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Merge "Revert "Securely encrypt the master key""

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This commit is contained in:
Paul Lawrence 2015-04-28 19:16:57 +00:00 committed by Gerrit Code Review
commit bf9dcad78e
6 changed files with 4 additions and 458 deletions
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1
Android.mk
View file

@ -15,7 +15,6 @@ common_src_files := \
Devmapper.cpp \
ResponseCode.cpp \
CheckBattery.cpp \
Ext4Crypt.cpp \
VoldUtil.c \
fstrim.c \
cryptfs.c

8
CommandListener.cpp
View file

@ -619,14 +619,6 @@ int CommandListener::CryptfsCmd::runCommand(SocketClient *cli,
Process::killProcessesWithOpenFiles(DATA_MNT_POINT, 2);
}
}
} else if (!strcmp(argv[1], "enablefilecrypto")) {
const char* syntax = "Usage: cryptfs enablefilecrypto";
if (argc != 2) {
cli->sendMsg(ResponseCode::CommandSyntaxError, syntax, false);
return 0;
}
dumpArgs(argc, argv, -1);
rc = cryptfs_enable_file();
} else if (!strcmp(argv[1], "changepw")) {
const char* syntax = "Usage: cryptfs changepw "
"default|password|pin|pattern [newpasswd]";

377
Ext4Crypt.cpp
View file

@ -1,377 +0,0 @@
#include "Ext4Crypt.h"
#include <string>
#include <fstream>
#include <map>
#include <errno.h>
#include <sys/mount.h>
#include <cutils/properties.h>
#include "unencrypted_properties.h"
#include "key_control.h"
#include "cryptfs.h"
#define LOG_TAG "Ext4Crypt"
#include "cutils/log.h"
#include <cutils/klog.h>
namespace {
// Key length in bits
const int key_length = 128;
// How is device encrypted
struct keys {
std::string master_key;
std::string password;
};
std::map<std::string, keys> s_key_store;
// ext4enc:TODO Include structure from somewhere sensible
// MUST be in sync with ext4_crypto.c in kernel
const int EXT4_MAX_KEY_SIZE = 76;
struct ext4_encryption_key {
uint32_t mode;
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 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.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);
}
static UnencryptedProperties GetAltProps(const char* path)
{
return UnencryptedProperties((std::string() + path + "/tmp_mnt").c_str());
}
static UnencryptedProperties GetPropsOrAltProps(const char* path)
{
UnencryptedProperties props = GetProps(path);
if (props.OK()) {
return props;
}
return GetAltProps(path);
}
int e4crypt_enable(const char* path)
{
// Already enabled?
if (s_key_store.find(path) != s_key_store.end()) {
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;
}
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");
// ex4enc:TODO why is this failing?
//return -1;
}
}
if (!UnencryptedProperties(path).Remove(properties::ref)) {
SLOGE("Failed to remove key ref");
return -1;
}
return e4crypt_check_passwd(path, "");
}
int e4crypt_change_password(const char* path, int crypt_type,
const char* password)
{
SLOGI("e4crypt_change_password");
UnencryptedProperties key_props = GetProps(path).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;
}
auto mki = s_key_store.find(path);
if (mki == s_key_store.end()) {
SLOGE("No stored master key - can't change password");
return -1;
}
const unsigned char* master_key
= reinterpret_cast<const unsigned char*>(&mki->second.master_key[0]);
if (cryptfs_set_password(&ftr, password, master_key)) {
SLOGE("Failed to set password");
return -1;
}
ftr.crypt_type = crypt_type;
if (put_crypt_ftr_and_key(ftr, key_props)) {
SLOGE("Failed to write crypto footer");
return -1;
}
if (!UnencryptedProperties(path).Set(properties::is_default,
crypt_type == CRYPT_TYPE_DEFAULT)) {
