Merge "Securely encrypt the master key"
diff --git a/Android.mk b/Android.mk
index c913a1e..d4a178a 100644
--- a/Android.mk
+++ b/Android.mk
@@ -15,6 +15,7 @@
Devmapper.cpp \
ResponseCode.cpp \
CheckBattery.cpp \
+ Ext4Crypt.cpp \
VoldUtil.c \
fstrim.c \
cryptfs.c
diff --git a/CommandListener.cpp b/CommandListener.cpp
index c66b9d2..73a26e4 100644
--- a/CommandListener.cpp
+++ b/CommandListener.cpp
@@ -619,6 +619,14 @@
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]";
diff --git a/Ext4Crypt.cpp b/Ext4Crypt.cpp
new file mode 100644
index 0000000..84393c9
--- /dev/null
+++ b/Ext4Crypt.cpp
@@ -0,0 +1,377 @@
+#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);
+}
diff --git a/Ext4Crypt.h b/Ext4Crypt.h
new file mode 100644
index 0000000..301639d
--- /dev/null
+++ b/Ext4Crypt.h
@@ -0,0 +1,16 @@
+#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
diff --git a/cryptfs.c b/cryptfs.c
index 91487ed..95b882f 100644
--- a/cryptfs.c
+++ b/cryptfs.c
@@ -53,7 +53,8 @@
#include "VolumeManager.h"
#include "VoldUtil.h"
#include "crypto_scrypt.h"
-#include "ext4_crypt.h"
+#include "Ext4Crypt.h"
+#include "ext4_crypt_init_extensions.h"
#include "ext4_utils.h"
#include "f2fs_sparseblock.h"
#include "CheckBattery.h"
@@ -1310,7 +1311,7 @@
/* 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;
}
@@ -1345,7 +1346,7 @@
return 0;
}
-static int decrypt_master_key_aux(char *passwd, unsigned char *salt,
+static int decrypt_master_key_aux(const char *passwd, unsigned char *salt,
unsigned char *encrypted_master_key,
unsigned char *decrypted_master_key,
kdf_func kdf, void *kdf_params,
@@ -1410,7 +1411,7 @@
}
}
-static int decrypt_master_key(char *passwd, unsigned char *decrypted_master_key,
+static int decrypt_master_key(const char *passwd, unsigned char *decrypted_master_key,
struct crypt_mnt_ftr *crypt_ftr,
unsigned char** intermediate_key,
size_t* intermediate_key_size)
@@ -3804,3 +3805,46 @@
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);
+}
diff --git a/cryptfs.h b/cryptfs.h
index 1da6f94..e149061 100644
--- a/cryptfs.h
+++ b/cryptfs.h
@@ -235,6 +235,7 @@
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);
@@ -245,6 +246,13 @@
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