373 lines
9.8 KiB
C
373 lines
9.8 KiB
C
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/*
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** Copyright 2009, The Android Open Source Project
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**
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** Licensed under the Apache License, Version 2.0 (the "License");
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** you may not use this file except in compliance with the License.
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** You may obtain a copy of the License at
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**
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** http://www.apache.org/licenses/LICENSE-2.0
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**
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** Unless required by applicable law or agreed to in writing, software
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** distributed under the License is distributed on an "AS IS" BASIS,
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** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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** See the License for the specific language governing permissions and
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** limitations under the License.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <ctype.h>
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#include <fcntl.h>
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#include <dirent.h>
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#include <errno.h>
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#include <openssl/aes.h>
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#include <openssl/evp.h>
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#include <cutils/log.h>
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#include "common.h"
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#include "keymgmt.h"
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static int retry_count = 0;
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static unsigned char iv[IV_LEN];
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static KEYSTORE_STATE state = BOOTUP;
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static AES_KEY encryptKey, decryptKey;
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inline void unlock_keystore(unsigned char *master_key)
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{
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AES_set_encrypt_key(master_key, AES_KEY_LEN, &encryptKey);
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AES_set_decrypt_key(master_key, AES_KEY_LEN, &decryptKey);
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memset(master_key, 0, sizeof(master_key));
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state = UNLOCKED;
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}
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inline void lock_keystore()
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{
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memset(&encryptKey, 0 , sizeof(AES_KEY));
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memset(&decryptKey, 0 , sizeof(AES_KEY));
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state = LOCKED;
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}
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inline void get_encrypt_key(char *passwd, AES_KEY *key)
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{
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unsigned char user_key[USER_KEY_LEN];
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gen_key(passwd, user_key, USER_KEY_LEN);
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AES_set_encrypt_key(user_key, AES_KEY_LEN, key);
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}
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inline void get_decrypt_key(char *passwd, AES_KEY *key)
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{
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unsigned char user_key[USER_KEY_LEN];
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gen_key(passwd, user_key, USER_KEY_LEN);
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AES_set_decrypt_key(user_key, AES_KEY_LEN, key);
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}
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static int gen_random_blob(unsigned char *key, int size)
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{
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int ret = 0;
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int fd = open("/dev/urandom", O_RDONLY);
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if (fd == -1) return -1;
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if (read(fd, key, size) != size) ret = -1;
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close(fd);
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return ret;
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}
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static int encrypt_n_save(AES_KEY *enc_key, DATA_BLOB *blob,
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const char *keyfile)
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{
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int size, fd, ret = -1;
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unsigned char enc_blob[MAX_BLOB_LEN];
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char tmpfile[KEYFILE_LEN];
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strcpy(tmpfile, keyfile);
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strcat(tmpfile, ".tmp");
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// prepare the blob
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memcpy(blob->iv, iv, IV_LEN);
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blob->blob_size = get_blob_size(blob);
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memcpy(enc_blob, blob->blob, blob->blob_size);
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AES_cbc_encrypt((unsigned char *)enc_blob, (unsigned char *)blob->blob,
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blob->blob_size, enc_key, iv, AES_ENCRYPT);
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// write to keyfile
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size = data_blob_size(blob);
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if ((fd = open(tmpfile, O_CREAT|O_RDWR)) == -1) return -1;
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if (write(fd, blob, size) == size) ret = 0;
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close(fd);
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if (!ret) {
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unlink(keyfile);
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rename(tmpfile, keyfile);
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chmod(keyfile, 0440);
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}
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return ret;
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}
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static int load_n_decrypt(const char *keyname, const char *keyfile,
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AES_KEY *key, DATA_BLOB *blob)
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{
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int fd, ret = -1;
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if ((fd = open(keyfile, O_RDONLY)) == -1) return -1;
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// get the encrypted blob and iv
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if ((read(fd, blob->iv, sizeof(blob->iv)) != sizeof(blob->iv)) ||
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(read(fd, &blob->blob_size, sizeof(uint32_t)) != sizeof(uint32_t)) ||
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(blob->blob_size > MAX_BLOB_LEN)) {
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goto err;
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} else {
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unsigned char enc_blob[MAX_BLOB_LEN];
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if (read(fd, enc_blob, blob->blob_size) !=
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(int) blob->blob_size) goto err;
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// decrypt the blob
