Clean up providing key via old API
- Use FSCRYPT_MAX_KEY_SIZE from <linux/fscrypt.h> instead of manually
defining FS_AES_256_XTS_KEY_SIZE. These have the same numeric value
(64), but the former is supposed to be used, and AES-256-XTS isn't
necessarily the encryption algorithm that is being used anyway.
- Use the new name FSCRYPT_KEY_DESCRIPTOR_SIZE instead of the old name
FS_KEY_DESCRIPTOR_SIZE. These have the same numeric value (8).
- Don't try to handle sizeof(fscrypt_key::raw) > FSCRYPT_MAX_KEY_SIZE,
as this simply isn't the case.
- Set fscrypt_key::mode to 0 rather than FS_ENCRYPTION_MODE_AES_256_XTS.
This field has always been ignored by the kernel, and AES-256-XTS
isn't necessarily the encryption algorithm that is being used anyway.
- Initialize the fields of fscrypt_key in order.
This is a cleanup only.
Test: booted hikey with fileencryption=aes-256-xts and a kernel that
doesn't support the new fscrypt ioctls.
Bug: none
Change-Id: Ie2a7e9240aa479dfab2765c11db8a7124d20c643
diff --git a/KeyUtil.cpp b/KeyUtil.cpp
index 79a5102..d2d51e1 100644
--- a/KeyUtil.cpp
+++ b/KeyUtil.cpp
@@ -35,10 +35,8 @@
namespace android {
namespace vold {
-constexpr int FS_AES_256_XTS_KEY_SIZE = 64;
-
bool randomKey(KeyBuffer* key) {
- *key = KeyBuffer(FS_AES_256_XTS_KEY_SIZE);
+ *key = KeyBuffer(FSCRYPT_MAX_KEY_SIZE);
if (ReadRandomBytes(key->size(), key->data()) != 0) {
// TODO status_t plays badly with PLOG, fix it.
LOG(ERROR) << "Random read failed";
@@ -97,20 +95,20 @@
unsigned char key_ref2[SHA512_DIGEST_LENGTH];
SHA512_Final(key_ref2, &c);
- static_assert(FS_KEY_DESCRIPTOR_SIZE <= SHA512_DIGEST_LENGTH, "Hash too short for descriptor");
- return std::string((char*)key_ref2, FS_KEY_DESCRIPTOR_SIZE);
+ static_assert(FSCRYPT_KEY_DESCRIPTOR_SIZE <= SHA512_DIGEST_LENGTH,
+ "Hash too short for descriptor");
+ return std::string((char*)key_ref2, FSCRYPT_KEY_DESCRIPTOR_SIZE);
}
static bool fillKey(const KeyBuffer& key, fscrypt_key* fs_key) {
- if (key.size() != FS_AES_256_XTS_KEY_SIZE) {
+ if (key.size() != FSCRYPT_MAX_KEY_SIZE) {
LOG(ERROR) << "Wrong size key " << key.size();
return false;
}
- static_assert(FS_AES_256_XTS_KEY_SIZE <= sizeof(fs_key->raw), "Key too long!");
- fs_key->mode = FS_ENCRYPTION_MODE_AES_256_XTS;
- fs_key->size = key.size();
- memset(fs_key->raw, 0, sizeof(fs_key->raw));
+ static_assert(FSCRYPT_MAX_KEY_SIZE == sizeof(fs_key->raw), "Mismatch of max key sizes");
+ fs_key->mode = 0; // unused by kernel
memcpy(fs_key->raw, key.data(), key.size());
+ fs_key->size = key.size();
return true;
}