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android_system_vold
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Add keymaster1 support to vold.

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Bug: 21607106
Change-Id: I498141b90888d4f0652912413b04519f61886935
gugelfrei
Shawn Willden 9 years ago
parent b1ef4665e8
commit da6e899f4e
1 changed files with 193 additions and 52 deletions
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245
cryptfs.c
Unescape View File

@ -61,6 +61,7 @@
#include "Process.h"
#include <hardware/keymaster0.h>
#include <hardware/keymaster1.h>
#define UNUSED __attribute__((unused))
@ -88,6 +89,8 @@
#define RSA_KEY_SIZE 2048
#define RSA_KEY_SIZE_BYTES (RSA_KEY_SIZE / 8)
#define RSA_EXPONENT 0x10001
#define KEYMASTER_CRYPTFS_RATE_LIMIT 1 // Maximum one try per second
#define KEYMASTER_CRYPTFS_APP_ID "vold cryptfs"
#define RETRY_MOUNT_ATTEMPTS 10
#define RETRY_MOUNT_DELAY_SECONDS 1
@ -99,7 +102,8 @@ static char *saved_mount_point;
static int master_key_saved = 0;
static struct crypt_persist_data *persist_data = NULL;
static int keymaster_init(keymaster0_device_t **keymaster_dev)
static int keymaster_init(keymaster0_device_t **keymaster0_dev,
keymaster1_device_t **keymaster1_dev)
{
int rc;
@ -107,50 +111,74 @@ static int keymaster_init(keymaster0_device_t **keymaster_dev)
rc = hw_get_module_by_class(KEYSTORE_HARDWARE_MODULE_ID, NULL, &mod);
if (rc) {
ALOGE("could not find any keystore module");
goto out;
goto err;
}
SLOGI("keymaster module name is %s", mod->name);
SLOGI("keymaster version is %d", mod->module_api_version);
*keymaster0_dev = NULL;
*keymaster1_dev = NULL;
if (mod->module_api_version == KEYMASTER_MODULE_API_VERSION_1_0) {
SLOGI("Found keymaster1 module, using keymaster1 API.");
rc = keymaster1_open(mod, keymaster1_dev);
} else {
SLOGI("Found keymaster0 module, using keymaster0 API.");
rc = keymaster0_open(mod, keymaster0_dev);
}
rc = keymaster0_open(mod, keymaster_dev);
if (rc) {
ALOGE("could not open keymaster device in %s (%s)",
KEYSTORE_HARDWARE_MODULE_ID, strerror(-rc));
goto out;
KEYSTORE_HARDWARE_MODULE_ID, strerror(-rc));
goto err;
}
return 0;
out:
*keymaster_dev = NULL;
err:
*keymaster0_dev = NULL;
*keymaster1_dev = NULL;
return rc;
}
/* Should we use keymaster? */
static int keymaster_check_compatibility()
{
keymaster0_device_t *keymaster_dev = 0;
keymaster0_device_t *keymaster0_dev = 0;
keymaster1_device_t *keymaster1_dev = 0;
int rc = 0;
if (keymaster_init(&keymaster_dev)) {
if (keymaster_init(&keymaster0_dev, &keymaster1_dev)) {
SLOGE("Failed to init keymaster");
rc = -1;
goto out;
}
SLOGI("keymaster version is %d", keymaster_dev->common.module->module_api_version);
if (keymaster1_dev) {
rc = 1;
goto out;
}
if (keymaster_dev->common.module->module_api_version
// TODO(swillden): Check to see if there's any reason to require v0.3. I think v0.1 and v0.2
// should work.
