/* * Copyright 2006-2016 The OpenSSL Project Authors. All Rights Reserved. * * Licensed under the OpenSSL license (the "License"). You may not use * this file except in compliance with the License. You can obtain a copy * in the file LICENSE in the source distribution or at * https://www.openssl.org/source/license.html */ #include #include "internal/cryptlib.h" #include #include #include #include "ts_local.h" static int ts_verify_cert(X509_STORE *store, STACK_OF(X509) *untrusted, X509 *signer, STACK_OF(X509) **chain); static int ts_check_signing_certs(PKCS7_SIGNER_INFO *si, STACK_OF(X509) *chain); static ESS_SIGNING_CERT *ess_get_signing_cert(PKCS7_SIGNER_INFO *si); static int ts_find_cert(STACK_OF(ESS_CERT_ID) *cert_ids, X509 *cert); static int ts_issuer_serial_cmp(ESS_ISSUER_SERIAL *is, X509 *cert); static int int_ts_RESP_verify_token(TS_VERIFY_CTX *ctx, PKCS7 *token, TS_TST_INFO *tst_info); static int ts_check_status_info(TS_RESP *response); static char *ts_get_status_text(STACK_OF(ASN1_UTF8STRING) *text); static int ts_check_policy(const ASN1_OBJECT *req_oid, const TS_TST_INFO *tst_info); static int ts_compute_imprint(BIO *data, TS_TST_INFO *tst_info, X509_ALGOR **md_alg, unsigned char **imprint, unsigned *imprint_len); static int ts_check_imprints(X509_ALGOR *algor_a, const unsigned char *imprint_a, unsigned len_a, TS_TST_INFO *tst_info); static int ts_check_nonces(const ASN1_INTEGER *a, TS_TST_INFO *tst_info); static int ts_check_signer_name(GENERAL_NAME *tsa_name, X509 *signer); static int ts_find_name(STACK_OF(GENERAL_NAME) *gen_names, GENERAL_NAME *name); static int ts_find_cert_v2(STACK_OF(ESS_CERT_ID_V2) *cert_ids, X509 *cert); static ESS_SIGNING_CERT_V2 *ess_get_signing_cert_v2(PKCS7_SIGNER_INFO *si); /* * This must be large enough to hold all values in ts_status_text (with * comma separator) or all text fields in ts_failure_info (also with comma). */ #define TS_STATUS_BUF_SIZE 256 /* * Local mapping between response codes and descriptions. */ static const char *ts_status_text[] = { "granted", "grantedWithMods", "rejection", "waiting", "revocationWarning", "revocationNotification" }; #define TS_STATUS_TEXT_SIZE OSSL_NELEM(ts_status_text) static struct { int code; const char *text; } ts_failure_info[] = { {TS_INFO_BAD_ALG, "badAlg"}, {TS_INFO_BAD_REQUEST, "badRequest"}, {TS_INFO_BAD_DATA_FORMAT, "badDataFormat"}, {TS_INFO_TIME_NOT_AVAILABLE, "timeNotAvailable"}, {TS_INFO_UNACCEPTED_POLICY, "unacceptedPolicy"}, {TS_INFO_UNACCEPTED_EXTENSION, "unacceptedExtension"}, {TS_INFO_ADD_INFO_NOT_AVAILABLE, "addInfoNotAvailable"}, {TS_INFO_SYSTEM_FAILURE, "systemFailure"} }; /*- * This function carries out the following tasks: * - Checks if there is one and only one signer. * - Search for the signing certificate in 'certs' and in the response. * - Check the extended key usage and key usage fields of the signer * certificate (done by the path validation). * - Build and validate the certificate path. * - Check if the certificate path meets the requirements of the * SigningCertificate ESS signed attribute. * - Verify the signature value. * - Returns the