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Add fileencrypted=software/ice to fstab options

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Bug: 28616054
Change-Id: If3fddd62f069c7e3e8369a1db68e69c390059d63
This commit is contained in:
Paul Lawrence 2016-05-05 11:02:07 -07:00
parent 44ddebaac0
commit 01f1bc7254
3 changed files with 223 additions and 0 deletions
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5
CryptCommandListener.cpp
View file

@ -410,6 +410,11 @@ int CryptCommandListener::CryptfsCmd::runCommand(SocketClient *cli,
return sendGenericOkFailOnBool(cli,
e4crypt_destroy_user_storage(parseNull(argv[2]), atoi(argv[3]), atoi(argv[4])));
} else if (subcommand == "ensure_policy") {
if (!check_argc(cli, subcommand, argc, 4, "<dir> <policy>")) return 0;
return sendGenericOkFailOnBool(cli,
e4crypt_hex_policy_ensure(argv[2], argv[3]));
} else {
dumpArgs(argc, argv, -1);
cli->sendMsg(ResponseCode::CommandSyntaxError, "Unknown cryptfs subcommand", false);

217
Ext4Crypt.cpp
View file

@ -37,6 +37,8 @@
#include <private/android_filesystem_config.h>
#include <fs_mgr.h>
#include "cryptfs.h"
#include "ext4_crypt.h"
#include "key_control.h"
@ -57,6 +59,9 @@ using android::vold::kEmptyAuthentication;
static constexpr int FLAG_STORAGE_DE = 1 << 0;
static constexpr int FLAG_STORAGE_CE = 1 << 1;
// Vile hack to get fstab entries for file encryption type
extern struct fstab *fstab;
namespace {
const std::string device_key_dir = std::string() + DATA_MNT_POINT + e4crypt_unencrypted_folder;
const std::string device_key_path = device_key_dir + "/key";
@ -92,6 +97,218 @@ struct ext4_encryption_key {
};
}
#define XATTR_NAME_ENCRYPTION_POLICY "encryption.policy"
#define EXT4_KEYREF_DELIMITER ((char)'.')
// ext4enc:TODO Include structure from somewhere sensible
// MUST be in sync with ext4_crypto.c in kernel
#define EXT4_KEY_DESCRIPTOR_SIZE 8
#define EXT4_KEY_DESCRIPTOR_SIZE_HEX 17
struct ext4_encryption_policy {
char version;
char contents_encryption_mode;
char filenames_encryption_mode;
char flags;
char master_key_descriptor[EXT4_KEY_DESCRIPTOR_SIZE];
} __attribute__((__packed__));
#define EXT4_ENCRYPTION_MODE_AES_256_XTS 1
#define EXT4_ENCRYPTION_MODE_AES_256_CTS 4
#define EXT4_ENCRYPTION_MODE_PRIVATE 127
// ext4enc:TODO Get value from somewhere sensible
#define EXT4_IOC_SET_ENCRYPTION_POLICY _IOR('f', 19, struct ext4_encryption_policy)
#define EXT4_IOC_GET_ENCRYPTION_POLICY _IOW('f', 21, struct ext4_encryption_policy)
#define HEX_LOOKUP "0123456789abcdef"
static void policy_to_hex(const char* policy, char* hex) {
for (size_t i = 0, j = 0; i < EXT4_KEY_DESCRIPTOR_SIZE; i++) {
hex[j++] = HEX_LOOKUP[(policy[i] & 0xF0) >> 4];
hex[j++] = HEX_LOOKUP[policy[i] & 0x0F];
}
hex[EXT4_KEY_DESCRIPTOR_SIZE_HEX - 1] = '\0';
}
static bool is_dir_empty(const char *dirname, bool *is_empty)
{
int n = 0;
auto dirp = std::unique_ptr<DIR, int (*)(DIR*)>(opendir(dirname), closedir);
if (!dirp) {
PLOG(ERROR) << "Unable to read directory: " << dirname;
return false;
}
for (;;) {
errno = 0;
auto entry = readdir(dirp.get());
if (!entry) {
if (errno) {
PLOG(ERROR) << "Unable to read directory: " << dirname;
return false;
}
break;
}
if (strcmp(entry->d_name, "lost+found") != 0) { // Skip lost+found
++n;
if (n > 2) {
*is_empty = false;
return true;
}
}
}
*is_empty = true;
return true;
}
static bool e4crypt_policy_set(const char *directory, const char *policy,
size_t policy_length, int contents_encryption_type) {
if (policy_length != EXT4_KEY_DESCRIPTOR_SIZE) {
LOG(ERROR) << "Policy wrong length: " << policy_length;
return false;
}
int fd = open(directory, O_DIRECTORY | O_NOFOLLOW | O_CLOEXEC);
if (fd == -1) {
PLOG(ERROR) << "Failed to open directory " << directory;
return false;
}
ext4_encryption_policy eep;
eep.version = 0;
eep.contents_encryption_mode = contents_encryption_type;
eep.filenames_encryption_mode = EXT4_ENCRYPTION_MODE_AES_256_CTS;
eep.flags = 0;
memcpy(eep.master_key_descriptor, policy, EXT4_KEY_DESCRIPTOR_SIZE);
