diff options
Diffstat (limited to 'src/shared/cryptsetup-tpm2.c')
| -rw-r--r-- | src/shared/cryptsetup-tpm2.c | 302 |
1 files changed, 302 insertions, 0 deletions
diff --git a/src/shared/cryptsetup-tpm2.c b/src/shared/cryptsetup-tpm2.c new file mode 100644 index 0000000..bfd7d3a --- /dev/null +++ b/src/shared/cryptsetup-tpm2.c @@ -0,0 +1,302 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include "alloc-util.h" +#include "ask-password-api.h" +#include "cryptsetup-tpm2.h" +#include "env-util.h" +#include "fileio.h" +#include "hexdecoct.h" +#include "json.h" +#include "parse-util.h" +#include "random-util.h" +#include "sha256.h" +#include "tpm2-util.h" + +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 = { + .message = "Please enter TPM2 PIN:", + .icon = "drive-harddisk", + .keyring = "tpm2-pin", + .credential = askpw_credential, + }; + + pin = strv_free_erase(pin); + r = ask_password_auto(&req, until, 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; +} + +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 *key_data, + const struct iovec *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) { + + _cleanup_(json_variant_unrefp) JsonVariant *signature_json = NULL; + _cleanup_free_ void *loaded_blob = NULL; + _cleanup_free_ char *auto_device = NULL; + struct iovec blob; + 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 (iovec_is_set(key_data)) + blob = *key_data; + else { + _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, &blob.iov_len); + if (r < 0) + return r; + + blob.iov_base = loaded_blob; + } + + 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, + &blob, + policy_hash, + srk, + ret_decrypted_key); + 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; + + 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, + &blob, + policy_hash, + srk, + ret_decrypted_key); + if (r < 0) { + log_error_errno(r, "Failed to unseal secret using TPM2: %m"); + + /* We get this error in case there is an authentication policy mismatch. This should + * not happen, but this avoids confusing behavior, just in case. */ + if (!IN_SET(r, -EPERM, -ENOLCK)) + continue; + } + + return r; + } +} + +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_blob, + struct iovec *ret_policy_hash, + struct iovec *ret_salt, + struct iovec *ret_srk, + struct iovec *ret_pcrlock_nv, + TPM2Flags *ret_flags, + int *ret_keyslot, + int *ret_token) { + + int r, token; + + assert(cd); + + for (token = start_token; token < sym_crypt_token_max(CRYPT_LUKS2); token++) { + _cleanup_(iovec_done) struct iovec blob = {}, policy_hash = {}, pubkey = {}, salt = {}, srk = {}, pcrlock_nv = {}; + _cleanup_(json_variant_unrefp) JsonVariant *v = NULL; + uint32_t hash_pcr_mask, pubkey_pcr_mask; + uint16_t pcr_bank, primary_alg; + TPM2Flags flags; + int keyslot; + + 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, + &blob, + &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_blob = TAKE_STRUCT(blob); + *ret_policy_hash = TAKE_STRUCT(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."); +} |