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v261
src/shared/cryptsetup-tpm2.c
357 строк
14 KB
Lennart Poettering
cryptsetup: handle DA lockout/bad PIN properly
19 июн 2025, 13:33
19 июн 2025, 13:33
df21cec
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/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include "sd-json.h" #include "alloc-util.h" #include "ask-password-api.h" #include "cryptsetup-tpm2.h" #include "cryptsetup-util.h" #include "env-util.h" #include "fileio.h" #include "hexdecoct.h" #include "log.h" #include "random-util.h" #include "strv.h" #include "tpm2-util.h" #if HAVE_LIBCRYPTSETUP && HAVE_TPM2 static int get_pin( usec_t until, const char *askpw_credential, AskPasswordFlags askpw_flags, char **ret_pin_str) { _cleanup_(erase_and_freep) char *pin_str = NULL; _cleanup_strv_free_erase_ char **pin = NULL; int r; assert(ret_pin_str); r = getenv_steal_erase("PIN", &pin_str); if (r < 0) return log_error_errno(r, "Failed to acquire PIN from environment: %m"); if (!r) { 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."); AskPasswordRequest req = { .tty_fd = -EBADF, .message = "Please enter TPM2 PIN:", .icon = "drive-harddisk", .keyring = "tpm2-pin", .credential = askpw_credential, .until = until, .hup_fd = -EBADF, }; pin = strv_free_erase(pin); r = ask_password_auto(&req, askpw_flags, &pin); if (r < 0) return log_error_errno(r, "Failed to ask for user pin: %m"); assert(strv_length(pin) == 1); pin_str = strdup(pin[0]); if (!pin_str) return log_oom(); } *ret_pin_str = TAKE_PTR(pin_str); return r; } #endif int acquire_tpm2_key( const char *volume_name, const char *device, uint32_t hash_pcr_mask, uint16_t pcr_bank, const struct iovec *pubkey, uint32_t pubkey_pcr_mask, const char *signature_path, const char *pcrlock_path, uint16_t primary_alg, const char *key_file, size_t key_file_size, uint64_t key_file_offset, const struct iovec blobs[], size_t n_blobs, const struct iovec policy_hash[], size_t n_policy_hash, const struct iovec *salt, const struct iovec *srk, const struct iovec *pcrlock_nv, TPM2Flags flags, usec_t until, const char *askpw_credential, AskPasswordFlags askpw_flags, struct iovec *ret_decrypted_key) { #if HAVE_LIBCRYPTSETUP && HAVE_TPM2 _cleanup_(sd_json_variant_unrefp) sd_json_variant *signature_json = NULL; _cleanup_(iovec_done) struct iovec loaded_blob = {}; _cleanup_free_ char *auto_device = NULL; int r; assert(iovec_is_valid(salt)); if (!device) { r = tpm2_find_device_auto(&auto_device); if (r == -ENODEV) return -EAGAIN; /* Tell the caller to wait for a TPM2 device to show up */ if (r < 0) return log_error_errno(r, "Could not find TPM2 device: %m"); device = auto_device; } if (n_blobs == 0) { _cleanup_free_ char *bindname = NULL; /* If we read the salt via AF_UNIX, make this client recognizable */ if (asprintf(&bindname, "@%" PRIx64"/cryptsetup-tpm2/%s", random_u64(), volume_name) < 0) return log_oom(); r = read_full_file_full( AT_FDCWD, key_file, key_file_offset == 0 ? UINT64_MAX : key_file_offset, key_file_size == 0 ? SIZE_MAX : key_file_size, READ_FULL_FILE_CONNECT_SOCKET, bindname, (char**) &loaded_blob.iov_base, &loaded_blob.iov_len); if (r < 0) return r; blobs = &loaded_blob; n_blobs = 1; } if (pubkey_pcr_mask != 0) { r = tpm2_load_pcr_signature(signature_path, &signature_json); if (r < 0) return log_error_errno(r, "Failed to load pcr signature: %m"); } _cleanup_(tpm2_pcrlock_policy_done) Tpm2PCRLockPolicy pcrlock_policy = {}; if (FLAGS_SET(flags, TPM2_FLAGS_USE_PCRLOCK)) { r = tpm2_pcrlock_policy_load(pcrlock_path, &pcrlock_policy); if (r < 0) return r; if (r == 0) { /* Not found? Then search among passed credentials */ r = tpm2_pcrlock_policy_from_credentials(srk, pcrlock_nv, &pcrlock_policy); if (r < 0) return r; if (r == 0) return log_error_errno(SYNTHETIC_ERRNO(EREMOTE), "Couldn't find pcrlock policy for volume."); } } _cleanup_(tpm2_context_unrefp) Tpm2Context *tpm2_context = NULL; r = tpm2_context_new_or_warn(device, &tpm2_context); if (r < 0) return r; if (!