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ara-mdk / platform / system / security / refs/heads/master / . / keystore / keystore.cpp
blob: 9b08398a1cf228e76d6ac137f5ae69fadbe7175d [file] [log] [blame]
/*
* Copyright (C) 2009 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.
*/
//#define LOG_NDEBUG 0
#define LOG_TAG "keystore"
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <errno.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <assert.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <arpa/inet.h>
#include <openssl/aes.h>
#include <openssl/bio.h>
#include <openssl/evp.h>
#include <openssl/md5.h>
#include <openssl/pem.h>
#include <hardware/keymaster.h>
#include <utils/String8.h>
#include <utils/UniquePtr.h>
#include <utils/Vector.h>
#include <keystore/IKeystoreService.h>
#include <binder/IPCThreadState.h>
#include <binder/IServiceManager.h>
#include <cutils/log.h>
#include <cutils/sockets.h>
#include <private/android_filesystem_config.h>
#include <keystore/keystore.h>
/* KeyStore is a secured storage for key-value pairs. In this implementation,
* each file stores one key-value pair. Keys are encoded in file names, and
* values are encrypted with checksums. The encryption key is protected by a
* user-defined password. To keep things simple, buffers are always larger than
* the maximum space we needed, so boundary checks on buffers are omitted. */
#define KEY_SIZE ((NAME_MAX - 15) / 2)
#define VALUE_SIZE 32768
#define PASSWORD_SIZE VALUE_SIZE
struct BIO_Delete {
void operator()(BIO* p) const {
BIO_free(p);
}
};
typedef UniquePtr<BIO, BIO_Delete> Unique_BIO;
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;
static int keymaster_device_initialize(keymaster_device_t** dev) {
int rc;
const hw_module_t* mod;
rc = hw_get_module_by_class(KEYSTORE_HARDWARE_MODULE_ID, NULL, &mod);
if (rc) {
ALOGE("could not find any keystore module");
goto out;
}
rc = keymaster_open(mod, dev);
if (rc) {
ALOGE("could not open keymaster device in %s (%s)",
KEYSTORE_HARDWARE_MODULE_ID, strerror(-rc));
goto out;
}
return 0;
out:
*dev = NULL;
return rc;
}
static void keymaster_device_release(keymaster_device_t* dev) {
keymaster_close(dev);
}
/***************
* PERMISSIONS *
***************/
/* Here are the permissions, actions, users, and the main function. */
typedef enum {
P_TEST = 1 << 0,
P_GET = 1 << 1,
P_INSERT = 1 << 2,
P_DELETE = 1 << 3,
P_EXIST = 1 << 4,
P_SAW = 1 << 5,
P_RESET = 1 << 6,
P_PASSWORD = 1 << 7,
P_LOCK = 1 << 8,
P_UNLOCK = 1 << 9,
P_ZERO = 1 << 10,
P_SIGN = 1 << 11,
P_VERIFY = 1 << 12,
P_GRANT = 1 << 13,
P_DUPLICATE = 1 << 14,
P_CLEAR_UID = 1 << 15,
} perm_t;
static struct user_euid {
uid_t uid;
uid_t euid;
} user_euids[] = {
{AID_VPN, AID_SYSTEM},
{AID_WIFI, AID_SYSTEM},
{AID_ROOT, AID_SYSTEM},
};
static struct user_perm {
uid_t uid;
perm_t perms;
} user_perms[] = {
{AID_SYSTEM, static_cast<perm_t>((uint32_t)(~0)) },
{AID_VPN, static_cast<perm_t>(P_GET | P_SIGN | P_VERIFY) },
{AID_WIFI, static_cast<perm_t>(P_GET | P_SIGN | P_VERIFY) },
{AID_ROOT, static_cast<perm_t>(P_GET) },
};
static const perm_t DEFAULT_PERMS = static_cast<perm_t>(P_TEST | P_GET | P_INSERT | P_DELETE | P_EXIST | P_SAW | P_SIGN
| P_VERIFY);
/**
* Returns the app ID (in the Android multi-user sense) for the current
* UNIX UID.
*/
static uid_t get_app_id(uid_t uid) {
return uid % AID_USER;
}
/**
* Returns the user ID (in the Android multi-user sense) for the current
* UNIX UID.
*/
static uid_t get_user_id(uid_t uid) {
return uid / AID_USER;
}
static bool has_permission(uid_t uid, perm_t perm) {
// All system users are equivalent for multi-user support.
if (get_app_id(uid) == AID_SYSTEM) {
uid = AID_SYSTEM;
}
for (size_t i = 0; i < sizeof(user_perms)/sizeof(user_perms[0]); i++) {
struct user_perm user = user_perms[i];
if (user.uid == uid) {
return user.perms & perm;
}
}
return DEFAULT_PERMS & perm;
}
/**
* Returns the UID that the callingUid should act as. This is here for
* legacy support of the WiFi and VPN systems and should be removed
* when WiFi can operate in its own namespace.
*/
static uid_t get_keystore_euid(uid_t uid) {
for (size_t i = 0; i < sizeof(user_euids)/sizeof(user_euids[0]); i++) {
struct user_euid user = user_euids[i];
if (user.uid == uid) {
return user.euid;
}
}
return uid;
}
/**
* Returns true if the callingUid is allowed to interact in the targetUid's
* namespace.
*/
static bool is_granted_to(uid_t callingUid, uid_t targetUid) {
for (size_t i = 0; i < sizeof(user_euids)/sizeof(user_euids[0]); i++) {
struct user_euid user = user_euids[i];
if (user.euid == callingUid && user.uid == targetUid) {
return true;
}
}
return false;
}
/* Here is the encoding of keys. This is necessary in order to allow arbitrary
* characters in keys. Characters in [0-~] are not encoded. Others are encoded
* into two bytes. The first byte is one of [+-.] which represents the first
* two bits of the character. The second byte encodes the rest of the bits into
* [0-o]. Therefore in the worst case the length of a key gets doubled. Note
* that Base64 cannot be used here due to the need of prefix match on keys. */
static size_t encode_key_length(const android::String8& keyName) {
const uint8_t* in = reinterpret_cast<const uint8_t*>(keyName.string());
size_t length = keyName.length();
for (int i = length; i > 0; --i, ++in) {
if (*in < '0' || *in > '~') {
++length;
}
}
return length;
}
static int encode_key(char* out, const android::String8& keyName) {
const uint8_t* in = reinterpret_cast<const uint8_t*>(keyName.string());
size_t length = keyName.length();
for (int i = length; i > 0; --i, ++in, ++out) {
if (*in < '0' || *in > '~') {
*out = '+' + (*in >> 6);
*++out = '0' + (*in & 0x3F);
++length;
} else {
*out = *in;
}
}
*out = '\0';
return length;
}
static int encode_key_for_uid(char* out, uid_t uid, const android::String8& keyName) {
int n = snprintf(out, NAME_MAX, "%u_", uid);
out += n;
return n + encode_key(out, keyName);
}
/*
* Converts from the "escaped" format on disk to actual name.
* This will be smaller than the input string.
*
* Characters that should combine with the next at the end will be truncated.
