replicant-frameworks_native/cmds/keystore/keymgmt.c

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/*
** Copyright 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.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <ctype.h>
#include <fcntl.h>
#include <dirent.h>
#include <errno.h>
#include <openssl/aes.h>
#include <openssl/evp.h>
#include <cutils/log.h>
#include "common.h"
#include "keymgmt.h"
static int retry_count = 0;
static unsigned char iv[IV_LEN];
static KEYSTORE_STATE state = BOOTUP;
static AES_KEY encryptKey, decryptKey;
inline void unlock_keystore(unsigned char *master_key)
{
AES_set_encrypt_key(master_key, AES_KEY_LEN, &encryptKey);
AES_set_decrypt_key(master_key, AES_KEY_LEN, &decryptKey);
memset(master_key, 0, sizeof(master_key));
state = UNLOCKED;
}
inline void lock_keystore()
{
memset(&encryptKey, 0 , sizeof(AES_KEY));
memset(&decryptKey, 0 , sizeof(AES_KEY));
state = LOCKED;
}
inline void get_encrypt_key(char *passwd, AES_KEY *key)
{
unsigned char user_key[USER_KEY_LEN];
gen_key(passwd, user_key, USER_KEY_LEN);
AES_set_encrypt_key(user_key, AES_KEY_LEN, key);
}
inline void get_decrypt_key(char *passwd, AES_KEY *key)
{
unsigned char user_key[USER_KEY_LEN];
gen_key(passwd, user_key, USER_KEY_LEN);
AES_set_decrypt_key(user_key, AES_KEY_LEN, key);
}
static int gen_random_blob(unsigned char *key, int size)
{
int ret = 0;
int fd = open("/dev/urandom", O_RDONLY);
if (fd == -1) return -1;
if (read(fd, key, size) != size) ret = -1;
close(fd);
return ret;
}
static int encrypt_n_save(AES_KEY *enc_key, DATA_BLOB *blob,
const char *keyfile)
{
int size, fd, ret = -1;
unsigned char enc_blob[MAX_BLOB_LEN];
char tmpfile[KEYFILE_LEN];
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if ((keyfile == NULL) || (strlen(keyfile) >= (KEYFILE_LEN - 4))) {
LOGE("keyfile name is too long or null");
return -1;
}
strcpy(tmpfile, keyfile);
strcat(tmpfile, ".tmp");
// prepare the blob
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if (IV_LEN > USER_KEY_LEN) {
LOGE("iv length is too long.");
return -1;
}
memcpy(blob->iv, iv, IV_LEN);
blob->blob_size = get_blob_size(blob);
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if (blob->blob_size > MAX_BLOB_LEN) {
LOGE("blob data size is too large.");
return -1;
}
memcpy(enc_blob, blob->blob, blob->blob_size);
AES_cbc_encrypt((unsigned char *)enc_blob, (unsigned char *)blob->blob,
blob->blob_size, enc_key, iv, AES_ENCRYPT);
// write to keyfile
size = data_blob_size(blob);
if ((fd = open(tmpfile, O_CREAT|O_RDWR)) == -1) return -1;
if (write(fd, blob, size) == size) ret = 0;
close(fd);
if (!ret) {
unlink(keyfile);
rename(tmpfile, keyfile);
chmod(keyfile, 0440);
}
return ret;
}
static int load_n_decrypt(const char *keyname, const char *keyfile,
AES_KEY *key, DATA_BLOB *blob)
{
int fd, ret = -1;
if ((fd = open(keyfile, O_RDONLY)) == -1) return -1;
// get the encrypted blob and iv
if ((read(fd, blob->iv, sizeof(blob->iv)) != sizeof(blob->iv)) ||
(read(fd, &blob->blob_size, sizeof(uint32_t)) != sizeof(uint32_t)) ||
(blob->blob_size > MAX_BLOB_LEN)) {
goto err;
} else {
unsigned char enc_blob[MAX_BLOB_LEN];