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AES_cbc_encrypt((unsigned char *)enc_blob, (unsigned char*)blob->blob,
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blob->blob_size, key, blob->iv, AES_DECRYPT);
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if (strcmp(keyname, (char*)blob->keyname) == 0) ret = 0;
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}
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err:
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close(fd);
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return ret;
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}
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static int store_master_key(char *upasswd, unsigned char *master_key)
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{
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AES_KEY key;
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DATA_BLOB blob;
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// prepare the blob
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strlcpy(blob.keyname, MASTER_KEY_TAG, USER_KEY_LEN);
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blob.value_size = USER_KEY_LEN;
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memcpy((void*)blob.value, (const void*)master_key, USER_KEY_LEN);
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// generate the encryption key
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get_encrypt_key(upasswd, &key);
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return encrypt_n_save(&key, &blob, MASTER_KEY);
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}
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static int get_master_key(char *upasswd, unsigned char *master_key)
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{
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AES_KEY key;
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int size, ret = 0;
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DATA_BLOB blob;
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get_decrypt_key(upasswd, &key);
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ret = load_n_decrypt(MASTER_KEY_TAG, MASTER_KEY, &key, &blob);
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if (!ret) memcpy(master_key, blob.value, blob.value_size);
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return ret;
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}
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static int create_master_key(char *upasswd)
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{
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int ret;
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unsigned char mpasswd[AES_KEY_LEN];
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unsigned char master_key[USER_KEY_LEN];
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gen_random_blob(mpasswd, AES_KEY_LEN);
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gen_key((char*)mpasswd, master_key, USER_KEY_LEN);
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if ((ret = store_master_key(upasswd, master_key)) == 0) {
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unlock_keystore(master_key);
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}
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memset(master_key, 0, USER_KEY_LEN);
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memset(mpasswd, 0, AES_KEY_LEN);
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return ret;
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}
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static int change_passwd(char *data)
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{
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unsigned char master_key[USER_KEY_LEN];
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char *old_pass, *new_pass = NULL, *p, *delimiter=" ";
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int ret, count = 0;
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char *context = NULL;
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old_pass = p = strtok_r(data, delimiter, &context);
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while (p != NULL) {
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count++;
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new_pass = p;
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p = strtok_r(NULL, delimiter, &context);
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}
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if (count != 2) return -1;
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if (strlen(new_pass) < MIN_PASSWD_LENGTH) return -1;
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if ((ret = get_master_key(old_pass, master_key)) == 0) {
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ret = store_master_key(new_pass, master_key);
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retry_count = 0;
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} else {
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ret = MAX_RETRY_COUNT - ++retry_count;
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if (ret == 0) {
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retry_count = 0;
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LOGE("passwd:reach max retry count, reset the keystore now.");
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reset_keystore();
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return -1;
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}
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}
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return ret;
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}
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int remove_key(const char *namespace, const char *keyname)
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{
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char keyfile[KEYFILE_LEN];
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if (state != UNLOCKED) return -state;
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sprintf(keyfile, KEYFILE_NAME, namespace, keyname);
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return unlink(keyfile);
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}
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int put_key(const char *namespace, const char *keyname,
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unsigned char *data, int size)
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{
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DATA_BLOB blob;
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uint32_t real_size;
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char keyfile[KEYFILE_LEN];
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if (state != UNLOCKED) {
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LOGE("Can not store key with current state %d\n", state);
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return -state;
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}
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sprintf(keyfile, KEYFILE_NAME, namespace, keyname);
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// flatten the args
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strcpy(blob.keyname, keyname);
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blob.value_size = size;
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memcpy(blob.value, data, size);
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return encrypt_n_save(&encryptKey, &blob, keyfile);
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}
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int get_key(const char *namespace, const char *keyname,
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unsigned char *data, int *size)
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{
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int ret;
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DATA_BLOB blob;
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uint32_t blob_size;
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char keyfile[KEYFILE_LEN];
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if (state != UNLOCKED) {
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LOGE("Can not retrieve key value with current state %d\n", state);
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return -state;
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}
