/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include "sd-json.h" #include "ask-password-api.h" #include "cryptsetup-fido2.h" #include "env-util.h" #include "fido2-util.h" #include "fileio.h" #include "hexdecoct.h" #include "iovec-util.h" #include "libfido2-util.h" #include "parse-util.h" #include "random-util.h" #include "strv.h" int acquire_fido2_key( const char *volume_name, const char *friendly_name, const char *device, const char *rp_id, const void *cid, size_t cid_size, const char *key_file, size_t key_file_size, uint64_t key_file_offset, const struct iovec *key_data, usec_t until, Fido2EnrollFlags required, const char *askpw_credential, AskPasswordFlags askpw_flags, void **ret_decrypted_key, size_t *ret_decrypted_key_size) { _cleanup_(erase_and_freep) char *envpw = NULL; _cleanup_strv_free_erase_ char **pins = NULL; _cleanup_(iovec_done_erase) struct iovec loaded_salt = {}; bool device_exists = false; struct iovec salt; int r; if ((required & (FIDO2ENROLL_PIN | FIDO2ENROLL_UP | FIDO2ENROLL_UV)) && FLAGS_SET(askpw_flags, ASK_PASSWORD_HEADLESS)) return log_error_errno(SYNTHETIC_ERRNO(ENOPKG), "Local verification is required to unlock this volume, but the 'headless' parameter was set."); assert(cid); assert(key_file || iovec_is_set(key_data)); if (iovec_is_set(key_data)) salt = *key_data; else { if (key_file_size > 0) log_debug("Ignoring 'keyfile-size=' option for a FIDO2 salt file."); r = fido2_read_salt_file( key_file, key_file_offset, /* client= */ "cryptsetup", /* node= */ volume_name, &loaded_salt); if (r < 0) return r; salt = loaded_salt; } r = getenv_steal_erase("PIN", &envpw); if (r < 0) return log_error_errno(r, "Failed to acquire password from environment: %m"); if (r > 0) { pins = strv_new(envpw); if (!pins) return log_oom(); } for (;;) { if (!device_exists) { /* Before we inquire for the PIN we'll need, if we never talked to the device, check * if the device actually is plugged in. Otherwise we'll ask for the PIN already when * the device is not plugged in, which is confusing. */ r = fido2_have_device(device); if (r < 0) return r; if (r == 0) /* no device found, return EAGAIN so that caller will wait/watch udev */ return -EAGAIN; device_exists = true; /* now we know for sure, a device exists, no need to ask again */ } /* Always make an attempt before asking for PIN. * fido2_use_hmac_hash() will perform a pre-flight check for whether the credential for * can be found on one of the connected devices. This way, we can avoid prompting the user * for a PIN when we are sure that no device can be used. */ r = fido2_use_hmac_hash( device, rp_id ?: "io.systemd.cryptsetup", salt.iov_base, salt.iov_len, cid, cid_size, pins, required, ret_decrypted_key, ret_decrypted_key_size); if (!IN_SET(r, -ENOANO, /* needs pin */ -ENOLCK)) /* pin incorrect */ return r; device_exists = true; /* that a PIN is needed/wasn't correct means that we managed to * talk to a device */ if (FLAGS_SET(askpw_flags, ASK_PASSWORD_HEADLESS)) return log_error_errno(SYNTHETIC_ERRNO(ENOPKG), "PIN querying disabled via 'headless' option. Use the '$PIN' environment variable."); static const AskPasswordRequest req = { .message = "Please enter security token PIN:", .icon = "drive-harddisk", .keyring = "fido2-pin", .credential = "cryptsetup.fido2-pin", }; pins = strv_free_erase(pins); r = ask_password_auto(&req, until, askpw_flags, &pins); if (r < 0) return log_error_errno(r, "Failed to ask for user password: %m"); askpw_flags &= ~ASK_PASSWORD_ACCEPT_CACHED; } } int acquire_fido2_key_auto( struct crypt_device *cd, const char *name, const char *friendly_name, const char *fido2_device, usec_t until, const char *askpw_credential, AskPasswordFlags askpw_flags, void **ret_decrypted_key, size_t *ret_decrypted_key_size) { _cleanup_free_ void *cid = NULL; size_t cid_size = 0; int r, ret = -ENOENT; Fido2EnrollFlags required = 