/* * Copyright The Mbed TLS Contributors * SPDX-License-Identifier: Apache-2.0 * * Licensed under the Apache License, Version 2.0 (the "License"); you may * not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include "common.h" #include "mbedtls/build_info.h" #if defined(MBEDTLS_PKCS7_C) #include "mbedtls/pkcs7.h" #include "mbedtls/x509.h" #include "mbedtls/asn1.h" #include "mbedtls/x509_crt.h" #include "mbedtls/x509_crl.h" #include "mbedtls/oid.h" #include "mbedtls/error.h" #include #include #include #if defined(MBEDTLS_FS_IO) #include #include #endif #include "mbedtls/platform.h" #include "mbedtls/platform_util.h" #if defined(MBEDTLS_HAVE_TIME) #include "mbedtls/platform_time.h" #endif #if defined(MBEDTLS_HAVE_TIME_DATE) #include #endif /** * Initializes the pkcs7 structure. */ void mbedtls_pkcs7_init(mbedtls_pkcs7 *pkcs7) { memset(pkcs7, 0, sizeof(*pkcs7)); } static int pkcs7_get_next_content_len(unsigned char **p, unsigned char *end, size_t *len) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; ret = mbedtls_asn1_get_tag(p, end, len, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_CONTEXT_SPECIFIC); if (ret != 0) { ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_FORMAT, ret); } return ret; } /** * version Version * Version ::= INTEGER **/ static int pkcs7_get_version(unsigned char **p, unsigned char *end, int *ver) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; ret = mbedtls_asn1_get_int(p, end, ver); if (ret != 0) { ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_VERSION, ret); } /* If version != 1, return invalid version */ if (*ver != MBEDTLS_PKCS7_SUPPORTED_VERSION) { ret = MBEDTLS_ERR_PKCS7_INVALID_VERSION; } return ret; } /** * ContentInfo ::= SEQUENCE { * contentType ContentType, * content * [0] EXPLICIT ANY DEFINED BY contentType OPTIONAL } **/ static int pkcs7_get_content_info_type(unsigned char **p, unsigned char *end, mbedtls_pkcs7_buf *pkcs7) { size_t len = 0; int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *start = *p; ret = mbedtls_asn1_get_tag(p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE); if (ret != 0) { *p = start; return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_CONTENT_INFO, ret); } ret = mbedtls_asn1_get_tag(p, end, &len, MBEDTLS_ASN1_OID); if (ret != 0) { *p = start; return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_CONTENT_INFO, ret); } pkcs7->tag = MBEDTLS_ASN1_OID; pkcs7->len = len; pkcs7->p = *p; *p += len; return ret; } /** * DigestAlgorithmIdentifier ::= AlgorithmIdentifier * * This is from x509.h **/ static int pkcs7_get_digest_algorithm(unsigned char **p, unsigned char *end, mbedtls_x509_buf *alg) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; if ((ret = mbedtls_asn1_get_alg_null(p, end, alg)) != 0) { ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_ALG, ret); } return ret; } /** * DigestAlgorithmIdentifiers :: SET of DigestAlgorithmIdentifier **/ static int pkcs7_get_digest_algorithm_set(unsigned char **p, unsigned char *end, mbedtls_x509_buf *alg) { size_t len = 0; int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; ret = mbedtls_asn1_get_tag(p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SET); if (ret != 0) { return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_ALG, ret); } end = *p + len; ret = mbedtls_asn1_get_alg_null(p, end, alg); if (ret != 0) { return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_ALG, ret); } /** For now, it assumes there is only one digest algorithm specified **/ if (*p != end) { return MBEDTLS_ERR_PKCS7_FEATURE_UNAVAILABLE; } return 0; } /** * certificates :: SET OF ExtendedCertificateOrCertificate, * ExtendedCertificateOrCertificate ::= CHOICE { * certificate Certificate -- x509, * extendedCertificate[0] IMPLICIT ExtendedCertificate } * Return number of certificates added to the signed data, * 0 or higher is valid. * Return negative error code for failure. **/ static int pkcs7_get_certificates(unsigned char **p, unsigned char *end, mbedtls_x509_crt *certs) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; size_t len1 = 0; size_t len2 = 0; unsigned char *end_set, *end_cert, *start; if ((ret = mbedtls_asn1_get_tag(p, end, &len1, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_CONTEXT_SPECIFIC)) != 0) { if (ret == MBEDTLS_ERR_ASN1_UNEXPECTED_TAG) { return 0; } else { return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_FORMAT, ret); } } start = *p; end_set = *p + len1; ret = mbedtls_asn1_get_tag(p, end_set, &len2, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE); if (ret != 0) { return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_CERT, ret); } end_cert = *p + len2; /* * This is to verify that there is only one signer certificate. It seems it is * not easy to differentiate between the chain vs different signer's certificate. * So, we support only the root certificate and the single signer. * The behaviour would be improved with addition of multiple signer support. */ if (end_cert != end_set) { return MBEDTLS_ERR_PKCS7_FEATURE_UNAVAILABLE; } *p = start; if ((ret = mbedtls_x509_crt_parse_der(certs, *p, len1)) < 0) { return MBEDTLS_ERR_PKCS7_INVALID_CERT; } *p = *p + len1; /* * Since in this version we strictly support single certificate, and reaching * here implies we have parsed successfully, we return 1. */ return 1; } /** * EncryptedDigest ::= OCTET STRING **/ static int pkcs7_get_signature(unsigned char **p, unsigned char *end, mbedtls_pkcs7_buf *signature) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; size_t len = 0; ret = mbedtls_asn1_get_tag(p, end, &len, MBEDTLS_ASN1_OCTET_STRING); if (ret != 0) { return ret; } signature->tag = MBEDTLS_ASN1_OCTET_STRING; signature->len = len; signature->p = *p; *p = *p + len; return 0; } static void pkcs7_free_signer_info(mbedtls_pkcs7_signer_info *signer) { mbedtls_x509_name *name_cur; mbedtls_x509_name *name_prv; if (signer == NULL) { return; } name_cur = signer->issuer.next; while (name_cur != NULL) { name_prv = name_cur; name_cur = name_cur->next; mbedtls_free(name_prv); } signer->issuer.next = NULL; } /** * SignerInfo ::= SEQUENCE { * version Version; * issuerAndSerialNumber IssuerAndSerialNumber, * digestAlgorithm DigestAlgorithmIdentifier, * authenticatedAttributes * [0] IMPLICIT Attributes OPTIONAL, * digestEncryptionAlgorithm DigestEncryptionAlgorithmIdentifier, * encryptedDigest EncryptedDigest, * unauthenticatedAttributes * [1] IMPLICIT Attributes OPTIONAL, * Returns 0 if the signerInfo is valid. * Return negative error code for failure. * Structure must not contain vales for authenticatedAttributes * and unauthenticatedAttributes. **/ static int pkcs7_get_signer_info(unsigned char **p, unsigned char *end, mbedtls_pkcs7_signer_info *signer) { unsigned char *end_signer; int asn1_ret = 0, ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; size_t len = 0; asn1_ret = mbedtls_asn1_get_tag(p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE); if (asn1_ret != 0) { goto out; } end_signer = *p + len; ret = pkcs7_get_version(p, end_signer, &signer->version); if (ret != 0) { goto out; } asn1_ret = mbedtls_asn1_get_tag(p, end_signer, &len, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE); if (asn1_ret != 0) { goto out; } /* Parsing IssuerAndSerialNumber */ signer->issuer_raw.p = *p; asn1_ret = mbedtls_asn1_get_tag(p, end_signer, &len, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE); if (asn1_ret != 0) { goto out; } ret = mbedtls_x509_get_name(p, *p + len, &signer->issuer); if (ret != 0) { goto out; } signer->issuer_raw.len = *p - signer->issuer_raw.p; ret = mbedtls_x509_get_serial(p, end_signer, &signer->serial); if (ret != 0) { goto out; } ret = pkcs7_get_digest_algorithm(p, end_signer, &signer->alg_identifier); if (ret != 0) { goto out; } /* Assume authenticatedAttributes is nonexistent */ ret = pkcs7_get_digest_algorithm(p, end_signer, &signer->sig_alg_identifier); if (ret != 0) { goto out; } ret = pkcs7_get_signature(p, end_signer, &signer->sig); if (ret != 0) { goto out; } /* Do not permit any unauthenticated attributes */ if (*p != end_signer) { ret = MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO; } out: if (asn1_ret != 0 || ret != 0) { pkcs7_free_signer_info(signer); ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO, asn1_ret); } return ret; } /** * SignerInfos ::= SET of SignerInfo * Return number of signers added to the signed data, * 0 or higher is valid. * Return negative error code for failure. **/ static int pkcs7_get_signers_info_set(unsigned char **p, unsigned char *end, mbedtls_pkcs7_signer_info *signers_set) { unsigned char *end_set; int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; int count = 0; size_t len = 0; ret = mbedtls_asn1_get_tag(p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SET); if (ret != 0) { return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_SIGNER_INFO, ret); } /* Detect zero signers */ if (len == 0) { return 0; } end_set = *p + len; ret = pkcs7_get_signer_info(p, end_set, signers_set); if (ret != 0) { return ret; } count++; mbedtls_pkcs7_signer_info *prev = signers_set; while (*p != end_set) { mbedtls_pkcs7_signer_info *signer = mbedtls_calloc(1, sizeof(mbedtls_pkcs7_signer_info)); if (!signer) { ret = MBEDTLS_ERR_PKCS7_ALLOC_FAILED; goto cleanup; } ret = pkcs7_get_signer_info(p, end_set, signer); if (ret != 0) { mbedtls_free(signer); goto cleanup; } prev->next = signer; prev = signer; count++; } return count; cleanup: pkcs7_free_signer_info(signers_set); mbedtls_pkcs7_signer_info *signer = signers_set->next; while (signer != NULL) { prev = signer; signer = signer->next; pkcs7_free_signer_info(prev); mbedtls_free(prev); } signers_set->next = NULL; return ret; } /** * SignedData ::= SEQUENCE { * version Version, * digestAlgorithms DigestAlgorithmIdentifiers, * contentInfo ContentInfo, * certificates * [0] IMPLICIT ExtendedCertificatesAndCertificates * OPTIONAL, * crls * [0] IMPLICIT CertificateRevocationLists OPTIONAL, * signerInfos SignerInfos } */ static int pkcs7_get_signed_data(unsigned char *buf, size_t