Use a proper key length for the mode.
Bug: 27440526
Change-Id: I818450252dcd39f21948fc2e70856659eba5f50f
diff --git a/Ext4Crypt.cpp b/Ext4Crypt.cpp
index 6612eaf..ffde6a3 100644
--- a/Ext4Crypt.cpp
+++ b/Ext4Crypt.cpp
@@ -58,11 +58,6 @@
static constexpr int FLAG_STORAGE_CE = 1 << 1;
namespace {
- // Key length in bits
- const int key_length = 128;
- static_assert(key_length % 8 == 0,
- "Key length must be multiple of 8 bits");
-
const std::string device_key_dir = std::string() + DATA_MNT_POINT + "/unencrypted";
const std::string device_key_path = device_key_dir + "/key";
const std::string device_key_temp = device_key_dir + "/temp";
@@ -87,8 +82,9 @@
// ext4enc:TODO Include structure from somewhere sensible
// MUST be in sync with ext4_crypto.c in kernel
- const int EXT4_MAX_KEY_SIZE = 64;
- const int EXT4_ENCRYPTION_MODE_AES_256_XTS = 1;
+ constexpr int EXT4_ENCRYPTION_MODE_AES_256_XTS = 1;
+ constexpr int EXT4_AES_256_XTS_KEY_SIZE = 64;
+ constexpr int EXT4_MAX_KEY_SIZE = 64;
struct ext4_encryption_key {
uint32_t mode;
char raw[EXT4_MAX_KEY_SIZE];
@@ -129,19 +125,19 @@
return std::string((char*)key_ref2, EXT4_KEY_DESCRIPTOR_SIZE);
}
-static ext4_encryption_key fill_key(const std::string &key)
+static bool fill_key(const std::string& key, ext4_encryption_key& ext4_key)
{
- // ext4enc:TODO Currently raw key is required to be of length
- // sizeof(ext4_key.raw) == EXT4_MAX_KEY_SIZE, so zero pad to
- // this length. Change when kernel bug is fixed.
- ext4_encryption_key ext4_key = {EXT4_ENCRYPTION_MODE_AES_256_XTS,
- {0},
- sizeof(ext4_key.raw)};
- memset(ext4_key.raw, 0, sizeof(ext4_key.raw));
- static_assert(key_length / 8 <= sizeof(ext4_key.raw),
+ if (key.size() != EXT4_AES_256_XTS_KEY_SIZE) {
+ LOG(ERROR) << "Wrong size key " << key.size();
+ return false;
+ }
+ static_assert(EXT4_AES_256_XTS_KEY_SIZE <= sizeof(ext4_key.raw),
"Key too long!");
- memcpy(ext4_key.raw, &key[0], key.size());
- return ext4_key;
+ ext4_key.mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;
+ ext4_key.size = key.size();
+ memset(ext4_key.raw, 0, sizeof(ext4_key.raw));
+ memcpy(ext4_key.raw, key.data(), key.size());
+ return true;
}
static std::string keyname(const std::string &raw_ref)
@@ -164,11 +160,8 @@
// Return raw key reference for use in policy
static bool install_key(const std::string &key, std::string &raw_ref)
{
- if (key.size() != key_length/8) {
- LOG(ERROR) << "Wrong size key " << key.size();
- return false;
- }
- auto ext4_key = fill_key(key);
+ ext4_encryption_key ext4_key;
+ if (!fill_key(key, ext4_key)) return false;
raw_ref = generate_key_ref(ext4_key.raw, ext4_key.size);
auto ref = keyname(raw_ref);
key_serial_t device_keyring = e4crypt_keyring();
@@ -216,7 +209,7 @@
}
static bool random_key(std::string &key) {
- if (android::vold::ReadRandomBytes(key_length / 8, key) != 0) {
+ if (android::vold::ReadRandomBytes(EXT4_AES_256_XTS_KEY_SIZE, key) != 0) {
// TODO status_t plays badly with PLOG, fix it.
LOG(ERROR) << "Random read failed";
return false;