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FAPI: Add reading of intermediate certificates from NV ram.
TCG's EK credential profile allows the storage of intermediate certificates in the address range 0x01c00100 - 0x01c001ff. The EK verification using these certificates if available is now implemented. Signed-off-by: Juergen Repp <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,207 @@ | ||
| /* SPDX-License-Identifier: BSD-2-Clause */ | ||
| #ifdef HAVE_CONFIG_H | ||
| #include "config.h" // for HAVE_CURL_URL_STRERROR | ||
| #endif | ||
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|
||
| #include <openssl/bio.h> // for BIO_free, BIO_new_mem_buf | ||
| #include <openssl/evp.h> // for X509, ASN1_IA5STRING, X509_CRL, DIST_... | ||
| #include <openssl/obj_mac.h> // for NID_crl_distribution_points, NID_info... | ||
| #include <openssl/opensslv.h> // for OPENSSL_VERSION_NUMBER | ||
| #include <openssl/pem.h> // for PEM_read_bio_X509 | ||
| #include <openssl/safestack.h> // for STACK_OF | ||
| #include <openssl/x509.h> // for X509_free, X509_STORE_add_cert, X509_... | ||
| #include <openssl/x509v3.h> // for DIST_POINT_NAME, GENERAL_NAME, ACCESS... | ||
| #include <openssl/err.h> // for ERR_error_string_n, ERR_get_error | ||
| #include <stdbool.h> // for bool, false, true | ||
| #include <stdlib.h> // for free, realloc | ||
| #include <string.h> // for memcpy, strdup, strlen | ||
|
|
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| #if OPENSSL_VERSION_NUMBER < 0x30000000L | ||
| #include <openssl/aes.h> | ||
| #endif | ||
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| #include "fapi_certificates.h" // for root_cert_list | ||
| #include "fapi_int.h" // for OSSL_FREE | ||
| #include "ifapi_curl.h" // for ifapi_get_crl_from_cert | ||
| #include "ifapi_helpers.h" // linked lists... | ||
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||
| #include "ifapi_macros.h" // for goto_if_null2 | ||
|
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| #define LOGMODULE fapi | ||
| #include "util/log.h" // for LOG_ERROR, goto_error, SAFE_FREE, got... | ||
|
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||
| /* Function to find a certificate node by subject from issuer. */ | ||
| static NODE_OBJECT_T | ||
| *find_cert_by_issuer(NODE_OBJECT_T *head, X509_NAME *issuer) { | ||
| NODE_OBJECT_T *current = head; | ||
| while (current) { | ||
| if (X509_NAME_cmp(X509_get_subject_name(current->object), issuer) == 0) { | ||
| return current; | ||
| } | ||
| current = current->next; | ||
| } | ||
| return NULL; | ||
| } | ||
|
|
||
| static TSS2_RC | ||
| construct_cert_chain(NODE_OBJECT_T *cert_list, X509 *ek_cert, STACK_OF(X509) *chain, | ||
| X509_STORE *store) { | ||
| TSS2_RC r; | ||
| NODE_OBJECT_T *current = NULL; | ||
| X509_CRL *ek_crl = NULL; | ||
| X509_CRL *crl = NULL; | ||
|
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| /* Add crl for EK to store */ | ||
| r = ifapi_get_crl_from_cert(ek_cert, &ek_crl); | ||
| return_if_error(r, "Get crl for EK certificate."); | ||
|
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||
| if (ek_crl) { | ||
| /* Set the flags of the store to use CRLs. */ | ||
| X509_STORE_set_flags(store, X509_V_FLAG_CRL_CHECK | X509_V_FLAG_CRL_CHECK_ALL); | ||
| if (1 != X509_STORE_add_crl(store, ek_crl)) { | ||
| return_error(TSS2_FAPI_RC_GENERAL_FAILURE, | ||
| "Failed to add EK certificate crl."); | ||
| } | ||
| } | ||
|
