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/* -*- indent-tabs-mode: nil -*- */
#include "log/cms_verifier.h"
#include "log/ct_extensions.h"
#include "util/cms_scoped_types.h"
#include "util/openssl_scoped_types.h"
using std::string;
using std::unique_ptr;
using util::Status;
using util::StatusOr;
namespace cert_trans {
util::StatusOr<bool> CmsVerifier::IsCmsSignedByCert(BIO* cms_bio_in,
const Cert& cert) const {
CHECK_NOTNULL(cms_bio_in);
ScopedCMS_ContentInfo cms_content_info(d2i_CMS_bio(cms_bio_in, nullptr));
if (!cms_content_info) {
LOG(ERROR) << "Could not parse CMS data";
LOG_OPENSSL_ERRORS(WARNING);
return Status(util::error::INVALID_ARGUMENT,
"CMS data could not be parsed");
}
// This stack must not be freed as it points into the CMS structure
STACK_OF(CMS_SignerInfo) *
const signers(CMS_get0_SignerInfos(cms_content_info.get()));
if (signers) {
for (int s = 0; s < sk_CMS_SignerInfo_num(signers); ++s) {
CMS_SignerInfo* const signer = sk_CMS_SignerInfo_value(signers, s);
if (CMS_SignerInfo_cert_cmp(signer, cert.x509_.get()) == 0) {
return true;
}
}
}
return false;
}
StatusOr<bool> CmsVerifier::IsCmsSignedByCert(const string& cms_object,
const Cert& cert) const {
// Load a source bio with the CMS signed data object and parse it
ScopedBIO source_bio(BIO_new(BIO_s_mem()));
BIO_write(source_bio.get(), cms_object.c_str(), cms_object.length());
ScopedCMS_ContentInfo cms_content_info(
d2i_CMS_bio(source_bio.get(), nullptr));
if (!cms_content_info) {
LOG(ERROR) << "Could not parse CMS data";
LOG_OPENSSL_ERRORS(WARNING);
return Status(util::error::INVALID_ARGUMENT,
"CMS data could not be parsed");
}
// Now that we've got the CMS unpacked check it has a valid signature using
// the same key as the cert. First create a certificate stack from our
// expected signing cert that can be used by CMS_verify.
ScopedWeakX509Stack validation_chain(sk_X509_new(nullptr));
sk_X509_push(validation_chain.get(), CHECK_NOTNULL(cert.x509_.get()));
// Must set CMS_NOINTERN as the RFC says certs SHOULD be omitted from the
// message but the client might not have obeyed this. CMS_BINARY is required
// to avoid MIME-related translation. CMS_NO_SIGNER_CERT_VERIFY because we
// will do our own checks that the chain is valid and the message may not
// be signed directly by a trusted cert. We don't check it's a signed data
// object CMS type as OpenSSL does this.
const int verified =
CMS_verify(cms_content_info.get(), validation_chain.get(), nullptr,
nullptr, nullptr,
CMS_NO_SIGNER_CERT_VERIFY | CMS_NOINTERN | CMS_BINARY);
if (verified != 1) {
// Most likely, was not CMS signed by the precert
return false;
}
// This stack must not be freed as it points into the CMS structure
STACK_OF(CMS_SignerInfo) *
const signers(CMS_get0_SignerInfos(cms_content_info.get()));
if (signers) {
for (int s = 0; s < sk_CMS_SignerInfo_num(signers); ++s) {
CMS_SignerInfo* const signer = sk_CMS_SignerInfo_value(signers, s);
if (CMS_SignerInfo_cert_cmp(signer, cert.x509_.get()) == 0) {
return true;
}
}
}
return false;
}
util::Status CmsVerifier::UnpackCmsDerBio(BIO* cms_bio_in, const Cert& cert,
BIO* cms_bio_out) {
CHECK_NOTNULL(cms_bio_in);
ScopedCMS_ContentInfo cms_content_info(d2i_CMS_bio(cms_bio_in, nullptr));
if (!cms_content_info) {
LOG(ERROR) << "Could not parse CMS data";
LOG_OPENSSL_ERRORS(WARNING);
return Status(util::error::INVALID_ARGUMENT,
"CMS data could not be parsed");
}
const ASN1_OBJECT* message_content_type(
CMS_get0_eContentType(cms_content_info.get()));
int content_type_nid = OBJ_obj2nid(message_content_type);
// TODO: Enforce content type here. This is not yet defined in the RFC.
if (content_type_nid != NID_ctV2CmsPayloadContentType) {
LOG(WARNING) << "CMS message content has unexpected type: "
<< content_type_nid;
}
// Create a certificate stack from our expected signing cert that can be used
// by CMS_verify.
