/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include "alloc-util.h" #include "ask-password-api.h" #include "cryptenroll-tpm2.h" #include "env-util.h" #include "fileio.h" #include "hexdecoct.h" #include "json.h" #include "memory-util.h" #include "random-util.h" #include "sha256.h" #include "tpm2-util.h" static int search_policy_hash( struct crypt_device *cd, const void *hash, size_t hash_size) { int r; assert(cd); assert(hash || hash_size == 0); if (hash_size == 0) return 0; for (int token = 0; token < sym_crypt_token_max(CRYPT_LUKS2); token ++) { _cleanup_(json_variant_unrefp) JsonVariant *v = NULL; _cleanup_free_ void *thash = NULL; size_t thash_size = 0; int keyslot; JsonVariant *w; r = cryptsetup_get_token_as_json(cd, token, "systemd-tpm2", &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"); keyslot = cryptsetup_get_keyslot_from_token(v); if (keyslot < 0) { /* Handle parsing errors of the keyslots field gracefully, since it's not 'owned' by * us, but by the LUKS2 spec */ log_warning_errno(keyslot, "Failed to determine keyslot of JSON token %i, skipping: %m", token); continue; } w = json_variant_by_key(v, "tpm2-policy-hash"); if (!w || !json_variant_is_string(w)) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "TPM2 token data lacks 'tpm2-policy-hash' field."); r = unhexmem(json_variant_string(w), SIZE_MAX, &thash, &thash_size); if (r < 0) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Invalid base64 data in 'tpm2-policy-hash' field."); if (memcmp_nn(hash, hash_size, thash, thash_size) == 0) return keyslot; /* Found entry with same hash. */ } return -ENOENT; /* Not found */ } static int get_pin(char **ret_pin_str, TPM2Flags *ret_flags) { _cleanup_(erase_and_freep) char *pin_str = NULL; TPM2Flags flags = 0; int r; assert(ret_pin_str); assert(ret_flags); r = getenv_steal_erase("NEWPIN", &pin_str); if (r < 0) return log_error_errno(r, "Failed to acquire PIN from environment: %m"); if (r > 0) flags |= TPM2_FLAGS_USE_PIN; else { for (size_t i = 5;; i--) { _cleanup_strv_free_erase_ char **pin = NULL, **pin2 = NULL; if (i <= 0) return log_error_errno( SYNTHETIC_ERRNO(ENOKEY), "Too many attempts, giving up."); pin = strv_free_erase(pin); r = ask_password_auto( "Please enter TPM2 PIN:", "drive-harddisk", NULL, "tpm2-pin", "cryptenroll.tpm2-pin", USEC_INFINITY, 0, &pin); if (r < 0) return log_error_errno(r, "Failed to ask for user pin: %m"); assert(strv_length(pin) == 1); r = ask_password_auto( "Please enter TPM2 PIN (repeat):", "drive-harddisk", NULL, "tpm2-pin", "cryptenroll.tpm2-pin", USEC_INFINITY, 0, &pin2); if (r < 0) return log_error_errno(r, "Failed to ask for user pin: %m"); assert(strv_length(pin) == 1); if (strv_equal(pin, pin2)) { pin_str = strdup(*pin); if (!pin_str) return log_oom(); flags |= TPM2_FLAGS_USE_PIN; break; } log_error("PINs didn't match, please try again!"); } } *ret_flags = flags; *ret_pin_str = TAKE_PTR(pin_str); return 0; } int enroll_tpm2(struct crypt_device *cd, const void *volume_key, size_t volume_key_size, const char *device, uint32_t seal_key_handle, const char *device_key, Tpm2PCRValue *hash_pcr_values, size_t n_hash_pcr_values, const char *pubkey_path, uint32_t pubkey_pcr_mask, const char *signature_path, bool use_pin, const char *pcrlock_path) { _cleanup_(erase_and_freep) void *secret = NULL; _cleanup_(json_variant_unrefp) JsonVariant *v = NULL, *signature_json = NULL; _cleanup_(erase_and_freep) char *base64_encoded = NULL; _cleanup_free_ void *srk_buf = NULL; size_t secret_size, blob_size, pubkey_size = 0, srk_buf_size = 0; _cleanup_free_ void *blob = NULL, *pubkey = NULL; const char *node; _cleanup_(erase_and_freep) char *pin_str = NULL; ssize_t base64_encoded_size; int r, keyslot; TPM2Flags flags = 0; uint8_t binary_salt[SHA256_DIGEST_SIZE] = {}; /* * erase the salt, we'd rather attempt to not have this in a coredump * as an attacker would have all the parameters but pin used to create * the session key. This problem goes away when we move to a trusted * primary key, aka the SRK. */ CLEANUP_ERASE(binary_salt); assert(cd); assert(volume_key); assert(volume_key_size > 0); assert(tpm2_pcr_values_valid(hash_pcr_values, n_hash_pcr_values)); assert(TPM2_PCR_MASK_VALID(pubkey_pcr_mask)); assert_se(node = crypt_get_device_name(cd)); if (use_pin) { r = get_pin(&pin_str, &flags); if (r < 0) return r; r = crypto_random_bytes(binary_salt, sizeof(binary_salt)); if (r < 0) return log_error_errno(r, "Failed to acquire random salt: %m"); uint8_t salted_pin[SHA256_DIGEST_SIZE] = {}; CLEANUP_ERASE(salted_pin); r = tpm2_util_pbkdf2_hmac_sha256(pin_str, strlen(pin_str), binary_salt, sizeof(binary_salt), salted_pin); if (r < 0) return log_error_errno(r, "Failed to perform PBKDF2: %m"); pin_str = erase_and_free(pin_str); /* re-stringify pin_str */ base64_encoded_size = base64mem(salted_pin, sizeof(salted_pin), &pin_str); if (base64_encoded_size < 0) return log_error_errno(base64_encoded_size, "Failed to base64 encode salted pin: %m"); } TPM2B_PUBLIC public = {}; r = tpm2_load_pcr_public_key(pubkey_path, &pubkey, &pubkey_size); if (r < 0) { if (pubkey_path || signature_path || r != -ENOENT) return log_error_errno(r, "Failed to read TPM PCR public key: %m"); log_debug_errno(r, "Failed to read TPM2 PCR public key, proceeding without: %m"); pubkey_pcr_mask = 0; } else { r = tpm2_tpm2b_public_from_pem(pubkey, pubkey_size, &public); if (r < 0) return log_error_errno(r, "Could not convert public key to TPM2B_PUBLIC: %m"); if (signature_path) { /* Also try to load the signature JSON object, to verify that our enrollment will work. * This is optional however, skip it if it's not explicitly provided. */ r = tpm2_load_pcr_signature(signature_path, &signature_json); if (r < 0) return log_debug_errno(r, "Failed to read TPM PCR signature: %m"); } } bool any_pcr_value_specified = tpm2_pcr_values_has_any_values(hash_pcr_values, n_hash_pcr_values); _cleanup_(tpm2_pcrlock_policy_done) Tpm2PCRLockPolicy pcrlock_policy = {}; if (pcrlock_path) { r = tpm2_pcrlock_policy_load(pcrlock_path, &pcrlock_policy); if (r < 0) return r; any_pcr_value_specified = true; flags |= TPM2_FLAGS_USE_PCRLOCK; } _cleanup_(tpm2_context_unrefp) Tpm2Context *tpm2_context = NULL; TPM2B_PUBLIC device_key_public = {}; if (device_key) { r = tpm2_load_public_key_file(device_key, &device_key_public); if (r < 0) return r; if (!tpm2_pcr_values_has_all_values(hash_pcr_values, n_hash_pcr_values)) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Must provide all PCR values when using TPM2 device key."); } else { r = tpm2_context_new_or_warn(device, &tpm2_context); if (r < 0) return r; if (!tpm2_pcr_values_has_all_values(hash_pcr_values, n_hash_pcr_values)) { r = tpm2_pcr_read_missing_values(tpm2_context, hash_pcr_values, n_hash_pcr_values); if (r < 0) return log_error_errno(r, "Could not read pcr values: %m"); } } uint16_t hash_pcr_bank = 0; uint32_t hash_pcr_mask = 0; if (n_hash_pcr_values > 0) { size_t hash_count; r = tpm2_pcr_values_hash_count(hash_pcr_values, n_hash_pcr_values, &hash_count); if (r < 0) return log_error_errno(r, "Could not get hash count: %m"); if (hash_count > 1) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Multiple PCR banks selected."); hash_pcr_bank = hash_pcr_values[0].hash; r = tpm2_pcr_values_to_mask(hash_pcr_values, n_hash_pcr_values, hash_pcr_bank, &hash_pcr_mask); if (r < 0) return log_error_errno(r, "Could not get hash mask: %m"); } TPM2B_DIGEST policy = TPM2B_DIGEST_MAKE(NULL, TPM2_SHA256_DIGEST_SIZE); r = tpm2_calculate_sealing_policy( hash_pcr_values, n_hash_pcr_values, pubkey ? &public : NULL, use_pin, pcrlock_path ? &pcrlock_policy : NULL, &policy); if (r < 0) return r; if (device_key) r = tpm2_calculate_seal( seal_key_handle, &device_key_public, /* attributes= */ NULL, /* secret= */ NULL, /* secret_size= */ 0, &policy, pin_str, &secret, &secret_size, &blob, &blob_size, &srk_buf, &srk_buf_size); else r = tpm2_seal(tpm2_context, seal_key_handle, &policy, pin_str, &secret, &secret_size, &blob, &blob_size, /* ret_primary_alg= */ NULL, &srk_buf, &srk_buf_size); if (r < 0) return log_error_errno(r, "Failed to seal to TPM2: %m"); /* Let's see if we already have this specific PCR policy hash enrolled, if so, exit early. */ r = search_policy_hash(cd, policy.buffer, policy.size); if (r == -ENOENT) log_debug_errno(r, "PCR policy hash not yet enrolled, enrolling now."); else if (r < 0) return r; else { log_info("This PCR set is already enrolled, executing no operation."); return r; /* return existing keyslot, so that wiping won't kill it */ } /* If possible, verify the sealed data object. */ if ((!pubkey || signature_json) && !any_pcr_value_specified && !device_key) { _cleanup_(erase_and_freep) void *secret2 = NULL; size_t secret2_size; log_debug("Unsealing for verification..."); r = tpm2_unseal(tpm2_context, hash_pcr_mask, hash_pcr_bank, pubkey, pubkey_size, pubkey_pcr_mask, signature_json, pin_str, pcrlock_path ? &pcrlock_policy : NULL, /* primary_alg= */ 0, blob, blob_size, policy.buffer, policy.size, srk_buf, srk_buf_size, &secret2, &secret2_size); if (r < 0) return log_error_errno(r, "Failed to unseal secret using TPM2: %m"); if (memcmp_nn(secret, secret_size, secret2, secret2_size) != 0) return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "TPM2 seal/unseal verification failed."); } /* let's base64 encode the key to use, for compat with homed (and it's easier to every type it in by keyboard, if that might end up being necessary. */ base64_encoded_size = base64mem(secret, secret_size, &base64_encoded); if (base64_encoded_size < 0) return log_error_errno(base64_encoded_size, "Failed to base64 encode secret key: %m"); r = cryptsetup_set_minimal_pbkdf(cd); if (r < 0) return log_error_errno(r, "Failed to set minimal PBKDF: %m"); keyslot = crypt_keyslot_add_by_volume_key( cd, CRYPT_ANY_SLOT, volume_key, volume_key_size, base64_encoded, base64_encoded_size); if (keyslot < 0) return log_error_errno(keyslot, "Failed to add new TPM2 key to %s: %m", node); r = tpm2_make_luks2_json( keyslot, hash_pcr_mask, hash_pcr_bank, pubkey, pubkey_size, pubkey_pcr_mask, /* primary_alg= */ 0, blob, blob_size, policy.buffer, policy.size, use_pin ? binary_salt : NULL, use_pin ? sizeof(binary_salt) : 0, srk_buf, srk_buf_size, flags, &v); if (r < 0) return log_error_errno(r, "Failed to prepare TPM2 JSON token object: %m"); r = cryptsetup_add_token_json(cd, v); if (r < 0) return log_error_errno(r, "Failed to add TPM2 JSON token to LUKS2 header: %m"); log_info("New TPM2 token enrolled as key slot %i.", keyslot); return keyslot; }