*/
static size_t decode_key_length(const char* in, size_t length) {
size_t outLength = 0;
for (const char* end = in + length; in < end; in++) {
/* This combines with the next character. */
if (*in < '0' || *in > '~') {
continue;
}
outLength++;
}
return outLength;
}
static void decode_key(char* out, const char* in, size_t length) {
for (const char* end = in + length; in < end; in++) {
if (*in < '0' || *in > '~') {
/* Truncate combining characters at the end. */
if (in + 1 >= end) {
break;
}
*out = (*in++ - '+') << 6;
*out++ |= (*in - '0') & 0x3F;
} else {
*out++ = *in;
}
}
*out = '\0';
}
static size_t readFully(int fd, uint8_t* data, size_t size) {
size_t remaining = size;
while (remaining > 0) {
ssize_t n = TEMP_FAILURE_RETRY(read(fd, data, remaining));
if (n <= 0) {
return size - remaining;
}
data += n;
remaining -= n;
}
return size;
}
static size_t writeFully(int fd, uint8_t* data, size_t size) {
size_t remaining = size;
while (remaining > 0) {
ssize_t n = TEMP_FAILURE_RETRY(write(fd, data, remaining));
if (n < 0) {
ALOGW("write failed: %s", strerror(errno));
return size - remaining;
}
data += n;
remaining -= n;
}
return size;
}
class Entropy {
public:
Entropy() : mRandom(-1) {}
~Entropy() {
if (mRandom >= 0) {
close(mRandom);
}
}
bool open() {
const char* randomDevice = "/dev/urandom";
mRandom = TEMP_FAILURE_RETRY(::open(randomDevice, O_RDONLY));
if (mRandom < 0) {
ALOGE("open: %s: %s", randomDevice, strerror(errno));
return false;
}
return true;
}
bool generate_random_data(uint8_t* data, size_t size) const {
return (readFully(mRandom, data, size) == size);
}
private:
int mRandom;
};
/* Here is the file format. There are two parts in blob.value, the secret and
* the description. The secret is stored in ciphertext, and its original size
* can be found in blob.length. The description is stored after the secret in
* plaintext, and its size is specified in blob.info. The total size of the two
* parts must be no more than VALUE_SIZE bytes. The first field is the version,
* the second is the blob's type, and the third byte is flags. Fields other
* than blob.info, blob.length, and blob.value are modified by encryptBlob()
* and decryptBlob(). Thus they should not be accessed from outside. */
/* ** Note to future implementors of encryption: **
* Currently this is the construction:
* metadata || Enc(MD5(data) || data)
*
* This should be the construction used for encrypting if re-implementing:
*
* Derive independent keys for encryption and MAC:
* Kenc = AES_encrypt(masterKey, "Encrypt")
* Kmac = AES_encrypt(masterKey, "MAC")
*
* Store this:
* metadata || AES_CTR_encrypt(Kenc, rand_IV, data) ||
* HMAC(Kmac, metadata || Enc(data))
*/
struct __attribute__((packed)) blob {
uint8_t version;
uint8_t type;
uint8_t flags;
uint8_t info;
uint8_t vector[AES_BLOCK_SIZE];
uint8_t encrypted[0]; // Marks offset to encrypted data.
uint8_t digest[MD5_DIGEST_LENGTH];
uint8_t digested[0]; // Marks offset to digested data.
int32_t length; // in network byte order when encrypted
uint8_t value[VALUE_SIZE + AES_BLOCK_SIZE];
};
typedef enum {
TYPE_ANY = 0, // meta type that matches anything
TYPE_GENERIC = 1,
TYPE_MASTER_KEY = 2,
TYPE_KEY_PAIR = 3,
} BlobType;
static const uint8_t CURRENT_BLOB_VERSION = 2;
class Blob {
public:
Blob(const uint8_t* value, int32_t valueLength, const uint8_t* info, uint8_t infoLength,
BlobType type) {
mBlob.length = valueLength;
memcpy(mBlob.value, value, valueLength);
mBlob.info = infoLength;
memcpy(mBlob.value + valueLength, info, infoLength);
mBlob.version = CURRENT_BLOB_VERSION;
mBlob.type = uint8_t(type);
mBlob.flags = KEYSTORE_FLAG_NONE;
}
Blob(blob b) {
mBlob = b;
}
Blob() {}
const uint8_t* getValue() const {
return mBlob.value;
}
int32_t getLength() const {
return mBlob.length;
}
const uint8_t* getInfo() const {
return mBlob.value + mBlob.length;
}
uint8_t getInfoLength() const {
return mBlob.info;
}
uint8_t getVersion() const {
return mBlob.version;
}
bool isEncrypted() const {
if (mBlob.version < 2) {
return true;
}
return mBlob.flags & KEYSTORE_FLAG_ENCRYPTED;
}
void setEncrypted(bool encrypted) {
if (encrypted) {
mBlob.flags |= KEYSTORE_FLAG_ENCRYPTED;
} else {
mBlob.flags &= ~KEYSTORE_FLAG_ENCRYPTED;
}
}
void setVersion(uint8_t version) {
mBlob.version = version;
}
BlobType getType() const {
return BlobType(mBlob.type);
}
void setType(BlobType type) {
mBlob.type = uint8_t(type);
}
ResponseCode writeBlob(const char* filename, AES_KEY *aes_key, State state, Entropy* entropy) {
ALOGV("writing blob %s", filename);
if (isEncrypted()) {
if (state != STATE_NO_ERROR) {
ALOGD("couldn't insert encrypted blob while not unlocked");
return LOCKED;
}
if (!entropy->generate_random_data(mBlob.vector, AES_BLOCK_SIZE)) {
ALOGW("Could not read random data for: %s", filename);
return SYSTEM_ERROR;
}
}
// data includes the value and the value's length
size_t dataLength = mBlob.length + sizeof(mBlob.length);
// pad data to the AES_BLOCK_SIZE
size_t digestedLength = ((dataLength + AES_BLOCK_SIZE - 1)
/ AES_BLOCK_SIZE * AES_BLOCK_SIZE);
// encrypted data includes the digest value
size_t encryptedLength = digestedLength + MD5_DIGEST_LENGTH;
// move info after space for padding
memmove(&mBlob.encrypted[encryptedLength], &mBlob.value[mBlob.length], mBlob.info);
// zero padding area
memset(mBlob.value + mBlob.length, 0, digestedLength - dataLength);
mBlob.length = htonl(mBlob.length);
if (isEncrypted()) {
MD5(mBlob.digested, digestedLength, mBlob.digest);
uint8_t vector[AES_BLOCK_SIZE];
memcpy(vector, mBlob.vector, AES_BLOCK_SIZE);
AES_cbc_encrypt(mBlob.encrypted, mBlob.encrypted, encryptedLength,
aes_key, vector, AES_ENCRYPT);
}
size_t headerLength = (mBlob.encrypted - (uint8_t*) &mBlob);
size_t fileLength = encryptedLength + headerLength + mBlob.info;
const char* tmpFileName = ".tmp";
int out = TEMP_FAILURE_RETRY(open(tmpFileName,
O_WRONLY | O_TRUNC | O_CREAT, S_IRUSR | S_IWUSR));
if (out < 0) {
ALOGW("could not open file: %s: %s", tmpFileName, strerror(errno));
return SYSTEM_ERROR;
}
size_t writtenBytes = writeFully(out, (uint8_t*) &mBlob, fileLength);
if (close(out) != 0) {
return SYSTEM_ERROR;
}
if (writtenBytes != fileLength) {
ALOGW("blob not fully written %zu != %zu", writtenBytes, fileLength);
