diff --git a/Android.mk b/Android.mk index 4052b7d..94d6ca2 100644 --- a/Android.mk +++ b/Android.mk @@ -43,7 +43,8 @@ common_shared_libraries := \ libselinux \ libutils \ libhardware \ - libsoftkeymaster + libsoftkeymaster \ + libbase common_static_libraries := \ libfs_mgr \ diff --git a/CommandListener.cpp b/CommandListener.cpp index 73a26e4..696e37d 100644 --- a/CommandListener.cpp +++ b/CommandListener.cpp @@ -38,6 +38,7 @@ #include "Process.h" #include "Loop.h" #include "Devmapper.h" +#include "Ext4Crypt.h" #include "cryptfs.h" #include "fstrim.h" @@ -733,6 +734,25 @@ int CommandListener::CryptfsCmd::runCommand(SocketClient *cli, dumpArgs(argc, argv, -1); cryptfs_clear_password(); rc = 0; + } else if (!strcmp(argv[1], "setusercryptopolicies")) { + if (argc != 3) { + cli->sendMsg(ResponseCode::CommandSyntaxError, + "Usage: cryptfs setusercryptopolicies ", false); + return 0; + } + SLOGD("cryptfs setusercryptopolicies"); + dumpArgs(argc, argv, -1); + rc = e4crypt_set_user_crypto_policies(argv[2]); + } else if (!strcmp(argv[1], "createnewuserdir")) { + if (argc != 4) { + cli->sendMsg(ResponseCode::CommandSyntaxError, + "Usage: cryptfs createnewuserdir ", false); + return 0; + } + // ext4enc:TODO: send a CommandSyntaxError if argv[2] not an integer + SLOGD("cryptfs createnewuserdir"); + dumpArgs(argc, argv, -1); + rc = e4crypt_create_new_user_dir(argv[2], argv[3]); } else { dumpArgs(argc, argv, -1); cli->sendMsg(ResponseCode::CommandSyntaxError, "Unknown cryptfs cmd", false); diff --git a/Ext4Crypt.cpp b/Ext4Crypt.cpp index d1e22ec..7470ff9 100644 --- a/Ext4Crypt.cpp +++ b/Ext4Crypt.cpp @@ -7,17 +7,24 @@ #include #include +#include #include +#include +#include +#include #include #include #include "unencrypted_properties.h" #include "key_control.h" #include "cryptfs.h" +#include "ext4_crypt_init_extensions.h" #define LOG_TAG "Ext4Crypt" #include "cutils/log.h" #include +#include +#include namespace { // Key length in bits @@ -69,7 +76,7 @@ namespace { } } -static std::string e4crypt_install_key(const unsigned char *key_bytes); +static std::string e4crypt_install_key(const std::string &key); static int put_crypt_ftr_and_key(const crypt_mnt_ftr& crypt_ftr, UnencryptedProperties& props) @@ -242,10 +249,10 @@ int e4crypt_change_password(const char* path, int crypt_type, return -1; } - const unsigned char* master_key + const unsigned char* master_key_bytes = reinterpret_cast(&mki->second.master_key[0]); - if (cryptfs_set_password(&ftr, password, master_key)) { + if (cryptfs_set_password(&ftr, password, master_key_bytes)) { SLOGE("Failed to set password"); return -1; } @@ -307,8 +314,8 @@ int e4crypt_check_passwd(const char* path, const char* password) return -1; } - unsigned char master_key[key_length / 8]; - if (cryptfs_get_master_key (&ftr, password, master_key)){ + 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)) { @@ -323,12 +330,12 @@ int e4crypt_check_passwd(const char* path, const char* password) SLOGW("Failed to reset failed_decrypt_count"); } } + std::string master_key(reinterpret_cast(master_key_bytes), + sizeof(master_key_bytes)); struct timespec now; clock_gettime(CLOCK_BOOTTIME, &now); - s_key_store[path] = keys{std::string(reinterpret_cast(master_key), - sizeof(master_key)), - password, + s_key_store[path] = keys{master_key, password, now.tv_sec + password_max_age_seconds}; auto raw_ref = e4crypt_install_key(master_key); if (raw_ref.empty()) { @@ -346,7 +353,7 @@ int e4crypt_check_passwd(const char* path, const char* password) // Install password into global keyring // Return raw key reference for use in policy -static std::string e4crypt_install_key(const unsigned char *key_bytes) +static std::string e4crypt_install_key(const std::string &key) { // ext4enc:TODO Currently raw key is required to be of length // sizeof(ext4_key.raw) == EXT4_MAX_KEY_SIZE, so zero pad to @@ -357,7 +364,7 @@ static std::string e4crypt_install_key(const unsigned char *key_bytes) memset(ext4_key.raw, 0, sizeof(ext4_key.raw)); static_assert(key_length / 8 <= sizeof(ext4_key.raw), "Key too long!"); - memcpy(ext4_key.raw, key_bytes, key_length / 8); + memcpy(ext4_key.raw, &key[0], key.size()); // Get raw keyref - used to make keyname and to pass to ioctl auto raw_ref = generate_key_ref(ext4_key.raw, ext4_key.size); @@ -383,7 +390,7 @@ static std::string e4crypt_install_key(const unsigned char *key_bytes) if (key_id == -1) { SLOGE("Failed to insert key into keyring with error %s", strerror(errno)); - return std::string(); + return ""; } SLOGI("Added key %d (%s) to keyring %d in process %d", @@ -485,3 +492,123 @@ int e4crypt_set_field(const char* path, const char* fieldname, return GetPropsOrAltProps(path).GetChild(properties::props) .Set(fieldname, std::string(value)) ? 