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sprintf(keyfile, KEYFILE_NAME, namespace, keyname);
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ret = load_n_decrypt(keyname, keyfile, &decryptKey, &blob);
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if (!ret) {
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if ((blob.value_size > MAX_KEY_VALUE_LENGTH)) {
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ret = -1;
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} else {
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*size = blob.value_size;
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memcpy(data, blob.value, *size);
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}
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}
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return ret;
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}
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int list_keys(const char *namespace, char reply[BUFFER_MAX])
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{
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DIR *d;
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struct dirent *de;
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if (state != UNLOCKED) {
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LOGE("Can not list key with current state %d\n", state);
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return -1;
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}
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if (!namespace || ((d = opendir("."))) == NULL) {
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LOGE("cannot open keystore dir or namespace is null\n");
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return -1;
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}
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while ((de = readdir(d))) {
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char *prefix, *name, *keyfile = de->d_name;
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char *context = NULL;
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if (de->d_type != DT_REG) continue;
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if ((prefix = strtok_r(keyfile, NAME_DELIMITER, &context))
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== NULL) continue;
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if (strcmp(prefix, namespace)) continue;
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if ((name = strtok_r(NULL, NAME_DELIMITER, &context)) == NULL) continue;
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// append the key name into reply
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if (reply[0] != 0) strlcat(reply, " ", BUFFER_MAX);
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if (strlcat(reply, name, BUFFER_MAX) >= BUFFER_MAX) {
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LOGE("too many files under keystore directory\n");
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return -1;
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}
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}
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closedir(d);
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return 0;
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}
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int passwd(char *data)
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{
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if (state == UNINITIALIZED) {
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if (strchr(data, ' ')) return -1;
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if (strlen(data) < MIN_PASSWD_LENGTH) return -1;
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return create_master_key(data);
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}
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return change_passwd(data);
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}
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int lock()
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{
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switch(state) {
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case UNLOCKED:
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lock_keystore();
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case LOCKED:
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return 0;
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default:
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return -1;
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}
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}
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int unlock(char *passwd)
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{
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unsigned char master_key[USER_KEY_LEN];
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int ret = get_master_key(passwd, master_key);
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if (!ret) {
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unlock_keystore(master_key);
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retry_count = 0;
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} else {
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ret = MAX_RETRY_COUNT - ++retry_count;
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if (ret == 0) {
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retry_count = 0;
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LOGE("unlock:reach max retry count, reset the keystore now.");
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reset_keystore();
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return -1;
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}
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}
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return ret;
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}
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KEYSTORE_STATE get_state()
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{
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return state;
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}
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int reset_keystore()
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{
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DIR *d;
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struct dirent *de;
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if ((d = opendir(".")) == NULL) {
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LOGE("cannot open keystore dir\n");
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return -1;
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}
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while ((de = readdir(d))) unlink(de->d_name);
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closedir(d);
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state = UNINITIALIZED;
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LOGI("keystore is reset.");
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return 0;
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}
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int init_keystore(const char *dir)
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{
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int fd;
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if (!dir) mkdir(dir, 0770);
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if (!dir || chdir(dir)) {
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LOGE("Can not open/create the keystore directory %s\n",
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dir ? dir : "(null)");
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return -1;
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}
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gen_random_blob(iv, IV_LEN);
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if ((fd = open(MASTER_KEY, O_RDONLY)) == -1) {
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state = UNINITIALIZED;
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return 0;
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}
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close(fd);
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state = LOCKED;
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return 0;
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}
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