if (keymaster0_dev->common.module->module_api_version
< KEYMASTER_MODULE_API_VERSION_0_3) {
rc = 0;
goto out;
}
if (!(keymaster_dev->flags & KEYMASTER_SOFTWARE_ONLY) &&
(keymaster_dev->flags & KEYMASTER_BLOBS_ARE_STANDALONE)) {
if (!(keymaster0_dev->flags & KEYMASTER_SOFTWARE_ONLY) &&
(keymaster0_dev->flags & KEYMASTER_BLOBS_ARE_STANDALONE)) {
rc = 1;
}
out:
keymaster0_close(keymaster_dev);
if (keymaster1_dev) {
keymaster1_close(keymaster1_dev);
}
if (keymaster0_dev) {
keymaster0_close(keymaster0_dev);
}
return rc;
}
@ -158,24 +186,72 @@ out:
static int keymaster_create_key(struct crypt_mnt_ftr *ftr)
{
uint8_t* key = 0;
keymaster0_device_t *keymaster_dev = 0;
keymaster0_device_t *keymaster0_dev = 0;
keymaster1_device_t *keymaster1_dev = 0;
if (keymaster_init(&keymaster_dev)) {
if (keymaster_init(&keymaster0_dev, &keymaster1_dev)) {
SLOGE("Failed to init keymaster");
return -1;
}
int rc = 0;
size_t key_size = 0;
if (keymaster1_dev) {
keymaster_key_param_t params[] = {
/* Algorithm & size specifications. Stick with RSA for now. Switch to AES later. */
keymaster_param_enum(KM_TAG_ALGORITHM, KM_ALGORITHM_RSA),
keymaster_param_int(KM_TAG_KEY_SIZE, RSA_KEY_SIZE),
keymaster_param_long(KM_TAG_RSA_PUBLIC_EXPONENT, RSA_EXPONENT),
/* Padding & digest specifications. We'll use none/none, but add better options
* just in case we want to use them later. Actual selection is done at operation
* time, but restricted to options specified at keygen. */
keymaster_param_enum(KM_TAG_PADDING, KM_PAD_NONE),
keymaster_param_enum(KM_TAG_PADDING, KM_PAD_RSA_PKCS1_1_5_SIGN),
keymaster_param_enum(KM_TAG_DIGEST, KM_DIGEST_NONE),
keymaster_param_enum(KM_TAG_DIGEST, KM_DIGEST_SHA_2_256),
/* Require that the key be usable in standalone mode. File system isn't available. */
keymaster_param_enum(KM_TAG_BLOB_USAGE_REQUIREMENTS, KM_BLOB_STANDALONE),
/* No auth requirements, because cryptfs is not yet integrated with gatekeeper. */
keymaster_param_bool(KM_TAG_NO_AUTH_REQUIRED),
/* Set app ID to a value keystore will never use */
keymaster_param_blob(KM_TAG_APPLICATION_ID, (uint8_t*)KEYMASTER_CRYPTFS_APP_ID,
sizeof(KEYMASTER_CRYPTFS_APP_ID)),
/* Rate-limit key usage attempts, to rate-limit brute force */
keymaster_param_int(KM_TAG_MIN_SECONDS_BETWEEN_OPS, KEYMASTER_CRYPTFS_RATE_LIMIT),
};
keymaster_key_param_set_t param_set = { params, sizeof(params)/sizeof(*params) };
keymaster_key_blob_t key_blob;
keymaster_error_t error = keymaster1_dev->generate_key(keymaster1_dev, &param_set,
&key_blob,
NULL /* characteristics */);
if (error != KM_ERROR_OK) {
SLOGE("Failed to generate keymaster1 key, error %d", error);
rc = -1;
goto out;
}
keymaster_rsa_keygen_params_t params;
memset(&params, '\0', sizeof(params));
params.public_exponent = RSA_EXPONENT;
params.modulus_size = RSA_KEY_SIZE;
key = (uint8_t*)key_blob.key_material;
key_size = key_blob.key_material_size;
}
else if (keymaster0_dev) {
keymaster_rsa_keygen_params_t params;
memset(&params, '\0', sizeof(params));
params.public_exponent = RSA_EXPONENT;
params.modulus_size = RSA_KEY_SIZE;
size_t key_size;
if (keymaster_dev->generate_keypair(keymaster_dev, TYPE_RSA, &params,
&key, &key_size)) {
SLOGE("Failed to generate keypair");
if (keymaster0_dev->generate_keypair(keymaster0_dev, TYPE_RSA, &params,
&key, &key_size)) {
SLOGE("Failed to generate keypair");
rc = -1;
goto out;
}
} else {
SLOGE("Cryptfs bug: keymaster_init succeeded but didn't initialize a device");
rc = -1;
goto out;
}
@ -190,7 +266,10 @@ static int keymaster_create_key(struct crypt_mnt_ftr *ftr)
ftr->keymaster_blob_size = key_size;
out:
keymaster0_close(keymaster_dev);
if (keymaster0_dev)
keymaster0_close(keymaster0_dev);
if (keymaster1_dev)
keymaster1_close(keymaster1_dev);
free(key);
return rc;
}
@ -203,20 +282,14 @@ static int keymaster_sign_object(struct crypt_mnt_ftr *ftr,
size_t *signature_size)
{
int rc = 0;
keymaster0_device_t *keymaster_dev = 0;
if (keymaster_init(&keymaster_dev)) {
keymaster0_device_t *keymaster0_dev = 0;
keymaster1_device_t *keymaster1_dev = 0;
if (keymaster_init(&keymaster0_dev, &keymaster1_dev)) {
SLOGE("Failed to init keymaster");
return -1;
rc = -1;
goto out;
}
/* We currently set the digest type to DIGEST_NONE because it's the
* only supported value for keymaster. A similar issue exists with
* PADDING_NONE. Long term both of these should likely change.
