/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include "sd-json.h" #include "alloc-util.h" #include "ask-password-api.h" #include "cryptenroll-tpm2.h" #include "cryptsetup-tpm2.h" #include "env-util.h" #include "errno-util.h" #include "fileio.h" #include "hexdecoct.h" #include "json-util.h" #include "log.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 struct iovec policy_hash[], size_t n_policy_hash) { int r; assert(cd); /* Searches among the already enrolled TPM2 tokens for one that matches the exact set of policies specified */ if (n_policy_hash == 0) return -ENOENT; for (int token = 0; token < sym_crypt_token_max(CRYPT_LUKS2); token++) { _cleanup_(sd_json_variant_unrefp) sd_json_variant *v = NULL; int keyslot; sd_json_variant *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 = sd_json_variant_by_key(v, "tpm2-policy-hash"); if (!w) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "TPM2 token data lacks 'tpm2-policy-hash' field."); /* This is either an array of strings (for sharded enrollments), or a single string */ if (sd_json_variant_is_array(w)) { if (sd_json_variant_elements(w) == n_policy_hash) { sd_json_variant *i; bool match = true; size_t j = 0; JSON_VARIANT_ARRAY_FOREACH(i, w) { _cleanup_(iovec_done) struct iovec thash = {}; r = sd_json_variant_unhex(i, &thash.iov_base, &thash.iov_len); if (r < 0) return log_error_errno(r, "Invalid hex data in 'tpm2-policy-hash' field item : %m"); if (iovec_memcmp(policy_hash + j, &thash) != 0) { match = false; break; } j++; } if (match) /* Found entry with the exact same set of hashes */ return keyslot; } } else if (n_policy_hash == 1) { _cleanup_(iovec_done) struct iovec thash = {}; r = sd_json_variant_unhex(w, &thash.iov_base, &thash.iov_len); if (r < 0) return log_error_errno(r, "Invalid hex data in 'tpm2-policy-hash' field: %m"); if (iovec_memcmp(policy_hash + 0, &thash) == 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."); AskPasswordRequest req = { .message = "Please enter TPM2 PIN:", .icon = "drive-harddisk", .keyring = "tpm2-pin", .credential = "cryptenroll.new-tpm2-pin", }; pin = strv_free_erase(pin); r = ask_password_auto( &req, /* until= */ USEC_INFINITY, /* flags= */ 0, &pin); if (r < 0) return log_error_errno(r, "Failed to ask for user pin: %m"); assert(strv_length(pin) == 1); req.message = "Please enter TPM2 PIN (repeat):"; r = ask_password_auto( &req, USEC_INFINITY, /* flags= */ 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 load_volume_key_tpm2( struct crypt_device *cd, const char *cd_node, const char *device, void *ret_vk, size_t *ret_vks) { _cleanup_(iovec_done_erase) struct iovec decrypted_key = {}; _cleanup_(erase_and_freep) char *passphrase = NULL; ssize_t passphrase_size; int r; assert_se(cd); assert_se(cd_node); assert_se(ret_vk); assert_se(ret_vks); bool found_some = false; int token = 0; /* first token to look at */ for (;;) { _cleanup_(iovec_done) struct iovec pubkey = {}, salt = {}, srk = {}, pcrlock_nv = {}; struct iovec *blobs = NULL, *policy_hash = NULL; size_t n_blobs = 0, n_policy_hash = 0; uint32_t hash_pcr_mask, pubkey_pcr_mask; uint16_t pcr_bank, primary_alg; TPM2Flags tpm2_flags; int keyslot; CLEANUP_ARRAY(policy_hash, n_policy_hash, iovec_array_free); CLEANUP_ARRAY(blobs, n_blobs, iovec_array_free); r = find_tpm2_auto_data( cd, UINT32_MAX, token, &hash_pcr_mask, &pcr_bank, &pubkey, &pubkey_pcr_mask, &primary_alg, &blobs, &n_blobs, &policy_hash, &n_policy_hash, &salt, &srk, &pcrlock_nv, &tpm2_flags, &keyslot, &token); if (r == -ENXIO) return log_full_errno(LOG_NOTICE, SYNTHETIC_ERRNO(EAGAIN), found_some ? "No TPM2 metadata matching the current system state found in LUKS2 header." : "No TPM2 metadata enrolled in LUKS2 header."); if (ERRNO_IS_NEG_NOT_SUPPORTED(r)) /* TPM2 support not compiled in? */ return log_debug_errno(SYNTHETIC_ERRNO(EAGAIN), "TPM2 support not available."); if (r < 0) return r; found_some = true; r = acquire_tpm2_key( cd_node, device, hash_pcr_mask, pcr_bank, &pubkey, pubkey_pcr_mask, /* signature_path= */ NULL, /* pcrlock_path= */ NULL, primary_alg, /* key_file= */ NULL, /* key_file_size= */ 0, /* key_file_offset= */ 0, /* no key file */ blobs, n_blobs, policy_hash, n_policy_hash, &salt, &srk, &pcrlock_nv, tpm2_flags, /* until= */ 0, "cryptenroll.tpm2-pin", /* askpw_flags= */ 0, &decrypted_key); if (IN_SET(r, -EACCES, -ENOLCK)) return log_notice_errno(SYNTHETIC_ERRNO(EAGAIN), "TPM2 PIN unlock failed"); if (r != -EPERM) break; token++; /* try a different token next time */ } if (r < 0) return log_error_errno(r, "Unlocking via TPM2 device failed: %m"); passphrase_size = base64mem(decrypted_key.iov_base, decrypted_key.iov_len, &passphrase); if (passphrase_size < 0) return log_oom(); r = crypt_volume_key_get( cd, CRYPT_ANY_SLOT, ret_vk, ret_vks, passphrase, passphrase_size); if (r < 0) return log_error_errno(r, "Unlocking via TPM2 device failed: %m"); return r; } int enroll_tpm2(struct crypt_device *cd, const struct iovec *volume_key, const char *device, uint32_t seal_key_handle, const char *device_key, Tpm2PCRValue *hash_pcr_values, size_t n_hash_pcr_values, const char *pcr_pubkey_path, bool load_pcr_pubkey, uint32_t pubkey_pcr_mask, const char *signature_path, bool use_pin, const char *pcrlock_path, int *ret_slot_to_wipe) { _cleanup_(sd_json_variant_unrefp) sd_json_variant *v = NULL, *signature_json = NULL; _cleanup_(erase_and_freep) char *base64_encoded = NULL; _cleanup_(iovec_done) struct iovec srk = {}, pubkey = {}; _cleanup_(iovec_done_erase) struct iovec secret = {}; const char *node; _cleanup_(erase_and_freep) char *pin_str = NULL; ssize_t base64_encoded_size; int r, keyslot, slot_to_wipe = -1; 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(iovec_is_set(volume_key)); assert(tpm2_pcr_values_valid(hash_pcr_values, n_hash_pcr_values)); assert(TPM2_PCR_MASK_VALID(pubkey_pcr_mask)); assert(ret_slot_to_wipe); 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 = {}; if (pcr_pubkey_path || load_pcr_pubkey) { r = tpm2_load_pcr_public_key(pcr_pubkey_path, &pubkey.iov_base, &pubkey.iov_len); if (r < 0) { if (pcr_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.iov_base, pubkey.iov_len, &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_error_errno(r, "Failed to read TPM PCR signature: %m"); } } } else pubkey_pcr_mask = 0; 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; if (r == 0) return log_error_errno(SYNTHETIC_ERRNO(ENOENT), "Couldn't find pcrlock policy %s.", pcrlock_path); 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."); /* If we use a literal PCR value policy, derive the bank to use from the algorithm specified on the hash values */ 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"); } else if (pubkey_pcr_mask != 0 && !device_key) { /* If no literal PCR value policy is used, then let's determine the mask to use automatically * from the measurements of the TPM. */ r = tpm2_get_best_pcr_bank( tpm2_context, pubkey_pcr_mask, &hash_pcr_bank); if (r < 0) return log_error_errno(r, "Failed to determine best PCR bank: %m"); } /* Unfortunately TPM2 policy semantics make it very hard to combine PolicyAuthorize (which we need * for signed PCR policies) and PolicyAuthorizeNV (which we need for pcrlock policies). Hence, let's * use a "sharded" secret, and lock the first shard to the signed PCR policy, and the 2nd to the * pcrlock – if both are requested. */ TPM2B_DIGEST policy_hash[2] = { TPM2B_DIGEST_MAKE(NULL, TPM2_SHA256_DIGEST_SIZE), TPM2B_DIGEST_MAKE(NULL, TPM2_SHA256_DIGEST_SIZE), }; size_t n_policy_hash = 1; /* If both PCR public key unlock and pcrlock unlock is selected, then we create the one for PCR public key unlock first. */ r = tpm2_calculate_sealing_policy( hash_pcr_values, n_hash_pcr_values, iovec_is_set(&pubkey) ? &public : NULL, use_pin, pcrlock_path && !iovec_is_set(&pubkey) ? &pcrlock_policy : NULL, policy_hash + 0); if (r < 0) return r; if (pcrlock_path && iovec_is_set(&pubkey)) { r = tpm2_calculate_sealing_policy( hash_pcr_values, n_hash_pcr_values, /* public= */ NULL, /* This one is off now */ use_pin, &pcrlock_policy, /* And this one on instead. */ policy_hash + 1); if (r < 0) return r; n_policy_hash ++; } struct iovec *blobs = NULL; size_t n_blobs = 0; CLEANUP_ARRAY(blobs, n_blobs, iovec_array_free); if (device_key) { if (n_policy_hash > 1) return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "Combined signed PCR policies and pcrlock policies cannot be calculated offline, currently."); blobs = new0(struct iovec, 1); if (!blobs) return log_oom(); n_blobs = 1; r = tpm2_calculate_seal( seal_key_handle, &device_key_public, /* attributes= */ NULL, /* secret= */ NULL, policy_hash + 0, pin_str, &secret, blobs + 0, &srk); } else r = tpm2_seal(tpm2_context, seal_key_handle, policy_hash, n_policy_hash, pin_str, &secret, &blobs, &n_blobs, /* ret_primary_alg= */ NULL, &srk); if (r < 0) return log_error_errno(r, "Failed to seal to TPM2: %m"); struct iovec policy_hash_as_iovec[2] = { IOVEC_MAKE(policy_hash[0].buffer, policy_hash[0].size), IOVEC_MAKE(policy_hash[1].buffer, policy_hash[1].size), }; /* Let's see if we already have this specific PCR policy hash enrolled, if so, exit early. */ r = search_policy_hash(cd, policy_hash_as_iovec, n_policy_hash); if (r == -ENOENT) log_debug_errno(r, "PCR policy hash not yet enrolled, enrolling now."); else if (r < 0) return r; else if (use_pin) { log_debug("This PCR set is already enrolled, re-enrolling anyway to update PIN."); slot_to_wipe = r; } else { log_info("This PCR set is already enrolled, executing no operation."); *ret_slot_to_wipe = -1; return r; /* return existing keyslot, so that wiping won't kill it */ } /* If possible, verify the sealed data object. */ if ((!iovec_is_set(&pubkey) || signature_json) && !any_pcr_value_specified && !device_key) { _cleanup_(iovec_done_erase) struct iovec secret2 = {}; log_debug("Unsealing for verification..."); r = tpm2_unseal(tpm2_context, hash_pcr_mask, hash_pcr_bank, &pubkey, pubkey_pcr_mask, signature_json, pin_str, pcrlock_path ? &pcrlock_policy : NULL, /* primary_alg= */ 0, blobs, n_blobs, policy_hash_as_iovec, n_policy_hash, &srk, &secret2); if (r < 0) return log_error_errno(r, "Failed to unseal secret using TPM2: %m"); if (iovec_memcmp(&secret, &secret2) != 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.iov_base, secret.iov_len, &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->iov_base, volume_key->iov_len, 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_pcr_mask, /* primary_alg= */ 0, blobs, n_blobs, policy_hash_as_iovec, n_policy_hash, use_pin ? &IOVEC_MAKE(binary_salt, sizeof(binary_salt)) : NULL, &srk, pcrlock_path ? &pcrlock_policy.nv_handle : NULL, 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); *ret_slot_to_wipe = slot_to_wipe; return keyslot; }