signer certificate in 'signer', if 'signer' is not NULL. */ int TS_RESP_verify_signature(PKCS7 *token, STACK_OF(X509) *certs, X509_STORE *store, X509 **signer_out) { STACK_OF(PKCS7_SIGNER_INFO) *sinfos = NULL; PKCS7_SIGNER_INFO *si; STACK_OF(X509) *signers = NULL; X509 *signer; STACK_OF(X509) *chain = NULL; char buf[4096]; int i, j = 0, ret = 0; BIO *p7bio = NULL; /* Some sanity checks first. */ if (!token) { TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_INVALID_NULL_POINTER); goto err; } if (!PKCS7_type_is_signed(token)) { TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_WRONG_CONTENT_TYPE); goto err; } sinfos = PKCS7_get_signer_info(token); if (!sinfos || sk_PKCS7_SIGNER_INFO_num(sinfos) != 1) { TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_THERE_MUST_BE_ONE_SIGNER); goto err; } si = sk_PKCS7_SIGNER_INFO_value(sinfos, 0); if (PKCS7_get_detached(token)) { TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_NO_CONTENT); goto err; } /* * Get hold of the signer certificate, search only internal certificates * if it was requested. */ signers = PKCS7_get0_signers(token, certs, 0); if (!signers || sk_X509_num(signers) != 1) goto err; signer = sk_X509_value(signers, 0); if (!ts_verify_cert(store, certs, signer, &chain)) goto err; if (!ts_check_signing_certs(si, chain)) goto err; p7bio = PKCS7_dataInit(token, NULL); /* We now have to 'read' from p7bio to calculate digests etc. */ while ((i = BIO_read(p7bio, buf, sizeof(buf))) > 0) continue; j = PKCS7_signatureVerify(p7bio, token, si, signer); if (j <= 0) { TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_SIGNATURE_FAILURE); goto err; } if (signer_out) { *signer_out = signer; X509_up_ref(signer); } ret = 1; err: BIO_free_all(p7bio); sk_X509_pop_free(chain, X509_free); sk_X509_free(signers); return ret; } /* * The certificate chain is returned in chain. Caller is responsible for * freeing the vector. */ static int ts_verify_cert(X509_STORE *store, STACK_OF(X509) *untrusted, X509 *signer, STACK_OF(X509) **chain) { X509_STORE_CTX *cert_ctx = NULL; int i; int ret = 0; *chain = NULL; cert_ctx = X509_STORE_CTX_new(); if (cert_ctx == NULL) { TSerr(TS_F_TS_VERIFY_CERT, ERR_R_MALLOC_FAILURE); goto err; } if (!X509_STORE_CTX_init(cert_ctx, store, signer, untrusted)) goto end; X509_STORE_CTX_set_purpose(cert_ctx, X509_PURPOSE_TIMESTAMP_SIGN); i = X509_verify_cert(cert_ctx); if (i <= 0) { int j = X509_STORE_CTX_get_error(cert_ctx); TSerr(TS_F_TS_VERIFY_CERT, TS_R_CERTIFICATE_VERIFY_ERROR); ERR_add_error_data(2, "Verify error:", X509_verify_cert_error_string(j)); goto err; } *chain = X509_STORE_CTX_get1_chain(cert_ctx); ret = 1; goto end; err: ret = 0; end: X509_STORE_CTX_free(cert_ctx); return ret; } static int ts_check_signing_certs(PKCS7_SIGNER_INFO *si, STACK_OF(X509) *chain) { ESS_SIGNING_CERT *ss = ess_get_signing_cert(si); STACK_OF(ESS_CERT_ID) *cert_ids = NULL; ESS_SIGNING_CERT_V2 *ssv2 = ess_get_signing_cert_v2(si); STACK_OF(ESS_CERT_ID_V2) *cert_ids_v2 = NULL; X509 *cert; int i = 0; int ret = 0; if (ss != NULL) { cert_ids = ss->cert_ids; cert = sk_X509_value(chain, 0); if (ts_find_cert(cert_ids, cert) != 0) goto err; /* * Check the other certificates of the chain if there are more than one * certificate ids in cert_ids. */ if (sk_ESS_CERT_ID_num(cert_ids) > 1) { for (i = 1; i < sk_X509_num(chain); ++i) { cert = sk_X509_value(chain, i); if (ts_find_cert(cert_ids, cert) < 0) goto err; } } } else if (ssv2 != NULL) { cert_ids_v2 = ssv2->cert_ids; cert = sk_X509_value(chain, 0); if (ts_find_cert_v2(cert_ids_v2, cert) != 0) goto err; /* * Check the other certificates of the chain if there are more than one * certificate ids in cert_ids. */ if (sk_ESS_CERT_ID_V2_num(cert_ids_v2) > 1) { for (i = 1; i < sk_X509_num(chain); ++i) { cert = sk_X509_value(chain, i); if (ts_find_cert_v2(cert_ids_v2, cert) < 0) goto err; } } } else { goto err; } ret = 1; err: if (!ret) TSerr(TS_F_TS_CHECK_SIGNING_CERTS, TS_R_ESS_SIGNING_CERTIFICATE_ERROR); ESS_SIGNING_CERT_free(ss); ESS_SIGNING_CERT_V2_free(ssv2); return ret; } static ESS_SIGNING_CERT *ess_get_signing_cert(PKCS7_SIGNER_INFO *si) { ASN1_TYPE *attr; const unsigned char *p; attr = PKCS7_get_signed_attribute(si, NID_id_smime_aa_signingCertificate); if (!attr) return NULL; p = attr->value.sequence->data; return d2i_ESS_SIGNING_CERT(NULL, &p, attr->value.sequence->length); } static ESS_SIGNING_CERT_V2 *ess_get_signing_cert_v2(PKCS7_SIGNER_INFO *si) { ASN1_TYPE *attr; const unsigned char *p; attr = PKCS7_get_signed_attribute(si, NID_id_smime_aa_signingCertificateV2); if (attr == NULL) return NULL; p = attr->value.sequence->data; return d2i_ESS_SIGNING_CERT_V2(NULL, &p, attr->value.sequence->length); } /* Returns < 0 if certificate is not found, certificate index otherwise. */ static int ts_find_cert(STACK_OF(ESS_CERT_ID) *cert_ids, X509 *cert) { int i; unsigned char cert_sha1[SHA_DIGEST_LENGTH]; if (!cert_ids || !cert) return -1; X509_digest(cert, EVP_sha1(), cert_sha1, NULL); /* Recompute SHA1 hash of certificate if necessary (side effect). */ X509_check_purpose(cert, -1, 0); /* Look for cert in the cert_ids vector. */ for (i = 0; i < sk_ESS_CERT_ID_num(cert_ids); ++i) { ESS_CERT_ID *cid = sk_ESS_CERT_ID_value(cert_ids, i); if (cid->hash->length == SHA_DIGEST_LENGTH && memcmp(cid->hash->data, cert_sha1, SHA_DIGEST_LENGTH) == 0) { ESS_ISSUER_SERIAL *is = cid->issuer_serial; if (!is || !ts_issuer_serial_cmp(is, cert)) return i; } } return -1; } /* Returns < 0 if certificate is not found, certificate index otherwise. */ static int ts_find_cert_v2(STACK_OF(ESS_CERT_ID_V2) *cert_ids, X509 *cert) { int i; unsigned char cert_digest[EVP_MAX_MD_SIZE]; unsigned int len; /* Look for cert in the cert_ids vector. */ for (i = 0; i < sk_ESS_CERT_ID_V2_num(cert_ids); ++i) { ESS_CERT_ID_V2 *cid = sk_ESS_CERT_ID_V2_value(cert_ids, i); const EVP_MD *md; if (cid->hash_alg != NULL) md = EVP_get_digestbyobj(cid->hash_alg->algorithm); else md = EVP_sha256(); X509_digest(cert, md, cert_digest, &len); if (cid->hash->length != (int)len) return -1; if (memcmp(cid->hash->data, cert_digest, cid->hash->length) == 0) { ESS_ISSUER_SERIAL *is = cid->issuer_serial; if (is == NULL || !ts_issuer_serial_cmp(is, cert)) return i; } } return -1; } static int ts_issuer_serial_cmp(ESS_ISSUER_SERIAL *is, X509 *cert) { GENERAL_NAME *issuer; if (!is || !cert || sk_GENERAL_NAME_num(is->issuer) != 1) return -1; issuer = sk_GENERAL_NAME_value(is->issuer, 0); if (issuer->type != GEN_DIRNAME || X509_NAME_cmp(issuer->d.dirn, X509_get_issuer_name(cert))) return -1; if (ASN1_INTEGER_cmp(is->serial, X509_get_serialNumber(cert))) return -1; return 0; } /*- * Verifies whether 'response' contains a valid response with regards * to the settings of the context: * - Gives an error message if the TS_TST_INFO is not present. * - Calls _TS_RESP_verify_token to verify the token content. */ int TS_RESP_verify_response(TS_VERIFY_CTX *ctx, TS_RESP *response) { PKCS7 *token = response->token; TS_TST_INFO *tst_info = response->tst_info; int ret = 0; if (!ts_check_status_info(response)) goto err; if (!int_ts_RESP_verify_token(ctx, token, tst_info)) goto err; ret = 1; err: return ret; } /* * Tries to extract a TS_TST_INFO structure from the PKCS7 token and * calls the internal int_TS_RESP_verify_token function for verifying it. */ int TS_RESP_verify_token(TS_VERIFY_CTX *ctx, PKCS7 *token) { TS_TST_INFO *tst_info = PKCS7_to_TS_TST_INFO(token); int ret = 0; if (tst_info) { ret = int_ts_RESP_verify_token(ctx, token, tst_info); TS_TST_INFO_free(tst_info); } return ret; } /*- * Verifies whether the 'token' contains a valid time stamp token * with regards to the settings of the context. Only those checks are * carried out that are specified in the context: * - Verifies the signature of the TS_TST_INFO. * - Checks the version number of the response. * - Check if the requested and returned policies math. * - Check if the message imprints are the same. * - Check if the nonces are the same. * - Check if the TSA name matches the signer. * - Check if the TSA name is the expected TSA. */ static int int_ts_RESP_verify_token(TS_VERIFY_CTX *ctx, PKCS7 *token, TS_TST_INFO *tst_info) { X509 *signer = NULL; GENERAL_NAME *tsa_name = tst_info->tsa; X509_ALGOR *md_alg = NULL; unsigned char *imprint = NULL; unsigned imprint_len = 0; int ret = 0; int flags = ctx->flags; /* Some options require us to also check the signature */ if (((flags & TS_VFY_SIGNER) && tsa_name != NULL) || (flags & TS_VFY_TSA_NAME)) { flags |= TS_VFY_SIGNATURE; } if ((flags & TS_VFY_SIGNATURE) && !TS_RESP_verify_signature(token, ctx->certs, ctx->store, &signer)) goto err; if ((flags & TS_VFY_VERSION) && TS_TST_INFO_get_version(tst_info) != 1) { TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_UNSUPPORTED_VERSION); goto err; } if ((flags & TS_VFY_POLICY) && !ts_check_policy(ctx->policy, tst_info)) goto err; if ((flags & TS_VFY_IMPRINT) && !ts_check_imprints(ctx->md_alg, ctx->imprint, ctx->imprint_len, tst_info)) goto err; if ((flags & TS_VFY_DATA) && (!ts_compute_imprint(ctx->data, tst_info, &md_alg, &imprint, &imprint_len) || !ts_check_imprints(md_alg, imprint, imprint_len, tst_info))) goto err; if ((flags & TS_VFY_NONCE) && !ts_check_nonces(ctx->nonce, tst_info)) goto err; if ((flags & TS_VFY_SIGNER) && tsa_name && !ts_check_signer_name(tsa_name, signer)) { TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_TSA_NAME_MISMATCH); goto err; } if ((flags & TS_VFY_TSA_NAME) && !ts_check_signer_name(ctx->tsa_name, signer)) { TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_TSA_UNTRUSTED); goto err; } ret = 1; err: X509_free(signer); X509_ALGOR_free(md_alg); OPENSSL_free(imprint); return ret; } static int ts_check_status_info(TS_RESP *response) { TS_STATUS_INFO *info = response->status_info; long status = ASN1_INTEGER_get(info->status); const char *status_text = NULL; char *embedded_status_text = NULL; char failure_text[TS_STATUS_BUF_SIZE] = ""; if (status == 0 || status == 1) return 1; /* There was an error, get the description in status_text. */ if (0 <= status && status < (long) OSSL_NELEM(ts_status_text)) status_text = ts_status_text[status]; else status_text = "unknown code"; if (sk_ASN1_UTF8STRING_num(info->text) > 0 && (embedded_status_text = ts_get_status_text(info->text)) == NULL) return 0; /* Fill in failure_text with the failure information. */ if (info->failure_info) { int i; int first = 1; for (i = 0; i < (int)OSSL_NELEM(ts_failure_info); ++i) { if (ASN1_BIT_STRING_get_bit(info->failure_info, ts_failure_info[i].code)) { if (!first) strcat(failure_text, ","); else first = 0; strcat(failure_text, ts_failure_info[i].text); } } } if (failure_text[0] == '\0') strcpy(failure_text, "unspecified"); TSerr(TS_F_TS_CHECK_STATUS_INFO, TS_R_NO_TIME_STAMP_TOKEN); ERR_add_error_data(6, "status code: ", status_text, ", status text: ", embedded_status_text ? embedded_status_text : "unspecified", ", failure codes: ", failure_text); OPENSSL_free(embedded_status_text); return 0; } static char *ts_get_status_text(STACK_OF(ASN1_UTF8STRING) *text) { int i; int length = 0; char *result = NULL; char *p; for (i = 0; i < sk_ASN1_UTF8STRING_num(text); ++i) { ASN1_UTF8STRING *current = sk_ASN1_UTF8STRING_value(text, i); if (ASN1_STRING_length(current) > TS_MAX_STATUS_LENGTH - length - 1) return NULL; length += ASN1_STRING_length(current); length += 1; /* separator character */ } if ((result = OPENSSL_malloc(length)) == NULL) { TSerr(TS_F_TS_GET_STATUS_TEXT, ERR_R_MALLOC_FAILURE); return NULL; } for (i = 0, p = result; i < sk_ASN1_UTF8STRING_num(text); ++i) { ASN1_UTF8STRING *current = sk_ASN1_UTF8STRING_value(text, i); length = ASN1_STRING_length(current); if (i > 0) *p++ = '/'; strncpy(p, (const char *)ASN1_STRING_get0_data(current), length); p += length; } *p = '\0'; return result; } static int ts_check_policy(const ASN1_OBJECT *req_oid, const TS_TST_INFO *tst_info) { const ASN1_OBJECT *resp_oid = tst_info->policy_id; if (OBJ_cmp(req_oid, resp_oid) != 0) { TSerr(TS_F_TS_CHECK_POLICY, TS_R_POLICY_MISMATCH); return 0; } return 1; } static int ts_compute_imprint(BIO *data, TS_TST_INFO *tst_info, X509_ALGOR **md_alg, unsigned char **imprint, unsigned *imprint_len) { TS_MSG_IMPRINT *msg_imprint = tst_info->msg_imprint; X509_ALGOR *md_alg_resp = msg_imprint->hash_algo; const EVP_MD *md; EVP_MD_CTX *md_ctx = NULL; unsigned char buffer[4096]; int length; *md_alg = NULL; *imprint = NULL; if ((*md_alg = X509_ALGOR_dup(md_alg_resp)) == NULL) goto