unlink(tmpFileName);
return SYSTEM_ERROR;
}
if (rename(tmpFileName, filename) == -1) {
ALOGW("could not rename blob to %s: %s", filename, strerror(errno));
return SYSTEM_ERROR;
}
return NO_ERROR;
}
ResponseCode readBlob(const char* filename, AES_KEY *aes_key, State state) {
ALOGV("reading blob %s", filename);
int in = TEMP_FAILURE_RETRY(open(filename, O_RDONLY));
if (in < 0) {
return (errno == ENOENT) ? KEY_NOT_FOUND : SYSTEM_ERROR;
}
// fileLength may be less than sizeof(mBlob) since the in
// memory version has extra padding to tolerate rounding up to
// the AES_BLOCK_SIZE
size_t fileLength = readFully(in, (uint8_t*) &mBlob, sizeof(mBlob));
if (close(in) != 0) {
return SYSTEM_ERROR;
}
if (isEncrypted() && (state != STATE_NO_ERROR)) {
return LOCKED;
}
size_t headerLength = (mBlob.encrypted - (uint8_t*) &mBlob);
if (fileLength < headerLength) {
return VALUE_CORRUPTED;
}
ssize_t encryptedLength = fileLength - (headerLength + mBlob.info);
if (encryptedLength < 0) {
return VALUE_CORRUPTED;
}
ssize_t digestedLength;
if (isEncrypted()) {
if (encryptedLength % AES_BLOCK_SIZE != 0) {
return VALUE_CORRUPTED;
}
AES_cbc_encrypt(mBlob.encrypted, mBlob.encrypted, encryptedLength, aes_key,
mBlob.vector, AES_DECRYPT);
digestedLength = encryptedLength - MD5_DIGEST_LENGTH;
uint8_t computedDigest[MD5_DIGEST_LENGTH];
MD5(mBlob.digested, digestedLength, computedDigest);
if (memcmp(mBlob.digest, computedDigest, MD5_DIGEST_LENGTH) != 0) {
return VALUE_CORRUPTED;
}
} else {
digestedLength = encryptedLength;
}
ssize_t maxValueLength = digestedLength - sizeof(mBlob.length);
mBlob.length = ntohl(mBlob.length);
if (mBlob.length < 0 || mBlob.length > maxValueLength) {
return VALUE_CORRUPTED;
}
if (mBlob.info != 0) {
// move info from after padding to after data
memmove(&mBlob.value[mBlob.length], &mBlob.value[maxValueLength], mBlob.info);
}
return ::NO_ERROR;
}
private:
struct blob mBlob;
};
class UserState {
public:
UserState(uid_t userId) : mUserId(userId), mRetry(MAX_RETRY) {
asprintf(&mUserDir, "user_%u", mUserId);
asprintf(&mMasterKeyFile, "%s/.masterkey", mUserDir);
}
~UserState() {
free(mUserDir);
free(mMasterKeyFile);
}
bool initialize() {
if ((mkdir(mUserDir, S_IRUSR | S_IWUSR | S_IXUSR) < 0) && (errno != EEXIST)) {
ALOGE("Could not create directory '%s'", mUserDir);
return false;
}
if (access(mMasterKeyFile, R_OK) == 0) {
setState(STATE_LOCKED);
} else {
setState(STATE_UNINITIALIZED);
}
return true;
}
uid_t getUserId() const {
return mUserId;
}
const char* getUserDirName() const {
return mUserDir;
}
const char* getMasterKeyFileName() const {
return mMasterKeyFile;
}
void setState(State state) {
mState = state;
if (mState == STATE_NO_ERROR || mState == STATE_UNINITIALIZED) {
mRetry = MAX_RETRY;
}
}
State getState() const {
return mState;
}
int8_t getRetry() const {
return mRetry;
}
void zeroizeMasterKeysInMemory() {
memset(mMasterKey, 0, sizeof(mMasterKey));
memset(mSalt, 0, sizeof(mSalt));
memset(&mMasterKeyEncryption, 0, sizeof(mMasterKeyEncryption));
memset(&mMasterKeyDecryption, 0, sizeof(mMasterKeyDecryption));
}
ResponseCode initialize(const android::String8& pw, Entropy* entropy) {
if (!generateMasterKey(entropy)) {
return SYSTEM_ERROR;
}
ResponseCode response = writeMasterKey(pw, entropy);
if (response != NO_ERROR) {
return response;
}
setupMasterKeys();
return ::NO_ERROR;
}
ResponseCode writeMasterKey(const android::String8& pw, Entropy* entropy) {
uint8_t passwordKey[MASTER_KEY_SIZE_BYTES];
generateKeyFromPassword(passwordKey, MASTER_KEY_SIZE_BYTES, pw, mSalt);
AES_KEY passwordAesKey;
AES_set_encrypt_key(passwordKey, MASTER_KEY_SIZE_BITS, &passwordAesKey);
Blob masterKeyBlob(mMasterKey, sizeof(mMasterKey), mSalt, sizeof(mSalt), TYPE_MASTER_KEY);
return masterKeyBlob.writeBlob(mMasterKeyFile, &passwordAesKey, STATE_NO_ERROR, entropy);
}
ResponseCode readMasterKey(const android::String8& pw, Entropy* entropy) {
int in = TEMP_FAILURE_RETRY(open(mMasterKeyFile, O_RDONLY));
if (in < 0) {
return SYSTEM_ERROR;
}
// we read the raw blob to just to get the salt to generate
// the AES key, then we create the Blob to use with decryptBlob
blob rawBlob;
size_t length = readFully(in, (uint8_t*) &rawBlob, sizeof(rawBlob));
if (close(in) != 0) {
return SYSTEM_ERROR;
}
// find salt at EOF if present, otherwise we have an old file
uint8_t* salt;
if (length > SALT_SIZE && rawBlob.info == SALT_SIZE) {
salt = (uint8_t*) &rawBlob + length - SALT_SIZE;
} else {
salt = NULL;
}
uint8_t passwordKey[MASTER_KEY_SIZE_BYTES];
generateKeyFromPassword(passwordKey, MASTER_KEY_SIZE_BYTES, pw, salt);
AES_KEY passwordAesKey;
AES_set_decrypt_key(passwordKey, MASTER_KEY_SIZE_BITS, &passwordAesKey);
Blob masterKeyBlob(rawBlob);
ResponseCode response = masterKeyBlob.readBlob(mMasterKeyFile, &passwordAesKey,
STATE_NO_ERROR);
if (response == SYSTEM_ERROR) {
return response;
}
if (response == NO_ERROR && masterKeyBlob.getLength() == MASTER_KEY_SIZE_BYTES) {
// if salt was missing, generate one and write a new master key file with the salt.
if (salt == NULL) {
if (!generateSalt(entropy)) {
return SYSTEM_ERROR;
}
response = writeMasterKey(pw, entropy);
}
if (response == NO_ERROR) {
memcpy(mMasterKey, masterKeyBlob.getValue(), MASTER_KEY_SIZE_BYTES);
setupMasterKeys();
}
return response;
}
if (mRetry <= 0) {
reset();
return UNINITIALIZED;
}
--mRetry;
switch (mRetry) {
case 0: return WRONG_PASSWORD_0;
case 1: return WRONG_PASSWORD_1;
case 2: return WRONG_PASSWORD_2;
case 3: return WRONG_PASSWORD_3;
default: return WRONG_PASSWORD_3;
}
}
AES_KEY* getEncryptionKey() {
return &mMasterKeyEncryption;
}
AES_KEY* getDecryptionKey() {
return &mMasterKeyDecryption;
}
bool reset() {
DIR* dir = opendir(getUserDirName());
if (!dir) {
ALOGW("couldn't open user directory: %s", strerror(errno));
return false;
}
struct dirent* file;
while ((file = readdir(dir)) != NULL) {
// We only care about files.
if (file->d_type != DT_REG) {
continue;
}
// Skip anything that starts with a "."
if (file->d_name[0] == '.') {
continue;
}
// Find the current file's UID.
char* end;
unsigned long thisUid = strtoul(file->d_name, &end, 10);
if (end[0] != '_' || end[1] == 0) {
continue;
}
// Skip if this is not our user.
