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Use consistent method for device key

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Change-Id: I420f548115c1b55e62b193c60d569fdda518af1a
gugelfrei
Paul Lawrence 9 years ago
parent 7b6b565fa0
commit aec34dfb1d
1 changed files with 46 additions and 205 deletions
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251
Ext4Crypt.cpp
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@ -55,9 +55,6 @@
#include <android-base/logging.h>
#include <android-base/stringprintf.h>
// TODO - remove when switch to using keymaster keys for device data
static int e4crypt_check_passwd(const char* path, const char* password);
using android::base::StringPrintf;
static bool e4crypt_is_native() {
@ -83,6 +80,7 @@ namespace {
// Some users are ephemeral, don't try to wipe their keys from disk
std::set<userid_t> s_ephemeral_users;
// Map user ids to key references
std::map<userid_t, std::string> s_de_key_raw_refs;
std::map<userid_t, std::string> s_ce_key_raw_refs;
@ -99,173 +97,20 @@ namespace {
char raw[EXT4_MAX_KEY_SIZE];
uint32_t size;
};
namespace tag {
const char* magic = "magic";
const char* major_version = "major_version";
const char* minor_version = "minor_version";
const char* flags = "flags";
const char* crypt_type = "crypt_type";
const char* failed_decrypt_count = "failed_decrypt_count";
const char* crypto_type_name = "crypto_type_name";
const char* master_key = "master_key";
const char* salt = "salt";
const char* kdf_type = "kdf_type";
const char* N_factor = "N_factor";
const char* r_factor = "r_factor";
const char* p_factor = "p_factor";
const char* keymaster_blob = "keymaster_blob";
const char* scrypted_intermediate_key = "scrypted_intermediate_key";
}
}
static bool install_key(const std::string &key, std::string &raw_ref);
static int put_crypt_ftr_and_key(const crypt_mnt_ftr& crypt_ftr,
UnencryptedProperties& props)
{
SLOGI("Putting crypt footer");
bool success = props.Set<int>(tag::magic, crypt_ftr.magic)
&& props.Set<int>(tag::major_version, crypt_ftr.major_version)
&& props.Set<int>(tag::minor_version, crypt_ftr.minor_version)
&& props.Set<int>(tag::flags, crypt_ftr.flags)
&& props.Set<int>(tag::crypt_type, crypt_ftr.crypt_type)
&& props.Set<int>(tag::failed_decrypt_count,
crypt_ftr.failed_decrypt_count)
&& props.Set<std::string>(tag::crypto_type_name,
std::string(reinterpret_cast<const char*>(crypt_ftr.crypto_type_name)))
&& props.Set<std::string>(tag::master_key,
std::string((const char*) crypt_ftr.master_key,
crypt_ftr.keysize))
&& props.Set<std::string>(tag::salt,
std::string((const char*) crypt_ftr.salt,
SALT_LEN))
&& props.Set<int>(tag::kdf_type, crypt_ftr.kdf_type)
&& props.Set<int>(tag::N_factor, crypt_ftr.N_factor)
&& props.Set<int>(tag::r_factor, crypt_ftr.r_factor)
&& props.Set<int>(tag::p_factor, crypt_ftr.p_factor)
&& props.Set<std::string>(tag::keymaster_blob,
std::string((const char*) crypt_ftr.keymaster_blob,
crypt_ftr.keymaster_blob_size))
&& props.Set<std::string>(tag::scrypted_intermediate_key,
std::string((const char*) crypt_ftr.scrypted_intermediate_key,
SCRYPT_LEN));
return success ? 0 : -1;
}
static int get_crypt_ftr_and_key(crypt_mnt_ftr& crypt_ftr,
const UnencryptedProperties& props)
{
memset(&crypt_ftr, 0, sizeof(crypt_ftr));
crypt_ftr.magic = props.Get<int>(tag::magic);
crypt_ftr.major_version = props.Get<int>(tag::major_version);
crypt_ftr.minor_version = props.Get<int>(tag::minor_version);
crypt_ftr.ftr_size = sizeof(crypt_ftr);
crypt_ftr.flags = props.Get<int>(tag::flags);
crypt_ftr.crypt_type = props.Get<int>(tag::crypt_type);
crypt_ftr.failed_decrypt_count = props.Get<int>(tag::failed_decrypt_count);
std::string crypto_type_name = props.Get<std::string>(tag::crypto_type_name);
strlcpy(reinterpret_cast<char*>(crypt_ftr.crypto_type_name),
crypto_type_name.c_str(),
sizeof(crypt_ftr.crypto_type_name));
std::string master_key = props.Get<std::string>(tag::master_key);
crypt_ftr.keysize = master_key.size();
if (crypt_ftr.keysize > sizeof(crypt_ftr.master_key)) {
SLOGE("Master key size too long");
return -1;
}
memcpy(crypt_ftr.master_key, &master_key[0], crypt_ftr.keysize);
std::string salt = props.Get<std::string>(tag::salt);
if (salt.size() != SALT_LEN) {
SLOGE("Salt wrong length");
return -1;
}
memcpy(crypt_ftr.salt, &salt[0], SALT_LEN);
crypt_ftr.kdf_type = props.Get<int>(tag::kdf_type);
crypt_ftr.N_factor = props.Get<int>(tag::N_factor);
crypt_ftr.r_factor = props.Get<int>(tag::r_factor);
crypt_ftr.p_factor = props.Get<int>(tag::p_factor);
std::string keymaster_blob = props.Get<std::string>(tag::keymaster_blob);
crypt_ftr.keymaster_blob_size = keymaster_blob.size();
if (crypt_ftr.keymaster_blob_size > sizeof(crypt_ftr.keymaster_blob)) {
SLOGE("Keymaster blob too long");
return -1;
}
memcpy(crypt_ftr.keymaster_blob, &keymaster_blob[0],
crypt_ftr.keymaster_blob_size);
std::string scrypted_intermediate_key = props.Get<std::string>(tag::scrypted_intermediate_key);
if (scrypted_intermediate_key.size() != SCRYPT_LEN) {
SLOGE("scrypted intermediate key wrong length");
return -1;
}
memcpy(crypt_ftr.scrypted_intermediate_key, &scrypted_intermediate_key[0],
SCRYPT_LEN);
return 0;
}
static UnencryptedProperties GetProps(const char* path)
{
return UnencryptedProperties(path);
}
int e4crypt_enable(const char* path)
{
// Already enabled?