err; if ((md = EVP_get_digestbyobj((*md_alg)->algorithm)) == NULL) { TSerr(TS_F_TS_COMPUTE_IMPRINT, TS_R_UNSUPPORTED_MD_ALGORITHM); goto err; } length = EVP_MD_size(md); if (length < 0) goto err; *imprint_len = length; if ((*imprint = OPENSSL_malloc(*imprint_len)) == NULL) { TSerr(TS_F_TS_COMPUTE_IMPRINT, ERR_R_MALLOC_FAILURE); goto err; } md_ctx = EVP_MD_CTX_new(); if (md_ctx == NULL) { TSerr(TS_F_TS_COMPUTE_IMPRINT, ERR_R_MALLOC_FAILURE); goto err; } if (!EVP_DigestInit(md_ctx, md)) goto err; while ((length = BIO_read(data, buffer, sizeof(buffer))) > 0) { if (!EVP_DigestUpdate(md_ctx, buffer, length)) goto err; } if (!EVP_DigestFinal(md_ctx, *imprint, NULL)) goto err; EVP_MD_CTX_free(md_ctx); return 1; err: EVP_MD_CTX_free(md_ctx); X509_ALGOR_free(*md_alg); OPENSSL_free(*imprint); *imprint_len = 0; *imprint = 0; return 0; } static int ts_check_imprints(X509_ALGOR *algor_a, const unsigned char *imprint_a, unsigned len_a, TS_TST_INFO *tst_info) { TS_MSG_IMPRINT *b = tst_info->msg_imprint; X509_ALGOR *algor_b = b->hash_algo; int ret = 0; if (algor_a) { if (OBJ_cmp(algor_a->algorithm, algor_b->algorithm)) goto err; /* The parameter must be NULL in both. */ if ((algor_a->parameter && ASN1_TYPE_get(algor_a->parameter) != V_ASN1_NULL) || (algor_b->parameter && ASN1_TYPE_get(algor_b->parameter) != V_ASN1_NULL)) goto err; } ret = len_a == (unsigned)ASN1_STRING_length(b->hashed_msg) && memcmp(imprint_a, ASN1_STRING_get0_data(b->hashed_msg), len_a) == 0; err: if (!ret) TSerr(TS_F_TS_CHECK_IMPRINTS, TS_R_MESSAGE_IMPRINT_MISMATCH); return ret; } static int ts_check_nonces(const ASN1_INTEGER *a, TS_TST_INFO *tst_info) { const ASN1_INTEGER *b = tst_info->nonce; if (!b) { TSerr(TS_F_TS_CHECK_NONCES, TS_R_NONCE_NOT_RETURNED); return 0; } /* No error if a nonce is returned without being requested. */ if (ASN1_INTEGER_cmp(a, b) != 0) { TSerr(TS_F_TS_CHECK_NONCES, TS_R_NONCE_MISMATCH); return 0; } return 1; } /* * Check if the specified TSA name matches either the subject or one of the * subject alternative names of the TSA certificate. */ static int ts_check_signer_name(GENERAL_NAME *tsa_name, X509 *signer) { STACK_OF(GENERAL_NAME) *gen_names = NULL; int idx = -1; int found = 0; if (tsa_name->type == GEN_DIRNAME && X509_name_cmp(tsa_name->d.dirn, X509_get_subject_name(signer)) == 0) return 1; gen_names = X509_get_ext_d2i(signer, NID_subject_alt_name, NULL, &idx); while (gen_names != NULL) { found = ts_find_name(gen_names, tsa_name) >= 0; if (found) break; /* * Get the next subject alternative name, although there should be no * more than one. */ GENERAL_NAMES_free(gen_names); gen_names = X509_get_ext_d2i(signer, NID_subject_alt_name, NULL, &idx); } GENERAL_NAMES_free(gen_names); return found; } /* Returns 1 if name is in gen_names, 0 otherwise. */ static int ts_find_name(STACK_OF(GENERAL_NAME) *gen_names, GENERAL_NAME *name) { int i, found; for (i = 0, found = 0; !found && i < sk_GENERAL_NAME_num(gen_names); ++i) { GENERAL_NAME *current = sk_GENERAL_NAME_value(gen_names, i); found = GENERAL_NAME_cmp(current, name) == 0; } return found ? i - 1 : -1; }