0; assert(cd); assert(name); assert(ret_decrypted_key); assert(ret_decrypted_key_size); /* Loads FIDO2 metadata from LUKS2 JSON token headers. */ for (int token = 0; token < sym_crypt_token_max(CRYPT_LUKS2); token++) { _cleanup_(sd_json_variant_unrefp) sd_json_variant *v = NULL; sd_json_variant *w; _cleanup_free_ void *salt = NULL; _cleanup_free_ char *rp = NULL; size_t salt_size = 0; int ks; r = cryptsetup_get_token_as_json(cd, token, "systemd-fido2", &v); if (IN_SET(r, -ENOENT, -EINVAL, -EMEDIUMTYPE)) continue; if (r < 0) return log_error_errno(r, "Failed to read JSON token data off disk: %m"); ks = cryptsetup_get_keyslot_from_token(v); if (ks < 0) { /* Handle parsing errors of the keyslots field gracefully, since it's not 'owned' by * us, but by the LUKS2 spec */ log_warning_errno(ks, "Failed to extract keyslot index from FIDO2 JSON data token %i, skipping: %m", token); continue; } w = sd_json_variant_by_key(v, "fido2-credential"); if (!w) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "FIDO2 token data lacks 'fido2-credential' field."); r = sd_json_variant_unbase64(w, &cid, &cid_size); if (r < 0) return log_error_errno(r, "Invalid base64 data in 'fido2-credential' field: %m"); w = sd_json_variant_by_key(v, "fido2-salt"); if (!w) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "FIDO2 token data lacks 'fido2-salt' field."); assert(!salt); assert(salt_size == 0); r = sd_json_variant_unbase64(w, &salt, &salt_size); if (r < 0) return log_error_errno(r, "Failed to decode base64 encoded salt: %m"); w = sd_json_variant_by_key(v, "fido2-rp"); if (w) { /* The "rp" field is optional. */ if (!sd_json_variant_is_string(w)) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "FIDO2 token data's 'fido2-rp' field is not a string."); assert(!rp); rp = strdup(sd_json_variant_string(w)); if (!rp) return log_oom(); } w = sd_json_variant_by_key(v, "fido2-clientPin-required"); if (w) { /* The "fido2-clientPin-required" field is optional. */ if (!sd_json_variant_is_boolean(w)) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "FIDO2 token data's 'fido2-clientPin-required' field is not a boolean."); SET_FLAG(required, FIDO2ENROLL_PIN, sd_json_variant_boolean(w)); } else required |= FIDO2ENROLL_PIN_IF_NEEDED; /* compat with 248, where the field was unset */ w = sd_json_variant_by_key(v, "fido2-up-required"); if (w) { /* The "fido2-up-required" field is optional. */ if (!sd_json_variant_is_boolean(w)) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "FIDO2 token data's 'fido2-up-required' field is not a boolean."); SET_FLAG(required, FIDO2ENROLL_UP, sd_json_variant_boolean(w)); } else required |= FIDO2ENROLL_UP_IF_NEEDED; /* compat with 248 */ w = sd_json_variant_by_key(v, "fido2-uv-required"); if (w) { /* The "fido2-uv-required" field is optional. */ if (!sd_json_variant_is_boolean(w)) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "FIDO2 token data's 'fido2-uv-required' field is not a boolean."); SET_FLAG(required, FIDO2ENROLL_UV, sd_json_variant_boolean(w)); } else required |= FIDO2ENROLL_UV_OMIT; /* compat with 248 */ ret = acquire_fido2_key( name, friendly_name, fido2_device, rp, cid, cid_size, /* key_file= */ NULL, /* salt is read from LUKS header instead of key_file */ /* key_file_size= */ 0, /* key_file_offset= */ 0, &IOVEC_MAKE(salt, salt_size), until, required, "cryptsetup.fido2-pin", askpw_flags, ret_decrypted_key, ret_decrypted_key_size); if (ret == 0) break; } if (!cid) return log_error_errno(SYNTHETIC_ERRNO(ENXIO), "No valid FIDO2 token data found."); if (ret == -EAGAIN) /* fido2 device does not exist, or UV is blocked; caller will prompt for retry */ return log_debug_errno(ret, "FIDO2 token does not exist, or UV is blocked."); if (ret < 0) return log_error_errno(ret, "Failed to unlock LUKS volume with FIDO2 token: %m"); log_info("Unlocked volume via automatically discovered security FIDO2 token."); return ret; }