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/* 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 "hexdecoct.h"
#include "json.h"
#include "memory-util.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 pcr_mask,
bool use_pin) {
_cleanup_(erase_and_freep) void *secret = NULL, *secret2 = NULL;
_cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
_cleanup_(erase_and_freep) char *base64_encoded = NULL;
size_t secret_size, secret2_size, blob_size, hash_size;
_cleanup_free_ void *blob = NULL, *hash = NULL;
uint16_t pcr_bank, primary_alg;
const char *node;
_cleanup_(erase_and_freep) char *pin_str = NULL;
int r, keyslot;
TPM2Flags flags = 0;
assert(cd);
assert(volume_key);
assert(volume_key_size > 0);
assert(TPM2_PCR_MASK_VALID(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 = tpm2_seal(device, 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. */
log_debug("Unsealing for verification...");
r = tpm2_unseal(device, pcr_mask, pcr_bank, primary_alg, blob, blob_size, hash, hash_size, pin_str, &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. */
r = base64mem(secret, secret_size, &base64_encoded);
if (r < 0)
return log_error_errno(r, "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,
strlen(base64_encoded));
if (keyslot < 0)
return log_error_errno(keyslot, "Failed to add new TPM2 key to %s: %m", node);
r = tpm2_make_luks2_json(keyslot, pcr_mask, pcr_bank, primary_alg, blob, blob_size, hash, hash_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;
}
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