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Revert "cryptfs: Optionally get crypt type from properties"

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This reverts commit 291fec1789.
This commit is contained in:
Greg Kaiser 2018-02-14 11:26:00 -08:00
parent 291fec1789
commit fa099611bf
1 changed files with 29 additions and 116 deletions
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145
cryptfs.cpp
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@ -72,6 +72,7 @@ extern "C" {
#define DM_CRYPT_BUF_SIZE 4096
#define HASH_COUNT 2000
#define KEY_LEN_BYTES 16
#define IV_LEN_BYTES 16
#define KEY_IN_FOOTER "footer"
@ -100,11 +101,11 @@ extern "C" {
// EVP_DecryptUpdate() requires not just our key length, but up to
// block length - 1 additional bytes for its work. We provide a buffer
// size that will work for all possible ciphers.
#define DECRYPTED_MASTER_KEY_BUF_SIZE (MAX_KEY_LEN + EVP_MAX_BLOCK_LENGTH - 1)
#define DECRYPTED_MASTER_KEY_BUF_SIZE (KEY_LEN_BYTES + EVP_MAX_BLOCK_LENGTH - 1)
static int put_crypt_ftr_and_key(struct crypt_mnt_ftr* crypt_ftr);
static unsigned char saved_master_key[MAX_KEY_LEN];
static unsigned char saved_master_key[KEY_LEN_BYTES];
static char *saved_mount_point;
static int master_key_saved = 0;
static struct crypt_persist_data *persist_data = NULL;
@ -259,94 +260,6 @@ static void ioctl_init(struct dm_ioctl *io, size_t dataSize, const char *name, u
}
}
namespace {
struct CryptType;
// Use to get the CryptType in use on this device.
const CryptType &get_crypt_type();
struct CryptType {
const char * name;
__le32 keysize;
constexpr CryptType(const char *n, size_t size) : name(n), keysize(size) {}
private:
friend const CryptType &get_crypt_type();
static const CryptType &get_device_crypt_name();
};
// We only want to parse this read-only property once. But we need to wait
// until the system is initialized before we can read it. So we use a static
// scoped within this function to get it only once.
const CryptType &get_crypt_type() {
static CryptType crypt_type = CryptType::get_device_crypt_name();
return crypt_type;
}
__le32 get_keysize() {
return get_crypt_type().keysize;
}
const char *get_crypt_name() {
return get_crypt_type().name;
}
constexpr CryptType default_crypt_type = CryptType("aes-cbc-essiv:sha256", 16);
constexpr CryptType supported_crypt_types[] = {
default_crypt_type,
CryptType("speck128-xts-plain64", 32),
// Add new CryptTypes here. Order is not important.
};
// ---------- START COMPILE-TIME SANITY CHECK BLOCK -------------------------
// We confirm all supported_crypt_types have a small enough keysize.
template <typename T, size_t N>
constexpr size_t array_length(T (&)[N]) { return N; }
constexpr bool indexOutOfBoundsForCryptTypes(size_t index) {
return (index >= array_length(supported_crypt_types));
}
// Note in C++11 that constexpr functions can only have a single line.
// So our code is a bit convoluted (using recursion instead of a loop),
// but it's asserting at compile time that all of our key lengths are valid.
constexpr bool validateSupportedCryptTypes(size_t index) {
return indexOutOfBoundsForCryptTypes(index) ||
((supported_crypt_types[index].keysize <= MAX_KEY_LEN) &&
validateSupportedCryptTypes(index + 1));
}
static_assert(validateSupportedCryptTypes(0),
"We have a CryptType with keysize > MAX_KEYSIZE");
// ---------- END COMPILE-TIME SANITY CHECK BLOCK -------------------------
// Don't call this directly, use get_crypt_type(), which caches this result.
const CryptType &CryptType::get_device_crypt_name() {
constexpr char CRYPT_TYPE_PROP[] = "ro.crypto.crypt_type_name";
char paramstr[PROPERTY_VALUE_MAX];
property_get(CRYPT_TYPE_PROP, paramstr, default_crypt_type.name);
for (auto const &ctype : supported_crypt_types) {
if (strcmp(paramstr, ctype.name) == 0) {
return ctype;
}
}
ALOGE("Invalid name (%s) for %s. Defaulting to %s\n", paramstr,
CRYPT_TYPE_PROP, default_crypt_type.name);
return default_crypt_type;
}
} // namespace
/**
* Gets the default device scrypt parameters for key derivation time tuning.