if (read(fd, enc_blob, blob->blob_size) !=
(int) blob->blob_size) goto err;
// decrypt the blob
AES_cbc_encrypt((unsigned char *)enc_blob, (unsigned char*)blob->blob,
blob->blob_size, key, blob->iv, AES_DECRYPT);
if (strcmp(keyname, (char*)blob->keyname) == 0) ret = 0;
}
err:
close(fd);
return ret;
}
static int store_master_key(char *upasswd, unsigned char *master_key)
{
AES_KEY key;
DATA_BLOB blob;
// prepare the blob
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if (strlen(MASTER_KEY_TAG) >= USER_KEY_LEN) return -1;
strlcpy(blob.keyname, MASTER_KEY_TAG, USER_KEY_LEN);
blob.value_size = USER_KEY_LEN;
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if (USER_KEY_LEN > MAX_KEY_VALUE_LENGTH) {
LOGE("master_key length is too long.");
return -1;
}
memcpy((void*)blob.value, (const void*)master_key, USER_KEY_LEN);
// generate the encryption key
get_encrypt_key(upasswd, &key);
return encrypt_n_save(&key, &blob, MASTER_KEY);
}
static int get_master_key(char *upasswd, unsigned char *master_key)
{
AES_KEY key;
int size, ret = 0;
DATA_BLOB blob;
get_decrypt_key(upasswd, &key);
ret = load_n_decrypt(MASTER_KEY_TAG, MASTER_KEY, &key, &blob);
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if (blob.value_size > USER_KEY_LEN) {
LOGE("the blob's value size is too large");
return -1;
}
if (!ret) memcpy(master_key, blob.value, blob.value_size);
return ret;
}
static int create_master_key(char *upasswd)
{
int ret;
unsigned char mpasswd[AES_KEY_LEN];
unsigned char master_key[USER_KEY_LEN];
gen_random_blob(mpasswd, AES_KEY_LEN);
gen_key((char*)mpasswd, master_key, USER_KEY_LEN);
if ((ret = store_master_key(upasswd, master_key)) == 0) {
unlock_keystore(master_key);
}
memset(master_key, 0, USER_KEY_LEN);
memset(mpasswd, 0, AES_KEY_LEN);
return ret;
}
static int change_passwd(char *data)
{
unsigned char master_key[USER_KEY_LEN];
char *old_pass, *new_pass = NULL, *p, *delimiter=" ";
int ret, count = 0;
char *context = NULL;
old_pass = p = strtok_r(data, delimiter, &context);
while (p != NULL) {
count++;
new_pass = p;
p = strtok_r(NULL, delimiter, &context);
}
if (count != 2) return -1;
if (strlen(new_pass) < MIN_PASSWD_LENGTH) return -1;
if ((ret = get_master_key(old_pass, master_key)) == 0) {
ret = store_master_key(new_pass, master_key);
retry_count = 0;
} else {
ret = MAX_RETRY_COUNT - ++retry_count;
if (ret == 0) {
retry_count = 0;
LOGE("passwd:reach max retry count, reset the keystore now.");
reset_keystore();
return -1;
}
}
return ret;
}
int remove_key(const char *namespace, const char *keyname)
{
char keyfile[KEYFILE_LEN];
if (state != UNLOCKED) return -state;
sprintf(keyfile, KEYFILE_NAME, namespace, keyname);
return unlink(keyfile);
}
int put_key(const char *namespace, const char *keyname,
unsigned char *data, int size)
{
DATA_BLOB blob;
uint32_t real_size;
char keyfile[KEYFILE_LEN];
if (state != UNLOCKED) {
LOGE("Can not store key with current state %d\n", state);
return -state;
}
sprintf(keyfile, KEYFILE_NAME, namespace, keyname);
// flatten the args
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if (strlen(keyname) >= MAX_KEY_NAME_LENGTH) {