if (s_enabled) {
return 0;
}
// Not an encryptable device?
UnencryptedProperties key_props = GetProps(path).GetChild(properties::key);
if (!key_props.OK()) {
return 0;
}
if (key_props.Get<std::string>(tag::master_key).empty()) {
crypt_mnt_ftr ftr;
if (cryptfs_create_default_ftr(&ftr, key_length)) {
SLOGE("Failed to create crypto footer");
return -1;
}
// Scrub fields not used by ext4enc
ftr.persist_data_offset[0] = 0;
ftr.persist_data_offset[1] = 0;
ftr.persist_data_size = 0;
if (put_crypt_ftr_and_key(ftr, key_props)) {
SLOGE("Failed to write crypto footer");
return -1;
}
crypt_mnt_ftr ftr2;
if (get_crypt_ftr_and_key(ftr2, key_props)) {
SLOGE("Failed to read crypto footer back");
return -1;
}
if (memcmp(&ftr, &ftr2, sizeof(ftr)) != 0) {
SLOGE("Crypto footer not correctly written");
return -1;
}
}
if (!UnencryptedProperties(path).Remove(properties::ref)) {
SLOGE("Failed to remove key ref");
return -1;
}
return e4crypt_check_passwd(path, "");
}
int e4crypt_crypto_complete(const char* path)
{
SLOGI("ext4 crypto complete called on %s", path);
auto key_props = GetProps(path).GetChild(properties::key);
if (key_props.Get<std::string>(tag::master_key).empty()) {
SLOGI("No master key, so not ext4enc");
if (GetProps(path).Get<std::string>(properties::ref).empty()) {
SLOGI("No key reference, so not ext4enc");
return -1;
}
@ -290,53 +135,6 @@ static std::string generate_key_ref(const char* key, int length)
return std::string((char*)key_ref2, EXT4_KEY_DESCRIPTOR_SIZE);
}
static int e4crypt_check_passwd(const char* path, const char* password)
{
SLOGI("e4crypt_check_password");
auto props = GetProps(path);
auto key_props = props.GetChild(properties::key);
crypt_mnt_ftr ftr;
if (get_crypt_ftr_and_key(ftr, key_props)) {
SLOGE("Failed to read crypto footer back");
return -1;
}
unsigned char master_key_bytes[key_length / 8];
if (cryptfs_get_master_key (&ftr, password, master_key_bytes)){
SLOGI("Incorrect password");
ftr.failed_decrypt_count++;
if (put_crypt_ftr_and_key(ftr, key_props)) {
SLOGW("Failed to update failed_decrypt_count");
}
return ftr.failed_decrypt_count;
}
if (ftr.failed_decrypt_count) {
ftr.failed_decrypt_count = 0;
if (put_crypt_ftr_and_key(ftr, key_props)) {
SLOGW("Failed to reset failed_decrypt_count");
}
}
std::string master_key(reinterpret_cast<char*>(master_key_bytes),
sizeof(master_key_bytes));
std::string raw_ref;
if (!install_key(master_key, raw_ref)) {
return -1;
}
SLOGD("Installed master key");
// Save reference to key so we can set policy later
if (!props.Set(properties::ref, raw_ref)) {
SLOGE("Cannot save key reference");
return -1;
}
s_enabled = true;
return 0;
}
static ext4_encryption_key fill_key(const std::string &key)
{
// ext4enc:TODO Currently raw key is required to be of length
@ -569,6 +367,49 @@ static bool load_all_de_keys() {
return true;
}
int e4crypt_enable(const char* path)
{
LOG(INFO) << "e4crypt_enable";
if (s_enabled) {
LOG(INFO) << "Already enabled";
return 0;
}
std::string device_key;
std::string device_key_path = std::string(path) + "/unencrypted/device_key";
if (!android::vold::retrieveKey(device_key_path, device_key)) {
LOG(INFO) << "Creating new key";
if (!random_key(device_key)) {
return -1;
}
if (!android::vold::storeKey(device_key_path, device_key)) {
return -1;
}
}
std::string device_key_ref;
if (!install_key(device_key, device_key_ref)) {
LOG(ERROR) << "Failed to install device key";
return -1;
}
UnencryptedProperties props(path);
if (!props.Remove(properties::ref)) {
SLOGE("Failed to remove key ref");
return -1;
}
if (!props.Set(properties::ref, device_key_ref)) {
SLOGE("Cannot save key reference");
return -1;
}
s_enabled = true;
return 0;
}
int e4crypt_init_user0() {
LOG(DEBUG) << "e4crypt_init_user0";
if (e4crypt_is_native()) {

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