* The parameters should lead to about one second derivation time for the
@ -938,7 +851,7 @@ static int load_crypto_mapping_table(struct crypt_mnt_ftr *crypt_ftr,
struct dm_ioctl *io;
struct dm_target_spec *tgt;
char *crypt_params;
// We can't assume the key is only get_keysize(). But we do know its limit
// We can't assume the key is only KEY_LEN_BYTES. But we do know its limit
// due to the crypt_mnt_ftr struct. We need two ASCII characters to represent
// each byte, and need space for the '\0' terminator.
char master_key_ascii[sizeof(crypt_ftr->master_key) * 2 + 1];
@ -1135,7 +1048,7 @@ static int pbkdf2(const char *passwd, const unsigned char *salt,
/* Turn the password into a key and IV that can decrypt the master key */
return PKCS5_PBKDF2_HMAC_SHA1(passwd, strlen(passwd), salt, SALT_LEN,
HASH_COUNT, get_keysize() + IV_LEN_BYTES,
HASH_COUNT, KEY_LEN_BYTES + IV_LEN_BYTES,
ikey) != 1;
}
@ -1153,7 +1066,7 @@ static int scrypt(const char *passwd, const unsigned char *salt,
/* Turn the password into a key and IV that can decrypt the master key */
crypto_scrypt((const uint8_t*)passwd, strlen(passwd),
salt, SALT_LEN, N, r, p, ikey,
get_keysize() + IV_LEN_BYTES);
KEY_LEN_BYTES + IV_LEN_BYTES);
return 0;
}
@ -1174,21 +1087,21 @@ static int scrypt_keymaster(const char *passwd, const unsigned char *salt,
rc = crypto_scrypt((const uint8_t*)passwd, strlen(passwd),
salt, SALT_LEN, N, r, p, ikey,
get_keysize() + IV_LEN_BYTES);
KEY_LEN_BYTES + IV_LEN_BYTES);
if (rc) {
SLOGE("scrypt failed");
return -1;
}
if (keymaster_sign_object(ftr, ikey, get_keysize() + IV_LEN_BYTES,
if (keymaster_sign_object(ftr, ikey, KEY_LEN_BYTES + IV_LEN_BYTES,
&signature, &signature_size)) {
SLOGE("Signing failed");
return -1;
}
rc = crypto_scrypt(signature, signature_size, salt, SALT_LEN,
N, r, p, ikey, get_keysize() + IV_LEN_BYTES);
N, r, p, ikey, KEY_LEN_BYTES + IV_LEN_BYTES);
free(signature);
if (rc) {
@ -1204,7 +1117,7 @@ static int encrypt_master_key(const char *passwd, const unsigned char *salt,
unsigned char *encrypted_master_key,
struct crypt_mnt_ftr *crypt_ftr)
{
unsigned char ikey[MAX_KEY_LEN+IV_LEN_BYTES] = { 0 };
unsigned char ikey[KEY_LEN_BYTES+IV_LEN_BYTES] = { 0 };
EVP_CIPHER_CTX e_ctx;
int encrypted_len, final_len;
int rc = 0;
@ -1239,7 +1152,7 @@ static int encrypt_master_key(const char *passwd, const unsigned char *salt,
/* Initialize the decryption engine */
EVP_CIPHER_CTX_init(&e_ctx);
if (! EVP_EncryptInit_ex(&e_ctx, EVP_aes_128_cbc(), NULL, ikey, ikey+get_keysize())) {
if (! EVP_EncryptInit_ex(&e_ctx, EVP_aes_128_cbc(), NULL, ikey, ikey+KEY_LEN_BYTES)) {
SLOGE("EVP_EncryptInit failed\n");
return -1;
}
@ -1247,7 +1160,7 @@ static int encrypt_master_key(const char *passwd, const unsigned char *salt,
/* Encrypt the master key */