if (get_user_id(thisUid) != mUserId) {
continue;
}
unlinkat(dirfd(dir), file->d_name, 0);
}
closedir(dir);
return true;
}
private:
static const int MASTER_KEY_SIZE_BYTES = 16;
static const int MASTER_KEY_SIZE_BITS = MASTER_KEY_SIZE_BYTES * 8;
static const int MAX_RETRY = 4;
static const size_t SALT_SIZE = 16;
void generateKeyFromPassword(uint8_t* key, ssize_t keySize, const android::String8& pw,
uint8_t* salt) {
size_t saltSize;
if (salt != NULL) {
saltSize = SALT_SIZE;
} else {
// pre-gingerbread used this hardwired salt, readMasterKey will rewrite these when found
salt = (uint8_t*) "keystore";
// sizeof = 9, not strlen = 8
saltSize = sizeof("keystore");
}
PKCS5_PBKDF2_HMAC_SHA1(reinterpret_cast<const char*>(pw.string()), pw.length(), salt,
saltSize, 8192, keySize, key);
}
bool generateSalt(Entropy* entropy) {
return entropy->generate_random_data(mSalt, sizeof(mSalt));
}
bool generateMasterKey(Entropy* entropy) {
if (!entropy->generate_random_data(mMasterKey, sizeof(mMasterKey))) {
return false;
}
if (!generateSalt(entropy)) {
return false;
}
return true;
}
void setupMasterKeys() {
AES_set_encrypt_key(mMasterKey, MASTER_KEY_SIZE_BITS, &mMasterKeyEncryption);
AES_set_decrypt_key(mMasterKey, MASTER_KEY_SIZE_BITS, &mMasterKeyDecryption);
setState(STATE_NO_ERROR);
}
uid_t mUserId;
char* mUserDir;
char* mMasterKeyFile;
State mState;
int8_t mRetry;
uint8_t mMasterKey[MASTER_KEY_SIZE_BYTES];
uint8_t mSalt[SALT_SIZE];
AES_KEY mMasterKeyEncryption;
AES_KEY mMasterKeyDecryption;
};
typedef struct {
uint32_t uid;
const uint8_t* filename;
} grant_t;
class KeyStore {
public:
KeyStore(Entropy* entropy, keymaster_device_t* device)
: mEntropy(entropy)
, mDevice(device)
{
memset(&mMetaData, '\0', sizeof(mMetaData));
}
~KeyStore() {
for (android::Vector<grant_t*>::iterator it(mGrants.begin());
it != mGrants.end(); it++) {
delete *it;
mGrants.erase(it);
}
for (android::Vector<UserState*>::iterator it(mMasterKeys.begin());
it != mMasterKeys.end(); it++) {
delete *it;
mMasterKeys.erase(it);
}
}
keymaster_device_t* getDevice() const {
return mDevice;
}
ResponseCode initialize() {
readMetaData();
if (upgradeKeystore()) {
writeMetaData();
}
return ::NO_ERROR;
}
State getState(uid_t uid) {
return getUserState(uid)->getState();
}
ResponseCode initializeUser(const android::String8& pw, uid_t uid) {
UserState* userState = getUserState(uid);
return userState->initialize(pw, mEntropy);
}
ResponseCode writeMasterKey(const android::String8& pw, uid_t uid) {
uid_t user_id = get_user_id(uid);
UserState* userState = getUserState(user_id);
return userState->writeMasterKey(pw, mEntropy);
}
ResponseCode readMasterKey(const android::String8& pw, uid_t uid) {
uid_t user_id = get_user_id(uid);
UserState* userState = getUserState(user_id);
return userState->readMasterKey(pw, mEntropy);
}
android::String8 getKeyName(const android::String8& keyName) {
char encoded[encode_key_length(keyName)];
encode_key(encoded, keyName);
return android::String8(encoded);
}
android::String8 getKeyNameForUid(const android::String8& keyName, uid_t uid) {
char encoded[encode_key_length(keyName)];
encode_key(encoded, keyName);
return android::String8::format("%u_%s", uid, encoded);
}
android::String8 getKeyNameForUidWithDir(const android::String8& keyName, uid_t uid) {
char encoded[encode_key_length(keyName)];
encode_key(encoded, keyName);
return android::String8::format("%s/%u_%s", getUserState(uid)->getUserDirName(), uid,
encoded);
}
bool reset(uid_t uid) {
UserState* userState = getUserState(uid);
userState->zeroizeMasterKeysInMemory();
userState->setState(STATE_UNINITIALIZED);
return userState->reset();
}
bool isEmpty(uid_t uid) const {
const UserState* userState = getUserState(uid);
if (userState == NULL) {
return true;
}
DIR* dir = opendir(userState->getUserDirName());
struct dirent* file;
if (!dir) {
return true;
}
bool result = true;
char filename[NAME_MAX];
int n = snprintf(filename, sizeof(filename), "%u_", uid);
while ((file = readdir(dir)) != NULL) {
// We only care about files.
if (file->d_type != DT_REG) {
continue;
}
// Skip anything that starts with a "."
if (file->d_name[0] == '.') {
continue;
}
if (!strncmp(file->d_name, filename, n)) {
result = false;
break;
}
}
closedir(dir);
return result;
}
void lock(uid_t uid) {
UserState* userState = getUserState(uid);
userState->zeroizeMasterKeysInMemory();
userState->setState(STATE_LOCKED);
}
ResponseCode get(const char* filename, Blob* keyBlob, const BlobType type, uid_t uid) {
UserState* userState = getUserState(uid);
ResponseCode rc = keyBlob->readBlob(filename, userState->getDecryptionKey(),
userState->getState());
if (rc != NO_ERROR) {
return rc;
}
const uint8_t version = keyBlob->getVersion();
if (version < CURRENT_BLOB_VERSION) {
/* If we upgrade the key, we need to write it to disk again. Then
* it must be read it again since the blob is encrypted each time
* it's written.
*/
if (upgradeBlob(filename, keyBlob, version, type, uid)) {
if ((rc = this->put(filename, keyBlob, uid)) != NO_ERROR
|| (rc = keyBlob->readBlob(filename, userState->getDecryptionKey(),
userState->getState())) != NO_ERROR) {
return rc;
}
}
}
if (type != TYPE_ANY && keyBlob->getType() != type) {
ALOGW("key found but type doesn't match: %d vs %d", keyBlob->getType(), type);
return KEY_NOT_FOUND;
}
return rc;
}
ResponseCode put(const char* filename, Blob* keyBlob, uid_t uid) {
UserState* userState = getUserState(uid);
return keyBlob->writeBlob(filename, userState->getEncryptionKey(), userState->getState(),
mEntropy);
}
void addGrant(const char* filename, uid_t granteeUid) {
const grant_t* existing = getGrant(filename, granteeUid);
if (existing == NULL) {
grant_t* grant = new grant_t;
grant->uid = granteeUid;
grant->filename = reinterpret_cast<const uint8_t*>(strdup(filename));
mGrants.add(grant);
}
}
bool removeGrant(const char* filename, uid_t granteeUid) {
for (android::Vector<grant_t*>::iterator it(mGrants.begin());
it != mGrants.end(); it++) {
grant_t* grant = *it;
if (grant->uid == granteeUid
&& !strcmp(reinterpret_cast<const char*>(grant->filename), filename)) {
mGrants.erase(it);
return true;
}
}
return false;
}
bool hasGrant(const char* filename, const uid_t uid) const {
return getGrant(filename, uid) != NULL;
}
ResponseCode importKey(const uint8_t* key, size_t keyLen, const char* filename, uid_t uid,
int32_t flags) {
uint8_t* data;
size_t dataLength;
int rc;
if (mDevice->import_keypair == NULL) {
ALOGE("Keymaster doesn't support import!");
return SYSTEM_ERROR;
}
rc = mDevice->import_keypair(mDevice, key, keyLen, &data, &dataLength);
if (rc) {
ALOGE("Error while importing keypair: %d", rc);
return SYSTEM_ERROR;
}
Blob keyBlob(data, dataLength, NULL, 0, TYPE_KEY_PAIR);
free(data);
keyBlob.setEncrypted(flags & KEYSTORE_FLAG_ENCRYPTED);
return put(filename, &keyBlob, uid);
}
bool isHardwareBacked() const {
return (mDevice->flags & KEYMASTER_SOFTWARE_ONLY) == 0;
}
ResponseCode getKeyForName(Blob* keyBlob, const android::String8& keyName, const uid_t uid,
const BlobType type) {
char filename[NAME_MAX];
encode_key_for_uid(filename, uid, keyName);
UserState* userState = getUserState(uid);
android::String8 filepath8;
filepath8 = android::String8::format("%s/%s", userState->getUserDirName(), filename);
if (filepath8.string() == NULL) {
ALOGW("can't create filepath for key %s", filename);
return SYSTEM_ERROR;
}
ResponseCode responseCode = get(filepath8.string(), keyBlob, type, uid);
if (responseCode == NO_ERROR) {
return responseCode;
}
// If this is one of the legacy UID->UID mappings, use it.
uid_t euid = get_keystore_euid(uid);
if (euid != uid) {
encode_key_for_uid(filename, euid, keyName);
filepath8 = android::String8::format("%s/%s", userState->getUserDirName(), filename);
responseCode = get(filepath8.string(), keyBlob, type, uid);
if (responseCode == NO_ERROR) {
return responseCode;
}
}
// They might be using a granted key.
encode_key(filename, keyName);
char* end;
strtoul(filename, &end, 10);
if (end[0] != '_' || end[1] == 0) {
return KEY_NOT_FOUND;
}
filepath8 = android::String8::format("%s/%s", userState->getUserDirName(), filename);
if (!hasGrant(filepath8.string(), uid)) {
return responseCode;
}
// It is a granted key. Try to load it.
return get(filepath8.string(), keyBlob, type, uid);
}
/**
* Returns any existing UserState or creates it if it doesn't exist.