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||
| /* Create chain of intermediate certificates from EK certificate. */ | ||
| current = find_cert_by_issuer(cert_list, X509_get_issuer_name(ek_cert)); | ||
| return_if_null(current, "No intermediate certificate found for EK", | ||
| TSS2_FAPI_RC_GENERAL_FAILURE); | ||
|
|
||
| while(current) { | ||
| /* Add crl for intermediate certificate. */ | ||
| r = ifapi_get_crl_from_cert(current->object, &crl); | ||
| return_if_error(r, "Get crl for intermediate certificate."); | ||
|
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||
| if (crl) { | ||
| /* Set the flags of the store to use CRLs. */ | ||
| X509_STORE_set_flags(store, X509_V_FLAG_CRL_CHECK | X509_V_FLAG_CRL_CHECK_ALL); | ||
| if (1 != X509_STORE_add_crl(store, crl)) { | ||
| return_error(TSS2_FAPI_RC_GENERAL_FAILURE, | ||
| "Failed to add intermediate crl."); | ||
| } | ||
| } | ||
| sk_X509_push(chain, current->object); | ||
| current = find_cert_by_issuer(cert_list, X509_get_issuer_name(current->object)); | ||
| } | ||
| return TSS2_RC_SUCCESS; | ||
| } | ||
|
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||
| static X509 | ||
| *get_X509_from_pem(const char *pem_cert) | ||
| { | ||
| if (!pem_cert) { | ||
| return NULL; | ||
| } | ||
| BIO *bufio = NULL; | ||
| X509 *cert = NULL; | ||
|
|
||
| /* Use BIO buffer for conversion */ | ||
| size_t pem_length = strlen(pem_cert); | ||
| bufio = BIO_new_mem_buf((void *)pem_cert, (int) pem_length); | ||
| if (!bufio) | ||
| return NULL; | ||
| /* Convert the certificate */ | ||
| cert = PEM_read_bio_X509(bufio, NULL, NULL, NULL); | ||
| BIO_free(bufio); | ||
| return cert; | ||
| } | ||
|
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||
| /** | ||
| * Verify EK certificate read from TPM with cert list stored in NV ram. | ||
| * | ||
| * @param[in] ek_pem The ek certificate in pem format. | ||
| * @param[in] cert_buff a list of intermediate der cerficicates stored in | ||
| * NV ram. | ||
| * @param[in] cert_bu_size The size of the certificate buffer.. | ||
| * | ||
| * @retval TSS2_RC_SUCCESS on success | ||
| * @retval TSS2_FAPI_RC_GENERAL_FAILURE if an internal error occurred. | ||
| * @retval TSS2_FAPI_RC_MEMORY if not enough memory can be allocated. | ||
| */ | ||
| TSS2_RC | ||
| ifapi_verify_cert_chain(char* ek_pem, uint8_t *cert_buf, size_t cert_buf_size) { | ||
| TSS2_RC r; | ||
| const uint8_t *current_pos = cert_buf; | ||
| size_t remaining_length = cert_buf_size; | ||
| NODE_OBJECT_T *cert_list = NULL; | ||
| X509 *ek_cert = NULL; | ||
| BIO *bio = NULL; | ||
| STACK_OF(X509) *chain = NULL; | ||
| X509_STORE *store = X509_STORE_new(); | ||
| X509_STORE_CTX *store_ctx = NULL; | ||
| X509 *root_cert = NULL; | ||
| X509_STORE_CTX_new(); | ||
|
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| /* Create linked list with all X509 intermediate certificates. */ | ||
| while (remaining_length > 0) { | ||
| X509 *cert = d2i_X509(NULL, ¤t_pos, remaining_length); | ||
| goto_if_null(cert, "Failed to convert DER certificate to X509 certificate.", | ||
| TSS2_FAPI_RC_MEMORY, error); | ||
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| r = append_object_to_list(cert, &cert_list); | ||
| goto_if_error(r, "Failed to create certificate list.", error); | ||
|
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| /* Calculate the length of the current certificate in the buffer. */ | ||