if (! EVP_EncryptUpdate(&e_ctx, encrypted_master_key, &encrypted_len,
decrypted_master_key, get_keysize())) {
decrypted_master_key, KEY_LEN_BYTES)) {
SLOGE("EVP_EncryptUpdate failed\n");
return -1;
}
@ -1256,7 +1169,7 @@ static int encrypt_master_key(const char *passwd, const unsigned char *salt,
return -1;
}
if (encrypted_len + final_len != static_cast<int>(get_keysize())) {
if (encrypted_len + final_len != KEY_LEN_BYTES) {
SLOGE("EVP_Encryption length check failed with %d, %d bytes\n", encrypted_len, final_len);
return -1;
}
@ -1270,7 +1183,7 @@ static int encrypt_master_key(const char *passwd, const unsigned char *salt,
int r = 1 << crypt_ftr->r_factor;
int p = 1 << crypt_ftr->p_factor;
rc = crypto_scrypt(ikey, get_keysize(),
rc = crypto_scrypt(ikey, KEY_LEN_BYTES,
crypt_ftr->salt, sizeof(crypt_ftr->salt), N, r, p,
crypt_ftr->scrypted_intermediate_key,
sizeof(crypt_ftr->scrypted_intermediate_key));
@ -1291,7 +1204,7 @@ static int decrypt_master_key_aux(const char *passwd, unsigned char *salt,
unsigned char** intermediate_key,
size_t* intermediate_key_size)
{
unsigned char ikey[MAX_KEY_LEN+IV_LEN_BYTES] = { 0 };
unsigned char ikey[KEY_LEN_BYTES+IV_LEN_BYTES] = { 0 };
EVP_CIPHER_CTX d_ctx;
int decrypted_len, final_len;
@ -1304,29 +1217,29 @@ static int decrypt_master_key_aux(const char *passwd, unsigned char *salt,
/* Initialize the decryption engine */
EVP_CIPHER_CTX_init(&d_ctx);
if (! EVP_DecryptInit_ex(&d_ctx, EVP_aes_128_cbc(), NULL, ikey, ikey+get_keysize())) {
if (! EVP_DecryptInit_ex(&d_ctx, EVP_aes_128_cbc(), NULL, ikey, ikey+KEY_LEN_BYTES)) {
return -1;
}
EVP_CIPHER_CTX_set_padding(&d_ctx, 0); /* Turn off padding as our data is block aligned */
/* Decrypt the master key */
if (! EVP_DecryptUpdate(&d_ctx, decrypted_master_key, &decrypted_len,
encrypted_master_key, get_keysize())) {
encrypted_master_key, KEY_LEN_BYTES)) {
return -1;
}
if (! EVP_DecryptFinal_ex(&d_ctx, decrypted_master_key + decrypted_len, &final_len)) {
return -1;
}
if (decrypted_len + final_len != static_cast<int>(get_keysize())) {
if (decrypted_len + final_len != KEY_LEN_BYTES) {
return -1;
}
/* Copy intermediate key if needed by params */
if (intermediate_key && intermediate_key_size) {
*intermediate_key = (unsigned char*) malloc(get_keysize());
*intermediate_key = (unsigned char*) malloc(KEY_LEN_BYTES);
if (*intermediate_key) {
memcpy(*intermediate_key, ikey, get_keysize());
*intermediate_key_size = get_keysize();
memcpy(*intermediate_key, ikey, KEY_LEN_BYTES);
*intermediate_key_size = KEY_LEN_BYTES;
}
}
@ -1372,7 +1285,7 @@ static int decrypt_master_key(const char *passwd, unsigned char *decrypted_maste
static int create_encrypted_random_key(const char *passwd, unsigned char *master_key, unsigned char *salt,
struct crypt_mnt_ftr *crypt_ftr) {
