| #define TAG "ext4_utils" |
| |
| #include "ext4_crypt.h" |
| |
| #include <string> |
| #include <fstream> |
| #include <iomanip> |
| #include <sstream> |
| |
| #include <errno.h> |
| #include <sys/mount.h> |
| #include <sys/stat.h> |
| |
| #include <cutils/klog.h> |
| #include <cutils/properties.h> |
| #include <cutils/sockets.h> |
| #include <poll.h> |
| |
| #include "unencrypted_properties.h" |
| |
| // ext4enc:TODO Include structure from somewhere sensible |
| // MUST be in sync with ext4_crypto.c in kernel |
| #define EXT4_MAX_KEY_SIZE 76 |
| struct ext4_encryption_key { |
| uint32_t mode; |
| char raw[EXT4_MAX_KEY_SIZE]; |
| uint32_t size; |
| }; |
| |
| static const std::string keyring = "@s"; |
| static const std::string arbitrary_sequence_number = "42"; |
| static const int vold_command_timeout_ms = 10 * 1000; |
| |
| static key_serial_t device_keyring = -1; |
| |
| static std::string vold_command(std::string const& command) |
| { |
| KLOG_INFO(TAG, "Running command %s\n", command.c_str()); |
| int sock = socket_local_client("vold", |
| ANDROID_SOCKET_NAMESPACE_RESERVED, |
| SOCK_STREAM); |
| |
| if (sock < 0) { |
| KLOG_INFO(TAG, "Cannot open vold, failing command\n"); |
| return ""; |
| } |
| |
| class CloseSocket |
| { |
| int sock_; |
| public: |
| CloseSocket(int sock) : sock_(sock) {} |
| ~CloseSocket() { close(sock_); } |
| }; |
| |
| CloseSocket cs(sock); |
| |
| // Use arbitrary sequence number. This should only be used when the |
| // framework is down, so this is (mostly) OK. |
| std::string actual_command = arbitrary_sequence_number + " " + command; |
| if (write(sock, actual_command.c_str(), actual_command.size() + 1) < 0) { |
| KLOG_ERROR(TAG, "Cannot write command\n"); |
| return ""; |
| } |
| |
| struct pollfd poll_sock = {sock, POLLIN, 0}; |
| |
| int rc = poll(&poll_sock, 1, vold_command_timeout_ms); |
| if (rc < 0) { |
| KLOG_ERROR(TAG, "Error in poll %s\n", strerror(errno)); |
| return ""; |
| } |
| if (!(poll_sock.revents & POLLIN)) { |
| KLOG_ERROR(TAG, "Timeout\n"); |
| return ""; |
| } |
| char buffer[4096]; |
| memset(buffer, 0, sizeof(buffer)); |
| rc = read(sock, buffer, sizeof(buffer)); |
| if (rc <= 0) { |
| if (rc == 0) { |
| KLOG_ERROR(TAG, "Lost connection to Vold - did it crash?\n"); |
| } else { |
| KLOG_ERROR(TAG, "Error reading data (%s)\n", strerror(errno)); |
| } |
| return ""; |
| } |
| |
| // We don't truly know that this is the correct result. However, |
| // since this will only be used when the framework is down, |
| // it should be OK unless someone is running vdc at the same time. |
| // Worst case we force a reboot in the very rare synchronization |
| // error |
| return std::string(buffer, rc); |
| } |
| |
| int e4crypt_create_device_key(const char* dir, |
| int ensure_dir_exists(const char*)) |
| { |
| // Make sure folder exists. Use make_dir to set selinux permissions. |
| KLOG_INFO(TAG, "Creating test device key\n"); |
| UnencryptedProperties props(dir); |
| if (ensure_dir_exists(props.GetPath().c_str())) { |
| KLOG_ERROR(TAG, "Failed to create %s with error %s\n", |
| props.GetPath().c_str(), strerror(errno)); |
| return -1; |
| } |
| |
| if (props.Get<std::string>(properties::key).empty()) { |
| // Create new key since it doesn't already exist |
| std::ifstream urandom("/dev/urandom", std::ifstream::binary); |
| if (!urandom) { |
| KLOG_ERROR(TAG, "Failed to open /dev/urandom\n"); |
| return -1; |
| } |
| |
| // ext4enc:TODO Don't hardcode 32 |
| std::string key_material(32, '\0'); |
| urandom.read(&key_material[0], key_material.length()); |
| if (!urandom) { |
| KLOG_ERROR(TAG, "Failed to read random bytes\n"); |
| return -1; |
| } |
| |
| if (!props.Set(properties::key, key_material)) { |