ScopedWeakX509Stack validation_chain(sk_X509_new(nullptr));
sk_X509_push(validation_chain.get(), cert.x509_.get());
// Must set CMS_NOINTERN as the RFC says certs SHOULD be omitted from the
// message but the client might not have obeyed this. CMS_BINARY is required
// to avoid MIME-related translation. CMS_NO_SIGNER_CERT_VERIFY because we
// will do our own checks that the chain is valid and the message may not
// be signed directly by a trusted cert. We don't check it's a signed data
// object CMS type as OpenSSL does this.
int verified =
CMS_verify(cms_content_info.get(), validation_chain.get(), nullptr,
nullptr, cms_bio_out,
CMS_NO_SIGNER_CERT_VERIFY | CMS_NOINTERN | CMS_BINARY);
return (verified == 1) ? util::Status::OK
: util::Status(util::error::INVALID_ARGUMENT,
"CMS verification failed");
}
util::Status CmsVerifier::UnpackCmsDerBio(BIO* cms_bio_in, BIO* cms_bio_out) {
CHECK_NOTNULL(cms_bio_in);
CHECK_NOTNULL(cms_bio_out);
ScopedCMS_ContentInfo cms_content_info(d2i_CMS_bio(cms_bio_in, nullptr));
if (!cms_content_info) {
LOG(ERROR) << "Could not parse CMS data";
LOG_OPENSSL_ERRORS(WARNING);
return Status(util::error::INVALID_ARGUMENT,
"CMS data could not be parsed");
}
const ASN1_OBJECT* message_content_type(
CMS_get0_eContentType(cms_content_info.get()));
const int content_type_nid = OBJ_obj2nid(message_content_type);
// TODO: Enforce content type here. This is not yet defined in the RFC.
if (content_type_nid != NID_ctV2CmsPayloadContentType) {
LOG(WARNING) << "CMS message content has unexpected type: "
<< content_type_nid;
}
// Must set CMS_NOINTERN as the RFC says certs SHOULD be omitted from the
// message but the client might not have obeyed this. CMS_BINARY is required
// to avoid MIME-related translation. CMS_NO_SIGNER_CERT_VERIFY because we
// will do our own checks that the chain is valid and the message may not
// be signed directly by a trusted cert. CMS_NO_CONTENT_VERIFY because we
// can't apply the RFC mandated signature checks until we have the unpacked
// cert to examine. We don't check it's a signed data object CMS type as
// OpenSSL does this.
const int verified =
CMS_verify(cms_content_info.get(), nullptr, nullptr, nullptr,
cms_bio_out, CMS_NO_SIGNER_CERT_VERIFY | CMS_NOINTERN |
CMS_BINARY | CMS_NO_CONTENT_VERIFY);
return (verified == 1) ? util::Status::OK
: util::Status(util::error::INVALID_ARGUMENT,
"CMS unpack failed");
}
unique_ptr<Cert> CmsVerifier::UnpackCmsSignedCertificate(
BIO* cms_bio_in, const Cert& verify_cert) {
CHECK_NOTNULL(cms_bio_in);
ScopedBIO unpacked_bio(BIO_new(BIO_s_mem()));
unique_ptr<Cert> cert;
if (UnpackCmsDerBio(cms_bio_in, verify_cert, unpacked_bio.get()).ok()) {
// The unpacked data should be a valid DER certificate.
// TODO: The RFC does not yet define this as the format so this may
// need to change.
cert = Cert::FromDerBio(unpacked_bio.get());
if (!cert) {
LOG(WARNING) << "Could not unpack cert from CMS DER encoded data";
}
} else {
LOG_OPENSSL_ERRORS(ERROR);
}
return cert;
}
unique_ptr<Cert> CmsVerifier::UnpackCmsSignedCertificate(
const string& cms_object) {
// Load the source bio with the CMS signed data object
ScopedBIO source_bio(BIO_new(BIO_s_mem()));
BIO_write(source_bio.get(), cms_object.c_str(), cms_object.length());
ScopedBIO unpacked_bio(BIO_new(BIO_s_mem()));
unique_ptr<Cert> cert;
if (UnpackCmsDerBio(source_bio.get(), unpacked_bio.get()).ok()) {
// The unpacked data should be a valid DER certificate.
// TODO: The RFC does not yet define this as the format so this may
// need to change.
cert = Cert::FromDerBio(unpacked_bio.get());
if (!cert) {
LOG(WARNING) << "Could not unpack cert from CMS DER encoded data";
}
} else {
LOG_OPENSSL_ERRORS(ERROR);
}
return cert;
}
} // namespace cert_trans
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