LOGE("keyname is too long.");
return -1;
}
strcpy(blob.keyname, keyname);
blob.value_size = size;
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if (size > MAX_KEY_VALUE_LENGTH) {
LOGE("the data size is too large.");
return -1;
}
memcpy(blob.value, data, size);
return encrypt_n_save(&encryptKey, &blob, keyfile);
}
int get_key(const char *namespace, const char *keyname,
unsigned char *data, int *size)
{
int ret;
DATA_BLOB blob;
uint32_t blob_size;
char keyfile[KEYFILE_LEN];
if (state != UNLOCKED) {
LOGE("Can not retrieve key value with current state %d\n", state);
return -state;
}
sprintf(keyfile, KEYFILE_NAME, namespace, keyname);
ret = load_n_decrypt(keyname, keyfile, &decryptKey, &blob);
if (!ret) {
if ((blob.value_size > MAX_KEY_VALUE_LENGTH)) {
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LOGE("blob value size is too large.");
ret = -1;
} else {
*size = blob.value_size;
memcpy(data, blob.value, *size);
}
}
return ret;
}
int list_keys(const char *namespace, char reply[BUFFER_MAX])
{
DIR *d;
struct dirent *de;
if (state != UNLOCKED) {
LOGE("Can not list key with current state %d\n", state);
return -1;
}
if (!namespace || ((d = opendir("."))) == NULL) {
LOGE("cannot open keystore dir or namespace is null\n");
return -1;
}
while ((de = readdir(d))) {
char *prefix, *name, *keyfile = de->d_name;
char *context = NULL;
if (de->d_type != DT_REG) continue;
if ((prefix = strtok_r(keyfile, NAME_DELIMITER, &context))
== NULL) continue;
if (strcmp(prefix, namespace)) continue;
if ((name = strtok_r(NULL, NAME_DELIMITER, &context)) == NULL) continue;
// append the key name into reply
if (reply[0] != 0) strlcat(reply, " ", BUFFER_MAX);
if (strlcat(reply, name, BUFFER_MAX) >= BUFFER_MAX) {
LOGE("too many files under keystore directory\n");
return -1;
}
}
closedir(d);
return 0;
}
int passwd(char *data)
{
if (state == UNINITIALIZED) {
if (strchr(data, ' ')) return -1;
if (strlen(data) < MIN_PASSWD_LENGTH) return -1;
return create_master_key(data);
}
return change_passwd(data);
}
int lock()
{
switch(state) {
case UNLOCKED:
lock_keystore();
case LOCKED:
return 0;
default:
return -1;
}
}
int unlock(char *passwd)
{
unsigned char master_key[USER_KEY_LEN];
int ret = get_master_key(passwd, master_key);
if (!ret) {
unlock_keystore(master_key);
retry_count = 0;
} else {
ret = MAX_RETRY_COUNT - ++retry_count;
if (ret == 0) {
retry_count = 0;
LOGE("unlock:reach max retry count, reset the keystore now.");
reset_keystore();
return -1;
}
}
return ret;
}
KEYSTORE_STATE get_state()
{
return state;
}
int reset_keystore()
{
DIR *d;
struct dirent *de;
if ((d = opendir(".")) == NULL) {
LOGE("cannot open keystore dir\n");
return -1;
}
while ((de = readdir(d))) unlink(de->d_name);
closedir(d);
state = UNINITIALIZED;
LOGI("keystore is reset.");
return 0;
}
int init_keystore(const char *dir)
{
int fd;
if (!dir) mkdir(dir, 0770);
if (!dir || chdir(dir)) {
LOGE("Can not open/create the keystore directory %s\n",
dir ? dir : "(null)");
return -1;
}
gen_random_blob(iv, IV_LEN);
if ((fd = open(MASTER_KEY, O_RDONLY)) == -1) {
state = UNINITIALIZED;
return 0;
}
close(fd);
state = LOCKED;
return 0;
}