| KLOG_ERROR(TAG, "Failed to write key material\n"); |
| return -1; |
| } |
| } |
| |
| if (!props.Remove(properties::ref)) { |
| KLOG_ERROR(TAG, "Failed to remove key ref\n"); |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| int e4crypt_install_keyring() |
| { |
| device_keyring = add_key("keyring", |
| "e4crypt", |
| 0, |
| 0, |
| KEY_SPEC_SESSION_KEYRING); |
| |
| if (device_keyring == -1) { |
| KLOG_ERROR(TAG, "Failed to create keyring\n"); |
| return -1; |
| } |
| |
| KLOG_INFO(TAG, "Keyring created wth id %d in process %d\n", |
| device_keyring, getpid()); |
| |
| // ext4enc:TODO set correct permissions |
| long result = keyctl_setperm(device_keyring, 0x3f3f3f3f); |
| if (result) { |
| KLOG_ERROR(TAG, "KEYCTL_SETPERM failed with error %ld\n", result); |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| int e4crypt_install_key(const char* dir) |
| { |
| UnencryptedProperties props(dir); |
| auto key = props.Get<std::string>(properties::key); |
| |
| // Get password to decrypt as needed |
| if (e4crypt_non_default_key(dir)) { |
| std::string result = vold_command("cryptfs getpw"); |
| // result is either |
| // 200 0 -1 |
| // or |
| // 200 0 {{sensitive}} 0001020304 |
| // where 0001020304 is hex encoding of password |
| std::istringstream i(result); |
| std::string bit; |
| i >> bit; |
| if (bit != "200") { |
| KLOG_ERROR(TAG, "Expecting 200\n"); |
| return -1; |
| } |
| |
| i >> bit; |
| if (bit != arbitrary_sequence_number) { |
| KLOG_ERROR(TAG, "Expecting %s\n", arbitrary_sequence_number.c_str()); |
| return -1; |
| } |
| |
| i >> bit; |
| if (bit != "{{sensitive}}") { |
| KLOG_INFO(TAG, "Not encrypted\n"); |
| return -1; |
| } |
| |
| i >> bit; |
| } |
| |
| // Add key to keyring |
| ext4_encryption_key ext4_key = {0, {0}, 0}; |
| if (key.length() > sizeof(ext4_key.raw)) { |
| KLOG_ERROR(TAG, "Key too long\n"); |
| return -1; |
| } |
| |
| ext4_key.mode = 0; |
| memcpy(ext4_key.raw, &key[0], key.length()); |
| ext4_key.size = key.length(); |
| |
| // ext4enc:TODO Use better reference not 1234567890 |
| key_serial_t key_id = add_key("logon", "ext4-key:1234567890", |
| (void*)&ext4_key, sizeof(ext4_key), |
| device_keyring); |
| |
| if (key_id == -1) { |
| KLOG_ERROR(TAG, "Failed to insert key into keyring with error %s\n", |
| strerror(errno)); |
| return -1; |
| } |
| |
| KLOG_INFO(TAG, "Added key %d to keyring %d in process %d\n", |
| key_id, device_keyring, getpid()); |
| |
| // ext4enc:TODO set correct permissions |
| long result = keyctl_setperm(key_id, 0x3f3f3f3f); |
| if (result) { |
| KLOG_ERROR(TAG, "KEYCTL_SETPERM failed with error %ld\n", result); |
| return -1; |
| } |
| |
| // Save reference to key so we can set policy later |
| if (!props.Set(properties::ref, "ext4-key:1234567890")) { |
| KLOG_ERROR(TAG, "Cannot save key reference\n"); |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| int e4crypt_set_directory_policy(const char* dir) |
| { |
| // Only set policy on first level /data directories |
| // To make this less restrictive, consider using a policy file. |
| // However this is overkill for as long as the policy is simply |
| // to apply a global policy to all /data folders created via makedir |
| if (!dir || strncmp(dir, "/data/", 6) || strchr(dir + 6, '/')) { |
| return 0; |
| } |
| |
| UnencryptedProperties props("/data"); |
| std::string ref = props.Get<std::string>(properties::ref); |
| std::string policy = keyring + "." + ref; |
| KLOG_INFO(TAG, "Setting policy %s\n", policy.c_str()); |
| int result = do_policy_set(dir, policy.c_str()); |
| if (result) { |
| KLOG_ERROR(TAG, "Setting policy on %s failed!\n", dir); |
| return -1; |
| } |
| |
| return 0; |
| } |