*/
UserState* getUserState(uid_t uid) {
uid_t userId = get_user_id(uid);
for (android::Vector<UserState*>::iterator it(mMasterKeys.begin());
it != mMasterKeys.end(); it++) {
UserState* state = *it;
if (state->getUserId() == userId) {
return state;
}
}
UserState* userState = new UserState(userId);
if (!userState->initialize()) {
/* There's not much we can do if initialization fails. Trying to
* unlock the keystore for that user will fail as well, so any
* subsequent request for this user will just return SYSTEM_ERROR.
*/
ALOGE("User initialization failed for %u; subsuquent operations will fail", userId);
}
mMasterKeys.add(userState);
return userState;
}
/**
* Returns NULL if the UserState doesn't already exist.
*/
const UserState* getUserState(uid_t uid) const {
uid_t userId = get_user_id(uid);
for (android::Vector<UserState*>::const_iterator it(mMasterKeys.begin());
it != mMasterKeys.end(); it++) {
UserState* state = *it;
if (state->getUserId() == userId) {
return state;
}
}
return NULL;
}
private:
static const char* sOldMasterKey;
static const char* sMetaDataFile;
Entropy* mEntropy;
keymaster_device_t* mDevice;
android::Vector<UserState*> mMasterKeys;
android::Vector<grant_t*> mGrants;
typedef struct {
uint32_t version;
} keystore_metadata_t;
keystore_metadata_t mMetaData;
const grant_t* getGrant(const char* filename, uid_t uid) const {
for (android::Vector<grant_t*>::const_iterator it(mGrants.begin());
it != mGrants.end(); it++) {
grant_t* grant = *it;
if (grant->uid == uid
&& !strcmp(reinterpret_cast<const char*>(grant->filename), filename)) {
return grant;
}
}
return NULL;
}
/**
* Upgrade code. This will upgrade the key from the current version
* to whatever is newest.
*/
bool upgradeBlob(const char* filename, Blob* blob, const uint8_t oldVersion,
const BlobType type, uid_t uid) {
bool updated = false;
uint8_t version = oldVersion;
/* From V0 -> V1: All old types were unknown */
if (version == 0) {
ALOGV("upgrading to version 1 and setting type %d", type);
blob->setType(type);
if (type == TYPE_KEY_PAIR) {
importBlobAsKey(blob, filename, uid);
}
version = 1;
updated = true;
}
/* From V1 -> V2: All old keys were encrypted */
if (version == 1) {
ALOGV("upgrading to version 2");
blob->setEncrypted(true);
version = 2;
updated = true;
}
/*
* If we've updated, set the key blob to the right version
* and write it.
*/
if (updated) {
ALOGV("updated and writing file %s", filename);
blob->setVersion(version);
}
return updated;
}
/**
* Takes a blob that is an PEM-encoded RSA key as a byte array and
* converts it to a DER-encoded PKCS#8 for import into a keymaster.
* Then it overwrites the original blob with the new blob
* format that is returned from the keymaster.
*/
ResponseCode importBlobAsKey(Blob* blob, const char* filename, uid_t uid) {
// We won't even write to the blob directly with this BIO, so const_cast is okay.
Unique_BIO b(BIO_new_mem_buf(const_cast<uint8_t*>(blob->getValue()), blob->getLength()));
if (b.get() == NULL) {
ALOGE("Problem instantiating BIO");
return SYSTEM_ERROR;
}
Unique_EVP_PKEY pkey(PEM_read_bio_PrivateKey(b.get(), NULL, NULL, NULL));
if (pkey.get() == NULL) {
ALOGE("Couldn't read old PEM file");
return SYSTEM_ERROR;
}
Unique_PKCS8_PRIV_KEY_INFO pkcs8(EVP_PKEY2PKCS8(pkey.get()));
int len = i2d_PKCS8_PRIV_KEY_INFO(pkcs8.get(), NULL);
if (len < 0) {
ALOGE("Couldn't measure PKCS#8 length");
return SYSTEM_ERROR;
}
UniquePtr<unsigned char[]> pkcs8key(new unsigned char[len]);
uint8_t* tmp = pkcs8key.get();
if (i2d_PKCS8_PRIV_KEY_INFO(pkcs8.get(), &tmp) != len) {
ALOGE("Couldn't convert to PKCS#8");
return SYSTEM_ERROR;
}
ResponseCode rc = importKey(pkcs8key.get(), len, filename, uid,
blob->isEncrypted() ? KEYSTORE_FLAG_ENCRYPTED : KEYSTORE_FLAG_NONE);
if (rc != NO_ERROR) {
return rc;
}
return get(filename, blob, TYPE_KEY_PAIR, uid);
}
void readMetaData() {
int in = TEMP_FAILURE_RETRY(open(sMetaDataFile, O_RDONLY));
if (in < 0) {
return;
}
size_t fileLength = readFully(in, (uint8_t*) &mMetaData, sizeof(mMetaData));
if (fileLength != sizeof(mMetaData)) {
ALOGI("Metadata file is %zd bytes (%zd experted); upgrade?", fileLength,
sizeof(mMetaData));
}
close(in);
}
void writeMetaData() {
const char* tmpFileName = ".metadata.tmp";
int out = TEMP_FAILURE_RETRY(open(tmpFileName,
O_WRONLY | O_TRUNC | O_CREAT, S_IRUSR | S_IWUSR));
if (out < 0) {
ALOGE("couldn't write metadata file: %s", strerror(errno));
return;
}
size_t fileLength = writeFully(out, (uint8_t*) &mMetaData, sizeof(mMetaData));
if (fileLength != sizeof(mMetaData)) {
ALOGI("Could only write %zd bytes to metadata file (%zd expected)", fileLength,
sizeof(mMetaData));
}
close(out);
rename(tmpFileName, sMetaDataFile);
}
bool upgradeKeystore() {
bool upgraded = false;
if (mMetaData.version == 0) {
UserState* userState = getUserState(0);
// Initialize first so the directory is made.
userState->initialize();
// Migrate the old .masterkey file to user 0.
if (access(sOldMasterKey, R_OK) == 0) {
if (rename(sOldMasterKey, userState->getMasterKeyFileName()) < 0) {
ALOGE("couldn't migrate old masterkey: %s", strerror(errno));
return false;
}
}
// Initialize again in case we had a key.
userState->initialize();
// Try to migrate existing keys.
DIR* dir = opendir(".");
if (!dir) {
// Give up now; maybe we can upgrade later.
ALOGE("couldn't open keystore's directory; something is wrong");
return false;
}
struct dirent* file;
while ((file = readdir(dir)) != NULL) {
// We only care about files.
if (file->d_type != DT_REG) {
continue;
}
// Skip anything that starts with a "."
if (file->d_name[0] == '.') {
continue;
}
// Find the current file's user.
char* end;
unsigned long thisUid = strtoul(file->d_name, &end, 10);
if (end[0] != '_' || end[1] == 0) {
continue;
}
UserState* otherUser = getUserState(thisUid);
if (otherUser->getUserId() != 0) {
unlinkat(dirfd(dir), file->d_name, 0);
}
// Rename the file into user directory.
