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tpm2: add tpm2_policy_auth_value()

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This adds functions to get the digest for a PolicyAuthValue operation. For
building a policy hash, this provides a function to calculate the hash; and for
building a policy hash to satisfy the authPolicy for an existing object, this
provides a function to perform PolicyAuthValue with an existing session.
This commit is contained in:
Dan Streetman 2022-12-09 14:59:05 -05:00
parent dcbc4674e3
commit 8a716354bb
3 changed files with 74 additions and 12 deletions
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75
src/shared/tpm2-util.c
View File

@ -1933,6 +1933,66 @@ static int tpm2_get_name(
return 0;
}
/* Extend 'digest' with the PolicyAuthValue calculated hash. */
int tpm2_calculate_policy_auth_value(TPM2B_DIGEST *digest) {
TPM2_CC command = TPM2_CC_PolicyAuthValue;
TSS2_RC rc;
int r;
assert(digest);
assert(digest->size == SHA256_DIGEST_SIZE);
r = dlopen_tpm2();
if (r < 0)
return log_error_errno(r, "TPM2 support not installed: %m");
uint8_t buf[sizeof(command)];
size_t offset = 0;
rc = sym_Tss2_MU_TPM2_CC_Marshal(command, buf, sizeof(buf), &offset);
if (rc != TSS2_RC_SUCCESS)
return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE),
"Failed to marshal PolicyAuthValue command: %s", sym_Tss2_RC_Decode(rc));
if (offset != sizeof(command))
return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE),
"Offset 0x%zx wrong after marshalling PolicyAuthValue command", offset);
r = tpm2_digest_buffer(TPM2_ALG_SHA256, digest, buf, offset, /* extend= */ true);
if (r < 0)
return r;
tpm2_log_debug_digest(digest, "PolicyAuthValue calculated digest");
return 0;
}
static int tpm2_policy_auth_value(
Tpm2Context *c,
const Tpm2Handle *session,
TPM2B_DIGEST **ret_policy_digest) {
TSS2_RC rc;
assert(c);
assert(session);
log_debug("Adding authValue policy.");
rc = sym_Esys_PolicyAuthValue(
c->esys_context,
session->esys_handle,
ESYS_TR_NONE,
ESYS_TR_NONE,
ESYS_TR_NONE);
if (rc != TSS2_RC_SUCCESS)
return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE),
"Failed to add authValue policy to TPM: %s",
sym_Tss2_RC_Decode(rc));
return tpm2_get_policy_digest(c, session, ret_policy_digest);
}
/* Extend 'digest' with the PolicyPCR calculated hash. */
int tpm2_calculate_policy_pcr(
const TPML_PCR_SELECTION *pcr_selection,
@ -2181,18 +2241,9 @@ static int tpm2_build_sealing_policy(
}
if (use_pin) {
log_debug("Configuring PIN policy.");
rc = sym_Esys_PolicyAuthValue(
c->esys_context,
session->esys_handle,
ESYS_TR_NONE,
ESYS_TR_NONE,
ESYS_TR_NONE);
if (rc != TSS2_RC_SUCCESS)
return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE),
"Failed to add authValue policy to TPM: %s",
sym_Tss2_RC_Decode(rc));
r = tpm2_policy_auth_value(c, session, NULL);
if (r < 0)
return r;
}
r = tpm2_get_policy_digest(c, session, ret_policy_digest);

1
src/shared/tpm2-util.h
View File

@ -90,6 +90,7 @@ static inline int tpm2_digest_init(TPMI_ALG_HASH alg, TPM2B_DIGEST *digest) {
}
int tpm2_calculate_name(const TPMT_PUBLIC *public, TPM2B_NAME *ret_name);
int tpm2_calculate_policy_auth_value(TPM2B_DIGEST *digest);
int tpm2_calculate_policy_pcr(const TPML_PCR_SELECTION *pcr_selection, const TPM2B_DIGEST pcr_values[], size_t pcr_values_count, TPM2B_DIGEST *digest);
int tpm2_seal(const char *device, uint32_t hash_pcr_mask, const void *pubkey, size_t pubkey_size, uint32_t pubkey_pcr_mask, const char *pin, void **ret_secret, size_t *ret_secret_size, void **ret_blob, size_t *ret_blob_size, void **ret_pcr_hash, size_t *ret_pcr_hash_size, uint16_t *ret_pcr_bank, uint16_t *ret_primary_alg, void **ret_srk_buf, size_t *ret_srk_buf_size);

10
src/test/test-tpm2.c
View File

@ -690,6 +690,16 @@ TEST(calculate_name) {
assert_se(streq(expect, h));
}
TEST(calculate_policy_auth_value) {
TPM2B_DIGEST d;
digest_init_sha256(&d, "0000000000000000000000000000000000000000000000000000000000000000");
assert_se(tpm2_calculate_policy_auth_value(&d) == 0);
assert_se(digest_check(&d, "8fcd2169ab92694e0c633f1ab772842b8241bbc20288981fc7ac1eddc1fddb0e"));
assert_se(tpm2_calculate_policy_auth_value(&d) == 0);
assert_se(digest_check(&d, "759ebd5ed65100e0b4aa2d04b4b789c2672d92ecc9cdda4b5fa16a303132e008"));
}
TEST(calculate_policy_pcr) {
TPML_PCR_SELECTION pcr_selection;
TPM2B_DIGEST pcr_values[16];