaster_blob_t nonceBlob;
if (!outParams.GetTagValue(keymaster::TAG_NONCE, &nonceBlob)) {
LOG(ERROR) << "GCM encryption but no nonce generated";
return false;
}
// nonceBlob here is just a pointer into existing data, must not be freed
std::string nonce(reinterpret_cast<const char*>(nonceBlob.data), nonceBlob.data_length);
if (!checkSize("nonce", nonce.size(), GCM_NONCE_BYTES)) return false;
std::string body;
if (!opHandle.updateCompletely(message, &body)) return false;
std::string mac;
if (!opHandle.finishWithOutput(&mac)) return false;
if (!checkSize("mac", mac.size(), GCM_MAC_BYTES)) return false;
*ciphertext = nonce + body + mac;
return true;
}
static bool decryptWithKeymasterKey(Keymaster& keymaster, const std::string& key,
const KeyAuthentication& auth, const std::string& appId,
const std::string& ciphertext, std::string* message) {
auto nonce = ciphertext.substr(0, GCM_NONCE_BYTES);
auto bodyAndMac = ciphertext.substr(GCM_NONCE_BYTES);
auto params = addStringParam(beginParams(auth, appId), keymaster::TAG_NONCE, nonce).build();
auto opHandle = keymaster.begin(KM_PURPOSE_DECRYPT, key, params);
if (!opHandle) return false;
if (!opHandle.updateCompletely(bodyAndMac, message)) return false;
if (!opHandle.finish()) return false;
return true;
return paramBuilder.build();
}
static bool readFileToString(const std::string& filename, std::string* result) {
@ -190,6 +154,79 @@ static bool writeStringToFile(const std::string& payload, const std::string& fil
return true;
}
static KeymasterOperation begin(Keymaster& keymaster, const std::string& dir,
keymaster_purpose_t purpose,
const keymaster::AuthorizationSet &keyParams,
const keymaster::AuthorizationSet &opParams,
keymaster::AuthorizationSet* outParams) {
auto kmKeyPath = dir + "/" + kFn_keymaster_key_blob;
std::string kmKey;
if (!readFileToString(kmKeyPath, &kmKey)) return KeymasterOperation();
keymaster::AuthorizationSet inParams;
inParams.push_back(keyParams);
inParams.push_back(opParams);
for (;;) {
auto opHandle = keymaster.begin(purpose, kmKey, inParams, outParams);
if (opHandle) {
return opHandle;
}
if (opHandle.error() != KM_ERROR_KEY_REQUIRES_UPGRADE) return opHandle;
LOG(DEBUG) << "Upgrading key: " << dir;
std::string newKey;
if (!keymaster.upgradeKey(kmKey, keyParams, &newKey)) return KeymasterOperation();
auto newKeyPath = dir + "/" + kFn_keymaster_key_blob_upgraded;
if (!writeStringToFile(newKey, newKeyPath)) return KeymasterOperation();
if (rename(newKeyPath.c_str(), kmKeyPath.c_str()) != 0) {
PLOG(ERROR) << "Unable to move upgraded key to location: " << kmKeyPath;
return KeymasterOperation();
}
if (!keymaster.deleteKey(kmKey)) {
LOG(ERROR) << "Key deletion failed during upgrade, continuing anyway: " << dir;
}
kmKey = newKey;
LOG(INFO) << "Key upgraded: " << dir;
}
}
static bool encryptWithKeymasterKey(Keymaster& keymaster, const std::string& dir,
const keymaster::AuthorizationSet &keyParams,
const std::string& message, std::string* ciphertext) {
keymaster::AuthorizationSet opParams;
keymaster::AuthorizationSet outParams;
auto opHandle = begin(keymaster, dir, KM_PURPOSE_ENCRYPT, keyParams, opParams, &outParams);
if (!opHandle) return false;
keymaster_blob_t nonceBlob;
if (!outParams.GetTagValue(keymaster::TAG_NONCE, &nonceBlob)) {
LOG(ERROR) << "GCM encryption but no nonce generated";
return false;
}
// nonceBlob here is just a pointer into existing data, must not be freed
std::string nonce(reinterpret_cast<const char*>(nonceBlob.data), nonceBlob.data_length);
if (!checkSize("nonce", nonce.size(), GCM_NONCE_BYTES)) return false;
std::string body;
