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// OpenVPN -- An application to securely tunnel IP networks
// over a single port, with support for SSL/TLS-based
// session authentication and key exchange,
// packet encryption, packet authentication, and
// packet compression.
//
// Copyright (C) 2012- OpenVPN Inc.
//
// SPDX-License-Identifier: MPL-2.0 OR AGPL-3.0-only WITH openvpn3-openssl-exception
//
// Verify a PKCS7 signature
#ifndef OPENVPN_OPENSSL_SIGN_PKCS7VERIFY_H
#define OPENVPN_OPENSSL_SIGN_PKCS7VERIFY_H
#include <string>
#include <openssl/ssl.h>
#include <openssl/bio.h>
#include <openssl/pkcs7.h>
#include <openvpn/common/cleanup.hpp>
#include <openvpn/common/numeric_cast.hpp>
#include <openvpn/openssl/pki/x509.hpp>
#include <openvpn/openssl/util/error.hpp>
namespace openvpn::OpenSSLSign {
/*
* Verify PKCS7 signature.
* On success, return.
* On fail, throw exception.
*/
inline void verify_pkcs7(const std::list<OpenSSLPKI::X509> &certs,
const std::string &sig,
const std::string &data)
{
STACK_OF(X509) *x509_stack = nullptr;
BIO *in = nullptr;
PKCS7 *p7 = nullptr;
auto clean = Cleanup([&]()
{
if (x509_stack)
sk_X509_free(x509_stack);
if (in)
BIO_free(in);
if (p7)
PKCS7_free(p7); });
/* create x509_stack from cert */
x509_stack = sk_X509_new_null();
for (const auto &cert : certs)
sk_X509_push(x509_stack, cert.obj());
/* get signature */
in = BIO_new_mem_buf(sig.c_str(), numeric_cast<int>(sig.length()));
p7 = PEM_read_bio_PKCS7(in, NULL, NULL, NULL);
if (!p7)
throw OpenSSLException("OpenSSLSign::verify_pkcs7: failed to parse pkcs7 signature");
BIO_free(in);
in = nullptr;
/* get data */
in = BIO_new_mem_buf(data.c_str(), numeric_cast<int>(data.length()));
/* OpenSSL 1.0.2e and higher no longer allows calling PKCS7_verify
with both data and content. Empty out the content if present.
Just calling PKCS7_set_detached call lead to a null pointer access */
if (!PKCS7_is_detached(p7))
PKCS7_set_detached(p7, 1);
/* do the verify */
if (PKCS7_verify(p7, x509_stack, nullptr, in, nullptr, PKCS7_NOVERIFY) != 1)
throw OpenSSLException("OpenSSLSign::verify_pkcs7: verification failed");
}
} // namespace openvpn::OpenSSLSign
#endif
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