int fd;
unsigned char key_buf[MAX_KEY_LEN];
unsigned char key_buf[KEY_LEN_BYTES];
/* Get some random bits for a key */
fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC);
@ -1770,7 +1683,7 @@ static int test_mount_encrypted_fs(struct crypt_mnt_ftr* crypt_ftr,
/* Also save a the master key so we can reencrypted the key
* the key when we want to change the password on it. */
memcpy(saved_master_key, decrypted_master_key, get_keysize());
memcpy(saved_master_key, decrypted_master_key, KEY_LEN_BYTES);
saved_mount_point = strdup(mount_point);
master_key_saved = 1;
SLOGD("%s(): Master key saved\n", __FUNCTION__);
@ -1845,7 +1758,7 @@ int cryptfs_setup_ext_volume(const char* label, const char* real_blkdev,
memset(&ext_crypt_ftr, 0, sizeof(ext_crypt_ftr));
ext_crypt_ftr.fs_size = nr_sec;
ext_crypt_ftr.keysize = keysize;
strlcpy((char*) ext_crypt_ftr.crypto_type_name, get_crypt_name(),
strlcpy((char*) ext_crypt_ftr.crypto_type_name, "aes-cbc-essiv:sha256",
MAX_CRYPTO_TYPE_NAME_LEN);
return create_crypto_blk_dev(
@ -1988,7 +1901,7 @@ int cryptfs_verify_passwd(const char *passwd)
}
/* Initialize a crypt_mnt_ftr structure. The keysize is
* defaulted to get_keysize(), and the filesystem size to 0.
* defaulted to 16 bytes, and the filesystem size to 0.
* Presumably, at a minimum, the caller will update the
* filesystem size and crypto_type_name after calling this function.
*/
@ -2001,7 +1914,7 @@ static int cryptfs_init_crypt_mnt_ftr(struct crypt_mnt_ftr *ftr)
ftr->major_version = CURRENT_MAJOR_VERSION;
ftr->minor_version = CURRENT_MINOR_VERSION;
ftr->ftr_size = sizeof(struct crypt_mnt_ftr);
ftr->keysize = get_keysize();
ftr->keysize = KEY_LEN_BYTES;
switch (keymaster_check_compatibility()) {
case 1:
@ -2253,7 +2166,7 @@ int cryptfs_enable_internal(int crypt_type, const char* passwd, int no_ui) {
crypt_ftr.flags |= CRYPT_INCONSISTENT_STATE;
}
crypt_ftr.crypt_type = crypt_type;
strlcpy((char *)crypt_ftr.crypto_type_name, get_crypt_name(), MAX_CRYPTO_TYPE_NAME_LEN);
strlcpy((char *)crypt_ftr.crypto_type_name, "aes-cbc-essiv:sha256", MAX_CRYPTO_TYPE_NAME_LEN);
/* Make an encrypted master key */
if (create_encrypted_random_key(onlyCreateHeader ? DEFAULT_PASSWORD : passwd,
@ -2264,8 +2177,8 @@ int cryptfs_enable_internal(int crypt_type, const char* passwd, int no_ui) {
/* Replace scrypted intermediate key if we are preparing for a reboot */
if (onlyCreateHeader) {
unsigned char fake_master_key[MAX_KEY_LEN];
unsigned char encrypted_fake_master_key[MAX_KEY_LEN];
unsigned char fake_master_key[KEY_LEN_BYTES];
unsigned char encrypted_fake_master_key[KEY_LEN_BYTES];
memset(fake_master_key, 0, sizeof(fake_master_key));
encrypt_master_key(passwd, crypt_ftr.salt, fake_master_key,
encrypted_fake_master_key, &crypt_ftr);