if (!opHandle.updateCompletely(message, &body)) return false;
std::string mac;
if (!opHandle.finish(&mac)) return false;
if (!checkSize("mac", mac.size(), GCM_MAC_BYTES)) return false;
*ciphertext = nonce + body + mac;
return true;
}
static bool decryptWithKeymasterKey(Keymaster& keymaster, const std::string& dir,
const keymaster::AuthorizationSet &keyParams,
const std::string& ciphertext, std::string* message) {
auto nonce = ciphertext.substr(0, GCM_NONCE_BYTES);
auto bodyAndMac = ciphertext.substr(GCM_NONCE_BYTES);
auto opParams = addStringParam(keymaster::AuthorizationSetBuilder(),
keymaster::TAG_NONCE, nonce).build();
auto opHandle = begin(keymaster, dir, KM_PURPOSE_DECRYPT, keyParams, opParams, nullptr);
if (!opHandle) return false;
if (!opHandle.updateCompletely(bodyAndMac, message)) return false;
if (!opHandle.finish(nullptr)) return false;
return true;
}
static std::string getStretching() {
char paramstr[PROPERTY_VALUE_MAX];
@ -273,8 +310,9 @@ bool storeKey(const std::string& dir, const KeyAuthentication& auth, const std::
std::string kmKey;
if (!generateKeymasterKey(keymaster, auth, appId, &kmKey)) return false;
if (!writeStringToFile(kmKey, dir + "/" + kFn_keymaster_key_blob)) return false;
auto keyParams = beginParams(auth, appId);
std::string encryptedKey;
if (!encryptWithKeymasterKey(keymaster, kmKey, auth, appId, key, &encryptedKey)) return false;
if (!encryptWithKeymasterKey(keymaster, dir, keyParams, key, &encryptedKey)) return false;
if (!writeStringToFile(encryptedKey, dir + "/" + kFn_encrypted_key)) return false;
return true;
}
@ -296,13 +334,12 @@ bool retrieveKey(const std::string& dir, const KeyAuthentication& auth, std::str
}
std::string appId;
if (!generateAppId(auth, stretching, salt, secdiscardable, &appId)) return false;
std::string kmKey;
if (!readFileToString(dir + "/" + kFn_keymaster_key_blob, &kmKey)) return false;
std::string encryptedMessage;
if (!readFileToString(dir + "/" + kFn_encrypted_key, &encryptedMessage)) return false;
Keymaster keymaster;
if (!keymaster) return false;
return decryptWithKeymasterKey(keymaster, kmKey, auth, appId, encryptedMessage, key);
auto keyParams = beginParams(auth, appId);
return decryptWithKeymasterKey(keymaster, dir, keyParams, encryptedMessage, key);
}
static bool deleteKey(const std::string& dir) {

69
Keymaster.cpp
View file

@ -20,6 +20,7 @@
#include <hardware/hardware.h>
#include <hardware/keymaster1.h>
#include <hardware/keymaster2.h>
#include <keymaster/keymaster_configuration.h>
namespace android {
namespace vold {
@ -31,6 +32,9 @@ class IKeymasterDevice {
virtual keymaster_error_t generate_key(const keymaster_key_param_set_t* params,
keymaster_key_blob_t* key_blob) const = 0;
virtual keymaster_error_t delete_key(const keymaster_key_blob_t* key) const = 0;
virtual keymaster_error_t upgrade_key(const keymaster_key_blob_t* key_to_upgrade,
const keymaster_key_param_set_t* upgrade_params,
keymaster_key_blob_t* upgraded_key) const = 0;
virtual keymaster_error_t begin(keymaster_purpose_t purpose, const keymaster_key_blob_t* key,
const keymaster_key_param_set_t* in_params,
keymaster_key_param_set_t* out_params,
@ -88,6 +92,11 @@ class Keymaster1Device : public KeymasterDevice<keymaster1_device_t> {
public:
explicit Keymaster1Device(keymaster1_device_t* d) : KeymasterDevice<keymaster1_device_t>{d} {}
~Keymaster1Device() override final { keymaster1_close(mDevice); }
keymaster_error_t upgrade_key(const keymaster_key_blob_t* key_to_upgrade,
const keymaster_key_param_set_t* upgrade_params,
keymaster_key_blob_t* upgraded_key) const override final {