SLOGE("Failed to update default flag");
return -1;
}
return 0;
}
int e4crypt_crypto_complete(const char* path)
{
SLOGI("ext4 crypto complete called on %s", path);
UnencryptedProperties key_props
= GetPropsOrAltProps(path).GetChild(properties::key);
if (key_props.Get<std::string>(tag::master_key).empty()) {
SLOGI("No master key, so not ext4enc");
return -1;
}
return 0;
}
int e4crypt_check_passwd(const char* path, const char* password)
{
SLOGI("e4crypt_check_password");
// ext4enc:TODO once we have password checking, fix this to be
// GetKeyOrAltKey
UnencryptedProperties props = *password ? GetAltProps(path)
: GetProps(path);
UnencryptedProperties 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[key_length / 8];
if (cryptfs_get_master_key (&ftr, password, master_key)){
SLOGI("Incorrect password");
return -1;
}
s_key_store[path] = keys{std::string(reinterpret_cast<char*>(master_key),
sizeof(master_key)),
password};
// Install password into global keyring
ext4_encryption_key ext4_key = {0, {0}, key_length / 8};
memcpy(ext4_key.raw, master_key, ext4_key.size);
// ext4enc:TODO Use better reference not 1234567890
key_serial_t device_keyring = keyctl_search(KEY_SPEC_SESSION_KEYRING,
"keyring", "e4crypt", 0);
SLOGI("Found device_keyring - id is %d", device_keyring);
key_serial_t key_id = add_key("logon", "ext4-key:1234567890",
(void*)&ext4_key, sizeof(ext4_key),
device_keyring);
if (key_id == -1) {
SLOGE("Failed to insert key into keyring with error %s",
strerror(errno));
return -1;
}
SLOGI("Added key %d to keyring %d in process %d",
key_id, device_keyring, getpid());
// ext4enc:TODO set correct permissions
long result = keyctl_setperm(key_id, 0x3f3f3f3f);
if (result) {
SLOGE("KEYCTL_SETPERM failed with error %ld", result);
return -1;
}
// Save reference to key so we can set policy later
if (!props.Set(properties::ref, "@s.ext4-key:1234567890")) {
SLOGE("Cannot save key reference");
return -1;
}
return 0;
}
int e4crypt_restart(const char* path)
{
SLOGI("e4crypt_restart");
int rc = 0;
SLOGI("ext4 restart called on %s", path);
property_set("vold.decrypt", "trigger_reset_main");
SLOGI("Just asked init to shut down class main");
sleep(2);
std::string tmp_path = std::string() + path + "/tmp_mnt";
// ext4enc:TODO add retry logic
rc = umount(tmp_path.c_str());
if (rc) {
SLOGE("umount %s failed with rc %d, msg %s",
tmp_path.c_str(), rc, strerror(errno));
return rc;
}
// ext4enc:TODO add retry logic
rc = umount(path);
if (rc) {
SLOGE("umount %s failed with rc %d, msg %s",
path, rc, strerror(errno));
return rc;
}
return 0;
}
const char* e4crypt_get_password(const char* path)
{
SLOGI("e4crypt_get_password");
// ext4enc:TODO scrub password after timeout
auto i = s_key_store.find(path);
if (i == s_key_store.end()) {
return 0;
} else {
return i->second.password.c_str();
}
}
int e4crypt_get_password_type(const char* path)
{
SLOGI("e4crypt_get_password_type");
return GetPropsOrAltProps(path).GetChild(properties::key)
.Get<int>(tag::crypt_type, CRYPT_TYPE_DEFAULT);
}

16
Ext4Crypt.h
View file

@ -1,16 +0,0 @@
#include <sys/cdefs.h>
__BEGIN_DECLS
// General functions
int e4crypt_enable(const char* path);
int e4crypt_main(int argc, char* argv[]);
int e4crypt_change_password(const char* path, int crypt_type,
const char* password);
int e4crypt_crypto_complete(const char* path);
int e4crypt_check_passwd(const char* path, const char* password);
int e4crypt_get_password_type(const char* path);
const char* e4crypt_get_password(const char* path);
int e4crypt_restart(const char* path);
__END_DECLS