*/
keymaster_rsa_sign_params_t params;
params.digest_type = DIGEST_NONE;
params.padding_type = PADDING_NONE;
unsigned char to_sign[RSA_KEY_SIZE_BYTES];
size_t to_sign_size = sizeof(to_sign);
memset(to_sign, 0, RSA_KEY_SIZE_BYTES);
@ -241,30 +314,98 @@ static int keymaster_sign_object(struct crypt_mnt_ftr *ftr,
// is zero. We could have zero-padded to the left instead, but
// this approach is slightly more robust against changes in
// object size. However, it's still broken (but not unusably
// so) because we really should be using a proper RSA padding
// function, such as OAEP.
//
// TODO(paullawrence): When keymaster 0.4 is available, change
// this to use the padding options it provides.
// so) because we really should be using a proper deterministic
// RSA padding function, such as PKCS1.
memcpy(to_sign + 1, object, min(RSA_KEY_SIZE_BYTES - 1, object_size));
SLOGI("Signing safely-padded object");
break;
default:
SLOGE("Unknown KDF type %d", ftr->kdf_type);
return -1;
rc = -1;
goto out;
}
rc = keymaster_dev->sign_data(keymaster_dev,
&params,
ftr->keymaster_blob,
ftr->keymaster_blob_size,
to_sign,
to_sign_size,
signature,
signature_size);
if (keymaster0_dev) {
keymaster_rsa_sign_params_t params;
params.digest_type = DIGEST_NONE;
params.padding_type = PADDING_NONE;
keymaster0_close(keymaster_dev);
return rc;
rc = keymaster0_dev->sign_data(keymaster0_dev,
&params,
ftr->keymaster_blob,
ftr->keymaster_blob_size,
to_sign,
to_sign_size,
signature,
signature_size);
goto out;
} else if (keymaster1_dev) {
keymaster_key_blob_t key = { ftr->keymaster_blob, ftr->keymaster_blob_size };
keymaster_key_param_t params[] = {
keymaster_param_enum(KM_TAG_PADDING, KM_PAD_NONE),
keymaster_param_enum(KM_TAG_DIGEST, KM_DIGEST_NONE),
};
keymaster_key_param_set_t param_set = { params, sizeof(params)/sizeof(*params) };
keymaster_operation_handle_t op_handle;
keymaster_error_t error = keymaster1_dev->begin(keymaster1_dev, KM_PURPOSE_SIGN, &key,
&param_set, NULL /* out_params */,
&op_handle);
if (error == KM_ERROR_VERIFICATION_FAILED) {
// Key usage has been rate-limited. Wait a bit and try again.
sleep(KEYMASTER_CRYPTFS_RATE_LIMIT);
error = keymaster1_dev->begin(keymaster1_dev, KM_PURPOSE_SIGN, &key,
&param_set, NULL /* out_params */,
&op_handle);
}
if (error != KM_ERROR_OK) {
SLOGE("Error starting keymaster signature transaction: %d", error);
rc = -1;
goto out;
}
keymaster_blob_t input = { to_sign, to_sign_size };
size_t input_consumed;
error = keymaster1_dev->update(keymaster1_dev, op_handle, NULL /* in_params */,
&input, &input_consumed, NULL /* out_params */,
NULL /* output */);
if (error != KM_ERROR_OK) {
SLOGE("Error sending data to keymaster signature transaction: %d", error);
rc = -1;
goto out;
}
if (input_consumed != to_sign_size) {
// This should never happen. If it does, it's a bug in the keymaster implementation.
SLOGE("Keymaster update() did not consume all data.");
keymaster1_dev->abort(keymaster1_dev, op_handle);
rc = -1;
goto out;
}
keymaster_blob_t tmp_sig;
error = keymaster1_dev->finish(keymaster1_dev, op_handle, NULL /* in_params */,
NULL /* verify signature */, NULL /* out_params */,
&tmp_sig);
if (error != KM_ERROR_OK) {
SLOGE("Error finishing keymaster signature transaction: %d", error);
rc = -1;
goto out;
}
*signature = (uint8_t*)tmp_sig.data;
*signature_size = tmp_sig.data_length;
} else {
SLOGE("Cryptfs bug: keymaster_init succeded but didn't initialize a device.");
rc = -1;
goto out;
}
out:
if (keymaster1_dev)
keymaster1_close(keymaster1_dev);
if (keymaster0_dev)
keymaster0_close(keymaster0_dev);
return rc;
}
/* Store password when userdata is successfully decrypted and mounted.

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