if (ioctl(fd, EXT4_IOC_SET_ENCRYPTION_POLICY, &eep)) {
PLOG(ERROR) << "Failed to set encryption policy for " << directory;
close(fd);
return false;
}
close(fd);
char policy_hex[EXT4_KEY_DESCRIPTOR_SIZE_HEX];
policy_to_hex(policy, policy_hex);
LOG(INFO) << "Policy for " << directory << " set to " << policy_hex;
return true;
}
static bool e4crypt_policy_get(const char *directory, char *policy,
size_t policy_length, int contents_encryption_type) {
if (policy_length != EXT4_KEY_DESCRIPTOR_SIZE) {
LOG(ERROR) << "Policy wrong length: " << policy_length;
return false;
}
int fd = open(directory, O_DIRECTORY | O_NOFOLLOW | O_CLOEXEC);
if (fd == -1) {
PLOG(ERROR) << "Failed to open directory " << directory;
return false;
}
ext4_encryption_policy eep;
memset(&eep, 0, sizeof(ext4_encryption_policy));
if (ioctl(fd, EXT4_IOC_GET_ENCRYPTION_POLICY, &eep) != 0) {
PLOG(ERROR) << "Failed to get encryption policy for " << directory;
close(fd);
return -1;
}
close(fd);
if ((eep.version != 0)
|| (eep.contents_encryption_mode != contents_encryption_type)
|| (eep.filenames_encryption_mode != EXT4_ENCRYPTION_MODE_AES_256_CTS)
|| (eep.flags != 0)) {
LOG(ERROR) << "Failed to find matching encryption policy for " << directory;
return false;
}
memcpy(policy, eep.master_key_descriptor, EXT4_KEY_DESCRIPTOR_SIZE);
return true;
}
static bool e4crypt_policy_check(const char *directory, const char *policy,
size_t policy_length, int contents_encryption_type) {
if (policy_length != EXT4_KEY_DESCRIPTOR_SIZE) {
LOG(ERROR) << "Policy wrong length: " << policy_length;
return false;
}
char existing_policy[EXT4_KEY_DESCRIPTOR_SIZE];
if (!e4crypt_policy_get(directory, existing_policy, EXT4_KEY_DESCRIPTOR_SIZE,
contents_encryption_type)) {
return false;
}
char existing_policy_hex[EXT4_KEY_DESCRIPTOR_SIZE_HEX];
policy_to_hex(existing_policy, existing_policy_hex);
if (memcmp(policy, existing_policy, EXT4_KEY_DESCRIPTOR_SIZE) != 0) {
char policy_hex[EXT4_KEY_DESCRIPTOR_SIZE_HEX];
policy_to_hex(policy, policy_hex);
LOG(ERROR) << "Found policy " << existing_policy_hex << " at " << directory
<< " which doesn't match expected value " << policy_hex;
return false;
}
LOG(INFO) << "Found policy " << existing_policy_hex << " at " << directory
<< " which matches expected value";
return true;
}
int e4crypt_policy_ensure(const char* directory, const char* policy, int policy_length)
{
static int contents_encryption_type = 0;
if (contents_encryption_type == 0) {
// Get file_encryption_type from fstab
struct fstab_rec *rec = fs_mgr_get_entry_for_mount_point(fstab, "/data");
if (rec == 0) {
return -1;
}
// Translate file_encryption_type to ext4 contents encryption type
switch (rec->file_encryption_type)
{
case ET_SOFTWARE:
contents_encryption_type = EXT4_ENCRYPTION_MODE_AES_256_XTS;
break;
case ET_ICE:
contents_encryption_type = EXT4_ENCRYPTION_MODE_PRIVATE;
break;
default:
return -1;
}
}
bool is_empty;
if (!is_dir_empty(directory, &is_empty)) return -1;
if (is_empty) {
if (!e4crypt_policy_set(directory, policy, policy_length,
contents_encryption_type)) {
return -1;
}
} else {
if (!e4crypt_policy_check(directory, policy, policy_length,
contents_encryption_type)) {
return -1;
}
}
return 0;
}
bool e4crypt_hex_policy_ensure(const char* dir, const char* hex_policy)
{
std::string hex = hex_policy;
if (hex.substr(0, 2) != "0x") {
return false;
}
std::string policy;
if (android::vold::HexToStr(hex.substr(2), policy)) {
return false;
}
return e4crypt_policy_ensure(dir, policy.c_str(), policy.length()) == 0;
}
static bool e4crypt_is_emulated() {
return property_get_bool("persist.sys.emulate_fbe", false);
}

1
Ext4Crypt.h
View file

@ -36,5 +36,6 @@ bool e4crypt_lock_user_key(userid_t user_id);
bool e4crypt_prepare_user_storage(const char* volume_uuid, userid_t user_id, int serial, int flags);
bool e4crypt_destroy_user_storage(const char* volume_uuid, userid_t user_id, int flags);
bool e4crypt_hex_policy_ensure(const char* dir, const char* hex_policy);
__END_DECLS