DIR* otherdir = opendir(otherUser->getUserDirName());
if (otherdir == NULL) {
ALOGW("couldn't open user directory for rename");
continue;
}
if (renameat(dirfd(dir), file->d_name, dirfd(otherdir), file->d_name) < 0) {
ALOGW("couldn't rename blob: %s: %s", file->d_name, strerror(errno));
}
closedir(otherdir);
}
closedir(dir);
mMetaData.version = 1;
upgraded = true;
}
return upgraded;
}
};
const char* KeyStore::sOldMasterKey = ".masterkey";
const char* KeyStore::sMetaDataFile = ".metadata";
namespace android {
class KeyStoreProxy : public BnKeystoreService, public IBinder::DeathRecipient {
public:
KeyStoreProxy(KeyStore* keyStore)
: mKeyStore(keyStore)
{
}
void binderDied(const wp<IBinder>&) {
ALOGE("binder death detected");
}
int32_t test() {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_TEST)) {
ALOGW("permission denied for %d: test", callingUid);
return ::PERMISSION_DENIED;
}
return mKeyStore->getState(callingUid);
}
int32_t get(const String16& name, uint8_t** item, size_t* itemLength) {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_GET)) {
ALOGW("permission denied for %d: get", callingUid);
return ::PERMISSION_DENIED;
}
String8 name8(name);
Blob keyBlob;
ResponseCode responseCode = mKeyStore->getKeyForName(&keyBlob, name8, callingUid,
TYPE_GENERIC);
if (responseCode != ::NO_ERROR) {
ALOGW("Could not read %s", name8.string());
*item = NULL;
*itemLength = 0;
return responseCode;
}
*item = (uint8_t*) malloc(keyBlob.getLength());
memcpy(*item, keyBlob.getValue(), keyBlob.getLength());
*itemLength = keyBlob.getLength();
return ::NO_ERROR;
}
int32_t insert(const String16& name, const uint8_t* item, size_t itemLength, int targetUid,
int32_t flags) {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_INSERT)) {
ALOGW("permission denied for %d: insert", callingUid);
return ::PERMISSION_DENIED;
}
State state = mKeyStore->getState(callingUid);
if ((flags & KEYSTORE_FLAG_ENCRYPTED) && !isKeystoreUnlocked(state)) {
ALOGD("calling get in state: %d", state);
return state;
}
if (targetUid == -1) {
targetUid = callingUid;
} else if (!is_granted_to(callingUid, targetUid)) {
return ::PERMISSION_DENIED;
}
String8 name8(name);
String8 filename(mKeyStore->getKeyNameForUidWithDir(name8, targetUid));
Blob keyBlob(item, itemLength, NULL, 0, ::TYPE_GENERIC);
return mKeyStore->put(filename.string(), &keyBlob, callingUid);
}
int32_t del(const String16& name, int targetUid) {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_DELETE)) {
ALOGW("permission denied for %d: del", callingUid);
return ::PERMISSION_DENIED;
}
if (targetUid == -1) {
targetUid = callingUid;
} else if (!is_granted_to(callingUid, targetUid)) {
return ::PERMISSION_DENIED;
}
String8 name8(name);
String8 filename(mKeyStore->getKeyNameForUidWithDir(name8, targetUid));
Blob keyBlob;
ResponseCode responseCode = mKeyStore->get(filename.string(), &keyBlob, TYPE_GENERIC,
callingUid);
if (responseCode != ::NO_ERROR) {
return responseCode;
}
return (unlink(filename) && errno != ENOENT) ? ::SYSTEM_ERROR : ::NO_ERROR;
}
int32_t exist(const String16& name, int targetUid) {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_EXIST)) {
ALOGW("permission denied for %d: exist", callingUid);
return ::PERMISSION_DENIED;
}
if (targetUid == -1) {
targetUid = callingUid;
} else if (!is_granted_to(callingUid, targetUid)) {
return ::PERMISSION_DENIED;
}
String8 name8(name);
String8 filename(mKeyStore->getKeyNameForUidWithDir(name8, targetUid));
if (access(filename.string(), R_OK) == -1) {
return (errno != ENOENT) ? ::SYSTEM_ERROR : ::KEY_NOT_FOUND;
}
return ::NO_ERROR;
}
int32_t saw(const String16& prefix, int targetUid, Vector<String16>* matches) {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_SAW)) {
ALOGW("permission denied for %d: saw", callingUid);
return ::PERMISSION_DENIED;
}
if (targetUid == -1) {
targetUid = callingUid;
} else if (!is_granted_to(callingUid, targetUid)) {
return ::PERMISSION_DENIED;
}
UserState* userState = mKeyStore->getUserState(targetUid);
DIR* dir = opendir(userState->getUserDirName());
if (!dir) {
ALOGW("can't open directory for user: %s", strerror(errno));
return ::SYSTEM_ERROR;
}
const String8 prefix8(prefix);
String8 filename(mKeyStore->getKeyNameForUid(prefix8, targetUid));
size_t n = filename.length();
struct dirent* file;
while ((file = readdir(dir)) != NULL) {
// We only care about files.
if (file->d_type != DT_REG) {
continue;
}
// Skip anything that starts with a "."
if (file->d_name[0] == '.') {
continue;
}
if (!strncmp(filename.string(), file->d_name, n)) {
const char* p = &file->d_name[n];
size_t plen = strlen(p);
size_t extra = decode_key_length(p, plen);
char *match = (char*) malloc(extra + 1);
if (match != NULL) {
decode_key(match, p, plen);
matches->push(String16(match, extra));
free(match);
} else {
ALOGW("could not allocate match of size %zd", extra);
}
}
}
closedir(dir);
return ::NO_ERROR;
}
int32_t reset() {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_RESET)) {
ALOGW("permission denied for %d: reset", callingUid);
return ::PERMISSION_DENIED;
}
ResponseCode rc = mKeyStore->reset(callingUid) ? ::NO_ERROR : ::SYSTEM_ERROR;
const keymaster_device_t* device = mKeyStore->getDevice();
if (device == NULL) {
ALOGE("No keymaster device!");
return ::SYSTEM_ERROR;
}
if (device->delete_all == NULL) {
ALOGV("keymaster device doesn't implement delete_all");
return rc;
}
if (device->delete_all(device)) {
ALOGE("Problem calling keymaster's delete_all");
return ::SYSTEM_ERROR;
}
return rc;
}
/*
* Here is the history. To improve the security, the parameters to generate the
* master key has been changed. To make a seamless transition, we update the
* file using the same password when the user unlock it for the first time. If
* any thing goes wrong during the transition, the new file will not overwrite
* the old one. This avoids permanent damages of the existing data.
*/
int32_t password(const String16& password) {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_PASSWORD)) {
ALOGW("permission denied for %d: password", callingUid);
return ::PERMISSION_DENIED;
}
const String8 password8(password);
switch (mKeyStore->getState(callingUid)) {
case ::STATE_UNINITIALIZED: {
// generate master key, encrypt with password, write to file, initialize mMasterKey*.
return mKeyStore->initializeUser(password8, callingUid);
}
case ::STATE_NO_ERROR: {
// rewrite master key with new password.
return mKeyStore->writeMasterKey(password8, callingUid);
}
case ::STATE_LOCKED: {
// read master key, decrypt with password, initialize mMasterKey*.
