| /* 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_free_ char *pin_str = NULL; |
| int r; |
| TPM2Flags flags = 0; |
| |
| 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 hash_pcr_mask, |
| const char *pubkey_path, |
| uint32_t pubkey_pcr_mask, |
| const char *signature_path, |
| bool use_pin) { |
| |
| _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; |
| size_t secret_size, blob_size, hash_size, pubkey_size = 0; |
| _cleanup_free_ void *blob = NULL, *hash = NULL, *pubkey = NULL; |
| uint16_t pcr_bank, primary_alg; |
| 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_MASK_VALID(hash_pcr_mask)); |
| 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"); |
| } |
| |
| 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 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 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"); |
| } |
| |
| r = tpm2_seal(device, |
| hash_pcr_mask, |
| pubkey, pubkey_size, |
| pubkey_pcr_mask, |
| pin_str, |
| &secret, &secret_size, |
| &blob, &blob_size, |
| &hash, &hash_size, |
| &pcr_bank, |
| &primary_alg); |
| if (r < 0) |
| return r; |
| |
| /* Let's see if we already have this specific PCR policy hash enrolled, if so, exit early. */ |
| r = search_policy_hash(cd, hash, hash_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 */ |
| } |
| |
| /* Quick verification that everything is in order, we are not in a hurry after all. */ |
| if (!pubkey || signature_json) { |
| _cleanup_(erase_and_freep) void *secret2 = NULL; |
| size_t secret2_size; |
| |
| log_debug("Unsealing for verification..."); |
| r = tpm2_unseal(device, |
| hash_pcr_mask, |
| pcr_bank, |
| pubkey, pubkey_size, |
| pubkey_pcr_mask, |
| signature_json, |
| pin_str, |
| primary_alg, |
| blob, blob_size, |
| hash, hash_size, |
| &secret2, &secret2_size); |
| if (r < 0) |
| return r; |
| |
| 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, |
| pcr_bank, |
| pubkey, pubkey_size, |
| pubkey_pcr_mask, |
| primary_alg, |
| blob, blob_size, |
| hash, hash_size, |
| use_pin ? binary_salt : NULL, |
| use_pin ? sizeof(binary_salt) : 0, |
| 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; |
| } |