(flags & TPM2_FLAGS_USE_PIN)) { r = tpm2_unseal(tpm2_context, hash_pcr_mask, pcr_bank, pubkey, pubkey_pcr_mask, signature_json, /* pin= */ NULL, FLAGS_SET(flags, TPM2_FLAGS_USE_PCRLOCK) ? &pcrlock_policy : NULL, primary_alg, blobs, n_blobs, policy_hash, n_policy_hash, srk, ret_decrypted_key); if (r == -EREMOTE) return log_error_errno(r, "TPM key integrity check failed. Key enrolled in superblock most likely does not belong to this TPM."); if (ERRNO_IS_NEG_TPM2_UNSEAL_BAD_PCR(r)) return log_error_errno(r, "TPM policy does not match current system state. Either system has been tempered with or policy out-of-date: %m"); if (r < 0) return log_error_errno(r, "Failed to unseal secret using TPM2: %m"); return r; } for (int i = 5;; i--) { _cleanup_(erase_and_freep) char *pin_str = NULL, *b64_salted_pin = NULL; if (i <= 0) return -EACCES; r = get_pin(until, askpw_credential, askpw_flags, &pin_str); if (r < 0) return r; askpw_flags &= ~ASK_PASSWORD_ACCEPT_CACHED; if (iovec_is_set(salt)) { uint8_t salted_pin[SHA256_DIGEST_SIZE] = {}; CLEANUP_ERASE(salted_pin); r = tpm2_util_pbkdf2_hmac_sha256(pin_str, strlen(pin_str), salt->iov_base, salt->iov_len, salted_pin); if (r < 0) return log_error_errno(r, "Failed to perform PBKDF2: %m"); r = base64mem(salted_pin, sizeof(salted_pin), &b64_salted_pin); if (r < 0) return log_error_errno(r, "Failed to base64 encode salted pin: %m"); } else /* no salting needed, backwards compat with non-salted pins */ b64_salted_pin = TAKE_PTR(pin_str); r = tpm2_unseal(tpm2_context, hash_pcr_mask, pcr_bank, pubkey, pubkey_pcr_mask, signature_json, b64_salted_pin, FLAGS_SET(flags, TPM2_FLAGS_USE_PCRLOCK) ? &pcrlock_policy : NULL, primary_alg, blobs, n_blobs, policy_hash, n_policy_hash, srk, ret_decrypted_key); if (r == -EREMOTE) return log_error_errno(r, "TPM key integrity check failed. Key enrolled in superblock most likely does not belong to this TPM."); if (ERRNO_IS_NEG_TPM2_UNSEAL_BAD_PCR(r)) return log_error_errno(r, "TPM policy does not match current system state. Either system has been tempered with or policy out-of-date: %m"); if (r == -ENOLCK) return log_error_errno(r, "TPM is in dictionary attack lock-out mode."); if (r == -EILSEQ) { log_warning_errno(r, "Bad PIN."); continue; } if (r < 0) return log_error_errno(r, "Failed to unseal secret using TPM2: %m"); return r; } #else return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "TPM2 support not available."); #endif } int find_tpm2_auto_data( struct crypt_device *cd, uint32_t search_pcr_mask, int start_token, uint32_t *ret_hash_pcr_mask, uint16_t *ret_pcr_bank, struct iovec *ret_pubkey, uint32_t *ret_pubkey_pcr_mask, uint16_t *ret_primary_alg, struct iovec **ret_blobs, size_t *ret_n_blobs, struct iovec **ret_policy_hash, size_t *ret_n_policy_hash, struct iovec *ret_salt, struct iovec *ret_srk, struct iovec *ret_pcrlock_nv, TPM2Flags *ret_flags, int *ret_keyslot, int *ret_token) { #if HAVE_LIBCRYPTSETUP && HAVE_TPM2 int r, token; assert(cd); assert(ret_hash_pcr_mask); assert(ret_pcrlock_nv); assert(ret_pubkey); assert(ret_pubkey_pcr_mask); assert(ret_primary_alg); assert(ret_blobs); assert(ret_n_blobs); assert(ret_policy_hash); assert(ret_n_policy_hash); assert(ret_salt); assert(ret_srk); assert(ret_pcrlock_nv); assert(ret_flags); assert(ret_keyslot); assert(ret_token); for (token = start_token; token < sym_crypt_token_max(CRYPT_LUKS2); token++) { _cleanup_(iovec_done) struct iovec pubkey = {}, salt = {}, srk = {}, pcrlock_nv = {}; _cleanup_(sd_json_variant_unrefp) sd_json_variant *v = NULL; 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 flags; int keyslot; CLEANUP_ARRAY(blobs, n_blobs, iovec_array_free); CLEANUP_ARRAY(policy_hash, n_policy_hash, iovec_array_free); 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"); r = tpm2_parse_luks2_json( v, &keyslot, &hash_pcr_mask, &pcr_bank, &pubkey, &pubkey_pcr_mask, &primary_alg, &blobs, &n_blobs, &policy_hash, &n_policy_hash, &salt, &srk, &pcrlock_nv, &flags); if (r == -EUCLEAN) /* Gracefully handle issues in JSON fields not owned by us */ continue; if (r < 0) return log_error_errno(r, "Failed to parse TPM2 JSON data: %m"); if (search_pcr_mask == UINT32_MAX || search_pcr_mask == hash_pcr_mask) { if (start_token <= 0) log_info("Automatically discovered security TPM2 token unlocks volume."); *ret_hash_pcr_mask = hash_pcr_mask; *ret_pcr_bank = pcr_bank; *ret_pubkey = TAKE_STRUCT(pubkey); *ret_pubkey_pcr_mask = pubkey_pcr_mask; *ret_primary_alg = primary_alg; *ret_blobs = TAKE_PTR(blobs); *ret_n_blobs = n_blobs; *ret_policy_hash = TAKE_PTR(policy_hash); *ret_n_policy_hash = n_policy_hash; *ret_salt = TAKE_STRUCT(salt); *ret_keyslot = keyslot; *ret_token = token; *ret_srk = TAKE_STRUCT(srk); *ret_pcrlock_nv = TAKE_STRUCT(pcrlock_nv); *ret_flags = flags; return 0; } /* PCR mask doesn't match what is configured, ignore this entry, let's see next */ } return log_error_errno(SYNTHETIC_ERRNO(ENXIO), "No valid TPM2 token data found."); #else return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "TPM2 support not available."); #endif }