3c2c8e62c9
New API added upstream:
8a12f6dc2c
132 lines
5.2 KiB
C
132 lines
5.2 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include "alloc-util.h"
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#include "cryptenroll-tpm2.h"
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#include "hexdecoct.h"
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#include "json.h"
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#include "memory-util.h"
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#include "tpm2-util.h"
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static int search_policy_hash(
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struct crypt_device *cd,
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const void *hash,
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size_t hash_size) {
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int r;
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assert(cd);
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assert(hash || hash_size == 0);
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if (hash_size == 0)
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return 0;
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for (int token = 0; token < sym_crypt_token_max(CRYPT_LUKS2); token ++) {
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_cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
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_cleanup_free_ void *thash = NULL;
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size_t thash_size = 0;
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int keyslot;
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JsonVariant *w;
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r = cryptsetup_get_token_as_json(cd, token, "systemd-tpm2", &v);
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if (IN_SET(r, -ENOENT, -EINVAL, -EMEDIUMTYPE))
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continue;
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if (r < 0)
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return log_error_errno(r, "Failed to read JSON token data off disk: %m");
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keyslot = cryptsetup_get_keyslot_from_token(v);
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if (keyslot < 0)
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return log_error_errno(keyslot, "Failed to determine keyslot of JSON token: %m");
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w = json_variant_by_key(v, "tpm2-policy-hash");
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if (!w || !json_variant_is_string(w))
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return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
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"TPM2 token data lacks 'tpm2-policy-hash' field.");
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r = unhexmem(json_variant_string(w), (size_t) -1, &thash, &thash_size);
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if (r < 0)
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return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
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"Invalid base64 data in 'tpm2-policy-hash' field.");
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if (memcmp_nn(hash, hash_size, thash, thash_size) == 0)
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return keyslot; /* Found entry with same hash. */
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}
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return -ENOENT; /* Not found */
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}
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int enroll_tpm2(struct crypt_device *cd,
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const void *volume_key,
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size_t volume_key_size,
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const char *device,
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uint32_t pcr_mask) {
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_cleanup_(erase_and_freep) void *secret = NULL, *secret2 = NULL;
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_cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
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_cleanup_(erase_and_freep) char *base64_encoded = NULL;
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size_t secret_size, secret2_size, blob_size, hash_size;
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_cleanup_free_ void *blob = NULL, *hash = NULL;
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const char *node;
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int r, keyslot;
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assert(cd);
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assert(volume_key);
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assert(volume_key_size > 0);
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assert(pcr_mask < (1U << TPM2_PCRS_MAX)); /* Support 24 PCR banks */
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assert_se(node = crypt_get_device_name(cd));
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r = tpm2_seal(device, pcr_mask, &secret, &secret_size, &blob, &blob_size, &hash, &hash_size);
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if (r < 0)
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return r;
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/* Let's see if we already have this specific PCR policy hash enrolled, if so, exit early. */
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r = search_policy_hash(cd, hash, hash_size);
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if (r == -ENOENT)
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log_debug_errno(r, "PCR policy hash not yet enrolled, enrolling now.");
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else if (r < 0)
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return r;
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else {
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log_info("This PCR set is already enrolled, executing no operation.");
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return r; /* return existing keyslot, so that wiping won't kill it */
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}
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/* Quick verification that everything is in order, we are not in a hurry after all. */
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log_debug("Unsealing for verification...");
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r = tpm2_unseal(device, pcr_mask, blob, blob_size, hash, hash_size, &secret2, &secret2_size);
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if (r < 0)
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return r;
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if (memcmp_nn(secret, secret_size, secret2, secret2_size) != 0)
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return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "TPM2 seal/unseal verification failed.");
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/* 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. */
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r = base64mem(secret, secret_size, &base64_encoded);
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if (r < 0)
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return log_error_errno(r, "Failed to base64 encode secret key: %m");
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r = cryptsetup_set_minimal_pbkdf(cd);
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if (r < 0)
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return log_error_errno(r, "Failed to set minimal PBKDF: %m");
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keyslot = crypt_keyslot_add_by_volume_key(
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cd,
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CRYPT_ANY_SLOT,
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volume_key,
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volume_key_size,
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base64_encoded,
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strlen(base64_encoded));
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if (keyslot < 0)
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return log_error_errno(keyslot, "Failed to add new TPM2 key to %s: %m", node);
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r = tpm2_make_luks2_json(keyslot, pcr_mask, blob, blob_size, hash, hash_size, &v);
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if (r < 0)
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return log_error_errno(r, "Failed to prepare TPM2 JSON token object: %m");
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r = cryptsetup_add_token_json(cd, v);
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if (r < 0)
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return log_error_errno(r, "Failed to add TPM2 JSON token to LUKS2 header: %m");
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log_info("New TPM2 token enrolled as key slot %i.", keyslot);
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return keyslot;
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}
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