| size_t cert_length = current_pos - (cert_buf + (cert_buf_size - remaining_length)); | ||
| remaining_length -= cert_length; | ||
|
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||
| } | ||
|
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| /* Convert EK certificate from PEM to X509. */ | ||
| bio = BIO_new_mem_buf(ek_pem, -1); | ||
| if (!bio) { | ||
| goto_error(r, TSS2_FAPI_RC_MEMORY, "Out of memory", error); | ||
| } | ||
| ek_cert = PEM_read_bio_X509(bio, NULL, NULL, NULL); | ||
| goto_if_null(ek_cert, "Failed do convert EK certificate", TSS2_FAPI_RC_GENERAL_FAILURE, | ||
| error); | ||
| BIO_free(bio); | ||
| chain = sk_X509_new_null(); | ||
| goto_if_null(chain, "Out of memory", TSS2_FAPI_RC_MEMORY, error); | ||
|
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| store = X509_STORE_new(); | ||
| goto_if_null(store, "Out of memory", TSS2_FAPI_RC_MEMORY, error); | ||
|
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| /* Add intermediate certificates to chain and crls to store. */ | ||
| r = construct_cert_chain(cert_list, ek_cert, chain, store); | ||
| goto_if_error(r, "Failed to construct cert chain.", error); | ||
|
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||
| /* Add stored root certificates */ | ||
| for (uint i = 0; i < sizeof(root_cert_list) / sizeof(char *); i++) { | ||
| root_cert = get_X509_from_pem(root_cert_list[i]); | ||
| goto_if_null(root_cert, "Failed to convert PEM certificate to DER.", | ||
| TSS2_FAPI_RC_BAD_VALUE, error); | ||
| if (1 != X509_STORE_add_cert(store, root_cert)) { | ||
| goto_error(r, TSS2_FAPI_RC_GENERAL_FAILURE, | ||
| "Failed to add root certificate", error); | ||
| } | ||
| OSSL_FREE(root_cert, X509); | ||
| } | ||
|
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||
| /* Verify the certificate chain. */ | ||
| store_ctx = X509_STORE_CTX_new(); | ||
| goto_if_null(store_ctx, "Out of memory", TSS2_FAPI_RC_MEMORY, error); | ||
|
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| if (X509_STORE_CTX_init(store_ctx, store, ek_cert, chain) != 1) { | ||
| goto_error(r, TSS2_FAPI_RC_GENERAL_FAILURE, | ||
| "Failed to init X509 store", error); | ||
| } else if (X509_verify_cert(store_ctx) == 1) { | ||
| /* Verification of EK was successful. */ | ||
| OSSL_FREE(chain, sk_X509); | ||
| OSSL_FREE(store_ctx, X509_STORE_CTX); | ||
| OSSL_FREE(store, X509_STORE); | ||
| return TSS2_RC_SUCCESS; | ||
| } | ||
| LOG_ERROR("EK verification failed"); | ||
| r = TSS2_FAPI_RC_GENERAL_FAILURE; | ||
|
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||
| error: | ||
| OSSL_FREE(chain, sk_X509); | ||
| OSSL_FREE(store_ctx, X509_STORE_CTX); | ||
| OSSL_FREE(store, X509_STORE); | ||
| OSSL_FREE(bio, BIO); | ||
| ifapi_free_node_list(cert_list); | ||
| return r; | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,15 @@ | ||
| /* SPDX-License-Identifier: BSD-2-Clause */ | ||
| #ifndef IFAPI_VERIFY_CERT_CHAIN_H | ||
| #define IFAPI_VERIFY_CERT_CHAIN_H | ||
|
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||
| #include <stddef.h> // for size_t | ||
| #include <openssl/evp.h> // for X509, ASN1_IA5STRING, X509_CRL, DIST_.. | ||
| #include "tss2_common.h" // for TSS2_RC | ||
|
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| TSS2_RC | ||
| ifapi_verify_cert_chain( | ||
| char* ek_pem, | ||
| uint8_t *cert_buf, | ||
| size_t cert_buf_size); | ||
|
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| #endif /* IFAPI_VERIFY_CERT_CHAIN_H */ |