diff options
Diffstat (limited to 'src/shared/tpm2-util.c')
| -rw-r--r-- | src/shared/tpm2-util.c | 30 |
1 files changed, 26 insertions, 4 deletions
diff --git a/src/shared/tpm2-util.c b/src/shared/tpm2-util.c index 22b8a872a4..770a1e2b14 100644 --- a/src/shared/tpm2-util.c +++ b/src/shared/tpm2-util.c @@ -4196,6 +4196,11 @@ int tpm2_tpm2b_public_to_openssl_pkey(const TPM2B_PUBLIC *public, EVP_PKEY **ret } } +/* Be careful before changing anything in this function, as the TPM key "name" is calculated using the entire + * TPMT_PUBLIC (after marshalling), and that "name" is used (for example) to calculate the policy hash for + * the Authorize policy. So we must ensure this conversion of a PEM to TPM2B_PUBLIC does not change the + * "name", because it would break unsealing of previously-sealed objects that used (for example) + * tpm2_calculate_policy_authorize(). See bug #30546. */ int tpm2_tpm2b_public_from_openssl_pkey(const EVP_PKEY *pkey, TPM2B_PUBLIC *ret) { int key_id, r; @@ -4274,8 +4279,11 @@ int tpm2_tpm2b_public_from_openssl_pkey(const EVP_PKEY *pkey, TPM2B_PUBLIC *ret) uint32_t exponent = 0; memcpy(&exponent, e, e_size); exponent = be32toh(exponent) >> (32 - e_size * 8); - if (exponent == TPM2_RSA_DEFAULT_EXPONENT) - exponent = 0; + + /* TPM specification Part 2 ("Structures") section for TPMS_RSA_PARAMS states "An exponent of + * zero indicates that the exponent is the default of 2^16 + 1". However, we have no reason + * to special case it in our PEM->TPM2B_PUBLIC conversion, and doing so could break backwards + * compatibility, so even if it is the "default" value of 0x10001, we do not set it to 0. */ public.parameters.rsaDetail.exponent = exponent; break; @@ -5549,11 +5557,25 @@ int tpm2_unseal(Tpm2Context *c, /* If we know the policy hash to expect, and it doesn't match, we can shortcut things here, and not * wait until the TPM2 tells us to go away. */ - if (iovec_is_set(known_policy_hash) && - memcmp_nn(policy_digest->buffer, policy_digest->size, known_policy_hash->iov_base, known_policy_hash->iov_len) != 0) + if (iovec_is_set(known_policy_hash) && memcmp_nn(policy_digest->buffer, + policy_digest->size, + known_policy_hash->iov_base, + known_policy_hash->iov_len) != 0) { +#if HAVE_OPENSSL + if (iovec_is_set(pubkey) && + pubkey_tpm2b.publicArea.type == TPM2_ALG_RSA && + pubkey_tpm2b.publicArea.parameters.rsaDetail.exponent == TPM2_RSA_DEFAULT_EXPONENT) { + /* Due to bug #30546, if using RSA pubkey with the default exponent, we may + * need to set the exponent to the TPM special-case value of 0 and retry. */ + log_debug("Policy hash mismatch, retrying with RSA pubkey exponent set to 0."); + pubkey_tpm2b.publicArea.parameters.rsaDetail.exponent = 0; + continue; + } else +#endif return log_debug_errno(SYNTHETIC_ERRNO(EPERM), "Current policy digest does not match stored policy digest, cancelling " "TPM2 authentication attempt."); + } log_debug("Unsealing HMAC key."); |