return KM_ERROR_UNIMPLEMENTED;
}
keymaster_error_t finish(keymaster_operation_handle_t operation_handle,
const keymaster_key_param_set_t* in_params,
const keymaster_blob_t* signature,
@ -101,6 +110,11 @@ class Keymaster2Device : public KeymasterDevice<keymaster2_device_t> {
public:
explicit Keymaster2Device(keymaster2_device_t* d) : KeymasterDevice<keymaster2_device_t>{d} {}
~Keymaster2Device() override final { keymaster2_close(mDevice); }
keymaster_error_t upgrade_key(const keymaster_key_blob_t* key_to_upgrade,
const keymaster_key_param_set_t* upgrade_params,
keymaster_key_blob_t* upgraded_key) const override final {
return mDevice->upgrade_key(mDevice, key_to_upgrade, upgrade_params, upgraded_key);
}
keymaster_error_t finish(keymaster_operation_handle_t operation_handle,
const keymaster_key_param_set_t* in_params,
const keymaster_blob_t* signature,
@ -142,26 +156,19 @@ bool KeymasterOperation::updateCompletely(const std::string& input, std::string*
return true;
}
bool KeymasterOperation::finish() {
auto error = mDevice->finish(mOpHandle, nullptr, nullptr, nullptr, nullptr);
mDevice = nullptr;
if (error != KM_ERROR_OK) {
LOG(ERROR) << "finish failed, code " << error;
return false;
}
return true;
}
bool KeymasterOperation::finishWithOutput(std::string* output) {
bool KeymasterOperation::finish(std::string* output) {
keymaster_blob_t outputBlob;
auto error = mDevice->finish(mOpHandle, nullptr, nullptr, nullptr, &outputBlob);
auto error = mDevice->finish(mOpHandle, nullptr, nullptr, nullptr,
output ? &outputBlob : nullptr);
mDevice = nullptr;
if (error != KM_ERROR_OK) {
LOG(ERROR) << "finish failed, code " << error;
return false;
}
if (output) {
output->assign(reinterpret_cast<const char*>(outputBlob.data), outputBlob.data_length);
free(const_cast<uint8_t*>(outputBlob.data));
}
return true;
}
@ -173,6 +180,7 @@ Keymaster::Keymaster() {
LOG(ERROR) << "hw_get_module_by_class returned " << ret;
return;
}
LOG(DEBUG) << "module_api_version is " << module->module_api_version;
if (module->module_api_version == KEYMASTER_MODULE_API_VERSION_1_0) {
keymaster1_device_t* device;
ret = keymaster1_open(module, &device);
@ -188,6 +196,11 @@ Keymaster::Keymaster() {
LOG(ERROR) << "keymaster2_open returned " << ret;
return;
}
auto error = ConfigureDevice(device);
if (error != KM_ERROR_OK) {
LOG(ERROR) << "ConfigureDevice returned " << error;
return;
}
mDevice = std::make_shared<Keymaster2Device>(device);
} else {
LOG(ERROR) << "module_api_version is " << module->module_api_version;
@ -217,31 +230,37 @@ bool Keymaster::deleteKey(const std::string& key) {
return true;
}
bool Keymaster::upgradeKey(const std::string& oldKey, const AuthorizationSet& inParams,
std::string* newKey) {
keymaster_key_blob_t oldKeyBlob{reinterpret_cast<const uint8_t*>(oldKey.data()), oldKey.size()};
keymaster_key_blob_t newKeyBlob;
auto error = mDevice->upgrade_key(&oldKeyBlob, &inParams, &newKeyBlob);
if (error != KM_ERROR_OK) {
LOG(ERROR) << "upgrade_key failed, code " << error;
return false;
}
newKey->assign(reinterpret_cast<const char*>(newKeyBlob.key_material),
newKeyBlob.key_material_size);
free(const_cast<uint8_t*>(newKeyBlob.key_material));
return true;
}
KeymasterOperation Keymaster::begin(keymaster_purpose_t purpose, const std::string& key,
const keymaster::AuthorizationSet& inParams,
keymaster::AuthorizationSet* outParams) {
keymaster_key_blob_t keyBlob{reinterpret_cast<const uint8_t*>(key.data()), key.size()};
keymaster_operation_handle_t mOpHandle;
keymaster_key_param_set_t outParams_set;