0 : -1; } + +// ext4enc:TODO this can't be the only place keys are read from /dev/urandom +// we should unite those places. +static std::string e4crypt_get_user_key( + const char *mount_path, + const char *user_handle, + bool create_if_absent) +{ + // ext4enc:TODO get the path properly + auto key_dir = android::base::StringPrintf("%s/misc/vold/user_keys", + mount_path); + if (mkdir(key_dir.c_str(), 0700) < 0 && errno != EEXIST) { + SLOGE("Unable to create %s (%s)", key_dir.c_str(), strerror(errno)); + return ""; + } + auto key_path = key_dir + "/" + user_handle; + std::string content; + if (android::base::ReadFileToString(key_path, &content)) { + if (content.size() != key_length/8) { + SLOGE("Wrong size key %zu in %s", content.size(), key_path.c_str()); + return ""; + } + return content; + } + if (!create_if_absent) { + SLOGE("No key found in %s", key_path.c_str()); + return ""; + } + std::ifstream urandom("/dev/urandom"); + if (!urandom) { + SLOGE("Unable to open /dev/urandom (%s)", strerror(errno)); + return ""; + } + char key_bytes[key_length / 8]; + errno = 0; + urandom.read(key_bytes, sizeof(key_bytes)); + if (!urandom) { + SLOGE("Unable to read key from /dev/urandom (%s)", strerror(errno)); + return ""; + } + std::string user_key(key_bytes, sizeof(key_bytes)); + if (!android::base::WriteStringToFile(user_key, key_path)) { + SLOGE("Unable to write key to %s (%s)", + key_path.c_str(), strerror(errno)); + return ""; + } + return user_key; +} + +static int e4crypt_set_user_policy(const char *mount_path, const char *user_handle, + const char *path, bool create_if_absent) +{ + SLOGD("e4crypt_set_user_policy for %s", user_handle); + auto user_key = e4crypt_get_user_key(mount_path, user_handle, + create_if_absent); + if (user_key.empty()) { + return -1; + } + auto raw_ref = e4crypt_install_key(user_key); + if (raw_ref.empty()) { + return -1; + } + return do_policy_set(path, raw_ref.c_str(), raw_ref.size()); +} + +int e4crypt_create_new_user_dir(const char *user_handle, const char *path) { + SLOGD("e4crypt_create_new_user_dir(\"%s\", \"%s\")", user_handle, path); + if (mkdir(path, S_IRWXU | S_IRWXG | S_IXOTH) < 0) { + return -1; + } + if (chmod(path, S_IRWXU | S_IRWXG | S_IXOTH) < 0) { + return -1; + } + if (e4crypt_crypto_complete(DATA_MNT_POINT) == 0) { + // ext4enc:TODO handle errors from this. + e4crypt_set_user_policy(DATA_MNT_POINT, user_handle, path, true); + } + return 0; +} + +static bool is_numeric(const char *name) { + for (const char *p = name; *p != '\0'; p++) { + if (!isdigit(*p)) + return false; + } + return true; +} + +int e4crypt_set_user_crypto_policies(const char *dir) +{ + if (e4crypt_crypto_complete(DATA_MNT_POINT) != 0) { + return 0; + } + SLOGD("e4crypt_set_user_crypto_policies"); + std::unique_ptr dirp(opendir(dir), closedir); + if (!dirp) { + SLOGE("Unable to read directory %s, error %s\n", + dir, strerror(errno)); + return -1; + } + for (;;) { + struct dirent *result = readdir(dirp.get()); + if (!result) { + // ext4enc:TODO check errno + break; + } + if (result->d_type != DT_DIR || !is_numeric(result->d_name)) { + continue; // skips user 0, which is a symlink + } + auto user_dir = std::string() + dir + "/" + result->d_name; + // ext4enc:TODO don't hardcode /data + if (e4crypt_set_user_policy("/data", result->d_name, + user_dir.c_str(), false)) { + // ext4enc:TODO If this function fails, stop the boot: we must + // deliver on promised encryption. + SLOGE("Unable to set policy on %s\n", user_dir.c_str()); + } + } + return 0; +} diff --git a/Ext4Crypt.h b/Ext4Crypt.h index 53a26a0..c502b62 100644 --- a/Ext4Crypt.h +++ b/Ext4Crypt.h @@ -18,5 +18,7 @@ int e4crypt_get_field(const char* path, const char* fieldname, char* value, size_t len); int e4crypt_set_field(const char* path, const char* fieldname, const char* value); +int e4crypt_set_user_crypto_policies(const char *path); +int e4crypt_create_new_user_dir(const char *user_handle, const char *path); __END_DECLS