return mKeyStore->readMasterKey(password8, callingUid);
}
}
return ::SYSTEM_ERROR;
}
int32_t lock() {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_LOCK)) {
ALOGW("permission denied for %d: lock", callingUid);
return ::PERMISSION_DENIED;
}
State state = mKeyStore->getState(callingUid);
if (state != ::STATE_NO_ERROR) {
ALOGD("calling lock in state: %d", state);
return state;
}
mKeyStore->lock(callingUid);
return ::NO_ERROR;
}
int32_t unlock(const String16& pw) {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_UNLOCK)) {
ALOGW("permission denied for %d: unlock", callingUid);
return ::PERMISSION_DENIED;
}
State state = mKeyStore->getState(callingUid);
if (state != ::STATE_LOCKED) {
ALOGD("calling unlock when not locked");
return state;
}
const String8 password8(pw);
return password(pw);
}
int32_t zero() {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_ZERO)) {
ALOGW("permission denied for %d: zero", callingUid);
return -1;
}
return mKeyStore->isEmpty(callingUid) ? ::KEY_NOT_FOUND : ::NO_ERROR;
}
int32_t generate(const String16& name, int targetUid, int32_t flags) {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_INSERT)) {
ALOGW("permission denied for %d: generate", callingUid);
return ::PERMISSION_DENIED;
}
if (targetUid == -1) {
targetUid = callingUid;
} else if (!is_granted_to(callingUid, targetUid)) {
return ::PERMISSION_DENIED;
}
State state = mKeyStore->getState(callingUid);
if ((flags & KEYSTORE_FLAG_ENCRYPTED) && !isKeystoreUnlocked(state)) {
ALOGW("calling generate in state: %d", state);
return state;
}
uint8_t* data;
size_t dataLength;
int rc;
const keymaster_device_t* device = mKeyStore->getDevice();
if (device == NULL) {
return ::SYSTEM_ERROR;
}
if (device->generate_keypair == NULL) {
return ::SYSTEM_ERROR;
}
keymaster_rsa_keygen_params_t rsa_params;
rsa_params.modulus_size = 2048;
rsa_params.public_exponent = 0x10001;
rc = device->generate_keypair(device, TYPE_RSA, &rsa_params, &data, &dataLength);
if (rc) {
return ::SYSTEM_ERROR;
}
String8 name8(name);
String8 filename(mKeyStore->getKeyNameForUidWithDir(name8, callingUid));
Blob keyBlob(data, dataLength, NULL, 0, TYPE_KEY_PAIR);
free(data);
return mKeyStore->put(filename.string(), &keyBlob, callingUid);
}
int32_t import(const String16& name, const uint8_t* data, size_t length, int targetUid,
int32_t flags) {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_INSERT)) {
ALOGW("permission denied for %d: import", callingUid);
return ::PERMISSION_DENIED;
}
if (targetUid == -1) {
targetUid = callingUid;
} else if (!is_granted_to(callingUid, targetUid)) {
return ::PERMISSION_DENIED;
}
State state = mKeyStore->getState(callingUid);
if ((flags & KEYSTORE_FLAG_ENCRYPTED) && !isKeystoreUnlocked(state)) {
ALOGD("calling import in state: %d", state);
return state;
}
String8 name8(name);
String8 filename(mKeyStore->getKeyNameForUidWithDir(name8, targetUid));
return mKeyStore->importKey(data, length, filename.string(), callingUid, flags);
}
int32_t sign(const String16& name, const uint8_t* data, size_t length, uint8_t** out,
size_t* outLength) {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_SIGN)) {
ALOGW("permission denied for %d: saw", callingUid);
return ::PERMISSION_DENIED;
}
Blob keyBlob;
String8 name8(name);
ALOGV("sign %s from uid %d", name8.string(), callingUid);
int rc;
ResponseCode responseCode = mKeyStore->getKeyForName(&keyBlob, name8, callingUid,
::TYPE_KEY_PAIR);
if (responseCode != ::NO_ERROR) {
return responseCode;
}
const keymaster_device_t* device = mKeyStore->getDevice();
if (device == NULL) {
ALOGE("no keymaster device; cannot sign");
return ::SYSTEM_ERROR;
}
if (device->sign_data == NULL) {
ALOGE("device doesn't implement signing");
return ::SYSTEM_ERROR;
}
keymaster_rsa_sign_params_t params;
params.digest_type = DIGEST_NONE;
params.padding_type = PADDING_NONE;
rc = device->sign_data(device, &params, keyBlob.getValue(), keyBlob.getLength(),
data, length, out, outLength);
if (rc) {
ALOGW("device couldn't sign data");
return ::SYSTEM_ERROR;
}
return ::NO_ERROR;
}
int32_t verify(const String16& name, const uint8_t* data, size_t dataLength,
const uint8_t* signature, size_t signatureLength) {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_VERIFY)) {
ALOGW("permission denied for %d: verify", callingUid);
return ::PERMISSION_DENIED;
}
State state = mKeyStore->getState(callingUid);
if (!isKeystoreUnlocked(state)) {
ALOGD("calling verify in state: %d", state);
return state;
}
Blob keyBlob;
String8 name8(name);
int rc;
ResponseCode responseCode = mKeyStore->getKeyForName(&keyBlob, name8, callingUid,
TYPE_KEY_PAIR);
if (responseCode != ::NO_ERROR) {
return responseCode;
}
const keymaster_device_t* device = mKeyStore->getDevice();
if (device == NULL) {
return ::SYSTEM_ERROR;
}
if (device->verify_data == NULL) {
return ::SYSTEM_ERROR;
}
keymaster_rsa_sign_params_t params;
params.digest_type = DIGEST_NONE;
params.padding_type = PADDING_NONE;
rc = device->verify_data(device, &params, keyBlob.getValue(), keyBlob.getLength(),
data, dataLength, signature, signatureLength);
if (rc) {
return ::SYSTEM_ERROR;
} else {
return ::NO_ERROR;
}
}
/*
* TODO: The abstraction between things stored in hardware and regular blobs
* of data stored on the filesystem should be moved down to keystore itself.
* Unfortunately the Java code that calls this has naming conventions that it
* knows about. Ideally keystore shouldn't be used to store random blobs of
* data.
*
* Until that happens, it's necessary to have a separate "get_pubkey" and
* "del_key" since the Java code doesn't really communicate what it's
* intentions are.
*/
int32_t get_pubkey(const String16& name, uint8_t** pubkey, size_t* pubkeyLength) {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_GET)) {
ALOGW("permission denied for %d: get_pubkey", callingUid);
return ::PERMISSION_DENIED;
}
Blob keyBlob;
String8 name8(name);
ALOGV("get_pubkey '%s' from uid %d", name8.string(), callingUid);
ResponseCode responseCode = mKeyStore->getKeyForName(&keyBlob, name8, callingUid,
TYPE_KEY_PAIR);
if (responseCode != ::NO_ERROR) {
return responseCode;
}
const keymaster_device_t* device = mKeyStore->getDevice();
if (device == NULL) {
return ::SYSTEM_ERROR;
}
if (device->get_keypair_public == NULL) {
ALOGE("device has no get_keypair_public implementation!");
return ::SYSTEM_ERROR;
}
int rc = device->get_keypair_public(device, keyBlob.getValue(), keyBlob.getLength(), pubkey,
pubkeyLength);
if (rc) {
return ::SYSTEM_ERROR;
}
return ::NO_ERROR;
}
int32_t del_key(const String16& name, int targetUid) {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_DELETE)) {
ALOGW("permission denied for %d: del_key", callingUid);
return ::PERMISSION_DENIED;
}
if (targetUid == -1) {
targetUid = callingUid;
} else if (!is_granted_to(callingUid, targetUid)) {
return ::PERMISSION_DENIED;
}
String8 name8(name);
String8 filename(mKeyStore->getKeyNameForUidWithDir(name8, callingUid));
Blob keyBlob;
ResponseCode responseCode = mKeyStore->get(filename.string(), &keyBlob, ::TYPE_KEY_PAIR,
callingUid);
if (responseCode != ::NO_ERROR) {
return responseCode;
}
ResponseCode rc = ::NO_ERROR;
const keymaster_device_t* device = mKeyStore->getDevice();
if (device == NULL) {
rc = ::SYSTEM_ERROR;
} else {
// A device doesn't have to implement delete_keypair.