auto error = mDevice->begin(purpose, &keyBlob, &inParams, &outParams_set, &mOpHandle);
auto error = mDevice->begin(purpose, &keyBlob, &inParams,
outParams ? &outParams_set : nullptr, &mOpHandle);
if (error != KM_ERROR_OK) {
LOG(ERROR) << "begin failed, code " << error;
return KeymasterOperation(nullptr, mOpHandle);
return KeymasterOperation(error);
}
if (outParams) {
outParams->Clear();
outParams->push_back(outParams_set);
keymaster_free_param_set(&outParams_set);
return KeymasterOperation(mDevice, mOpHandle);
}
KeymasterOperation Keymaster::begin(keymaster_purpose_t purpose, const std::string& key,
const keymaster::AuthorizationSet& inParams) {
keymaster_key_blob_t keyBlob{reinterpret_cast<const uint8_t*>(key.data()), key.size()};
keymaster_operation_handle_t mOpHandle;
auto error = mDevice->begin(purpose, &keyBlob, &inParams, nullptr, &mOpHandle);
if (error != KM_ERROR_OK) {
LOG(ERROR) << "begin failed, code " << error;
return KeymasterOperation(nullptr, mOpHandle);
}
return KeymasterOperation(mDevice, mOpHandle);
}

28
Keymaster.h
View file

@ -45,25 +45,31 @@ class KeymasterOperation {
~KeymasterOperation();
// Is this instance valid? This is false if creation fails, and becomes
// false on finish or if an update fails.
explicit operator bool() { return mDevice != nullptr; }
explicit operator bool() { return mError == KM_ERROR_OK; }
keymaster_error_t error() { return mError; }
// Call "update" repeatedly until all of the input is consumed, and
// concatenate the output. Return true on success.
bool updateCompletely(const std::string& input, std::string* output);
// Finish; pass nullptr for the "output" param.
bool finish();
// Finish and write the output to this string.
bool finishWithOutput(std::string* output);
// Finish and write the output to this string, unless pointer is null.
bool finish(std::string* output);
// Move constructor
KeymasterOperation(KeymasterOperation&& rhs) {
mOpHandle = std::move(rhs.mOpHandle);
mDevice = std::move(rhs.mDevice);
mOpHandle = std::move(rhs.mOpHandle);
mError = std::move(rhs.mError);
}
// Construct an object in an error state for error returns
KeymasterOperation() : KeymasterOperation(KM_ERROR_UNKNOWN_ERROR) {}
private:
KeymasterOperation(std::shared_ptr<IKeymasterDevice> d, keymaster_operation_handle_t h)
: mDevice{d}, mOpHandle{h} {}
: mDevice{d}, mOpHandle{h}, mError {KM_ERROR_OK} {}
KeymasterOperation(keymaster_error_t error)
: mDevice{nullptr}, mOpHandle{static_cast<keymaster_operation_handle_t>(0)},
mError {error} {}
std::shared_ptr<IKeymasterDevice> mDevice;
keymaster_operation_handle_t mOpHandle;
keymaster_error_t mError;
DISALLOW_COPY_AND_ASSIGN(KeymasterOperation);
friend class Keymaster;
};
@ -79,12 +85,12 @@ class Keymaster {
bool generateKey(const AuthorizationSet& inParams, std::string* key);
// If the keymaster supports it, permanently delete a key.
bool deleteKey(const std::string& key);
// Begin a new cryptographic operation, collecting output parameters.
// Replace stored key blob in response to KM_ERROR_KEY_REQUIRES_UPGRADE.
bool upgradeKey(const std::string& oldKey, const AuthorizationSet& inParams,
std::string* newKey);
// Begin a new cryptographic operation, collecting output parameters if pointer is non-null
KeymasterOperation begin(keymaster_purpose_t purpose, const std::string& key,
const AuthorizationSet& inParams, AuthorizationSet* outParams);
// Begin a new cryptographic operation; don't collect output parameters.
KeymasterOperation begin(keymaster_purpose_t purpose, const std::string& key,
const AuthorizationSet& inParams);
private:
std::shared_ptr<IKeymasterDevice> mDevice;