buflen, mbedtls_pkcs7_signed_data *signed_data) { unsigned char *p = buf; unsigned char *end = buf + buflen; unsigned char *end_set; size_t len = 0; int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; mbedtls_md_type_t md_alg; ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE); if (ret != 0) { return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_FORMAT, ret); } end_set = p + len; /* Get version of signed data */ ret = pkcs7_get_version(&p, end_set, &signed_data->version); if (ret != 0) { return ret; } /* Get digest algorithm */ ret = pkcs7_get_digest_algorithm_set(&p, end_set, &signed_data->digest_alg_identifiers); if (ret != 0) { return ret; } ret = mbedtls_oid_get_md_alg(&signed_data->digest_alg_identifiers, &md_alg); if (ret != 0) { return MBEDTLS_ERR_PKCS7_INVALID_ALG; } /* Do not expect any content */ ret = pkcs7_get_content_info_type(&p, end_set, &signed_data->content.oid); if (ret != 0) { return ret; } if (MBEDTLS_OID_CMP(MBEDTLS_OID_PKCS7_DATA, &signed_data->content.oid)) { return MBEDTLS_ERR_PKCS7_INVALID_CONTENT_INFO; } /* Look for certificates, there may or may not be any */ mbedtls_x509_crt_init(&signed_data->certs); ret = pkcs7_get_certificates(&p, end_set, &signed_data->certs); if (ret < 0) { return ret; } signed_data->no_of_certs = ret; /* * Currently CRLs are not supported. If CRL exist, the parsing will fail * at next step of getting signers info and return error as invalid * signer info. */ signed_data->no_of_crls = 0; /* Get signers info */ ret = pkcs7_get_signers_info_set(&p, end_set, &signed_data->signers); if (ret < 0) { return ret; } signed_data->no_of_signers = ret; /* Don't permit trailing data */ if (p != end) { return MBEDTLS_ERR_PKCS7_INVALID_FORMAT; } return 0; } int mbedtls_pkcs7_parse_der(mbedtls_pkcs7 *pkcs7, const unsigned char *buf, const size_t buflen) { unsigned char *p; unsigned char *end; size_t len = 0; int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; int isoidset = 0; if (pkcs7 == NULL) { return MBEDTLS_ERR_PKCS7_BAD_INPUT_DATA; } /* make an internal copy of the buffer for parsing */ pkcs7->raw.p = p = mbedtls_calloc(1, buflen); if (pkcs7->raw.p == NULL) { ret = MBEDTLS_ERR_PKCS7_ALLOC_FAILED; goto out; } memcpy(p, buf, buflen); pkcs7->raw.len = buflen; end = p + buflen; ret = pkcs7_get_content_info_type(&p, end, &pkcs7->content_type_oid); if (ret != 0) { len = buflen; goto try_data; } if (!MBEDTLS_OID_CMP(MBEDTLS_OID_PKCS7_DATA, &pkcs7->content_type_oid) || !MBEDTLS_OID_CMP(MBEDTLS_OID_PKCS7_ENCRYPTED_DATA, &pkcs7->content_type_oid) || !MBEDTLS_OID_CMP(MBEDTLS_OID_PKCS7_ENVELOPED_DATA, &pkcs7->content_type_oid) || !MBEDTLS_OID_CMP(MBEDTLS_OID_PKCS7_SIGNED_AND_ENVELOPED_DATA, &pkcs7->content_type_oid) || !MBEDTLS_OID_CMP(MBEDTLS_OID_PKCS7_DIGESTED_DATA, &pkcs7->content_type_oid) || !MBEDTLS_OID_CMP(MBEDTLS_OID_PKCS7_ENCRYPTED_DATA, &pkcs7->content_type_oid)) { ret = MBEDTLS_ERR_PKCS7_FEATURE_UNAVAILABLE; goto out; } if (MBEDTLS_OID_CMP(MBEDTLS_OID_PKCS7_SIGNED_DATA, &pkcs7->content_type_oid)) { ret = MBEDTLS_ERR_PKCS7_BAD_INPUT_DATA; goto out; } isoidset = 1; ret = pkcs7_get_next_content_len(&p, end, &len); if (ret != 0) { goto out; } try_data: ret = pkcs7_get_signed_data(p, len, &pkcs7->signed_data); if (ret != 0) { goto out; } if (!isoidset) { pkcs7->content_type_oid.tag = MBEDTLS_ASN1_OID; pkcs7->content_type_oid.len = MBEDTLS_OID_SIZE(MBEDTLS_OID_PKCS7_SIGNED_DATA); pkcs7->content_type_oid.p = (unsigned char *) MBEDTLS_OID_PKCS7_SIGNED_DATA; } ret = MBEDTLS_PKCS7_SIGNED_DATA; out: if (ret < 0) { mbedtls_pkcs7_free(pkcs7); } return ret; } static int mbedtls_pkcs7_data_or_hash_verify(mbedtls_pkcs7 *pkcs7, const mbedtls_x509_crt *cert, const unsigned char *data, size_t datalen, const int is_data_hash) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *hash; mbedtls_pk_context pk_cxt = cert->pk; const mbedtls_md_info_t *md_info; mbedtls_md_type_t md_alg; mbedtls_pkcs7_signer_info *signer; if (pkcs7->signed_data.no_of_signers == 0) { return MBEDTLS_ERR_PKCS7_INVALID_CERT; } if (mbedtls_x509_time_is_past(&cert->valid_to) || mbedtls_x509_time_is_future(&cert->valid_from)) { return MBEDTLS_ERR_PKCS7_CERT_DATE_INVALID; } /* * Potential TODOs * Currently we iterate over all signers and return success if any of them * verify. * * However, we could make this better by checking against the certificate's * identification and SignerIdentifier fields first. That would also allow * us to distinguish between 'no signature for key' and 'signature for key * failed to validate'. * * We could also cache hashes by md, so if there are several sigs all using * the same algo we don't recalculate the hash each time. */ for (signer = &pkcs7->signed_data.signers; signer; signer = signer->next) { ret = mbedtls_oid_get_md_alg(&signer->alg_identifier, &md_alg); if (ret != 0) { ret = MBEDTLS_ERR_PKCS7_VERIFY_FAIL; continue; } md_info = mbedtls_md_info_from_type(md_alg); if (md_info == NULL) { ret = MBEDTLS_ERR_PKCS7_VERIFY_FAIL; continue; } hash = mbedtls_calloc(mbedtls_md_get_size(md_info), 1); if (hash == NULL) { return MBEDTLS_ERR_PKCS7_ALLOC_FAILED; } /* BEGIN must free hash before jumping out */ if (is_data_hash) { if (datalen != mbedtls_md_get_size(md_info)) { ret = MBEDTLS_ERR_PKCS7_VERIFY_FAIL; } else { memcpy(hash, data, datalen); } } else { ret = mbedtls_md(md_info, data, datalen, hash); } if (ret != 0) { ret = MBEDTLS_ERR_PKCS7_VERIFY_FAIL; mbedtls_free(hash); continue; } ret = mbedtls_pk_verify(&pk_cxt, md_alg, hash, mbedtls_md_get_size(md_info), signer->sig.p, signer->sig.len); mbedtls_free(hash); /* END must free hash before jumping out */ if (ret == 0) { break; } } return ret; } int mbedtls_pkcs7_signed_data_verify(mbedtls_pkcs7 *pkcs7, const mbedtls_x509_crt *cert, const unsigned char *data, size_t datalen) { return mbedtls_pkcs7_data_or_hash_verify(pkcs7, cert, data, datalen, 0); } int mbedtls_pkcs7_signed_hash_verify(mbedtls_pkcs7 *pkcs7, const mbedtls_x509_crt *cert, const unsigned char *hash, size_t hashlen) { return mbedtls_pkcs7_data_or_hash_verify(pkcs7, cert, hash, hashlen, 1); } /* * Unallocate all pkcs7 data */ void mbedtls_pkcs7_free(mbedtls_pkcs7 *pkcs7) { mbedtls_pkcs7_signer_info *signer_cur; mbedtls_pkcs7_signer_info *signer_prev; if (pkcs7 == NULL || pkcs7->raw.p == NULL) { return; } mbedtls_free(pkcs7->raw.p); mbedtls_x509_crt_free(&pkcs7->signed_data.certs); mbedtls_x509_crl_free(&pkcs7->signed_data.crl); signer_cur = pkcs7->signed_data.signers.next; pkcs7_free_signer_info(&pkcs7->signed_data.signers); while (signer_cur != NULL) { signer_prev = signer_cur; signer_cur = signer_prev->next; pkcs7_free_signer_info(signer_prev); mbedtls_free(signer_prev); } pkcs7->raw.p = NULL; } #endif