if (device->delete_keypair != NULL) {
if (device->delete_keypair(device, keyBlob.getValue(), keyBlob.getLength())) {
rc = ::SYSTEM_ERROR;
}
}
}
if (rc != ::NO_ERROR) {
return rc;
}
return (unlink(filename) && errno != ENOENT) ? ::SYSTEM_ERROR : ::NO_ERROR;
}
int32_t grant(const String16& name, int32_t granteeUid) {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_GRANT)) {
ALOGW("permission denied for %d: grant", callingUid);
return ::PERMISSION_DENIED;
}
State state = mKeyStore->getState(callingUid);
if (!isKeystoreUnlocked(state)) {
ALOGD("calling grant in state: %d", state);
return state;
}
String8 name8(name);
String8 filename(mKeyStore->getKeyNameForUidWithDir(name8, callingUid));
if (access(filename.string(), R_OK) == -1) {
return (errno != ENOENT) ? ::SYSTEM_ERROR : ::KEY_NOT_FOUND;
}
mKeyStore->addGrant(filename.string(), granteeUid);
return ::NO_ERROR;
}
int32_t ungrant(const String16& name, int32_t granteeUid) {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_GRANT)) {
ALOGW("permission denied for %d: ungrant", callingUid);
return ::PERMISSION_DENIED;
}
State state = mKeyStore->getState(callingUid);
if (!isKeystoreUnlocked(state)) {
ALOGD("calling ungrant in state: %d", state);
return state;
}
String8 name8(name);
String8 filename(mKeyStore->getKeyNameForUidWithDir(name8, callingUid));
if (access(filename.string(), R_OK) == -1) {
return (errno != ENOENT) ? ::SYSTEM_ERROR : ::KEY_NOT_FOUND;
}
return mKeyStore->removeGrant(filename.string(), granteeUid) ? ::NO_ERROR : ::KEY_NOT_FOUND;
}
int64_t getmtime(const String16& name) {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_GET)) {
ALOGW("permission denied for %d: getmtime", callingUid);
return -1L;
}
String8 name8(name);
String8 filename(mKeyStore->getKeyNameForUidWithDir(name8, callingUid));
if (access(filename.string(), R_OK) == -1) {
ALOGW("could not access %s for getmtime", filename.string());
return -1L;
}
int fd = TEMP_FAILURE_RETRY(open(filename.string(), O_NOFOLLOW, O_RDONLY));
if (fd < 0) {
ALOGW("could not open %s for getmtime", filename.string());
return -1L;
}
struct stat s;
int ret = fstat(fd, &s);
close(fd);
if (ret == -1) {
ALOGW("could not stat %s for getmtime", filename.string());
return -1L;
}
return static_cast<int64_t>(s.st_mtime);
}
int32_t duplicate(const String16& srcKey, int32_t srcUid, const String16& destKey,
int32_t destUid) {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_DUPLICATE)) {
ALOGW("permission denied for %d: duplicate", callingUid);
return -1L;
}
State state = mKeyStore->getState(callingUid);
if (!isKeystoreUnlocked(state)) {
ALOGD("calling duplicate in state: %d", state);
return state;
}
if (srcUid == -1 || static_cast<uid_t>(srcUid) == callingUid) {
srcUid = callingUid;
} else if (!is_granted_to(callingUid, srcUid)) {
ALOGD("migrate not granted from source: %d -> %d", callingUid, srcUid);
return ::PERMISSION_DENIED;
}
if (destUid == -1) {
destUid = callingUid;
}
if (srcUid != destUid) {
if (static_cast<uid_t>(srcUid) != callingUid) {
ALOGD("can only duplicate from caller to other or to same uid: "
"calling=%d, srcUid=%d, destUid=%d", callingUid, srcUid, destUid);
return ::PERMISSION_DENIED;
}
if (!is_granted_to(callingUid, destUid)) {
ALOGD("duplicate not granted to dest: %d -> %d", callingUid, destUid);
return ::PERMISSION_DENIED;
}
}
String8 source8(srcKey);
String8 sourceFile(mKeyStore->getKeyNameForUidWithDir(source8, srcUid));
String8 target8(destKey);
String8 targetFile(mKeyStore->getKeyNameForUidWithDir(target8, srcUid));
if (access(targetFile.string(), W_OK) != -1 || errno != ENOENT) {
ALOGD("destination already exists: %s", targetFile.string());
return ::SYSTEM_ERROR;
}
Blob keyBlob;
ResponseCode responseCode = mKeyStore->get(sourceFile.string(), &keyBlob, TYPE_ANY,
callingUid);
if (responseCode != ::NO_ERROR) {
return responseCode;
}
return mKeyStore->put(targetFile.string(), &keyBlob, callingUid);
}
int32_t is_hardware_backed() {
return mKeyStore->isHardwareBacked() ? 1 : 0;
}
int32_t clear_uid(int64_t targetUid) {
uid_t callingUid = IPCThreadState::self()->getCallingUid();
if (!has_permission(callingUid, P_CLEAR_UID)) {
ALOGW("permission denied for %d: clear_uid", callingUid);
return ::PERMISSION_DENIED;
}
State state = mKeyStore->getState(callingUid);
if (!isKeystoreUnlocked(state)) {
ALOGD("calling clear_uid in state: %d", state);
return state;
}
const keymaster_device_t* device = mKeyStore->getDevice();
if (device == NULL) {
ALOGW("can't get keymaster device");
return ::SYSTEM_ERROR;
}
UserState* userState = mKeyStore->getUserState(callingUid);
DIR* dir = opendir(userState->getUserDirName());
if (!dir) {
ALOGW("can't open user directory: %s", strerror(errno));
return ::SYSTEM_ERROR;
}
char prefix[NAME_MAX];
int n = snprintf(prefix, NAME_MAX, "%u_", static_cast<uid_t>(targetUid));
ResponseCode rc = ::NO_ERROR;
struct dirent* file;
while ((file = readdir(dir)) != NULL) {
// We only care about files.
if (file->d_type != DT_REG) {
continue;
}
// Skip anything that starts with a "."
if (file->d_name[0] == '.') {
continue;
}
if (strncmp(prefix, file->d_name, n)) {
continue;
}
String8 filename(String8::format("%s/%s", userState->getUserDirName(), file->d_name));
Blob keyBlob;
if (mKeyStore->get(filename.string(), &keyBlob, ::TYPE_ANY, callingUid)
!= ::NO_ERROR) {
ALOGW("couldn't open %s", filename.string());
continue;
}
if (keyBlob.getType() == ::TYPE_KEY_PAIR) {
// A device doesn't have to implement delete_keypair.
if (device->delete_keypair != NULL) {
if (device->delete_keypair(device, keyBlob.getValue(), keyBlob.getLength())) {
rc = ::SYSTEM_ERROR;
ALOGW("device couldn't remove %s", filename.string());
}
}
}
if (unlinkat(dirfd(dir), file->d_name, 0) && errno != ENOENT) {
rc = ::SYSTEM_ERROR;
ALOGW("couldn't unlink %s", filename.string());
}
}
closedir(dir);
return rc;
}
private:
inline bool isKeystoreUnlocked(State state) {
switch (state) {
case ::STATE_NO_ERROR:
return true;
case ::STATE_UNINITIALIZED:
case ::STATE_LOCKED:
return false;
}
return false;
}
::KeyStore* mKeyStore;
};
}; // namespace android
int main(int argc, char* argv[]) {
if (argc < 2) {
ALOGE("A directory must be specified!");
return 1;
}
if (chdir(argv[1]) == -1) {
ALOGE("chdir: %s: %s", argv[1], strerror(errno));
return 1;
}
Entropy entropy;
if (!entropy.open()) {
return 1;
}
keymaster_device_t* dev;
if (keymaster_device_initialize(&dev)) {
ALOGE("keystore keymaster could not be initialized; exiting");
return 1;
}
KeyStore keyStore(&entropy, dev);
keyStore.initialize();
android::sp<android::IServiceManager> sm = android::defaultServiceManager();
android::sp<android::KeyStoreProxy> proxy = new android::KeyStoreProxy(&keyStore);
android::status_t ret = sm->addService(android::String16("android.security.keystore"), proxy);
if (ret != android::OK) {
ALOGE("Couldn't register binder service!");
return -1;
}
/*
* We're the only thread in existence, so we're just going to process
* Binder transaction as a single-threaded program.
*/
android::IPCThreadState::self()->joinThreadPool();
keymaster_device_release(dev);
return 1;
}