52
cryptfs.c
View file

@ -53,8 +53,7 @@
#include "VolumeManager.h"
#include "VoldUtil.h"
#include "crypto_scrypt.h"
#include "Ext4Crypt.h"
#include "ext4_crypt_init_extensions.h"
#include "ext4_crypt.h"
#include "ext4_utils.h"
#include "f2fs_sparseblock.h"
#include "CheckBattery.h"
@ -1311,7 +1310,7 @@ 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, KEY_LEN_BYTES)) {
decrypted_master_key, KEY_LEN_BYTES)) {
SLOGE("EVP_EncryptUpdate failed\n");
return -1;
}
@ -1346,7 +1345,7 @@ static int encrypt_master_key(const char *passwd, const unsigned char *salt,
return 0;
}
static int decrypt_master_key_aux(const char *passwd, unsigned char *salt,
static int decrypt_master_key_aux(char *passwd, unsigned char *salt,
unsigned char *encrypted_master_key,
unsigned char *decrypted_master_key,
kdf_func kdf, void *kdf_params,
@ -1411,7 +1410,7 @@ static void get_kdf_func(struct crypt_mnt_ftr *ftr, kdf_func *kdf, void** kdf_pa
}
}
static int decrypt_master_key(const char *passwd, unsigned char *decrypted_master_key,
static int decrypt_master_key(char *passwd, unsigned char *decrypted_master_key,
struct crypt_mnt_ftr *crypt_ftr,
unsigned char** intermediate_key,
size_t* intermediate_key_size)
@ -3805,46 +3804,3 @@ void cryptfs_clear_password()
password_expiry_time = 0;
}
}
int cryptfs_enable_file()
{
return e4crypt_enable(DATA_MNT_POINT);
}
int cryptfs_create_default_ftr(struct crypt_mnt_ftr* crypt_ftr, __attribute__((unused))int key_length)
{
if (cryptfs_init_crypt_mnt_ftr(crypt_ftr)) {
SLOGE("Failed to initialize crypt_ftr");
return -1;
}
if (create_encrypted_random_key(DEFAULT_PASSWORD, crypt_ftr->master_key,
crypt_ftr->salt, crypt_ftr)) {
SLOGE("Cannot create encrypted master key\n");
return -1;
}
//crypt_ftr->keysize = key_length / 8;
return 0;
}
int cryptfs_get_master_key(struct crypt_mnt_ftr* ftr, const char* password,
unsigned char* master_key)
{
int rc;
// ext4enc:TODO check intermediate_key to see if this is valid key
unsigned char* intermediate_key = 0;
size_t intermediate_key_size = 0;
rc = decrypt_master_key(password, master_key, ftr, &intermediate_key,
&intermediate_key_size);
return rc;
}
int cryptfs_set_password(struct crypt_mnt_ftr* ftr, const char* password,
const unsigned char* master_key)
{
return encrypt_master_key(password, ftr->salt, master_key, ftr->master_key,
ftr);
}

8
cryptfs.h
View file

@ -235,7 +235,6 @@ extern "C" {
int cryptfs_enable(char *flag, int type, char *passwd, int allow_reboot);
int cryptfs_changepw(int type, const char *newpw);
int cryptfs_enable_default(char *flag, int allow_reboot);
int cryptfs_enable_file();
int cryptfs_setup_volume(const char *label, int major, int minor,
char *crypto_dev_path, unsigned int max_pathlen,
int *new_major, int *new_minor);
@ -246,13 +245,6 @@ extern "C" {
int cryptfs_get_password_type(void);
const char* cryptfs_get_password(void);
void cryptfs_clear_password(void);
// Functions for file encryption to use to inherit our encryption logic
int cryptfs_create_default_ftr(struct crypt_mnt_ftr* ftr, int key_length);
int cryptfs_get_master_key(struct crypt_mnt_ftr* ftr, const char* password,
unsigned char* master_key);
int cryptfs_set_password(struct crypt_mnt_ftr* ftr, const char* password,
const unsigned char* master_key);
#ifdef __cplusplus
}
#endif